Developing effective and long-term treatment strategies for rare and complex neurodegenerative diseases is challenging. One of the major roadblocks is the extensive heterogeneity among patients. This hinders understan...Developing effective and long-term treatment strategies for rare and complex neurodegenerative diseases is challenging. One of the major roadblocks is the extensive heterogeneity among patients. This hinders understanding the underlying disease-causing mechanisms and building solutions that have implications for a broad spectrum of patients. One potential solution is to develop personalized medicine approaches based on strategies that target the most prevalent cellular events that are perturbed in patients. Especially in patients with a known genetic mutation, it may be possible to understand how these mutations contribute to problems that lead to neurodegeneration. Protein–protein interaction analyses offer great advantages for revealing how proteins interact, which cellular events are primarily involved in these interactions, and how they become affected when key genes are mutated in patients. This line of investigation also suggests novel druggable targets for patients with different mutations. Here, we focus on alsin and spastin, two proteins that are identified as “causative” for amyotrophic lateral sclerosis and hereditary spastic paraplegia, respectively, when mutated. Our review analyzes the protein interactome for alsin and spastin, the canonical pathways that are primarily important for each protein domain, as well as compounds that are either Food and Drug Administration–approved or are in active clinical trials concerning the affected cellular pathways. This line of research begins to pave the way for personalized medicine approaches that are desperately needed for rare neurodegenerative diseases that are complex and heterogeneous.展开更多
Post-translational modification of spastin enables precise spatiotemporal control of its microtubule severing activity.However,the detailed mechanism by which spastin turnover is regulated in the context of neurite ou...Post-translational modification of spastin enables precise spatiotemporal control of its microtubule severing activity.However,the detailed mechanism by which spastin turnover is regulated in the context of neurite outgrowth remains unknown.Here,we found that spastin interacted with ubiquitin and was significantly degraded by K48-mediated poly-ubiquitination.Cullin3 facilitated spastin degradation and ubiquitination.RING-box protein 1,but not RING-box protein 2,acted synergistically with Cullin3 protein to regulate spastin degradation.Overexpression of Culin3 or BRX1 markedly suppressed spastin expression,and inhibited spastin-mediated microtubule severing and promotion of neurite outgrowth.Moreover,USP14 interacted directly with spastin to mediate its deubiquitination.USP14 overexpression significantly increased spastin expression and suppressed its ubiquitination and degradation.Although co-expression of spastin and USP14 did not enhance microtubule severing,it did increase neurite length in hippocampal neurons.Taken together,these findings elucidate the intricate regulatory mechanisms of spastin turnover,highlighting the roles of the Cullin-3–Ring E3 ubiquitin ligase complex and USP14 in orchestrating its ubiquitination and degradation.The dynamic interplay between these factors governs spastin stability and function,ultimately influencing microtubule dynamics and neuronal morphology.These insights shed light on potential therapeutic targets for neurodegenerative disorders associated with spastin defects.展开更多
Polyethylene glycol can connect the distal and proximal ends of an injured nerve at the cellular level through axonal fusion to avoid Wallerian degeneration of the injured distal nerve and promote peripheral nerve reg...Polyethylene glycol can connect the distal and proximal ends of an injured nerve at the cellular level through axonal fusion to avoid Wallerian degeneration of the injured distal nerve and promote peripheral nerve regeneration.However,this method can only prevent Wallerian degeneration in 10% of axons because the cytoskeleton is not repaired in a timely fashion.Reconstruction of the cytoskeletal trunk and microtubule network has been suggested to be the key for improving the efficiency of axonal fusion.As a microtubule-severing protein,spastin has been used to enhance cytoskeletal reconstruction.Therefore,we hypothesized that spastin combined with polyethylene glycol can more effectively promote peripheral nerve regeneration.A total of 120 male Sprague-Dawley rats were randomly divided into sham,suture,polyethylene glycol,and polyethylene glycol + spastin groups.In suture group rats,only traditional nerve anastomosis of the end-to-end suture was performed after transection of the sciatic nerve.In polyethylene glycol and polyethylene glycol + spastin groups,50 μL of polyethylene glycol or 25 μL of polyethylene glycol + 25 μL of spastin,respectively,were injected immediately under the epineurium of the distal suture.Sensory fiber regeneration distance,which was used to assess early nerve regeneration at 1 week after surgery,was shortest in the suture group,followed by polyethylene glycol group and greatest in the polyethylene glycol + spastin group.Behavioral assessment of motor function recovery in rats showed that limb function was restored in polyethylene glycol and polyethylene glycol + spastin groups at 8 weeks after surgery.At 1,2,4 and 8 weeks after surgery,sciatic functional index values and percentages of gastrocnemius muscle wet weight were highest