101
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Pardo L, Schlüter A, Valor LM, Barco A, Giralt M, Golbano A, Hidalgo J, Jia P, Zhao Z, Jové M, Portero-Otin M, Ruiz M, Giménez-Llort L, Masgrau R, Pujol A, Galea E. Targeted activation of CREB in reactive astrocytes is neuroprotective in focal acute cortical injury. Glia 2016; 64:853-74. [PMID: 26880229 DOI: 10.1002/glia.22969] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 01/07/2016] [Accepted: 01/08/2016] [Indexed: 01/07/2023]
Abstract
The clinical challenge in acute injury as in traumatic brain injury (TBI) is to halt the delayed neuronal loss that occurs hours and days after the insult. Here we report that the activation of CREB-dependent transcription in reactive astrocytes prevents secondary injury in cerebral cortex after experimental TBI. The study was performed in a novel bitransgenic mouse in which a constitutively active CREB, VP16-CREB, was targeted to astrocytes with the Tet-Off system. Using histochemistry, qPCR, and gene profiling we found less neuronal death and damage, reduced macrophage infiltration, preserved mitochondria, and rescued expression of genes related to mitochondrial metabolism in bitransgenic mice as compared to wild type littermates. Finally, with meta-analyses using publicly available databases we identified a core set of VP16-CREB candidate target genes that may account for the neuroprotective effect. Enhancing CREB activity in astrocytes thus emerges as a novel avenue in acute brain post-injury therapeutics.
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Affiliation(s)
- Luis Pardo
- Institut De Neurociències and Unitat De Bioquímica, Facultat De Medicina, Universitat Autònoma De Barcelona, Bellaterra, Barcelona, 08193, Spain
| | - Agatha Schlüter
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), Center for Biomedical Research on Rare Diseases (CIBERER), ISCIII, L'hospitalet De Llobregat, Barcelona, 08907, Spain
| | - Luis M Valor
- Instituto De Neurociencias De Alicante, Universidad Miguel Hernández/Consejo Superior De Investigaciones Científicas, Sant Joan D'alacant, Alicante, 03550, Spain
| | - Angel Barco
- Instituto De Neurociencias De Alicante, Universidad Miguel Hernández/Consejo Superior De Investigaciones Científicas, Sant Joan D'alacant, Alicante, 03550, Spain
| | - Mercedes Giralt
- Institut De Neurociències and Department of Cellular Biology, Physiology and Immunology, Faculty of Biosciences, Universitat Autònoma, Barcelona, 08193, Spain
| | - Arantxa Golbano
- Institut De Neurociències and Unitat De Bioquímica, Facultat De Medicina, Universitat Autònoma De Barcelona, Bellaterra, Barcelona, 08193, Spain
| | - Juan Hidalgo
- Institut De Neurociències and Department of Cellular Biology, Physiology and Immunology, Faculty of Biosciences, Universitat Autònoma, Barcelona, 08193, Spain
| | - Peilin Jia
- Department of Biomedical Informatics, Vanderbilt University School of Medicine, Nashville, Tennessee.,Department of Psychiatry, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Zhongming Zhao
- Department of Biomedical Informatics, Vanderbilt University School of Medicine, Nashville, Tennessee.,Department of Psychiatry, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Mariona Jové
- Department of Experimental Medicine, University of Lleida-Biomedical Research Institute of Lleida, Lleida, 25198, Spain
| | - Manuel Portero-Otin
- Department of Experimental Medicine, University of Lleida-Biomedical Research Institute of Lleida, Lleida, 25198, Spain
| | - Montserrat Ruiz
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), Center for Biomedical Research on Rare Diseases (CIBERER), ISCIII, L'hospitalet De Llobregat, Barcelona, 08907, Spain
| | - Lydia Giménez-Llort
- Institut De Neurociènces and Department of Psychiatry and Forensic Medicine, School of Medicine, Universitat Autònoma De Barcelona, Bellaterra, 08193, Spain
| | - Roser Masgrau
- Institut De Neurociències and Unitat De Bioquímica, Facultat De Medicina, Universitat Autònoma De Barcelona, Bellaterra, Barcelona, 08193, Spain
| | - Aurora Pujol
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), Center for Biomedical Research on Rare Diseases (CIBERER), ISCIII, L'hospitalet De Llobregat, Barcelona, 08907, Spain.,Institució Catalana De Recerca I Estudis Avançats (ICREA), Barcelona, Spain
| | - Elena Galea
- Institut De Neurociències and Unitat De Bioquímica, Facultat De Medicina, Universitat Autònoma De Barcelona, Bellaterra, Barcelona, 08193, Spain.,Institució Catalana De Recerca I Estudis Avançats (ICREA), Barcelona, Spain
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102
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Sustained Arginase 1 Expression Modulates Pathological Tau Deposits in a Mouse Model of Tauopathy. J Neurosci 2016; 35:14842-60. [PMID: 26538654 DOI: 10.1523/jneurosci.3959-14.2015] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Tau accumulation remains one of the closest correlates of neuronal loss in Alzheimer's disease. In addition, tau associates with several other neurodegenerative diseases, collectively known as tauopathies, in which clinical phenotypes manifest as cognitive impairment, behavioral disturbances, and motor impairment. Polyamines act as bivalent regulators of cellular function and are involved in numerous biological processes. The regulation of the polyamines system can become dysfunctional during disease states. Arginase 1 (Arg1) and nitric oxide synthases compete for l-arginine to produce either polyamines or nitric oxide, respectively. Herein, we show that overexpression of Arg1 using adeno-associated virus (AAV) in the CNS of rTg4510 tau transgenic mice significantly reduced phospho-tau species and tangle pathology. Sustained Arg1 overexpression decreased several kinases capable of phosphorylating tau, decreased inflammation, and modulated changes in the mammalian target of rapamycin and related proteins, suggesting activation of autophagy. Arg1 overexpression also mitigated hippocampal atrophy in tau transgenic mice. Conversely, conditional deletion of Arg1 in myeloid cells resulted in increased tau accumulation relative to Arg1-sufficient mice after transduction with a recombinant AAV-tau construct. These data suggest that Arg1 and the polyamine pathway may offer novel therapeutic targets for tauopathies.
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103
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Abstract
UNLABELLED Understanding why adult CNS neurons fail to regenerate their axons following injury remains a central challenge of neuroscience research. A more complete appreciation of the biological mechanisms shaping the injured nervous system is a crucial prerequisite for the development of robust therapies to promote neural repair. Historically, the identification of regeneration associated signaling pathways has been impeded by the limitations of available genetic and molecular tools. As we progress into an era in which the high-throughput interrogation of gene expression is commonplace and our knowledge base of interactome data is rapidly expanding, we can now begin to assemble a more comprehensive view of the complex biology governing axon regeneration. Here, we highlight current and ongoing work featuring transcriptomic approaches toward the discovery of novel molecular mechanisms that can be manipulated to promote neural repair. SIGNIFICANCE STATEMENT Transcriptional profiling is a powerful technique with broad applications in the field of neuroscience. Recent advances such as single-cell transcriptomics, CNS cell type-specific and developmental stage-specific expression libraries are rapidly enhancing the power of transcriptomics for neuroscience applications. However, extracting biologically meaningful information from large transcriptomic datasets remains a formidable challenge. This mini-symposium will highlight current work using transcriptomic approaches to identify regulatory networks in the injured nervous system. We will discuss analytical strategies for transcriptomics data, the significance of noncoding RNA networks, and the utility of multiomic data integration. Though the studies featured here specifically focus on neural repair, the approaches highlighted in this mini-symposium will be of broad interest and utility to neuroscientists working in diverse areas of the field.
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104
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Goganau I, Blesch A. Gene Therapy for Spinal Cord Injury. Transl Neurosci 2016. [DOI: 10.1007/978-1-4899-7654-3_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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105
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Intrinsic Neuronal Mechanisms in Axon Regeneration After Spinal Cord Injury. Transl Neurosci 2016. [DOI: 10.1007/978-1-4899-7654-3_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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106
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van Niekerk EA, Tuszynski MH, Lu P, Dulin JN. Molecular and Cellular Mechanisms of Axonal Regeneration After Spinal Cord Injury. Mol Cell Proteomics 2015; 15:394-408. [PMID: 26695766 DOI: 10.1074/mcp.r115.053751] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Indexed: 12/28/2022] Open
Abstract
Following axotomy, a complex temporal and spatial coordination of molecular events enables regeneration of the peripheral nerve. In contrast, multiple intrinsic and extrinsic factors contribute to the general failure of axonal regeneration in the central nervous system. In this review, we examine the current understanding of differences in protein expression and post-translational modifications, activation of signaling networks, and environmental cues that may underlie the divergent regenerative capacity of central and peripheral axons. We also highlight key experimental strategies to enhance axonal regeneration via modulation of intraneuronal signaling networks and the extracellular milieu. Finally, we explore potential applications of proteomics to fill gaps in the current understanding of molecular mechanisms underlying regeneration, and to provide insight into the development of more effective approaches to promote axonal regeneration following injury to the nervous system.
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Affiliation(s)
- Erna A van Niekerk
- From the ‡Department of Neurosciences, University of California, San Diego, La Jolla, CA, 92093;
| | - Mark H Tuszynski
- From the ‡Department of Neurosciences, University of California, San Diego, La Jolla, CA, 92093; §Veterans Administration Medical Center, San Diego, CA 92161
| | - Paul Lu
- From the ‡Department of Neurosciences, University of California, San Diego, La Jolla, CA, 92093; §Veterans Administration Medical Center, San Diego, CA 92161
| | - Jennifer N Dulin
- From the ‡Department of Neurosciences, University of California, San Diego, La Jolla, CA, 92093
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107
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Acute Putrescine Supplementation with Schwann Cell Implantation Improves Sensory and Serotonergic Axon Growth and Functional Recovery in Spinal Cord Injured Rats. Neural Plast 2015; 2015:186385. [PMID: 26550496 PMCID: PMC4621347 DOI: 10.1155/2015/186385] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 06/25/2015] [Accepted: 07/02/2015] [Indexed: 01/29/2023] Open
Abstract
Schwann cell (SC) transplantation exhibits significant potential for spinal cord injury (SCI) repair and its use as a therapeutic modality has now progressed to clinical trials for subacute and chronic human SCI. Although SC implants provide a receptive environment for axonal regrowth and support functional recovery in a number of experimental SCI models, axonal regeneration is largely limited to local systems and the behavioral improvements are modest without additional combinatory approaches. In the current study we investigated whether the concurrent delivery of the polyamine putrescine, started either 30 min or 1 week after SCI, could enhance the efficacy of SCs when implanted subacutely (1 week after injury) into the contused rat spinal cord. Polyamines are ubiquitous organic cations that play an important role in the regulation of the cell cycle, cell division, cytoskeletal organization, and cell differentiation. We show that the combination of putrescine with SCs provides a significant increase in implant size, an enhancement in axonal (sensory and serotonergic) sparing and/or growth, and improved open field locomotion after SCI, as compared to SC implantation alone. These findings demonstrate that polyamine supplementation can augment the effectiveness of SCs when used as a therapeutic approach for subacute SCI repair.
