Mammalian Synthetic Biology: Engineering Biological Systems
Black JB, Perez-Pinera P, Gersbach CA.
Annu Rev Biomed Eng. 2017 Jun 21;19:249-277.
The programming of new functions into mammalian cells has tremendous application in research and medicine. Continued improvements in the capacity to sequence and synthesize DNA have rapidly increased our understanding of mechanisms of gene function and regulation on a genome-wide scale and have expanded the set of genetic components available for programming cell biology. The invention of new research tools, including targetable DNA-binding systems such as CRISPR/Cas9 and sensor-actuator devices that can recognize and respond to diverse chemical, mechanical, and optical inputs, has enabled precise control of complex cellular behaviors at unprecedented spatial and temporal resolution. These tools have been critical for the expansion of synthetic biology techniques from prokaryotic and lower eukaryotic hosts to mammalian systems. Recent progress in the development of genome and epigenome editing tools and in the engineering of designer cells with programmable genetic circuits is expanding approaches to prevent, diagnose, and treat disease and to establish personalized theranostic strategies for next-generation medicines. This review summarizes the development of these enabling technologies and their application to transforming mammalian synthetic biology into a distinct field in research and medicine.
Prosurvival long noncoding RNA PINCR regulates a subset of p53 targets in human colorectal cancer cells by binding to Matrin 3
Chaudhary R, Gryder B, Woods WS, Subramanian M, Jones MF, Li XL, Jenkins LM, Shabalina SA, Mo M, Dasso M, Yang Y, Wakefield LM, Zhu Y, Frier SM, Moriarity BS, Prasanth KV, Perez-Pinera P, Lal A.
Elife. 2017 Jun 5. pii: e23244
Thousands of long noncoding RNAs (lncRNAs) have been discovered, yet the function of the vast majority remains unclear. Here, we show that a p53-regulated lncRNA which we named PINCR (p53-induced noncoding RNA), is induced ~100-fold after DNA damage and exerts a prosurvival function in human colorectal cancer cells (CRC) in vitro and tumor growth in vivo. Targeted deletion of PINCR in CRC cells significantly impaired G1 arrest and induced hypersensitivity to chemotherapeutic drugs. PINCR regulates the induction of a subset of p53 targets involved in G1 arrest and apoptosis, including BTG2, RRM2B and GPX1. Using a novel RNA pulldown approach that utilized endogenous S1-tagged PINCR, we show that PINCR associates with the enhancer region of these genes by binding to RNA-binding protein Matrin 3 that, in turn, associates with p53. Our findings uncover a critical prosurvival function of a p53/PINCR/Matrin 3 axis in response to DNA damage in CRC cells.
Damage, Healing, and Remodeling in Optogenetic Skeletal Muscle Bioactuators
Raman R, Grant L, Seo Y, Cvetkovic C, Gapinske M, Palasz A, Dabbous H, Kong H, Pinera PP, Bashir R.
Adv Healthc Mater. 2017 May 10.
A deeper understanding of biological materials and the design principles that govern them, combined with the enabling technology of 3D printing, has given rise to the idea of "building with biology." Using these materials and tools, bio-hybrid robots or bio-bots, which adaptively sense and respond to their environment, can be manufactured. Skeletal muscle bioactuators are developed to power these bio-bots, and an approach is presented to make them dynamically responsive to changing environmental loads and robustly resilient to induced damage. Specifically, since the predominant cause of skeletal muscle loss of function is mechanical damage, the underlying mechanisms of damage are investigated in vitro, and an in vivo inspired healing strategy is developed to counteract this damage. The protocol that is developed yields complete recovery of healthy tissue functionality within two days of damage, setting the stage for a more robust, resilient, and adaptive bioactuator technology than previously demonstrated. Understanding and exploiting the adaptive response behaviors inherent within biological systems in this manner is a crucial step forward in designing bio-hybrid machines that are broadly applicable to grand engineering challenges.
Design and integration of a problem-based biofabrication course into an undergraduate biomedical engineering curriculum
Raman R, Mitchell M, Perez-Pinera P, Bashir R, DeStefano L.
J Biol Eng. 2016 Sep 21;10:10.
BACKGROUND: The rapidly evolving discipline of biological and biomedical engineering requires adaptive instructional approaches that teach students to target and solve multi-pronged and ill-structured problems at the cutting edge of scientific research. Here we present a modular approach to designing a lab-based course in the emerging field of biofabrication and biological design, leading to a final capstone design project that requires students to formulate and test a hypothesis using the scientific method.
RESULTS: Students were assessed on a range of metrics designed to evaluate the format of the course, the efficacy of the format for teaching new topics and concepts, and the depth of the contribution this course made to students training for biological engineering careers. The evaluation showed that the problem-based format of the course was well suited to teaching students how to use the scientific method to investigate and uncover the fundamental biological design rules that govern the field of biofabrication.
CONCLUSIONS: We show that this approach is an efficient and effective method of translating emergent scientific principles from the lab bench to the classroom and training the next generation of biological and biomedical engineers for careers as researchers and industry practicians.
Targeted Gene Activation Using RNA-Guided Nucleases
Brown A, Woods WS, Perez-Pinera P.
Methods Mol Biol. 2017;1468:235-50
The discovery of the prokaryotic CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR-associated) system and its adaptation for targeted manipulation of DNA in diverse species has revolutionized the field of genome engineering. In particular, the fusion of catalytically inactive Cas9 to any number of transcriptional activator domains has resulted in an array of easily customizable synthetic transcription factors that are capable of achieving robust, specific, and tunable activation of target gene expression within a wide variety of tissues and cells. This chapter describes key experimental design considerations, methods for plasmid construction, gene delivery protocols, and procedures for analysis of targeted gene activation in mammalian cell lines using CRISPR-Cas transcription factors.
Biomedical applications of gene editing
Perez-Pinera P, Chen ZY.
Hum Genet. 2016 Aug 17
Still in their infancy, the impact of these technologies in advancing biomedicine and biomedical research has been remarkable. In fact, a retrospective analysis of published gene editing research reveals some interesting trends. The majority of publications reported using gene editing tools for either basic research purposes or for generating transgenic organisms (Fig. 1). During the past 2 years alone, we also have witnessed an important increase in the total number of publications that utilize gene editing techniques to engineer therapies targeting viral infections, to perform genetic screenings, and even to develop applications related to cancer research, whereas only 2.5 % of these manuscripts actually focus on attempting to correct genetic diseases.
Synthetic biology and microbioreactor platforms for programmable production of biologics at the point-of-care
Perez-Pinera P, Han N, Cleto S, Cao J, Purcell O, Shah KA, Lee K, Ram R, Lu TK
Nat Commun. 2016 Jul 29;7:12211
Current biopharmaceutical manufacturing systems are not compatible with portable or distributed production of biologics, as they typically require the development of single biologic-producing cell lines followed by their cultivation at very large scales. Therefore, it remains challenging to treat patients in short time frames, especially in remote locations with limited infrastructure. To overcome these barriers, we developed a platform using genetically engineered Pichia pastoris strains designed to secrete multiple proteins on programmable cues in an integrated, benchtop, millilitre-scale microfluidic device. We use this platform for rapid and switchable production of two biologics from a single yeast strain as specified by the operator. Our results demonstrate selectable and near-single-dose production of these biologics in <24 h with limited infrastructure requirements. We envision that combining this system with analytical, purification and polishing technologies could lead to a small-scale, portable and fully integrated personal biomanufacturing platform that could advance disease treatment at point-of-care.
Multiplexed Targeted Genome Engineering Using a Universal Nuclease-Assisted Vector Integration System
Brown A, Woods WS, Perez-Pinera P
ACS Synth Biol. 2016 Jul 15;5(7):582-8
Engineered nucleases are capable of efficiently modifying complex genomes through introduction of targeted double-strand breaks. However, mammalian genome engineering remains limited by low efficiency of heterologous DNA integration at target sites, which is typically performed through homologous recombination, a complex, ineffective and costly process. In this study, we developed a multiplexable and universal nuclease-assisted vector integration system for rapid generation of gene knock outs using selection that does not require customized targeting vectors, thereby minimizing the cost and time frame needed for gene editing. Importantly, this system is capable of remodeling native mammalian genomes through integration of DNA, up to 50 kb, enabling rapid generation and screening of multigene knockouts from a single transfection. These results support that nuclease assisted vector integration is a robust tool for genome-scale gene editing that will facilitate diverse applications in synthetic biology and gene therapy.
In Vivo Zinc Finger Nuclease-mediated Targeted Integration of a Glucose-6-phosphatase Transgene Promotes Survival in Mice With Glycogen Storage Disease Type IA
Landau DJ, Brooks ED, Perez-Pinera P, Amarasekara H, Mefferd A, Li S, Bird A, Gersbach CA, Koeberl DD.
Mol Ther. 2016 Apr;24(4):697-706.
Glycogen storage disease type Ia (GSD Ia) is caused by glucose-6-phosphatase (G6Pase) deficiency in association with severe, life-threatening hypoglycemia that necessitates lifelong dietary therapy. Here we show that use of a zinc-finger nuclease (ZFN) targeted to the ROSA26 safe harbor locus and a ROSA26-targeting vector containing a G6PC donor transgene, both delivered with adeno-associated virus (AAV) vectors, markedly improved survival of G6Pase knockout (G6Pase-KO) mice compared with mice receiving the donor vector alone (P < 0.04). Furthermore, transgene integration has been confirmed by sequencing in the majority of the mice treated with both vectors. Targeted alleles were 4.6-fold more common in livers of mice with GSD Ia, as compared with normal littermates, at 8 months following vector administration (P < 0.02). This suggests a selective advantage for vector-transduced hepatocytes following ZFN-mediated integration of the G6Pase vector. A short-term experiment also showed that 3-month-old mice receiving the ZFN had significantly-improved biochemical correction, in comparison with mice that received the donor vector alone. These data suggest that the use of ZFNs to drive integration of G6Pase at a safe harbor locus might improve vector persistence and efficacy, and lower mortality in GSD Ia.