in the sham group,followed by polyethylene glycol + spastin and polyethylene glycol groups,and lowest in the suture group.Masson staining was utilized to assess the morphology of muscle tissue.Morphological changes in skeletal muscle were detectable in suture,polyethylene glycol,and polyethylene glycol + spastin groups at 1,2,4,and 8 weeks after surgery.Among them,muscular atrophy of the suture group was most serious,followed by polyethylene glycol and polyethylene glycol + spastin groups.Ultrastructure of distal sciatic nerve tissue,as detected by transmission electron microscopy,showed a pattern of initial destruction,subsequent disintegration,and gradual repair in suture,polyethylene glycol,and polyethylene glycol + spastin groups at 1,2,4,and8 weeks after surgery.As time proceeded,axonal ultrastructure gradually recovered.Indeed,the polyethylene glycol + spastin group was similar to the sham group at 8 weeks after surgery.Our findings indicate that the combination of polyethylene glycol and spastin can promote peripheral nerve regeneration.Moreover,the effect of this combination was better than that of polyethylene glycol alone,and both were superior to the traditional neurorrhaphy.This study was approved by the Animal Ethics Committee of the Second Military Medical University,China(approval No.CZ20170216) on March 16,2017.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
Human immunodeficiency virus-1(HIV-1)encodes simply 15 proteins and thus depends on multiple host cellular factors for virus reproduction.Spastin,a microtubule severing protein,is an identified HIV-1 dependency factor...Human immunodeficiency virus-1(HIV-1)encodes simply 15 proteins and thus depends on multiple host cellular factors for virus reproduction.Spastin,a microtubule severing protein,is an identified HIV-1 dependency factor,but the mechanism regulating HIV-1 is unclear.Here,the study showed that knockdown of spastin inhibited the production of the intracellular HIV-1 Gag protein and new virions through enhancing Gag lysosomal degradation.Further investigation showed that increased sodium tolerance 1(IST1),the subunit of endosomal sorting complex required for transport(ESCRT),could interact with the MIT domain of spastin to regulate the intracellular Gag production.In summary,spastin is required for HIV-1 replication,while spastin-IST1 interaction facilitates virus production by regulating HIV-1 Gag intracellular trafficking and degradation.Spastin may serve as new target for HIV-1 prophylactic and therapy.展开更多
Mutation of the spastin gene is the single most common cause of pure hereditary spastic paraparesis. In patients with an unexplained sporadic upper motor neuron (UMN) syndrome, clinical distinction between primary lat...Mutation of the spastin gene is the single most common cause of pure hereditary spastic paraparesis. In patients with an unexplained sporadic upper motor neuron (UMN) syndrome, clinical distinction between primary lateral sclerosis and sporadic hereditary spastic paraparesis may be problematic. To investigate whether spastin mutations are present in patients with primary lateral sclerosis and sporadic hereditary spastic paraparesis, we screened the spastin gene in 99 Dutch patients with an unexplained, apparently sporadic, adult-onset UMN syndrome. We found 6 mutations, of which 4 were novel, in the subgroup of 47 patients with UMN symptoms restricted to the legs (13% ). Another novel spastin mutation was found in a patient with a rapidly progressive spinal and bulbar UMN syndrome that progressed to amyotrophic lateral sclerosis. In the patients with arm or bulbar UMN symptoms and slow progression, no spastin mutations were found. Our study shows that spastin mutations are a frequent cause of apparently sporadic spastic paraparesis but not of primary lateral sclerosis.展开更多
基金funded by NIH-NIA R01AG061708 (to PHO)Patrick Grange Memorial Foundation (to PHO)+1 种基金A Long Swim (to PHO)CureSPG4 Foundation (to PHO)。
文摘Developing effective and long-term treatment strategies for rare and complex neurodegenerative diseases is challenging. One of the major roadblocks is the extensive heterogeneity among patients. This hinders understanding the underlying disease-causing mechanisms and building solutions that have implications for a broad spectrum of patients. One potential solution is to develop personalized medicine approaches based on strategies that target the most prevalent cellular events that are perturbed in patients. Especially in patients with a known genetic mutation, it may be possible to understand how these mutations contribute to problems that lead to neurodegeneration. Protein–protein interaction analyses offer great advantages for revealing how proteins interact, which cellular events are primarily involved in these interactions, and how they become affected when key genes are mutated in patients. This line of investigation also suggests novel druggable targets for patients with different mutations. Here, we focus on alsin and spastin, two proteins that are identified as “causative” for amyotrophic lateral sclerosis and hereditary spastic paraplegia, respectively, when mutated. Our review analyzes the protein interactome for alsin and spastin, the canonical pathways that are primarily important for each protein domain, as well as compounds that are either Food and Drug Administration–approved or are in active clinical trials concerning the affected cellular pathways. This line of research begins to pave the way for personalized medicine approaches that are desperately needed for rare neurodegenerative diseases that are complex and heterogeneous.
