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Hu J, Zhang G, Rodemer W, Jin LQ, Selzer ME. Combined RhoA morpholino and ChABC treatment protects identified lamprey neurons from retrograde apoptosis after spinal cord injury. Front Cell Neurosci 2023; 17:1292012. [PMID: 38179205 PMCID: PMC10764559 DOI: 10.3389/fncel.2023.1292012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Accepted: 11/15/2023] [Indexed: 01/06/2024] Open
Abstract
Previously, we reported that RhoA knockdown by morpholino antisense oligonucleotides (MOs), and enzymatic digestion of chondroitin sulfate proteoglycans (CSPGs) at the site of injury with chondroitinase ABC (ChABC), each can reduce retrograde neuronal apoptosis after spinal cord transection in the lamprey. To elucidate the mechanisms in neuronal survival and axon regeneration, we have investigated whether these two effects are additive in vivo. We used lampreys as a spinal cord injury model. MOs were used to knockdown RhoA and Chondroitinase ABC (ChABC) was used to digest CSPGs in vivo. Retrograde labeling, fluorochrome-labeled inhibitor of caspase activity (FLICA), immunohistochemistry, and western blots were performed to assess axonal regeneration, neuronal apoptotic signaling and Akt activation. Four treatment combinations were evaluated at 2-, 4-, and 10-weeks post-transection: (1) Control MO plus enzyme buffer (Ctrl); (2) control MO plus ChABC; (3) RhoA MO plus enzyme buffer (RhoA MO); and (4) RhoA MO plus ChABC (RhoA MO + ChABC). Consistent with our previous findings, at 4-weeks post-transection, there was less caspase activation in the ChABC and RhoA MO groups than in the Ctrl group. Moreover, the RhoA MO plus ChABC group had the best protective effect on identified reticulospinal (RS) neurons among the four treatment combinations. At 2 weeks post-transection, when axons have retracted maximally in the rostral stump and are beginning to regenerate back toward the lesion, the axon tips in the three treatment groups each were closer to the transection than those in the Ctr MO plus enzyme buffer group. Long-term axon regeneration also was evaluated for the large, individually identified RS neurons at 10 weeks post-transection by retrograde labeling. The percent regenerated axons in the RhoA MO plus ChABC group was greater than that in any of the other groups. Akt phosphorylation levels at threonine 308 was quantified in the identified RS neurons by western blots and immunofluorescence. The RhoA MO plus ChABC treatment enhanced pAkt-308 phosphorylation more than any of the other treatment groups. Although some of the effects of CSPGs are mediated through RhoA activation, some growth-inhibiting mechanisms of RhoA and CSPGs are independent of each other, so combinatorial therapies may be warranted.
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Affiliation(s)
- Jianli Hu
- Center for Neural Repair and Rehabilitation (Shriners Hospitals Pediatric Research Center), Lewis Katz School of Medicine (LKSOM) at Temple University, Philadelphia, PA, United States
- Department of Neural Sciences, LKSOM, Philadelphia, PA, United States
| | - Guixin Zhang
- Center for Neural Repair and Rehabilitation (Shriners Hospitals Pediatric Research Center), Lewis Katz School of Medicine (LKSOM) at Temple University, Philadelphia, PA, United States
- Department of Neural Sciences, LKSOM, Philadelphia, PA, United States
| | - William Rodemer
- Center for Neurodegenerative Disease Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Li-Qing Jin
- Center for Neural Repair and Rehabilitation (Shriners Hospitals Pediatric Research Center), Lewis Katz School of Medicine (LKSOM) at Temple University, Philadelphia, PA, United States
- Department of Neural Sciences, LKSOM, Philadelphia, PA, United States
| | - Michael E. Selzer
- Center for Neural Repair and Rehabilitation (Shriners Hospitals Pediatric Research Center), Lewis Katz School of Medicine (LKSOM) at Temple University, Philadelphia, PA, United States
- Department of Neural Sciences, LKSOM, Philadelphia, PA, United States
- Department of Neurology, LKSOM, Philadelphia, PA, United States
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Song J, Wang J. SIRT3 regulates bronchial epithelium apoptosis and aggravates airway inflammation in asthma. Mol Med Rep 2022; 25:144. [PMID: 35234263 PMCID: PMC8915391 DOI: 10.3892/mmr.2022.12660] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 10/20/2021] [Indexed: 11/06/2022] Open
Affiliation(s)
- Jie Song
- Department of Pulmonary and Critical Care Medicine, Beijing Luhe Hospital, Capital Medical University, Tongzhou, Beijing 101100, P.R. China
| | - Jinxiang Wang
- Department of Pulmonary and Critical Care Medicine, Beijing Luhe Hospital, Capital Medical University, Tongzhou, Beijing 101100, P.R. China
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Khodabandeh Z, Mehrabani D, Dehghani F, Gashmardi N, Erfanizadeh M, Zare S, Bozorg-Ghalati F. Spinal cord injury repair using mesenchymal stem cells derived from bone marrow in mice: A stereological study. Acta Histochem 2021; 123:151720. [PMID: 34083065 DOI: 10.1016/j.acthis.2021.151720] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 05/02/2021] [Accepted: 05/04/2021] [Indexed: 12/13/2022]
Abstract
Transplantation of bone marrow stem cells (BMSCs) has shown to have a vital role in promoting nerve regeneration after SCI. The aim of this study was to investigate the effect of BMSCs transplantation in healing of spinal cord injury (SCI) in mice based on morphologic parameters. Forty two male mice were randomly divided into 3 groups of control with no intervention, experimental SCI without treatment, and experimental SCI transplanted with 2 × 105 BMSCs intravenously. To induce SCI bilaterally, T10 was compressed for 2 min. The animals were sacrificed 3 and 5 weeks after SCI and T7-T11 segments of spinal cord were removed and stained by Giemsa and H&E methods. Stereological assessment estimated the gray and white matter volume, the number of neurons and neuroglia and diameter of central canal. The average amount of gray matter in SCI injury group was significantly lower than control group. An increase in the number of neurons was noted after cell transplantation. The number of neurons in SCI injury group significantly decreased in comparison to the control group. In cell transplantation group, a significant increase in the number of neurons was visible when compared to SCI injury group. The increase in the number of neurons after cell transplantation denotes to the regenerative potential of BMSCs in SCI. These findings can be added to the literature and open a new window when targeting treatment of SCI.