Engineering Synthetic Gene Circuits in Living Cells with CRISPR Technology
Jusiak B, Cleto S, Perez-Pinera P, Lu TK.
Trends Biotechnol. 2016 Jan 22. pii: S0167-7799(15)00274-7
One of the goals of synthetic biology is to build regulatory circuits that control cell behavior, for both basic research purposes and biomedical applications. The ability to build transcriptional regulatory devices depends on the availability of programmable, sequence-specific, and effective synthetic transcription factors (TFs). The prokaryotic clustered regularly interspaced short palindromic repeat (CRISPR) system, recently harnessed for transcriptional regulation in various heterologous host cells, offers unprecedented ease in designing synthetic TFs. We review how CRISPR can be used to build synthetic gene circuits and discuss recent advances in CRISPR-mediated gene regulation that offer the potential to build increasingly complex, programmable, and efficient gene circuits in the future.
Putting Non-coding RNA on Display with CRISPR
Perez-Pinera P, Jones MF, Lal A, Lu TK.
Mol Cell. 2015 Jul 16;59(2):146-8.
In a recent issue of Nature Methods, Shechner et al. (2015) reported the development of CRISPR Display (CRISP-Disp), which is a sophisticated, flexible, modular, and multiplexable platform for targeting different types of non-coding RNAs (ncRNAs) to genomic loci. CRISP-Disp will facilitate synthetic-biology applications and enable the elucidation of ncRNA functions.
Genome-wide specificity of DNA binding, gene regulation, and chromatin remodeling by TALE- and CRISPR/Cas9-based transcriptional activators
Polstein LR, Perez-Pinera P, Kocak DD, Vockley CM, Bledsoe P, Song L, Safi A, Crawford GE, Reddy TE, Gersbach CA.
Genome Res. 2015 Aug;25(8):1158-69.
Genome engineering technologies based on the CRISPR/Cas9 and TALE systems are enabling new approaches in science and biotechnology. However, the specificity of these tools in complex genomes and the role of chromatin structure in determining DNA binding are not well understood. We analyzed the genome-wide effects of TALE- and CRISPR-based transcriptional activators in human cells using ChIP-seq to assess DNA-binding specificity and RNA-seq to measure the specificity of perturbing the transcriptome. Additionally, DNase-seq was used to assess genome-wide chromatin remodeling that occurs as a result of their action. Our results show that these transcription factors are highly specific in both DNA binding and gene regulation and are able to open targeted regions of closed chromatin independent of gene activation. Collectively, these results underscore the potential for these technologies to make precise changes to gene expression for gene and cell therapies or fundamental studies of gene function.
Correction of dystrophin expression in cells from Duchenne muscular dystrophy patients through genomic excision of exon 51 by zinc finger nucleases
Ousterout DG, Kabadi AM, Thakore PI, Perez-Pinera P, Brown MT, Majoros WH, Reddy TE, Gersbach CA.
Mol Ther. 2015 Mar;23(3):523-32.
Duchenne muscular dystrophy (DMD) is caused by genetic mutations that result in the absence of dystrophin protein expression. Oligonucleotide-induced exon skipping can restore the dystrophin reading frame and protein production. However, this requires continuous drug administration and may not generate complete skipping of the targeted exon. In this study, we apply genome editing with zinc finger nucleases (ZFNs) to permanently remove essential splicing sequences in exon 51 of the dystrophin gene and thereby exclude exon 51 from the resulting dystrophin transcript. This approach can restore the dystrophin reading frame in ~13% of DMD patient mutations. Transfection of two ZFNs targeted to sites flanking the exon 51 splice acceptor into DMD patient myoblasts led to deletion of this genomic sequence. A clonal population was isolated with this deletion and following differentiation we confirmed loss of exon 51 from the dystrophin mRNA transcript and restoration of dystrophin protein expression. Furthermore, transplantation of corrected cells into immunodeficient mice resulted in human dystrophin expression localized to the sarcolemmal membrane. Finally, we quantified ZFN toxicity in human cells and mutagenesis at predicted off-target sites. This study demonstrates a powerful method to restore the dystrophin reading frame and protein expression by permanently deleting exons.
Activating human genes with zinc finger proteins, transcription activator-like effectors and CRISPR/Cas9 for gene therapy and regenerative medicine
Gersbach CA, Perez-Pinera P.
Expert Opin Ther Targets. 2014 Aug;18(8):835-9.
New technologies have recently been developed to control the expression of human genes in their native genomic context by engineering synthetic transcription factors that can be targeted to any DNA sequence. The ability to precisely regulate any gene as it occurs naturally in the genome provides a means to address a variety of diseases and disorders. This approach also circumvents some of the traditional challenges of gene therapy. In this editorial, we review the technologies that have enabled targeted human gene activation, including the engineering of transcription factors based on zinc finger proteins, transcription activator-like effectors and the CRISPR/Cas9 system. Additionally, we highlight examples in which these methods have been developed for therapeutic applications and discuss challenges and opportunities.
Multiplexed and programmable regulation of gene networks with an integrated RNA and CRISPR/Cas toolkit in human cells
Nissim L, Perli SD, Fridkin A, Perez-Pinera P, Lu TK.
Mol Cell. 2014 May 22;54(4):698-710.
RNA-based regulation and CRISPR/Cas transcription factors (CRISPR-TFs) have the potential to be integrated for the tunable modulation of gene networks. A major limitation of this methodology is that guide RNAs (gRNAs) for CRISPR-TFs can only be expressed from RNA polymerase III promoters in human cells, limiting their use for conditional gene regulation. We present new strategies that enable expression of functional gRNAs from RNA polymerase II promoters and multiplexed production of proteins and gRNAs from a single transcript in human cells. We use multiple RNA regulatory strategies, including RNA-triple-helix structures, introns, microRNAs, and ribozymes, with Cas9-based CRISPR-TFs and Cas6/Csy4-based RNA processing. Using these tools, we efficiently modulate endogenous promoters and implement tunable synthetic circuits, including multistage cascades and RNA-dependent networks that can be rewired with Csy4 to achieve complex behaviors. This toolkit can be used for programming scalable gene circuits and perturbing endogenous networks for biology, therapeutic, and synthetic biology applications.
Scaffold-mediated lentiviral transduction for functional tissue engineering of cartilage
Brunger JM, Huynh NP, Guenther CM, Perez-Pinera P, Moutos FT, Sanchez-Adams J, Gersbach CA, Guilak F.
Proc Natl Acad Sci U S A. 2014 Mar 4;111(9):E798-806.
The ability to develop tissue constructs with matrix composition and biomechanical properties that promote rapid tissue repair or regeneration remains an enduring challenge in musculoskeletal engineering. Current approaches require extensive cell manipulation ex vivo, using exogenous growth factors to drive tissue-specific differentiation, matrix accumulation, and mechanical properties, thus limiting their potential clinical utility. The ability to induce and maintain differentiation of stem cells in situ could bypass these steps and enhance the success of engineering approaches for tissue regeneration. The goal of this study was to generate a self-contained bioactive scaffold capable of mediating stem cell differentiation and formation of a cartilaginous extracellular matrix (ECM) using a lentivirus-based method. We first showed that poly-L-lysine could immobilize lentivirus to poly(ε-caprolactone) films and facilitate human mesenchymal stem cell (hMSC) transduction. We then demonstrated that scaffold-mediated gene delivery of transforming growth factor β3 (TGF-β3), using a 3D woven poly(ε-caprolactone) scaffold, induced robust cartilaginous ECM formation by hMSCs. Chondrogenesis induced by scaffold-mediated gene delivery was as effective as traditional differentiation protocols involving medium supplementation with TGF-β3, as assessed by gene expression, biochemical, and biomechanical analyses. Using lentiviral vectors immobilized on a biomechanically functional scaffold, we have developed a system to achieve sustained transgene expression and ECM formation by hMSCs. This method opens new avenues in the development of bioactive implants that circumvent the need for ex vivo tissue generation by enabling the long-term goal of in situ tissue engineering.
RNA-guided gene activation by CRISPR-Cas9-based transcription factors
Perez-Pinera P, Kocak DD, Vockley CM, Adler AF, Kabadi AM, Polstein LR, Thakore PI, Glass KA, Ousterout DG, Leong KW, Guilak F, Crawford GE, Reddy TE, Gersbach CA.
Nat Methods. 2013 Oct;10(10):973-6.
Technologies for engineering synthetic transcription factors have enabled many advances in medical and scientific research. In contrast to existing methods based on engineering of DNA-binding proteins, we created a Cas9-based transactivator that is targeted to DNA sequences by guide RNA molecules. Coexpression of this transactivator and combinations of guide RNAs in human cells induced specific expression of endogenous target genes, demonstrating a simple and versatile approach for RNA-guided gene activation.
Reading frame correction by targeted genome editing restores dystrophin expression in cells from Duchenne muscular dystrophy patients
Ousterout DG, Perez-Pinera P, Thakore PI, Kabadi AM, Brown MT, Qin X, Fedrigo O, Mouly V, Tremblay JP, Gersbach CA.
Mol Ther. 2013 Sep;21(9):1718-26.