基金supported by the National Natural Science Foundation of China,No.32071033(to MT)Basic and Applied Basic Research Foundation of Guangdong Province,Nos.2023A1515010140(to MT),2022A1515140169(to MT),2022A1515111096(to ZC)+3 种基金Science and Technology Project of Guangzhou,Nos.202201010015(to YL),2023A03J0790(to TJ)Basic and Applied Basic Research Foundation of Guangzhou,No.2023A04J1285(to ZC)Medical Research Foundation of Guangdong Province,No.A2023147(to ZC)Health Science and Technology Project of Guangzhou,No.20221A011039(to TJ)。
文摘Post-translational modification of spastin enables precise spatiotemporal control of its microtubule severing activity.However,the detailed mechanism by which spastin turnover is regulated in the context of neurite outgrowth remains unknown.Here,we found that spastin interacted with ubiquitin and was significantly degraded by K48-mediated poly-ubiquitination.Cullin3 facilitated spastin degradation and ubiquitination.RING-box protein 1,but not RING-box protein 2,acted synergistically with Cullin3 protein to regulate spastin degradation.Overexpression of Culin3 or BRX1 markedly suppressed spastin expression,and inhibited spastin-mediated microtubule severing and promotion of neurite outgrowth.Moreover,USP14 interacted directly with spastin to mediate its deubiquitination.USP14 overexpression significantly increased spastin expression and suppressed its ubiquitination and degradation.Although co-expression of spastin and USP14 did not enhance microtubule severing,it did increase neurite length in hippocampal neurons.Taken together,these findings elucidate the intricate regulatory mechanisms of spastin turnover,highlighting the roles of the Cullin-3–Ring E3 ubiquitin ligase complex and USP14 in orchestrating its ubiquitination and degradation.The dynamic interplay between these factors governs spastin stability and function,ultimately influencing microtubule dynamics and neuronal morphology.These insights shed light on potential therapeutic targets for neurodegenerative disorders associated with spastin defects.