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Affiliation(s)
- Zahra Khodabandeh
- Stem cells Technology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Davood Mehrabani
- Burn and Wound Healing Research Center, Shiraz University of Medical Sciences, Shiraz, Iran; Comparative and Experimental Medicine Center, Shiraz University of Medical Sciences, Shiraz, Iran; Li Ka Shing Center for Health Research and Innovation, University of Alberta, Edmonton, AB, Canada.
| | - Farzaneh Dehghani
- Department of Anatomical Sciences, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
| | | | - Mahboobeh Erfanizadeh
- Department of Anatomical Sciences, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Shahrokh Zare
- Stem cells Technology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Farzaneh Bozorg-Ghalati
- Department of Molecular Medicine, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran
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Hu J, Rodemer W, Zhang G, Jin LQ, Li S, Selzer ME. Chondroitinase ABC Promotes Axon Regeneration and Reduces Retrograde Apoptosis Signaling in Lamprey. Front Cell Dev Biol 2021; 9:653638. [PMID: 33842481 PMCID: PMC8027354 DOI: 10.3389/fcell.2021.653638] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 02/26/2021] [Indexed: 12/22/2022] Open
Abstract
Paralysis following spinal cord injury (SCI) is due to failure of axonal regeneration. It is believed that axon growth is inhibited by the presence of several types of inhibitory molecules in central nervous system (CNS), including the chondroitin sulfate proteoglycans (CSPGs). Many studies have shown that digestion of CSPGs with chondroitinase ABC (ChABC) can enhance axon growth and functional recovery after SCI. However, due to the complexity of the mammalian CNS, it is still unclear whether this involves true regeneration or only collateral sprouting by uninjured axons, whether it affects the expression of CSPG receptors such as protein tyrosine phosphatase sigma (PTPσ), and whether it influences retrograde neuronal apoptosis after SCI. In the present study, we assessed the roles of CSPGs in the regeneration of spinal-projecting axons from brainstem neurons, and in the process of retrograde neuronal apoptosis. Using the fluorochrome-labeled inhibitor of caspase activity (FLICA) method, apoptotic signaling was seen primarily in those large, individually identified reticulospinal (RS) neurons that are known to be “bad-regenerators.” Compared to uninjured controls, the number of all RS neurons showing polycaspase activity increased significantly at 2, 4, 8, and 11 weeks post-transection (post-TX). ChABC application to a fresh TX site reduced the number of polycaspase-positive RS neurons at 2 and 11 weeks post-TX, and also reduced the number of active caspase 3-positive RS neurons at 4 weeks post-TX, which confirmed the beneficial role of ChABC treatment in retrograde apoptotic signaling. ChABC treatment also greatly promoted axonal regeneration at 10 weeks post-TX. Correspondingly, PTPσ mRNA expression was reduced in the perikaryon. Previously, PTPσ mRNA expression was shown to correlate with neuronal apoptotic signaling at 2 and 10 weeks post-TX. In the present study, this correlation persisted after ChABC treatment, which suggests that PTPσ may be involved more generally in signaling axotomy-induced retrograde neuronal apoptosis. Moreover, ChABC treatment caused Akt activation (pAkt-308) to be greatly enhanced in brain post-TX, which was further confirmed in individually identified RS neurons. Thus, CSPG digestion not only enhances axon regeneration after SCI, but also inhibits retrograde RS neuronal apoptosis signaling, possibly by reducing PTPσ expression and enhancing Akt activation.