Genome editing with engineered nucleases has recently emerged as an approach to correct genetic mutations by enhancing homologous recombination with a DNA repair template. However, many genetic diseases, such as Duchenne muscular dystrophy (DMD), can be treated simply by correcting a disrupted reading frame. We show that genome editing with transcription activator-like effector nucleases (TALENs), without a repair template, can efficiently correct the reading frame and restore the expression of a functional dystrophin protein that is mutated in DMD. TALENs were engineered to mediate highly efficient gene editing at exon 51 of the dystrophin gene. This led to restoration of dystrophin protein expression in cells from Duchenne patients, including skeletal myoblasts and dermal fibroblasts that were reprogrammed to the myogenic lineage by MyoD. Finally, exome sequencing of cells with targeted modifications of the dystrophin locus showed no TALEN-mediated off-target changes to the protein-coding regions of the genome, as predicted by in silico target site analysis. This strategy integrates the rapid and robust assembly of active TALENs with an efficient gene-editing method for the correction of genetic diseases caused by mutations in non-essential coding regions that cause frameshifts or premature stop codons.
Synergistic and tunable human gene activation by combinations of synthetic transcription factors
Perez-Pinera P, Ousterout DG, Brunger JM, Farin AM, Glass KA, Guilak F, Crawford GE, Hartemink AJ, Gersbach CA.
Nat Methods. 2013 Mar;10(3):239-42.
Mammalian genes are regulated by the cooperative and synergistic actions of many transcription factors. In this study we recapitulate this complex regulation in human cells by targeting endogenous gene promoters, including regions of closed chromatin upstream of silenced genes, with combinations of engineered transcription activator-like effectors (TALEs). These combinations of TALE transcription factors induced substantial gene activation and allowed tuning of gene expression levels that will broadly enable synthetic biology, gene therapy and biotechnology.
Advances in targeted genome editing
Perez-Pinera P, Ousterout DG, Gersbach CA.
Curr Opin Chem Biol. 2012 Aug;16(3-4):268-77.
New technologies have recently emerged that enable targeted editing of genomes in diverse systems. This includes precise manipulation of gene sequences in their natural chromosomal context and addition of transgenes to specific genomic loci. This progress has been facilitated by advances in engineering targeted nucleases with programmable, site-specific DNA-binding domains, including zinc finger proteins and transcription activator-like effectors (TALEs). Recent improvements have enhanced nuclease performance, accelerated nuclease assembly, and lowered the cost of genome editing. These advances are driving new approaches to many areas of biotechnology, including biopharmaceutical production, agriculture, creation of transgenic organisms and cell lines, and studies of genome structure, regulation, and function. Genome editing is also being investigated in preclinical and clinical gene therapies for many diseases.
Gene targeting to the ROSA26 locus directed by engineered zinc finger nucleases
Perez-Pinera P, Ousterout DG, Brown MT, Gersbach CA.
Nucleic Acids Res. 2012 Apr;40(8):3741-52.
Targeted gene addition to mammalian genomes is central to biotechnology, basic research and gene therapy. For example, gene targeting to the ROSA26 locus by homologous recombination in embryonic stem cells is commonly used for mouse transgenesis to achieve ubiquitous and persistent transgene expression. However, conventional methods are not readily adaptable to gene targeting in other cell types. The emerging zinc finger nuclease (ZFN) technology facilitates gene targeting in diverse species and cell types, but an optimal strategy for engineering highly active ZFNs is still unclear. We used a modular assembly approach to build ZFNs that target the ROSA26 locus. ZFN activity was dependent on the number of modules in each zinc finger array. The ZFNs were active in a variety of cell types in a time- and dose-dependent manner. The ZFNs directed gene addition to the ROSA26 locus, which enhanced the level of sustained gene expression, the uniformity of gene expression within clonal cell populations and the reproducibility of gene expression between clones. These ZFNs are a promising resource for cell engineering, mouse transgenesis and pre-clinical gene therapy studies. Furthermore, this characterization of the modular assembly method provides general insights into the implementation of the ZFN technology.
Pleiotrophin expression during odontogenesis
Erlandsen H, Ames JE, Tamkenath A, Mamaeva O, Stidham K, Wilson ME, Perez-Pinera P, Deuel TF, Macdougall M.J
Histochem Cytochem. 2012 May;60(5):366-75.
Pleiotrophin (PTN) is an extracellular matrix-associated growth factor and chemokine expressed in mesodermal and ectodermal cells. It plays an important role in osteoblast recruitment and differentiation. There is limited information currently available about PTN expression during odontoblast differentiation and tooth formation, and thus the authors aimed to establish the spatiotemporal expression pattern of PTN during mouse odontogenesis. Immortalized mouse dental pulp (MD10-D3, MD10-A11) and odontoblast-like (M06-G3) and ameloblast-like (EOE-3M) cell lines were grown and samples prepared for immunocytochemistry, Western blot, and conventional and quantitative PCR analysis. Effects of BMP2, BMP4, and BMP7 treatment on PTN expression in odontoblast-like M06-G3 cells were tested by quantitative PCR. Finally, immunohistochemistry of sectioned mice mandibles and maxillaries at developmental stages E16, E18, P1, P6, P10, and P28 was performed. The experiments showed that PTN, at both the mRNA and protein level, was expressed in all tested epithelial and mesenchymal dental cell lines and that the level of PTN mRNA was influenced differentially by the bone morphogenetic proteins. The authors observed initial expression of PTN in the inner enamel epithelium with prolonged expression in the ameloblasts and odontoblasts throughout their stages of maturation and strong expression in the terminally differentiated and enamel matrix-secreting ameloblasts and odontoblasts of the adult mouse incisors and molars.
Clinical implication of Meissner`s corpuscles
Vega JA, López-Muñiz A, Calavia MG, García-Suárez O, Cobo J, Otero J, Arias-Carrión O, Pérez-Piñera P, Menéndez-González M.
CNS Neurol Disord Drug Targets. 2012 Nov 1;11(7):856-68.
During the last decade skin biopsy has been confirmed as a tool to provide diagnostic information on some peripheral neuropathies. Most studies were focused on intraepithelial nerve fibers and few studies have investigated large myelinated fibers or whether corpuscles in human skin change quantitatively or qualitatively in pathologies of the peripheral or central nervous system. The main objective of this article is to provide a comprehensive review of Meissner's corpuscles including their distribution, density and age changes, development, molecular composition, cellular anatomy and physiology. We also describe their involvement in several pathologies and suggest including this dermal structure in the routine study of skin biopsies, looking for changes to be used as potential markers for several disorders. Finally the article draws the main aspects of how to study Meissner's corpuscles in skin biopsies and gives a view on future perspectives for implementing their use in clinical practice.
Immunotherapy for Alzheimer's disease: rational basis in ongoing clinical trials
Menéndez-González M, Pérez-Piñera P, Martínez-Rivera M, Muñiz AL, Vega JA.
Curr Pharm Des. 2011;17(5):508-20.
Amyloid-β (Aβ) immunotherapy has recently begun to gain considerable attention as a potentially promising therapeutic approach to reducing the levels of Aβ in the Central Nervous System (CNS) of patients with Alzheimer's Disease (AD). Despite extensive preclinical evidence showing that immunization with Aβ(1-42) peptide can prevent or reverse the development of the neuropathological hallmarks of AD, in 2002, the clinical trial of AN-1792, the first trial involving an AD vaccine, was discontinued at Phase II when a subset of patients immunized with Aβ(1-42) developed meningoencephalitis, thereby making it necessary to take a more refined and strategic approach towards developing novel Aβ immunotherapy strategies by first constructing a safe and effective vaccine. This review describes the rational basis in modern clinical trials that have been designed to overcome the many challenges and known hurdles inherent to the search for effective AD immunotherapies. The precise delimitation of the most appropriate targets for AD vaccination remains a major point of discussion and emphasizes the need to target antigens in proteins involved in the early steps of the amyloid cascade. Other obstacles that have been clearly defined include the need to avoid unwanted anti-Aβ/APP Th1 immune responses, the need to achieve adequate responses to vaccination in the elderly and the need for precise monitoring. Novel strategies have been implemented to overcome these problems including the use of N-terminal peptides as antigens, the development of DNA based epitope vaccines and vaccines based on passive immunotherapy, recruitment of patients at earlier stages with support of novel biomarkers, the use of new adjuvants, the use of foreign T cell epitopes and viral-like particles and adopting new efficacy endpoints. These strategies are currently being tested in over 10,000 patients enrolled in one of the more than 40 ongoing clinical trials, most of which are expected to report final results within two years.
Human odontoblasts express transient receptor protein and acid-sensing ion channel mechanosensor proteins
Solé-Magdalena A, Revuelta EG, Menénez-Díaz I, Calavia MG, Cobo T, García-Suárez O, Pérez-Piñera P, De Carlos F, Cobo J, Vega JA.
Microsc Res Tech. 2011 May;74(5):457-63.
Diverse proteins of the denegerin/epithelial sodium channel (DEG/ENa(+) C) superfamily, in particular those belonging to the acid-sensing ion channel (ASIC) family, as well as some members of the transient receptor protein (TRP) channel, function as mechanosensors or may be required for mechanosensation in a diverse range of species and cell types. Therefore, we investigated the putative mechanosensitive function of human odontoblasts using immunohistochemistry to detect ENa(+) C subunits (α, β, and γ) and ASIC (1, 2, 3, and 4) proteins, as well as TRPV4, in these cells. Positive and specific immunoreactivity in the odontoblast soma and/or processes was detected for all proteins studied except α-ENa(+) C. The intensity of immunostaining was high for β-ENa(+) C and ASIC2, whereas it was low for ASIC1, ASIC3, γ-ENa(+) C, and TRPV4, being absent for α-ENa(+) C and ASIC4. These results suggest that human odontoblasts in situ express proteins related to mechanosensitive channels that probably participate in the mechanisms involved in teeth sensory transmission.
