Axonal degeneration is a key pathological feature in many neurological diseases. It often leads to persistent deficits due to the inability of axons to regenerate in the central nervous system. Therefore therapeutic a...Axonal degeneration is a key pathological feature in many neurological diseases. It often leads to persistent deficits due to the inability of axons to regenerate in the central nervous system. Therefore therapeutic approaches should optimally both attenuate axonal degeneration and foster axonal regeneration. Compelling evidence suggests that collapsin response mediator protein-2（CRMP2） might be a molecular target fulfilling these requirements. In this mini-review, we give a compact overview of the known functions of CRMP2 and its molecular interactors in neurite outgrowth and in neurodegenerative conditions. Moreover, we discuss in detail our recent findings on the role of CRMP2 in acute axonal degeneration in the optic nerve. We found that the calcium influx induced by the lesion activates the protease calpain which cleaves CRMP2, leading to impairment of axonal transport. Both calpain inhibition and CRMP2 overexpression effectively protected the proximal axons against acute axonal degeneration. Taken together, CRMP2 is further characterized as a central molecular player in acute axonal degeneration and thus evolves as a promising therapeutic target to both counteract axonal degeneration and foster axonal regeneration in neurodegenerative and neurotraumatic diseases.展开更多
Alzheimer’s disease（AD）is a neurodegenerative disorder characterized by accumulation of amyloid plaques and neurofibrillary tangles.Prior to the development of these characteristic pathological hallmarks of AD,ante...Alzheimer’s disease（AD）is a neurodegenerative disorder characterized by accumulation of amyloid plaques and neurofibrillary tangles.Prior to the development of these characteristic pathological hallmarks of AD,anterograde axonal transport is impaired.However,the key proteins that initiate these intracellular impairments remain elusive.The collapsin response mediator protein-2（CRMP-2）plays an integral role in kinesin-1-dependent axonal transport and there is evidence that phosphorylation of CRMP-2releases kinesin-1.Here,we tested the hypothesis that amyloid-beta（Aβ）-dependent phosphorylation of CRMP-2 disrupts its association with the kinesin-1（an anterograde axonal motor transport protein）in AD.We found that brain sections and lysates from AD patients demonstrated elevated phosphorylation of CRMP-2 at the T555 site.Additionally,in the transgenic Tg2576 mouse model of familial AD（FAD）that exhibits Aβaccumulation in the brain with age,we found substantial co-localization of p T555CRMP-2and dystrophic neurites.In SH-SY5Y differentiated neuronal cultures,Aβ-dependent phosphorylation of CRMP-2 at the T555 site was also elevated and this reduced the CRMP-2 association with kinesin-1.The overexpression of an unphosphorylatable form of CRMP-2 in neurons promoted the re-establishment of CRMP-2-kinesin association and axon elongation.These data suggest that Aβ-dependent phosphorylation of CRMP-2 at the T555 site may directly impair anterograde axonal transport protein function,leading to neuronal defects.展开更多
The brain is a complex network system that has the capacity to support emotion, thought, action, learning and memory, and is characterized by constant activity, constant structural remodeling, and constant attempt to ...The brain is a complex network system that has the capacity to support emotion, thought, action, learning and memory, and is characterized by constant activity, constant structural remodeling, and constant attempt to compensate for this remodeling. The basic insight that emerges from complex network organization is that substantively different networks can share common key organizational principles. Moreover, the interdependence of network organization and behavior has been successfully demonstrated for several specific tasks. From this viewpoint, increasing experimental/clinical observations suggest that mental disorders are neural network disorders. On one hand, single psychiatric disorders arise from multiple, multifactorial molecular and cellular structural/functional alterations spreading throughout local/global circuits leading to multifaceted and heterogeneous clinical symptoms. On the other hand, various mental diseases may share functional deficits across the same neural circuit as reflected in the overlap of symptoms throughout clinical diagnoses. An integrated framework including experimental measures and clinical observations will be necessary to formulate a coherent and comprehensive understanding of how neural connectivity mediates and constraints the phenotypic expression of psychiatric disorders.展开更多