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Affiliation(s)
- Jianli Hu
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
| | - William Rodemer
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
| | - Guixin Zhang
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
| | - Li-Qing Jin
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
| | - Shuxin Li
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States.,Department of Anatomy and Cell Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
| | - Michael E Selzer
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States.,Department of Neurology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
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Zhang G, Rodemer W, Sinitsa I, Hu J, Selzer ME. Source of Early Regenerating Axons in Lamprey Spinal Cord Revealed by Wholemount Optical Clearing with BABB. Cells 2020; 9:cells9112427. [PMID: 33172031 PMCID: PMC7694618 DOI: 10.3390/cells9112427] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 11/04/2020] [Accepted: 11/04/2020] [Indexed: 12/22/2022] Open
Abstract
Many studies of axon regeneration in the lamprey focus on 18 pairs of large identified reticulospinal (RS) neurons, whose regenerative abilities have been individually quantified. Their axons retract during the first 2 weeks after transection (TX), and many grow back to the site of injury by 4 weeks. However, locomotor movements begin before 4 weeks and the lesion is invaded by axons as early as 2 weeks post-TX. The origins of these early regenerating axons are unknown. Their identification could be facilitated by studies in central nervous system (CNS) wholemounts, particularly if spatial resolution and examination by confocal microscopy were not limited by light scattering. We have used benzyl alcohol/benzyl benzoate (BABB) clearing to enhance the resolution of neuronal perikarya and regenerated axons by confocal microscopy in lamprey CNS wholemounts, and to assess axon regeneration by retrograde and anterograde labeling with fluorescent dye applied to a second TX caudal or rostral to the original lesion, respectively. We found that over 50% of the early regenerating axons belonged to small neurons in the brainstem. Some propriospinal neurons located close to the TX also contributed to early regeneration. The number of early regenerating propriospinal neurons decreased with distance from the original lesion. Descending axons from the brainstem were labeled anterogradely by application of tracer to a second TX close to the spinal-medullary junction. This limited contamination of the data by regenerating spinal axons whose cell bodies are located rostral or caudal to the TX and confirmed the regeneration of many small RS axons as early as 2 weeks post-TX. Compared with the behavior of axotomized giant axons, the early regenerating axons were of small caliber and showed little retraction, probably because they resealed rapidly after injury.
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Affiliation(s)
- Guixin Zhang
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Philadelphia, PA 19140, USA; (G.Z.); (W.R.); (J.H.)
| | - William Rodemer
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Philadelphia, PA 19140, USA; (G.Z.); (W.R.); (J.H.)
| | - Isabelle Sinitsa
- College of Science and Technology, Temple University, Philadelphia, PA 19122, USA;
| | - Jianli Hu
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Philadelphia, PA 19140, USA; (G.Z.); (W.R.); (J.H.)
| | - Michael E. Selzer
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Philadelphia, PA 19140, USA; (G.Z.); (W.R.); (J.H.)
- Department of Neurology, the Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA 19140, USA
- Correspondence:
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Rodemer W, Zhang G, Sinitsa I, Hu J, Jin LQ, Li S, Selzer ME. PTPσ Knockdown in Lampreys Impairs Reticulospinal Axon Regeneration and Neuronal Survival After Spinal Cord Injury. Front Cell Neurosci 2020; 14:61. [PMID: 32265663 PMCID: PMC7096546 DOI: 10.3389/fncel.2020.00061] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 03/02/2020] [Indexed: 01/10/2023] Open
Abstract
Traumatic spinal cord injury (SCI) results in persistent functional deficits due to the lack of axon regeneration within the mammalian CNS. After SCI, chondroitin sulfate proteoglycans (CSPGs) inhibit axon regrowth via putative interactions with the LAR-family protein tyrosine phosphatases, PTPσ and LAR, localized on the injured axon tips. Unlike mammals, the sea lamprey, Petromyzon marinus, robustly recovers locomotion after complete spinal cord transection (TX). Behavioral recovery is accompanied by heterogeneous yet predictable anatomical regeneration of the lamprey's reticulospinal (RS) system. The identified RS neurons can be categorized as "good" or "bad" regenerators based on the likelihood that their axons will regenerate. Those neurons that fail to regenerate their axons undergo a delayed form of caspase-mediated cell death. Previously, this lab reported that lamprey PTPσ mRNA is selectively expressed in "bad regenerator" RS neurons, preceding SCI-induced caspase activation. Consequently, we hypothesized that PTPσ deletion would reduce retrograde cell death and promote axon regeneration. Using antisense morpholino oligomers (MOs), we knocked down PTPσ expression after TX and assessed the effects on axon regeneration, caspase activation, intracellular signaling, and behavioral recovery. Unexpectedly, PTPσ knockdown significantly impaired RS axon regeneration at 10 weeks post-TX, primarily due to reduced long-term neuron survival. Interestingly, cell loss was not preceded by an increase in caspase or p53 activation. Behavioral recovery was largely unaffected, although PTPσ knockdowns showed mild deficits in the recovery of swimming distance and latency to immobility during open field swim assays. Although the mechanism underlying the cell death following TX and PTPσ knockdown remains unknown, this study suggests that PTPσ is not a net negative regulator of long tract axon regeneration in lampreys.