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108
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Fagoe ND, Attwell CL, Kouwenhoven D, Verhaagen J, Mason MRJ. Overexpression of ATF3 or the combination of ATF3, c-Jun, STAT3 and Smad1 promotes regeneration of the central axon branch of sensory neurons but without synergistic effects. Hum Mol Genet 2015; 24:6788-800. [PMID: 26385639 DOI: 10.1093/hmg/ddv383] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 09/11/2015] [Indexed: 12/26/2022] Open
Abstract
Peripheral nerve injury results in the activation of a number of transcription factors (TFs) in injured neurons, some of which may be key regulators of the regeneration-associated gene (RAG) programme. Among known RAG TFs, ATF3, Smad1, STAT3 and c-Jun have all been linked to successful axonal regeneration and have known functional and physical interactions. We hypothesised that TF expression would promote regeneration of the central axon branch of DRG neurons in the absence of a peripheral nerve lesion and that simultaneous overexpression of multiple RAG TFs would lead to greater effects than delivery of a single TF. Using adeno-associated viral vectors, we overexpressed either the combination of ATF3, Smad1, STAT3 and c-Jun with farnesylated GFP (fGFP), ATF3 only with fGFP, or fGFP only, in DRG neurons and assessed axonal regeneration after dorsal root transection or dorsal column injury and functional improvement after dorsal root injury. ATF3 alone and the combination of TFs promoted faster regeneration in the injured dorsal root. Surprisingly, however, the combination did not perform better than ATF3 alone. Neither treatment was able to induce functional improvement on sensory tests after dorsal root injury or promote regeneration in a dorsal column injury model. The lack of synergistic effects among these factors indicates that while they do increase the speed of axon growth, there may be functional redundancy between these TFs. Because axon growth is considerably less than that seen after a conditioning lesion, it appears these TFs do not induce the full regeneration programme.
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Affiliation(s)
- Nitish D Fagoe
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, an Institute of the Royal Academy of Arts and Sciences, Meibergdreef 47, Amsterdam 1105BA, The Netherlands and
| | - Callan L Attwell
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, an Institute of the Royal Academy of Arts and Sciences, Meibergdreef 47, Amsterdam 1105BA, The Netherlands and
| | - Dorette Kouwenhoven
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, an Institute of the Royal Academy of Arts and Sciences, Meibergdreef 47, Amsterdam 1105BA, The Netherlands and
| | - Joost Verhaagen
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, an Institute of the Royal Academy of Arts and Sciences, Meibergdreef 47, Amsterdam 1105BA, The Netherlands and Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, De Boelelaan 1085, Amsterdam 1081HV, The Netherlands
| | - Matthew R J Mason
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, an Institute of the Royal Academy of Arts and Sciences, Meibergdreef 47, Amsterdam 1105BA, The Netherlands and
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109
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Wang T, Yuan W, Liu Y, Zhang Y, Wang Z, Chen X, Feng S, Xiu Y, Li W. miR-142-3p is a Potential Therapeutic Target for Sensory Function Recovery of Spinal Cord Injury. Med Sci Monit 2015; 21:2553-6. [PMID: 26318123 PMCID: PMC4557393 DOI: 10.12659/msm.894098] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Spinal cord injury (SCI), which is a leading cause of disability in modern society, commonly results from trauma. It has been reported that application of sciatic nerve conditioning injury plays a positive role in repairing the injury of the ascending spinal sensory pathway in laboratory animals. Because of the complexity of SCI and related ethics challenges, sciatic nerve conditioning injury cannot be applied in clinical therapy. Accordingly, it is extremely important to study its mechanism and develop replacement therapy. Based on empirical study and clinical trials, this article suggests that miR-142-3p is the key therapeutic target for repairing sensory function, based on the following evidence. Firstly, studies have reported that endogenous cAMP is the upstream regulator of 3 signal pathways that are partially involved in the mechanisms of sciatic nerve conditioning injury, promoting neurite growth. The regulated miR-142-3p can induce cAMP elevation via adenylyl cyclase 9 (AC9), which is abundant in dorsal root ganglia (DRG). Secondly, compared with gene expression regulation in the injured spinal cord, inhibition of microRNA (miRNA) in DRG is less likely to cause trauma and infection. Thirdly, evidence of miRNAs as biomarkers and therapeutic targets in many diseases has been reported. In this article we suggest, for the first time, imitating sciatic nerve conditioning injury, thereby enhancing central regeneration of primary sensory neurons via interfering with the congenerous upstream regulator AC9 of the 3 above-mentioned signal pathways. We hope to provide a new clinical treatment strategy for the recovery of sensory function in SCI patients.
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Affiliation(s)
- Tianyi Wang
- Department of Orthopedics, Tianjin Medical University General Hospital, Tianjin, China (mainland)
| | - Wenqi Yuan
- Department of Orthopedics, Tianjin Medical University General Hospital, Tianjin, China (mainland)
| | - Yong Liu
- Department of Orthopedics, Tianjin Medical University General Hospital, Tianjin, China (mainland)
| | - Yanjun Zhang
- Department of Orthopedics, Tianjin Medical University General Hospital, Tianjin, China (mainland)
| | - Zhijie Wang
- Department of Pediatric Internal Medicine, Affiliated Hospital of Chengde Medical College, Chengde, Hebei, China (mainland)
| | - Xueming Chen
- Department of Orthopedics, Tianjin Medical University General Hospital, Tianjin, China (mainland)
| | - Shiqing Feng
- Department of Orthopedics, Tianjin Medical University General Hospital, Tianjin, China (mainland)
| | - Yucai Xiu
- Department of Orthopedics, The 266th Hospital of the Chinese People's Liberation Army, Chengde, Hebei, China (mainland)
| | - Wenhua Li
- Department of Orthopedics, The 266th Hospital of the Chinese People's Liberation Army, Chengde, Hebei, China (mainland)
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110
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Inhibitory Injury Signaling Represses Axon Regeneration After Dorsal Root Injury. Mol Neurobiol 2015; 53:4596-605. [PMID: 26298667 DOI: 10.1007/s12035-015-9397-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 08/14/2015] [Indexed: 01/05/2023]
Abstract
Following injury to peripheral axons, besides increased cyclic adenosine monophosphate (cAMP), the positive injury signals extracellular-signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and signal transducer and activator of transcription 3 (STAT-3) are locally activated and retrogradely transported to the cell body, where they induce a pro-regenerative program. Here, to further understand the importance of injury signaling for successful axon regeneration, we used dorsal root ganglia (DRG) neurons that have a central branch without regenerative capacity and a peripheral branch that regrows after lesion. Although injury to the DRG central branch (dorsal root injury (DRI)) activated ERK, JNK, and STAT-3 and increased cAMP levels, it did not elicit gain of intrinsic growth capacity nor the ability to overcome myelin inhibition, as occurred after peripheral branch injury (sciatic nerve injury (SNI)). Besides, gain of growth capacity after SNI was independent of ERK and cAMP. Antibody microarrays of dynein-immunoprecipitated axoplasm from rats with either DRI or SNI revealed a broad differential activation and transport of signals after each injury type and further supported that ERK, JNK, STAT-3, and cAMP signaling pathways are minor contributors to the differential intrinsic axon growth capacity of both injury models. Increased levels of inhibitory injury signals including GSK3β and ROCKII were identified after DRI, not only in axons but also in DRG cell bodies. In summary, our work shows that activation and transport of positive injury signals are not sufficient to promote increased axon growth capacity and that differential modulation of inhibitory molecules may contribute to limited regenerative response.
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111
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Simpson MT, Venkatesh I, Callif BL, Thiel LK, Coley DM, Winsor KN, Wang Z, Kramer AA, Lerch JK, Blackmore MG. The tumor suppressor HHEX inhibits axon growth when prematurely expressed in developing central nervous system neurons. Mol Cell Neurosci 2015; 68:272-83. [PMID: 26306672 DOI: 10.1016/j.mcn.2015.08.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 07/30/2015] [Accepted: 08/17/2015] [Indexed: 01/21/2023] Open
Abstract
Neurons in the embryonic and peripheral nervous system respond to injury by activating transcriptional programs supportive of axon growth, ultimately resulting in functional recovery. In contrast, neurons in the adult central nervous system (CNS) possess a limited capacity to regenerate axons after injury, fundamentally constraining repair. Activating pro-regenerative gene expression in CNS neurons is a promising therapeutic approach, but progress is hampered by incomplete knowledge of the relevant transcription factors. An emerging hypothesis is that factors implicated in cellular growth and motility outside the nervous system may also control axon growth in neurons. We therefore tested sixty-nine transcription factors, previously identified as possessing tumor suppressive or oncogenic properties in non-neuronal cells, in assays of neurite outgrowth. This screen identified YAP1 and E2F1 as enhancers of neurite outgrowth, and PITX1, RBM14, ZBTB16, and HHEX as inhibitors. Follow-up experiments are focused on the tumor suppressor HHEX, one of the strongest growth inhibitors. HHEX is widely expressed in adult CNS neurons, including corticospinal tract neurons after spinal injury, but is present only in trace amounts in immature cortical neurons and adult peripheral neurons. HHEX overexpression in early postnatal cortical neurons reduced both initial axonogenesis and the rate of axon elongation, and domain deletion analysis strongly implicated transcriptional repression as the underlying mechanism. These findings suggest a role for HHEX in restricting axon growth in the developing CNS, and substantiate the hypothesis that previously identified oncogenes and tumor suppressors can play conserved roles in axon extension.
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Affiliation(s)
- Matthew T Simpson
- Marquette University, Department of Biomedical Sciences, 53201, United States
| | - Ishwariya Venkatesh
- Marquette University, Department of Biomedical Sciences, 53201, United States
| | - Ben L Callif
- Marquette University, Department of Biomedical Sciences, 53201, United States
| | - Laura K Thiel
- Marquette University, Department of Biomedical Sciences, 53201, United States
| | - Denise M Coley
- Marquette University, Department of Biomedical Sciences, 53201, United States
| | - Kristen N Winsor
- Marquette University, Department of Biomedical Sciences, 53201, United States
| | - Zimei Wang
- Marquette University, Department of Biomedical Sciences, 53201, United States
| | - Audra A Kramer
- Marquette University, Department of Biomedical Sciences, 53201, United States
| | - Jessica K Lerch
- The Ohio State University, The Center for Brain and Spinal Cord Repair, The Department of Neuroscience, 43210, United States
| | - Murray G Blackmore
- Marquette University, Department of Biomedical Sciences, 53201, United States.
