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Berillo O, Huo KG, Richer C, Fraulob-Aquino JC, Briet M, Lipman ML, Sinnett D, Paradis P, Schiffrin EL. Distinct transcriptomic profile of small arteries of hypertensive patients with chronic kidney disease identified miR-338-3p targeting GPX3 and PTPRS. J Hypertens 2022; 40:1394-1405. [PMID: 35703228 DOI: 10.1097/hjh.0000000000003160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVE Hypertension is associated with vascular injury, which contributes to end-organ damage. MicroRNAs regulating mRNAs have been shown to play a role in vascular injury in hypertensive mice. We aimed to identify differentially expressed microRNAs and their mRNA targets in small arteries of hypertensive patients with/without chronic kidney disease (CKD) to shed light on the pathophysiological molecular mechanisms of vascular remodeling. METHODS AND RESULTS Normotensive individuals and hypertensive patients with/without CKD were recruited ( n = 15-16 per group). Differentially expressed microRNAs and mRNAs were identified uniquely associated with hypertension (microRNAs: 10, mRNAs: 68) or CKD (microRNAs: 68, mRNAs: 395), and in both groups (microRNAs: 2, mRNAs: 32) with a P less than 0.05 and a fold change less than or greater than 1.3 in subcutaneous small arteries ( n = 14-15). One of the top three differentially expressed microRNAs, miR-338-3p that was down-regulated in CKD, presented the best correlation between RNA sequencing and reverse transcription-quantitative PCR (RT-qPCR, R2 = 0.328, P < 0.001). Profiling of human aortic vascular cells showed that miR-338-3p was mostly expressed in endothelial cells. Two of the selected top nine up-regulated miR-338-3p predicted targets, glutathione peroxidase 3 ( GPX3 ) and protein tyrosine phosphatase receptor type S ( PTPRS ), were validated with mimics by RT-qPCR in human aortic endothelial cells ( P < 0.05) and by a luciferase assay in HEK293T cells ( P < 0.05). CONCLUSION A distinct transcriptomic profile was observed in gluteal subcutaneous small arteries of hypertensive patients with CKD. Down-regulated miR-338-3p could contribute to GPX3 and PTPRS up-regulation via the canonical microRNA targeting machinery in hypertensive patients with CKD. http://links.lww.com/HJH/C27.
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Affiliation(s)
- Olga Berillo
- Hypertension and Vascular Research Unit, Lady Davis Institute for Medical Research
| | - Ku-Geng Huo
- Hypertension and Vascular Research Unit, Lady Davis Institute for Medical Research
| | - Chantal Richer
- Division of Hematology-Oncology, Research Center, CHU Ste-Justine
| | | | - Marie Briet
- Hypertension and Vascular Research Unit, Lady Davis Institute for Medical Research
- INSERM U1083, CNRS UMR 6214, Centre Hospitalo-Universitaire d'Angers, Université d'Angers, Angers, France
| | - Mark L Lipman
- Hypertension and Vascular Research Unit, Lady Davis Institute for Medical Research
- Department of Medicine, Sir Mortimer B. Davis-Jewish General Hospital, McGill University
| | - Daniel Sinnett
- Division of Hematology-Oncology, Research Center, CHU Ste-Justine
- Department of Pediatrics, Faculty of Medicine, Université de Montréal, Montréal, Canada
| | - Pierre Paradis
- Hypertension and Vascular Research Unit, Lady Davis Institute for Medical Research
| | - Ernesto L Schiffrin
- Hypertension and Vascular Research Unit, Lady Davis Institute for Medical Research
- Department of Medicine, Sir Mortimer B. Davis-Jewish General Hospital, McGill University
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2
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Cornejo F, Cortés BI, Findlay GM, Cancino GI. LAR Receptor Tyrosine Phosphatase Family in Healthy and Diseased Brain. Front Cell Dev Biol 2021; 9:659951. [PMID: 34966732 PMCID: PMC8711739 DOI: 10.3389/fcell.2021.659951] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 11/17/2021] [Indexed: 11/23/2022] Open
Abstract
Protein phosphatases are major regulators of signal transduction and they are involved in key cellular mechanisms such as proliferation, differentiation, and cell survival. Here we focus on one class of protein phosphatases, the type IIA Receptor-type Protein Tyrosine Phosphatases (RPTPs), or LAR-RPTP subfamily. In the last decade, LAR-RPTPs have been demonstrated to have great importance in neurobiology, from neurodevelopment to brain disorders. In vertebrates, the LAR-RPTP subfamily is composed of three members: PTPRF (LAR), PTPRD (PTPδ) and PTPRS (PTPσ), and all participate in several brain functions. In this review we describe the structure and proteolytic processing of the LAR-RPTP subfamily, their alternative splicing and enzymatic regulation. Also, we review the role of the LAR-RPTP subfamily in neural function such as dendrite and axon growth and guidance, synapse formation and differentiation, their participation in synaptic activity, and in brain development, discussing controversial findings and commenting on the most recent studies in the field. Finally, we discuss the clinical outcomes of LAR-RPTP mutations, which are associated with several brain disorders.
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Affiliation(s)
- Francisca Cornejo
- Center for Integrative Biology, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Bastián I Cortés
- Center for Integrative Biology, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Greg M Findlay
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Gonzalo I Cancino
- Center for Integrative Biology, Facultad de Ciencias, Universidad Mayor, Santiago, Chile.,Escuela de Biotecnología, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
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3
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Roy A, Pathak Z, Kumar H. Strategies to neutralize RhoA/ROCK pathway after spinal cord injury. Exp Neurol 2021; 343:113794. [PMID: 34166685 DOI: 10.1016/j.expneurol.2021.113794] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/01/2021] [Accepted: 06/19/2021] [Indexed: 01/22/2023]
Abstract
Regeneration is bungled following CNS injuries, including spinal cord injury (SCI). Inherent decay of permissive conditions restricts the regrowth of the mature CNS after an injury. Hypertrophic scarring, insignificant intrinsic axon-growth activity, and axon-growth inhibitory molecules such as myelin inhibitors and scar inhibitors constitute a significant hindrance to spinal cord repair. Besides these molecules, a combined absence of various mechanisms responsible for axonal regeneration is the main reason behind the dereliction of the adult CNS to regenerate. The neutralization of specific inhibitors/proteins by stymieing antibodies or encouraging enzymatic degradation results in improved axon regeneration. Previous efforts to induce regeneration after SCI have stimulated axonal development in or near lesion sites, but not beyond them. Several pathways are responsible for the axonal growth obstruction after a CNS injury, including SCI. Herein, we summarize the axonal, glial, and intrinsic factor which impedes the regeneration. We have also discussed the methods to stabilize microtubules and through this to maintain the proper cytoskeletal dynamics of growth cone as disorganized microtubules lead to the failure of axonal regeneration. Moreover, we primarily focus on diverse inhibitors of axonal growth and molecular approaches to counteract them and their downstream intracellular signaling through the RhoA/ROCK pathway.
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Affiliation(s)
- Abhishek Roy
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat, India
| | - Zarna Pathak
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat, India
| | - Hemant Kumar
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat, India.
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4
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Shahsavani N, Kataria H, Karimi-Abdolrezaee S. Mechanisms and repair strategies for white matter degeneration in CNS injury and diseases. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166117. [PMID: 33667627 DOI: 10.1016/j.bbadis.2021.166117] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/22/2021] [Accepted: 02/23/2021] [Indexed: 12/14/2022]
Abstract
White matter degeneration is an important pathophysiological event of the central nervous system that is collectively characterized by demyelination, oligodendrocyte loss, axonal degeneration and parenchymal changes that can result in sensory, motor, autonomic and cognitive impairments. White matter degeneration can occur due to a variety of causes including trauma, neurotoxic exposure, insufficient blood flow, neuroinflammation, and developmental and inherited neuropathies. Regardless of the etiology, the degeneration processes share similar pathologic features. In recent years, a plethora of cellular and molecular mechanisms have been identified for axon and oligodendrocyte degeneration including oxidative damage, calcium overload, neuroinflammatory events, activation of proteases, depletion of adenosine triphosphate and energy supply. Extensive efforts have been also made to develop neuroprotective and neuroregenerative approaches for white matter repair. However, less progress has been achieved in this area mainly due to the complexity and multifactorial nature of the degeneration processes. Here, we will provide a timely review on the current understanding of the cellular and molecular mechanisms of white matter degeneration and will also discuss recent pharmacological and cellular therapeutic approaches for white matter protection as well as axonal regeneration, oligodendrogenesis and remyelination.
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Affiliation(s)
- Narjes Shahsavani
- Department of Physiology and Pathophysiology, Regenerative Medicine Program, Spinal Cord Research Centre, Children's Hospital Research Institute of Manitoba, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Hardeep Kataria
- Department of Physiology and Pathophysiology, Regenerative Medicine Program, Spinal Cord Research Centre, Children's Hospital Research Institute of Manitoba, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Soheila Karimi-Abdolrezaee
- Department of Physiology and Pathophysiology, Regenerative Medicine Program, Spinal Cord Research Centre, Children's Hospital Research Institute of Manitoba, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada.