Expression and cell localization of brain-derived neurotrophic factor and TrkB during zebrafish retinal development
Germanà A, Sánchez-Ramos C, Guerrera MC, Calavia MG, Navarro M, Zichichi R, García-Suárez O, Pérez-Piñera P, Vega JA.
J Anat. 2010 Sep;217(3):214-22.
Brain-derived neurotrophic factor (BDNF) signaling through TrkB regulates different aspects of neuronal development, including survival, axonal and dendritic growth, and synapse formation. Despite recent advances in our understanding of the functional significance of BDNF and TrkB in the retina, the cell types in the retina that express BDNF and TrkB, and the variations in their levels of expression during development, remain poorly defined. The goal of the present study is to determine the age-dependent changes in the levels of expression and localization of BDNF and TrkB in the zebrafish retina. Zebrafish retinas from 10 days post-fertilization (dpf) to 180 dpf were used to perform PCR, Western blot and immunohistochemistry. Both BDNF and TrkB mRNAs, and BDNF and full-length TrkB proteins were detected at all ages sampled. The localization of these proteins in the retina was very similar at all time points studied. BDNF immunoreactivity was found in the outer nuclear layer, the outer plexiform layer and the inner plexiform layer, whereas TrkB immunoreactivity was observed in the inner plexiform layer and, to a lesser extent, in the ganglion cell layer. These results demonstrate that the pattern of expression of BDNF and TrkB in the retina of zebrafish remains unchanged during postembryonic development and adult life. Because TrkB expression in retina did not change with age, cells expressing TrkB may potentially be able to respond during the entire lifespan of zebrafish to BDNF either exogenously administered or endogenously produced, acting through paracrine mechanisms.
Differential localization of Acid-sensing ion channels 1 and 2 in human cutaneus pacinian corpuscles
Calavia MG, Montaño JA, García-Suárez O, Feito J, Guervós MA, Germanà A, Del Valle M, Pérez-Piñera P, Cobo J, Vega JA.
Cell Mol Neurobiol. 2010 Aug;30(6):841-8.
Acid-sensing ion channels (ASICs) are the members of the degenerin/epithelial sodium channel (Deg/ENaC) superfamily which mediate different sensory modalities including mechanosensation. ASICs have been detected in mechanosensory neurons as well as in peripheral mechanoreceptors. We now investigated the distribution of ASIC1, ASIC2, and ASIC3 proteins in human cutaneous Pacinian corpuscles using immunohistochemistry and laser confocal-scanner microscopy. We detected different patterns of expression of these proteins within Pacinian corpuscles. ASIC1 was detected in the central axon co-expressed with RT-97 protein, ASIC2 was expressed by the lamellar cells of the inner core co-localized with S100 protein, and ASIC3 was absent. These results demonstrate for the first time the differential distribution of ASIC1 and ASIC2 in human rapidly adapting low-threshold mechanoreceptors, and suggest specific roles of both proteins in mechanotransduction.
The neurotrophic factor pleiotrophin modulates amphetamine-seeking behaviour and amphetamine-induced neurotoxic effects: evidence from pleiotrophin knockout mice
Gramage E, Putelli A, Polanco MJ, González-Martín C, Ezquerra L, Alguacil LF, Pérez-Pinera P, Deuel TF, Herradón G.
Addict Biol. 2010 Oct;15(4):403-12.
Pleiotrophin (PTN), a neurotrophic factor with important roles in survival and differentiation of dopaminergic neurons, is up-regulated in the nucleus accumbens after amphetamine administration suggesting that PTN could modulate amphetamine-induced pharmacological or neuroadaptative effects. To test this hypothesis, we have studied the effects of amphetamine administration in PTN genetically deficient (PTN -/-) and wild type (WT, +/+) mice. In conditioning studies, we found that amphetamine induces conditioned place preference in both PTN -/- and WT (+/+) mice. When these mice were re-evaluated after a 5-day period without amphetamine administration, we found that WT (+/+) mice did not exhibit amphetamine-seeking behaviour, whereas, PTN -/- mice still showed a robust drug-seeking behaviour. In immunohystochemistry studies, we found that amphetamine (10 mg/kg, four times, every 2 hours) causes a significant increase of glial fibrillary acidic protein positive cells in the striatum of amphetamine-treated PTN -/- mice compared with WT mice 4 days after last administration of the drug, suggesting an enhanced amphetamine-induced astrocytosis in the absence of endogenous PTN. Interestingly, we found in concomitant in vitro studies that PTN (3 µM) limits amphetamine (1 mM)-induced loss of viability of PC12 cell cultures, effect that could be related to the ability of PTN to induce the phosphorylation of Akt and ERK1/2. To test this possibility, we used specific Akt and ERK1/2 inhibitors uncovering for the first time that PTN-induced protective effects against amphetamine-induced toxicity in PC12 cells are mediated by the ERK1/2 signalling pathway. The data suggest an important role of PTN to limit amphetamine-induced neurotoxic and rewarding effects.
Immunohistochemical profile of human pancreatic pacinian corpuscles
García-Suárez O, Calavia MG, Pérez-Moltó FJ, Alvarez-Abad C, Pérez-Piñera P, Cobo JM, Vega JA.
Pancreas. 2010 Apr;39(3):403-10.
To analyze the immunohistochemical profile of the human pancreatic pacinian corpuscles in comparison with that of the cutaneous pacinian corpuscles. In addition, we studied a Pacinilike corpuscle found in the adventitia of a pancreatic artery.
We used immunohistochemistry to detect specific antigens for corpuscular constituents, specific antibodies for the identification of Adelta- and C-sensory fibers and for the detection of several growth factor receptors, and some members of the degenerin/epithelial Na channel superfamily of proteins.
Approximately 62% of pancreatic pacinian corpuscles have 2 to 10 axonic profiles each enclosed by its own inner core: 1 or 2 of these axonic profiles displayed RT-97 immunoreactivity (specific marker of mechanical axons). The cutaneous pacinian corpuscles showed not more than 2 axonic profiles with identical immunohistochemical characteristics. The expression of glial fibrillary acidic protein, epithelial membrane antigen, and tyrosine receptor kinase B was different between pancreatic and cutaneous pacinian corpuscles; the pattern of distribution of degenerin/epithelial Na channel proteins was identical in both cases. The arterial Pacinilike corpuscles displayed a specific immunohistochemical profile.
Pancreatic pacinian corpuscles slightly differ from the cutaneous ones, and these differences could be related to topography, growth factor requirements, or function of pacinian corpuscles in the pancreas.
The lamellar cells in human Meissner corpuscles express TrkB
Calavia MG, Feito J, López-Iglesias L, de Carlos F, García-Suarez O, Pérez-Piñera P, Cobo J, Vega JA.
Neurosci Lett. 2010 Jan 4;468(2):106-9.
Cutaneous Meissner corpuscles depend for development and survival exclusively on the NT system TrkB/BDNF/NT-4 unlike other types of sensory corpuscles and nerve endings, which have very complex neuronal and growth factor dependence. However, the pattern of expression of TrkB in human Meissner corpuscles is not known. The experiments in these studies were designed to pursue further findings that suggest that BDNF and NT-4 have critical roles in the development and maintenance of Meissner corpuscles by analyzing the pattern of expression of TrkB, their high-affinity receptor, in human glabrous skin. These experiments showed that TrkB is expressed in different patterns by the lamellar cells of Meissner corpuscles and not by the axon. The studies also show that while the percentage of Meissner corpuscles that express TrkB remains constant from birth till 50-year old cases, it decreases approximately 3-fold in subjects older than 50 years. These results are important since the study of Meissner corpuscles from cutaneous biopsies to diagnose some neurological diseases has rapidly become of high interest and therefore the proteins expressed in these corpuscles are potential diagnostic tools.
Development and neuronal dependence of cutaneous sensory nerve formations: Lessons from neurotrophins
Montaño JA, Pérez-Piñera P, García-Suárez O, Cobo J, Vega JA.
Microsc Res Tech. 2010 May;73(5):513-29.
Null mutations of genes from the NGF family of NTs and their receptors (NTRs) lead to loss/reduction of specific neurons in sensory ganglia; conversely, cutaneous overexpression of NTs results in skin hyperinnervation and increase or no changes in the number of sensory neurons innervating the skin. These neuronal changes are paralleled with loss of specific types of sensory nerve formations in the skin. Therefore, mice carrying mutations in NT or NTR genes represent an ideal model to identify the neuronal dependence of each type of cutaneous sensory nerve ending from a concrete subtype of sensory neuron, since the development, maintenance, and structural integrity of sensory nerve formations depend upon sensory neurons. Results obtained from these mouse strains suggest that TrkA positive neurons are connected to intraepithelial nerve fibers and other sensory nerve formations depending from C and Adelta nerve fibers; the neurons expressing TrkB and responding to BDNF and NT-4 innervate Meissner corpuscles, a subpopulation of Merkell cells, some mechanoreceptors of the piloneural complex, and the Ruffini's corpuscles; finally, a subpopulation of neurons, which are responsive to NT-3, support postnatal survival of some intraepithelial nerve fibers and Merkel cells in addition to the muscle mechanoreceptors. On the other hand, changes in NTs and NTRs affect the structure of non-nervous structures of the skin and are at the basis of several cutaneous pathologies. This review is an update about the role of NTs and NTRs in the maintenance of normal cutaneous innervation and maintenance of skin integrity.
The expression of ENa(+)C and ASIC2 proteins in Pacinian corpuscles is differently regulated by TrkB and its ligands BDNF and NT-4
Montaño JA, Calavia MG, García-Suárez O, Suarez-Quintanilla JA, Gálvez A, Pérez-Piñera P, Cobo J, Vega JA.
Neurosci Lett. 2009 Oct 2;463(2):114-8.
