Background Atg9-containing vesicles are enriched in synapses and undergo cycles of exo-and endocytosis similarly to synaptic vesicles,thereby linking presynaptic autophagy to neuronal activity.Dysfunction of presynapt...Background Atg9-containing vesicles are enriched in synapses and undergo cycles of exo-and endocytosis similarly to synaptic vesicles,thereby linking presynaptic autophagy to neuronal activity.Dysfunction of presynaptic autophagy is a pathophysiological mechanism in motoneuron disease(MND),which leads to impaired synaptic integrity and function.Here,we asked whether boosting neuronal activity by physical exercise modulates the cellular and motor phenotypes of Plekhg5-deficient mice,an MND model with defective presynaptic autophagy.Methods To characterize the vesicle accumulations in Plekhg5-deficient mice,we performed immunohistochemical staining,electron microscopy,and super-resolution imaging.Following voluntary running wheel exercise,we quantified the histopathological changes within the spinal cord and at neuromuscular junctions using an unbiased machine-learning approach.Additionally,we analyzed the motor performance of the animals by measuring their grip strength.To assess changes in the autophagic flux upon physical exercise in vivo,we utilized mRFP-GFP-LC3 expressing mice.The presence of Atg9-containing vesicle clusters in SOD1G93A was analyzed to examine the relevance of this pathological feature in a second MND model.Results We found marked accumulations of Atg9-containing vesicles at presynaptic sites of Plekhg5-deficient mice,which could be cleared by four weeks of voluntary running wheel exercise in young but surprisingly not in aged Plekhg5-deficient mice.However,physical exercise in aged mice led to synaptic vesicle sorting into the Atg9-containing vesicle accumulations without their removal.In line with these findings,short-term voluntary exercise triggered motoneuron autophagy in young but not old mice.Pointing to a broader role of Atg9-containing vesicles in the pathophysiology of MND,we also found Atg9-containing vesicle accumulations in SOD1G93A mice,a well-established ALS model.Strikingly,physical exercise in presymptomatic SOD1G93A mice resulted in a reduction of the vesicle accumulations.Conclusions Our data highlight the essential role of Atg9 in presynaptic autophagy and suggest that boosting autophagy by physical exercise provides a tool to maintain presynaptic function at the early but not late stages of Plekhg5-associated MND and possibly amyotrophic lateral sclerosis.展开更多
基金supported by the DFG grant DFG LU 2347/3-1.The JEOL JEM-2100 transmission electron microscope is funded by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)-218894163VC and KGH were supported by a grant of the Interdisciplinary Center of Clinical Research(IZKF)of the Medical Facility of Wurzburg(grant number F-N-439)Super-resolution microscopy was further supported by the IZKF(Grant No.Z-12 to KGH)and the Core Unit Fluorescence Imaging of the Medical Faculty of the JMU.
文摘Background Atg9-containing vesicles are enriched in synapses and undergo cycles of exo-and endocytosis similarly to synaptic vesicles,thereby linking presynaptic autophagy to neuronal activity.Dysfunction of presynaptic autophagy is a pathophysiological mechanism in motoneuron disease(MND),which leads to impaired synaptic integrity and function.Here,we asked whether boosting neuronal activity by physical exercise modulates the cellular and motor phenotypes of Plekhg5-deficient mice,an MND model with defective presynaptic autophagy.Methods To characterize the vesicle accumulations in Plekhg5-deficient mice,we performed immunohistochemical staining,electron microscopy,and super-resolution imaging.Following voluntary running wheel exercise,we quantified the histopathological changes within the spinal cord and at neuromuscular junctions using an unbiased machine-learning approach.Additionally,we analyzed the motor performance of the animals by measuring their grip strength.To assess changes in the autophagic flux upon physical exercise in vivo,we utilized mRFP-GFP-LC3 expressing mice.The presence of Atg9-containing vesicle clusters in SOD1G93A was analyzed to examine the relevance of this pathological feature in a second MND model.Results We found marked accumulations of Atg9-containing vesicles at presynaptic sites of Plekhg5-deficient mice,which could be cleared by four weeks of voluntary running wheel exercise in young but surprisingly not in aged Plekhg5-deficient mice.However,physical exercise in aged mice led to synaptic vesicle sorting into the Atg9-containing vesicle accumulations without their removal.In line with these findings,short-term voluntary exercise triggered motoneuron autophagy in young but not old mice.Pointing to a broader role of Atg9-containing vesicles in the pathophysiology of MND,we also found Atg9-containing vesicle accumulations in SOD1G93A mice,a well-established ALS model.Strikingly,physical exercise in presymptomatic SOD1G93A mice resulted in a reduction of the vesicle accumulations.Conclusions Our data highlight the essential role of Atg9 in presynaptic autophagy and suggest that boosting autophagy by physical exercise provides a tool to maintain presynaptic function at the early but not late stages of Plekhg5-associated MND and possibly amyotrophic lateral sclerosis.
