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
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
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： Rho GTPase family members have been shown to participate in neurite growth by regulating the neuronal cytoskeleton. However, there are very few reports of developmental roles of signaling molecules relate...BACKGROUND： Rho GTPase family members have been shown to participate in neurite growth by regulating the neuronal cytoskeleton. However, there are very few reports of developmental roles of signaling molecules related to Rho GTPases. OBJECTIVE： To investigate messenger ribonucleic acid mRNA expression of signaling molecules associated with Rho GTPases, including Rho-A, Rac-1, collapsin response mediator protein 1 （CRMP-1）, and tubulin 133 （Tub/33） during rat hippocampus development. DESIGN, TIME AND SETTING- A non-randomized, controlled, animal experiment, based on different developmental stages of the rat hippocampus, was performed at the Guangdong Key Laboratory of Tissue Construction and Detection, Institute of Clinical Anatomy, Southern Medical University between December 2005 and July 2007. MATERIALS： Trizol reagent was purchased from Invitrogen, USA. RNA PCR kit （AMV） Ver 3.0 and 150 bp DNA Ladder Marker were purchased from TaKaRa, Japan. Unless otherwise specified, all other reagents were purchased from Sigma-Aldrich, USA. METHODS： Twenty-five Sprague Dawley rats were assigned to five groups （n = 5） according to developmental stages： embryonic （embryonic 15 days）, neonatal （postnatal 5 days）, juvenile （postnatal 1 month）, adult （postnatal 3 months）, and senile （postnatal 18 months）. MAIN OUTCOME MEASURES： Detection of mRNA expression of Rho-A, Rac-1, CRMP-1, and Tub β3 during various hippocampal developmental stages by reverse-transcription polymerase chain reaction. RESULTS： Hippocampal mRNA expression of Rho-A, as well as Rac-1, reached peak levels at embryonic, juvenile, and senile stages, and was relatively less during neonatal and adult stages. mRNA expression of Rac-1 was greater than Rho-A during each hippocampal developmental stage. CRMP-1 mRNA expression levels were as follows： embryonic 〉 neonatal 〉 juvenile 〉 adult 〈 senile, while Tubβ3 mRNA expression was embryonic 〉 neonatal 〉 juvenile 〉 adult = senile. CONCLUSION： Rho-A and Rac-1 shared similar expression profiles, which demonstrated similar variations during the entire rat hippocampus developmental process. However, Rac-1 mRNA expression remained greater than Rho-A. Both CRMP-1 and Tubβ3 mRNA expression profiles gradually declined during hippocampal development from embryonic to adult stages. Tubβ3 mRNA expression arrested during the adult stage, and CRMP-1 mRNA expression increased during the senile stage.展开更多
Axonal growth inhibitors are released during traumatic injuries to the adult mammalian central nervous system, including after spinal cord injury. These molecules accumulate at the injury site and form a highly inhibi...Axonal growth inhibitors are released during traumatic injuries to the adult mammalian central nervous system, including after spinal cord injury. These molecules accumulate at the injury site and form a highly inhibitory environment for axonal regeneration. Among these inhibitory molecules, myelinassociated inhibitors, including neurite outgrowth inhibitor A, oligodendrocyte myelin glycoprotein, myelin-associated glycoprotein, chondroitin sulfate proteoglycans and repulsive guidance molecule A are of particular importance. Due to their inhibitory nature, they represent exciting molecular targets to study axonal inhibition and regeneration after central injuries. These molecules are mainly produced by neurons, oligodendrocytes, and astrocytes within the scar and in its immediate vicinity. They exert their effects by binding to specific receptors, localized in the membranes of neurons. Receptors for these inhibitory cues include Nogo receptor 1, leucine-rich repeat, and Ig domain containing 1 and p75 neurotrophin receptor/tumor necrosis factor receptor superfamily member 19(that form a receptor complex that binds all myelin-associated inhibitors), and also paired immunoglobulin-like receptor B. Chondroitin sulfate proteoglycans and repulsive guidance molecule A bind to Nogo receptor 1, Nogo receptor 3, receptor protein tyrosine phosphatase σ and leucocyte common antigen related phosphatase, and neogenin, respectively. Once activated, these receptors initiate downstream signaling pathways, the most common amongst them being the Rho A/ROCK signaling pathway. These signaling cascades result in actin depolymerization, neurite outgrowth inhibition, and failure to regenerate after spinal cord injury. Currently, there are no approved pharmacological treatments to overcome spinal cord injuries other than physical rehabilitation and management of the array of symptoms brought on by spinal cord injuries. However, several novel therapies aiming to modulate these inhibitory proteins and/or their receptors are under investigation in ongoing clinical trials. Investigation has also been demonstrating that combinatorial therapies of growth inhibitors with other therapies, such as growth factors or stem-cell therapies, produce stronger results and their potential application in the clinics opens new venues in spinal cord injury treatment.展开更多