This study examined the role of collapsin response mediator protein 1 （CRMP-1） on neurite outgrowth from rat hippocampal neurons by blocking its function using an antibody. Hippocampal neurons, cultured in vitro, we...This study examined the role of collapsin response mediator protein 1 （CRMP-1） on neurite outgrowth from rat hippocampal neurons by blocking its function using an antibody. Hippocampal neurons, cultured in vitro, were treated （blocked） using a polyclonal antibody to CRMP-1, and neurite outgrowth and cytoskeletal changes were captured using atomic force microscopy and laser confocal microscopy. Control cells, treated with normal rabbit IgG, established their characteristic morphology and had a large number of processes emerging from the soma, including numerous branches. Microtubules were clearly visible in the soma, formed an elaborate network, and were aligned in parallel arrays to form bundles which projected into neurites. After blocking with CRMP-1 antibody, the number of branches emerging from axons and dendrites significantly increased and were substantially longer, compared with control cells. However, the microtubule network nearly disappeared and only a few remnants were visible. When CRMP-1 antibody-blocked neurons were treated with the Rho inhibitor, Y27632, numerous neurites emerged from the soma, and branches were more abundant than in control neurons. Although the microtubules were not as clearly visible compared with neurons cultured in control medium, the microtubule network recovered in cells treated with Y27632, when compared with cells that were blocked by CRMP-1 antibody （but not treated with Y27632）. These results demonstrate that neurite outgrowth from hippocampal neurons can be promoted by blocking CRMP-1 with a polyclonal antibody.展开更多
Cytoskeletal microtubule rearrangement and movement are crucial in the repair of spinal cord injury.Spastin plays an important role in the regulation of microtubule severing.Both spastin and collapsin response mediato...Cytoskeletal microtubule rearrangement and movement are crucial in the repair of spinal cord injury.Spastin plays an important role in the regulation of microtubule severing.Both spastin and collapsin response mediator proteins can regulate neurite growth and branching;however,whether spastin interacts with collapsin response mediator protein 3(CRMP3)during this process remains unclear,as is the mechanism by which CRMP3 participates in the repair of spinal cord injury.In this study,we used a proteomics approach to identify key proteins associated with spinal cord injury repair.We then employed liquid chromatography-mass spectrometry to identify proteins that were able to interact with glutathione S-transferase-spastin.Then,co-immunoprecipitation and staining approaches were used to evaluate potential interactions between spastin and CRMP3.Finally,we co-transfected primary hippocampal neurons with CRMP3 and spastin to evaluate their role in neurite outgrowth.Mass spectrometry identified the role of CRMP3 in the spinal cord injury repair process.Liquid chromatography-mass spectrometry pulldown assays identified three CRMP3 peptides that were able to interact with spastin.CRMP3 and spastin were co-expressed in the spinal cord and were able to interact with one another in vitro and in vivo.Lastly,CRMP3 overexpression was able to enhance the ability of spastin to promote neurite growth and branching.Therefore,our results confirm that spastin and CRMP3 play roles in spinal cord injury repair by regulating neurite growth and branching.These proteins may therefore be novel targets for spinal cord injury repair.The Institutional Animal Care and Use Committee of Jinan University,China approved this study(approval No.IACUS-20181008-03)on October 8,2018.展开更多
Background： Collapsin response mediator protein-2 （CRMP2）, a multifunctional cytosolic protein highly expressed in the brain, is degraded by calpain following traumatic brain injury （TBI）, possibly inhibiting pos...Background： Collapsin response mediator protein-2 （CRMP2）, a multifunctional cytosolic protein highly expressed in the brain, is degraded by calpain following traumatic brain injury （TBI）, possibly inhibiting posttraumatic neurite regeneration. Lipid peroxidation （LP） is involved in triggering postinjury CRMP2 proteolysis. We examined the hypothesis that propo（bl could attenuate LP, calpain-induced CRMP2 degradation, and brain injury after TBI. Methods： A unilateral moderate controlled cortical impact injury was induced in adult male Sprague-Dawley rats. The animals were randomly divided into seven groups： Sham control group, TBI group, TB1 ＋ propofol groups （including propofol I h, 2 h, and 4 h groups）, TBI ＋ U83836E group and TBI ＋ fat emulsion group. The LP inhibitor U83836E was used as a control to identify that antioxidation partially accounts for the potential neuroprotective effects of propofol. The solvent of propofol, （＇at emulsion, was used as the vehicle control, lpsilateral cortex tissues were harvested at 24 h post-TBI. Immunofluorescent staining, Western blot analysis, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling were used to evaluate LP, calpain activity, CRMP2 proteolysis and programmed cell death. The data were statistically analyzed using one-way analysis of variance and a paired t-test. Results： Propofol and U83836E significantly ameliorated the CRMP2 proteolysis, In addition, both propofol and U83836E significantly decreased the ratio of 145-kDa cdl-spectrin breakdown products to intact 270-kDa spectrin, the 4-hydroxynonenal expression and programmed cell death in the pericontusional cortex at 24 h after TBI. There was no difference between the TB1 group and the （＇at emulsion group. Conclusions： These results demonstrate that propofol postconditioning alleviates calpain-mediated CRMP2 proteolysis and provides neuroprotective effects following moderate TBI potentially by counteracting LP and reducing calpain activation.展开更多