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5
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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: 36] [Impact Index Per Article: 9.0] [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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Han KA, Lee HY, Lim D, Shin J, Yoon TH, Lee C, Rhee JS, Liu X, Um JW, Choi SY, Ko J. PTPσ Controls Presynaptic Organization of Neurotransmitter Release Machinery at Excitatory Synapses. iScience 2020; 23:101203. [PMID: 32516721 PMCID: PMC7284068 DOI: 10.1016/j.isci.2020.101203] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 05/04/2020] [Accepted: 05/22/2020] [Indexed: 12/16/2022] Open
Abstract
Leukocyte common antigen-related receptor tyrosine phosphatases (LAR-RPTPs) are evolutionarily conserved presynaptic organizers. The synaptic role of vertebrate LAR-RPTPs in vivo, however, remains unclear. In the current study, we analyzed the synaptic role of PTPσ using newly generated, single conditional knockout (cKO) mice targeting PTPσ. We found that the number of synapses was reduced in PTPσ cKO cultured neurons in association with impaired excitatory synaptic transmission, abnormal vesicle localization, and abnormal synaptic ultrastructure. Strikingly, loss of presynaptic PTPσ reduced neurotransmitter release prominently at excitatory synapses, concomitant with drastic reductions in excitatory innervations onto postsynaptic target areas in vivo. Furthermore, loss of presynaptic PTPσ in hippocampal CA1 pyramidal neurons had no impact on postsynaptic glutamate receptor responses in subicular pyramidal neurons. Postsynaptic PTPσ deletion had no effect on excitatory synaptic strength. Taken together, these results demonstrate that PTPσ is a bona fide presynaptic adhesion molecule that controls neurotransmitter release and excitatory inputs. Conditional PTPσ KO produces specifically impaired presynaptic functions Presynaptic PTPσ regulates glutamate release efficiency Presynaptic PTPσ does not transsynaptically regulate postsynaptic receptor responses
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Affiliation(s)
- Kyung Ah Han
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea; Core Protein Resources Center, DGIST, 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Hee-Yoon Lee
- Department of Physiology and Neuroscience, Dental Research Institute, Seoul National University School of Dentistry, Seoul 03080, Korea
| | - Dongseok Lim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Jungsu Shin
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Taek Han Yoon
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Chooungku Lee
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen 37075, Germany
| | - Jeong-Seop Rhee
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen 37075, Germany
| | - Xinran Liu
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Ji Won Um
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea; Core Protein Resources Center, DGIST, 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Se-Young Choi
- Department of Physiology and Neuroscience, Dental Research Institute, Seoul National University School of Dentistry, Seoul 03080, Korea.
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea.
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7
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Baek KW, Jung YK, Kim JS, Park JS, Hah YS, Kim SJ, Yoo JI. Rodent Model of Muscular Atrophy for Sarcopenia Study. J Bone Metab 2020; 27:97-110. [PMID: 32572370 PMCID: PMC7297619 DOI: 10.11005/jbm.2020.27.2.97] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/15/2020] [Accepted: 05/16/2020] [Indexed: 12/25/2022] Open
Abstract
The hallmark symptom of sarcopenia is the loss of muscle mass and strength without the loss of overall body weight. Sarcopenia patients are likely to have worse clinical outcomes and higher mortality than do healthy individuals. The sarcopenia population shows an annual increase of ~0.8% in the population after age 50, and the prevalence rate is rapidly increasing with the recent worldwide aging trend. Based on International Classification of Diseases, Tenth Revision, a global classification of disease published by the World Health Organization, issued the disease code (M62.84) given to sarcopenia in 2016. Therefore, it is expected that the study of sarcopenia will be further activated based on the classification of disease codes in the aging society. Several epidemiological studies and meta-analyses have looked at the correlation between the prevalence of sarcopenia and several environmental factors. In addition, studies using cell lines and rodents have been done to understand the biological mechanism of sarcopenia. Laboratory rodent models are widely applicable in sarcopenia studies because of the advantages of time savings, cost saving, and various analytical applications that could not be used for human subjects. The rodent models that can be applied to the sarcopenia research are diverse, but a simple and fast method that can cause atrophy or aging is preferred. Therefore, we will introduce various methods of inducing muscular atrophy in rodent models to be applied to the study of sarcopenia.
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Affiliation(s)
- Kyung-Wan Baek
- Department of Physical Education, Gyeongsang National University, Jinju, Korea
- Department of Orthopaedic Surgery, Gyoengsang National University Hospital, Gyeongsang National University, Jinju, Korea
| | - Youn-Kwan Jung
- Biomedical Research Institute, Gyoengsang National University Hospital, Gyeongsang National University, Jinju, Korea
| | - Ji-Seok Kim
- Department of Physical Education, Gyeongsang National University, Jinju, Korea
| | - Jin Sung Park
- Department of Orthopaedic Surgery, Gyoengsang National University Hospital, Gyeongsang National University, Jinju, Korea
| | - Young-Sool Hah
- Biomedical Research Institute, Gyoengsang National University Hospital, Gyeongsang National University, Jinju, Korea
| | - So-Jeong Kim
- Department of Convergence of Medical Sciences, Gyeongsang National University, Jinju, Korea
| | - Jun-Il Yoo
- Department of Orthopaedic Surgery, Gyoengsang National University Hospital, Gyeongsang National University, Jinju, Korea
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8
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Rodemer W, Zhang G, Sinitsa I, Hu J, Jin LQ, Li S, Selzer ME. PTPσ Knockdown in Lampreys Impairs Reticulospinal Axon Regeneration and Neuronal Survival After Spinal Cord Injury. Front Cell Neurosci 2020; 14:61. [PMID: 32265663 PMCID: PMC7096546 DOI: 10.3389/fncel.2020.00061] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 03/02/2020] [Indexed: 01/10/2023] Open
Abstract
Traumatic spinal cord injury (SCI) results in persistent functional deficits due to the lack of axon regeneration within the mammalian CNS. After SCI, chondroitin sulfate proteoglycans (CSPGs) inhibit axon regrowth via putative interactions with the LAR-family protein tyrosine phosphatases, PTPσ and LAR, localized on the injured axon tips. Unlike mammals, the sea lamprey, Petromyzon marinus, robustly recovers locomotion after complete spinal cord transection (TX). Behavioral recovery is accompanied by heterogeneous yet predictable anatomical regeneration of the lamprey's reticulospinal (RS) system. The identified RS neurons can be categorized as "good" or "bad" regenerators based on the likelihood that their axons will regenerate. Those neurons that fail to regenerate their axons undergo a delayed form of caspase-mediated cell death. Previously, this lab reported that lamprey PTPσ mRNA is selectively expressed in "bad regenerator" RS neurons, preceding SCI-induced caspase activation. Consequently, we hypothesized that PTPσ deletion would reduce retrograde cell death and promote axon regeneration. Using antisense morpholino oligomers (MOs), we knocked down PTPσ expression after TX and assessed the effects on axon regeneration, caspase activation, intracellular signaling, and behavioral recovery. Unexpectedly, PTPσ knockdown significantly impaired RS axon regeneration at 10 weeks post-TX, primarily due to reduced long-term neuron survival. Interestingly, cell loss was not preceded by an increase in caspase or p53 activation. Behavioral recovery was largely unaffected, although PTPσ knockdowns showed mild deficits in the recovery of swimming distance and latency to immobility during open field swim assays. Although the mechanism underlying the cell death following TX and PTPσ knockdown remains unknown, this study suggests that PTPσ is not a net negative regulator of long tract axon regeneration in lampreys.
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Affiliation(s)
- William Rodemer
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Guixin Zhang
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Isabelle Sinitsa
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
- College of Science and Technology, Temple University, Philadelphia, PA, United States
| | - Jianli Hu
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Li-qing Jin
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Shuxin Li
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
- Department of Anatomy and Cell Biology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Michael E. Selzer
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
- Department of Neurology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
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9
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Tran AP, Warren PM, Silver J. Regulation of autophagy by inhibitory CSPG interactions with receptor PTPσ and its impact on plasticity and regeneration after spinal cord injury. Exp Neurol 2020; 328:113276. [PMID: 32145250 DOI: 10.1016/j.expneurol.2020.113276] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 03/02/2020] [Accepted: 03/03/2020] [Indexed: 12/15/2022]
Abstract
Chondroitin sulfate proteoglycans (CSPGs), extracellular matrix molecules that increase dramatically following a variety of CNS injuries or diseases, have long been known for their potent capacity to curtail cell migrations as well as axon regeneration and sprouting. The inhibition can be conferred through binding to their major cognate receptor, Protein Tyrosine Phosphatase Sigma (PTPσ). However, the precise mechanisms downstream of receptor binding that mediate growth inhibition have remained elusive. Recently, CSPGs/PTPσ interactions were found to regulate autophagic flux at the axon growth cone by dampening the autophagosome-lysosomal fusion step. Because of the intense interest in autophagic phenomena in the regulation of a wide variety of critical cellular functions, we summarize here what is currently known about dysregulation of autophagy following spinal cord injury, and highlight this critical new mechanism underlying axon regeneration failure. Furthermore, we review how CSPGs/PTPσ interactions influence plasticity through autophagic regulation and how PTPσ serves as a switch to execute either axon outgrowth or synaptogenesis. This has exciting implications for the role CSPGs play not only in axon regeneration failure after spinal cord injury, but also in neurodegenerative diseases where, again, inhibitory CSPGs are upregulated.
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Affiliation(s)
- Amanda Phuong Tran
- Seattle Children's Hospital Research Institute, Integrative Center for Brain Research, Seattle, Washington, USA
| | - Philippa Mary Warren
- King's College London, Regeneration Group, The Wolfson Centre for Age-Related Diseases, Guy's Campus, London Bridge, London, UK
| | - Jerry Silver
- Case Western Reserve University, School of Medicine, Department of Neurosciences, Cleveland, OH, USA.