Brain-specific loss of a microtubule-binding protein collapsin response mediator protein-2(CRMP2)in the mouse recapitulates many schizophrenia-like behaviors of human patients,possibly resulting from associated develo...Brain-specific loss of a microtubule-binding protein collapsin response mediator protein-2(CRMP2)in the mouse recapitulates many schizophrenia-like behaviors of human patients,possibly resulting from associated developmental deficits in neuronal differentiation,path-finding,and synapse formation.However,it is still unclear how the Crmp2 loss affects neuronal circuit function and plasticity.By conducting in vivo and ex vivo electrophysiological recording in the mouse primary visual cortex(V1),we reveal that CRMP2 exerts a key regulation on the timing of postnatal critical period(CP)for experience-dependent circuit plasticity of sensory cortex.In the developing V1,the Crmp2 deficiency induces not only a delayed maturation of visual tuning functions but also a precocious CP for visual input-induced ocular dominance plasticity and its induction activity–coincident binocular inputs right after eye-opening.Mechanistically,the Crmp2 deficiency accelerates the maturation process of cortical inhibitory transmission and subsequently promotes an early emergence of balanced excitatory-inhibitory cortical circuits during the postnatal development.Moreover,the precocious CP plasticity results in deteriorated binocular depth perception in adulthood.Thus,these findings suggest that the Crmp2 deficiency dysregulates the timing of CP for experience-dependent refinement of circuit connections and further leads to impaired sensory perception in later life.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.
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.
基金Supported by:the National Basic Research Program of China(973 Program),No. 2007CB512705the Natural Science Foundation of Guangdong Province,No. 8451063201000193
文摘BACKGROUND： Rho GTPase family members have been shown to participate in neurite growth by regulating the neuronal cytoskeleton. However, there are very few reports of developmental roles of signaling molecules related to Rho GTPases. OBJECTIVE： To investigate messenger ribonucleic acid mRNA expression of signaling molecules associated with Rho GTPases, including Rho-A, Rac-1, collapsin response mediator protein 1 （CRMP-1）, and tubulin 133 （Tub/33） during rat hippocampus development. DESIGN, TIME AND SETTING- A non-randomized, controlled, animal experiment, based on different developmental stages of the rat hippocampus, was performed at the Guangdong Key Laboratory of Tissue Construction and Detection, Institute of Clinical Anatomy, Southern Medical University between December 2005 and July 2007. MATERIALS： Trizol reagent was purchased from Invitrogen, USA. RNA PCR kit （AMV） Ver 3.0 and 150 bp DNA Ladder Marker were purchased from TaKaRa, Japan. Unless otherwise specified, all other reagents were purchased from Sigma-Aldrich, USA. METHODS： Twenty-five Sprague Dawley rats were assigned to five groups （n = 5） according to developmental stages： embryonic （embryonic 15 days）, neonatal （postnatal 5 days）, juvenile （postnatal 1 month）, adult （postnatal 3 months）, and senile （postnatal 18 months）. MAIN OUTCOME MEASURES： Detection of mRNA expression of Rho-A, Rac-1, CRMP-1, and Tub β3 during various hippocampal developmental stages by reverse-transcription polymerase chain reaction. RESULTS： Hippocampal mRNA expression of Rho-A, as well as Rac-1, reached peak levels at embryonic, juvenile, and senile stages, and was relatively less during neonatal and adult stages. mRNA expression of Rac-1 was greater than Rho-A during each hippocampal developmental stage. CRMP-1 mRNA expression levels were as follows： embryonic 〉 neonatal 〉 juvenile 〉 adult 〈 senile, while Tubβ3 mRNA expression was embryonic 〉 neonatal 〉 juvenile 〉 adult = senile. CONCLUSION： Rho-A and Rac-1 shared similar expression profiles, which demonstrated similar variations during the entire rat hippocampus developmental process. However, Rac-1 mRNA expression remained greater than Rho-A. Both CRMP-1 and Tubβ3 mRNA expression profiles gradually declined during hippocampal development from embryonic to adult stages. Tubβ3 mRNA expression arrested during the adult stage, and CRMP-1 mRNA expression increased during the senile stage.