Pacinian corpuscles are innervated by large myelinated Aalpha-beta axons from the large- and intermediate-sized sensory neurons of dorsal root ganglia. These neurons express different members of the degenerin/epithelial Na(+) channel (DEG/ENa(+)C) superfamily of proteins with putative mechanosensory properties, whose expression is regulated by the TrkB-BDNF system. Thus, we hypothesized that BDNF and/or NT-4 signalling through activation of TrkB may regulate the expression of molecules supposed to be necessary for the mechanosensory function of Pacinian corpuscles. To test this hypothesis we analyzed the expression and distribution of ENa(+)C subunits and acid-sensing ion channel 2 (ASIC2) in Pacinian corpuscles from 25 days old mice deficient in TrkB, BDNF and NT-4. Pacinian corpuscles in these animals are normal in number, structure, and expression of several immunohistochemical markers. Using immunohistochemistry we observed that the beta-ENa(+)C and gamma-ENa(+)C subunits, but not the alpha-ENa(+)C subunit, were expressed in wild-type animals, and they were always found in the central axon. ASIC2 immunoreactivity was found in both the central axon and the inner core cells. The absence of TrkB or BDNF abolished expression of beta-ENa(+)C and ASIC2, whereas expression of gamma-ENa(+)C did not change. Expression of beta-ENa(+)C and gamma-ENa(+)C subunits in NT-4 deficient mice was found in the axons but also in the inner core cells whereas levels of expression of ASIC2 were increased in these animals. This study suggests that expression in Pacianian corpuscles of some potential mechanosensory proteins is regulated by BDNF, NT-4 and TrkB.
TrkB is necessary for the normal development of the lung
García-Suárez O, Pérez-Pinera P, Laurà R, Germana A, Esteban I, Cabo R, Silos-Santiago I, Cobo JL, Vega JA.
Respir Physiol Neurobiol. 2009 Jul 31;167(3):281-91.
Normal development of the lung requires coordinated activation of cascades of signaling pathways initiated by growth factors signaling through their receptors. TrkB and its ligands, brain-derived neurotrophic factor (BDNF) and neurotrophin-4, belong to the neurotrophin family of growth factors, which are expressed in a large variety of non-neuronal tissues including the lung. Aberrant neurotrophin signaling underlies the pathogenesis of several lung-related pathologies, including asthma and lung cancer, however, little is known about the role of neurotrophins in the embryonic development of the lung. To fill this gap in knowledge, we analyzed the pattern of TrkB expression in the murine lung and we observed that TrkB is expressed in alveolar macrophages, type II pneumocytes, neuroepithelial bodies and nerves. Analysis of the structure of lung from mice deficient in TrkB revealed that absence of TrkB signaling results in thinner bronchial epithelium and apparent larger air space, and, more importantly, lack of neuroepithelial bodies, an important reduction in the density of nerve fibres in the bronchial smooth muscle, submucous plexus in bronchioles, and pulmonary artery walls. These findings suggest TrkB is essential for the normal development of the lung and the nervous system in the lung.
Enteric glial cells express full-length TrkB and depend on TrkB expression for normal development
Levanti MB, Esteban I, Ciriaco E, Pérez-Piñera P, Cabo R, García-Suarez O, Pardo B, Silos-Santiago I, Cobo J, Vega JA.
Neurosci Lett. 2009 Apr 17;454(1):16-21.
The embryonic development of the enteric nervous system (ENS) from neural crest precursor cells requires neurotrophic signaling. Neurotrophins (NTs) are a family of growth factors that bind Trk receptors to signal diverse functions, including development and maintenance of different cell populations in the peripheral nervous system. In this study we investigated the expression and cell localization of TrkB, the high affinity receptor for brain-derived neurotrophic factor and NT-4, in the murine ENS using Western blot and immunohistochemistry. The results demonstrate that enteric glial cells within the ENS express full-length TrkB at all stages tested. The ENS of TrkB deficient mice have reduced expression of glial cell markers, and a disarrangement of glial cells and the plexular neuropil. These results strongly suggest TrkB has essential roles in the normal development and maintenance of glial cells in the ENS.
Pleiotrophin inhibits hippocampal long-term potentiation: a role of pleiotrophin in learning and memory
del Olmo N, Gramage E, Alguacil LF, Pérez-Pinera P, Deuel TF, Herradón G.
Growth Factors. 2009 Jun;27(3):189-94.
Pleiotrophin (PTN) is a growth factor that has been shown to be involved in hippocampal synaptic plasticity and learning. To further understand the involvement of PTN in memory processes, we performed in vitro electrophysiological studies in PTN-stimulated CA1 from rat hippocampal slices combined with the behavioural testing of PTN deficient (PTN - / - ) mice. We found that PTN inhibited hippocampal long-term potentiation (LTP) induced by high-frequency stimulation (HFS) consisted in three trains of 100 Hz separated by 20 s. To test the possibility that PTN might be involved in behavioural memory processes, we tested the learning behaviour of PTN - / - mice using the Y-maze test. We did not observe significant differences in recognition memory between PTN - / - and Wild Type (WT) mice when a 30 min-interval intertrial (ITI) was used in the Y-maze test. However, whereas WT mice showed disruption of recognition memory using a 60 min-ITI, PTN - / - mice maintained the recognition memory. The data demonstrate that PTN inhibits hippocampal LTP in vitro and might play a role in memory processes in vivo.
Pleiotrophin produced by multiple myeloma induces transdifferentiation of monocytes into vascular endothelial cells: a novel mechanism of tumor-induced vasculogenesis
Chen H, Campbell RA, Chang Y, Li M, Wang CS, Li J, Sanchez E, Share M, Steinberg J, Berenson A, Shalitin D, Zeng Z, Gui D, Perez-Pinera P, Berenson RJ, Said J, Bonavida B, Deuel TF, Berenson JR.
Blood. 2009 Feb 26;113(9):1992-2002.
Enhanced angiogenesis is a hallmark of cancer. Pleiotrophin (PTN) is an angiogenic factor that is produced by many different human cancers and stimulates tumor blood vessel formation when it is expressed in malignant cancer cells. Recent studies show that monocytes may give rise to vascular endothelium. In these studies, we show that PTN combined with macrophage colony-stimulating factor (M-CSF) induces expression of vascular endothelial cell (VEC) genes and proteins in human monocyte cell lines and monocytes from human peripheral blood (PB). Monocytes induce VEC gene expression and develop tube-like structures when they are exposed to serum or cultured with bone marrow (BM) from patients with multiple myeloma (MM) that express PTN, effects specifically blocked with antiPTN antibodies. When coinjected with human MM cells into severe combined immunodeficient (SCID) mice, green fluorescent protein (GFP)-marked human monocytes were found incorporated into tumor blood vessels and expressed human VEC protein markers and genes that were blocked by anti-PTN antibody. Our results suggest that vasculogenesis in human MM may develop from tumoral production of PTN, which orchestrates the transdifferentiation of monocytes into VECs.
Plasmatic level of neurosin predicts outcome of mild cognitive impairment
Menendez-Gonzalez M, Castro-Santos P, Calatayud MT, Perez-Piñera P, Ribacoba R, Martinez-Rivera M, Gutierrez C, Lopez-Muñiz A, Suarez A.
Int Arch Med. 2008 Jul 11;1(1):11.
Mild Cognitive Impairment (MCI) is a disorder considered to be a transitional stage from health to dementia. Diagnosis of dementias at these early stages is always troublesome because the pathophysiologic events leading to dementia precede clinical symptoms. Thus, the development of biomarkers that can be used to support the diagnosis of dementias at early stages is rapidly becoming a high priority. We have recently reported the value of measuring plasmatic levels of neurosin in the diagnosis of Alzheimer's disease (AD). The aim of this study is to determine whether measuring plasmatic concentration of neurosin is a valuable test to predict progression of MCI.
Plasmatic neurosin concentrations were measured in 68 MCI patients and 70 controls subjects. Blood samples were obtained at the beginning of the study. Sixty six patients diagnosed with MCI were observed for 18 months. In 36 patients a second blood sample was obtained at the endpoint.
The mean value of plasmatic neurosin concentration differs significantly between MCI patients who converted to Dementia with vascular component, those who converted to AD, or those who remained at MCI stage. The relative risk of developing Dementia with vascular component when neurosin levels are higher than 5.25 ng/ml is 13 while the relative risk of developing mild AD when neurosin levels are lower than 5.25 ng/ml is 2. Increases in the levels of neurosin indicate progression to Dementia with vascular component.
The measurement of plasmatic neurosin level in patients diagnosed with MCI may predict conversion from MCI to Dementia with vascular component. A single measurement is also valuable to estimate the risk of developing AD and Dementia with vascular component. Finally, repeated measurement of plasmatic neurosin might be a useful test to predict outcome in patients with MCI.
Value of measuring plasmatic levels of neurosin in the diagnosis of Alzheimer's disease
Menendez-Gonzalez M, Castro-Santos P, Suarez A, Calatayud MT, Perez-Pinera P, Martinez M, Ribacoba R, Gutierrez C.
J Alzheimers Dis. 2008 May;14(1):59-67.
