501
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Wang Y, Schachner M. The intracellular domain of L1CAM binds to casein kinase 2α and is neuroprotective via inhibition of the tumor suppressors PTEN and p53. J Neurochem 2015; 133:828-43. [PMID: 25727698 DOI: 10.1111/jnc.13083] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 02/05/2015] [Accepted: 02/24/2015] [Indexed: 02/05/2023]
Abstract
Cell adhesion molecule L1 promotes neuritogenesis and neuronal survival through triggering MAPK pathways. Based on the findings that L1 is associated with casein kinase 2 (CK2), and that deficiency in PTEN promotes neuritogenesis in vitro and regeneration after trauma, we examined the functional relationship between L1 and PTEN. In parallel, we investigated the tumor suppressor p53, which also regulates neuritogenesis. Here, we report that the intracellular domain of L1 binds to the subunit CK2α, and that knockdown of L1 leads to CK2 dephosphorylation and an increase in PTEN and p53 levels. Overexpression of L1, but not the L1 mutants L1 (S1181N, E1184V), which reduced binding between L1 and CK2, reduced expression levels of PTEN and p53 proteins, and enhanced levels of phosphorylated CK2α and mammalian target of rapamycin, which is a downstream effector of PTEN and p53. Treatment of neurons with a CK2 inhibitor or transfection with CK2α siRNA increased levels of PTEN and p53, and inhibited neuritogenesis. The combined observations indicate that L1 downregulates expression of PTEN and p53 via direct binding to CK2α. We suggest that L1 stimulates neuritogenesis by activating CK2α leading to decreased levels of PTEN and p53 via a novel, L1-triggered and CK2α-mediated signal transduction pathway. L1CAM (L1 cell adhesion molecule) is implicated in neural functions through the cognate src/MAP kinase signaling pathway. We now describe a novel signaling platform operating via the alpha subunit of casein kinase 2 which binds to the intracellular domain of L1. Knockdown of L1CAM leads to increased levels of tumor suppressor PTEN (phosphatase and tensin homolog) and p53, known to inhibit neuritogenesis in vitro and recovery from trauma in vivo. By activating this enzyme, L1CAM adds to its beneficial functions by decreasing the levels of PTEN and p53.
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Affiliation(s)
- Yan Wang
- Center for Neuroscience, Shantou University Medical College, Shantou, Guangdong, China
| | - Melitta Schachner
- Center for Neuroscience, Shantou University Medical College, Shantou, Guangdong, China
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502
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Yang P, Qin Y, Bian C, Zhao Y, Zhang W. Intrathecal delivery of IL-6 reactivates the intrinsic growth capacity of pyramidal cells in the sensorimotor cortex after spinal cord injury. PLoS One 2015; 10:e0127772. [PMID: 25992975 PMCID: PMC4437647 DOI: 10.1371/journal.pone.0127772] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 04/20/2015] [Indexed: 01/23/2023] Open
Abstract
We have previously demonstrated the growth-promoting effect of intrathecal delivery of recombinant rat IL-6 immediately after corticospinal tract (CST) injury. Our present study aims to further clarify whether intrathecal delivery of IL-6 after CST injury could reactivate the intrinsic growth capacity of pyramidal cells in the sensorimotor cortex which project long axons to the spinal cord. We examined, by ELISA, levels of cyclic adenosine monophosphate (cAMP), adenylyl cyclase (AC, which synthesizes cAMP), phosphodiesterases (PDE, which degrades cAMP), and, by RT-PCR, the expression of regeneration-associated genes in the rat sensorimotor cortex after intrathecal delivery of IL-6 for 7 days, started immediately after CST injury. Furthermore, we injected retrograde neuronal tracer Fluorogold (FG) to the spinal cord to label pyramidal cells in the sensorimotor cortex, layers V and VI, combined with βIII-tubulin immunostaining, then we analyzed by immunohistochemisty and western blot the expression of the co-receptor gp-130 of IL-6 family, and pSTAT3 and mTOR, downstream IL-6/JAK/STAT3 and PI3K/AKT/mTOR signaling pathways respectively. We showed that intrathecal delivery of IL-6 elevated cAMP level and upregulated the expression of regeneration-associated genes including GAP-43, SPRR1A, CAP-23 and JUN-B, and the expression of pSTAT3 and mTOR in pyramidal cells of the sensorimotor cortex. In contrast, AG490, an inhibitor of JAK, partially blocked these effects of IL-6. All these results indicate that intrathecal delivery of IL-6 immediately after spinal cord injury can reactivate the intrinsic growth capacity of pyramidal cells in the sensorimotor cortex and these effects of IL-6 were partially JAK/STAT3-dependent.
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Affiliation(s)
- Ping Yang
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing, 400038, P.R China
- * E-mail:
| | - Yu Qin
- Cadet Brigade, Third Military Medical University, Chongqing, 400038, P.R China
| | - Chen Bian
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing, 400038, P.R China
| | - Yandong Zhao
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing, 400038, P.R China
| | - Wen Zhang
- Cadet Brigade, Third Military Medical University, Chongqing, 400038, P.R China
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503
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Tang P, Zhang Y, Chen C, Ji X, Ju F, Liu X, Gan WB, He Z, Zhang S, Li W, Zhang L. In vivo two-photon imaging of axonal dieback, blood flow, and calcium influx with methylprednisolone therapy after spinal cord injury. Sci Rep 2015; 5:9691. [PMID: 25989524 PMCID: PMC4437044 DOI: 10.1038/srep09691] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 03/17/2015] [Indexed: 12/30/2022] Open
Abstract
Severe spinal cord injury (SCI) can cause neurological dysfunction and paralysis. However, the early dynamic changes of neurons and their surrounding environment after SCI are poorly understood. Although methylprednisolone (MP) is currently the standard therapeutic agent for treating SCI, its efficacy remains controversial. The purpose of this project was to investigate the early dynamic changes and MP's efficacy on axonal damage, blood flow, and calcium influx into axons in a mouse SCI model. YFP H-line and Thy1-GCaMP transgenic mice were used in this study. Two-photon microscopy was used for imaging of axonal dieback, blood flow, and calcium influx post-injury. We found that MP treatment attenuated progressive damage of axons, increased blood flow, and reduced calcium influx post-injury. Furthermore, microglia/macrophages accumulated in the lesion site after SCI and expressed the proinflammatory mediators iNOS, MCP-1 and IL-1β. MP treatment markedly inhibited the accumulation of microglia/macrophages and reduced the expression of the proinflammatory mediators. MP treatment also improved the recovery of behavioral function post-injury. These findings suggest that MP exerts a neuroprotective effect on SCI treatment by attenuating progressive damage of axons, increasing blood flow, reducing calcium influx, and inhibiting the accumulation of microglia/macrophages after SCI.
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Affiliation(s)
- Peifu Tang
- Department of Orthopedics, the General Hospital of Chinese People's Liberation Army, Beijing, China, 100853
| | - Yiling Zhang
- 1] Department of Orthopedics, the General Hospital of Chinese People's Liberation Army, Beijing, China, 100853 [2] Key Laboratory of Chemical Genomics, Shenzhen Graduate School, Peking University, Shenzhen, China, 518055
| | - Chao Chen
- 1] Department of Orthopedics, the General Hospital of Chinese People's Liberation Army, Beijing, China, 100853 [2] Key Laboratory of Chemical Genomics, Shenzhen Graduate School, Peking University, Shenzhen, China, 518055
| | - Xinran Ji
- Department of Orthopedics, the General Hospital of Chinese People's Liberation Army, Beijing, China, 100853
| | - Furong Ju
- School of Life Sciences, Lanzhou University, Lanzhou, China, 73000
| | - Xingyu Liu
- Beijing YouAn Hospital, Capital Medical University, Beijing, China, 100069
| | - Wen-Biao Gan
- 1] Key Laboratory of Chemical Genomics, Shenzhen Graduate School, Peking University, Shenzhen, China, 518055 [2] Skirball Institute, Department of Neuroscience and Physiology, New York University School of Medicine, New York, USA, 10016
| | - Zhigang He
- F.M. Kirby Program in Neuroscience, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts, USA, 02115
| | - Shengxiang Zhang
- School of Life Sciences, Lanzhou University, Lanzhou, China, 73000
| | - Wei Li
- Key Laboratory of Chemical Genomics, Shenzhen Graduate School, Peking University, Shenzhen, China, 518055
| | - Lihai Zhang
- Department of Orthopedics, the General Hospital of Chinese People's Liberation Army, Beijing, China, 100853
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504
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The MDM4/MDM2-p53-IGF1 axis controls axonal regeneration, sprouting and functional recovery after CNS injury. Brain 2015; 138:1843-62. [DOI: 10.1093/brain/awv125] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/09/2015] [Indexed: 12/20/2022] Open
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505
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Song Y, Sretavan D, Salegio EA, Berg J, Huang X, Cheng T, Xiong X, Meltzer S, Han C, Nguyen TT, Bresnahan JC, Beattie MS, Jan LY, Jan YN. Regulation of axon regeneration by the RNA repair and splicing pathway. Nat Neurosci 2015; 18:817-25. [PMID: 25961792 PMCID: PMC4446171 DOI: 10.1038/nn.4019] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 04/07/2015] [Indexed: 12/15/2022]
Abstract
Mechanisms governing a neuron’s regenerative ability are important but not well understood. We identified Rtca, RNA 3′-terminal phosphate cyclase, as an inhibitor for axon regeneration. Removal of dRtca cell-autonomously enhanced axon regrowth in the Drosophila central nervous system, whereas its overexpression reduced axon regeneration in the periphery. Rtca along with the RNA ligase Rtcb and its catalyst Archease operate in the RNA repair/splicing pathway important for stress induced mRNA splicing, including that of Xbp1, a cellular stress sensor. dRtca and dArchease had opposing effects on Xbp1 splicing, and deficiency of dArchease or Xbp1 impeded axon regeneration in Drosophila. Moreover, overexpressing mammalian Rtca in cultured rodent neurons reduced axonal complexity in vitro, whereas reducing its function promoted retinal ganglion cell axon regeneration after optic nerve crush in mice. Our study thus links axon regeneration to cellular stress and RNA metabolism, revealing new potential therapeutic targets for treating nervous system trauma.
