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Sami A, Selzer ME, Li S. Advances in the Signaling Pathways Downstream of Glial-Scar Axon Growth Inhibitors. Front Cell Neurosci 2020; 14:174. [PMID: 32714150 PMCID: PMC7346763 DOI: 10.3389/fncel.2020.00174] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Accepted: 05/22/2020] [Indexed: 12/15/2022] Open
Abstract
Axon growth inhibitors generated by reactive glial scars play an important role in failure of axon regeneration after CNS injury in mature mammals. Among the inhibitory factors, chondroitin sulfate proteoglycans (CSPGs) are potent suppressors of axon regeneration and are important molecular targets for designing effective therapies for traumatic brain injury or spinal cord injury (SCI). CSPGs bind with high affinity to several transmembrane receptors, including two members of the leukocyte common antigen related (LAR) subfamily of receptor protein tyrosine phosphatases (RPTPs). Recent studies demonstrate that multiple intracellular signaling pathways downstream of these two RPTPs mediate the growth-inhibitory actions of CSPGs. A better understanding of these signaling pathways may facilitate development of new and effective therapies for CNS disorders characterized by axonal disconnections. This review will focus on recent advances in the downstream signaling pathways of scar-mediated inhibition and their potential as the molecular targets for CNS repair.
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Affiliation(s)
- Armin Sami
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States.,Department of Anatomy and Cell Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
| | - Michael E Selzer
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States.,Department of Neurology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
| | - Shuxin Li
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States.,Department of Anatomy and Cell Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
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2
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Ohtake Y, Saito A, Li S. Diverse functions of protein tyrosine phosphatase σ in the nervous and immune systems. Exp Neurol 2018; 302:196-204. [PMID: 29374568 PMCID: PMC6275553 DOI: 10.1016/j.expneurol.2018.01.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 01/10/2018] [Accepted: 01/17/2018] [Indexed: 02/07/2023]
Abstract
Tyrosine phosphorylation is a common means of regulating protein functions and signal transduction in multiple cells. Protein tyrosine phosphatases (PTPs) are a large family of signaling enzymes that remove phosphate groups from tyrosine residues of target proteins and change their functions. Among them, receptor-type PTPs (RPTPs) exhibit a distinct spatial pattern of expression and play essential roles in regulating neurite outgrowth, axon guidance, and synaptic organization in developmental nervous system. Some RPTPs function as essential receptors for chondroitin sulfate proteoglycans that inhibit axon regeneration following CNS injury. Interestingly, certain RPTPs are also important to regulate functions of immune cells and development of autoimmune diseases. PTPσ, a RPTP in the LAR subfamily, is expressed in various immune cells and regulates their differentiation, production of various cytokines and immune responses. In this review, we highlight the physiological and pathological significance of PTPσ and related molecules in both nervous and immune systems.
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Affiliation(s)
- Yosuke Ohtake
- Department of Biochemistry, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8553, Japan
| | - Atsushi Saito
- Department of Stress Protein Processing, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8553, Japan
| | - Shuxin Li
- Shriners Hospitals Pediatric Research Center, Department of Anatomy and Cell Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA.
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3
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Yu P, Pearson CS, Geller HM. Flexible Roles for Proteoglycan Sulfation and Receptor Signaling. Trends Neurosci 2018; 41:47-61. [PMID: 29150096 PMCID: PMC5748001 DOI: 10.1016/j.tins.2017.10.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 10/19/2017] [Accepted: 10/25/2017] [Indexed: 11/25/2022]
Abstract
Proteoglycans (PGs) in the extracellular matrix (ECM) play vital roles in axon growth and navigation, plasticity, and regeneration of injured neurons. Different classes of PGs may support or inhibit cell growth, and their functions are determined in part by highly specific structural features. Among these, the pattern of sulfation on the PG sugar chains is a paramount determinant of a diverse and flexible set of outcomes. Recent studies of PG sulfation illustrate the challenges of attributing biological actions to specific sulfation patterns, and suggest ways in which highly similar molecules may exert opposing effects on neurons. The receptors for PGs, which have yet to be fully characterized, display a similarly nuanced spectrum of effects. Different classes of PG function via overlapping families of receptors and signaling pathways. This enables them to control axon growth and guidance with remarkable specificity, but it poses challenges for determining the precise binding interactions and downstream effects of different PGs and their assorted sulfated epitopes. This review examines existing and emerging evidence for the roles of PG sulfation and receptor interactions in determining how these complex molecules influence neuronal development, growth, and function.
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Affiliation(s)
- Panpan Yu
- Guangdong-Hongkong-Macau Institute of CNS Regeneration; Ministry of Education Joint International Research Laboratory of CNS Regeneration, Jinan University, Guangzhou 510632, China.
| | - Craig S Pearson
- Laboratory of Developmental Neurobiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA; Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Herbert M Geller
- Laboratory of Developmental Neurobiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
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4
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Cui J, Zheng H, Zhang J, Jia L, Feng Y, Wang W, Li H, Chen F. Profiling of glycan alterations in regrowing limb tissues of Cynops orientalis. Wound Repair Regen 2017; 25:836-845. [PMID: 28857387 DOI: 10.1111/wrr.12580] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 07/31/2017] [Indexed: 02/02/2023]
Abstract
Glycans are known to play important roles in molecular recognition, cell-cell adhesion, molecular trafficking, receptor activation, and signal transduction during development and regeneration. Despite numerous investigations of regenerating salamander limbs, global analysis of the precise variation of glycans during the limb regeneration process has received little attention. Here, we have used lectin microarrays and lectin histochemistry to analyze the alterations and distribution of glycans during the early stages leading to blastema formation during Cynops orientalis limb regeneration in response to limb amputation. Compared with the control group, analysis at several time points (3, 7, and 14 days postamputation) using microarrays containing 37 lectins showed that limb tissues expressed significantly different complements of glycans recognized by 9 different lectins. Postamputation limb tissues showed higher expression of two glycan structures recognized by the lectins STL and LTL and lower expression of seven glycan structures recognized by PHA-E, MAL-I, SNA, UEA-I, PHA-E + L, VVA, and GNA. We also observed significant changes in glycans specifically at 7 days postamputation, including higher binding capacity by WFA, GSL-I, and NPA and lower binding capacity by PNA, HHL, ConA, LCA, GSL-II, and PWM. Next, we validated our lectin microarray data using lectin histochemistry in limb tissues. Glycans recognized by STL and GNA showed similar changes in signal intensity to those found in the lectin microarrays, with STL staining in the cytoplasm and GNA in the cytoplasm and nucleus. Our findings are the first report of significant postamputation changes in glycans in limb tissues and suggest that those glycans perform potentially important functions during the early stages of C. orientalis limb regeneration.