The search for molecular biomarkers for diagnosing and classifying dementias is becoming a high priority need. Neurosin (Kallikrein 6, hk6) is one molecule with promising preliminary results since its levels in brain tissue, cerebrospinal fluid and blood have been found to be abnormal in Alzheimer's disease (AD). In this study, we measured plasmatic levels of neurosin in healthy individuals and patients with cognitive symptoms independently of what the final diagnosis was. We collected plasma samples from 228 controls and 447 patients finally diagnosed with either AD, Mild Cognitive Impairment, Dementia with Lewy Bodies or Parkinson-Dementia, Frontotemporal Dementia, Huntington's disease, Primary Progressive Aphasia, Corticobasal degeneration, Creutzfeldt-Jakob's disease or Pseudodementia. We found that plasmatic levels of neurosin increase with age in healthy individuals and decrease in patients with AD. Plasmatic levels of neurosin differ significantly between AD and Vascular Dementia, Pseudodementia and the control group. Analyses comparing any other form of neurodegenerative dementia to the AD group did not show significant differences. In conclusion, measurement of plasmatic levels of neurosin is useful to distinguish AD patients from subjects without neurodegenerative dementia (either Pseudodementia, Vascular Dementia or controls) although it is not useful to distinguish among neurodegenerative dementias.
Pleiotrophin, a multifunctional angiogenic factor: mechanisms and pathways in normal and pathological angiogenesis
Perez-Pinera P, Berenson JR, Deuel TF.
Curr Opin Hematol. 2008 May;15(3):210-4.
PURPOSE OF REVIEW:
This study seeks to integrate recent studies that identify new critical mechanisms through which the 136 amino acid secreted heparin-binding cytokine pleiotrophin (PTN, Ptn) stimulates both normal and pathological angiogenesis.
Pleiotrophin is directly angiogenic; it initiates an angiogenic switch in different cancer models in vivo. It acts as an angiogenic factor through multiple mechanisms that include a unique signaling pathway that activates newly identified downstream tyrosine kinases through a unique mechanism, an interaction with endothelial cells to initiate proliferation, migration, and tube formation, the regulation of basic fibroblast growth factor and vascular endothelial growth factor signaling, the remodeling of the stromal microenvironment, and induction of transdifferentiation of monocytes into endothelial cells. Recently also, domains of PTN that stimulate angiogenesis and peptides that function to inhibit PTN signaling have been identified.
Recent studies have identified new mechanisms dependent on activation of the PTN signaling pathway that regulate angiogenesis and new targets to use PTN to both stimulate angiogenesis and block its activity to control pathological angiogenesis.
Characterization of sensory deficits in TrkB knockout mice
Perez-Pinera P, García-Suarez O, Germanà A, Díaz-Esnal B, de Carlos F, Silos-Santiago I, del Valle ME, Cobo J, Vega JA.
Neurosci Lett. 2008 Mar 5;433(1):43-7.
The sensory deficit in TrkB deficient mice was evaluated by counting the neuronal loss in lumbar dorsal root ganglia (DRG), the absence of sensory receptors (cutaneous--associated to the hairy and glabrous skin - muscular and articular), and the percentage and size of the neurocalcin-positive DRG neurons (a calcium-binding protein which labels proprioceptive and mechanoceptive neurons). Mice lacking TrkB lost 32% of neurons, corresponding to the intermediate-sized and neurocalcin-positive ones. This neuronal lost was accomplished by the absence of Meissner corpuscles, and reduction of hair follicle-associated sensory nerve endings and Merkel cells. The mutation was without effect on Pacinian corpuscles, Golgi's organs and muscle spindles. Present results further characterize the sensory deficit of the TrkB-/- mice demonstrating that the intermediate-sized neurons in lumbar DRG, as well as the cutaneous rapidly and slowly adapting sensory receptors connected to them, are under the control of TrkB for survival and differentiation. This study might serve as a baseline for future studies in experimentally induced neuropathies affecting TrkB positive DRG neurons and their peripheral targets, and to use TrkB ligands in the treatment of neuropathies in which cutaneous mechanoreceptors are primarily involved.
Pleiotrophin, a multifunctional tumor promoter through induction of tumor angiogenesis, remodeling of the tumor microenvironment, and activation of stromal fibroblasts
Perez-Pinera P, Chang Y, Deuel TF.
Cell Cycle. 2007 Dec 1;6(23):2877-83.
Pleiotrophin (PTN, Ptn) is a widely expressed, developmentally regulated 136 amino acid secreted heparin-binding cytokine. It signals through a unique signaling pathway; the PTN receptor is the transmembrane receptor protein tyrosine phosphatase (RPTP)beta/zeta. RPTPbeta/zeta is inactivated by PTN, which leads to increased tyrosine phosphorylation of the downstream targets of the PTN/RPTPbeta/zeta signaling pathway. Pleiotrophin gene expression is found in cells in early differentiation during different developmental periods. It is upregulated in cells with an early differentiation phenotype in wound repair. The Ptn gene also is a proto-oncogene; PTN is expressed in human tumor cells, and, in cell lines derived from human tumors that express Ptn, Ptn expression is constitutive and thus "inappropriate". Importantly, properties of different cells induced by PTN in PTN-stimulated cells are strikingly similar to properties of highly malignant cells. Furthermore, transformed cells into which Ptn is introduced undergo "switches" to malignant cells of higher malignancy with properties that are strikingly similar to properties of PTN-stimulated cells. These unique features of PTN support the conclusion that constitutive PTN signaling in malignant cells that inappropriately express Ptn functions as a potent tumor promoter. Recently, in confirmation, Ptn targeted by the mouse mammary tumor virus (MMTV) promoter in a transgenic mouse model was found to promote breast cancers to a more aggressive breast cancer cell phenotype that morphologically closely resembles scirrhous carcinoma in human; in addition, it promoted a striking increase in tumor angiogenesis and a remarkable degree of remodeling of the micro-environment. Pleiotrophin thus regulates both different normal and pathological functions; collectively, the different studies have uncovered the unique ability of a single cytokine PTN, which signals through the unique PTN/RPTPbeta/zeta signaling pathway, to induce the many properties associated with tumor promotion in the malignant cells that constitutively express Ptn and in their microenvironment.
The receptor protein tyrosine phosphatase (RPTP)beta/zeta is expressed in different subtypes of human breast cancer
Perez-Pinera P, Garcia-Suarez O, Menendez-Rodriguez P, Mortimer J, Chang Y, Astudillo A, Deuel TF.
Biochem Biophys Res Commun. 2007 Oct 12;362(1):5-10.
Increasing evidence suggests mutations in human breast cancer cells that induce inappropriate expression of the 18-kDa cytokine pleiotrophin (PTN, Ptn) initiate progression of breast cancers to a more malignant phenotype. Pleiotrophin signals through inactivating its receptor, the receptor protein tyrosine phosphatase (RPTP)beta/zeta, leading to increased tyrosine phosphorylation of different substrate proteins of RPTPbeta/zeta, including beta-catenin, beta-adducin, Fyn, GIT1/Cat-1, and P190RhoGAP. PTN signaling thus has wide impact on different important cellular systems. Recently, PTN was found to activate anaplastic lymphoma kinase (ALK) through the PTN/RPTPbeta/zeta signaling pathway; this discovery potentially is very important, since constitutive ALK activity of nucleophosmin (NPM)-ALK fusion protein is causative of anaplastic large cell lymphomas, and, activated ALK is found in other malignant cancers. Recently ALK was identified in each of 63 human breast cancers from 22 subjects. We now demonstrate that RPTPbeta/zeta is expressed in each of these same 63 human breast cancers that previously were found to express ALK and in 10 additional samples of human breast cancer. RPTPbeta/zeta furthermore was localized not only in its normal association with the cell membrane but also scattered in cytoplasm and in nuclei in different breast cancer cells and, in the case of infiltrating ductal carcinomas, the distribution of RPTPbeta/zeta changes as the breast cancer become more malignant. The data suggest that the PTN/RPTPbeta/zeta signaling pathway may be constitutively activated and potentially function to constitutively activate ALK in human breast cancer.
Anaplastic lymphoma kinase is activated through the pleiotrophin/receptor protein-tyrosine phosphatase beta/zeta signaling pathway: an alternative mechanism of receptor tyrosine kinase activation
Perez-Pinera P, Zhang W, Chang Y, Vega JA, Deuel TF.
J Biol Chem. 2007 Sep 28;282(39):28683-90.
Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase (RTK) first discovered as the constitutively active nucleophosmin-ALK oncoprotein in anaplastic large cell lymphomas (ALCL). Full-length ALK has a critical role in normal development and differentiation. Activated full-length ALK also is found in different malignant cancers. Nevertheless, the ligand to activate ALK remained unknown until recently, when ALK was proposed to be the physiological receptor of the cytokine pleiotrophin (PTN, Ptn). However, earlier studies had demonstrated that receptor protein tyrosine phosphatase (RPTP) beta/zeta is a physiological PTN receptor. We now demonstrate that phosphorylation of ALK in PTN-stimulated cells is mediated through the PTN/RPTPbeta/zeta signaling pathway. ALK is phosphorylated independently of a direct interaction of PTN with ALK. The data thus support a unique model of ALK activation. In cells not stimulated by PTN, RPTPbeta/zeta dephosphorylates ALK at the site(s) in ALK that is undergoing autophosphorylation through autoactivation. In contrast, when RPTPbeta/zeta is inactivated in PTN-stimulated cells, the sites that are autophosphorylated in ALK no longer can be dephosphorylated by RPTPbeta/zeta; thus, autoactivation and tyrosine phosphorylation of ALK rapidly increase. The data indicate that the PTN/RPTPbeta/zeta signaling pathway is a critical regulator of the steady state levels of tyrosine phosphorylation and activation of ALK; the data support the conclusion that ALK phosphorylation and activation in PTN-stimulated cells are increased through a unique "alternative mechanism of RTK activation."
Secretion of pleiotrophin stimulates breast cancer progression through remodeling of the tumor microenvironment
Chang Y, Zuka M, Perez-Pinera P, Astudillo A, Mortimer J, Berenson JR, Deuel TF.
Proc Natl Acad Sci U S A. 2007 Jun 26;104(26):10888-93.