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112
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Ma TC, Willis DE. What makes a RAG regeneration associated? Front Mol Neurosci 2015; 8:43. [PMID: 26300725 PMCID: PMC4528284 DOI: 10.3389/fnmol.2015.00043] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 07/24/2015] [Indexed: 12/31/2022] Open
Abstract
Regenerative failure remains a significant barrier for functional recovery after central nervous system (CNS) injury. As such, understanding the physiological processes that regulate axon regeneration is a central focus of regenerative medicine. Studying the gene transcription responses to axon injury of regeneration competent neurons, such as those of the peripheral nervous system (PNS), has provided insight into the genes associated with regeneration. Though several individual “regeneration-associated genes” (RAGs) have been identified from these studies, the response to injury likely regulates the expression of functionally coordinated and complementary gene groups. For instance, successful regeneration would require the induction of genes that drive the intrinsic growth capacity of neurons, while simultaneously downregulating the genes that convey environmental inhibitory cues. Thus, this view emphasizes the transcriptional regulation of gene “programs” that contribute to the overall goal of axonal regeneration. Here, we review the known RAGs, focusing on how their transcriptional regulation can reveal the underlying gene programs that drive a regenerative phenotype. Finally, we will discuss paradigms under which we can determine whether these genes are injury-associated, or indeed necessary for regeneration.
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Affiliation(s)
- Thong C Ma
- Department of Neurology, Columbia University New York, NY, USA
| | - Dianna E Willis
- Brain Mind Research Institute, Weill Cornell Medical College New York, NY, USA ; Burke-Cornell Medical Research Institute White Plains, NY, USA
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113
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Diekmann H, Kalbhen P, Fischer D. Active mechanistic target of rapamycin plays an ancillary rather than essential role in zebrafish CNS axon regeneration. Front Cell Neurosci 2015. [PMID: 26217179 PMCID: PMC4493654 DOI: 10.3389/fncel.2015.00251] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The developmental decrease of the intrinsic regenerative ability of the mammalian central nervous system (CNS) is associated with reduced activity of mechanistic target of rapamycin (mTOR) in mature neurons such as retinal ganglion cells (RGCs). While mTOR activity is further decreased upon axonal injury, maintenance of its pre-injury level, for instance by genetic deletion of the phosphatase and tensin homolog (PTEN), markedly promotes axon regeneration in mammals. The current study now addressed the question whether active mTOR might generally play a central role in axon regeneration by analyzing its requirement in regeneration-competent zebrafish. Remarkably, regulation of mTOR activity after optic nerve injury in zebrafish is fundamentally different compared to mammals. Hardly any activity was detected in naïve RGCs, whereas it was markedly increased upon axotomy in vivo as well as in dissociated cell cultures. After a short burst, mTOR activity was quickly attenuated, which is contrary to the requirements for axon regeneration in mammals. Surprisingly, mTOR activity was not essential for axonal growth per se, but correlated with cytokine- and PTEN inhibitor-induced neurite extension in vitro. Moreover, inhibition of mTOR using rapamycin significantly reduced axon regeneration in vivo and compromised functional recovery after optic nerve injury. Therefore, axotomy-induced mTOR activity is involved in CNS axon regeneration in zebrafish similar to mammals, although it plays an ancillary rather than essential role in this regeneration-competent species.
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Affiliation(s)
- Heike Diekmann
- Division of Experimental Neurology, Department of Neurology, Heinrich-Heine-University of Düsseldorf Düsseldorf, Germany
| | - Pascal Kalbhen
- Division of Experimental Neurology, Department of Neurology, Heinrich-Heine-University of Düsseldorf Düsseldorf, Germany
| | - Dietmar Fischer
- Division of Experimental Neurology, Department of Neurology, Heinrich-Heine-University of Düsseldorf Düsseldorf, Germany
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114
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Siddiq MM, Hannila SS. Looking downstream: the role of cyclic AMP-regulated genes in axonal regeneration. Front Mol Neurosci 2015; 8:26. [PMID: 26150769 PMCID: PMC4471816 DOI: 10.3389/fnmol.2015.00026] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 06/03/2015] [Indexed: 11/16/2022] Open
Abstract
Elevation of intracellular cyclic AMP (cAMP) levels has proven to be one of the most effective means of overcoming inhibition of axonal regeneration by myelin-associated inhibitors such as myelin-associated glycoprotein (MAG), Nogo, and oligodendrocyte myelin glycoprotein. Pharmacological manipulation of cAMP through the administration of dibutyryl cAMP or rolipram leads to enhanced axonal growth both in vivo and in vitro, and importantly, upregulation of cAMP within dorsal root ganglion neurons is responsible for the conditioning lesion effect, which indicates that cAMP plays a significant role in the endogenous mechanisms that promote axonal regeneration. The effects of cAMP are transcription-dependent and are mediated through the activation of protein kinase A (PKA) and the transcription factor cyclic AMP response element binding protein (CREB). This leads to the induction of a variety of genes, several of which have been shown to overcome myelin-mediated inhibition in their own right. In this review, we will highlight the pro-regenerative effects of arginase I (ArgI), interleukin (IL)-6, secretory leukocyte protease inhibitor (SLPI), and metallothionein (MT)-I/II, and discuss their potential for therapeutic use in spinal cord injury.
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Affiliation(s)
- Mustafa M Siddiq
- Icahn Medical Institute, Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine New York, NY, USA
| | - Sari S Hannila
- Department of Human Anatomy and Cell Science, University of Manitoba Winnipeg, MB, Canada
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115
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Baldwin KT, Giger RJ. Insights into the physiological role of CNS regeneration inhibitors. Front Mol Neurosci 2015; 8:23. [PMID: 26113809 PMCID: PMC4462676 DOI: 10.3389/fnmol.2015.00023] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 05/26/2015] [Indexed: 12/14/2022] Open
Abstract
The growth inhibitory nature of injured adult mammalian central nervous system (CNS) tissue constitutes a major barrier to robust axonal outgrowth and functional recovery following trauma or disease. Prototypic CNS regeneration inhibitors are broadly expressed in the healthy and injured brain and spinal cord and include myelin-associated glycoprotein (MAG), the reticulon family member NogoA, oligodendrocyte myelin glycoprotein (OMgp), and chondroitin sulfate proteoglycans (CSPGs). These structurally diverse molecules strongly inhibit neurite outgrowth in vitro, and have been most extensively studied in the context of nervous system injury in vivo. The physiological role of CNS regeneration inhibitors in the naïve, or uninjured, CNS remains less well understood, but has received growing attention in recent years and is the focus of this review. CNS regeneration inhibitors regulate myelin development and axon stability, consolidate neuronal structure shaped by experience, and limit activity-dependent modification of synaptic strength. Altered function of CNS regeneration inhibitors is associated with neuropsychiatric disorders, suggesting crucial roles in brain development and health.
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Affiliation(s)
- Katherine T Baldwin
- Department of Cell and Developmental Biology, University of Michigan School of Medicine Ann Arbor, MI, USA ; Cellular and Molecular Biology Graduate Program, University of Michigan School of Medicine Ann Arbor, MI, USA
| | - Roman J Giger
- Department of Cell and Developmental Biology, University of Michigan School of Medicine Ann Arbor, MI, USA ; Department of Neurology, University of Michigan School of Medicine Ann Arbor, MI, USA
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116
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Yungher BJ, Luo X, Salgueiro Y, Blackmore MG, Park KK. Viral vector-based improvement of optic nerve regeneration: characterization of individual axons' growth patterns and synaptogenesis in a visual target. Gene Ther 2015; 22:811-21. [PMID: 26005861 PMCID: PMC4600032 DOI: 10.1038/gt.2015.51] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 04/10/2015] [Accepted: 05/05/2015] [Indexed: 12/21/2022]
Abstract
Lack of axon growth ability in the central nervous system poses a major barrier to achieving functional connectivity after injury. Thus, a non-transgenic regenerative approach to reinnervating targets has important implications in clinical and research settings. Previous studies using knockout (KO) mice have demonstrated long distance axon regeneration. Using an optic nerve injury model, here we evaluate the efficacy of viral, RNAi and pharmacological approaches that target the PTEN and STAT3 pathways to improve long distance axon regeneration in wild type (WT) mice. Our data show that adeno-associated virus (AAV) expressing short hairpin RNA (shRNA) against PTEN (shPTEN) enhances retinal ganglion cell axon regeneration after crush injury. However, compared to the previous data in PTEN KO mice, AAV-shRNA results in a lesser degree of regeneration, likely due to incomplete gene silencing inherent to RNAi. In comparison, an extensive enhancement in regeneration is seen when AAV-shPTEN is coupled to AAV encoding ciliary neurotrophic factor (CNTF) and to a cyclic adenosine monophosphate (cAMP) analogue, allowing axons to travel long distances and reach their target. We apply whole tissue imaging that facilitates three-dimensional visualization of single regenerating axons and document heterogeneous terminal patterns in the targets. This shows that some axonal populations generate extensive arbors and make synapses with the target neurons. Collectively, we show a combinatorial viral RNAi and pharmacological strategy that improves long distance regeneration in WT animals and provide single fiber projection data that indicates a degree of preservation of target recognition.
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Affiliation(s)
- B J Yungher
- Miami Project to Cure Paralysis, Department of Neurosurgery, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - X Luo
- Miami Project to Cure Paralysis, Department of Neurosurgery, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Y Salgueiro
- Miami Project to Cure Paralysis, Department of Neurosurgery, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - M G Blackmore
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, USA
| | - K K Park
- Miami Project to Cure Paralysis, Department of Neurosurgery, University of Miami, Miller School of Medicine, Miami, FL, USA
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van der Kallen LR, Eggers R, Ehlert EM, Verhaagen J, Smit AB, van Kesteren RE. Genetic Deletion of the Transcriptional Repressor NFIL3 Enhances Axon Growth In Vitro but Not Axonal Repair In Vivo. PLoS One 2015; 10:e0127163. [PMID: 25993115 PMCID: PMC4438979 DOI: 10.1371/journal.pone.0127163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 04/13/2015] [Indexed: 01/04/2023] Open
Abstract
Axonal regeneration after injury requires the coordinated expression of genes in injured neurons. We previously showed that either reducing expression or blocking function of the transcriptional repressor NFIL3 activates transcription of regeneration-associated genes Arg1 and Gap43 and strongly promotes axon outgrowth in vitro. Here we tested whether genetic deletion or dominant-negative inhibition of NFIL3 could promote axon regeneration and functional recovery after peripheral nerve lesion in vivo. Contrary to our expectations, we observed no changes in the expression of regeneration-associated genes and a significant delay in functional recovery following genetic deletion of Nfil3. When NFIL3 function was inhibited specifically in dorsal root ganglia prior to sciatic nerve injury, we observed a decrease in regenerative axon growth into the distal nerve segment rather than an increase. Finally, we show that deletion of Nfil3 changes sciatic nerve lesion-induced expression in dorsal root ganglia of genes that are not typically involved in regeneration, including several olfactory receptors and developmental transcription factors. Together our findings show that removal of NFIL3 in vivo does not recapitulate the regeneration-promoting effects that were previously observed in vitro, indicating that in vivo transcriptional control of regeneration is probably more complex and more robust against perturbation than in vitro data may suggest.