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Niknam P, Raoufy MR, Fathollahi Y, Javan M. Modulating proteoglycan receptor PTPσ using intracellular sigma peptide improves remyelination and functional recovery in mice with demyelinated optic chiasm. Mol Cell Neurosci 2019; 99:103391. [DOI: 10.1016/j.mcn.2019.103391] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 06/20/2019] [Accepted: 07/01/2019] [Indexed: 11/29/2022] Open
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11
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Wang XS, Chen X, Gu TW, Wang YX, Mi DG, Hu W. Axonotmesis-evoked plantar vasodilatation as a novel assessment of C-fiber afferent function after sciatic nerve injury in rats. Neural Regen Res 2019; 14:2164-2172. [PMID: 31397356 PMCID: PMC6788242 DOI: 10.4103/1673-5374.262595] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Quantitative assessment of the recovery of nerve function, especially sensory and autonomic nerve function, remains a challenge in the field of nerve regeneration research. We previously found that neural control of vasomotor activity could be potentially harnessed to evaluate nerve function. In the present study, five different models of left sciatic nerve injury in rats were established: nerve crush injury, nerve transection/suturing, nerve defect/autografting, nerve defect/conduit repair, and nerve defect/non-regeneration. Laser Doppler perfusion imaging was used to analyze blood perfusion of the hind feet. The toe pinch test and walking track analysis were used to assess sensory and motor functions of the rat hind limb, respectively. Transmission electron microscopy was used to observe the density of unmyelinated axons in the injured sciatic nerve. Our results showed that axonotmesis-evoked vasodilatation in the foot 6 months after nerve injury/repair recovered to normal levels in the nerve crush injury group and partially in the other three repair groups; whereas the nerve defect/non-regeneration group exhibited no recovery in vasodilatation. Furthermore, the recovery index of axonotmesis-evoked vasodilatation was positively correlated with toe pinch reflex scores and the density of unmyelinated nerve fibers in the regenerated nerve. As C-fiber afferents are predominantly responsible for dilatation of the superficial vasculature in the glabrous skin in rats, the present findings indicate that axonotmesis-evoked vasodilatation can be used as a novel way to assess C-afferent function recovery after peripheral nerve injury. This study was approved by the Ethics Committee for Laboratory Animals of Nantong University of China (approval No. 20130410-006) on April 10, 2013.
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Affiliation(s)
- Xue-Song Wang
- Department of Orthopedics, The Affiliated Hospital of Jiangnan University (The Third People's Hospital of Wuxi City), Wuxi, Jiangsu Province, China
| | - Xue Chen
- Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu Province, China
| | - Tian-Wen Gu
- Key Laboratory for Neuroregeneration of Ministry of Education and Co-innovation Center for Neuroregeneration of Jiangsu Province, Nantong University, Nantong, Jiangsu Province, China
| | - Ya-Xian Wang
- Key Laboratory for Neuroregeneration of Ministry of Education and Co-innovation Center for Neuroregeneration of Jiangsu Province, Nantong University, Nantong, Jiangsu Province, China
| | - Da-Guo Mi
- Department of Orthopedics, Nantong Hospital of Traditional Chinese Medicine, Nantong, Jiangsu Province, China
| | - Wen Hu
- Key Laboratory for Neuroregeneration of Ministry of Education and Co-innovation Center for Neuroregeneration of Jiangsu Province, Nantong University, Nantong, Jiangsu Province, China
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12
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Bomkamp C, Padmanabhan N, Karimi B, Ge Y, Chao JT, Loewen CJR, Siddiqui TJ, Craig AM. Mechanisms of PTPσ-Mediated Presynaptic Differentiation. Front Synaptic Neurosci 2019; 11:17. [PMID: 31191292 PMCID: PMC6540616 DOI: 10.3389/fnsyn.2019.00017] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 05/06/2019] [Indexed: 11/13/2022] Open
Abstract
Formation of synapses between neurons depends in part on binding between axonal and dendritic cell surface synaptic organizing proteins, which recruit components of the developing presynaptic and postsynaptic specializations. One of these presynaptic organizing molecules is protein tyrosine phosphatase σ (PTPσ). Although the protein domains involved in adhesion between PTPσ and its postsynaptic binding partners are known, the mechanisms by which it signals into the presynaptic neuron to recruit synaptic vesicles and other necessary components for regulated transmitter release are not well understood. One attractive candidate to mediate this function is liprin-α, a scaffolding protein with well-established roles at the synapse. We systematically mutated residues of the PTPσ intracellular region (ICR) and used the yeast dihydrofolate reductase (DHFR) protein complementation assay to screen for disrupted interactions between these mutant forms of PTPσ and its various binding partners. Using a molecular replacement strategy, we show that disrupting the interaction between PTPσ and liprin-α, but not between PTPσ and itself or another binding partner, caskin, abolishes presynaptic differentiation. Furthermore, phosphatase activity of PTPσ and binding to extracellular heparan sulfate (HS) proteoglycans are dispensable for presynaptic induction. Previous reports have suggested that binding between PTPσ and liprin-α is mediated by the PTPσ membrane-distal phosphatase-like domain. However, we provide evidence here that both of the PTPσ phosphatase-like domains mediate binding to liprin-α and are required for PTPσ-mediated presynaptic differentiation. These findings further our understanding of the mechanistic basis by which PTPσ acts as a presynaptic organizer.
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Affiliation(s)
- Claire Bomkamp
- Djavad Mowafaghian Centre for Brain Health, Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
| | - Nirmala Padmanabhan
- Health Sciences Centre, Kleysen Institute for Advanced Medicine, University of Manitoba, Winnipeg, MB, Canada.,Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.,The Children's Hospital Research Institute of Manitoba (CHRIM), Winnipeg, MB, Canada
| | - Benyamin Karimi
- Health Sciences Centre, Kleysen Institute for Advanced Medicine, University of Manitoba, Winnipeg, MB, Canada.,Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.,The Children's Hospital Research Institute of Manitoba (CHRIM), Winnipeg, MB, Canada
| | - Yuan Ge
- Djavad Mowafaghian Centre for Brain Health, Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
| | - Jesse T Chao
- Department of Cellular and Physiological Sciences, Faculty of Medicine, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Christopher J R Loewen
- Department of Cellular and Physiological Sciences, Faculty of Medicine, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Tabrez J Siddiqui
- Health Sciences Centre, Kleysen Institute for Advanced Medicine, University of Manitoba, Winnipeg, MB, Canada.,Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.,The Children's Hospital Research Institute of Manitoba (CHRIM), Winnipeg, MB, Canada
| | - Ann Marie Craig
- Djavad Mowafaghian Centre for Brain Health, Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
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13
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Alizadeh A, Dyck SM, Karimi-Abdolrezaee S. Traumatic Spinal Cord Injury: An Overview of Pathophysiology, Models and Acute Injury Mechanisms. Front Neurol 2019; 10:282. [PMID: 30967837 PMCID: PMC6439316 DOI: 10.3389/fneur.2019.00282] [Citation(s) in RCA: 587] [Impact Index Per Article: 117.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 03/05/2019] [Indexed: 12/11/2022] Open
Abstract
Traumatic spinal cord injury (SCI) is a life changing neurological condition with substantial socioeconomic implications for patients and their care-givers. Recent advances in medical management of SCI has significantly improved diagnosis, stabilization, survival rate and well-being of SCI patients. However, there has been small progress on treatment options for improving the neurological outcomes of SCI patients. This incremental success mainly reflects the complexity of SCI pathophysiology and the diverse biochemical and physiological changes that occur in the injured spinal cord. Therefore, in the past few decades, considerable efforts have been made by SCI researchers to elucidate the pathophysiology of SCI and unravel the underlying cellular and molecular mechanisms of tissue degeneration and repair in the injured spinal cord. To this end, a number of preclinical animal and injury models have been developed to more closely recapitulate the primary and secondary injury processes of SCI. In this review, we will provide a comprehensive overview of the recent advances in our understanding of the pathophysiology of SCI. We will also discuss the neurological outcomes of human SCI and the available experimental model systems that have been employed to identify SCI mechanisms and develop therapeutic strategies for this condition.
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Affiliation(s)
- Arsalan Alizadeh
- Regenerative Medicine Program, Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, Spinal Cord Research Center, University of Manitoba, Winnipeg, MB, Canada
| | - Scott Matthew Dyck
- Regenerative Medicine Program, Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, Spinal Cord Research Center, University of Manitoba, Winnipeg, MB, Canada
| | - Soheila Karimi-Abdolrezaee
- Regenerative Medicine Program, Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, Spinal Cord Research Center, University of Manitoba, Winnipeg, MB, Canada
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14
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Tran AP, Warren PM, Silver J. The Biology of Regeneration Failure and Success After Spinal Cord Injury. Physiol Rev 2018. [PMID: 29513146 DOI: 10.1152/physrev.00017.2017] [Citation(s) in RCA: 490] [Impact Index Per Article: 81.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Since no approved therapies to restore mobility and sensation following spinal cord injury (SCI) currently exist, a better understanding of the cellular and molecular mechanisms following SCI that compromise regeneration or neuroplasticity is needed to develop new strategies to promote axonal regrowth and restore function. Physical trauma to the spinal cord results in vascular disruption that, in turn, causes blood-spinal cord barrier rupture leading to hemorrhage and ischemia, followed by rampant local cell death. As subsequent edema and inflammation occur, neuronal and glial necrosis and apoptosis spread well beyond the initial site of impact, ultimately resolving into a cavity surrounded by glial/fibrotic scarring. The glial scar, which stabilizes the spread of secondary injury, also acts as a chronic, physical, and chemo-entrapping barrier that prevents axonal regeneration. Understanding the formative events in glial scarring helps guide strategies towards the development of potential therapies to enhance axon regeneration and functional recovery at both acute and chronic stages following SCI. This review will also discuss the perineuronal net and how chondroitin sulfate proteoglycans (CSPGs) deposited in both the glial scar and net impede axonal outgrowth at the level of the growth cone. We will end the review with a summary of current CSPG-targeting strategies that help to foster axonal regeneration, neuroplasticity/sprouting, and functional recovery following SCI.