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Affiliation(s)
- William Rodemer
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Guixin Zhang
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Isabelle Sinitsa
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
- College of Science and Technology, Temple University, Philadelphia, PA, United States
| | - Jianli Hu
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Li-qing Jin
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Shuxin Li
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
- Department of Anatomy and Cell Biology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Michael E. Selzer
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
- Department of Neurology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
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Sobrido-Cameán D, Fernández-López B, Pereiro N, Lafuente A, Rodicio MC, Barreiro-Iglesias A. Taurine Promotes Axonal Regeneration after a Complete Spinal Cord Injury in Lampreys. J Neurotrauma 2020; 37:899-903. [DOI: 10.1089/neu.2019.6604] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Daniel Sobrido-Cameán
- Department of Functional Biology, Universidade de Santiago de Compostela, Compostela, Spain
| | - Blanca Fernández-López
- Department of Functional Biology, Universidade de Santiago de Compostela, Compostela, Spain
- Department of Anatomy, University of Helsinki, Helsinki, Finland
| | - Natividad Pereiro
- Laboratory of Toxicology, University of Vigo, Ourense, Spain
- Tragsatec, Madrid, Spain
| | | | - María Celina Rodicio
- Department of Functional Biology, Universidade de Santiago de Compostela, Compostela, Spain
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Rodemer W, Hu J, Selzer ME, Shifman MI. Heterogeneity in the regenerative abilities of central nervous system axons within species: why do some neurons regenerate better than others? Neural Regen Res 2020; 15:996-1005. [PMID: 31823869 PMCID: PMC7034288 DOI: 10.4103/1673-5374.270298] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Some neurons, especially in mammalian peripheral nervous system or in lower vertebrate or in vertebrate central nervous system (CNS) regenerate after axotomy, while most mammalian CNS neurons fail to regenerate. There is an emerging consensus that neurons have different intrinsic regenerative capabilities, which theoretically could be manipulated therapeutically to improve regeneration. Population-based comparisons between “good regenerating” and “bad regenerating” neurons in the CNS and peripheral nervous system of most vertebrates yield results that are inconclusive or difficult to interpret. At least in part, this reflects the great diversity of cells in the mammalian CNS. Using mammalian nervous system imposes several methodical limitations. First, the small sizes and large numbers of neurons in the CNS make it very difficult to distinguish regenerating neurons from non-regenerating ones. Second, the lack of identifiable neurons makes it impossible to correlate biochemical changes in a neuron with axonal damage of the same neuron, and therefore, to dissect the molecular mechanisms of regeneration on the level of single neurons. This review will survey the reported responses to axon injury and the determinants of axon regeneration, emphasizing non-mammalian model organisms, which are often under-utilized, but in which the data are especially easy to interpret.
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Affiliation(s)
- William Rodemer
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), the Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Jianli Hu
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), the Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Michael E Selzer
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation); Department of Neurology, the Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Michael I Shifman
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), the Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
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Yamashita T. Neogenin is a Determining Factor for Regenerating Neurons Following Spinal Cord Injury. Neuroscience 2019; 408:448-449. [DOI: 10.1016/j.neuroscience.2018.12.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 12/13/2018] [Accepted: 12/14/2018] [Indexed: 01/13/2023]
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Chen J, Shifman MI. Inhibition of neogenin promotes neuronal survival and improved behavior recovery after spinal cord injury. Neuroscience 2019; 408:430-447. [PMID: 30943435 DOI: 10.1016/j.neuroscience.2019.03.055] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 03/22/2019] [Accepted: 03/26/2019] [Indexed: 01/09/2023]
Abstract
Following spinal cord trauma, axonal regeneration in the mammalian spinal cord does not occur and functional recovery may be further impeded by retrograde neuronal death. By contrast, lampreys recover after spinal cord injury (SCI) and axons re-connected to their targets in spinal cord. However, the identified reticulospinal (RS) neurons located in the lamprey brain differ in their regenerative capacities - some are good regenerators, and others are bad regenerators - despite the fact that they have analogous projection pathways. Previously, we reported that axonal guidance receptor Neogenin involved in regulation of axonal regeneration after SCI and downregulation of Neogenin synthesis by morpholino oligonucleotides (MO) enhanced the regeneration of RS neurons. Incidentally, the bad regenerating RS neurons often undergo a late retrograde apoptosis after SCI. Here we report that, after SCI, expression of RGMa mRNA was upregulated around the transection site, while its receptor Neogenin continued to be synthesized almost inclusively in the "bad-regenerating" RS neurons. Inhibition of Neogenin by MO prohibited activation of caspases and improved the survival of RS neurons at 10 weeks after SCI. These data provide new evidence in vivo that Neogenin is involved in retrograde neuronal death and failure of axonal regeneration after SCI.