基金a Ph D fellowship by FCT-Fundacao para a Ciência Tecnologia (SFRH/BD/135868/2018)(to SSC)。
文摘Axonal growth inhibitors are released during traumatic injuries to the adult mammalian central nervous system, including after spinal cord injury. These molecules accumulate at the injury site and form a highly inhibitory environment for axonal regeneration. Among these inhibitory molecules, myelinassociated inhibitors, including neurite outgrowth inhibitor A, oligodendrocyte myelin glycoprotein, myelin-associated glycoprotein, chondroitin sulfate proteoglycans and repulsive guidance molecule A are of particular importance. Due to their inhibitory nature, they represent exciting molecular targets to study axonal inhibition and regeneration after central injuries. These molecules are mainly produced by neurons, oligodendrocytes, and astrocytes within the scar and in its immediate vicinity. They exert their effects by binding to specific receptors, localized in the membranes of neurons. Receptors for these inhibitory cues include Nogo receptor 1, leucine-rich repeat, and Ig domain containing 1 and p75 neurotrophin receptor/tumor necrosis factor receptor superfamily member 19(that form a receptor complex that binds all myelin-associated inhibitors), and also paired immunoglobulin-like receptor B. Chondroitin sulfate proteoglycans and repulsive guidance molecule A bind to Nogo receptor 1, Nogo receptor 3, receptor protein tyrosine phosphatase σ and leucocyte common antigen related phosphatase, and neogenin, respectively. Once activated, these receptors initiate downstream signaling pathways, the most common amongst them being the Rho A/ROCK signaling pathway. These signaling cascades result in actin depolymerization, neurite outgrowth inhibition, and failure to regenerate after spinal cord injury. Currently, there are no approved pharmacological treatments to overcome spinal cord injuries other than physical rehabilitation and management of the array of symptoms brought on by spinal cord injuries. However, several novel therapies aiming to modulate these inhibitory proteins and/or their receptors are under investigation in ongoing clinical trials. Investigation has also been demonstrating that combinatorial therapies of growth inhibitors with other therapies, such as growth factors or stem-cell therapies, produce stronger results and their potential application in the clinics opens new venues in spinal cord injury treatment.
基金the National Natural Science Foundation of China(32071025,31921002,and 31730108)the Beijing Municipal Science&Technology Commission(Z181100001518001)+1 种基金the Interdisciplinary Research Fund of Beijing Normal Universitythe Strategic Priority Research Program and Innovation Program of the Chinese Academy of Sciences(XDB32020100)。
文摘Brain-specific loss of a microtubule-binding protein collapsin response mediator protein-2(CRMP2)in the mouse recapitulates many schizophrenia-like behaviors of human patients,possibly resulting from associated developmental deficits in neuronal differentiation,path-finding,and synapse formation.However,it is still unclear how the Crmp2 loss affects neuronal circuit function and plasticity.By conducting in vivo and ex vivo electrophysiological recording in the mouse primary visual cortex(V1),we reveal that CRMP2 exerts a key regulation on the timing of postnatal critical period(CP)for experience-dependent circuit plasticity of sensory cortex.In the developing V1,the Crmp2 deficiency induces not only a delayed maturation of visual tuning functions but also a precocious CP for visual input-induced ocular dominance plasticity and its induction activity–coincident binocular inputs right after eye-opening.Mechanistically,the Crmp2 deficiency accelerates the maturation process of cortical inhibitory transmission and subsequently promotes an early emergence of balanced excitatory-inhibitory cortical circuits during the postnatal development.Moreover,the precocious CP plasticity results in deteriorated binocular depth perception in adulthood.Thus,these findings suggest that the Crmp2 deficiency dysregulates the timing of CP for experience-dependent refinement of circuit connections and further leads to impaired sensory perception in later life.