基金supported by the National Natural Science Foundation of China,No.81772327(to HDL)the Shuguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission,China,No.15SG34(to HDL)
文摘Polyethylene glycol can connect the distal and proximal ends of an injured nerve at the cellular level through axonal fusion to avoid Wallerian degeneration of the injured distal nerve and promote peripheral nerve regeneration.However,this method can only prevent Wallerian degeneration in 10% of axons because the cytoskeleton is not repaired in a timely fashion.Reconstruction of the cytoskeletal trunk and microtubule network has been suggested to be the key for improving the efficiency of axonal fusion.As a microtubule-severing protein,spastin has been used to enhance cytoskeletal reconstruction.Therefore,we hypothesized that spastin combined with polyethylene glycol can more effectively promote peripheral nerve regeneration.A total of 120 male Sprague-Dawley rats were randomly divided into sham,suture,polyethylene glycol,and polyethylene glycol + spastin groups.In suture group rats,only traditional nerve anastomosis of the end-to-end suture was performed after transection of the sciatic nerve.In polyethylene glycol and polyethylene glycol + spastin groups,50 μL of polyethylene glycol or 25 μL of polyethylene glycol + 25 μL of spastin,respectively,were injected immediately under the epineurium of the distal suture.Sensory fiber regeneration distance,which was used to assess early nerve regeneration at 1 week after surgery,was shortest in the suture group,followed by polyethylene glycol group and greatest in the polyethylene glycol + spastin group.Behavioral assessment of motor function recovery in rats showed that limb function was restored in polyethylene glycol and polyethylene glycol + spastin groups at 8 weeks after surgery.At 1,2,4 and 8 weeks after surgery,sciatic functional index values and percentages of gastrocnemius muscle wet weight were highest in the sham group,followed by polyethylene glycol + spastin and polyethylene glycol groups,and lowest in the suture group.Masson staining was utilized to assess the morphology of muscle tissue.Morphological changes in skeletal muscle were detectable in suture,polyethylene glycol,and polyethylene glycol + spastin groups at 1,2,4,and 8 weeks after surgery.Among them,muscular atrophy of the suture group was most serious,followed by polyethylene glycol and polyethylene glycol + spastin groups.Ultrastructure of distal sciatic nerve tissue,as detected by transmission electron microscopy,showed a pattern of initial destruction,subsequent disintegration,and gradual repair in suture,polyethylene glycol,and polyethylene glycol + spastin groups at 1,2,4,and8 weeks after surgery.As time proceeded,axonal ultrastructure gradually recovered.Indeed,the polyethylene glycol + spastin group was similar to the sham group at 8 weeks after surgery.Our findings indicate that the combination of polyethylene glycol and spastin can promote peripheral nerve regeneration.Moreover,the effect of this combination was better than that of polyethylene glycol alone,and both were superior to the traditional neurorrhaphy.This study was approved by the Animal Ethics Committee of the Second Military Medical University,China(approval No.CZ20170216) on March 16,2017.
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.
基金We greatly appreciate Prof.Charles Wood(University of Nebraska,Lincoln,USA)for the gift of the infectious molecular clones(pNL4.3,pNL4.3ΔEnvEGFP,and pVSV-G).the National Natural Science Foundation of China(81571987)Natural Science Foundation of Tianjin Municipal Science and Technology Commission(20JCQNJC01750,21JCQNJC01600).
文摘Human immunodeficiency virus-1(HIV-1)encodes simply 15 proteins and thus depends on multiple host cellular factors for virus reproduction.Spastin,a microtubule severing protein,is an identified HIV-1 dependency factor,but the mechanism regulating HIV-1 is unclear.Here,the study showed that knockdown of spastin inhibited the production of the intracellular HIV-1 Gag protein and new virions through enhancing Gag lysosomal degradation.Further investigation showed that increased sodium tolerance 1(IST1),the subunit of endosomal sorting complex required for transport(ESCRT),could interact with the MIT domain of spastin to regulate the intracellular Gag production.In summary,spastin is required for HIV-1 replication,while spastin-IST1 interaction facilitates virus production by regulating HIV-1 Gag intracellular trafficking and degradation.Spastin may serve as new target for HIV-1 prophylactic and therapy.
文摘Mutation of the spastin gene is the single most common cause of pure hereditary spastic paraparesis. In patients with an unexplained sporadic upper motor neuron (UMN) syndrome, clinical distinction between primary lateral sclerosis and sporadic hereditary spastic paraparesis may be problematic. To investigate whether spastin mutations are present in patients with primary lateral sclerosis and sporadic hereditary spastic paraparesis, we screened the spastin gene in 99 Dutch patients with an unexplained, apparently sporadic, adult-onset UMN syndrome. We found 6 mutations, of which 4 were novel, in the subgroup of 47 patients with UMN symptoms restricted to the legs (13% ). Another novel spastin mutation was found in a patient with a rapidly progressive spinal and bulbar UMN syndrome that progressed to amyotrophic lateral sclerosis. In the patients with arm or bulbar UMN symptoms and slow progression, no spastin mutations were found. Our study shows that spastin mutations are a frequent cause of apparently sporadic spastic paraparesis but not of primary lateral sclerosis.