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Affiliation(s)
- Yuanquan Song
- 1] Howard Hughes Medical Institute, University of California, San Francisco, California, USA. [2] Department of Physiology, University of California, San Francisco, California, USA
| | - David Sretavan
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California, USA
| | - Ernesto A Salegio
- Brain and Spinal Injury Center, University of California, San Francisco, California, USA
| | - Jim Berg
- 1] Howard Hughes Medical Institute, University of California, San Francisco, California, USA. [2] Department of Physiology, University of California, San Francisco, California, USA
| | - Xi Huang
- 1] Howard Hughes Medical Institute, University of California, San Francisco, California, USA. [2] Department of Physiology, University of California, San Francisco, California, USA
| | - Tong Cheng
- 1] Howard Hughes Medical Institute, University of California, San Francisco, California, USA. [2] Department of Physiology, University of California, San Francisco, California, USA
| | - Xin Xiong
- Howard Hughes Medical Institute, University of California, San Francisco, California, USA
| | - Shan Meltzer
- 1] Howard Hughes Medical Institute, University of California, San Francisco, California, USA. [2] Department of Physiology, University of California, San Francisco, California, USA
| | - Chun Han
- 1] Howard Hughes Medical Institute, University of California, San Francisco, California, USA. [2] Department of Physiology, University of California, San Francisco, California, USA
| | - Trong-Tuong Nguyen
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California, USA
| | - Jacqueline C Bresnahan
- Brain and Spinal Injury Center, University of California, San Francisco, California, USA
| | - Michael S Beattie
- Brain and Spinal Injury Center, University of California, San Francisco, California, USA
| | - Lily Yeh Jan
- 1] Howard Hughes Medical Institute, University of California, San Francisco, California, USA. [2] Department of Physiology, University of California, San Francisco, California, USA
| | - Yuh Nung Jan
- 1] Howard Hughes Medical Institute, University of California, San Francisco, California, USA. [2] Department of Physiology, University of California, San Francisco, California, USA
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506
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Complement protein C1q modulates neurite outgrowth in vitro and spinal cord axon regeneration in vivo. J Neurosci 2015; 35:4332-49. [PMID: 25762679 DOI: 10.1523/jneurosci.4473-12.2015] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Traumatic injury to CNS fiber tracts is accompanied by failure of severed axons to regenerate and results in lifelong functional deficits. The inflammatory response to CNS trauma is mediated by a diverse set of cells and proteins with varied, overlapping, and opposing effects on histological and behavioral recovery. Importantly, the contribution of individual inflammatory complement proteins to spinal cord injury (SCI) pathology is not well understood. Although the presence of complement components increases after SCI in association with axons and myelin, it is unknown whether complement proteins affect axon growth or regeneration. We report a novel role for complement C1q in neurite outgrowth in vitro and axon regrowth after SCI. In culture, C1q increased neurite length on myelin. Protein and molecular assays revealed that C1q interacts directly with myelin associated glycoprotein (MAG) in myelin, resulting in reduced activation of growth inhibitory signaling in neurons. In agreement with a C1q-outgrowth-enhancing mechanism in which C1q binding to MAG reduces MAG signaling to neurons, complement C1q blocked both the growth inhibitory and repulsive turning effects of MAG in vitro. Furthermore, C1q KO mice demonstrated increased sensory axon turning within the spinal cord lesion after SCI with peripheral conditioning injury, consistent with C1q-mediated neutralization of MAG. Finally, we present data that extend the role for C1q in axon growth and guidance to include the sprouting patterns of descending corticospinal tract axons into spinal gray matter after dorsal column transection SCI.
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507
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Growth control mechanisms in neuronal regeneration. FEBS Lett 2015; 589:1669-77. [DOI: 10.1016/j.febslet.2015.04.046] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Revised: 04/20/2015] [Accepted: 04/21/2015] [Indexed: 11/19/2022]
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508
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Belin S, Nawabi H, Wang C, Tang S, Latremoliere A, Warren P, Schorle H, Uncu C, Woolf CJ, He Z, Steen JA. Injury-induced decline of intrinsic regenerative ability revealed by quantitative proteomics. Neuron 2015; 86:1000-1014. [PMID: 25937169 DOI: 10.1016/j.neuron.2015.03.060] [Citation(s) in RCA: 171] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 11/21/2014] [Accepted: 03/20/2015] [Indexed: 12/28/2022]
Abstract
Neurons differ in their responses to injury, but the underlying mechanisms remain poorly understood. Using quantitative proteomics, we characterized the injury-triggered response from purified intact and axotomized retinal ganglion cells (RGCs). Subsequent informatics analyses revealed a network of injury-response signaling hubs. In addition to confirming known players, such as mTOR, this also identified new candidates, such as c-myc, NFκB, and Huntingtin. Similar to mTOR, c-myc has been implicated as a key regulator of anabolic metabolism and is downregulated by axotomy. Forced expression of c-myc in RGCs, either before or after injury, promotes dramatic RGC survival and axon regeneration after optic nerve injury. Finally, in contrast to RGCs, neither c-myc nor mTOR was downregulated in injured peripheral sensory neurons. Our studies suggest that c-myc and other injury-responsive pathways are critical to the intrinsic regenerative mechanisms and might represent a novel target for developing neural repair strategies in adults.
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Affiliation(s)
- Stephane Belin
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Homaira Nawabi
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Chen Wang
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Shaojun Tang
- Department of Pathology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Alban Latremoliere
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Peter Warren
- Department of Urology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Hubert Schorle
- Department of Developmental Pathology, University of Bonn Medical School, Sigmund Freud Strasse 25, 53127 Bonn, Germany
| | - Ceren Uncu
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Clifford J Woolf
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Zhigang He
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
| | - Judith A Steen
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
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509
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Cui C, Xu G, Qiu J, Fan X. Up-regulation of miR-26a promotes neurite outgrowth and ameliorates apoptosis by inhibiting PTEN in bupivacaine injured mouse dorsal root ganglia. Cell Biol Int 2015; 39:933-42. [PMID: 25808510 DOI: 10.1002/cbin.10461] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 03/10/2015] [Indexed: 01/09/2023]
Affiliation(s)
- Changlei Cui
- Department of Anesthesiology; The First Hospital of Jilin University; Changchun JiLin Province 130021 China
| | - Gong Xu
- Department of Anesthesiology; The First Hospital of Jilin University; Changchun JiLin Province 130021 China
| | - Jinpeng Qiu
- Department of Anesthesiology; The First Hospital of Jilin University; Changchun JiLin Province 130021 China
| | - Xiushuang Fan
- Department of Anesthesiology; The First Hospital of Jilin University; Changchun JiLin Province 130021 China
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510
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Hu Y. The necessary role of mTORC1 in central nervous system axon regeneration. Neural Regen Res 2015; 10:186-8. [PMID: 25883608 PMCID: PMC4392657 DOI: 10.4103/1673-5374.152363] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2015] [Indexed: 02/05/2023] Open
Affiliation(s)
- Yang Hu
- Shriners Hospitals Pediatric Research Center, Center for Neural Repair and Rehabilitation, Temple University School of Medicine, Philadelphia, PA 19140-4106, USA
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511
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Ribas VT, Lingor P. Autophagy in degenerating axons following spinal cord injury: evidence for autophagosome biogenesis in retraction bulbs. Neural Regen Res 2015; 10:198-200. [PMID: 25883612 PMCID: PMC4392661 DOI: 10.4103/1673-5374.152367] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2015] [Indexed: 11/18/2022] Open
Affiliation(s)
- Vinicius T Ribas
- Department of Neurology, University Medicine Göttingen, 37075 Göttingen, Germany
| | - Paul Lingor
- Department of Neurology, University Medicine Göttingen, 37075 Göttingen, Germany ; Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
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512
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Overexpression of Sox11 promotes corticospinal tract regeneration after spinal injury while interfering with functional recovery. J Neurosci 2015; 35:3139-45. [PMID: 25698749 DOI: 10.1523/jneurosci.2832-14.2015] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Embryonic neurons, peripheral neurons, and CNS neurons in zebrafish respond to axon injury by initiating pro-regenerative transcriptional programs that enable axons to extend, locate appropriate targets, and ultimately contribute to behavioral recovery. In contrast, many long-distance projection neurons in the adult mammalian CNS, notably corticospinal tract (CST) neurons, display a much lower regenerative capacity. To promote CNS repair, a long-standing goal has been to activate pro-regenerative mechanisms that are normally missing from injured CNS neurons. Sox11 is a transcription factor whose expression is common to a many types of regenerating neurons, but it is unknown whether suboptimal Sox11 expression contributes to low regenerative capacity in the adult mammalian CNS. Here we show in adult mice that dorsal root ganglion neurons (DRGs) and CST neurons fail to upregulate Sox11 after spinal axon injury. Furthermore, forced viral expression of Sox11 reduces axonal dieback of DRG axons, and promotes CST sprouting and regenerative axon growth in both acute and chronic injury paradigms. In tests of forelimb dexterity, however, Sox11 overexpression in the cortex caused a modest but consistent behavioral impairment. These data identify Sox11 as a key transcription factor that can confer an elevated innate regenerative capacity to CNS neurons. The results also demonstrate an unexpected dissociation between axon growth and behavioral outcome, highlighting the need for additional strategies to optimize the functional output of stimulated neurons.
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513
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Plasticity of intact rubral projections mediates spontaneous recovery of function after corticospinal tract injury. J Neurosci 2015; 35:1443-57. [PMID: 25632122 DOI: 10.1523/jneurosci.3713-14.2015] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Axons in the adult CNS fail to regenerate after injury, and therefore recovery from spinal cord injury (SCI) is limited. Although full recovery is rare, a modest degree of spontaneous recovery is observed consistently in a broad range of clinical and nonclinical situations. To define the mechanisms mediating spontaneous recovery of function after incomplete SCI, we created bilaterally complete medullary corticospinal tract lesions in adult mice, eliminating a crucial pathway for voluntary skilled movement. Anatomic and pharmacogenetic tools were used to identify the pathways driving spontaneous functional recovery in wild-type and plasticity-sensitized mice lacking Nogo receptor 1. We found that plasticity-sensitized mice recovered 50% of normal skilled locomotor function within 5 weeks of lesion. This significant, yet incomplete, spontaneous recovery was accompanied by extensive sprouting of intact rubrofugal and rubrospinal projections with the emergence of a de novo circuit between the red nucleus and the nucleus raphe magnus. Transient silencing of this rubro-raphe circuit in vivo via activation of the inhibitory DREADD (designer receptor exclusively activated by designer drugs) receptor hM4di abrogated spontaneous functional recovery. These data highlight the pivotal role of uninjured motor circuit plasticity in supporting functional recovery after trauma, and support a focus of experimental strategies on enhancing intact circuit rearrangement to promote functional recovery after SCI.