Background： Collapsin response mediator protein-2 （CRMP2） has been shown to be involved in ischemia/hypoxia （IH） injury. We determined whether CRMP2 modulates ischemic injury in the retinal of Ocular ischemic syn...Background： Collapsin response mediator protein-2 （CRMP2） has been shown to be involved in ischemia/hypoxia （IH） injury. We determined whether CRMP2 modulates ischemic injury in the retinal of Ocular ischemic syndrome （OIS）. This study was to explore the molecular mechanisms underlying O1S in a novel mice model. Methods： Experiments were performed oil adult male C57/BL6 mice that received bilateral internal carotid arteries ligation for 1,2, or 4 weeks. The mice received injection of calpeptin group before occlusion for 4 weeks or not. The expression of CRMP2 in the retinal was exalnined by western blotting （WB） analysis and immunohistochemical analysis （IHC）. The effects of ischemic injury on retinal were evaluated by fundus examination, fundus fluorescein angiography, electroretinogram, cell cotinting of retinal ganglion cell （RGC）, and measurement of the thickness of the retina. Results： The veins dilated after chronic ischemia. In the electroretinography, the amplitudes of a- and b-waves kept diminishing in an ischemia time-dependent manner. Moreover, the tail vein-retinal circulation time prolonged in the l- and 2-week group. In comparison, thickness of the retina decreased gradually with the ischemia time elapsed. WB analysis showed the CRMP2 and p-CRMP2 levels decreased in the 2- and 4-week groups. The results of IHC analysis were compatible with our results of WB. The loss of RGCs, decrease of the total reaction time and reduction of CRMP2 was alleviated by intravitreal injection of calpeptin. Conclusions： These results revealed that bilateral ligation of the internal carotid artery causes retinal ischemia in mice. Moreover, CRMP2 might play a pivotal role during the ischemic injury in the retina and inhibit the cleavage of CRM P2 can ameliorate the IH injury.展开更多
文摘Axonal degeneration is a key pathological feature in many neurological diseases. It often leads to persistent deficits due to the inability of axons to regenerate in the central nervous system. Therefore therapeutic approaches should optimally both attenuate axonal degeneration and foster axonal regeneration. Compelling evidence suggests that collapsin response mediator protein-2（CRMP2） might be a molecular target fulfilling these requirements. In this mini-review, we give a compact overview of the known functions of CRMP2 and its molecular interactors in neurite outgrowth and in neurodegenerative conditions. Moreover, we discuss in detail our recent findings on the role of CRMP2 in acute axonal degeneration in the optic nerve. We found that the calcium influx induced by the lesion activates the protease calpain which cleaves CRMP2, leading to impairment of axonal transport. Both calpain inhibition and CRMP2 overexpression effectively protected the proximal axons against acute axonal degeneration. Taken together, CRMP2 is further characterized as a central molecular player in acute axonal degeneration and thus evolves as a promising therapeutic target to both counteract axonal degeneration and foster axonal regeneration in neurodegenerative and neurotraumatic diseases.
基金supported by King Abdul-Aziz University postgraduate scholarship(to SHM)the National Multiple Sclerosis Society(USA)Project Grant ID#RG43981/1(to SP)
文摘Alzheimer’s disease（AD）is a neurodegenerative disorder characterized by accumulation of amyloid plaques and neurofibrillary tangles.Prior to the development of these characteristic pathological hallmarks of AD,anterograde axonal transport is impaired.However,the key proteins that initiate these intracellular impairments remain elusive.The collapsin response mediator protein-2（CRMP-2）plays an integral role in kinesin-1-dependent axonal transport and there is evidence that phosphorylation of CRMP-2releases kinesin-1.Here,we tested the hypothesis that amyloid-beta（Aβ）-dependent phosphorylation of CRMP-2 disrupts its association with the kinesin-1（an anterograde axonal motor transport protein）in AD.We found that brain sections and lysates from AD patients demonstrated elevated phosphorylation of CRMP-2 at the T555 site.Additionally,in the transgenic Tg2576 mouse model of familial AD（FAD）that exhibits Aβaccumulation in the brain with age,we found substantial co-localization of p T555CRMP-2and dystrophic neurites.In SH-SY5Y differentiated neuronal cultures,Aβ-dependent phosphorylation of CRMP-2 at the T555 site was also elevated and this reduced the CRMP-2 association with kinesin-1.The overexpression of an unphosphorylatable form of CRMP-2 in neurons promoted the re-establishment of CRMP-2-kinesin association and axon elongation.These data suggest that Aβ-dependent phosphorylation of CRMP-2 at the T555 site may directly impair anterograde axonal transport protein function,leading to neuronal defects.