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Affiliation(s)
- Amanda Phuong Tran
- Department of Neurosciences, Case Western Reserve University , Cleveland, Ohio ; and School of Biomedical Sciences, University of Leeds , Leeds , United Kingdom
| | - Philippa Mary Warren
- Department of Neurosciences, Case Western Reserve University , Cleveland, Ohio ; and School of Biomedical Sciences, University of Leeds , Leeds , United Kingdom
| | - Jerry Silver
- Department of Neurosciences, Case Western Reserve University , Cleveland, Ohio ; and School of Biomedical Sciences, University of Leeds , Leeds , United Kingdom
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15
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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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16
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Small molecule targeting of PTPs in cancer. Int J Biochem Cell Biol 2017; 96:171-181. [PMID: 28943273 DOI: 10.1016/j.biocel.2017.09.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 09/14/2017] [Accepted: 09/15/2017] [Indexed: 01/28/2023]
Abstract
Protein tyrosine phosphatases (PTPs) undeniably have a central role in the development and progression of human cancers. Historically, however, PTPs have not been viewed as privileged drug targets, and progress on identifying potent, selective, and cell-active small molecule PTP inhibitors has suffered accordingly. This situation is rapidly changing, however, due to biochemical advances in the study of PTPs and recent small molecule screening campaigns, which have identified potent and mechanistically diverse lead structures. These compounds are facilitating the exploration of the fundamental cellular processes controlled by PTPs in cancers, and could form the inflection point for new therapeutic paradigms for the treatment of a range of cancers. Herein, we review recent advances in the discovery and biological annotation of cancer-relevant small molecule PTP inhibitors.
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17
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Chondroitin sulfates and their binding molecules in the central nervous system. Glycoconj J 2017; 34:363-376. [PMID: 28101734 PMCID: PMC5487772 DOI: 10.1007/s10719-017-9761-z] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 12/31/2016] [Accepted: 01/04/2017] [Indexed: 01/05/2023]
Abstract
Chondroitin sulfate (CS) is the most abundant glycosaminoglycan (GAG) in the central nervous system (CNS) matrix. Its sulfation and epimerization patterns give rise to different forms of CS, which enables it to interact specifically and with a significant affinity with various signalling molecules in the matrix including growth factors, receptors and guidance molecules. These interactions control numerous biological and pathological processes, during development and in adulthood. In this review, we describe the specific interactions of different families of proteins involved in various physiological and cognitive mechanisms with CSs in CNS matrix. A better understanding of these interactions could promote a development of inhibitors to treat neurodegenerative diseases.
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18
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Huang Z, Gao Y, Sun Y, Zhang C, Yin Y, Shimoda Y, Watanabe K, Liu Y. NB-3 signaling mediates the cross-talk between post-traumatic spinal axons and scar-forming cells. EMBO J 2016; 35:1745-65. [PMID: 27192985 DOI: 10.15252/embj.201593460] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 04/12/2016] [Indexed: 11/09/2022] Open
Abstract
Little is known about the molecules mediating the cross-talk between post-traumatic axons and scar-forming cells after spinal cord injury. We found that a sustained NB-3 induction was simultaneously present in the terminations of post-traumatic corticospinal axons and scar-forming cells at the spinal lesion site, where they were in direct contact when axons tried to penetrate the glial scar. The regrowth of corticospinal axons was enhanced in vivo with NB-3 deficiency or interruption of NB-3 trans-homophilic interactions. Biochemical, in vitro and in vivo evidence demonstrated that NB-3 homophilically interacted in trans to initiate a growth inhibitory signal transduction from scar-forming cells to neurons by modulating mTOR activity via CHL1 and PTPσ. NB-3 deficiency promoted BMS scores, electrophysiological transmission, and synapse reformation between regenerative axons and neurons. Our findings demonstrate that NB-3 trans-homophilic interactions mediate the cross-talk between post-traumatic axons and scar-forming cells and impair the intrinsic growth ability of injured axons.
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Affiliation(s)
- Zhenhui Huang
- Institute of Neuroscience, Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Soochow University, Suzhou, China
| | - Yarong Gao
- Institute of Neuroscience, Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Soochow University, Suzhou, China
| | - Yuhui Sun
- Institute of Neuroscience, Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Soochow University, Suzhou, China
| | - Chao Zhang
- The Medical School of Lanzhou University, Lanzhou, China
| | - Yue Yin
- Institute of Neuroscience, Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Soochow University, Suzhou, China
| | - Yasushi Shimoda
- Department of Bioengineering, Nagaoka University of Technology, Niigata, Japan
| | | | - Yaobo Liu
- Institute of Neuroscience, Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Soochow University, Suzhou, China
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19
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Alizadeh A, Karimi-Abdolrezaee S. Microenvironmental regulation of oligodendrocyte replacement and remyelination in spinal cord injury. J Physiol 2016; 594:3539-52. [PMID: 26857216 DOI: 10.1113/jp270895] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 12/26/2015] [Indexed: 01/29/2023] Open
Abstract
Myelin is a proteolipid sheath enwrapping axons in the nervous system that facilitates signal transduction along the axons. In the central nervous system (CNS), oligodendrocytes are specialized glial cells responsible for myelin formation and maintenance. Following spinal cord injury (SCI), oligodendroglia cell death and myelin damage (demyelination) cause chronic axonal damage and irreparable loss of sensory and motor functions. Accumulating evidence shows that replacement of damaged oligodendrocytes and renewal of myelin (remyelination) are promising approaches to prevent axonal degeneration and restore function following SCI. Neural precursor cells (NPCs) and oligodendrocyte progenitor cells (OPCs) are two main resident cell populations in the spinal cord with innate capacities to foster endogenous oligodendrocyte replacement and remyelination. However, due to the hostile microenvironment of SCI, the regenerative capacity of these endogenous precursor cells is conspicuously restricted. Activated resident glia, along with infiltrating immune cells, are among the key modulators of secondary injury mechanisms that create a milieu impermissible to oligodendrocyte differentiation and remyelination. Recent studies have uncovered inhibitory roles for astrocyte-associated molecules such as matrix chondroitin sulfate proteoglycans (CSPGs), and a plethora of pro-inflammatory cytokines and neurotoxic factors produced by activated microglia/macrophages. The quality of axonal remyelination is additionally challenged by dysregulation of the supportive growth factors required for maturation of new oligodendrocytes and axo-oligodendrocyte signalling. Careful understanding of factors that modulate the activity of endogenous precursor cells in the injury microenvironment is a key step in developing efficient repair strategies for remyelination and functional recovery following SCI.
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Affiliation(s)
- Arsalan Alizadeh
- Regenerative Medicine Program, Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Soheila Karimi-Abdolrezaee
- Regenerative Medicine Program, Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Manitoba, Canada
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20
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Dyck SM, Alizadeh A, Santhosh KT, Proulx EH, Wu CL, Karimi-Abdolrezaee S. Chondroitin Sulfate Proteoglycans Negatively Modulate Spinal Cord Neural Precursor Cells by Signaling Through LAR and RPTPσ and Modulation of the Rho/ROCK Pathway. Stem Cells 2015; 33:2550-63. [PMID: 25703008 DOI: 10.1002/stem.1979] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 01/20/2015] [Indexed: 12/27/2022]
Abstract
Multipotent adult neural precursor cells (NPCs) have tremendous intrinsic potential to repair the damaged spinal cord. However, evidence shows that the regenerative capabilities of endogenous and transplanted NPCs are limited in the microenvironment of spinal cord injury (SCI). We previously demonstrated that injury-induced upregulation of matrix chondroitin sulfate proteoglycans (CSPGs) restricts the survival, migration, integration, and differentiation of NPCs following SCI. CSPGs are long-lasting components of the astroglial scar that are formed around the lesion. Our recent in vivo studies demonstrated that removing CSPGs from the SCI environment enhances the potential of transplanted and endogenous adult NPCs for spinal cord repair; however, the mechanisms by which CSPGs regulate NPCs remain unclear. In this study, using in vitro models recapitulating the extracellular matrix of SCI, we investigated the direct role of CSPGs in modulating the properties of adult spinal cord NPCs. We show that CSPGs significantly decrease NPCs growth, attachment, survival, proliferation, and oligodendrocytes differentiation. Moreover, using genetic models, we show that CSPGs regulate NPCs by signaling on receptor protein tyrosine phosphate sigma (RPTPσ) and leukocyte common antigen-related phosphatase (LAR). Intracellularly, CSPGs inhibitory effects are mediated through Rho/ROCK pathway and inhibition of Akt and Erk1/2 phosphorylation. Downregulation of RPTPσ and LAR and blockade of ROCK in NPCs attenuates the inhibitory effects of CSPGS. Our work provide novel evidence uncovering how upregulation of CSPGs challenges the response of NPCs in their post-SCI niche and identifies new therapeutic targets for enhancing NPC-based therapies for SCI repair.