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Affiliation(s)
- Jihong Cui
- Lab of Tissue Engineering, College of Life Sciences, Northwest University, Xi'an 710069, People's Republic of China.,Provincial Key Laboratory of Biotechnology of Shaanxi, Xi'an 710069, People's Republic of China.,Key Laboratory of Resource Biology and Biotechnology in Western China Ministry of Education, Xi'an, People's Republic of China
| | - Hanxue Zheng
- Lab of Tissue Engineering, College of Life Sciences, Northwest University, Xi'an 710069, People's Republic of China
| | - Jing Zhang
- Lab of Tissue Engineering, College of Life Sciences, Northwest University, Xi'an 710069, People's Republic of China
| | - Liyuan Jia
- Lab of Tissue Engineering, College of Life Sciences, Northwest University, Xi'an 710069, People's Republic of China
| | - Yalong Feng
- Lab of Tissue Engineering, College of Life Sciences, Northwest University, Xi'an 710069, People's Republic of China
| | - Wenjun Wang
- Lab of Tissue Engineering, College of Life Sciences, Northwest University, Xi'an 710069, People's Republic of China
| | - Hongmin Li
- Lab of Tissue Engineering, College of Life Sciences, Northwest University, Xi'an 710069, People's Republic of China.,Provincial Key Laboratory of Biotechnology of Shaanxi, Xi'an 710069, People's Republic of China.,Key Laboratory of Resource Biology and Biotechnology in Western China Ministry of Education, Xi'an, People's Republic of China
| | - Fulin Chen
- Lab of Tissue Engineering, College of Life Sciences, Northwest University, Xi'an 710069, People's Republic of China.,Provincial Key Laboratory of Biotechnology of Shaanxi, Xi'an 710069, People's Republic of China.,Key Laboratory of Resource Biology and Biotechnology in Western China Ministry of Education, Xi'an, People's Republic of China
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5
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Abstract
The protein kinase C (PKC) family of proteins mediates the action of growth factors and other ligands by activating a network of transcription factors that bind to TRE sequences in the promoters of many genes that regulate cell proliferation, differentiation, extracellular matrix synthesis, apoptosis and others in a cell type-, isozymeand context-specific manner. The critical role of PKC in embryonic development is indicated by early death of embryos in which one or more of these isozymes are inactivated. Our studies together with others show that palatal PKC signalling is functional and may be essential for normal palate development. Although single gene knockouts have failed to exhibit the cleft palate (CP) phenotype, owing to compensation by other kinases, many chemicals including the mycotoxin, secalonic acid D, disrupt palatal PKC signalling leading to altered palatal mesenchymal gene expression. The potential relevance of such effects to chemical-induced CP is discussed.
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Affiliation(s)
- Chada S Reddy
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA.
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6
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Ohtake Y, Li S. Molecular mechanisms of scar-sourced axon growth inhibitors. Brain Res 2014; 1619:22-35. [PMID: 25192646 DOI: 10.1016/j.brainres.2014.08.064] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 08/21/2014] [Indexed: 12/29/2022]
Abstract
Astrogliosis is a defense response of the CNS to minimize primary damage and to repair injured tissues, but it ultimately generates harmful effects by upregulating inhibitory molecules to suppress neuronal elongation and forming potent barriers to axon regeneration. Chondroitin sulfate proteoglycans (CSPGs) are highly expressed by reactive scars and are potent contributors to the non-permissive environment in mature CNS. Surmounting strong inhibition by CSPG-rich scar is an important therapeutic goal for achieving functional recovery after CNS injuries. Currently, enzymatic digestion of CSPGs with locally applied chondroitinase ABC is the main in vivo approach to overcome scar inhibition, but several disadvantages may prevent using this bacterial enzyme as a therapeutic option for patients. A better understanding of molecular mechanisms underlying CSPG function may facilitate development of new effective therapies to overcome scar-mediated inhibition. Previous studies support that CSPGs act by non-specifically hindering the binding of matrix molecules to their cell surface receptors through steric interactions, but two members of the leukocyte common antigen related (LAR) phosphatase subfamily, protein tyrosine phosphatase σ and LAR, are functional receptors that bind CSPGs with high affinity and mediate CSPG inhibition. CSPGs may also act by binding two receptors for myelin-associated growth inhibitors, Nogo receptors 1 and 3. Thus, CSPGs inhibit axon growth through multiple mechanisms, making them especially potent and difficult therapeutic targets. Identification of CSPG receptors is not only important for understanding the scar-mediated growth suppression, but also for developing novel and selective therapies to promote axon sprouting and/or regeneration after CNS injuries. This article is part of a Special Issue entitled SI: Spinal cord injury.
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Affiliation(s)
- Yosuke Ohtake
- Shriners Hospitals Pediatric Research Center and Department of Anatomy and Cell Biology, Temple University School of Medicine, 3500N. Broad Street, Philadelphia 19140, PA, USA
| | - Shuxin Li
- Shriners Hospitals Pediatric Research Center and Department of Anatomy and Cell Biology, Temple University School of Medicine, 3500N. Broad Street, Philadelphia 19140, PA, USA.
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7
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Scar-modulating treatments for central nervous system injury. Neurosci Bull 2014; 30:967-984. [PMID: 24957881 DOI: 10.1007/s12264-013-1456-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 04/09/2014] [Indexed: 02/04/2023] Open
Abstract
Traumatic injury to the adult mammalian central nervous system (CNS) leads to complex cellular responses. Among them, the scar tissue formed is generally recognized as a major obstacle to CNS repair, both by the production of inhibitory molecules and by the physical impedance of axon regrowth. Therefore, scar-modulating treatments have become a leading therapeutic intervention for CNS injury. To date, a variety of biological and pharmaceutical treatments, targeting scar modulation, have been tested in animal models of CNS injury, and a few are likely to enter clinical trials. In this review, we summarize current knowledge of the scar-modulating treatments according to their specific aims: (1) inhibition of glial and fibrotic scar formation, and (2) blockade of the production of scar-associated inhibitory molecules. The removal of existing scar tissue is also discussed as a treatment of choice. It is believed that only a combinatorial strategy is likely to help eliminate the detrimental effects of scar tissue on CNS repair.