Pleiotrophin (PTN, Ptn) is an 18-kDa secretory cytokine expressed in many breast cancers; however, the significance of Ptn expression in breast cancer has not been established. We have now tested three models to determine the role of inappropriate expression of Ptn in breast cancer. Mouse mammary tumor virus (MMTV) promoter-driven Ptn expressed in MMTV-polyoma virus middle T antigen (PyMT)-Ptn mouse breast cancers was first shown to induce rapid growth of morphologically identified foci of "scirrhous" carcinoma and to extensively remodel the microenvironment, including increased tumor angiogenesis and striking increases in mouse protocollagens Ialpha2, IValpha5, and XIalpha1, and elastin. Ectopic Ptn expression in MCF-7 (human breast cancer)-Ptn cell xenografts also was shown to markedly increase MCF-7-Ptn cell xenograft growth in nude mice; furthermore, it induced extensive remodeling of the microenvironment and tumor angiogenesis. In a coculture model of equal numbers of NIH 3T3 stromal fibroblasts and MCF-7-Ptn cells, PTN secreted from MCF-7-Ptn cells was then shown to induce a more malignant MCF-7-Ptn breast cancer cell phenotype and extensive remodeling of the MCF-7-Ptn/NIH 3T3 cell microenvironment; it up-regulated expression of markers of aggressive breast cancers, including PKCdelta and matrix metalloproteinase-9 in both MCF-7-Ptn and NIH 3T3 cells. The morphological phenotypes of MCF-7-Ptn cell xenografts and MCF-7-Ptn cell/NIH 3T3 cell cocultures closely resembled breast cancers in MMTV-PyMT-Ptn mice. Inappropriate expression of Ptn thus promotes breast cancer progression in mice; the data suggest that secretion of PTN through stimulation of the stromal cell microenvironment alone may be sufficient to account for significant features of breast cancer progression.
Anaplastic lymphoma kinase is expressed in different subtypes of human breast cancer
Perez-Pinera P, Chang Y, Astudillo A, Mortimer J, Deuel TF.
Biochem Biophys Res Commun. 2007 Jun 29;358(2):399-403.
Pleiotrophin (PTN, Ptn) is an 18kDa cytokine expressed in human breast cancers. Since inappropriate expression of Ptn stimulates progression of breast cancer in transgenic mice and a dominant negative PTN reverses the transformed phenotype of human breast cancer cells that inappropriately express Ptn, it is suggested that constitutive PTN signaling in breast cancer cells that inappropriately express Ptn activates pathways that promote a more aggressive breast cancer phenotype. Pleiotrophin signals by inactivating its receptor, the receptor protein tyrosine phosphatase (RPTP)beta/zeta, and, recently, PTN was found to activate anaplastic lymphoma kinase (ALK) through the PTN/RPTPbeta/zeta signaling pathway in PTN-stimulated cells, not through a direct interaction of PTN with ALK and thus not through the PTN-enforced dimerization of ALK. Since full-length ALK is activated in different malignant cancers and activated ALK is a potent oncogenic protein, we examined human breast cancers to test the possibility that ALK may be expressed in breast cancers and potentially activated through the PTN/RPTPbeta/zeta signaling pathway; we now demonstrate that ALK is strongly expressed in different histological subtypes of human breast cancer; furthermore, ALK is expressed in both nuclei and cytoplasm and, in the ;;dotted" pattern characteristic of ALK fusion proteins in anaplastic large cell lymphoma. This study thus supports the possibility that activated ALK may be important in human breast cancers and potentially activated either through the PTN/RPTPbeta/zeta signaling pathway, or, alternatively, as an activated fusion protein to stimulate progression of breast cancer in humans.
The Trk tyrosine kinase inhibitor K252a regulates growth of lung adenocarcinomas
Perez-Pinera P, Hernandez T, García-Suárez O, de Carlos F, Germana A, Del Valle M, Astudillo A, Vega JA.
Mol Cell Biochem. 2007 Jan;295(1-2):19-26.
The neurotrophin family of growth factors and their receptors support the survival of several neuronal and non-neuronal cell populations during embryonic development and adult life. Neurotrophins are also involved in malignant transformation. To seek the role of neurotrophin signaling in human lung cancer we studied the expression of neurotrophin receptors in human lung adenocarcinomas and investigated the effect of the neurotrophin receptor inhibitor K252a in A549 cell survival and colony formation ability in soft agar. We showed that human lung adenocarcinomas express TrkA and TrkB, but not TrkC; A549 cells, derived from a human lung adenocarcinoma, express mRNA transcripts encoding nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), TrkA, TrkB, and p75, and high protein levels of TrkA and TrkB. Stimulation of cells using NGF or BDNF activates the anti-apoptotic protein Akt. Interestingly, inhibition of neurotrophin receptor signaling using K252a prevents Akt activation in response to NGF or BDNF, induces apoptotic cell death, and diminishes the ability of A549 cells to growth in soft agar. The data suggest that neurotrophin signaling inhibition using k252a may be a valid therapy to treat patients with lung adenocarcinomas.
Sodium chloride regulates Extracellular Regulated Kinase 1/2 in different tumor cell lines
Perez-Pinera P, Menendez-Gonzalez M, del Valle M, Vega JA.Mol
Cell Biochem. 2006 Dec;293(1-2):93-101.
Perturbations of the extracellular ionic content by different hypo- or hyperosmolar stimuli initiate stress responses to maintain cell viability that include activation of Mitogen Activated Protein Kinases (MAPK) in cell lines derived from kidney epithelium. When hyperosmolar conditions induced by different salts occurred in the extracellular environment of tumor-derived cell lines, they activated the Extracellular Regulated Kinase 1/2 by increasing its phosphorylation steady-state on Thr202/Tyr204 in a time- and dose-dependent manner. It was found that Extracellular Regulated Kinase 1/2 activation is a consequence of selective phosphorylation by mitogen-activated protein kinase/ERK kinase. Changes in cell shape or in tubulin or actin cytoskeletal structure were not found, although cell growth arrest was observed as well as induction of apoptosis and modified cell migration ability that were dependent upon Extracellular Regulated Kinase 1/2 activation evidencing a critical role for the Extracellular Regulated Kinase 1/2 in mediating survival of cells in hyperosmotic conditions.
Pleiotrophin disrupts calcium-dependent homophilic cell-cell adhesion and initiates an epithelial-mesenchymal transition
Perez-Pinera P, Alcantara S, Dimitrov T, Vega JA, Deuel TF.
Proc Natl Acad Sci U S A. 2006 Nov 21;103(47):17795-800.
Regulation of the levels of tyrosine phosphorylation is essential to maintain the functions of proteins in different signaling pathways and other cellular systems, but how the steady-state levels of tyrosine phosphorylation are coordinated in different cellular systems to initiate complex cellular functions remains a formidable challenge. The receptor protein tyrosine phosphatase (RPTP)beta/zeta is a transmembrane tyrosine phosphatase whose substrates include proteins important in intracellular and transmembrane protein-signaling pathways, cytoskeletal structure, cell-cell adhesion, endocytosis, and chromatin remodeling. Pleiotrophin (PTN the protein and Ptn the gene) is a ligand for RPTPbeta/zeta; PTN inactivates RPTPbeta/zeta, leaving unchecked the continued endogenous activity of tyrosine kinases that increase phosphorylation of the substrates of RPTPbeta/zeta at sites dephosphorylated by RPTPbeta/zeta in cells not stimulated by PTN. Thus, through the regulation of the tyrosine phosphatase activity of RPTPbeta/zeta, the PTN/RPTPbeta/zeta signaling pathway coordinately regulates the levels of tyrosine phosphorylation of proteins in many cellular systems. We now demonstrate that PTN disrupts cytoskeletal protein complexes, ablates calcium-dependent homophilic cell-cell adhesion, stimulates ubiquitination and degradation of N-cadherin, reorganizes the actin cytoskeleton, and induces a morphological epithelial-mesenchymal transition (EMT) in PTN-stimulated U373 cells. The data suggest that increased tyrosine phosphorylation of the different substrates of RPTPbeta/zeta in PTN-stimulated cells alone is sufficient to coordinately stimulate the different functions needed for an EMT; it is possible that PTN initiates an EMT in cells at sites where PTN is expressed in development and in malignant cells that inappropriately express Ptn.
Hypertonicity activates GSK3beta in tumor cells
Perez-Pinera P, Menendez-Gonzalez M, del Valle M, Vega JA.
Mol Cell Biochem. 2006 Oct;291(1-2):93-100.
Responses to perturbations in the composition of the extracellular environment are crucial to maintain cell and tissue homeostasis. In hypertonic conditions cell lines derived from kidney epithelium initiate a variety of stress responses to maintain cell viability that include activation of Mitogen Activated Protein Kinases (MAPK). We previously showed that NaCl also regulates MAPK in different tumor cell lines and we now show that when hypertonic conditions induced with NaCl and other osmolytes were used to stimulate several tumor cell lines, Glycogen Synthase Kinase 3beta (GSK3beta) was rapidly dephosphorylated at serine 9 and its kinase activity was increased. This response was both time- and dose-dependent, it was independent of the Akt signaling pathway and did not increase steady state levels of phosphorylation of beta-catenin, although the data suggested that activated GSK3beta could regulate the activity of ERK1/2.
Identification of the angiogenesis signaling domain in pleiotrophin defines a mechanism of the angiogenic switch
Zhang N, Zhong R, Perez-Pinera P, Herradon G, Ezquerra L, Wang ZY, Deuel TF.
Biochem Biophys Res Commun. 2006 May 5;343(2):653-8.