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Affiliation(s)
- Jie Chen
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Philadelphia, PA 19140, USA
| | - Michael I Shifman
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Philadelphia, PA 19140, USA; Department of Neuroscience, Temple University School of Medicine, 3500 North Broad Street, Philadelphia, PA 19140, USA.
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Rodemer W, Selzer ME. Role of axon resealing in retrograde neuronal death and regeneration after spinal cord injury. Neural Regen Res 2019; 14:399-404. [PMID: 30539805 PMCID: PMC6334596 DOI: 10.4103/1673-5374.245330] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Spinal cord injury leads to persistent behavioral deficits because mammalian central nervous system axons fail to regenerate. A neuron's response to axon injury results from a complex interplay of neuron-intrinsic and environmental factors. The contribution of axotomy to the death of neurons in spinal cord injury is controversial because very remote axotomy is unlikely to result in neuronal death, whereas death of neurons near an injury may reflect environmental factors such as ischemia and inflammation. In lampreys, axotomy due to spinal cord injury results in delayed apoptosis of spinal-projecting neurons in the brain, beyond the extent of these environmental factors. This retrograde apoptosis correlates with delayed resealing of the axon, and can be reversed by inducing rapid membrane resealing with polyethylene glycol. Studies in mammals also suggest that polyethylene glycol may be neuroprotective, although the mechanism(s) remain unclear. This review examines the early, mechanical, responses to axon injury in both mammals and lampreys, and the potential of polyethylene glycol to reduce injury-induced pathology. Identifying the mechanisms underlying a neuron's response to axotomy will potentially reveal new therapeutic targets to enhance regeneration and functional recovery in humans with spinal cord injury.
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Affiliation(s)
- William Rodemer
- Shriners Hospital Pediatric Research Center (Center for Neural Repair and Rehabilitation), Philadelphia, PA, USA
| | - Michael E Selzer
- Shriners Hospital Pediatric Research Center (Center for Neural Repair and Rehabilitation); Department of Neurology, the Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
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12
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GABA promotes survival and axonal regeneration in identifiable descending neurons after spinal cord injury in larval lampreys. Cell Death Dis 2018; 9:663. [PMID: 29950557 PMCID: PMC6021415 DOI: 10.1038/s41419-018-0704-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 04/24/2018] [Accepted: 05/14/2018] [Indexed: 12/25/2022]
Abstract
The poor regenerative capacity of descending neurons is one of the main causes of the lack of recovery after spinal cord injury (SCI). Thus, it is of crucial importance to find ways to promote axonal regeneration. In addition, the prevention of retrograde degeneration leading to the atrophy/death of descending neurons is an obvious prerequisite to activate axonal regeneration. Lampreys show an amazing regenerative capacity after SCI. Recent histological work in lampreys suggested that GABA, which is massively released after a SCI, could promote the survival of descending neurons. Here, we aimed to study if GABA, acting through GABAB receptors, promotes the survival and axonal regeneration of descending neurons of larval sea lampreys after a complete SCI. First, we used in situ hybridization to confirm that identifiable descending neurons of late-stage larvae express the gabab1 subunit of the GABAB receptor. We also observed an acute increase in the expression of this subunit in descending neurons after SCI, which further supported the possible role of GABA and GABAB receptors in promoting the survival and regeneration of these neurons. So, we performed gain and loss of function experiments to confirm this hypothesis. Treatments with GABA and baclofen (GABAB agonist) significantly reduced caspase activation in descending neurons 2 weeks after a complete SCI. Long-term treatments with GABOB (a GABA analogue) and baclofen significantly promoted axonal regeneration of descending neurons after SCI. These data indicate that GABAergic signalling through GABAB receptors promotes the survival and regeneration of descending neurons after SCI. Finally, we used morpholinos against the gabab1 subunit to knockdown the expression of the GABAB receptor in descending neurons. Long-term morpholino treatments caused a significant inhibition of axonal regeneration. This shows that endogenous GABA promotes axonal regeneration after a complete SCI in lampreys by activating GABAB receptors.