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8
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Wang L, Lam JSY, Zhao H, Wang J, Chan SO. Localization of protein kinase C isoforms in the optic pathway of mouse embryos and their role in axon routing at the optic chiasm. Brain Res 2014; 1575:22-32. [PMID: 24863469 DOI: 10.1016/j.brainres.2014.05.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 05/08/2014] [Accepted: 05/16/2014] [Indexed: 12/16/2022]
Abstract
Protein kinase C (PKC) plays a key role in many receptor-mediated signaling pathways that regulate cell growth and development. However, its roles in guiding axon growth and guidance in developing neural pathways are largely unknown. To investigate possible functions of PKC in the growth and guidance of axons in the optic chiasm, we first determined the localization of major PKC isoforms in the retinofugal pathway of mouse embryos, at the stage when axons navigate through the midline. Results showed that PKC was expressed in isoform specific patterns in the pathway. PKC-α immunoreactivity was detected in the chiasm and the optic tract. PKC-βΙΙ was strong in the optic stalk but was attenuated on axons in the diencephalon. Immunostaining for PKC-ε showed a colocalization in the chiasmatic neurons that express a surface antigen stage specific embryonic antigen-1 (SSEA-1). These chiasmatic neurons straddled the midline of the optic chiasm, and have been shown in earlier studies a role in regulation of axon growth and guidance. Expression levels of PKC-βΙ, -δ and -γ were barely detectable in the pathway. Blocking of PKC signaling with Ro-32-0432, an inhibitor specific for PKC-α and -β at nanomolar concentration, produced a dramatic reduction of ipsilateral axons from both nasal retina and temporal crescent. We conclude from these studies that PKC-α and -βΙΙ are the predominant forms in the developing optic pathway, whereas PKC-ε is the major form in the chiasmatic neurons. Furthermore, PKC-α and -βΙΙ are likely involved in signaling pathways triggered by inhibitory molecules at the midline that guide optic axons to the uncrossed pathway.
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Affiliation(s)
- Liqing Wang
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China; Department of Neurology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong, China.
| | - Joyce Shi-Ying Lam
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
| | - Hui Zhao
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
| | - Jun Wang
- Department of Anatomy and Embryology, School of Basic Medical Sciences, Peking University, Beijing, China.
| | - Sun-On Chan
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
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9
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Abstract
Glycans participate in many key cellular processes during development and in physiology and disease. In this review, the functional role of various glycans in the regeneration of neurons and body parts in adult metazoans is discussed. Understanding glycosylation may facilitate research in the field of stem cell biology and regenerative medicine.
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Affiliation(s)
- Ponnusamy Babu
- Glycomics and Glycoproteomics,
Centre for Cellular and Molecular Platforms, NCBS-TIFR, GKVK Post, Bangalore 560065, India
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10
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Abstract
Axon regeneration is crucial for recovery of function after nervous system injury. Over many years, research has uncovered numerous factors which prevent damaged axons from regrowing and reforming functional connections after damage. These factors are both extrinsic, relating to the central nervous system environment, and intrinsic, relating to the growth capacity of the neurons themselves. In this short review, I summarize these elements with a view to illustrating how they may be overcome to promote nervous system repair.
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Affiliation(s)
- Andrew J Murray
- Department of Biochemistry and Molecular Biophysics, Columbia University, 701 W 168th Street, New York, NY, 10032, USA,
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11
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Peng J, Pan Q, Zhang W, Yang H, Zhou X, Jiang H. Effects of DS-modified agarose gels on neurite extension in 3D scaffold through mechanisms other than changing the pore radius of the gels. J Biomed Mater Res A 2013; 102:2157-62. [PMID: 23894002 DOI: 10.1002/jbm.a.34892] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 06/26/2013] [Accepted: 07/22/2013] [Indexed: 01/30/2023]
Abstract
Dermatan sulfate is widely distributed as glycosaminoglycan side chains of proteoglycans, which are the main components of glial scar and inhibit neurite regeneration after nerve injury. However its role in the inhibiting process is not clear. Understanding neurite extension in three-dimensional scaffolds is critical for neural tissue engineering. This study used agarose gels modified with dermatan sulfate as the three-dimensional culture scaffold. We explored structure-function relationship between the three-dimensional scaffold and neurite extension and examined the role of dermatan sulfate on neurite extension in the three-dimensional scaffold. A range of agarose concentrations was used to generate varied gel physical structures and the corresponding neurite extension of embryonic day (E9) chick dorsal root ganglia was examined. We measured gel stiffness and gel pore size to determine whether dermatan sulfate changed the gels' conformation. As gel concentration increased, neurite length and gel pore size decreased, and gel stiffness increased. At 1.00 and 1.25% (wt/vol) concentrations, dermatan sulfates both immobilized with agarose gels and dissolved in culture medium inhibit neurite extension. While at 1.50 and 1.75% (wt/vol) concentrations, only immobilized dermatan sulfate worked. Immobilized dermatan sulfate could modify molecular shape of agarose gels, decrease gel pore size statistically, but did not influence gel stiffness. We have proved that the decrease of gel pore size is insufficient to inhibit neurite extension. These results indicate that dermatan sulfate inhibits neurite extension not through forming a mechanical barrier. Maybe its interaction with neuron membrane is the key factor in neurite extension.