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Affiliation(s)
- Scott M Dyck
- Department of Physiology and Pathophysiology, Regenerative Medicine Program, Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Arsalan Alizadeh
- Department of Physiology and Pathophysiology, Regenerative Medicine Program, Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Kallivalappil T Santhosh
- Department of Physiology and Pathophysiology, Regenerative Medicine Program, Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Evan H Proulx
- Department of Physiology and Pathophysiology, Regenerative Medicine Program, Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Chia-Lun Wu
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - Soheila Karimi-Abdolrezaee
- Department of Physiology and Pathophysiology, Regenerative Medicine Program, Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada.,Department of Biochemistry and Medical Genetics and Children's Hospital Research Institute of Manitoba, Winnipeg, Manitoba, Canada
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21
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Dyck SM, Karimi-Abdolrezaee S. Chondroitin sulfate proteoglycans: Key modulators in the developing and pathologic central nervous system. Exp Neurol 2015; 269:169-87. [PMID: 25900055 DOI: 10.1016/j.expneurol.2015.04.006] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 04/11/2015] [Accepted: 04/14/2015] [Indexed: 12/15/2022]
Abstract
Chondroitin Sulfate Proteoglycans (CSPGs) are a major component of the extracellular matrix in the central nervous system (CNS) and play critical role in the development and pathophysiology of the brain and spinal cord. Developmentally, CSPGs provide guidance cues for growth cones and contribute to the formation of neuronal boundaries in the developing CNS. Their presence in perineuronal nets plays a crucial role in the maturation of synapses and closure of critical periods by limiting synaptic plasticity. Following injury to the CNS, CSPGs are dramatically upregulated by reactive glia which form a glial scar around the lesion site. Increased level of CSPGs is a hallmark of all CNS injuries and has been shown to limit axonal plasticity, regeneration, remyelination, and conduction after injury. Additionally, CSPGs create a non-permissive milieu for cell replacement activities by limiting cell migration, survival and differentiation. Mounting evidence is currently shedding light on the potential benefits of manipulating CSPGs in combination with other therapeutic strategies to promote spinal cord repair and regeneration. Moreover, the recent discovery of multiple receptors for CSPGs provides new therapeutic targets for targeted interventions in blocking the inhibitory properties of CSPGs following injury. Here, we will provide an in depth discussion on the impact of CSPGs in normal and pathological CNS. We will also review the recent preclinical therapies that have been developed to target CSPGs in the injured CNS.
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Affiliation(s)
- Scott M Dyck
- Regenerative Medicine Program, Department of Physiology and the Spinal Cord Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Soheila Karimi-Abdolrezaee
- Regenerative Medicine Program, Department of Physiology and the Spinal Cord Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada.
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22
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Stoker AW. RPTPs in axons, synapses and neurology. Semin Cell Dev Biol 2014; 37:90-7. [PMID: 25234542 DOI: 10.1016/j.semcdb.2014.09.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/04/2014] [Accepted: 09/05/2014] [Indexed: 01/06/2023]
Abstract
Receptor-like protein tyrosine phosphatases represent a large protein family related to cell adhesion molecules, with diverse roles throughout neural development in vertebrates and invertebrates. This review focuses on their roles in axon growth, guidance and repair, as well as more recent findings demonstrating their key roles in pre-synaptic and post-synaptic maturation and function. These enzymes have been linked to memory and neuropsychiatric defects in loss-of-function rodent models, highlighting their potential as future drug targets.
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Affiliation(s)
- Andrew W Stoker
- Institute of Child Health, University College London, United Kingdom.
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23
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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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24
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Shen Y. Traffic lights for axon growth: proteoglycans and their neuronal receptors. Neural Regen Res 2014; 9:356-61. [PMID: 25206823 PMCID: PMC4146200 DOI: 10.4103/1673-5374.128236] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/08/2014] [Indexed: 01/19/2023] Open
Abstract
Axon growth is a central event in the development and post-injury plasticity of the nervous system. Growing axons encounter a wide variety of environmental instructions. Much like traffic lights in controlling the migrating axons, chondroitin sulfate proteoglycans (CSPGs) and heparan sulfate proteoglycans (HSPGs) often lead to "stop" and "go" growth responses in the axons, respectively. Recently, the LAR family and NgR family molecules were identified as neuronal receptors for CSPGs and HSPGs. These discoveries provided molecular tools for further study of mechanisms underlying axon growth regulation. More importantly, the identification of these proteoglycan receptors offered potential therapeutic targets for promoting post-injury axon regeneration.
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Affiliation(s)
- Yingjie Shen
- Department of Neuroscience and Center for Brain and Spinal Cord Repair, Wexner Medical Center, The Ohio State University, 460 w 12 Ave, Columbus, OH 43210, USA
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25
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Awakening the stalled axon - surprises in CSPG gradients. Exp Neurol 2014; 254:12-7. [PMID: 24424282 DOI: 10.1016/j.expneurol.2013.12.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 12/23/2013] [Accepted: 12/25/2013] [Indexed: 01/11/2023]
Abstract
The remarkably poor regeneration of axons seen after injury of the brain and spinal cord can result in permanent loss of neural function. This failure of meaningful regeneration has been attributed to both a low intrinsic growth potential of CNS neurons and extrinsic factors that actively block axon growth in the adult CNS. Injury exacerbates this situation by increasing the expression of and exposure to proteins that actively block axonal growth in the CNS. Much experimental efforts have been aimed at overcoming the extrinsic growth inhibitory environment of the injured brain and spinal cord. A recent publication in Experimental Neurology from Kuboyama and colleagues shows that activation of protein kinase A signaling is responsible for the stalling of axon growth in gradients of CNS inhibitory molecules. This observation is unexpected given the role of cAMP signaling in supporting intrinsic growth mechanisms, emphasizing the need to consider spatial and temporal aspects of intracellular signaling in future strategies for neural repair.
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26
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Functional regeneration beyond the glial scar. Exp Neurol 2014; 253:197-207. [PMID: 24424280 DOI: 10.1016/j.expneurol.2013.12.024] [Citation(s) in RCA: 477] [Impact Index Per Article: 47.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 12/18/2013] [Accepted: 12/24/2013] [Indexed: 12/14/2022]
Abstract
Astrocytes react to CNS injury by building a dense wall of filamentous processes around the lesion. Stromal cells quickly take up residence in the lesion core and synthesize connective tissue elements that contribute to fibrosis. Oligodendrocyte precursor cells proliferate within the lesion and entrap dystrophic axon tips. Here we review evidence that this aggregate scar acts as the major barrier to regeneration of axons after injury. We also consider several exciting new interventions that allow axons to regenerate beyond the glial scar, and discuss the implications of this work for the future of regeneration biology.
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27
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Protein tyrosine phosphatase σ targets apical junction complex proteins in the intestine and regulates epithelial permeability. Proc Natl Acad Sci U S A 2014; 111:693-8. [PMID: 24385580 DOI: 10.1073/pnas.1315017111] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Protein tyrosine phosphatase (PTP)σ (PTPRS) was shown previously to be associated with susceptibility to inflammatory bowel disease (IBD). PTPσ(-/-) mice exhibit an IBD-like phenotype in the intestine and show increased susceptibility to acute models of murine colitis. However, the function of PTPσ in the intestine is uncharacterized. Here, we show an intestinal epithelial barrier defect in the PTPσ(-/-) mouse, demonstrated by a decrease in transepithelial resistance and a leaky intestinal epithelium that was determined by in vivo tracer analysis. Increased tyrosine phosphorylation was observed at the plasma membrane of epithelial cells lining the crypts of the small bowel and colon of the PTPσ(-/-) mouse, suggesting the presence of PTPσ substrates in these regions. Using mass spectrometry, we identified several putative PTPσ intestinal substrates that were hyper-tyrosine-phosphorylated in the PTPσ(-/-) mice relative to wild type. Among these were proteins that form or regulate the apical junction complex, including ezrin. We show that ezrin binds to and is dephosphorylated by PTPσ in vitro, suggesting it is a direct PTPσ substrate, and identified ezrin-Y353/Y145 as important sites targeted by PTPσ. Moreover, subcellular localization of the ezrin phosphomimetic Y353E or Y145 mutants were disrupted in colonic Caco-2 cells, similar to ezrin mislocalization in the colon of PTPσ(-/-) mice following induction of colitis. Our results suggest that PTPσ is a positive regulator of intestinal epithelial barrier, which mediates its effects by modulating epithelial cell adhesion through targeting of apical junction complex-associated proteins (including ezrin), a process impaired in IBD.
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Discovery of novel protein tyrosine phosphatase sigma inhibitors through the virtual screening with modified scoring function. Med Chem Res 2013. [DOI: 10.1007/s00044-013-0713-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Integrating virtual and biochemical screening for protein tyrosine phosphatase inhibitor discovery. Methods 2013; 65:219-28. [PMID: 23969317 DOI: 10.1016/j.ymeth.2013.08.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 08/09/2013] [Accepted: 08/13/2013] [Indexed: 12/14/2022] Open
Abstract
Protein tyrosine phosphatases (PTPs) represent an important class of enzymes that mediate signal transduction and control diverse aspects of cell behavior. The importance of their activity is exemplified by their significant contribution to disease etiology with over half of all human PTP genes implicated in at least one disease. Small molecule inhibitors targeting individual PTPs are important biological tools, and are needed to fully characterize the function of these enzymes. Moreover, potent and selective PTP inhibitors hold the promise to transform the treatment of many diseases. While numerous methods exist to develop PTP-directed small molecules, we have found that complimentary use of both virtual (in silico) and biochemical (in vitro) screening approaches expedite compound identification and drug development. Here, we summarize methods pertinent to our work and others. Focusing on specific challenges and successes we have experienced, we discuss the considerable caution that must be taken to avoid enrichment of inhibitors that function by non-selective oxidation. We also discuss the utility of using "open" PTP structures to identify active-site directed compounds, a rather unconventional choice for virtual screening. When integrated closely, virtual and biochemical screening can be used in a productive workflow to identify small molecules targeting PTPs.