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514
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Huang SY, Sung CS, Chen WF, Chen CH, Feng CW, Yang SN, Hung HC, Chen NF, Lin PR, Chen SC, Wang HMD, Chu TH, Tai MH, Wen ZH. Involvement of phosphatase and tensin homolog deleted from chromosome 10 in rodent model of neuropathic pain. J Neuroinflammation 2015; 12:59. [PMID: 25889774 PMCID: PMC4386079 DOI: 10.1186/s12974-015-0280-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 03/07/2015] [Indexed: 12/30/2022] Open
Abstract
Background Many cancer research studies have extensively examined the phosphatase and tensin homolog deleted from chromosome 10 (PTEN) pathway. There are only few reports that suggest that PTEN might affect pain; however, there is still a lack of evidence to show the role of PTEN for modulating pain. Here, we report a role for PTEN in a rodent model of neuropathic pain. Results We found that chronic constriction injury (CCI) surgery in rats could elicit downregulation of spinal PTEN as well as upregulation of phosphorylated PTEN (phospho-PTEN) and phosphorylated mammalian target of rapamycin (phospho-mTOR). After examining such changes in endogenous PTEN in neuropathic rats, we explored the effects of modulating the spinal PTEN pathway on nociceptive behaviors. The normal rats exhibited mechanical allodynia after intrathecal (i.t.) injection of adenovirus-mediated PTEN antisense oligonucleotide (Ad-antisense PTEN). These data indicate the importance of downregulation of spinal PTEN for nociception. Moreover, upregulation of spinal PTEN by i.t. adenovirus-mediated PTEN (Ad-PTEN) significantly prevented CCI-induced development of nociceptive sensitization, thermal hyperalgesia, mechanical allodynia, cold allodynia, and weight-bearing deficits in neuropathic rats. Furthermore, upregulation of spinal PTEN by i.t. Ad-PTEN significantly attenuated CCI-induced microglia and astrocyte activation, upregulation of tumor necrosis factor-α (TNF-α) and phospho-mTOR, and downregulation of PTEN in neuropathic rats 14 days post injury. Conclusions These findings demonstrate that PTEN plays a key, beneficial role in a rodent model of neuropathic pain.
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Affiliation(s)
- Shi-Ying Huang
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan. .,Center for Neuroscience, National Sun Yat-sen University, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan.
| | - Chun-Sung Sung
- Department of Anesthesiology, Taipei Veterans General Hospital, No. 201, Section 2, Shipai Road, Taipei, 11217, Taiwan. .,School of Medicine, National Yang-Ming University, No. 155, Section 2, Linong Street, Taipei, 11221, Taiwan.
| | - Wu-Fu Chen
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan. .,Department of Neurosurgery, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, No. 123, DAPI Road, Kaohsiung, 83301, Taiwan. .,Department of Neurosurgery, Xiamen Chang Gung Memorial Hospital, No. 123, Xiafei Road, Fujian, 361026, China.
| | - Chun-Hong Chen
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan. .,Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University and Academia Sinica, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan.
| | - Chien-Wei Feng
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan. .,Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University and Academia Sinica, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan.
| | - San-Nan Yang
- School of Medicine, College of Medicine and Department of Pediatrics, E-DA Hospital, I-Shou University, No. 1, Yida Road, Kaohsiung, 82445, Taiwan.
| | - Han-Chun Hung
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan. .,Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University and Academia Sinica, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan.
| | - Nan-Fu Chen
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan. .,Division of Neurosurgery, Department of Surgery, Kaohsiung Armed Forces General Hospital, No. 2, Zhongzheng 1st Road, Kaohsiung, 80284, Taiwan.
| | - Pey-Ru Lin
- Institute of Biomedical Sciences, National Sun Yat-sen University, #70 Lienhai Road, Kaohsiung, 80424, Taiwan.
| | - San-Cher Chen
- Center for Neuroscience, National Sun Yat-sen University, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan. .,Institute of Biomedical Sciences, National Sun Yat-sen University, #70 Lienhai Road, Kaohsiung, 80424, Taiwan.
| | - Hui-Min David Wang
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan. .,Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, No. 100, Shiquan 1st Road, Kaohsiung, 80708, Taiwan. .,Graduate Institute of Natural Products, Kaohsiung Medical University, No. 100, Shiquan 1st Road, Kaohsiung, 80708, Taiwan. .,Center for Stem Cell Research, Kaohsiung Medical University, No. 100, Shiquan 1st Road, Kaohsiung, 80708, Taiwan.
| | - Tian-Huei Chu
- Institute of Biomedical Sciences, National Sun Yat-sen University, #70 Lienhai Road, Kaohsiung, 80424, Taiwan.
| | - Ming-Hong Tai
- Center for Neuroscience, National Sun Yat-sen University, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan. .,Institute of Biomedical Sciences, National Sun Yat-sen University, #70 Lienhai Road, Kaohsiung, 80424, Taiwan. .,Department of Biological Sciences, National Sun Yat-sen University, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan.
| | - Zhi-Hong Wen
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan. .,Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University and Academia Sinica, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan. .,Marine Biomedical Laboratory and Center for Translational Biopharmaceuticals, Department of Marine Biotechnology and Resources, National Sun Yat-sen University, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan.
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515
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Wen J, Sun D, Tan J, Young W. A consistent, quantifiable, and graded rat lumbosacral spinal cord injury model. J Neurotrauma 2015; 32:875-92. [PMID: 25313633 PMCID: PMC4492780 DOI: 10.1089/neu.2013.3321] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The purpose of this study is to develop a rat lumbosacral spinal cord injury (SCI) model that causes consistent motoneuronal loss and behavior deficits. Most SCI models focus on the thoracic or cervical spinal cord. Lumbosacral SCI accounts for about one third of human SCI but no standardized lumbosacral model is available for evaluating therapies. Twenty-six adult female Sprague-Dawley rats were randomized to three groups: sham (n=9), 25 mm (n=8), and 50 mm (n=9). Sham rats had laminectomy only, while 25 mm and 50 mm rats were injured by dropping a 10 g rod from a height of 25 mm or 50 mm, respectively, onto the L4-5 spinal cord at the T13/L1 vertebral junction. We measured footprint length (FL), toe spreading (TS), intermediate toe spreading (ITS), and sciatic function index (SFI) from walking footprints, and static toe spreading (STS), static intermediate toe spreading (SITS), and static sciatic index (SSI) from standing footprints. At six weeks, we assessed neuronal and white matter loss, quantified axons, diameter, and myelin thickness in the peroneal and tibial nerves, and measured cross-sectional areas of tibialis anterior and gastrocnemius muscle fibers. The result shows that peroneal and tibial motoneurons were respectively distributed in 4.71 mm and 5.01 mm columns in the spinal cord. Dropping a 10-g weight from 25 mm or 50 mm caused 1.5 mm or 3.75 mm gaps in peroneal and tibial motoneuronal columns, respectively, and increased spinal cord white matter loss. Fifty millimeter contusions significantly increased FL and reduced TS, ITS, STS, SITS, SFI, and SSI more than 25 mm contusions, and resulted in smaller axon and myelinated axon diameters in tibial and peroneal nerves and greater atrophy of gastrocnemius and anterior tibialis muscles, than 25 mm contusions. This model of lumbosacral SCI produces consistent and graded loss of white matter, motoneuronal loss, peripheral nerve axonal changes, and anterior tibialis and gastrocnemius muscles atrophy in rats.
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Affiliation(s)
- Junxiang Wen
- 1 Department of Cell Biology and Neuroscience, Rutgers, the State University of New Jersey , Piscataway, New Jersey.,2 Department of Orthopaedics, Tongji University School of Medicine , Shanghai, China
| | - Dongming Sun
- 1 Department of Cell Biology and Neuroscience, Rutgers, the State University of New Jersey , Piscataway, New Jersey
| | - Jun Tan
- 2 Department of Orthopaedics, Tongji University School of Medicine , Shanghai, China
| | - Wise Young
- 1 Department of Cell Biology and Neuroscience, Rutgers, the State University of New Jersey , Piscataway, New Jersey
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516
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Ruschel J, Hellal F, Flynn KC, Dupraz S, Elliott DA, Tedeschi A, Bates M, Sliwinski C, Brook G, Dobrindt K, Peitz M, Brüstle O, Norenberg MD, Blesch A, Weidner N, Bunge MB, Bixby JL, Bradke F. Axonal regeneration. Systemic administration of epothilone B promotes axon regeneration after spinal cord injury. Science 2015; 348:347-52. [PMID: 25765066 DOI: 10.1126/science.aaa2958] [Citation(s) in RCA: 326] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 02/25/2015] [Indexed: 12/14/2022]
Abstract
After central nervous system (CNS) injury, inhibitory factors in the lesion scar and poor axon growth potential prevent axon regeneration. Microtubule stabilization reduces scarring and promotes axon growth. However, the cellular mechanisms of this dual effect remain unclear. Here, delayed systemic administration of a blood-brain barrier-permeable microtubule-stabilizing drug, epothilone B (epoB), decreased scarring after rodent spinal cord injury (SCI) by abrogating polarization and directed migration of scar-forming fibroblasts. Conversely, epothilone B reactivated neuronal polarization by inducing concerted microtubule polymerization into the axon tip, which propelled axon growth through an inhibitory environment. Together, these drug-elicited effects promoted axon regeneration and improved motor function after SCI. With recent clinical approval, epothilones hold promise for clinical use after CNS injury.
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Affiliation(s)
- Jörg Ruschel
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Farida Hellal
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Kevin C Flynn
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Sebastian Dupraz
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - David A Elliott
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Andrea Tedeschi
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Margaret Bates
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, 1095 Northwest 14th Terrace, Miami, FL33136, USA
| | - Christopher Sliwinski
- Spinal Cord Injury Center, Heidelberg University Hospital, Schlierbacher Landstr. 200A, 69118 Heidelberg, Germany
| | - Gary Brook
- Institute for Neuropathology, RWTH Aachen University, Steinbergweg 20, 52074, Aachen, Germany. Jülich-Aachen Research Alliance-Translational Brain Medicine
| | - Kristina Dobrindt
- Institute of Reconstructive Neurobiology, Life&Brain Center, University of Bonn and Hertie Foundation, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Michael Peitz
- Institute of Reconstructive Neurobiology, Life&Brain Center, University of Bonn and Hertie Foundation, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Oliver Brüstle
- Institute of Reconstructive Neurobiology, Life&Brain Center, University of Bonn and Hertie Foundation, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Michael D Norenberg
- Departments of Pathology, Biochemistry and Molecular Biology, University of Miami School of Medicine, Miami, FL 33101, USA
| | - Armin Blesch
- Spinal Cord Injury Center, Heidelberg University Hospital, Schlierbacher Landstr. 200A, 69118 Heidelberg, Germany
| | - Norbert Weidner
- Spinal Cord Injury Center, Heidelberg University Hospital, Schlierbacher Landstr. 200A, 69118 Heidelberg, Germany
| | - Mary Bartlett Bunge
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, 1095 Northwest 14th Terrace, Miami, FL33136, USA
| | - John L Bixby
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, 1095 Northwest 14th Terrace, Miami, FL33136, USA
| | - Frank Bradke
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany.