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Affiliation(s)
- Jin Peng
- West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan Province, People's Republic of China; Metabonomics and Multidisciplinary Laboratory for Trauma Research, Sichuan Provincial People's Hospital, Sichuan Academy of Medical Sciences, Chengdu, Sichuan Province, People's Republic of China
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12
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Sharma K, Selzer ME, Li S. Scar-mediated inhibition and CSPG receptors in the CNS. Exp Neurol 2012; 237:370-8. [PMID: 22836147 PMCID: PMC5454774 DOI: 10.1016/j.expneurol.2012.07.009] [Citation(s) in RCA: 136] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 07/14/2012] [Indexed: 11/21/2022]
Abstract
Severed axons in adult mammals do not regenerate appreciably after central nervous system (CNS) injury due to developmentally determined reductions in neuron-intrinsic growth capacity and extracellular environment for axon elongation. Chondroitin sulfate proteoglycans (CSPGs), which are generated by reactive scar tissues, are particularly potent contributors to the growth-limiting environment in mature CNS. Thus, surmounting the strong inhibition by CSPG-rich scar is an important therapeutic goal for achieving functional recovery after CNS injuries. As of now, the main in vivo approach to overcoming inhibition by CSPGs is enzymatic digestion with locally applied chondroitinase ABC (ChABC), but several disadvantages may prevent using this bacterial enzyme as a therapeutic option for patients. A better understanding of the molecular mechanisms underlying CSPG action is needed in order to develop more effective therapies to overcome CSPG-mediated inhibition of axon regeneration and/or sprouting. Because of their large size and dense negative charges, CSPGs were thought to act by non-specifically hindering the binding of matrix molecules to their cell surface receptors through steric interactions. Although this may be true, recent studies indicate that two members of the leukocyte common antigen related (LAR) phosphatase subfamily, protein tyrosine phosphatase σ (PTPσ) and LAR, are functional receptors that bind CSPGs with high affinity and mediate CSPG inhibitory effects. CSPGs also may act by binding to two receptors for myelin-associated growth inhibitors, Nogo receptors 1 and 3 (NgR1 and NgR3). If confirmed, it would suggest that CSPGs have multiple mechanisms by which they inhibit axon growth, making them especially potent and difficult therapeutic targets. Identification of CSPG receptors is not only important for understanding the scar-mediated growth suppression, but also for developing novel and selective therapies to promote axon sprouting and/or regeneration after CNS injuries, including spinal cord injury (SCI).
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Affiliation(s)
- Kartavya Sharma
- Department of Neurology and Neuroscience Graduate Program, UT Southwestern Medical Center, Dallas, Texas 75390-8813, USA
| | - Michael E. Selzer
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Shuxin Li
- Department of Neurology and Neuroscience Graduate Program, UT Southwestern Medical Center, Dallas, Texas 75390-8813, USA
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13
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Dickendesher TL, Baldwin KT, Mironova YA, Koriyama Y, Raiker SJ, Askew KL, Wood A, Geoffroy CG, Zheng B, Liepmann CD, Katagiri Y, Benowitz LI, Geller HM, Giger RJ. NgR1 and NgR3 are receptors for chondroitin sulfate proteoglycans. Nat Neurosci 2012; 15:703-12. [PMID: 22406547 PMCID: PMC3337880 DOI: 10.1038/nn.3070] [Citation(s) in RCA: 341] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 02/06/2012] [Indexed: 12/17/2022]
Abstract
In the adult mammalian CNS, chondroitin sulfate proteoglycans (CSPGs) and myelin–associated inhibitors (MAIs) stabilize neuronal structure and restrict compensatory sprouting following injury. The Nogo receptor family members NgR1 and NgR2 bind to MAIs and have been implicated in neuronal inhibition. Here we show that NgR1 and NgR3 bind with high–affinity to the glycosaminoglycan moiety of proteoglycans and participate in CSPG inhibition in cultured neurons. Nogo receptor triple mutants (NgR123−/−), but not single mutants, show enhanced axonal regeneration following retro–orbital optic nerve crush injury. The combined loss of NgR1 and NgR3 (NgR13−/−), but not NgR1 and NgR2 (NgR12−/−), is sufficient to mimic the NgR123−/− regeneration phenotype. Regeneration in NgR13−/− mice is further enhanced by simultaneous ablation of RPTPσ, a known CSPG receptor. Collectively, these results identify NgR1 and NgR3 as novel CSPG receptors, demonstrate functional redundancy among CSPG receptors, and provide unexpected evidence for shared mechanisms of MAI and CSPG inhibition.
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Affiliation(s)
- Travis L Dickendesher
- Neuroscience Program, University of Michigan School of Medicine, Ann Arbor, Michigan, USA
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14
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Kelly TAN, Katagiri Y, Vartanian KB, Kumar P, Chen II, Rosoff WJ, Urbach JS, Geller HM. Localized alteration of microtubule polymerization in response to guidance cues. J Neurosci Res 2011; 88:3024-33. [PMID: 20806407 DOI: 10.1002/jnr.22478] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Inhibition of microtubule dynamic instability prevents growth cone turning in response to guidance cues, yet specific changes in microtubule polymerization as growth cones encounter boundaries have not been investigated. In this study, we examined the rate and direction of microtubule polymerization in response to soluble nerve growth factor (NGF) and immobilized chondroitin sulfate proteoglycans (CSPGs) by expressing enhanced GFP-EB3 in rat pheochromocytoma (PC12) cells. GFP-EB3 comets were monitored in live cells using time-lapse epifluorescent microscopy. With an automated tracking system, the rate of microtubule polymerization was calculated as the frame-to-frame displacement of EB3 comets. Our results demonstrate that the rate of microtubule polymerization is increased following NGF treatment, whereas contact with CSPGs decreases microtubule polymerization rates. This reduction in microtubule polymerization rates was specifically localized to neurites in direct contact with CSPGs and not at noncontacting neurites. Additionally, we found an increase in the percentage of microtubules polymerizing in the retrograde direction in neurites at CSPG boundaries, with a concomitant decrease in the rate of retrograde microtubule polymerization. These results implicate localized changes in microtubule dynamics as an important component of the growth cone response to guidance cues.
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Affiliation(s)
- Terri-Ann N Kelly
- Developmental Neurobiology Section, Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
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15
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A chemical screen identifies novel compounds that overcome glial-mediated inhibition of neuronal regeneration. J Neurosci 2010; 30:4693-706. [PMID: 20357120 DOI: 10.1523/jneurosci.0302-10.2010] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A major barrier to regeneration of CNS axons is the presence of growth-inhibitory proteins associated with myelin and the glial scar. To identify chemical compounds with the ability to overcome the inhibition of regeneration, we screened a novel triazine library, based on the ability of compounds to increase neurite outgrowth from cerebellar neurons on inhibitory myelin substrates. The screen produced four "hit compounds," which act with nanomolar potency on several different neuronal types and on several distinct substrates relevant to glial inhibition. Moreover, the compounds selectively overcome inhibition rather than promote growth in general. The compounds do not affect neuronal cAMP levels, PKC activity, or EGFR (epidermal growth factor receptor) activation. Interestingly, one of the compounds alters microtubule dynamics and increases microtubule density in both fibroblasts and neurons. This same compound promotes regeneration of dorsal column axons after acute lesions and potentiates regeneration of optic nerve axons after nerve crush in vivo. These compounds should provide insight into the mechanisms through which glial-derived inhibitors of regeneration act, and could lead to the development of novel therapies for CNS injury.