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Martin KR, Narang P, Xu Y, Kauffman AL, Petit J, Xu HE, Meurice N, MacKeigan JP. Identification of small molecule inhibitors of PTPσ through an integrative virtual and biochemical approach. PLoS One 2012. [PMID: 23185579 PMCID: PMC3502291 DOI: 10.1371/journal.pone.0050217] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
PTPσ is a dual-domain receptor type protein tyrosine phosphatase (PTP) with physiologically important functions which render this enzyme an attractive biological target. Specifically, loss of PTPσ has been shown to elicit a number of cellular phenotypes including enhanced nerve regeneration following spinal cord injury (SCI), chemoresistance in cultured cancer cells, and hyperactive autophagy, a process critical to cell survival and the clearance of pathological aggregates in neurodegenerative diseases. Owing to these functions, modulation of PTPσ may provide therapeutic value in a variety of contexts. Furthermore, a small molecule inhibitor would provide utility in discerning the cellular functions and substrates of PTPσ. To develop such molecules, we combined in silico modeling with in vitro phosphatase assays to identify compounds which effectively inhibit the enzymatic activity of PTPσ. Importantly, we observed that PTPσ inhibition was frequently mediated by oxidative species generated by compounds in solution, and we further optimized screening conditions to eliminate this effect. We identified a compound that inhibits PTPσ with an IC50 of 10 µM in a manner that is primarily oxidation-independent. This compound favorably binds the D1 active site of PTPσ in silico, suggesting it functions as a competitive inhibitor. This compound will serve as a scaffold structure for future studies designed to build selectivity for PTPσ over related PTPs.
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Affiliation(s)
- Katie R. Martin
- Laboratory of Systems Biology, Van Andel Research Institute, Grand Rapids, Michigan, United States of America
| | - Pooja Narang
- Mayo Clinic, Scottsdale, Arizona, United States of America
| | - Yong Xu
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan, United States of America
| | - Audra L. Kauffman
- Laboratory of Systems Biology, Van Andel Research Institute, Grand Rapids, Michigan, United States of America
| | - Joachim Petit
- Mayo Clinic, Scottsdale, Arizona, United States of America
| | - H. Eric Xu
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan, United States of America
| | | | - Jeffrey P. MacKeigan
- Laboratory of Systems Biology, Van Andel Research Institute, Grand Rapids, Michigan, United States of America
- * E-mail:
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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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32
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Discovery of potent inhibitors of receptor protein tyrosine phosphatase sigma through the structure-based virtual screening. Bioorg Med Chem Lett 2012; 22:6333-7. [DOI: 10.1016/j.bmcl.2012.08.081] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 08/09/2012] [Accepted: 08/22/2012] [Indexed: 11/22/2022]
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Chien PN, Ryu SE. Protein Tyrosine Phosphatase σ in Proteoglycan-Mediated Neural Regeneration Regulation. Mol Neurobiol 2012; 47:220-7. [DOI: 10.1007/s12035-012-8346-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 08/27/2012] [Indexed: 12/25/2022]
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34
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Horn KE, Xu B, Gobert D, Hamam BN, Thompson KM, Wu CL, Bouchard JF, Uetani N, Racine RJ, Tremblay ML, Ruthazer ES, Chapman CA, Kennedy TE. Receptor protein tyrosine phosphatase sigma regulates synapse structure, function and plasticity. J Neurochem 2012; 122:147-61. [PMID: 22519304 DOI: 10.1111/j.1471-4159.2012.07762.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The mechanisms that regulate synapse formation and maintenance are incompletely understood. In particular, relatively few inhibitors of synapse formation have been identified. Receptor protein tyrosine phosphatase σ (RPTPσ), a transmembrane tyrosine phosphatase, is widely expressed by neurons in developing and mature mammalian brain, and functions as a receptor for chondroitin sulfate proteoglycans that inhibits axon regeneration following injury. In this study, we address RPTPσ function in the mature brain. We demonstrate increased axon collateral branching in the hippocampus of RPTPσ null mice during normal aging or following chemically induced seizure, indicating that RPTPσ maintains neural circuitry by inhibiting axonal branching. Previous studies demonstrated a role for pre-synaptic RPTPσ promoting synaptic differentiation during development; however, subcellular fractionation revealed enrichment of RPTPσ in post-synaptic densities. We report that neurons lacking RPTPσ have an increased density of pre-synaptic varicosities in vitro and increased dendritic spine density and length in vivo. RPTPσ knockouts exhibit an increased frequency of miniature excitatory post-synaptic currents, and greater paired-pulse facilitation, consistent with increased synapse density but reduced synaptic efficiency. Furthermore, RPTPσ nulls exhibit reduced long-term potentiation and enhanced novel object recognition memory. We conclude that RPTPσ limits synapse number and regulates synapse structure and function in the mature CNS.
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Affiliation(s)
- Katherine E Horn
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
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35
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A sulfated carbohydrate epitope inhibits axon regeneration after injury. Proc Natl Acad Sci U S A 2012; 109:4768-73. [PMID: 22411830 DOI: 10.1073/pnas.1121318109] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Chondroitin sulfate proteoglycans (CSPGs) represent a major barrier to regenerating axons in the central nervous system (CNS), but the structural diversity of their polysaccharides has hampered efforts to dissect the structure-activity relationships underlying their physiological activity. By taking advantage of our ability to chemically synthesize specific oligosaccharides, we demonstrate that a sugar epitope on CSPGs, chondroitin sulfate-E (CS-E), potently inhibits axon growth. Removal of the CS-E motif significantly attenuates the inhibitory activity of CSPGs on axon growth. Furthermore, CS-E functions as a protein recognition element to engage receptors including the transmembrane protein tyrosine phosphatase PTPσ, thereby triggering downstream pathways that inhibit axon growth. Finally, masking the CS-E motif using a CS-E-specific antibody reversed the inhibitory activity of CSPGs and stimulated axon regeneration in vivo. These results demonstrate that a specific sugar epitope within chondroitin sulfate polysaccharides can direct important physiological processes and provide new therapeutic strategies to regenerate axons after CNS injury.
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36
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Wang F, Wolfson SN, Gharib A, Sagasti A. LAR receptor tyrosine phosphatases and HSPGs guide peripheral sensory axons to the skin. Curr Biol 2012; 22:373-82. [PMID: 22326027 PMCID: PMC3298620 DOI: 10.1016/j.cub.2012.01.040] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 01/06/2012] [Accepted: 01/20/2012] [Indexed: 11/20/2022]
Abstract
BACKGROUND Peripheral axons of somatosensory neurons innervate the skin early in development to detect touch stimuli. Embryological experiments had suggested that the skin produces guidance cues that attract sensory axons, but neither the attractants nor their neuronal receptors had previously been identified. RESULTS To investigate peripheral axon navigation to the skin, we combined live imaging of developing zebrafish Rohon-Beard (RB) neurons with molecular loss-of-function manipulations. Simultaneously knocking down two members of the leukocyte antigen-related (LAR) family of receptor tyrosine phosphatases expressed in RB neurons, or inhibiting their function with dominant-negative proteins, misrouted peripheral axons to internal tissues. Time-lapse imaging indicated that peripheral axon guidance, rather than outgrowth or maintenance, was defective in LAR-deficient neurons. Peripheral axons displayed a similar misrouting phenotype in mutants defective in heparan sulfate proteoglycan (HSPG) production and avoided regions in which HSPGs were locally degraded. CONCLUSIONS HSPGs and LAR family receptors are required for sensory axon guidance to the skin. Together, our results support a model in which peripheral HSPGs are attractive ligands for LAR receptors on RB neurons.
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Affiliation(s)
- Fang Wang
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA.
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37
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Hu W, Yang M, Chang J, Shen Z, Gu T, Deng A, Gu X. Laser doppler perfusion imaging of skin territory to reflect autonomic functional recovery following sciatic nerve autografting repair in rats. Microsurgery 2012; 32:136-43. [DOI: 10.1002/micr.20974] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 09/27/2011] [Accepted: 09/28/2011] [Indexed: 12/27/2022]
Affiliation(s)
- Wen Hu
- Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, People's Republic of China
| | - Min Yang
- Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, People's Republic of China
| | - Jingjian Chang
- School of Medicine, Nantong University, Nantong, Jiangsu Province, People's Republic of China
| | - Zhongyi Shen
- School of Medicine, Nantong University, Nantong, Jiangsu Province, People's Republic of China
| | - Tianwen Gu
- School of Medicine, Nantong University, Nantong, Jiangsu Province, People's Republic of China
| | - Aidong Deng
- Department of Hand Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, People's Republic of China
| | - Xiaosong Gu
- Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, People's Republic of China
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38
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Abstract
Axon regeneration is a fundamental problem facing neuroscientists and clinicians. Failure of axon regeneration is caused by both extrinsic and intrinsic mechanisms. New techniques to examine gene expression such as Next Generation Sequencing of the Transcriptome (RNA-Seq) drastically increase our knowledge of both gene expression complexity (RNA isoforms) and gene expression regulation. By utilizing RNA-Seq, gene expression can now be defined at the level of isoforms, an essential step for understanding the mechanisms governing cell identity, growth and ultimately cellular responses to injury and disease.