文摘The brain is a complex network system that has the capacity to support emotion, thought, action, learning and memory, and is characterized by constant activity, constant structural remodeling, and constant attempt to compensate for this remodeling. The basic insight that emerges from complex network organization is that substantively different networks can share common key organizational principles. Moreover, the interdependence of network organization and behavior has been successfully demonstrated for several specific tasks. From this viewpoint, increasing experimental/clinical observations suggest that mental disorders are neural network disorders. On one hand, single psychiatric disorders arise from multiple, multifactorial molecular and cellular structural/functional alterations spreading throughout local/global circuits leading to multifaceted and heterogeneous clinical symptoms. On the other hand, various mental diseases may share functional deficits across the same neural circuit as reflected in the overlap of symptoms throughout clinical diagnoses. An integrated framework including experimental measures and clinical observations will be necessary to formulate a coherent and comprehensive understanding of how neural connectivity mediates and constraints the phenotypic expression of psychiatric disorders.
基金Guangdong Provincial Science and Technology Foundation, No.2010B031600102,2010-170-1Guangdong Provincial Medical Science Foundation, No. A2008344Macao Science and Technology Foundation, No.026-2010-A
文摘This study examined the role of collapsin response mediator protein 1 （CRMP-1） on neurite outgrowth from rat hippocampal neurons by blocking its function using an antibody. Hippocampal neurons, cultured in vitro, were treated （blocked） using a polyclonal antibody to CRMP-1, and neurite outgrowth and cytoskeletal changes were captured using atomic force microscopy and laser confocal microscopy. Control cells, treated with normal rabbit IgG, established their characteristic morphology and had a large number of processes emerging from the soma, including numerous branches. Microtubules were clearly visible in the soma, formed an elaborate network, and were aligned in parallel arrays to form bundles which projected into neurites. After blocking with CRMP-1 antibody, the number of branches emerging from axons and dendrites significantly increased and were substantially longer, compared with control cells. However, the microtubule network nearly disappeared and only a few remnants were visible. When CRMP-1 antibody-blocked neurons were treated with the Rho inhibitor, Y27632, numerous neurites emerged from the soma, and branches were more abundant than in control neurons. Although the microtubules were not as clearly visible compared with neurons cultured in control medium, the microtubule network recovered in cells treated with Y27632, when compared with cells that were blocked by CRMP-1 antibody （but not treated with Y27632）. These results demonstrate that neurite outgrowth from hippocampal neurons can be promoted by blocking CRMP-1 with a polyclonal antibody.
基金This work was supported by the National Natural Science Foundation of China,Nos.31900691(to GWZ),81771331(to HSL)and 81971165(to WW)the National Basic Research Program of China(973 Program),No.2014CB542205(to WW)+5 种基金the Natural Science Foundation of Guangdong Province of China,No.2017A030313595(to HSL)the Science and Technology Program of Guangzhou,China,No.201707010370(to HSL)Project of Educational Commission of Guangdong Province of China,No.2018KQNCX013(to ZSJ)the Fundamental Research Funds for the Central Universities Project,China,No.21618304(to GWZ)Guangdong Provincial Key Research and Development Program“Precision Medicine and Stem Cell”Major Science and Technology Project,China,No.3242001(to WW)China Postdoctoral Science Foundation,No.2019M653292(to ZSJ).