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Affiliation(s)
- Loek R. van der Kallen
- Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, The Netherlands
| | - Ruben Eggers
- Department of Neuroregeneration, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - Erich M. Ehlert
- Department of Neuroregeneration, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - Joost Verhaagen
- Department of Neuroregeneration, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - August B. Smit
- Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, The Netherlands
| | - Ronald E. van Kesteren
- Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, The Netherlands
- * E-mail:
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Siddiq MM, Hannila SS, Carmel JB, Bryson JB, Hou J, Nikulina E, Willis MR, Mellado W, Richman EL, Hilaire M, Hart RP, Filbin MT. Metallothionein-I/II Promotes Axonal Regeneration in the Central Nervous System. J Biol Chem 2015; 290:16343-56. [PMID: 25947372 DOI: 10.1074/jbc.m114.630574] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Indexed: 11/06/2022] Open
Abstract
The adult CNS does not spontaneously regenerate after injury, due in large part to myelin-associated inhibitors such as myelin-associated glycoprotein (MAG), Nogo-A, and oligodendrocyte-myelin glycoprotein. All three inhibitors can interact with either the Nogo receptor complex or paired immunoglobulin-like receptor B. A conditioning lesion of the sciatic nerve allows the central processes of dorsal root ganglion (DRG) neurons to spontaneously regenerate in vivo after a dorsal column lesion. After a conditioning lesion, DRG neurons are no longer inhibited by myelin, and this effect is cyclic AMP (cAMP)- and transcription-dependent. Using a microarray analysis, we identified several genes that are up-regulated both in adult DRGs after a conditioning lesion and in DRG neurons treated with cAMP analogues. One gene that was up-regulated under both conditions is metallothionein (MT)-I. We show here that treatment with two closely related isoforms of MT (MT-I/II) can overcome the inhibitory effects of both myelin and MAG for cortical, hippocampal, and DRG neurons. Intrathecal delivery of MT-I/II to adult DRGs also promotes neurite outgrowth in the presence of MAG. Adult DRGs from MT-I/II-deficient mice extend significantly shorter processes on MAG compared with wild-type DRG neurons, and regeneration of dorsal column axons does not occur after a conditioning lesion in MT-I/II-deficient mice. Furthermore, a single intravitreal injection of MT-I/II after optic nerve crush promotes axonal regeneration. Mechanistically, MT-I/II ability to overcome MAG-mediated inhibition is transcription-dependent, and MT-I/II can block the proteolytic activity of α-secretase and the activation of PKC and Rho in response to soluble MAG.
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Affiliation(s)
- Mustafa M Siddiq
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Sari S Hannila
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Jason B Carmel
- the W. M. Keck Center for Collaborative Neuroscience and Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854
| | - John B Bryson
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Jianwei Hou
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Elena Nikulina
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Matthew R Willis
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Wilfredo Mellado
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Erica L Richman
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Melissa Hilaire
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
| | - Ronald P Hart
- the W. M. Keck Center for Collaborative Neuroscience and Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854
| | - Marie T Filbin
- From the Department of Biological Sciences, Hunter College, City University of New York, New York 10065 and
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119
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Hosseini Farahabadi SS, Ghaedi K, Ghazvini Zadegan F, Karbalaie K, Rabiee F, Nematollahi M, Baharvand H, Nasr-Esfahani MH. ERK1/2 is a key regulator of Fndc5 and PGC1α expression during neural differentiation of mESCs. Neuroscience 2015; 297:252-61. [PMID: 25869623 DOI: 10.1016/j.neuroscience.2015.03.069] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 03/24/2015] [Accepted: 03/29/2015] [Indexed: 12/31/2022]
Abstract
Fibronectin type III domain containing 5 (Fndc5) has already been distinguished to be involved in neural differentiation. However, cellular events of Fndc5 function are still ambiguous in the nervous system. One approach to shed light on duty of this protein in the nervous system is to find its cross-talks with various signaling pathways with defined characteristics and roles. Identification of the underlying molecular mechanism which controls Fndc5 expression and switches its activity up and down enables us to find out the Fndc5 functional map in the nervous system and other human body systems. Retinoic acid (RA) is a bio-small molecule which exerts its role as a neural inducer in the neurodevelopmental process of neural tube. RA up-regulates the expression of various genes involved in neural differentiation process via two distinct pathways: the genomic and the non-genomic. Our previous study has revealed that RA induces Fndc5 expression during neural differentiation process. In this study we have evaluated our hypothesis about the non-genomic up regulation of Fndc5 expression by RA. Interestingly we have identified that there is an association between ERK signaling pathway and Fndc5 expression. Furthermore, inhibition of this pathway by PD0325901 dramatically reduced Fndc5 mRNA level, while activating the pathway up-regulated Fndc5 transcription. In addition, it has been proven that ERK1/2 modulation via RA has more significant controlling effect on Fndc5 promoter rather than bFGF. This led us to conclude that RA enhances Fndc5 expression through a non-genomic pathway via the ERK signaling pathway.
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Affiliation(s)
- S S Hosseini Farahabadi
- Cell and Molecular Biology Division, Biology Department, School of Sciences, University of Isfahan, Isfahan, Iran
| | - K Ghaedi
- Cell and Molecular Biology Division, Biology Department, School of Sciences, University of Isfahan, Isfahan, Iran; Department of Cellular Biotechnology at Cell Science Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran.
| | - F Ghazvini Zadegan
- Department of Cellular Biotechnology at Cell Science Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - K Karbalaie
- Department of Cellular Biotechnology at Cell Science Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - F Rabiee
- Department of Cellular Biotechnology at Cell Science Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - M Nematollahi
- Department of Cellular Biotechnology at Cell Science Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - H Baharvand
- Department of Stem Cells and Developmental Biology at Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran; Department of Developmental Biology, University of Science and Culture, ACECR, Tehran, Iran
| | - M-H Nasr-Esfahani
- Department of Cellular Biotechnology at Cell Science Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran.
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120
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Wood MD, Mackinnon SE. Pathways regulating modality-specific axonal regeneration in peripheral nerve. Exp Neurol 2015; 265:171-5. [PMID: 25681572 DOI: 10.1016/j.expneurol.2015.02.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 01/08/2015] [Accepted: 02/05/2015] [Indexed: 12/14/2022]
Abstract
Following peripheral nerve injury, the distal nerve is primed for regenerating axons by generating a permissive environment replete with glial cells, cytokines, and neurotrophic factors to encourage axonal growth. However, increasing evidence demonstrates that regenerating axons within peripheral nerves still encounter axonal-growth inhibitors, such as chondroitin sulfate proteoglycans. Given the generally poor clinical outcomes following peripheral nerve injury and reconstruction, the use of pharmacological therapies to augment axonal regeneration and overcome inhibitory signals has gained considerable interest. Joshi et al. (2014) have provided evidence for preferential or modality-specific (motor versus sensory) axonal growth and regeneration due to inhibitory signaling from Rho-associated kinase (ROCK) pathway regulation. By providing inhibition to the ROCK signaling pathway through Y-27632, they demonstrate that motor neurons regenerating their axons are impacted to a greater extent compared to sensory neurons. In light of this evidence, we briefly review the literature regarding modality-specific axonal regeneration to provide context to their findings. We also describe potential and novel barriers, such as senescent Schwann cells, which provide additional axonal-growth inhibitory factors for future consideration following peripheral nerve injury.
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Affiliation(s)
- Matthew D Wood
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Washington University School of Medicine, Campus Box 8238, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
| | - Susan E Mackinnon
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Washington University School of Medicine, Campus Box 8238, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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121
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PASTUHOV SI, HISAMOTO N, MATSUMOTO K. MAP kinase cascades regulating axon regeneration in C. elegans. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2015; 91:63-75. [PMID: 25792136 PMCID: PMC4410086 DOI: 10.2183/pjab.91.63] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 01/13/2015] [Indexed: 06/04/2023]
Abstract
Mitogen-activated protein kinase (MAPK) signaling cascades are activated by diverse stimuli such as growth factors, cytokines, neurotransmitters and various types of cellular stress. Our evolving understanding of these signal cascades has been facilitated by genetic analyses and physiological characterization in model organisms such as the nematode Caenorhabditis elegans. Genetic and biochemical studies in C. elegans have shed light on the physiological roles of MAPK cascades in the control of cell fate decision, neuronal function and immunity. Recently it was demonstrated that MAPK signaling is also important for axon regeneration in C. elegans, and the use of C. elegans as a model system has significantly advanced our understanding of the largely conserved molecular mechanisms underlying axon regeneration. This review summarizes our current understanding of the role and regulation of MAPK signaling in C. elegans axon regeneration.
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Affiliation(s)
- Strahil Iv. PASTUHOV
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, Japan
| | - Naoki HISAMOTO
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, Japan
| | - Kunihiro MATSUMOTO
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, Japan
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122
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Stiles TL, Kapiloff MS, Goldberg JL. The role of soluble adenylyl cyclase in neurite outgrowth. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1842:2561-8. [PMID: 25064589 PMCID: PMC4262618 DOI: 10.1016/j.bbadis.2014.07.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 07/11/2014] [Accepted: 07/15/2014] [Indexed: 12/25/2022]
Abstract
Axon regeneration in the mature central nervous system is limited by extrinsic inhibitory signals and a postnatal decline in neurons' intrinsic growth capacity. Neuronal levels of the second messenger cAMP are important in regulating both intrinsic growth capacity and neurons' responses to extrinsic factors. Approaches which increase intracellular cAMP in neurons enhance neurite outgrowth and facilitate regeneration after injury. Thus, understanding the factors which affect cAMP in neurons is of potential therapeutic importance. Recently, soluble adenylyl cyclase (sAC, ADCY10), the ubiquitous, non-transmembrane adenylyl cyclase, was found to play a key role in neuronal survival and axon growth. sAC is activated by bicarbonate and cations and may translate physiologic signals from metabolism and electrical activity into a neuron's decision to survive or regenerate. Here we critically review the literature surrounding sAC and cAMP signaling in neurons to further elucidate the potential role of sAC signaling in neurite outgrowth and regeneration. This article is part of a Special Issue entitled: The role of soluble adenylyl cyclase in health and disease.
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Affiliation(s)
- Travis L Stiles
- Shiley Eye Center, University of California, San Diego, CA 92093, USA
| | - Michael S Kapiloff
- Departments of Pediatrics and Medicine, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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123
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Apara A, Goldberg JL. Molecular mechanisms of the suppression of axon regeneration by KLF transcription factors. Neural Regen Res 2014; 9:1418-21. [PMID: 25317150 PMCID: PMC4192940 DOI: 10.4103/1673-5374.139454] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/22/2014] [Indexed: 01/11/2023] Open
Abstract
Molecular mechanisms of the Krüppel-like family of transcription factors (KLFs) have been studied more in proliferating cells than in post-mitotic cells such as neurons. We recently found that KLFs regulate intrinsic axon growth ability in central nervous system (CNS) neurons including retinal ganglion cells, and hippocampal and cortical neurons. With at least 15 of 17 KLF family members expressed in neurons and at least 5 structurally unique subfamilies, it is important to determine how this complex family functions in neurons to regulate the intricate genetic programs of axon growth and regeneration. By characterizing the molecular mechanisms of the KLF family in the nervous system, including binding partners and gene targets, and comparing them to defined mechanisms defined outside the nervous system, we may better understand how KLFs regulate neurite growth and axon regeneration.