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Affiliation(s)
- Jessica K Lerch
- The Miami Project to Cure Paralysis, The University of Miami, Miami, FL, USA
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39
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Coles CH, Shen Y, Tenney AP, Siebold C, Sutton GC, Lu W, Gallagher JT, Jones EY, Flanagan JG, Aricescu AR. Proteoglycan-specific molecular switch for RPTPσ clustering and neuronal extension. Science 2011; 332:484-8. [PMID: 21454754 PMCID: PMC3154093 DOI: 10.1126/science.1200840] [Citation(s) in RCA: 248] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Heparan and chondroitin sulfate proteoglycans (HSPGs and CSPGs, respectively) regulate numerous cell surface signaling events, with typically opposite effects on cell function. CSPGs inhibit nerve regeneration through receptor protein tyrosine phosphatase sigma (RPTPσ). Here we report that RPTPσ acts bimodally in sensory neuron extension, mediating CSPG inhibition and HSPG growth promotion. Crystallographic analyses of a shared HSPG-CSPG binding site reveal a conformational plasticity that can accommodate diverse glycosaminoglycans with comparable affinities. Heparan sulfate and analogs induced RPTPσ ectodomain oligomerization in solution, which was inhibited by chondroitin sulfate. RPTPσ and HSPGs colocalize in puncta on sensory neurons in culture, whereas CSPGs occupy the extracellular matrix. These results lead to a model where proteoglycans can exert opposing effects on neuronal extension by competing to control the oligomerization of a common receptor.
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Affiliation(s)
- Charlotte H. Coles
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Yingjie Shen
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
| | - Alan P. Tenney
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
- Motor Neuron Center, Columbia University, New York, NY 10032, USA
| | - Christian Siebold
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Geoffrey C. Sutton
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Weixian Lu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - John T. Gallagher
- School of Cancer and Imaging Sciences, Faculty of Medical and Health Sciences, University of Manchester, Paterson Institute for Cancer Research, Manchester M20 4BX, UK
- Iduron, Paterson Institute for Cancer Research, University of Manchester, Manchester M20 4BX, UK
| | - E. Yvonne Jones
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - John G. Flanagan
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
| | - A. Radu Aricescu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
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40
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Britt JM, Kane JR, Spaeth CS, Zuzek A, Robinson GL, Gbanaglo MY, Estler CJ, Boydston EA, Schallert T, Bittner GD. Polyethylene glycol rapidly restores axonal integrity and improves the rate of motor behavior recovery after sciatic nerve crush injury. J Neurophysiol 2010; 104:695-703. [PMID: 20445038 DOI: 10.1152/jn.01051.2009] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The inability to rapidly (within minutes to hours) improve behavioral function after severance of peripheral nervous system axons is an ongoing clinical problem. We have previously reported that polyethylene glycol (PEG) can rapidly restore axonal integrity (PEG-fusion) between proximal and distal segments of cut- and crush-severed rat axons in vitro and in vivo. We now report that PEG-fusion not only reestablishes the integrity of crush-severed rat sciatic axons as measured by the restored conduction of compound action potentials (CAPs) and the intraaxonal diffusion of fluorescent dye across the lesion site, but also produces more rapid recovery of appropriate hindlimb motor behaviors. Improvement in recovery occurred during the first few postoperative weeks for the foot fault (FF) asymmetry test and between week 2 and week 3 for the Sciatic Functional Index (SFI) based on analysis of footprints. That is, the FF test was the more sensitive indicator of early behavioral recovery, showing significant postoperative improvement of motor behavior in PEG-treated animals at 24-48 h. In contrast, the SFI more sensitively measured longer-term postoperative behavioral recovery and deficits at 4-8 wk, perhaps reflecting the development of fine (distal) motor control. These and other data show that PEG-fusion not only rapidly restores physiological and morphological axonal continuity, but also more quickly improves behavioral recovery.
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Affiliation(s)
- Joshua M Britt
- Department of Psychology, University of Texas at Austin, Austin, Texas 78712, USA.
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41
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Kwon SK, Woo J, Kim SY, Kim H, Kim E. Trans-synaptic adhesions between netrin-G ligand-3 (NGL-3) and receptor tyrosine phosphatases LAR, protein-tyrosine phosphatase delta (PTPdelta), and PTPsigma via specific domains regulate excitatory synapse formation. J Biol Chem 2010; 285:13966-78. [PMID: 20139422 PMCID: PMC2859559 DOI: 10.1074/jbc.m109.061127] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2009] [Revised: 01/12/2010] [Indexed: 01/15/2023] Open
Abstract
Synaptic cell adhesion molecules regulate various steps of synapse formation. The trans-synaptic adhesion between postsynaptic NGL-3 (for netrin-G ligand-3) and presynaptic LAR (for leukocyte antigen-related) regulates excitatory synapse formation in a bidirectional manner. However, little is known about the molecular details of the NGL-3-LAR adhesion and whether two additional LAR family proteins, protein-tyrosine phosphatase delta (PTPdelta), and PTPsigma, also interact with NGL-3 and are involved in synapse formation. We report here that the leucine-rich repeat (LRR) domain of NGL-3, containing nine LRRs, interacts with the first two fibronectin III (FNIII) domains of LAR to induce bidirectional synapse formation. Moreover, Gln-96 in the first LRR motif of NGL-3 is critical for LAR binding and induction of presynaptic differentiation. PTPdelta and PTPsigma also interact with NGL-3 via their first two FNIII domains. These two interactions promote synapse formation in a different manner; the PTPsigma-NGL-3 interaction promotes synapse formation in a bidirectional manner, whereas the PTPdelta-NGL-3 interaction instructs only presynaptic differentiation in a unidirectional manner. mRNAs encoding LAR family proteins display overlapping and differential expression patterns in various brain regions. These results suggest that trans-synaptic adhesion between NGL-3 and the three LAR family proteins regulates excitatory synapse formation in shared and distinct neural circuits.
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Affiliation(s)
- Seok-Kyu Kwon
- From the National Creative Research Initiative Center for Synaptogenesis, Department of Biological Sciences, and Department of Nanoscience and Technology, Korea Advanced Institute of Science and Technology, Daejeon 305-701 and
| | - Jooyeon Woo
- From the National Creative Research Initiative Center for Synaptogenesis, Department of Biological Sciences, and Department of Nanoscience and Technology, Korea Advanced Institute of Science and Technology, Daejeon 305-701 and
| | - Soo-Young Kim
- the Department of Anatomy and Division of Brain Korea 21 Biomedical Science, College of Medicine, Korea University, 126-1, 5-Ka, Anam-Dong, Seongbuk-Gu, Seoul 136-705, Korea
| | - Hyun Kim
- the Department of Anatomy and Division of Brain Korea 21 Biomedical Science, College of Medicine, Korea University, 126-1, 5-Ka, Anam-Dong, Seongbuk-Gu, Seoul 136-705, Korea
| | - Eunjoon Kim
- From the National Creative Research Initiative Center for Synaptogenesis, Department of Biological Sciences, and Department of Nanoscience and Technology, Korea Advanced Institute of Science and Technology, Daejeon 305-701 and
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42
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Fry EJ, Chagnon MJ, López-Vales R, Tremblay ML, David S. Corticospinal tract regeneration after spinal cord injury in receptor protein tyrosine phosphatase sigma deficient mice. Glia 2010; 58:423-33. [PMID: 19780196 DOI: 10.1002/glia.20934] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Receptor protein tyrosine phosphatase sigma (RPTPsigma) plays a role in inhibiting axon growth during development. It has also been shown to slow axon regeneration after peripheral nerve injury and inhibit axon regeneration in the optic nerve. Here, we assessed the ability of the corticospinal tract (CST) axons to regenerate after spinal hemisection and contusion injury in RPTPsigma deficient (RPTPsigma(-/-)) mice. We show that damaged CST fibers in RPTPsigma(-/-) mice regenerate and appear to extend for long distances after a dorsal hemisection or contusion injury of the thoracic spinal cord. In contrast, no long distance axon regeneration of CST fibers is seen after similar lesions in wild-type mice. In vitro experiments indicate that cerebellar granule neurons from RPTPsigma(-/-) mice have reduced sensitivity to the inhibitory effects of chondroitin sulfate proteoglycan (CSPG) substrate, but not myelin, which may contribute to the growth of CST axons across the CSPG-rich glial scar. Our data suggest that RPTPsigma may function to prevent axonal growth after injury in the adult mammalian spinal cord and could be a target for promoting long distance regeneration after spinal cord injury.