文摘Cytoskeletal microtubule rearrangement and movement are crucial in the repair of spinal cord injury.Spastin plays an important role in the regulation of microtubule severing.Both spastin and collapsin response mediator proteins can regulate neurite growth and branching;however,whether spastin interacts with collapsin response mediator protein 3(CRMP3)during this process remains unclear,as is the mechanism by which CRMP3 participates in the repair of spinal cord injury.In this study,we used a proteomics approach to identify key proteins associated with spinal cord injury repair.We then employed liquid chromatography-mass spectrometry to identify proteins that were able to interact with glutathione S-transferase-spastin.Then,co-immunoprecipitation and staining approaches were used to evaluate potential interactions between spastin and CRMP3.Finally,we co-transfected primary hippocampal neurons with CRMP3 and spastin to evaluate their role in neurite outgrowth.Mass spectrometry identified the role of CRMP3 in the spinal cord injury repair process.Liquid chromatography-mass spectrometry pulldown assays identified three CRMP3 peptides that were able to interact with spastin.CRMP3 and spastin were co-expressed in the spinal cord and were able to interact with one another in vitro and in vivo.Lastly,CRMP3 overexpression was able to enhance the ability of spastin to promote neurite growth and branching.Therefore,our results confirm that spastin and CRMP3 play roles in spinal cord injury repair by regulating neurite growth and branching.These proteins may therefore be novel targets for spinal cord injury repair.The Institutional Animal Care and Use Committee of Jinan University,China approved this study(approval No.IACUS-20181008-03)on October 8,2018.
文摘Background： Collapsin response mediator protein-2 （CRMP2）, a multifunctional cytosolic protein highly expressed in the brain, is degraded by calpain following traumatic brain injury （TBI）, possibly inhibiting posttraumatic neurite regeneration. Lipid peroxidation （LP） is involved in triggering postinjury CRMP2 proteolysis. We examined the hypothesis that propo（bl could attenuate LP, calpain-induced CRMP2 degradation, and brain injury after TBI. Methods： A unilateral moderate controlled cortical impact injury was induced in adult male Sprague-Dawley rats. The animals were randomly divided into seven groups： Sham control group, TBI group, TB1 ＋ propofol groups （including propofol I h, 2 h, and 4 h groups）, TBI ＋ U83836E group and TBI ＋ fat emulsion group. The LP inhibitor U83836E was used as a control to identify that antioxidation partially accounts for the potential neuroprotective effects of propofol. The solvent of propofol, （＇at emulsion, was used as the vehicle control, lpsilateral cortex tissues were harvested at 24 h post-TBI. Immunofluorescent staining, Western blot analysis, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling were used to evaluate LP, calpain activity, CRMP2 proteolysis and programmed cell death. The data were statistically analyzed using one-way analysis of variance and a paired t-test. Results： Propofol and U83836E significantly ameliorated the CRMP2 proteolysis, In addition, both propofol and U83836E significantly decreased the ratio of 145-kDa cdl-spectrin breakdown products to intact 270-kDa spectrin, the 4-hydroxynonenal expression and programmed cell death in the pericontusional cortex at 24 h after TBI. There was no difference between the TB1 group and the （＇at emulsion group. Conclusions： These results demonstrate that propofol postconditioning alleviates calpain-mediated CRMP2 proteolysis and provides neuroprotective effects following moderate TBI potentially by counteracting LP and reducing calpain activation.
文摘Background： Collapsin response mediator protein-2 （CRMP2） has been shown to be involved in ischemia/hypoxia （IH） injury. We determined whether CRMP2 modulates ischemic injury in the retinal of Ocular ischemic syndrome （OIS）. This study was to explore the molecular mechanisms underlying O1S in a novel mice model. Methods： Experiments were performed oil adult male C57/BL6 mice that received bilateral internal carotid arteries ligation for 1,2, or 4 weeks. The mice received injection of calpeptin group before occlusion for 4 weeks or not. The expression of CRMP2 in the retinal was exalnined by western blotting （WB） analysis and immunohistochemical analysis （IHC）. The effects of ischemic injury on retinal were evaluated by fundus examination, fundus fluorescein angiography, electroretinogram, cell cotinting of retinal ganglion cell （RGC）, and measurement of the thickness of the retina. Results： The veins dilated after chronic ischemia. In the electroretinography, the amplitudes of a- and b-waves kept diminishing in an ischemia time-dependent manner. Moreover, the tail vein-retinal circulation time prolonged in the l- and 2-week group. In comparison, thickness of the retina decreased gradually with the ischemia time elapsed. WB analysis showed the CRMP2 and p-CRMP2 levels decreased in the 2- and 4-week groups. The results of IHC analysis were compatible with our results of WB. The loss of RGCs, decrease of the total reaction time and reduction of CRMP2 was alleviated by intravitreal injection of calpeptin. Conclusions： These results revealed that bilateral ligation of the internal carotid artery causes retinal ischemia in mice. Moreover, CRMP2 might play a pivotal role during the ischemic injury in the retina and inhibit the cleavage of CRM P2 can ameliorate the IH injury.