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517
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L-carnitine enhances axonal plasticity and improves white-matter lesions after chronic hypoperfusion in rat brain. J Cereb Blood Flow Metab 2015; 35:382-91. [PMID: 25465043 PMCID: PMC4348379 DOI: 10.1038/jcbfm.2014.210] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 10/28/2014] [Accepted: 10/30/2014] [Indexed: 12/28/2022]
Abstract
Chronic cerebral hypoperfusion causes white-matter lesions (WMLs) with oxidative stress and cognitive impairment. However, the biologic mechanisms that regulate axonal plasticity under chronic cerebral hypoperfusion have not been fully investigated. Here, we investigated whether L-carnitine, an antioxidant agent, enhances axonal plasticity and oligodendrocyte expression, and explored the signaling pathways that mediate axonal plasticity in a rat chronic hypoperfusion model. Adult male Wistar rats subjected to ligation of the bilateral common carotid arteries (LBCCA) were treated with or without L-carnitine. L-carnitine-treated rats exhibited significantly reduced escape latency in the Morris water maze task at 28 days after chronic hypoperfusion. Western blot analysis indicated that L-carnitine increased levels of phosphorylated high-molecular weight neurofilament (pNFH), concurrent with a reduction in phosphorylated phosphatase tensin homolog deleted on chromosome 10 (PTEN), and increased phosphorylated Akt and mammalian target of rapamycin (mTOR) at 28 days after chronic hypoperfusion. L-carnitine reduced lipid peroxidation and oxidative DNA damage, and enhanced oligodendrocyte marker expression and myelin sheath thickness after chronic hypoperfusion. L-carnitine regulates the PTEN/Akt/mTOR signaling pathway, and enhances axonal plasticity while concurrently ameliorating oxidative stress and increasing oligodendrocyte myelination of axons, thereby improving WMLs and cognitive impairment in a rat chronic hypoperfusion model.
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518
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Abstract
In recent years, several investigators have successfully regenerated axons in animal spinal cords without locomotor recovery. One explanation is that the animals were not trained to use the regenerated connections. Intensive locomotor training improves walking recovery after spinal cord injury (SCI) in people, and >90% of people with incomplete SCI recover walking with training. Although the optimal timing, duration, intensity, and type of locomotor training are still controversial, many investigators have reported beneficial effects of training on locomotor function. The mechanisms by which training improves recovery are not clear, but an attractive theory is available. In 1949, Donald Hebb proposed a famous rule that has been paraphrased as “neurons that fire together, wire together.” This rule provided a theoretical basis for a widely accepted theory that homosynaptic and heterosynaptic activity facilitate synaptic formation and consolidation. In addition, the lumbar spinal cord has a locomotor center, called the central pattern generator (CPG), which can be activated nonspecifically with electrical stimulation or neurotransmitters to produce walking. The CPG is an obvious target to reconnect after SCI. Stimulating motor cortex, spinal cord, or peripheral nerves can modulate lumbar spinal cord excitability. Motor cortex stimulation causes long-term changes in spinal reflexes and synapses, increases sprouting of the corticospinal tract, and restores skilled forelimb function in rats. Long used to treat chronic pain, motor cortex stimuli modify lumbar spinal network excitability and improve lower extremity motor scores in humans. Similarly, epidural spinal cord stimulation has long been used to treat pain and spasticity. Subthreshold epidural stimulation reduces the threshold for locomotor activity. In 2011, Harkema et al. reported lumbosacral epidural stimulation restores motor control in chronic motor complete patients. Peripheral nerve or functional electrical stimulation (FES) has long been used to activate sacral nerves to treat bladder and pelvic dysfunction and to augment motor function. In theory, FES should facilitate synaptic formation and motor recovery after regenerative therapies. Upcoming clinical trials provide unique opportunities to test the theory.
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Affiliation(s)
- Wise Young
- W. M. Keck Center for Collaborative Neuroscience, Rutgers, State University of New Jersey, Piscataway, NJ, USA
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519
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Danilov CA, Steward O. Conditional genetic deletion of PTEN after a spinal cord injury enhances regenerative growth of CST axons and motor function recovery in mice. Exp Neurol 2015; 266:147-60. [PMID: 25704959 DOI: 10.1016/j.expneurol.2015.02.012] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 02/02/2015] [Accepted: 02/06/2015] [Indexed: 12/30/2022]
Abstract
Previous studies indicate that conditional genetic deletion of phosphatase and tensin homolog (PTEN) in neonatal mice enhances the ability of axons to regenerate following spinal cord injury (SCI) in adults. Here, we assessed whether deleting PTEN in adult neurons post-SCI is also effective, and whether enhanced regenerative growth is accompanied by enhanced recovery of voluntary motor function. PTEN(loxP/loxP) mice received moderate contusion injuries at cervical level 5 (C5). One group received unilateral injections of adeno-associated virus expressing CRE (AAV-CRE) into the sensorimotor cortex; controls received a vector expressing green fluorescent protein (AAV-GFP) or injuries only (no vector injections). Forelimb function was tested for 14weeks post-SCI using a grip strength meter (GSM) and a hanging task. The corticospinal tract (CST) was traced by injecting mini-ruby BDA into the sensorimotor cortex. Forelimb gripping ability was severely impaired immediately post-SCI but recovered slowly over time. The extent of recovery was significantly greater in PTEN-deleted mice in comparison to either the AAV-GFP group or the injury only group. BDA tract tracing revealed significantly higher numbers of BDA-labeled axons in caudal segments in the PTEN-deleted group compared to control groups. In addition, in the PTEN-deleted group, there were exuberant collaterals extending from the main tract rostral to the lesion and into and around the scar tissue at the injury site. These results indicate that PTEN deletion in adult mice shortly post-SCI can enhance regenerative growth of CST axons and forelimb motor function recovery.
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Affiliation(s)
- Camelia A Danilov
- Reeve-Irvine Research Center, University of California, Irvine School of Medicine, Irvine, CA 92697, USA
| | - Oswald Steward
- Reeve-Irvine Research Center, University of California, Irvine School of Medicine, Irvine, CA 92697, USA; Department of Anatomy & Neurobiology, University of California, Irvine School of Medicine, Irvine, CA 92697, USA; Department of Neurobiology & Behavior, University of California, Irvine School of Medicine, Irvine, CA 92697, USA; Department of Neurosurgery, University of California Irvine, School of Medicine, Irvine, CA 92697, USA.
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520
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Quintá HR, Pasquini LA, Pasquini JM. Three-dimensional reconstruction of corticospinal tract using one-photon confocal microscopy acquisition allows detection of axonal disruption in spinal cord injury. J Neurochem 2015; 133:113-24. [DOI: 10.1111/jnc.13017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 12/02/2014] [Accepted: 12/03/2014] [Indexed: 12/25/2022]
Affiliation(s)
- Héctor R. Quintá
- Departamento de Química Biológica; Instituto de Química y Físico Química Biológica; Universidad de Buenos Aires; Buenos Aires Argentina
| | - Laura A. Pasquini
- Departamento de Química Biológica; Instituto de Química y Físico Química Biológica; Universidad de Buenos Aires; Buenos Aires Argentina
| | - Juana M. Pasquini
- Departamento de Química Biológica; Instituto de Química y Físico Química Biológica; Universidad de Buenos Aires; Buenos Aires Argentina
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521
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Mammalian target of rapamycin's distinct roles and effectiveness in promoting compensatory axonal sprouting in the injured CNS. J Neurosci 2015; 34:15347-55. [PMID: 25392502 DOI: 10.1523/jneurosci.1935-14.2014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mammalian target of rapamycin (mTOR) functions as a master sensor of nutrients and energy, and controls protein translation and cell growth. Deletion of phosphatase and tensin homolog (PTEN) in adult CNS neurons promotes regeneration of injured axons in an mTOR-dependent manner. However, others have demonstrated mTOR-independent axon regeneration in different cell types, raising the question of how broadly mTOR regulates axonal regrowth across different systems. Here we define the role of mTOR in promoting collateral sprouting of spared axons, a key axonal remodeling mechanism by which functions are recovered after CNS injury. Using pharmacological inhibition, we demonstrate that mTOR is dispensable for the robust spontaneous sprouting of corticospinal tract axons seen after pyramidotomy in postnatal mice. In contrast, moderate spontaneous axonal sprouting and induced-sprouting seen under different conditions in young adult mice (i.e., PTEN deletion or degradation of chondroitin proteoglycans; CSPGs) are both reduced upon mTOR inhibition. In addition, to further determine the potency of mTOR in promoting sprouting responses, we coinactivate PTEN and CSPGs, and demonstrate that this combination leads to an additive increase in axonal sprouting compared with single treatments. Our findings reveal a developmental switch in mTOR dependency for inducing axonal sprouting, and indicate that PTEN deletion in adult neurons neither recapitulates the regrowth program of postnatal animals, nor is sufficient to completely overcome an inhibitory environment. Accordingly, exploiting mTOR levels by targeting PTEN combined with CSPG degradation represents a promising strategy to promote extensive axonal plasticity in adult mammals.
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522
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Zou H, Ding Y, Wang K, Xiong E, Peng W, Du F, Zhang Z, Liu J, Gong A. MicroRNA-29A/PTEN pathway modulates neurite outgrowth in PC12 cells. Neuroscience 2015; 291:289-300. [PMID: 25665754 DOI: 10.1016/j.neuroscience.2015.01.055] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 12/30/2014] [Accepted: 01/23/2015] [Indexed: 02/01/2023]
Abstract
PTEN serves as an intrinsic brake on neurite outgrowth, but the regulatory mechanism that governs its action is not clear. In the present study, miR-29a was found to increase neurite outgrowth by decreasing PTEN expression. Results showed that miR-92a-1, miR-29a, miR-92b, and miR-29c expression levels increased during nerve growth factor (NGF)-induced differentiation of PC12 cells. Based on in silico analysis of possible miR-29a targets, PTEN mRNA may be a binding site for miR-29a. A protein expression assay and luciferase reporter assay showed that miR-29a could directly target the 3'-UTRs (untranslated regions) of PTEN mRNA and down-regulate the expression of PTEN. PC12 cells infected with lentiviral pLKO-miR-29a showed far higher levels of miR-29a and Akt phosphorylation level than those infected with control. This promoted neurite outgrowth of PC12 cells. Collectively, these results indicate that miR-29a is an important regulator of neurite outgrowth via targeting PTEN and that it may be a promising therapeutic target for neural disease.