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Affiliation(s)
| | - Jeffrey L Goldberg
- Shiley Eye Center, University of California San Diego, La Jolla, CA, USA
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124
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Ma TC, Barco A, Ratan RR, Willis DE. cAMP-responsive element-binding protein (CREB) and cAMP co-regulate activator protein 1 (AP1)-dependent regeneration-associated gene expression and neurite growth. J Biol Chem 2014; 289:32914-25. [PMID: 25296755 DOI: 10.1074/jbc.m114.582460] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
To regenerate damaged axons, neurons must express a cassette of regeneration-associated genes (RAGs) that increases intrinsic growth capacity and confers resistance to extrinsic inhibitory cues. Here we show that dibutyrl-cAMP or forskolin combined with constitutive-active CREB are superior to either agent alone in driving neurite growth on permissive and inhibitory substrates. Of the RAGs examined, only arginase 1 (Arg1) expression correlated with the increased neurite growth induced by the cAMP/CREB combination, both of which were AP1-dependent. This suggests that cAMP-induced AP1 activity is necessary and interacts with CREB to drive expression of RAGs relevant for regeneration and demonstrates that combining a small molecule (cAMP) with an activated transcription factor (CREB) stimulates the gene expression necessary to enhance axonal regeneration.
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Affiliation(s)
- Thong C Ma
- From the Burke-Cornell Medical Research Institute, White Plains, New York 10605 and
| | - Angel Barco
- the Instituto de Neurociencias de Alicante (Universidad Miguel Hernández de Elche-Consejo Superior de Investigaciones Científicas), San Juan de Alicante, 03550 Alicante, Spain
| | - Rajiv R Ratan
- From the Burke-Cornell Medical Research Institute, White Plains, New York 10605 and
| | - Dianna E Willis
- From the Burke-Cornell Medical Research Institute, White Plains, New York 10605 and
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125
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Fagoe ND, van Heest J, Verhaagen J. Spinal cord injury and the neuron-intrinsic regeneration-associated gene program. Neuromolecular Med 2014; 16:799-813. [PMID: 25269879 DOI: 10.1007/s12017-014-8329-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 09/20/2014] [Indexed: 12/14/2022]
Abstract
Spinal cord injury (SCI) affects millions of people worldwide and causes a significant physical, emotional, social and economic burden. The main clinical hallmark of SCI is the permanent loss of motor, sensory and autonomic function below the level of injury. In general, neurons of the central nervous system (CNS) are incapable of regeneration, whereas injury to the peripheral nervous system is followed by axonal regeneration and usually results in some degree of functional recovery. The weak neuron-intrinsic regeneration-associated gene (RAG) response upon injury is an important reason for the failure of neurons in the CNS to regenerate an axon. This response consists of the expression of many RAGs, including regeneration-associated transcription factors (TFs). Regeneration-associated TFs are potential key regulators of the RAG program. The function of some regeneration-associated TFs has been studied in transgenic and knock-out mice and by adeno-associated viral vector-mediated overexpression in injured neurons. Here, we review these studies and propose that AAV-mediated gene delivery of combinations of regeneration-associated TFs is a potential strategy to activate the RAG program in injured CNS neurons and achieve long-distance axon regeneration.
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Affiliation(s)
- Nitish D Fagoe
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, an Institute of the Royal Academy of Arts and Sciences, Meibergdreef 47, 1105 BA, Amsterdam, The Netherlands,
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126
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Chan KM, Gordon T, Zochodne DW, Power HA. Improving peripheral nerve regeneration: from molecular mechanisms to potential therapeutic targets. Exp Neurol 2014; 261:826-35. [PMID: 25220611 DOI: 10.1016/j.expneurol.2014.09.006] [Citation(s) in RCA: 132] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 08/29/2014] [Accepted: 09/05/2014] [Indexed: 11/19/2022]
Abstract
Peripheral nerve injury is common especially among young individuals. Although injured neurons have the ability to regenerate, the rate is slow and functional outcomes are often poor. Several potential therapeutic agents have shown considerable promise for improving the survival and regenerative capacity of injured neurons. These agents are reviewed within the context of their molecular mechanisms. The PI3K/Akt and Ras/ERK signaling cascades play a key role in neuronal survival. A number of agents that target these pathways, including erythropoietin, tacrolimus, acetyl-l-carnitine, n-acetylcysteine and geldanamycin have been shown to be effective. Trk receptor signaling events that up-regulate cAMP play an important role in enhancing the rate of axonal outgrowth. Agents that target this pathway including rolipram, testosterone, fasudil, ibuprofen and chondroitinase ABC hold considerable promise for human application. A tantalizing prospect is to combine different molecular targeting strategies in complementary pathways to optimize their therapeutic effects. Although further study is needed prior to human trials, these modalities could open a new horizon in the clinical arena that has so far been elusive.
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Affiliation(s)
- K Ming Chan
- Division of Physical Medicine and Rehabilitation, University of Alberta, Edmonton, Alberta, Canada; Centre for Neuroscience, University of Alberta, Canada.
| | - Tessa Gordon
- Division of Physical Medicine and Rehabilitation, University of Alberta, Edmonton, Alberta, Canada; Centre for Neuroscience, University of Alberta, Canada; Division of Plastic Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Douglas W Zochodne
- Department of Clinical Neuroscience, University of Calgary, Calgary, Alberta, Canada
| | - Hollie A Power
- Division of Plastic Surgery, University of Alberta, Canada
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127
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Zagrebelsky M, Korte M. Maintaining stable memory engrams: new roles for Nogo-A in the CNS. Neuroscience 2014; 283:17-25. [PMID: 25168730 DOI: 10.1016/j.neuroscience.2014.08.030] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 08/18/2014] [Accepted: 08/19/2014] [Indexed: 12/15/2022]
Abstract
Nogo-A interaction with its different receptors (Nogo receptor 1 (NgR1), S1P receptor 2 (S1PR2), paired immunoglobulin-like receptor B (PirB)) restricts plasticity and growth-dependent processes leading, via the activation of different signaling pathway to the stabilization of the neuronal networks (either developmentally or during processes of memory consolation in the mature nervous system). Taking away these molecular brakes might allow for the induction of extensive structural and functional rearrangements and might promote compensatory growth processes after an injury of the CNS, in cortical structures as well as in the spinal cord. However, it is important to keep in mind that this could as well be a dangerous endeavor, since it might facilitate unwanted and unnecessary (and probably even maladaptive) neuronal connections.
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Affiliation(s)
- M Zagrebelsky
- TU Braunschweig, Zoological Institute, Division of Cellular Neurobiology, Braunschweig, Germany
| | - M Korte
- TU Braunschweig, Zoological Institute, Division of Cellular Neurobiology, Braunschweig, Germany.
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128
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Cyclic AMP signaling: a molecular determinant of peripheral nerve regeneration. BIOMED RESEARCH INTERNATIONAL 2014; 2014:651625. [PMID: 25177696 PMCID: PMC4142170 DOI: 10.1155/2014/651625] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Accepted: 06/30/2014] [Indexed: 12/11/2022]
Abstract
Disruption of axonal integrity during injury to the peripheral nerve system (PNS) sets into motion a cascade of responses that includes inflammation, Schwann cell mobilization, and the degeneration of the nerve fibers distal to the injury site. Yet, the injured PNS differentiates itself from the injured central nervous system (CNS) in its remarkable capacity for self-recovery, which, depending upon the length and type of nerve injury, involves a series of molecular events in both the injured neuron and associated Schwann cells that leads to axon regeneration, remyelination repair, and functional restitution. Herein we discuss the essential function of the second messenger, cyclic adenosine monophosphate (cyclic AMP), in the PNS repair process, highlighting the important role the conditioning lesion paradigm has played in understanding the mechanism(s) by which cyclic AMP exerts its proregenerative action. Furthermore, we review the studies that have therapeutically targeted cyclic AMP to enhance endogenous nerve repair.
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129
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PI3K-GSK3 signalling regulates mammalian axon regeneration by inducing the expression of Smad1. Nat Commun 2014; 4:2690. [PMID: 24162165 PMCID: PMC3836055 DOI: 10.1038/ncomms3690] [Citation(s) in RCA: 142] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 09/27/2013] [Indexed: 01/20/2023] Open
Abstract
In contrast to neurons in the central nervous system, mature neurons in the mammalian peripheral nervous system (PNS) can regenerate axons after injury, in part, by enhancing intrinsic growth competence. However, the signalling pathways that enhance the growth potential and induce spontaneous axon regeneration remain poorly understood. Here we reveal that phosphatidylinositol 3-kinase (PI3K) signalling is activated in response to peripheral axotomy and that PI3K pathway is required for sensory axon regeneration. Moreover, we show that glycogen synthase kinase 3 (GSK3), rather than mammalian target of rapamycin, mediates PI3K-dependent augmentation of the growth potential in the PNS. Furthermore, we show that PI3K-GSK3 signal is conveyed by the induction of a transcription factor Smad1 and that acute depletion of Smad1 in adult mice prevents axon regeneration in vivo. Together, these results suggest PI3K-GSK3-Smad1 signalling as a central module for promoting sensory axon regeneration in the mammalian nervous system.
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130
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Zhang Y, Hu H, Tian T, Zhang L, Zhao D, Wu Q, Chang Y, Wang Q, Zhou S, Feng G, Huang F. Mst3b promotes spinal cord neuronal regeneration by promoting growth cone branching out in spinal cord injury rats. Mol Neurobiol 2014; 51:1144-57. [PMID: 24990316 DOI: 10.1007/s12035-014-8785-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 06/09/2014] [Indexed: 01/05/2023]
Abstract
Spinal cord injury is a severe clinical problem, and research searching activity molecular that can promote spinal cord injury repairing is very prevalent. Mst3b can promote repair of damaged peripheral nerves and the optic nerve, but has been rarely reported in spinal cord injury research. Through detecting its expression in different periods of injured spinal cord, we found that the expression of Mst3b was significantly upregulated in injured spinal cord neurons. Increasing Mst3b expression using adenovirus in vivo and in vitro promoted axonal regeneration of spinal cord neurons, which led to behavioral and electrophysiological improvement. Downregulation of Mst3b level had the adverse effects. Increasing Mst3b expression in PC12 cells resulted in an elevation of P42/44(MAPK) and LIMK/Cofilin activation. These results identified Mst3b as a powerful regulator for promoting spinal cord injury recovery through the P42/44(MAPK) and LIMK/Cofilin signaling pathways.