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13
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Zhang G, Hu J, Rodemer W, Li S, Selzer ME. RhoA activation in axotomy-induced neuronal death. Exp Neurol 2018; 306:76-91. [PMID: 29715475 DOI: 10.1016/j.expneurol.2018.04.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 04/18/2018] [Accepted: 04/27/2018] [Indexed: 01/11/2023]
Abstract
After spinal cord injury (SCI) in mammals, severed axons fail to regenerate, due to both extrinsic inhibitory factors, e.g., the chondroitin sulfate proteoglycans (CSPGs) and myelin-associated growth inhibitors (MAIs), and a developmental loss of intrinsic growth capacity. The latter is suggested by findings in lamprey that the 18 pairs of individually identified reticulospinal neurons vary greatly in their ability to regenerate their axons through the same spinal cord environment. Moreover, those neurons that are poor regenerators undergo very delayed apoptosis, and express common molecular markers after SCI. Thus the signaling pathways for retrograde cell death might converge with those inhibiting axon regeneration. Many extrinsic growth-inhibitory molecules activate RhoA, whereas inhibiting RhoA enhances axon growth. Whether RhoA also is involved in retrograde neuronal death after axotomy is less clear. Therefore, we cloned lamprey RhoA and correlated its mRNA expression and activation state with apoptosis signaling in identified reticulospinal neurons. RhoA mRNA was expressed widely in normal lamprey brain, and only slightly more in poorly-regenerating neurons than in good regenerators. However, within a day after spinal cord transection, RhoA mRNA was found in severed axon tips. Beginning at 5 days post-SCI RhoA mRNA was upregulated selectively in pre-apoptotic neuronal perikarya, as indicated by labelling with fluorescently labeled inhibitors of caspase activation (FLICA). After 2 weeks post-transection, RhoA expression decreased in the perikarya, and was translocated anterogradely into the axons. More striking than changes in RhoA mRNA levels, RhoA was continuously active selectively in FLICA-positive neurons through 9 weeks post-SCI. At that time, almost no neurons whose axons had regenerated were FLICA-positive. These findings are consistent with a role for RhoA activation in triggering retrograde neuronal death after SCI, and suggest that RhoA may be a point of convergence for inhibition of both axon regeneration and neuronal survival after axotomy.
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Affiliation(s)
- Guixin Zhang
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), USA
| | - Jianli Hu
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), USA
| | - William Rodemer
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), USA
| | - Shuxin Li
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), USA; Dept. Anatomy and Cell Biology, The Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA 19140, USA
| | - Michael E Selzer
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), USA; Dept. of Neurology, USA.
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Sobrido-Cameán D, Barreiro-Iglesias A. Role of Caspase-8 and Fas in Cell Death After Spinal Cord Injury. Front Mol Neurosci 2018; 11:101. [PMID: 29666570 PMCID: PMC5891576 DOI: 10.3389/fnmol.2018.00101] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 03/15/2018] [Indexed: 01/10/2023] Open
Abstract
Spinal cord injury (SCI) causes the death of neurons and glial cells due to the initial mechanical forces (i.e., primary injury) and through a cascade of secondary molecular events (e.g., inflammation or excitotoxicity) that exacerbate cell death. The loss of neurons and glial cells that are not replaced after the injury is one of the main causes of disability after SCI. Evidence accumulated in last decades has shown that the activation of apoptotic mechanisms is one of the factors causing the death of intrinsic spinal cord (SC) cells following SCI. Although this is not as clear for brain descending neurons, some studies have also shown that apoptosis can be activated in the brain following SCI. There are two main apoptotic pathways, the extrinsic and the intrinsic pathways. Activation of caspase-8 is an important step in the initiation of the extrinsic pathway. Studies in rodents have shown that caspase-8 is activated in SC glial cells and neurons and that the Fas receptor plays a key role in its activation following a traumatic SCI. Recent work in the lamprey model of SCI has also shown the retrograde activation of caspase-8 in brain descending neurons following SCI. Here, we review our current knowledge on the role of caspase-8 and the Fas pathway in cell death following SCI. We also provide a perspective for future work on this process, like the importance of studying the possible contribution of Fas/caspase-8 signaling in the degeneration of brain neurons after SCI in mammals.
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Affiliation(s)
- Daniel Sobrido-Cameán
- Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Antón Barreiro-Iglesias
- Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
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15
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Retrograde Activation of the Extrinsic Apoptotic Pathway in Spinal-Projecting Neurons after a Complete Spinal Cord Injury in Lampreys. BIOMED RESEARCH INTERNATIONAL 2017; 2017:5953674. [PMID: 29333445 PMCID: PMC5733621 DOI: 10.1155/2017/5953674] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 10/25/2017] [Indexed: 12/15/2022]
Abstract
Spinal cord injury (SCI) is a devastating condition that leads to permanent disability because injured axons do not regenerate across the trauma zone to reconnect to their targets. A prerequisite for axonal regeneration will be the prevention of retrograde degeneration that could lead to neuronal death. However, the specific molecular mechanisms of axotomy-induced degeneration of spinal-projecting neurons have not been elucidated yet. In lampreys, SCI induces the apoptotic death of identifiable descending neurons that are “bad regenerators/poor survivors” after SCI. Here, we investigated the apoptotic process activated in identifiable descending neurons of lampreys after SCI. For this, we studied caspase activation by using fluorochrome-labeled inhibitors of caspases, the degeneration of spinal-projecting neurons using Fluro-Jade C staining, and the involvement of the intrinsic apoptotic pathway by means of cytochrome c and Vα double immunofluorescence. Our results provide evidence that, after SCI, bad-regenerating spinal cord-projecting neurons slowly degenerate and that the extrinsic pathway of apoptosis is involved in this process. Experiments using the microtubule stabilizer Taxol showed that caspase-8 signaling is retrogradely transported by microtubules from the site of axotomy to the neuronal soma. Preventing the activation of this process could be an important therapeutic approach after SCI in mammals.