Neoplasms progress through genetic and epigenetic mutations that deregulate pathways in the malignant cell that stimulate more aggressive growth of the malignant cell itself and/or remodel the tumor microenvironment to support the developing tumor mass. The appearance of new blood vessels in malignant tumors is known as the "angiogenic switch." The angiogenic switch triggers a stage of rapid tumor growth supported by extensive tumor angiogenesis and a more aggressive tumor phenotype and its onset is a poor prognostic indicator for host survival. Identification of the factors that stimulate the angiogenic switch thus is of high importance. Pleiotrophin (PTN the protein, Ptn the gene) is an angiogenic factor and the Ptn gene has been found to be constitutively expressed in many human tumors of different cell types. These studies use a nude mouse model to test if Ptn constitutively expressed in premalignant cells is sufficient to trigger an angiogenic switch in vivo. We introduced an ectopic Ptn gene into "premalignant" SW-13 cells and analyzed the phenotype of SW-13 Ptn cell tumor implants in the flanks of nude mice. SW-13 Ptn cell subcutaneous tumor implants grew very rapidly and had a striking increase in the density of new blood vessels compared to the SW-13 cell tumor implants, suggesting that constitutive PTN signaling in the premalignant SW-13 cell implants in the nude mouse recapitulates fully the angiogenic switch. It was found also that ectopic expression of the C-terminal domain of PTN in SW-13 cell implants was equally effective in initiating an angiogenic switch as the full-length PTN whereas implants of SW-13 cells in nude mice that express the N-terminal domain of PTN grew rapidly but failed to develop tumor angiogenesis. The data suggest the possibility that mutations that activate Ptn in premalignant cells are sufficient to stimulate an angiogenic switch in vivo and, since these mutations are frequently found in human malignancies, that constitutive PTN signaling may be an important contributor to progression of human tumors. The data also suggest that the C-terminal and the N-terminal domains of PTN equally initiate switches in premalignant cells to cells of a more aggressive tumor phenotype but the separate domains of PTN signal different mechanisms and perhaps signal through activation of a separate receptor-like protein.
Thymocyte depletion affects neurotrophin receptor expression in thymic stromal cells
Pérez-Piñera P, García-Suarez O, Prieto JG, Germana A, Ciriaco E, del Valle ME, Vega JA.
J Anat. 2006 Feb;208(2):231-8.
Thymocytes and thymic stromal cells cross-talk in a bidirectional manner within the thymus, thus contributing to the generation of mature T-cells. The thymic stromal cells in the rat express the high- (TrkA, TrkB) and low-affinity (p75NTR) receptors for neurotrophins. In this study we analysed the regulation of TrkA, TrkB and p75NTR expression in the rat thymus by thymocytes. We induced thymocyte apoptosis by administration of corticoids in rats, and then analysed the expression and distribution of these receptors 1, 4 and 10 days later. Thymocyte death was assessed by the activation of caspase-3 in cells undergoing apoptosis. We observed massive thymocyte apoptosis 1 day after injection and, to a lesser extent, after 4 days, which was parallel with a reduction in the density of thymic epithelial cells normally expressing TrkA and p75NTR. Furthermore, TrkA expression was found in cortical thymic epithelial cells, which normally lack this receptor. The expression of TrkB was restricted to a subset of macrophage-dendritic cells, and remained unchanged with treatment. The normal pattern of neurotrophin receptor expression was almost completely restored by day 10. The results demonstrate that the expression of neurotrophin receptors by thymic epithelial cells, but not by macrophage-dendritic cells, is regulated by thymocytes.
Pleiotrophin regulates serine phosphorylation and the cellular distribution of beta-adducin through activation of protein kinase C
Pariser H, Herradon G, Ezquerra L, Perez-Pinera P, Deuel TF.
Proc Natl Acad Sci U S A. 2005 Aug 30;102(35):12407-12.
Pleiotrophin (PTN) was found to regulate tyrosine phosphorylation of beta-adducin through the PTN/receptor protein tyrosine phosphatase (RPTP)beta/zeta signaling pathway. We now demonstrate that PTN stimulates the phosphorylation of serines 713 and 726 in the myristoylated alanine-rich protein kinase (PK) C substrate domain of beta-adducin through activation of either PKC alpha or beta. We also demonstrate that PTN stimulates translocation of phosphoserine 713 and 726 beta-adducin either to nuclei, where it associates with nuclear chromatin and with centrioles of dividing cells, or to a membrane-associated site, depending on the phase of cell growth. Furthermore, we demonstrate that PTN stimulates the degradation of beta-adducin in PTN-stimulated cells. Phosphorylation of serines 713 and 726 in beta-adducin is known to markedly reduce the affinity of beta-adducin for spectrin and actin and to uncouple actin/spectrin/beta-adducin multimeric complexes needed for cytoskeletal stability. The data thus suggest that the PTN-stimulated phosphorylation of serines 713 and 726 in beta-adducin disrupts cytoskeletal protein complexes and integrity, features demonstrated in both PTN-stimulated cells and of highly malignant cells that constitutively express the endogenous Ptn gene. The data also support the important conclusion that PTN determines the cellular location of beta-adducin phosphorylated in serines 713 and 726 and raise the possibility that beta-adducin functions in support of structure of heterochromatin and centrioles during mitosis.
Pleiotrophin stimulates tyrosine phosphorylation of beta-adducin through inactivation of the transmembrane receptor protein tyrosine phosphatase beta/zeta
Pariser H, Perez-Pinera P, Ezquerra L, Herradon G, Deuel TF.
Biochem Biophys Res Commun. 2005 Sep 16;335(1):232-9.
Pleiotrophin (PTN the protein, Ptn the gene) signals through a unique mechanism; it inactivates the tyrosine phosphatase activity of its receptor, the transmembrane receptor protein tyrosine phosphatase (RPTP)beta/zeta, and increases tyrosine phosphorylation of the substrates of RPTPbeta/zeta through the continued activity of a yet to be described protein tyrosine kinase(s) in PTN-stimulated cells. We have now found that the cytoskeletal protein beta-adducin interacts with the intracellular domain of RPTPbeta/zeta in a yeast two-hybrid system, that beta-adducin is a substrate of RPTPbeta/zeta, that beta-adducin is phosphorylated in tyrosine in cells not stimulated by PTN, and that tyrosine phosphorylation of beta-adducin is sharply increased in PTN-stimulated cells, suggesting that beta-adducin is a downstream target of and regulated by the PTN/RPTPbeta/zeta signaling pathway. beta-Catenin was the first downstream target of the PTN/RPTPbeta/zeta signaling pathway to be identified; these data thus also suggest that PTN coordinately regulates steady state levels of tyrosine phosphorylation of the important cytoskeletal proteins beta-adducin and beta-catenin and, through PTN-stimulated tyrosine phosphorylation, beta-adducin may contribute to the disruption of cytoskeletal structure, increased plasticity, and loss of homophilic cell-cell adhesion that are the consequences of PTN stimulation of cells and a characteristic feature of different malignant cells with mutations that activate constitutive expression of the endogenous Ptn gene.
Fyn is a downstream target of the pleiotrophin/receptor protein tyrosine phosphatase beta/zeta-signaling pathway: regulation of tyrosine phosphorylation of Fyn by pleiotrophin
Pariser H, Ezquerra L, Herradon G, Perez-Pinera P, Deuel TF.
Biochem Biophys Res Commun. 2005 Jul 8;332(3):664-9.
Pleiotrophin (PTN the protein, Ptn the gene) signals downstream targets through inactivation of its receptor, the transmembrane receptor protein tyrosine phosphatase (RPTP)beta/zeta, disrupting the balanced activity of RPTPbeta/zeta and the activity of a constitutively active tyrosine kinase. As a consequence of the inactivation of RPTPbeta/zeta, PTN stimulates a sharp increase in the levels of tyrosine phosphorylation of the substrates of RPTPbeta/zeta in PTN-stimulated cells. We now report that the Src family member Fyn interacts with the intracellular domain of RPTPbeta/zeta in a yeast two-hybrid system. We further demonstrate that Fyn is a substrate of RPTPbeta/zeta, and that tyrosine phosphorylation of Fyn is sharply increased in PTN-stimulated cells. In previous studies, we demonstrated that beta-catenin and beta-adducin are targets of the PTN/RPTPbeta/zeta-signaling pathway and defined the mechanisms through which tyrosine phosphorylation of beta-catenin and beta-adducin disrupts cytoskeletal protein complexes. We conclude that Fyn is a downstream target of the PTN/RPTPbeta/zeta-signaling pathway and suggest that PTN coordinately regulates tyrosine phosphorylation of beta-catenin, beta-adducin, and Fyn through the PTN/RPTPbeta/zeta-signaling pathway and that together Fyn, beta-adducin, and beta-catenin may be effectors of the previously described PTN-stimulated disruption of cytoskeletal stability, increased cell plasticity, and loss of cell-cell adhesion that are characteristic of PTN-stimulated cells and a feature of many human malignant cells in which mutations have established constitutive expression of the Ptn gene.
S-100 proteins in the human peripheral nervous system
Gonzalez-Martinez T, Perez-Piñera P, Díaz-Esnal B, Vega JA.
Microsc Res Tech. 2003 Apr 15;60(6):633-8.
This article reviews the distribution of S100 proteins in the human peripheral nervous system. The expression of S100 by peripheral glial cells seems to be a distinctive fact of these cells, independently of their localization and their ability to myelinate or not. S100 proteins expressing cells include satellite cells of sensory, sympathetic and enteric ganglia, supporting cells of the adrenal medulla, myelinating and non-myelinating Schwann cells in the nerve trunks, and the Schwann-related cells of sensory corpuscles. In addition, S100 proteins are expressed in peripheral neurons. Most of them express S100alpha protein, and a subpopulation of sensory neurons in dorsal root ganglia contains S100beta protein or S100alpha plus S100beta proteins.
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