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Affiliation(s)
- Yuqiang Zhang
- Institute of Human Anatomy and Histology and Embryology, Otology & Neuroscience Center, Binzhou Medical University, 346 Guanhai Road, Laishan, Shandong Province, 264003, China
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131
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Abstract
The growth of axons is an intricately regulated process involving intracellular signaling cascades and gene transcription. We had previously shown that the stimulus-dependent transcription factor, serum response factor (SRF), plays a critical role in regulating axon growth in the mammalian brain. However, the molecular mechanisms underlying SRF-dependent axon growth remains unknown. Here we report that SRF is phosphorylated and activated by GSK-3 to promote axon outgrowth in mouse hippocampal neurons. GSK-3 binds to and directly phosphorylates SRF on a highly conserved serine residue. This serine phosphorylation is necessary for SRF activity and for its interaction with MKL-family cofactors, MKL1 and MKL2, but not with TCF-family cofactor, ELK-1. Axonal growth deficits caused by GSK-3 inhibition could be rescued by expression of a constitutively active SRF. The SRF target gene and actin-binding protein, vinculin, is sufficient to overcome the axonal growth deficits of SRF-deficient and GSK-3-inhibited neurons. Furthermore, short hairpin RNA-mediated knockdown of vinculin also attenuated axonal growth. Thus, our findings reveal a novel phosphorylation and activation of SRF by GSK-3 that is critical for SRF-dependent axon growth in mammalian central neurons.
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132
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Cyclic AMP and the regeneration of retinal ganglion cell axons. Int J Biochem Cell Biol 2014; 56:66-73. [PMID: 24796847 DOI: 10.1016/j.biocel.2014.04.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 04/10/2014] [Accepted: 04/22/2014] [Indexed: 01/12/2023]
Abstract
In this paper we present a brief review of studies that have reported therapeutic benefits of elevated cAMP on plasticity and regeneration after injury to the central nervous system (CNS). We also provide new data on the cellular mechanisms by which elevation of cyclic adenosine monophosphate (cAMP) promotes cytokine driven regeneration of adult CNS axons, using the visual system as the experimental model. cAMP is a second messenger for many intracellular signalling pathways. Elevation of cAMP in the eye by intravitreal injection of the cell permeant analogue (8-(4-chlorophenylthio)-adenosine-3',5'-cyclic monophosphate; CPT-cAMP), when added to recombinant ciliary neurotrophic factor (rCNTF), significantly enhances rCNTF-induced regeneration of adult rat retinal ganglion cell (RGC) axons into peripheral nerve (PN) grafted onto transected optic nerve. This effect is mediated to some extent by protein kinase A (PKA) signalling, but CPT-cAMP also acts via PI3K/Akt signalling to reduce suppressor of cytokine signalling protein 3 (SOCS3) activity in RGCs. Another target for cAMP is the exchange protein activated by cAMP (Epac), which can also mediate cAMP-induced axonal growth. Here we describe some novel results and discuss to what extent the pro-regenerative effects of CPT-cAMP on adult RGCs are mediated via Epac as well as via PKA-dependent pathways. We used the established PN-optic nerve graft model and quantified the survival and regenerative growth of adult rat RGCs after intravitreal injection of rCNTF in combination with a selective activator of PKA and/or a specific activator of Epac. Viable RGCs were identified by βIII-tubulin immunohistochemistry and regenerating RGCs retrogradely labelled and quantified after an injection of fluorogold into the distal end of the PN grafts, 4 weeks post-transplantation. The specific agonists of either PKA or Epac were both effective in enhancing the effects of rCNTF on RGC axonal regeneration, but interestingly, injections that combined rCNTF with both agonists were significantly less effective. The results are discussed in relation to previous CPT-cAMP studies on RGCs, and we also consider the need to modulate cAMP levels in order to obtain the most functionally effective regenerative response after CNS trauma. This article is part of a directed issue entitled: Regenerative Medicine: the challenge of translation.
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133
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Vishwakarma SK, Bardia A, Tiwari SK, Paspala SA, Khan AA. Current concept in neural regeneration research: NSCs isolation, characterization and transplantation in various neurodegenerative diseases and stroke: A review. J Adv Res 2014; 5:277-294. [PMID: 25685495 PMCID: PMC4294738 DOI: 10.1016/j.jare.2013.04.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 04/10/2013] [Accepted: 04/28/2013] [Indexed: 12/14/2022] Open
Abstract
Since last few years, an impressive amount of data has been generated regarding the basic in vitro and in vivo biology of neural stem cells (NSCs) and there is much far hope for the success in cell replacement therapies for several human neurodegenerative diseases and stroke. The discovery of adult neurogenesis (the endogenous production of new neurons) in the mammalian brain more than 40 years ago has resulted in a wealth of knowledge about stem cells biology in neuroscience research. Various studies have done in search of a suitable source for NSCs which could be used in animal models to understand the basic and transplantation biology before treating to human. The difficulties in isolating pure population of NSCs limit the study of neural stem behavior and factors that regulate them. Several studies on human fetal brain and spinal cord derived NSCs in animal models have shown some interesting results for cell replacement therapies in many neurodegenerative diseases and stroke models. Also the methods and conditions used for in vitro culture of these cells provide an important base for their applicability and specificity in a definite target of the disease. Various important developments and modifications have been made in stem cells research which is needed to be more specified and enrolment in clinical studies using advanced approaches. This review explains about the current perspectives and suitable sources for NSCs isolation, characterization, in vitro proliferation and their use in cell replacement therapies for the treatment of various neurodegenerative diseases and strokes.
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Affiliation(s)
- Sandeep K. Vishwakarma
- Centre for Liver Research and Diagnostics, Deccan College of Medical Sciences, Kanchanbagh, Hyderabad, 500 058 Andhra Pradesh, India
- Paspala Advanced Neural (PAN) Research Foundation, Narayanguda, Hyderabad, 500 029 Andhra Pradesh, India
| | - Avinash Bardia
- Centre for Liver Research and Diagnostics, Deccan College of Medical Sciences, Kanchanbagh, Hyderabad, 500 058 Andhra Pradesh, India
| | - Santosh K. Tiwari
- Centre for Liver Research and Diagnostics, Deccan College of Medical Sciences, Kanchanbagh, Hyderabad, 500 058 Andhra Pradesh, India
| | - Syed A.B. Paspala
- Centre for Liver Research and Diagnostics, Deccan College of Medical Sciences, Kanchanbagh, Hyderabad, 500 058 Andhra Pradesh, India
- Paspala Advanced Neural (PAN) Research Foundation, Narayanguda, Hyderabad, 500 029 Andhra Pradesh, India
| | - Aleem A. Khan
- Centre for Liver Research and Diagnostics, Deccan College of Medical Sciences, Kanchanbagh, Hyderabad, 500 058 Andhra Pradesh, India
- Paspala Advanced Neural (PAN) Research Foundation, Narayanguda, Hyderabad, 500 029 Andhra Pradesh, India
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134
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Ohtake Y, Park D, Muneer PMA, Li H, Xu B, Sharma K, Smith GM, Selzer ME, Li S. The effect of systemic PTEN antagonist peptides on axon growth and functional recovery after spinal cord injury. Biomaterials 2014; 35:4610-26. [PMID: 24630093 PMCID: PMC4195449 DOI: 10.1016/j.biomaterials.2014.02.037] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Accepted: 02/20/2014] [Indexed: 10/25/2022]
Abstract
Knockout studies suggest that PTEN limits the regenerative capacities of CNS axons as a dominant antagonist of PI3 kinase, but the transgenic approach is not feasible for treating patients. Although application of bisperoxovanadium may block PTEN function, it is a general inhibitor of phosphotyrosine phosphatases and may target enzymes other than PTEN, causing side effects and preventing firm conclusions about PTEN inhibition on regulating neuronal growth. A pharmacological method to selectively suppress PTEN post-injury could be a valuable strategy for promoting CNS axon regeneration. We identified PTEN antagonist peptides (PAPs) by targeting PTEN critical functional domains and evaluated their efficacy for promoting axon growth. Four PAPs (PAP 1-4) bound to PTEN protein expressed in COS7 cells and blocked PTEN signaling in vivo. Subcutaneous administration of PAPs initiated two days after dorsal over-hemisection injury significantly stimulated growth of descending serotonergic fibers in the caudal spinal cord of adult mice. Systemic PAPs induce significant sprouting of corticospinal fibers in the rostral spinal cord and limited growth of corticospinal axons in the caudal spinal cord. More importantly, PAP treatment enhanced recovery of locomotor function in adult rodents with spinal cord injury. This study may facilitate development of effective therapeutic agents for CNS injuries.
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Affiliation(s)
- Yosuke Ohtake
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Dongsun Park
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - P M Abdul Muneer
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Hui Li
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Bin Xu
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Kartavya Sharma
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75390-8813, USA
| | - George M Smith
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Neuroscience, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Michael E Selzer
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Neurology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Shuxin Li
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA.
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135
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S6 kinase inhibits intrinsic axon regeneration capacity via AMP kinase in Caenorhabditis elegans. J Neurosci 2014; 34:758-63. [PMID: 24431434 DOI: 10.1523/jneurosci.2886-13.2014] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The ability of axons to regrow after injury is determined by the complex interplay of intrinsic growth programs and external cues. In Caenorhabditis elegans mechanosensory neuron, axons exhibit robust regenerative regrowth following laser axotomy. By surveying conserved metabolic signaling pathways, we have identified the ribosomal S6 kinase RSKS-1 as a new cell-autonomous inhibitor of axon regeneration. RSKS-1 is not required for axonal development but inhibits axon regrowth after injury in multiple neuron types. Loss of function in rsks-1 results in more rapid growth cone formation after injury and accelerates subsequent axon extension. The enhanced regrowth of rsks-1 mutants is partly dependent on the DLK-1 MAPK cascade. An essential output of RSKS-1 in axon regrowth is the metabolic sensor AMP kinase, AAK-2. We further show that the antidiabetic drug phenformin, which activates AMP kinase, can promote axon regrowth. Our data reveal a new function for an S6 kinase acting through an AMP kinase in regenerative growth of injured axons.
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136
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Warren PM, Alilain WJ. The challenges of respiratory motor system recovery following cervical spinal cord injury. PROGRESS IN BRAIN RESEARCH 2014; 212:173-220. [DOI: 10.1016/b978-0-444-63488-7.00010-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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137
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Carballosa-Gonzalez MM, Vitores A, Hentall ID. Hindbrain raphe stimulation boosts cyclic adenosine monophosphate and signaling proteins in the injured spinal cord. Brain Res 2013; 1543:165-72. [PMID: 24246733 DOI: 10.1016/j.brainres.2013.11.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 11/05/2013] [Accepted: 11/09/2013] [Indexed: 12/20/2022]
Abstract
Early recovery from incomplete spinal cord contusion is improved by prolonged stimulation of the hindbrain's serotonergic nucleus raphe magnus (NRM). Here we examine whether increases in cyclic adenosine monophosphate (cAMP), an intracellular signaling molecule with several known restorative actions on damaged neural tissue, could play a role. Subsequent changes in cAMP-dependent phosphorylation of protein kinase A (PKA) and PKA-dependent phosphorylation of the transcription factor "cAMP response element-binding protein" (CREB) are also analyzed. Rats with moderate weight-drop injury at segment T8 received 2h of NRM stimulation beginning three days after injury, followed immediately by separate extraction of cervical, thoracic and lumbar spinal cord for immunochemical assay. Controls lacked injury, stimulation or both. Injury reduced cAMP levels to under half of normal in all three spinal regions. NRM stimulation completely restored these levels, while producing no significant change in non-injured rats. Pretreatment with the 5-HT7 receptor antagonist pimozide (1 mg/kg, intraperitoneal) lowered cAMP in non-injured rats to injury amounts, which were unchanged by NRM stimulation. The phosphorylated fraction of PKA (pPKA) and CREB (pCREB) was reduced significantly in all three regions after SCI and restored by NRM stimulation, except for pCREB in lumbar segments. In conclusion, SCI produces spreading deficits in cAMP, pPKA and pCREB that are reversible by Gs protein-coupled 5-HT receptors responding to raphe-spinal activity, although these signaling molecules are not reactive to NRM stimulation in normal tissue. These findings can partly explain the benefits of NRM stimulation after SCI.