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Affiliation(s)
- H Zou
- Department of Orthopedics, The Third Affiliated Hospital of Suzhou University, Changzhou 213003, China
| | - Y Ding
- Department of Orthopedics, The Third Affiliated Hospital of Suzhou University, Changzhou 213003, China
| | - K Wang
- Department of Orthopedics, The Third Affiliated Hospital of Suzhou University, Changzhou 213003, China
| | - E Xiong
- School of Medicine, Jiangsu University, Zhenjiang 212013, China
| | - W Peng
- School of Medicine, Jiangsu University, Zhenjiang 212013, China
| | - F Du
- School of Medicine, Jiangsu University, Zhenjiang 212013, China
| | - Z Zhang
- School of Medicine, Jiangsu University, Zhenjiang 212013, China
| | - J Liu
- Department of Orthopedics, The Third Affiliated Hospital of Suzhou University, Changzhou 213003, China.
| | - A Gong
- School of Medicine, Jiangsu University, Zhenjiang 212013, China.
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523
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Corticospinal sprouting differs according to spinal injury location and cortical origin in macaque monkeys. J Neurosci 2015; 34:12267-79. [PMID: 25209269 DOI: 10.1523/jneurosci.1593-14.2014] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The primate corticospinal tract (CST), the major descending pathway mediating voluntary hand movements, comprises nine or more functional subdivisions. The role of subcomponents other than that from primary motor cortex, however, is not well understood. We have previously shown that following a cervical dorsal rhizotomy (Darian-Smith et al., 2013), CST projections originating from primary somatosensory (S1) and motor (M1) cortex responded quite differently to injury. Terminal projections from the S1 (areas 3b/1/2) shrank to <60% of the contralateral side, while M1 CST projections remained robust or expanded (>110%). Here, we asked what happens when a central lesion is added to the equation, to better simulate clinical injury. Monkeys (n = 6) received either a unilateral (1) dorsal root lesion (DRL), (2) or a combined DRL/dorsal column lesion (DRL/DCL), or (3) a DRL/DCL where the DCL was made 4 months following the initial DRL. Electrophysiological recordings were made in S1 4 months postlesion in the first two groups, and 6 weeks after the DCL in the third lesion group, to identify the reorganized region of D1-D3 (thumb, index finger, and middle finger) representation. Anterograde tracers were then injected bilaterally to assess spinal terminal labeling. Remarkably, in all DRL/DCL animals, terminal projections from the S1 and M1 extended bilaterally and caudally well beyond terminal territories in normal animals or following a DRL. These data were highly significant. Extensive sprouting from the S1 CST has not been reported previously, and these data raise important questions about S1 CST involvement in recovery following spinal injury.
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524
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Abstract
Three theories of regeneration dominate neuroscience today, all purporting to explain why the adult central nervous system (CNS) cannot regenerate. One theory proposes that Nogo, a molecule expressed by myelin, prevents axonal growth. The second theory emphasizes the role of glial scars. The third theory proposes that chondroitin sulfate proteoglycans (CSPGs) prevent axon growth. Blockade of Nogo, CSPG, and their receptors indeed can stop axon growth in vitro and improve functional recovery in animal spinal cord injury (SCI) models. These therapies also increase sprouting of surviving axons and plasticity. However, many investigators have reported regenerating spinal tracts without eliminating Nogo, glial scar, or CSPG. For example, many motor and sensory axons grow spontaneously in contused spinal cords, crossing gliotic tissue and white matter surrounding the injury site. Sensory axons grow long distances in injured dorsal columns after peripheral nerve lesions. Cell transplants and treatments that increase cAMP and neurotrophins stimulate motor and sensory axons to cross glial scars and to grow long distances in white matter. Genetic studies deleting all members of the Nogo family and even the Nogo receptor do not always improve regeneration in mice. A recent study reported that suppressing the phosphatase and tensin homolog (PTEN) gene promotes prolific corticospinal tract regeneration. These findings cannot be explained by the current theories proposing that Nogo and glial scars prevent regeneration. Spinal axons clearly can and will grow through glial scars and Nogo-expressing tissue under some circumstances. The observation that deleting PTEN allows corticospinal tract regeneration indicates that the PTEN/AKT/mTOR pathway regulates axonal growth. Finally, many other factors stimulate spinal axonal growth, including conditioning lesions, cAMP, glycogen synthetase kinase inhibition, and neurotrophins. To explain these disparate regenerative phenomena, I propose that the spinal cord has evolved regenerative mechanisms that are normally suppressed by multiple extrinsic and intrinsic factors but can be activated by injury, mediated by the PTEN/AKT/mTOR, cAMP, and GSK3b pathways, to stimulate neural growth and proliferation.
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Affiliation(s)
- Wise Young
- W. M. Keck Center for Collaborative Neuroscience, Rutgers, State University of New Jersey, Piscataway, NJ, USA
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525
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Xu B, Park D, Ohtake Y, Li H, Hayat U, Liu J, Selzer ME, Longo FM, Li S. Role of CSPG receptor LAR phosphatase in restricting axon regeneration after CNS injury. Neurobiol Dis 2015; 73:36-48. [PMID: 25220840 PMCID: PMC4427014 DOI: 10.1016/j.nbd.2014.08.030] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 08/05/2014] [Accepted: 08/29/2014] [Indexed: 12/11/2022] Open
Abstract
Extracellular matrix molecule chondroitin sulfate proteoglycans (CSPGs) are highly upregulated in scar tissues and form a potent chemical barrier for CNS axon regeneration. Recent studies support that the receptor protein tyrosine phosphatase σ (PTPσ) and its subfamily member leukocyte common antigen related phosphatase (LAR) act as transmembrane receptors to mediate CSPG inhibition. PTPσ deficiency increased regrowth of ascending axons into scar tissues and descending corticospinal tract (CST) axons into the caudal spinal cord after spinal cord injury (SCI). Pharmacological LAR inhibition enhanced serotonergic axon growth in SCI mice. However, transgenic LAR deletion on axon growth in vivo and the role of LAR in regulating regrowth of other fiber tracts have not been studied. Here, we studied the role of LAR in restricting regrowth of injured descending CNS axons in deficient mice. LAR deletion increased regrowth of serotonergic axons into scar tissues and caudal spinal cord after dorsal over-hemitransection. LAR deletion also stimulated regrowth of CST fibers into the caudal spinal cord. LAR protein was upregulated days to weeks after injury and co-localized to serotonergic and CST axons. Moreover, LAR deletion improved functional recovery by increasing BMS locomotor scores and stride length and reducing grid walk errors. This is the first transgenic study that demonstrates the crucial role of LAR in restricting regrowth of injured CNS axons.
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Affiliation(s)
- Bin Xu
- Department of Neurosurgery, Affiliated Shanxi Dayi Hospital, Shanxi Academy of Medical Sciences, China; 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
| | - Dongsun Park
- 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
| | - Yosuke Ohtake
- 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
| | - Hui 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
| | - Umar Hayat
- 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
| | - Junjun Liu
- 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
| | - 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
| | - Frank M Longo
- Department of Neurology and Neurological Science, Stanford University, Stanford, CA 94305, 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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526
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Zhou H, Li X, Wu Q, Li F, Fu Z, Liu C, Liang Z, Chu T, Wang T, Lu L, Ning G, Kong X, Feng S. shRNA against PTEN promotes neurite outgrowth of cortical neurons and functional recovery in spinal cord contusion rats. Regen Med 2014; 10:411-29. [PMID: 25495396 DOI: 10.2217/rme.14.88] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
AIM To explore neurite growth/regeneration and spinal cord injury repair after PTEN silencing via lentivirus-mediated RNAi. MATERIALS & METHODS Cortical neurons were seeded on or adjacent to chondroitin sulfate proteoglycans. The length, number and crossing behavior of neurites were calculated. Lentivirus was locally injected into spinal cord contusion rats. The functional recovery and immunohistochemical staining were analyzed. RESULTS Neurites with PTEN silencing exhibited significant enhancements in elongation, initiation and crossing ability when they encountered chondroitin sulfate proteoglycans in vitro. In vivo PTEN silencing improved functional recovery significantly, and promoted axon and synapse formation, but not scar formation. CONCLUSIONS PTEN silencing may be promising for spinal cord injury repair.
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Affiliation(s)
- Hengxing Zhou
- 1Department of Orthopaedics, Tianjin Medical University General Hospital, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China
| | | | - Qiang Wu
- 3Department of Orthopaedics, First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, No. 314 Anshanxi Road, Nankai District, Tianjin 300193, PR China
| | - Fuyuan Li
- 1Department of Orthopaedics, Tianjin Medical University General Hospital, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China
| | | | - Chang Liu
- 4School of Medicine, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin 300071, PR China
| | - Zhipin Liang
- 4School of Medicine, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin 300071, PR China
| | - Tianci Chu
- 1Department of Orthopaedics, Tianjin Medical University General Hospital, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China
| | - Tianyi Wang
- 1Department of Orthopaedics, Tianjin Medical University General Hospital, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China
| | - Lu Lu
- 1Department of Orthopaedics, Tianjin Medical University General Hospital, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China
| | - Guangzhi Ning
- 1Department of Orthopaedics, Tianjin Medical University General Hospital, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China
| | - Xiaohong Kong
- 4School of Medicine, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin 300071, PR China
| | - Shiqing Feng
- 1Department of Orthopaedics, Tianjin Medical University General Hospital, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China
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527
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You say you want a revolution? CEREBRUM : THE DANA FORUM ON BRAIN SCIENCE 2014; 2014:17. [PMID: 26034524 PMCID: PMC4445585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
From their roles directing the W.M. Keck Center for Collaborative Neuroscience at Rutgers University, Wise Young and Patricia Morton have been on the front lines of spinal-cord-injury research for most of their careers. In this article they lean on lessons from the past, their own experience, and events still unfolding as they raise questions about the future of all scientific research.
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528
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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: 1.8] [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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529
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The mTORC1 effectors S6K1 and 4E-BP play different roles in CNS axon regeneration. Nat Commun 2014; 5:5416. [PMID: 25382660 PMCID: PMC4228696 DOI: 10.1038/ncomms6416] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 09/29/2014] [Indexed: 01/29/2023] Open
Abstract
Using mouse optic nerve (ON) crush as a CNS injury model, we and others have found that activation of the mammalian target of rapamycin complex 1 (mTORC1) in mature retinal ganglion cells by deletion of the negative regulators, phosphatase and tensin homolog (PTEN) and tuberous sclerosis 1, promotes ON regeneration. mTORC1 activation inhibits eukaryotic translation initiation factor 4E-binding protein (4E-BP) and activates ribosomal protein S6 kinase 1 (S6K1), both of which stimulate translation. We reasoned that mTORC1’s regeneration-promoting effects might be separable from its deleterious effects by differential manipulation of its downstream effectors. Here we show that S6K1 activation, but not 4E-BP inhibition, is sufficient to promote axon regeneration. However, inhibition of 4E-BP is required for PTEN deletion-induced axon regeneration. Both activation and inhibition of S6K1 decrease the effect of PTEN deletion on axon regeneration, implicating a dual role of S6K1 in regulating axon growth.