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16
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Narita M, Suzuki M, Kuzumaki N, Miyatake M, Suzuki T. Implication of activated astrocytes in the development of drug dependence: differences between methamphetamine and morphine. Ann N Y Acad Sci 2008; 1141:96-104. [PMID: 18991953 DOI: 10.1196/annals.1441.032] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Astrocytes are a subpopulation of glial cells that directly affect neuronal function. This review focuses on the potential functional roles of astrocytes in the development of behavioral sensitization and rewarding effects induced by chronic treatment with drugs of abuse. In vitro treatment of cortical neuron/glia cocultures with either methamphetamine or morphine caused activation of astrocytes via protein kinase C (PKC). Purified cortical astrocytes were markedly activated by methamphetamine, whereas morphine had no such effect. Methamphetamine, but not morphine, caused a long-lasting astrocytic activation in cortical neuron/glia cocultures. Morphine-induced behavioral sensitization, assessed as hyperlocomotion, was reversed by 2 months of withdrawal from intermittent morphine administration, whereas behavioral sensitization to methamphetamine-induced hyperlocomotion was maintained even after 2 months of withdrawal. In vivo treatment with methamphetamine, which was associated with behavioral sensitization, caused PKC-dependent astrocytic activation in the mouse cingulate cortex and nucleus accumbens. Furthermore, the glial modulator propentofylline dramatically diminished the activation of astrocytes and the rewarding effect induced by methamphetamine and morphine. On the other hand, intra-nucleus accumbens and intra-cingulate cortex administration of astrocyte-conditioned medium aggravated the development of rewarding effects induced by methamphetamine and morphine. Furthermore, astrocyte-conditioned medium, but not methamphetamine itself, clearly induced differentiation of neural stem cells into astrocytes. These findings provide direct evidence that astrocytes may, at least in part, contribute to the development of the rewarding effects induced by drugs of abuse in the nucleus accumbens and cingulate cortex.
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Affiliation(s)
- Minoru Narita
- Department of Toxicology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, Tokyo, Japan.
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17
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Lam JSY, Wang L, Lin L, Chan SO. Role of protein kinase C in selective inhibition of mouse retinal neurites during contacts with chondroitin sulfates. Neurosci Lett 2008; 434:150-4. [PMID: 18313852 DOI: 10.1016/j.neulet.2008.01.064] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Revised: 01/12/2008] [Accepted: 01/22/2008] [Indexed: 11/29/2022]
Abstract
Chondroitin sulfate proteoglycans elicit a selective inhibition to neurite growth from ventrotemporal (VT) but not dorsonasal (DN) retina, potentiating the bilateral routing of axons in the mouse optic chiasm. We examined whether this selective response is mediated by a difference in protein kinase C (PKC) expression. Effects of suppressing PKC activity in explant preparations of embryonic day 14 retinae with inhibitor Gö6976 or Ro-32-0432 abolished the chondroitin sulfate inhibition to the VT neurites but had no effect to the DN neurites. Whether these responses rely on a difference in expression of PKC in the growth cones was examined using antibodies against six isozymes of PKC. Among these the alpha, betaI and epsilon isozymes were expressed prominently in the retinal growth cones; whilst the betaII, delta and gamma isozymes were barely detected. Moreover, while the alpha and epsilon isozymes were abundant in the filopodial and lamellipodial processes, the betaI isozyme was restricted largely in the core region of the growth cones. Despite these subtype specific localization, there was no significant difference in expression of any of these PKC isozymes between growth cones from VT and DN retina, indicating that the selective response to chondroitin sulfates is not likely generated by a regulation of PKC expression, but by expression of surface molecules that interact with chondroitin sulfate proteoglycans.
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Affiliation(s)
- Joyce Shi-Ying Lam
- Department of Anatomy, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
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18
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Morgan MR, Humphries MJ, Bass MD. Synergistic control of cell adhesion by integrins and syndecans. Nat Rev Mol Cell Biol 2007; 8:957-69. [PMID: 17971838 PMCID: PMC3329926 DOI: 10.1038/nrm2289] [Citation(s) in RCA: 428] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The ability of cells to adhere to each other and to their surrounding extracellular matrices is essential for a multicellular existence. Adhesion provides physical support for cells, regulates cell positioning and enables microenvironmental sensing. The integrins and the syndecans are two adhesion receptor families that mediate adhesion, but their relative and functional contributions to cell-extracellular matrix interactions remain obscure. Recent advances have highlighted connections between the signalling networks that are controlled by these families of receptors. Here we survey the evidence that synergistic signalling is involved in controlling adhesive function and the regulation of cell behaviour in response to the external environment.