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Affiliation(s)
| | - Alberto Vitores
- Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Ian D Hentall
- Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, FL, USA.
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138
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Lindner R, Puttagunta R, Di Giovanni S. Epigenetic regulation of axon outgrowth and regeneration in CNS injury: the first steps forward. Neurotherapeutics 2013; 10:771-81. [PMID: 23881454 PMCID: PMC3805867 DOI: 10.1007/s13311-013-0203-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Inadequate axonal sprouting and lack of regeneration limit functional recovery following neurologic injury, such as stroke, brain, and traumatic spinal cord injury. Recently, the enhancement of the neuronal regenerative program has led to promising improvements in axonal sprouting and regeneration in animal models of axonal injury. However, precise knowledge of the essential molecular determinants of this regenerative program remains elusive, thus limiting the choice of fully effective therapeutic strategies. Given that molecular regulation of axonal outgrowth and regeneration requires carefully orchestrated waves of gene expression, both temporally and spatially, epigenetic changes may be an ideal regulatory mechanism to address this unique need. While recent evidence suggests that epigenetic modifications could contribute to the regulation of axonal outgrowth and regeneration following axonal injury in models of stroke, and spinal cord and optic nerve injury, a number of unanswered questions remain. Such questions require systematic investigation of the epigenetic landscape between regenerative and non-regenerative conditions for the potential translation of this knowledge into regenerative strategies in human spinal and brain injury, as well as stroke.
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Affiliation(s)
- Ricco Lindner
- Laboratory for NeuroRegeneration and Repair, Center for Neurology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Otfried-Mueller Strasse 27, 72076 Tuebingen, Germany
| | - Radhika Puttagunta
- Laboratory for NeuroRegeneration and Repair, Center for Neurology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Otfried-Mueller Strasse 27, 72076 Tuebingen, Germany
| | - Simone Di Giovanni
- Laboratory for NeuroRegeneration and Repair, Center for Neurology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Otfried-Mueller Strasse 27, 72076 Tuebingen, Germany
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139
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Cyclic AMP promotes axon regeneration, lesion repair and neuronal survival in lampreys after spinal cord injury. Exp Neurol 2013; 250:31-42. [PMID: 24041988 DOI: 10.1016/j.expneurol.2013.09.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 09/03/2013] [Accepted: 09/08/2013] [Indexed: 01/10/2023]
Abstract
Axon regeneration after spinal cord injury in mammals is inadequate to restore function, illustrating the need to design better strategies for improving outcomes. Increasing the levels of the second messenger cyclic adenosine monophosphate (cAMP) after spinal cord injury enhances axon regeneration across a wide variety of species, making it an excellent candidate molecule that has therapeutic potential. However, several important aspects of the cellular and molecular mechanisms by which cAMP enhances axon regeneration are still unclear, such as how cAMP affects axon growth patterns, the molecular components within growing axon tips, the lesion scar, and neuronal survival. To address these points, we took advantage of the large, identified reticulospinal (RS) neurons in lamprey, a vertebrate that exhibits robust axon regeneration after a complete spinal cord transection. Application of a cAMP analog, db-cAMP, at the time of spinal cord transection increased the number of axons that regenerated across the lesion site. Db-cAMP also promoted axons to regenerate in straighter paths, prevented abnormal axonal growth patterns, increased the levels of synaptotagmin within axon tips, and increased the number of axotomized neurons that survived after spinal cord injury, thereby increasing the pool of neurons available for regeneration. There was also a transient increase in the number of microglia/macrophages and improved repair of the lesion site. Taken together, these data reveal several new features of the cellular and molecular mechanisms underlying cAMP-mediated enhancement of axon regeneration, further emphasizing the positive roles for this conserved pathway.
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140
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Do JL, Bonni A, Tuszynski MH. SnoN facilitates axonal regeneration after spinal cord injury. PLoS One 2013; 8:e71906. [PMID: 23936531 PMCID: PMC3732222 DOI: 10.1371/journal.pone.0071906] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 07/04/2013] [Indexed: 12/14/2022] Open
Abstract
Adult CNS neurons exhibit a reduced capacity for growth compared to developing neurons, due in part to downregulation of growth-associated genes as development is completed. We tested the hypothesis that SnoN, an embryonically regulated transcription factor that specifies growth of the axonal compartment, can enhance growth in injured adult neurons. In vitro, SnoN overexpression in dissociated adult DRG neuronal cultures significantly enhanced neurite outgrowth. Moreover, TGF-β1, a negative regulator of SnoN, inhibited neurite outgrowth, and SnoN over-expression overcame this inhibition. We then examined whether SnoN influenced axonal regeneration in vivo: indeed, expression of a mutant form of SnoN resistant to degradation significantly enhanced axonal regeneration following cervical spinal cord injury, despite peri-lesional upregulation of TGF-β1. Thus, a developmental mechanism that specifies extension of the axonal compartment also promotes axonal regeneration after adult CNS injury.
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Affiliation(s)
- Jiun L. Do
- Department of Neurosciences, University of California San Diego, La Jolla, California, United States of America
| | - Azad Bonni
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Mark H. Tuszynski
- Department of Neurosciences, University of California San Diego, La Jolla, California, United States of America
- Veterans Affairs Medical Center, San Diego, California, United States of America
- * E-mail:
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141
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Roet KCD, Franssen EHP, de Bree FM, Essing AHW, Zijlstra SJJ, Fagoe ND, Eggink HM, Eggers R, Smit AB, van Kesteren RE, Verhaagen J. A multilevel screening strategy defines a molecular fingerprint of proregenerative olfactory ensheathing cells and identifies SCARB2, a protein that improves regenerative sprouting of injured sensory spinal axons. J Neurosci 2013; 33:11116-35. [PMID: 23825416 PMCID: PMC6618611 DOI: 10.1523/jneurosci.1002-13.2013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 05/14/2013] [Accepted: 05/15/2013] [Indexed: 11/21/2022] Open
Abstract
Olfactory ensheathing cells (OECs) have neuro-restorative properties in animal models for spinal cord injury, stroke, and amyotrophic lateral sclerosis. Here we used a multistep screening approach to discover genes specifically contributing to the regeneration-promoting properties of OECs. Microarray screening of the injured olfactory pathway and of cultured OECs identified 102 genes that were subsequently functionally characterized in cocultures of OECs and primary dorsal root ganglion (DRG) neurons. Selective siRNA-mediated knockdown of 16 genes in OECs (ADAMTS1, BM385941, FZD1, GFRA1, LEPRE1, NCAM1, NID2, NRP1, MSLN, RND1, S100A9, SCARB2, SERPINI1, SERPINF1, TGFB2, and VAV1) significantly reduced outgrowth of cocultured DRG neurons, indicating that endogenous expression of these genes in OECs supports neurite extension of DRG neurons. In a gain-of-function screen for 18 genes, six (CX3CL1, FZD1, LEPRE1, S100A9, SCARB2, and SERPINI1) enhanced and one (TIMP2) inhibited neurite growth. The most potent hit in both the loss- and gain-of-function screens was SCARB2, a protein that promotes cholesterol secretion. Transplants of fibroblasts that were genetically modified to overexpress SCARB2 significantly increased the number of regenerating DRG axons that grew toward the center of a spinal cord lesion in rats. We conclude that expression of SCARB2 enhances regenerative sprouting and that SCARB2 contributes to OEC-mediated neuronal repair.
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Affiliation(s)
- Kasper C D Roet
- Department of Neuroregeneration, Netherlands Institute for Neuroscience, Institute of the Royal Netherlands Academy of Arts and Sciences, 1105 BA Amsterdam, The Netherlands.
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142
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Paxillin phosphorylation counteracts proteoglycan-mediated inhibition of axon regeneration. Exp Neurol 2013; 248:157-69. [PMID: 23797153 DOI: 10.1016/j.expneurol.2013.06.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 05/29/2013] [Accepted: 06/14/2013] [Indexed: 11/21/2022]
Abstract
In the adult central nervous system, the tips of axons severed by injury are commonly transformed into dystrophic endballs and cease migration upon encountering a rising concentration gradient of inhibitory proteoglycans. However, intracellular signaling networks mediating endball migration failure remain largely unknown. Here we show that manipulation of protein kinase A (PKA) or its downstream adhesion component paxillin can reactivate the locomotive machinery of endballs in vitro and facilitate axon growth after injury in vivo. In dissociated cultures of adult rat dorsal root ganglion neurons, PKA is activated in endballs formed on gradients of the inhibitory proteoglycan aggrecan, and pharmacological inhibition of PKA promotes axon growth on aggrecan gradients most likely through phosphorylation of paxillin at serine 301. Remarkably, pre-formed endballs on aggrecan gradients resume forward migration in response to PKA inhibition. This resumption of endball migration is associated with increased turnover of adhesive point contacts dependent upon paxillin phosphorylation. Furthermore, expression of phosphomimetic paxillin overcomes aggrecan-mediated growth arrest of endballs, and facilitates axon growth after optic nerve crush in vivo. These results point to the importance of adhesion dynamics in restoring endball migration and suggest a potential therapeutic target for axon tract repair.
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143
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Secretory leukocyte protease inhibitor reverses inhibition by CNS myelin, promotes regeneration in the optic nerve, and suppresses expression of the transforming growth factor-β signaling protein Smad2. J Neurosci 2013; 33:5138-51. [PMID: 23516280 DOI: 10.1523/jneurosci.5321-12.2013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
After CNS injury, axonal regeneration is limited by myelin-associated inhibitors; however, this can be overcome through elevation of intracellular cyclic AMP (cAMP), as occurs with conditioning lesions of the sciatic nerve. This study reports that expression of secretory leukocyte protease inhibitor (SLPI) is strongly upregulated in response to elevation of cAMP. We also show that SLPI can overcome inhibition by CNS myelin and significantly enhance regeneration of transected retinal ganglion cell axons in rats. Furthermore, regeneration of dorsal column axons does not occur after a conditioning lesion in SLPI null mutant mice, indicating that expression of SLPI is required for the conditioning lesion effect. Mechanistically, we demonstrate that SLPI localizes to the nuclei of neurons, binds to the Smad2 promoter, and reduces levels of Smad2 protein. Adenoviral overexpression of Smad2 also blocked SLPI-induced axonal regeneration. SLPI and Smad2 may therefore represent new targets for therapeutic intervention in CNS injury.