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530
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Ramer LM, Ramer MS, Bradbury EJ. Restoring function after spinal cord injury: towards clinical translation of experimental strategies. Lancet Neurol 2014; 13:1241-56. [PMID: 25453463 DOI: 10.1016/s1474-4422(14)70144-9] [Citation(s) in RCA: 196] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Spinal cord injury is currently incurable and treatment is limited to minimising secondary complications and maximising residual function by rehabilitation. Improved understanding of the pathophysiology of spinal cord injury and the factors that prevent nerve and tissue repair has fuelled a move towards more ambitious experimental treatments aimed at promoting neuroprotection, axonal regeneration, and neuroplasticity. By necessity, these new options are more invasive. However, in view of recent advances in spinal cord injury research and demand from patients, clinicians, and the scientific community to push promising experimental treatments to the clinic, momentum and optimism exist for the translation of candidate experimental treatments to clinical spinal cord injury. The ability to rescue, reactivate, and rewire spinal systems to restore function after spinal cord injury might soon be within reach.
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Affiliation(s)
- Leanne M Ramer
- King's College London, Regeneration Group, Wolfson Centre for Age-Related Diseases, Guy's Campus, London, UK; International Collaboration On Repair Discoveries, Blusson Spinal Cord Centre, Vancouver General Hospital, Vancouver, BC, Canada
| | - Matt S Ramer
- King's College London, Regeneration Group, Wolfson Centre for Age-Related Diseases, Guy's Campus, London, UK; International Collaboration On Repair Discoveries, Blusson Spinal Cord Centre, Vancouver General Hospital, Vancouver, BC, Canada; Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Elizabeth J Bradbury
- King's College London, Regeneration Group, Wolfson Centre for Age-Related Diseases, Guy's Campus, London, UK.
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531
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Esmaeili M, Berry M, Logan A, Ahmed Z. Decorin treatment of spinal cord injury. Neural Regen Res 2014; 9:1653-6. [PMID: 25374584 PMCID: PMC4211183 DOI: 10.4103/1673-5374.141797] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/18/2014] [Indexed: 12/23/2022] Open
Abstract
The scarring response after a penetrant central nervous system injury results from the interaction between invading leptominingeal/pericyte-derived fibroblasts and endogenous reactive astrocytes about the wound margin. Extracellular matrix and scar-derived axon growth inhibitory molecules fill the lesion site providing both a physical and chemical barrier to regenerating axons. Decorin, a small leucine-rich chondroitin-dermatan sulphate proteoglycan expressed by neurons and astrocytes in the central nervous system, is both anti-fibrotic and anti-inflammatory and attenuates the formation and partial dissolution of established and chronic scars. Here, we discuss the potential of using Decorin to antagonise scarring in the central nervous system.
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Affiliation(s)
- Maryam Esmaeili
- Neurotrauma Research Group, Neurobiology Section, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, B15 2TT, UK
| | - Martin Berry
- Neurotrauma Research Group, Neurobiology Section, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, B15 2TT, UK
| | - Ann Logan
- Neurotrauma Research Group, Neurobiology Section, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, B15 2TT, UK
| | - Zubair Ahmed
- Neurotrauma Research Group, Neurobiology Section, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, B15 2TT, UK
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532
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Ketschek A, Spillane M, Gallo G. Mechanism of NGF-induced formation of axonal filopodia. Commun Integr Biol 2014. [DOI: 10.4161/cib.13689] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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533
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PTEN depletion decreases disease severity and modestly prolongs survival in a mouse model of spinal muscular atrophy. Mol Ther 2014; 23:270-7. [PMID: 25369768 PMCID: PMC4445616 DOI: 10.1038/mt.2014.209] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 10/21/2014] [Indexed: 12/13/2022] Open
Abstract
Spinal muscular atrophy (SMA) is the second most common genetic cause of death in childhood. However, no effective treatment is available to halt disease progression. SMA is caused by mutations in the survival motor neuron 1 (SMN1) gene. We previously reported that PTEN depletion leads to an increase in survival of SMN-deficient motor neurons. Here, we aimed to establish the impact of PTEN modulation in an SMA mouse model in vivo. Initial experiments using intramuscular delivery of adeno-associated vector serotype 6 (AAV6) expressing shRNA against PTEN in an established mouse model of severe SMA (SMNΔ7) demonstrated the ability to ameliorate the severity of neuromuscular junction pathology. Subsequently, we developed self-complementary AAV9 expressing siPTEN (scAAV9-siPTEN) to allow evaluation of the effect of systemic suppression of PTEN on the disease course of SMA in vivo. Treatment with a single injection of scAAV9-siPTEN at postnatal day 1 resulted in a modest threefold extension of the lifespan of SMNΔ7 mice, increasing mean survival to 30 days, compared to 10 days in untreated mice. Our data revealed that systemic PTEN depletion is an important disease modifier in SMNΔ7 mice, and therapies aimed at lowering PTEN expression may therefore offer a potential therapeutic strategy for SMA.
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534
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Nielson JL, Haefeli J, Salegio EA, Liu AW, Guandique CF, Stück ED, Hawbecker S, Moseanko R, Strand SC, Zdunowski S, Brock JH, Roy RR, Rosenzweig ES, Nout-Lomas YS, Courtine G, Havton LA, Steward O, Reggie Edgerton V, Tuszynski MH, Beattie MS, Bresnahan JC, Ferguson AR. Leveraging biomedical informatics for assessing plasticity and repair in primate spinal cord injury. Brain Res 2014; 1619:124-38. [PMID: 25451131 DOI: 10.1016/j.brainres.2014.10.048] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 10/22/2014] [Accepted: 10/23/2014] [Indexed: 11/18/2022]
Abstract
Recent preclinical advances highlight the therapeutic potential of treatments aimed at boosting regeneration and plasticity of spinal circuitry damaged by spinal cord injury (SCI). With several promising candidates being considered for translation into clinical trials, the SCI community has called for a non-human primate model as a crucial validation step to test efficacy and validity of these therapies prior to human testing. The present paper reviews the previous and ongoing efforts of the California Spinal Cord Consortium (CSCC), a multidisciplinary team of experts from 5 University of California medical and research centers, to develop this crucial translational SCI model. We focus on the growing volumes of high resolution data collected by the CSCC, and our efforts to develop a biomedical informatics framework aimed at leveraging multidimensional data to monitor plasticity and repair targeting recovery of hand and arm function. Although the main focus of many researchers is the restoration of voluntary motor control, we also describe our ongoing efforts to add assessments of sensory function, including pain, vital signs during surgery, and recovery of bladder and bowel function. By pooling our multidimensional data resources and building a unified database infrastructure for this clinically relevant translational model of SCI, we are now in a unique position to test promising therapeutic strategies' efficacy on the entire syndrome of SCI. We review analyses highlighting the intersection between motor, sensory, autonomic and pathological contributions to the overall restoration of function. This article is part of a Special Issue entitled SI: Spinal cord injury.
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Affiliation(s)
- Jessica L Nielson
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California, San Francisco, CA (UCSF), United States
| | - Jenny Haefeli
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California, San Francisco, CA (UCSF), United States
| | - Ernesto A Salegio
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California, San Francisco, CA (UCSF), United States
| | - Aiwen W Liu
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California, San Francisco, CA (UCSF), United States
| | - Cristian F Guandique
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California, San Francisco, CA (UCSF), United States
| | - Ellen D Stück
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California, San Francisco, CA (UCSF), United States
| | - Stephanie Hawbecker
- California National Primate Research Center (CNPRC), University of California, Davis, CA (UCD), United States
| | - Rod Moseanko
- California National Primate Research Center (CNPRC), University of California, Davis, CA (UCD), United States
| | - Sarah C Strand
- California National Primate Research Center (CNPRC), University of California, Davis, CA (UCD), United States
| | - Sharon Zdunowski
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA (UCLA), United States
| | - John H Brock
- Center for Neural Repair, Department of Neurosciences, University of California, San Diego, La Jolla, CA (UCSD), United States
| | - Roland R Roy
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA (UCLA), United States
| | - Ephron S Rosenzweig
- Center for Neural Repair, Department of Neurosciences, University of California, San Diego, La Jolla, CA (UCSD), United States
| | - Yvette S Nout-Lomas
- Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, United States
| | - Gregoire Courtine
- Center for Neuroprosthetics and Brain Mind Institute, Swiss Federal Institute of Technology (EPFL), United States
| | - Leif A Havton
- Reeve-Irvine Research Center (RIRC), University of California, Irvine, CA (UCI), United States; Departments of Anesthesiology & Perioperative Care, Neurology, and Anatomy & Neurobiology, University of California, Irvine, CA, United States
| | - Oswald Steward
- Reeve-Irvine Research Center (RIRC), University of California, Irvine, CA (UCI), United States; Departments of Anatomy & Neurobiology, Neurobiology & Behavior, and Neurosurgery, University of California, Irvine, CA, United States
| | - V Reggie Edgerton
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA (UCLA), United States
| | - Mark H Tuszynski
- Departments of Anesthesiology & Perioperative Care, Neurology, and Anatomy & Neurobiology, University of California, Irvine, CA, United States; Veterans Administration Medical Center, La Jolla, CA, United States
| | - Michael S Beattie
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California, San Francisco, CA (UCSF), United States
| | - Jacqueline C Bresnahan
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California, San Francisco, CA (UCSF), United States
| | - Adam R Ferguson
- Brain and Spinal Injury Center (BASIC), Department of Neurological Surgery, University of California, San Francisco, CA (UCSF), United States.