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Affiliation(s)
- Mark R. Morgan
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, United Kingdom
| | - Martin J. Humphries
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, United Kingdom
| | - Mark D. Bass
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, United Kingdom
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19
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Major DL, Brady-Kalnay SM. Rho GTPases regulate PTPmu-mediated nasal neurite outgrowth and temporal repulsion of retinal ganglion cell neurons. Mol Cell Neurosci 2007; 34:453-67. [PMID: 17234431 PMCID: PMC1855295 DOI: 10.1016/j.mcn.2006.11.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Revised: 09/25/2006] [Accepted: 11/30/2006] [Indexed: 01/01/2023] Open
Abstract
Members of the receptor protein tyrosine phosphatase (RPTP) subfamily of cell adhesion molecules (CAMs) mediate neurite outgrowth and growth cone repulsion. PTPmu is a growth permissive substrate for nasal retinal ganglion cell (RGC) neurites and a growth inhibitory substrate for temporal RGCs. In this manuscript, we demonstrate that the distinct PTPmu-dependent phenotypes of nasal outgrowth and temporal repulsion are regulated by Rho GTPases. The role of Rho GTPases in the regulation of nasal outgrowth and temporal repulsion was tested by utilizing dominant negative and constitutively active forms of Rac1, RhoA and Cdc42 in Bonhoeffer stripe assays. Nasal neurite outgrowth on PTPmu was blocked by Cdc42-DN. Temporal repulsion to a PTPmu substrate was substantially reduced by addition of Cdc42-DN. The molecule that regulates the switch between permissive versus repulsive responses to PTPmu is Rac1 for temporal neurons. Inhibition of Rac1 is required for repulsion of temporal neurons. Interestingly, adding Rac1-CA to temporal RGC neurons converted PTPmu-dependent repulsion to a permissive response. In addition, adding exogenous Rac1-DN to nasal neurons induced a phenotype switch from a permissive to repulsive response to PTPmu. Together these data suggest that Cdc42 activity is required for both permissive and repulsive responses to PTPmu. However, the key to PTPmu-dependent repulsion is inhibition of Rac1 activity in temporal RGC neurons.
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Affiliation(s)
| | - Susann M. Brady-Kalnay
- *Corresponding author: Susann M. Brady-Kalnay, Department of Molecular Biology and Microbiology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106-4960, Phone: (216) 368-0330, Fax: (216) 368-3055,
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20
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Amadio M, Battaini F, Pascale A. The different facets of protein kinases C: old and new players in neuronal signal transduction pathways. Pharmacol Res 2006; 54:317-25. [PMID: 16996748 DOI: 10.1016/j.phrs.2006.08.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2006] [Revised: 08/08/2006] [Accepted: 08/08/2006] [Indexed: 12/01/2022]
Abstract
Signal transduction pathways are crucial for cell-to-cell communication. Various molecular cascades allow the translation of distinct stimuli, targeting the cell, into a language that the cell itself is able to understand, thus elaborating specific responses. Within this context, a strategic role is played by protein kinases which catalyze the phosphorylation of specific substrates. The serine/threonine protein kinase C (PKC) enzymes family (at least 10 isoforms) is implicated in the transduction of signals coupled to receptor-mediated hydrolysis of membrane phospholipids. Within this molecular pathway, protein-protein interactions play a critical role in directing the distinct activated PKCs towards selective subcellular compartments, in order to guarantee spatio-temporal and localized cellular responses. A space-specific modulation of biochemical events is particularly important during learning. Among the various mechanisms, the modulation of mRNA decay appears to be an efficient post-transcriptional way of controlling gene expression during learning, allowing changes to take place in selected neuronal regions, in particular at synaptic level. To this regard, recent studies have pointed out that PKC activation is also involved in a novel signalling cascade leading to the stabilization of specific mRNAs. This review will especially focus the attention on the implication of PKC in memory trace formation and how alterations within this molecular cascade may have consequences on physiological and pathological neuronal aging (i.e. Alzheimer's disease).
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Affiliation(s)
- Marialaura Amadio
- Department of Experimental and Applied Pharmacology, University of Pavia, Pavia, Italy
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21
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Jin M, Guan CB, Jiang YA, Chen G, Zhao CT, Cui K, Song YQ, Wu CP, Poo MM, Yuan XB. Ca2+-dependent regulation of rho GTPases triggers turning of nerve growth cones. J Neurosci 2006; 25:2338-47. [PMID: 15745960 PMCID: PMC6726106 DOI: 10.1523/jneurosci.4889-04.2005] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Cytoplasmic Ca2+ elevation and changes in Rho GTPase activity are both known to mediate axon guidance by extracellular factors, but the causal relationship between these two events has been unclear. Here we show that direct elevation of cytoplasmic Ca2+ by extracellular application of a low concentration of ryanodine, which activated Ca2+ release from intracellular stores, upregulated Cdc42/Rac, but downregulated RhoA, in cultured cerebellar granule cells and human embryonic kidney 293T cells. Chemoattractive turning of the growth cone triggered by a gradient of ryanodine was blocked by overexpression of mutant forms of Cdc42 but not of RhoA in Xenopus spinal cord neurons. Furthermore, Ca2+-induced GTPase activity correlated with activation of protein kinase C and required a basal activity of Ca2+/calmodulin-dependent protein kinase II. Thus, Rho GTPases may mediate axon guidance by linking upstream Ca2+ signals triggered by guidance factors to downstream cytoskeletal rearrangements.
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Affiliation(s)
- Ming Jin
- Institute of Neuroscience, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, and Graduate School of the Chinese Academy of Sciences, Shanghai 200031, China
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22
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Miyatake M, Narita M, Shibasaki M, Nakamura A, Suzuki T. Glutamatergic neurotransmission and protein kinase C play a role in neuron-glia communication during the development of methamphetamine-induced psychological dependence. Eur J Neurosci 2005; 22:1476-88. [PMID: 16190901 DOI: 10.1111/j.1460-9568.2005.04325.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Methamphetamine (METH) is a strongly addictive psychostimulant that dramatically affects the central nervous system (CNS). On the other hand, protein kinase C (PKC) plays a major role in cellular regulatory and signalling processes that involve protein phosphorylation. The purpose of this study was to investigate the role of neuronal and astrocytic PKC in changes in the central glutamatergic system induced by METH. We show here that in vitro treatment with METH caused the phosphorylation of both neuronal and astrocytic PKC and the activation of astrocytes in cortical neuron/glia co-cultures. Treatment of cortical neuron/glia co-cultures with either the PKC activator phorbol 12,13-dibutyrate (PDBu) or glutamate also caused the PKC-dependent activation of astrocytes. The PKC inhibitor chelerythrine suppressed the Ca2+ responses to glutamate in both cortical neurons and astrocytes. Moreover, a low concentration of PDBu significantly enhanced the Ca2+ responses to glutamate, but not to dopamine, in both cortical neurons and astrocytes. Notably, treatment with METH also enhanced the Ca2+ responses to glutamate in cortical neurons. The activation of astrocytes induced by METH was also reversed by co-treatment with glutamate receptor antagonists (ifenprodil, DNQX or MPEP) in cortical neuron/glia co-cultures. In the conditioned place preference paradigm, intracerebroventricular administration of glutamate receptor antagonists (ifenprodil, DNQX or MPEP) attenuated the METH-induced rewarding effect. These findings provide evidence that the changes in PKC-dependent neuronal and astrocytic glutamatergic transmission induced by METH may, at least in part, contribute to the development of psychological dependence on METH.