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Affiliation(s)
- Elizabeth J Fry
- Centre for Research in Neuroscience, The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
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43
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Duan Y, Giger RJ. A new role for RPTPsigma in spinal cord injury: signaling chondroitin sulfate proteoglycan inhibition. Sci Signal 2010; 3:pe6. [PMID: 20179269 DOI: 10.1126/scisignal.3110pe6] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
It has been known for more than two decades that chondroitin sulfate proteoglycans (CSPGs) inhibit axonal growth and regeneration. In the adult nervous system, CSPGs are enriched in perineuronal nets, and their abundance is increased in reactive astrocytes following injury to brain or spinal cord. Degradation of chondroitin sulfate (CS) sugar moieties by the local infusion of the bacterial enzyme chondroitinase ABC (ChaseABC) enhances experience-dependent neuronal plasticity in the adult visual cortex and results in substantially improved behavioral outcomes after spinal cord injury (SCI). Although the positive effects of ChaseABC treatment on neuronal plasticity have been known for some time, the underlying mechanisms remained enigmatic. The receptor protein tyrosine phosphatase sigma (RPTPsigma) has now been identified as a receptor for inhibitory CSPGs. Similarly to ChaseABC treatment, functional ablation of Ptprs, the gene encoding RPTPsigma, promotes neurite outgrowth in the presence of CSPGs in vitro and enhances axonal growth into CSPG-rich scar tissue following SCI in vivo. The discovery of neuronal RPTPsigma as a receptor for inhibitory CSPGs not only provides important mechanistic clues about CSPG function, but also identifies a potential new target for enhancing axonal growth and plasticity after nervous system injury.
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Affiliation(s)
- Yuntao Duan
- Department of Cell and Developmental Biology and Department of Neurology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
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44
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Shen Y, Tenney AP, Busch SA, Horn KP, Cuascut FX, Liu K, He Z, Silver J, Flanagan JG. PTPsigma is a receptor for chondroitin sulfate proteoglycan, an inhibitor of neural regeneration. Science 2009; 326:592-6. [PMID: 19833921 PMCID: PMC2811318 DOI: 10.1126/science.1178310] [Citation(s) in RCA: 498] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Chondroitin sulfate proteoglycans (CSPGs) present a barrier to axon regeneration. However, no specific receptor for the inhibitory effect of CSPGs has been identified. We showed that a transmembrane protein tyrosine phosphatase, PTPsigma, binds with high affinity to neural CSPGs. Binding involves the chondroitin sulfate chains and a specific site on the first immunoglobulin-like domain of PTPsigma. In culture, PTPsigma(-/-) neurons show reduced inhibition by CSPG. A PTPsigma fusion protein probe can detect cognate ligands that are up-regulated specifically at neural lesion sites. After spinal cord injury, PTPsigma gene disruption enhanced the ability of axons to penetrate regions containing CSPG. These results indicate that PTPsigma can act as a receptor for CSPGs and may provide new therapeutic approaches to neural regeneration.
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Affiliation(s)
- Yingjie Shen
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
| | - Alan P. Tenney
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
| | - Sarah A. Busch
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Kevin P. Horn
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Fernando X. Cuascut
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Kai Liu
- Division of Neuroscience, Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Zhigang He
- Division of Neuroscience, Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jerry Silver
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - John G. Flanagan
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
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Sakakima H, Yoshida Y, Yamazaki Y, Matsuda F, Ikutomo M, Ijiri K, Muramatsu H, Muramatsu T, Kadomatsu K. Disruption of the midkine gene (Mdk) delays degeneration and regeneration in injured peripheral nerve. J Neurosci Res 2009; 87:2908-15. [DOI: 10.1002/jnr.22127] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Abstract
For more than three decades, the venom of the black widow spider and its principal active components, latrotoxins, have been used to induce release of neurotransmitters and hormones and to study the mechanisms of exocytosis. Given the complex nature of alpha--latrotoxin (alpha-LTX) actions, this research has been continuously overshadowed by many enigmas, misconceptions and perpetual changes of the underlying hypotheses. Some of the toxin's mechanisms of action are still not completely understood. Despite all these difficulties, the extensive work of several generations of neurobiologists has brought about a great deal of fascinating insights into pre-synaptic processes and has led to the discovery of several novel proteins and synaptic systems. For example, alpha-LTX studies have contributed to the widespread acceptance of the vesicular theory of transmitter release. Pre-synaptic receptors for alpha-LTX--neurexins, latrophilins and protein tyrosine phosphatase sigma--and their endogenous ligands have now become centrepieces of their own areas of research, with a potential of uncovering new mechanisms of synapse formation and regulation that may have medical implications. However, any future success of alpha-LTX research will require a better understanding of this unusual natural tool and a more precise dissection of its multiple mechanisms.
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Affiliation(s)
- John-Paul Silva
- Division of Cell and Molecular Biology, Imperial College London, Exhibition Road, London, UK
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Elfar JC, Jacobson JA, Puzas JE, Rosier RN, Zuscik MJ. Erythropoietin accelerates functional recovery after peripheral nerve injury. J Bone Joint Surg Am 2008; 90:1644-53. [PMID: 18676893 PMCID: PMC4470043 DOI: 10.2106/jbjs.g.00557] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND Erythropoietin is a naturally occurring hormone with multiple effects on a number of different cell types. Recent data have suggested neuroprotective and perhaps even neurotrophic roles for erythropoietin. We hypothesized that these functional effects could be demonstrable in standard models of peripheral nerve injury. METHODS Experiments were undertaken to evaluate the effect of erythropoietin on the previously reported standard course of healing of sciatic injuries in mice. The injury groups included mice that were subjected to (1) sham surgery, (2) a calibrated sciatic crush injury, (3) transection of the sciatic nerve followed by epineural repair, or (4) a transection followed by burial of the proximal stump in the adjacent muscle tissue (neurectomy). Either erythropoietin or saline solution was administered to the mice in each of these experimental groups twenty-four hours preinjury, immediately after surgical creation of the injury, twenty-four hours postinjury, or one week postinjury. All mice were evaluated on the basis of the published model for recovery of sciatic nerve motor function by measuring footprint parameters at specific times after the injury. Immunohistochemistry was also performed to assess the erythropoietin-receptor expression profile at the site of injury. RESULTS In general, the mice treated with erythropoietin recovered sciatic nerve motor function significantly faster than did the untreated controls. This conclusion was based on a sciatic function index that was 60% better in the erythropoietin-treated mice at seven days postinjury (p < 0.05). Although the group that had been given the erythropoietin immediately postinjury showed the best enhancement of recovery, the timing of the administration of the drug was not critical. Histological analysis demonstrated enhanced erythropoietin-receptor positivity in the nerves that recovered fastest, suggesting that accelerated healing correlates with expression of the receptor in nerve tissue. CONCLUSIONS Erythropoietin treatment of an acute sciatic nerve crush injury leads to an effect consistent with functional neuroprotection. This protective effect may have clinical relevance, especially since it was detectable even when erythropoietin had been administered up to one week after injury.
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Affiliation(s)
- John C. Elfar
- Department of Orthopaedics and Rehabilitation, University
of Rochester, 601 Elmwood Avenue, Rochester, NY 14620. E-mail address for J.A.
Jacobson:
| | - Justin A. Jacobson
- Department of Orthopaedics and Rehabilitation, University
of Rochester, 601 Elmwood Avenue, Rochester, NY 14620. E-mail address for J.A.
Jacobson:
| | - J. Edward Puzas
- Department of Orthopaedics and Rehabilitation, University
of Rochester, 601 Elmwood Avenue, Rochester, NY 14620. E-mail address for J.A.
Jacobson:
| | - Randy N. Rosier
- Department of Orthopaedics and Rehabilitation, University
of Rochester, 601 Elmwood Avenue, Rochester, NY 14620. E-mail address for J.A.
Jacobson:
| | - Michael J. Zuscik
- Department of Orthopaedics and Rehabilitation, University
of Rochester, 601 Elmwood Avenue, Rochester, NY 14620. E-mail address for J.A.
Jacobson:
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Hendriks WJAJ, Elson A, Harroch S, Stoker AW. Protein tyrosine phosphatases: functional inferences from mouse models and human diseases. FEBS J 2008; 275:816-30. [DOI: 10.1111/j.1742-4658.2008.06249.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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49
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Abstract
alpha-Latrotoxin (alpha-LTX) from black widow spider venom induces exhaustive release of neurotransmitters from vertebrate nerve terminals and endocrine cells. This 130-kDa protein has been employed for many years as a molecular tool to study exocytosis. However, its action is complex: in neurons, alpha-LTX induces massive secretion both in the presence of extracellular Ca(2+) (Ca(2+) (e)) and in its absence; in endocrine cells, it usually requires Ca(2+) (e). To use this toxin for further dissection of secretory mechanisms, one needs an in-depth understanding of its functions. One such function that explains some alpha-LTX effects is its ability to form cation-permeable channels in artificial lipid bilayers. The mechanism of alpha-LTX pore formation, revealed by cryo-electron microscopy, involves toxin assembly into homotetrameric complexes which harbor a central channel and can insert into lipid membranes. However, in biological membranes, alpha-LTX cannot exert its actions without binding to specific receptors of the plasma membrane. Three proteins with distinct structures have been found to bind alpha-LTX: neurexin Ialpha, latrophilin 1, and receptor-like protein tyrosine phosphatase sigma. Upon binding a receptor, alpha-LTX forms channels permeable to cations and small molecules; the toxin may also activate the receptor. To distinguish between the pore- and receptor-mediated effects, and to study structure-function relationships in the toxin, alpha-LTX mutants have been used.
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Affiliation(s)
- Yuri A Ushkaryov
- Division of Cell and Molecular Biology, Imperial College London, London, SW7 2AY, UK.
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50
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Faux C, Hawadle M, Nixon J, Wallace A, Lee S, Murray S, Stoker A. PTPσ binds and dephosphorylates neurotrophin receptors and can suppress NGF-dependent neurite outgrowth from sensory neurons. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:1689-700. [DOI: 10.1016/j.bbamcr.2007.06.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Revised: 06/22/2007] [Accepted: 06/25/2007] [Indexed: 12/25/2022]
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