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535
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Harvey AR, Lovett SJ, Majda BT, Yoon JH, Wheeler LPG, Hodgetts SI. Neurotrophic factors for spinal cord repair: Which, where, how and when to apply, and for what period of time? Brain Res 2014; 1619:36-71. [PMID: 25451132 DOI: 10.1016/j.brainres.2014.10.049] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 10/20/2014] [Accepted: 10/23/2014] [Indexed: 12/22/2022]
Abstract
A variety of neurotrophic factors have been used in attempts to improve morphological and behavioural outcomes after experimental spinal cord injury (SCI). Here we review many of these factors, their cellular targets, and their therapeutic impact on spinal cord repair in different, primarily rodent, models of SCI. A majority of studies report favourable outcomes but results are by no means consistent, thus a major aim of this review is to consider how best to apply neurotrophic factors after SCI to optimize their therapeutic potential. In addition to which factors are chosen, many variables need be considered when delivering trophic support, including where and when to apply a given factor or factors, how such factors are administered, at what dose, and for how long. Overall, the majority of studies have applied neurotrophic support in or close to the spinal cord lesion site, in the acute or sub-acute phase (0-14 days post-injury). Far fewer chronic SCI studies have been undertaken. In addition, comparatively fewer studies have administered neurotrophic factors directly to the cell bodies of injured neurons; yet in other instructive rodent models of CNS injury, for example optic nerve crush or transection, therapies are targeted directly at the injured neurons themselves, the retinal ganglion cells. The mode of delivery of neurotrophic factors is also an important variable, whether delivered by acute injection of recombinant proteins, sub-acute or chronic delivery using osmotic minipumps, cell-mediated delivery, delivery using polymer release vehicles or supporting bridges of some sort, or the use of gene therapy to modify neurons, glial cells or precursor/stem cells. Neurotrophic factors are often used in combination with cell or tissue grafts and/or other pharmacotherapeutic agents. Finally, the dose and time-course of delivery of trophic support should ideally be tailored to suit specific biological requirements, whether they relate to neuronal survival, axonal sparing/sprouting, or the long-distance regeneration of axons ending in a different mode of growth associated with terminal arborization and renewed synaptogenesis. This article is part of a Special Issue entitled SI: Spinal cord injury.
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Affiliation(s)
- Alan R Harvey
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
| | - Sarah J Lovett
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Bernadette T Majda
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Jun H Yoon
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Lachlan P G Wheeler
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Stuart I Hodgetts
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
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536
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Liang P, Liu J, Xiong J, Liu Q, Zhao J, Liang H, Zhao L, Tang H. Neural stem cell-conditioned medium protects neurons and promotes propriospinal neurons relay neural circuit reconnection after spinal cord injury. Cell Transplant 2014; 23 Suppl 1:S45-56. [PMID: 25333841 DOI: 10.3727/096368914x684989] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Human fetal neural stem cells (hNSCs) are used to treat a variety of neurological disorders involving spinal cord injury (SCI). Although their mechanism of action has been attributed to cell substitution, we examined the possibility that NSCs may have neuroprotective activities. The present article studied the action of hNSCs on protecting neurons and promoting corticospinal tract (CST) axon regeneration after SCI. hNSCs were isolated from the cortical tissue of spontaneously aborted human fetuses. The cells were removed from the NSC culture medium to acquire NSCM, thus excluding the effect of cell substitution. Continuous administration of the NSCM after the SCI resulted in extensive growth of the CST in the cervical region and more than tripled the formation of synaptic contacts between CST collaterals and propriospinal interneurons that project from the cervical level of the spinal cord to the lumbar level. NSCM reduced the number of caspase 3-positive apoptotic profiles at 7 days and protected against loss of the neurons 6 weeks after injury. NSCM promoted locomotor recovery with a five-point improvement on the BBB scale in adult rats. Thus, hNSCs help to set up a contour neural circuit via secretory factors, which may be the mechanism for their action in SCI rats. This manuscript is published as part of the International Association of Neurorestoratology (IANR) special issue of Cell Transplantation.
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Affiliation(s)
- Peng Liang
- Harbin Medical University Cancer Hospital, Harbin, China
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537
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Li S, He Q, Wang H, Tang X, Ho KW, Gao X, Zhang Q, Shen Y, Cheung A, Wong F, Wong YH, Ip NY, Jiang L, Yung WH, Liu K. Injured adult retinal axons with Pten and Socs3 co-deletion reform active synapses with suprachiasmatic neurons. Neurobiol Dis 2014; 73:366-76. [PMID: 25448764 DOI: 10.1016/j.nbd.2014.09.019] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 09/01/2014] [Accepted: 09/12/2014] [Indexed: 11/15/2022] Open
Abstract
Despite advances in promoting axonal regeneration after adult central nervous system injury, elicitation of a large number of lesion-passing axons reform active synaptic connections with natural target neurons remains limited. By deleting both Pten and Socs3 in retinal ganglion cells, we report that optic nerve axons after prechiasm lesion robustly reinnervate the hypothalamus, form new synapses with neurons in the suprachiasmatic nucleus (SCN), and re-integrate with the existing circuitry. Photic or electric stimulation of the retinal axons induces neuronal response in SCN. However both the innervation pattern and evoked responses are not completely restored by the regenerating axons, suggesting that combining with other strategies is necessary to overcome the defective rewiring. Our results support that boosting the intrinsic growth capacity in injured neurons promotes axonal reinnervation and rewiring.
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Affiliation(s)
- Songshan Li
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Center of Systems Biology and Human Health, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Qinghai He
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Center of Systems Biology and Human Health, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Hao Wang
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Xuming Tang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Center of Systems Biology and Human Health, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Kam Wing Ho
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Xin Gao
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Center of Systems Biology and Human Health, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Qian Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Center of Systems Biology and Human Health, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Yang Shen
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Center of Systems Biology and Human Health, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Annie Cheung
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Francis Wong
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Center of Systems Biology and Human Health, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Yung Hou Wong
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Nancy Y Ip
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Center of Systems Biology and Human Health, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Liwen Jiang
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Wing Ho Yung
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Kai Liu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Center of Systems Biology and Human Health, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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538
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Spinelli L, Lindsay YE, Leslie NR. PTEN inhibitors: an evaluation of current compounds. Adv Biol Regul 2014; 57:102-11. [PMID: 25446882 DOI: 10.1016/j.jbior.2014.09.012] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 09/06/2014] [Indexed: 12/22/2022]
Abstract
Small molecule inhibitors of many classes of enzymes, including phosphatases, have widespread use as experimental tools and as therapeutics. Efforts to develop inhibitors against the lipid phosphatase and tumour suppressor, PTEN, was for some time limited by concerns that their use as therapy could result in increased risk of cancer. However, the accumulation of evidence that short term PTEN inhibition may be valuable in conditions such as nerve injury has raised interest. Here we investigate the inhibition of PTEN by four available PTEN inhibitors, bpV(phen), bpV(pic), VO-OHpic and SF1670 and compared this inhibition with that of only 3 other related enzymes, the tyrosine phosphatase SHP1 and the phosphoinositide phosphatases INPP4A and INPP4B. Even with this very small number of comparators, for all compounds, inhibition of multiple enzymes was observed and with all three vanadate compounds, this was similar or more potent than the inhibition of PTEN. In particular, the bisperoxovanadate compounds were found to inhibit PTEN poorly in the presence of reducing agents including the cellular redox buffer glutathione.
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Affiliation(s)
- Laura Spinelli
- Institute of Biological Chemistry, Biophysics and Bioengineering, Nasmyth Building, Heriot Watt University, Edinburgh, EH14 4AS, UK; Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, UK
| | - Yvonne E Lindsay
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, UK
| | - Nicholas R Leslie
- Institute of Biological Chemistry, Biophysics and Bioengineering, Nasmyth Building, Heriot Watt University, Edinburgh, EH14 4AS, UK; Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, UK.
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539
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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: 3.2] [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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540
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Henley JM, Craig TJ, Wilkinson KA. Neuronal SUMOylation: mechanisms, physiology, and roles in neuronal dysfunction. Physiol Rev 2014; 94:1249-85. [PMID: 25287864 PMCID: PMC4187031 DOI: 10.1152/physrev.00008.2014] [Citation(s) in RCA: 135] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Protein SUMOylation is a critically important posttranslational protein modification that participates in nearly all aspects of cellular physiology. In the nearly 20 years since its discovery, SUMOylation has emerged as a major regulator of nuclear function, and more recently, it has become clear that SUMOylation has key roles in the regulation of protein trafficking and function outside of the nucleus. In neurons, SUMOylation participates in cellular processes ranging from neuronal differentiation and control of synapse formation to regulation of synaptic transmission and cell survival. It is a highly dynamic and usually transient modification that enhances or hinders interactions between proteins, and its consequences are extremely diverse. Hundreds of different proteins are SUMO substrates, and dysfunction of protein SUMOylation is implicated in a many different diseases. Here we briefly outline core aspects of the SUMO system and provide a detailed overview of the current understanding of the roles of SUMOylation in healthy and diseased neurons.
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Affiliation(s)
- Jeremy M Henley
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Tim J Craig
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Kevin A Wilkinson
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
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541
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AAVshRNA-mediated suppression of PTEN in adult rats in combination with salmon fibrin administration enables regenerative growth of corticospinal axons and enhances recovery of voluntary motor function after cervical spinal cord injury. J Neurosci 2014; 34:9951-62. [PMID: 25057197 DOI: 10.1523/jneurosci.1996-14.2014] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Conditional genetic deletion of phosphatase and tensin homolog (PTEN) in the sensorimotor cortex of neonatal mice enables regeneration of corticospinal tract (CST) axons after spinal cord injury (SCI). The present study addresses three questions: (1) whether PTEN knockdown in adult rats by nongenetic techniques enables CST regeneration, (2) whether interventions to enable CST regeneration enhance recovery of voluntary motor function, and (3) whether delivery of salmon fibrin into the injury site further enhances CST regeneration and motor recovery. Adult rats were trained in a staircase-reaching task and then received either intracortical injections of AAVshPTEN to delete PTEN or a control vector expressing shRNA for luciferase (AAVshLuc). Rats then received cervical dorsal hemisection injuries and salmon fibrin was injected into the injury site in half the rats, yielding four groups (AAVshPTEN, AAVshLuc, AAVshPTEN + fibrin, and AAVshLuc + fibrin). Forepaw function was assessed for 10 weeks after injury and CST axons were traced by injecting biotin-conjugated dextran amine into the sensorimotor cortex. Rats that received AAVshPTEN alone did not exhibit improved motor function, whereas rats that received AAVshPTEN and salmon fibrin had significantly higher forelimb-reaching scores. Tract tracing revealed that CST axons extended farther caudally in the group that received AAVshPTEN and salmon fibrin versus other groups. There were no significant differences in lesion size between the groups. Together, these data suggest that the combination of PTEN deletion and salmon fibrin injection into the lesion can significantly improve voluntary motor function after SCI by enabling regenerative growth of CST axons.
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542
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Chen M, Zheng B. Axon plasticity in the mammalian central nervous system after injury. Trends Neurosci 2014; 37:583-93. [PMID: 25218468 DOI: 10.1016/j.tins.2014.08.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 08/19/2014] [Accepted: 08/21/2014] [Indexed: 12/31/2022]
Abstract
It is widely recognized that severed axons in the adult central nervous system (CNS) have limited capacity to regenerate. However, mounting evidence from studies of CNS injury response and repair is challenging the prevalent view that the adult mammalian CNS is incapable of structural reorganization to adapt to an altered environment. Animal studies demonstrate the potential to achieve significant anatomical repair and functional recovery following CNS injury by manipulating axon growth regulators alone or in combination with activity-dependent strategies. With a growing understanding of the cellular and molecular mechanisms regulating axon plasticity, and the availability of new experimental tools to map detour circuits of functional importance, directing circuit rewiring to promote functional recovery may be achieved.