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Affiliation(s)
- Mayumi Miyatake
- Department of Toxicology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawaku, Tokyo 142-8501, Japan
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23
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Narita M, Miyatake M, Shibasaki M, Tsuda M, Koizumi S, Narita M, Yajima Y, Inoue K, Suzuki T. Long-lasting change in brain dynamics induced by methamphetamine: enhancement of protein kinase C-dependent astrocytic response and behavioral sensitization. J Neurochem 2005; 93:1383-92. [PMID: 15935054 DOI: 10.1111/j.1471-4159.2005.03097.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It is well known that long-term exposure to psychostimulants induces neuronal plasticity. Recently, accumulating evidence suggests that astrocytes may actively participate in synaptic plasticity. In this study, we found that in vitro treatment of cortical neuron/glia co-cultures with either methamphetamine (METH) or morphine (MRP) caused the activation of astrocytes via protein kinase C (PKC). Purified astrocytes were markedly activated by METH, whereas MRP had no such effect. METH, but not MRP, caused a long-lasting astrocytic activation in cortical neuron/glia co-cultures. Furthermore, MRP-induced behavioral sensitization to hyper-locomotion was reversed by 2 months of withdrawal following intermitted MRP administration, whereas behavioral sensitization to METH-induced hyper-locomotion was maintained even after 2 months of withdrawal. Consistent with this cell culture study, in vivo treatment with METH, which was associated with behavioral sensitization, caused a PKC-dependent astrocytic activation in the cingulate cortex and nucleus accumbens of mice. These findings provide direct evidence that METH induces a long-lasting astrocytic activation and behavioral sensitization through the stimulation of PKC in the rodent brain. In contrast, MRP produced a reversible activation of astrocytes via neuronal PKC and a reversibility of behavioral sensitization. This information can break through the definition of drugs of abuse and the misleading of concept that morphine produces a long-lasting neurotoxicity.
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Affiliation(s)
- Minoru Narita
- Department of Toxicology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, Ebara, Tokyo, Japan.
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24
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Ensslen-Craig SE, Brady-Kalnay SM. PTP mu expression and catalytic activity are required for PTP mu-mediated neurite outgrowth and repulsion. Mol Cell Neurosci 2005; 28:177-88. [PMID: 15607952 DOI: 10.1016/j.mcn.2004.08.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2004] [Revised: 08/10/2004] [Accepted: 08/25/2004] [Indexed: 12/22/2022] Open
Abstract
Cell adhesion molecules (CAMs) regulate neural development via both homophilic and heterophilic binding interactions. Various members of the receptor protein tyrosine phosphatase (RPTP) subfamily of CAMs mediate neurite outgrowth, yet in many cases, their ligands remain unknown. However, the PTP mu subfamily members are homophilic binding proteins. PTP mu is a growth-permissive substrate for nasal retinal ganglion cell (RGC) neurites and a growth inhibitory substrate for temporal RGC neurites. Whether PTP mu regulates these distinct behaviors via homophilic or heterophilic binding interactions is not currently known. In this manuscript, we demonstrate that PTP mu influences RGC axon guidance behaviors only in the E8 retina and not earlier in development. In addition, we demonstrate that PTP mu is permissive only for neurites from ventral-nasal retina and is repulsive to neurites from all other retinal quadrants. Furthermore, we show that PTP mu-mediated nasal neurite outgrowth and temporal repulsion require PTP mu expression and catalytic activity. These results are consistent with PTP mu homophilic binding generating a tyrosine phosphatase-dependent signal that ultimately leads to axon outgrowth or repulsion and that PTP mu's role in regulating axon guidance may be tightly regulated developmentally. In summary, these data demonstrate that PTP mu expression and catalytic activity are important in vertebrate axon guidance.
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Affiliation(s)
- Sonya E Ensslen-Craig
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, OH 44106-7960, USA
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25
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Carulli D, Laabs T, Geller HM, Fawcett JW. Chondroitin sulfate proteoglycans in neural development and regeneration. Curr Opin Neurobiol 2005; 15:116-20. [PMID: 15721753 DOI: 10.1016/j.conb.2005.01.014] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Proteoglycans are of two main types, chondroitin sulfate (CSPGs) and heparin sulfate (HSPGs). The CSPGs act mainly as barrier-forming molecules, whereas the HSPGs stabilise the interactions of receptors and ligands. During development CSPGs pattern cell migration, axon growth pathways and axon terminations. Later in development and in adulthood CSPGs associate with some classes of neuron and control plasticity. After damage to the nervous system, CSPGs are the major axon growth inhibitory component of the glial scar tissue that blocks successful regeneration. CSPGs have a variety of roles in the nervous system, including binding to molecules and blocking their action, presenting molecules to cells and axons, localising active molecules to particular sites and presenting growth factors to their receptors.
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Affiliation(s)
- Daniela Carulli
- Cambridge University Centre for Brain Repair, Robinson Way, Cambridge CB2 2PY, UK
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26
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Rolls A, Avidan H, Cahalon L, Schori H, Bakalash S, Litvak V, Lev S, Lider O, Schwartz M. A disaccharide derived from chondroitin sulphate proteoglycan promotes central nervous system repair in rats and mice. Eur J Neurosci 2004; 20:1973-83. [PMID: 15450076 DOI: 10.1111/j.1460-9568.2004.03676.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Chondroitin sulphate proteoglycan (CSPG) inhibits axonal regeneration in the central nervous system (CNS) and its local degradation promotes repair. We postulated that the enzymatic degradation of CSPG generates reparative products. Here we show that an enzymatic degradation product of CSPG, a specific disaccharide (CSPG-DS), promoted CNS recovery by modulating both neuronal and microglial behaviour. In neurons, acting via a mechanism that involves the PKCalpha and PYK2 intracellular signalling pathways, CSPG-DS induced neurite outgrowth and protected against neuronal toxicity and axonal collapse in vitro. In microglia, via a mechanism that involves ERK1/2 and PYK2, CSPG-DS evoked a response that allowed these cells to manifest a neuroprotective phenotype ex vivo. In vivo, systemically or locally injected CSPG-DS protected neurons in mice subjected to glutamate or aggregated beta-amyloid intoxication. Our results suggest that treatment with CSPG-DS might provide a way to promote post-traumatic recovery, via multiple cellular targets.