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16
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Hu J, Zhang G, Rodemer W, Jin LQ, Shifman M, Selzer ME. The role of RhoA in retrograde neuronal death and axon regeneration after spinal cord injury. Neurobiol Dis 2016; 98:25-35. [PMID: 27888137 DOI: 10.1016/j.nbd.2016.11.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 10/24/2016] [Accepted: 11/20/2016] [Indexed: 01/13/2023] Open
Abstract
Paralysis following spinal cord injury (SCI) is due to interruption of axons and their failure to regenerate. It has been suggested that the small GTPase RhoA may be an intracellular signaling convergence point for several types of growth-inhibiting extracellular molecules. Even if this is true in vitro, it is not clear from studies in mammalian SCI, whether the effects of RhoA manipulations on axon growth in vivo are due to a RhoA-mediated inhibition of true regeneration or only of collateral sprouting from spared axons, since work on SCI generally is performed with partial injury models. RhoA also has been implicated in local neuronal apoptosis after SCI, but whether this reflects an effect on axotomy-induced cell death or an effect on other pathological mechanisms is not known. In order to resolve these ambiguities, we studied the effects of RhoA knockdown in the sea lamprey central nervous system (CNS), where after complete spinal cord transection (TX), robust but incomplete regeneration of large axons belonging to individually identified reticulospinal (RS) neurons occurs, and where some RS neurons show unambiguous delayed retrograde apoptosis after axotomy. RhoA protein was detected in neurons and axons of the lamprey brain and spinal cord, and its expression was increased post-TX. Knockdown of RhoA in vivo by retrogradely-delivered morpholino antisense oligonucleotides (MOs) to the RS neurons significantly reduced retrograde apoptosis signaling in identified RS neurons post-SCI, as indicated by Fluorochrome Labeled Inhibitor of Caspases (FLICA) in brain wholemounts. In individual RS neurons, the reduction of caspase activation by RhoA knockdown began at 2weeks post-TX and was still seen at 8weeks. RhoA knockdown slowed axon retraction and possibly increased early axon regeneration in the proximal stump. The number of axons regenerating beyond the lesion more than 5mm at 10weeks post-TX also was increased. Thus RhoA knockdown both enhanced true axon regeneration and inhibited retrograde apoptosis signaling after SCI.
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Affiliation(s)
- Jianli Hu
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA 19140, USA
| | - Guixin Zhang
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA 19140, USA
| | - William Rodemer
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA 19140, USA
| | - Li-Qing Jin
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA 19140, USA
| | - Michael Shifman
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA 19140, USA
| | - Michael E Selzer
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA 19140, USA; Dept. of Neurology, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA 19140, USA.
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17
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Jin LQ, Pennise CR, Rodemer W, Jahn KS, Selzer ME. Protein synthetic machinery and mRNA in regenerating tips of spinal cord axons in lamprey. J Comp Neurol 2016; 524:3614-3640. [PMID: 27120118 DOI: 10.1002/cne.24020] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 04/11/2016] [Accepted: 04/12/2016] [Indexed: 02/03/2023]
Abstract
Polyribosomes, mRNA, and other elements of translational machinery have been reported in peripheral nerves and in elongating injured axons of sensory neurons in vitro, primarily in growth cones. Evidence for involvement of local protein synthesis in regenerating central nervous system (CNS) axons is less extensive. We monitored regeneration of back-labeled lamprey spinal axons after spinal cord transection and detected mRNA in axon tips by in situ hybridization and microaspiration of their axoplasm. Poly(A)+mRNA was present in the axon tips, and was more abundant in actively regenerating tips than in static or retracting ones. Target-specific polymerase chain reaction (PCR) and in situ hybridization revealed plentiful mRNA for the low molecular neurofilament subunit and β-tubulin, but very little for β-actin, consistent with the morphology of their tips, which lack filopodia and lamellipodia. Electron microscopy showed ribosomes/polyribosomes in the distal parts of axon tips and in association with vesicle-like membranes, primarily in the tip. In one instance, there were structures with the appearance of rough endoplasmic reticulum. Immunohistochemistry showed patches of ribosomal protein S6 positivity in a similar distribution. The results suggest that local protein synthesis might be involved in the mechanism of axon regeneration in the lamprey spinal cord. J. Comp. Neurol. 524:3614-3640, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Li-Qing Jin
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140.
| | - Cynthia R Pennise
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140
| | - William Rodemer
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140
| | - Kristen S Jahn
- The Children's Hospital of Philadelphia, 1108 Pine Street, Philadelphia, PA, 19107
| | - Michael E Selzer
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140. .,Department of Neurology, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140.