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Affiliation(s)
- Meifan Chen
- Department of Neurosciences, University of California, San Diego, 9500 Gilman Drive, MC 0691, La Jolla, CA 92093-0691, USA
| | - Binhai Zheng
- Department of Neurosciences, University of California, San Diego, 9500 Gilman Drive, MC 0691, La Jolla, CA 92093-0691, USA.
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543
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Dulin JN, Lu P. Bridging the injured spinal cord with neural stem cells. Neural Regen Res 2014; 9:229-31. [PMID: 25206804 PMCID: PMC4146155 DOI: 10.4103/1673-5374.128212] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2014] [Indexed: 12/19/2022] Open
Affiliation(s)
- Jennifer N Dulin
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Paul Lu
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA ; Veterans Administration Medical Center, San Diego, CA, 92161, USA
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544
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Lu P, Kadoya K, Tuszynski MH. Axonal growth and connectivity from neural stem cell grafts in models of spinal cord injury. Curr Opin Neurobiol 2014; 27:103-9. [DOI: 10.1016/j.conb.2014.03.010] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 03/12/2014] [Accepted: 03/14/2014] [Indexed: 02/06/2023]
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545
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Gobrecht P, Leibinger M, Andreadaki A, Fischer D. Sustained GSK3 activity markedly facilitates nerve regeneration. Nat Commun 2014; 5:4561. [PMID: 25078444 DOI: 10.1038/ncomms5561] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 06/30/2014] [Indexed: 12/16/2022] Open
Abstract
Promotion of axonal growth of injured DRG neurons improves the functional recovery associated with peripheral nerve regeneration. Both isoforms of glycogen synthase kinase 3 (GSK3; α and β) are phosphorylated and inactivated via phosphatidylinositide 3-kinase (PI3K)/AKT signalling upon sciatic nerve crush (SNC). However, the role of GSK3 phosphorylation in this context is highly controversial. Here we use knock-in mice expressing GSK3 isoforms resistant to inhibitory PI3K/AKT phosphorylation, and unexpectedly find markedly accelerated axon growth of DRG neurons in culture and in vivo after SNC compared with controls. Moreover, this enhanced regeneration strikingly accelerates functional recovery after SNC. These effects are GSK3 activity dependent and associated with elevated MAP1B phosphorylation. Altogether, our data suggest that PI3K/AKT-mediated inhibitory phosphorylation of GSK3 limits the regenerative outcome after peripheral nerve injury. Therefore, suppression of this internal 'regenerative break' may potentially provide a new perspective for the clinical treatment of nerve injuries.
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Affiliation(s)
- Philipp Gobrecht
- Division of Experimental Neurology, Department of Neurology, Heinrich Heine University of Düsseldorf, Merowingerplatz 1a, 40225 Düsseldorf, Germany
| | - Marco Leibinger
- Division of Experimental Neurology, Department of Neurology, Heinrich Heine University of Düsseldorf, Merowingerplatz 1a, 40225 Düsseldorf, Germany
| | - Anastasia Andreadaki
- Division of Experimental Neurology, Department of Neurology, Heinrich Heine University of Düsseldorf, Merowingerplatz 1a, 40225 Düsseldorf, Germany
| | - Dietmar Fischer
- Division of Experimental Neurology, Department of Neurology, Heinrich Heine University of Düsseldorf, Merowingerplatz 1a, 40225 Düsseldorf, Germany
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546
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Collyer E, Catenaccio A, Lemaitre D, Diaz P, Valenzuela V, Bronfman F, Court FA. Sprouting of axonal collaterals after spinal cord injury is prevented by delayed axonal degeneration. Exp Neurol 2014; 261:451-61. [PMID: 25079366 DOI: 10.1016/j.expneurol.2014.07.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 07/02/2014] [Accepted: 07/20/2014] [Indexed: 01/24/2023]
Abstract
After an incomplete spinal cord injury (SCI), partial recovery of locomotion is accomplished with time. Previous studies have established a functional link between extension of axon collaterals from spared spinal tracts and locomotor recovery after SCI, but the tissular signals triggering collateral sprouting have not been identified. Here, we investigated whether axonal degeneration after SCI contributes to the sprouting of collaterals from axons spared after injury. To this end, we evaluated collateral sprouting from BDA-labeled uninjured corticospinal axons after spinal cord hemisection (SCI(H)) in wild type (WT) mouse and Wld(S) mouse strains, which shows a significant delay in Wallerian degeneration after injury. After SCI(H), spared fibers of WT mice extend collateral sprouts to both intact and denervated sides of the spinal cord distant from the injury site. On the contrary, in the Wld(S) mice collateral sprouting from spared fibers was greatly reduced after SCI(H). Consistent with a role for collateral sprouting in functional recovery after SCI, locomotor recovery after SCI(H) was impaired in Wld(S) mice compared to WT animals. In conclusion, our results identify axonal degeneration as one of the triggers for collateral sprouting from the contralesional uninjured fibers after an SCI(H). These results open the path for identifying molecular signals associated with tissular changes after SCI that promotes collateral sprouting and functional recovery.
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Affiliation(s)
- E Collyer
- Millenium Nucleus for Regenerative Biology, Faculty of Biology, Pontificia Universidad Catolica de Chile, Santiago, Chile.
| | - A Catenaccio
- Millenium Nucleus for Regenerative Biology, Faculty of Biology, Pontificia Universidad Catolica de Chile, Santiago, Chile.
| | - D Lemaitre
- Millenium Nucleus for Regenerative Biology, Faculty of Biology, Pontificia Universidad Catolica de Chile, Santiago, Chile.
| | - P Diaz
- Millenium Nucleus for Regenerative Biology, Faculty of Biology, Pontificia Universidad Catolica de Chile, Santiago, Chile.
| | - V Valenzuela
- Millenium Nucleus for Regenerative Biology, Faculty of Biology, Pontificia Universidad Catolica de Chile, Santiago, Chile.
| | - F Bronfman
- Millenium Nucleus for Regenerative Biology, Faculty of Biology, Pontificia Universidad Catolica de Chile, Santiago, Chile.
| | - F A Court
- Millenium Nucleus for Regenerative Biology, Faculty of Biology, Pontificia Universidad Catolica de Chile, Santiago, Chile; Neurounion Biomedical Foundation, Santiago, Chile.
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547
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Wu Z, Zhao Z, Yu Y, Hu X, Xu W, Zeng Z, Sun YE, Cheng L. New strategies for the repair of spinal cord injury. CHINESE SCIENCE BULLETIN-CHINESE 2014. [DOI: 10.1007/s11434-014-0484-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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548
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Abstract
Eye injuries are common in warfare with an incidence of approximately 10%. They carry a high morbidity, as they can determine an injured person’s future independence and employability. The majority are a combination of primary and secondary blast mechanisms, though tertiary and quaternary types are common. There is some evidence of quinary types from toxic elements from the explosion. Eye protection significantly reduces the incidence and severity of ballistic eye injury but does not eliminate it. Thermal ocular burns are relatively common in warfare. The treatment goal is to minimise limbal stem cell damage. Human amniotic membrane can be used to promote this. Retinal and optic nerve injury following closed eye trauma are currently untreatable, but neuroprotective and neuroregenerative agents are being developed to improve outcomes. Sensory substitution of the sense of touch for sight can help orientate blinded individual in their surroundings. Ophthalmology has a major impact on the lives of the war wounded.
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Affiliation(s)
- Robert AH Scott
- Royal Centre for Defence Medicine, New Queen Elizabeth Hospital, Birmingham, UK
- Section of Neurotrauma and Neurodegeneration, School of Clinical and Experimental Medicine, University of Birmingham, UK
- Birmingham and Midland Eye Centre, Birmingham, UK
| | - Richard J Blanch
- Royal Centre for Defence Medicine, New Queen Elizabeth Hospital, Birmingham, UK
- Section of Neurotrauma and Neurodegeneration, School of Clinical and Experimental Medicine, University of Birmingham, UK
| | - Peter J Morgan-Warren
- Royal Centre for Defence Medicine, New Queen Elizabeth Hospital, Birmingham, UK
- Section of Neurotrauma and Neurodegeneration, School of Clinical and Experimental Medicine, University of Birmingham, UK
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549
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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: 138] [Impact Index Per Article: 13.8] [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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550
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Li Y, Alam M, Guo S, Ting KH, He J. Electronic bypass of spinal lesions: activation of lower motor neurons directly driven by cortical neural signals. J Neuroeng Rehabil 2014; 11:107. [PMID: 24990580 PMCID: PMC4094416 DOI: 10.1186/1743-0003-11-107] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 06/20/2014] [Indexed: 01/08/2023] Open
Abstract
Background Lower motor neurons in the spinal cord lose supraspinal inputs after complete spinal cord injury, leading to a loss of volitional control below the injury site. Extensive locomotor training with spinal cord stimulation can restore locomotion function after spinal cord injury in humans and animals. However, this locomotion is non-voluntary, meaning that subjects cannot control stimulation via their natural “intent”. A recent study demonstrated an advanced system that triggers a stimulator using forelimb stepping electromyographic patterns to restore quadrupedal walking in rats with spinal cord transection. However, this indirect source of “intent” may mean that other non-stepping forelimb activities may false-trigger the spinal stimulator and thus produce unwanted hindlimb movements. Methods We hypothesized that there are distinguishable neural activities in the primary motor cortex during treadmill walking, even after low-thoracic spinal transection in adult guinea pigs. We developed an electronic spinal bridge, called “Motolink”, which detects these neural patterns and triggers a “spinal” stimulator for hindlimb movement. This hardware can be head-mounted or carried in a backpack. Neural data were processed in real-time and transmitted to a computer for analysis by an embedded processor. Off-line neural spike analysis was conducted to calculate and preset the spike threshold for “Motolink” hardware. Results We identified correlated activities of primary motor cortex neurons during treadmill walking of guinea pigs with spinal cord transection. These neural activities were used to predict the kinematic states of the animals. The appropriate selection of spike threshold value enabled the “Motolink” system to detect the neural “intent” of walking, which triggered electrical stimulation of the spinal cord and induced stepping-like hindlimb movements. Conclusion We present a direct cortical “intent”-driven electronic spinal bridge to restore hindlimb locomotion after complete spinal cord injury.
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Affiliation(s)
| | | | | | | | - Jufang He
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
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