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Affiliation(s)
- Asya Rolls
- Department of Neurobiology, The Weizmann Institute of Science, 76100 Rehovot, Israel
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27
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Ensslen SE, Brady-Kalnay SM. PTPmu signaling via PKCdelta is instructive for retinal ganglion cell guidance. Mol Cell Neurosci 2004; 25:558-71. [PMID: 15080886 DOI: 10.1016/j.mcn.2003.12.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2003] [Revised: 11/24/2003] [Accepted: 12/03/2003] [Indexed: 01/03/2023] Open
Abstract
The receptor protein tyrosine phosphatase (RPTP) PTPmu mediates distinct cellular responses in nasal and temporal retinal ganglion cell (RGC) axons. PTPmu is permissive for nasal RGC neurite outgrowth and inhibitory to temporal RGCs. In addition, PTPmu causes preferential temporal growth cone collapse. Previous studies demonstrated that PTPmu associates with the scaffolding protein RACK1 and the protein kinase C-delta (PKCdelta) isoform in chick retina and that PKCdelta activity is required for PTPmu-mediated RGC outgrowth. Using in vitro stripe and collapse assays, we find that PKCdelta activity is required for both inhibitory and permissive responses of RGCs to PTPmu, with higher levels of PKCdelta activation associated with temporal growth cone collapse and repulsion. A potential mechanism for differential PKCdelta activation is due to the gradient of PTPmu expression in the retina. PTPmu is expressed in a high temporal, low nasal step gradient in the retina. In support of this, overexpression of exogenous PTPmu in nasal neurites results in a phenotypic switch from permissive to repulsive in response to PTPmu. Together, these results suggest that the differential expression of PTPmu within the retina is instructive for RGC guidance and that the magnitude of PKCdelta activation in response to PTPmu signaling results in the distinct cellular behaviors of nasal and temporal RGCs.
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Affiliation(s)
- Sonya E Ensslen
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4960, USA
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28
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Pascale A, Alkon DL, Grimaldi M. Translocation of protein kinase C-betaII in astrocytes requires organized actin cytoskeleton and is not accompanied by synchronous RACK1 relocation. Glia 2004; 46:169-82. [PMID: 15042584 DOI: 10.1002/glia.10354] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Protein kinase C (PKC)-betaII is the most abundant PKC isoform in astrocytes. Upon activation, this isoform of PKC translocates from the cytosol to the plasma membrane (PM). In this study, we investigated in astrocytes the modality of PKC-betaII translocation as far as the participation of the receptor for activated C kinase-1 (RACK1) and the requirement for intact cytoskeleton in the process. In astrocytes, Western blots and immunocytochemistry coupled to confocal microscopic quantitative analysis showed that after 5 min of phorbol-12-myristate-13-acetate (PMA) exposure, native PKC-betaII, but not PKC-betaI, is relocated efficiently from the cytosol to the PM. Translocation of PKC-betaII was not associated with synchronous RACK1 relocation. Furthermore, the quantity of PM-associated PKC-betaII that co-immunoprecipitated with PM-bound RACK1 increased following PMA exposure, indicating a post activation binding of the two proteins in the PM. Because RACK1 and PKC-betaII relocation seemed not to be synchronous, we hypothesized that an intermediate interaction with the cytoskeleton was taking place. In fact, we were able to show that pharmacological disruption of actin-based cytoskeleton greatly deranged PKC-betaII translocation to the PM. The requirement for intact actin cytoskeleton was specific, because depolymerization of tubulin had no effect on the ability of the kinase to translocate to the PM. These results indicate that in astrocytes, RACK1 and PKC-betaII synchronous relocation is not essential for relocation of PKC-betaII to the PM. In addition, we show for the first time that the integrity of the actin cytoskeleton plays a specific role in PKC-betaII movements in these cells. We hypothesize that in glial cells, rapidly occurring changes of actin cytoskeleton arrangement may be involved in the fast reprogramming of PKC targeting to specific PM location to phosphorylate substrates in different cellular locations.
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Affiliation(s)
- Alessia Pascale
- Laboratory of Adaptive Systems, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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29
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Abstract
In the present study, the influence of astrocyte alignment on the direction and length of regenerating neurites was examined in vitro. Astrocytes were experimentally manipulated by different approaches to create longitudinally aligned monolayers. When cultured on the aligned monolayers, dorsal root ganglion neurites grew parallel to the long axis of the aligned astrocytes and were significantly longer than controls. Engineered monolayers expressed linear arrays of fibronectin, laminin, neural cell adhesion molecule, and chondroitin sulfate proteoglycan that were organized parallel to one another, suggesting that a particular spatial arrangement of these molecules on the astrocyte surface may be necessary to direct nerve regeneration in vivo. In contrast, no bias in directional outgrowth was observed for neurites growing on unorganized monolayers. The results suggest that altering the organization of astrocytes and their scar-associated matrix at the lesion site may be used to influence the direction and the length of adjacent regenerating axons in the damaged brain and spinal cord.
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Affiliation(s)
- Roy Biran
- The Keck Center for Tissue Engineering, Department of Bioengineering, University of Utah, Salt Lake City, UT 84112, USA
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30
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Abstract
Injuries to the spinal cord that result in disruption of axonal continuity have devastating consequences for injured patients. Current therapies that use biologically active agents to promote neuronal survival and/or growth have had modest success in allowing injured neurons to regrow through the area of the lesion. Strategies for successful regeneration will require an engineering approach. We propose the design of cell-free grafts of biocompatible materials to build a bridge across the injured area through which axons can regenerate. There are three critical regions of this bridge: the on-ramp, the surface of the bridge itself, and the off-ramp. Each of these regions has specific design requirements, which, if met, can promote regeneration of axons in the injured spinal cord. These requirements, and proposed solutions, are discussed.
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Affiliation(s)
- Herbert M Geller
- Division of Intramural Research, National Heart, Lung and Blood Institute, Bethesda, Maryland 20892, USA
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