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144
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Mironova YA, Giger RJ. Where no synapses go: gatekeepers of circuit remodeling and synaptic strength. Trends Neurosci 2013; 36:363-73. [PMID: 23642707 DOI: 10.1016/j.tins.2013.04.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 04/01/2013] [Accepted: 04/01/2013] [Indexed: 02/07/2023]
Abstract
Growth inhibitory molecules in the adult mammalian central nervous system (CNS) have been implicated in the blocking of axonal sprouting and regeneration following injury. Prominent CNS regeneration inhibitors include Nogo-A, oligodendrocyte myelin glycoprotein (OMgp), and chondroitin sulfate proteoglycans (CSPGs), and a key question concerns their physiological role in the naïve CNS. Emerging evidence suggests novel functions in dendrites and at synapses of glutamatergic neurons. CNS regeneration inhibitors target the neuronal actin cytoskeleton to regulate dendritic spine maturation, long-term synapse stability, and Hebbian forms of synaptic plasticity. This is accomplished in part by antagonizing plasticity-promoting signaling pathways activated by neurotrophic factors. Altered function of CNS regeneration inhibitors is associated with mental illness and loss of long-lasting memory, suggesting unexpected and novel physiological roles for these molecules in brain health.
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Affiliation(s)
- Yevgeniya A Mironova
- Department of Cell and Developmental Biology, University of Michigan School of Medicine, 3065 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI 48109-2200, USA
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145
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Senescent-induced dysregulation of cAMP/CREB signaling and correlations with cognitive decline. Brain Res 2013; 1516:93-109. [PMID: 23623816 DOI: 10.1016/j.brainres.2013.04.033] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 04/12/2013] [Accepted: 04/13/2013] [Indexed: 11/20/2022]
Abstract
It is well known that alongside senescence there is a gradual decline in cognitive ability, most noticeably certain kinds of memory such as working, episodic, spatial, and long term memory. However, until recently, not much has been known regarding the specific mechanisms responsible for the decline in cognitive ability with age. Over the past decades, researchers have become more interested in cAMP signaling, and its downstream transcription factor cAMP response element binding protein (CREB) in the context of senescence. However, there is still a lack of understanding on what ultimately causes the cognitive deficits observed with senescence. This review will focus on the changes in intracellular signaling in the brain, more specifically, alterations in cAMP/CREB signaling in aging. In addition, the downstream effects of altered cAMP signaling on cognitive ability with age will be further discussed. Overall, understanding the senescent-related changes that occur in cAMP/CREB signaling could be important for the development of novel drug targets for both healthy aging, and pathological aging such as Alzheimer's disease.
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Costa LM, Pereira JE, Filipe VM, Magalhães LG, Couto PA, Gonzalo-Orden JM, Raimondo S, Geuna S, Maurício AC, Nikulina E, Filbin MT, Varejão AS. Rolipram promotes functional recovery after contusive thoracic spinal cord injury in rats. Behav Brain Res 2013; 243:66-73. [DOI: 10.1016/j.bbr.2012.12.056] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Revised: 12/24/2012] [Accepted: 12/29/2012] [Indexed: 01/28/2023]
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147
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Bell KFS, Bent RJ, Meese-Tamuri S, Ali A, Forder JP, Aarts MM. Calmodulin kinase IV-dependent CREB activation is required for neuroprotection via NMDA receptor-PSD95 disruption. J Neurochem 2013; 126:274-87. [PMID: 23363435 DOI: 10.1111/jnc.12176] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Revised: 01/20/2013] [Accepted: 01/21/2013] [Indexed: 02/04/2023]
Abstract
NMDA-type glutamate receptors mediate both trophic and excitotoxic signalling in CNS neurons. We have previously shown that blocking NMDAR- post-synaptic density-95 (PSD95) interactions provides significant protection from excitotoxicity and in vivo ischaemia; however, the mechanism of neuroprotection is unclear. Here, we report that blocking PSD-95 interactions with the Tat-NR2B9c peptide enhances a Ca²⁺-dependent protective pathway converging on cAMP Response Element binding protein (CREB) activation. We provide evidence that Tat-NR2B9c neuroprotection from oxygen glucose deprivation and NMDA toxicity occurs in parallel with the activation of calmodulin kinase signalling and is dependent on a sustained phosphorylation of the CREB transcription factor and its activator CaMKIV. Tat-NR2B9c-dependent neuroprotection and CREB phosphorylation are blocked by coapplication of CaM kinase (KN93 and STO-609) or CREB (KG-501) inhibitors, and by siRNA knockdown of CaMKIV. These results are mirrored in vivo in a rat model of permanent focal ischaemia. Tat-NR2B9c application significantly reduces infarct size and causes a selective and sustained elevation in CaMKIV phosphorylation; effects which are blocked by coadministration of KN93. Thus, calcium-dependent nuclear signalling via CaMKIV and CREB is critical for neuroprotection via NMDAR-PSD95 blockade, both in vitro and in vivo. This study highlights the importance of maintaining neuronal function following ischaemic injury. Future stroke research should target neurotrophic and pro-survival signal pathways in the development of novel neuroprotective strategies.
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Affiliation(s)
- Karen F S Bell
- Department of Biological Sciences, University of Toronto, Scarborough, Ontario, Canada
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148
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Quadrato G, Di Giovanni S. Waking up the sleepers: shared transcriptional pathways in axonal regeneration and neurogenesis. Cell Mol Life Sci 2013; 70:993-1007. [PMID: 22899311 PMCID: PMC11113138 DOI: 10.1007/s00018-012-1099-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Revised: 06/13/2012] [Accepted: 07/17/2012] [Indexed: 12/26/2022]
Abstract
In the last several years, relevant progress has been made in our understanding of the transcriptional machinery regulating CNS repair after acute injury, such as following trauma or stroke. In order to survive and functionally reconnect to the synaptic network, injured neurons activate an intrinsic rescue program aimed to increase their plasticity. Perhaps, in the attempt to switch back to a plastic and growth-competent state, post-mitotic neurons wake up and re-express a set of transcription factors that are also critical for the regulation of their younger brothers, the neural stem cells. Here, we review and discuss the transcriptional pathways regulating both axonal regeneration and neurogenesis highlighting the connection between the two. Clarification of their common molecular substrate may help simultaneous targeting of both neurogenesis and axonal regeneration with the hope to enhance functional recovery following CNS injury.
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Affiliation(s)
- Giorgia Quadrato
- Laboratory for NeuroRegeneration and Repair, Center for Neurology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Otfried-Mueller Strasse 27, 72076 Tuebingen, Germany
| | - Simone Di Giovanni
- Laboratory for NeuroRegeneration and Repair, Center for Neurology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Otfried-Mueller Strasse 27, 72076 Tuebingen, Germany
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149
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Figueroa JD, Cordero K, Llán MS, De Leon M. Dietary omega-3 polyunsaturated fatty acids improve the neurolipidome and restore the DHA status while promoting functional recovery after experimental spinal cord injury. J Neurotrauma 2013; 30:853-68. [PMID: 23294084 DOI: 10.1089/neu.2012.2718] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) confer multiple health benefits and decrease the risk of neurological disorders. Studies are needed, however, to identify promising cellular targets and to assess their prophylactic value against neurodegeneration. The present study (1) examined the efficacy of a preventive diet enriched with ω-3 PUFAs to reduce dysfunction in a well-established spinal cord injury (SCI) animal model and (2) used a novel metabolomics data analysis to identify potential neurolipidomic targets. Rats were fed with either control chow or chow enriched with ω-3 PUFAs (750 mg/kg/day) for 8 weeks before being subjected to a sham or a contusion SCI operation. We report new evidence showing that rats subjected to SCI after being pre-treated with a diet enriched with ω-3 PUFAs exhibit significantly better functional outcomes. Pre-treated animals exhibited lower sensory deficits, autonomic bladder recovery, and early improvements in locomotion that persisted for at least 8 weeks after trauma. We found that SCI triggers a robust alteration in the cord PUFA neurolipidome, which was characterized by a marked docosahexaenoic acid (DHA) deficiency. This DHA deficiency was associated with dysfunction and corrected with the ω-3 PUFA-enriched diet. Multivariate data analyses revealed that the spinal cord of animals consuming the ω-3 PUFA-enriched diet had a fundamentally distinct neurolipidome, particularly increasing the levels of essential and long chain ω-3 fatty acids and lysolipids at the expense of ω-6 fatty acids and its metabolites. Altogether, dietary ω-3 PUFAs prophylaxis confers resiliency to SCI mediated, at least in part, by generating a neuroprotective and restorative neurolipidome.
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Affiliation(s)
- Johnny D Figueroa
- Center for Health Disparities and Molecular Medicine and Departments of Basic Sciences and Pathology and Human Anatomy, Loma Linda University, Loma Linda, California, USA
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Quirié A, Demougeot C, Bertrand N, Mossiat C, Garnier P, Marie C, Prigent-Tessier A. Effect of stroke on arginase expression and localization in the rat brain. Eur J Neurosci 2013; 37:1193-202. [PMID: 23311438 DOI: 10.1111/ejn.12111] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 10/30/2012] [Accepted: 11/28/2012] [Indexed: 11/27/2022]
Abstract
Because arginase and nitric oxide (NO) synthases (NOS) compete to degrade l-arginine, arginase plays a crucial role in the modulation of NO production. Moreover, the arginase 1 isoform is a marker of M2 phenotype macrophages that play a key role in tissue remodeling and resolution of inflammation. While NO has been extensively investigated in ischemic stroke, the effect of stroke on the arginase pathway is unknown. The present study focuses on arginase expression/activity and localization before and after (1, 8, 15 and 30 days) the photothrombotic ischemic stroke model. This model results in a cortical lesion that reaches maximal volume at day 1 post-stroke and then decreases as a result of astrocytic scar formation. Before stroke, arginase 1 and 2 expressions were restricted to neurons. Stroke resulted in up-regulation of arginase 1 and increased arginase activity in the region centered on the lesion where inflammatory cells are present. These changes were associated with an early and long-lasting arginase 1 up-regulation in activated macrophages and astrocytes and a delayed arginase 1 down-regulation in neurons at the vicinity of the lesion. A linear positive correlation was observed between expressions of arginase 1 and glial fibrillary acidic protein as a marker of activated astrocytes. Moreover, the pattern of arginase 1 and brain-derived neurotrophic factor (BDNF) expressions in activated astrocytes was similar. Unlike arginase 1, arginase 2 expression was not changed by stroke. In conclusion, increased arginase 1 expression is not restricted to macrophages in inflammation elicited by stroke but also occurs in activated astrocytes where it may contribute to neuroplasticity through the control of BDNF production.
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Affiliation(s)
- Aurore Quirié
- Faculté de Pharmacie, Unité INSERM U1093 Cognition, Action et Plasticité Sensorimotrice, Dijon, France
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