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18
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Fogerson SM, van Brummen AJ, Busch DJ, Allen SR, Roychaudhuri R, Banks SML, Klärner FG, Schrader T, Bitan G, Morgan JR. Reducing synuclein accumulation improves neuronal survival after spinal cord injury. Exp Neurol 2016; 278:105-15. [PMID: 26854933 DOI: 10.1016/j.expneurol.2016.02.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 01/29/2016] [Accepted: 02/04/2016] [Indexed: 11/25/2022]
Abstract
Spinal cord injury causes neuronal death, limiting subsequent regeneration and recovery. Thus, there is a need to develop strategies for improving neuronal survival after injury. Relative to our understanding of axon regeneration, comparatively little is known about the mechanisms that promote the survival of damaged neurons. To address this, we took advantage of lamprey giant reticulospinal neurons whose large size permits detailed examination of post-injury molecular responses at the level of individual, identified cells. We report here that spinal cord injury caused a select subset of giant reticulospinal neurons to accumulate synuclein, a synaptic vesicle-associated protein best known for its atypical aggregation and causal role in neurodegeneration in Parkinson's and other diseases. Post-injury synuclein accumulation took the form of punctate aggregates throughout the somata and occurred selectively in dying neurons, but not in those that survived. In contrast, another synaptic vesicle protein, synaptotagmin, did not accumulate in response to injury. We further show that the post-injury synuclein accumulation was greatly attenuated after single dose application of either the "molecular tweezer" inhibitor, CLR01, or a translation-blocking synuclein morpholino. Consequently, reduction of synuclein accumulation not only improved neuronal survival, but also increased the number of axons in the spinal cord proximal and distal to the lesion. This study is the first to reveal that reducing synuclein accumulation is a novel strategy for improving neuronal survival after spinal cord injury.
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Affiliation(s)
- Stephanie M Fogerson
- Marine Biological Laboratory, The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Woods Hole, MA 02543, United States
| | - Alexandra J van Brummen
- Marine Biological Laboratory, The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Woods Hole, MA 02543, United States; Section of Molecular Cell and Developmental Biology, The University of Texas at Austin, Austin, TX 78712, United States
| | - David J Busch
- Section of Molecular Cell and Developmental Biology, The University of Texas at Austin, Austin, TX 78712, United States
| | - Scott R Allen
- Marine Biological Laboratory, The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Woods Hole, MA 02543, United States
| | - Robin Roychaudhuri
- Department of Neurology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095, United States
| | - Susan M L Banks
- Marine Biological Laboratory, The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Woods Hole, MA 02543, United States
| | - Frank-Gerrit Klärner
- Institute of Organic Chemistry, University of Duisburg-Essen, Essen 45117, Germany
| | - Thomas Schrader
- Institute of Organic Chemistry, University of Duisburg-Essen, Essen 45117, Germany
| | - Gal Bitan
- Department of Neurology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095, United States; Brain Research Institute and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, CA 90095, United States
| | - Jennifer R Morgan
- Marine Biological Laboratory, The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Woods Hole, MA 02543, United States.
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19
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Barreiro-Iglesias A, Shifman MI. Detection of activated caspase-8 in injured spinal axons by using fluorochrome-labeled inhibitors of caspases (FLICA). Methods Mol Biol 2015; 1254:329-39. [PMID: 25431075 DOI: 10.1007/978-1-4939-2152-2_23] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Here, we present a detailed protocol for the detection of activated caspase-8 in axotomized axons of the whole-mounted lamprey spinal cord. This method is based on the use of fluorochrome -labeled inhibitors of caspases (FLICA) in ex vivo tissue. We offer a very convenient vertebrate model to study the retrograde degeneration of descending pathways after spinal cord injury.
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Affiliation(s)
- Antón Barreiro-Iglesias
- Centre for Neuroregeneration, School of Biomedical Sciences, University of Edinburgh, 49 Little France Crescent, Edinburgh, EH16 4SB, UK,
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20
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Zhang G, Hu J, Li S, Huang L, Selzer ME. Selective expression of CSPG receptors PTPσ and LAR in poorly regenerating reticulospinal neurons of lamprey. J Comp Neurol 2014; 522:2209-29. [DOI: 10.1002/cne.23529] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Revised: 12/16/2013] [Accepted: 12/17/2013] [Indexed: 12/26/2022]
Affiliation(s)
- Guixin Zhang
- Center for Neural Repair and Rehabilitation; Shriners Hospitals Pediatric Research Center; Philadelphia Pennsylvania 19140
| | - Jianli Hu
- Center for Neural Repair and Rehabilitation; Shriners Hospitals Pediatric Research Center; Philadelphia Pennsylvania 19140
| | - Shuxin Li
- Center for Neural Repair and Rehabilitation; Shriners Hospitals Pediatric Research Center; Philadelphia Pennsylvania 19140
| | - Lisa Huang
- Center for Neural Repair and Rehabilitation; Shriners Hospitals Pediatric Research Center; Philadelphia Pennsylvania 19140
| | - Michael E. Selzer
- Center for Neural Repair and Rehabilitation; Shriners Hospitals Pediatric Research Center; Philadelphia Pennsylvania 19140
- Department of Neurology; Temple University School of Medicine; 3500 North Broad Street Philadelphia Pennsylvania 19140
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