Cerebral ischemia remains the top causes of mortality and disability worldwide.The pathological mechanisms underlying ischemic brain injury are not fully illustrated.Cerebral ischemia induces massive mitochondrial dam...Cerebral ischemia remains the top causes of mortality and disability worldwide.The pathological mechanisms underlying ischemic brain injury are not fully illustrated.Cerebral ischemia induces massive mitochondrial damage,which are cleared by mitochondrial autophagy(mitophagy).Our previous studies indicated mitophagy is critical for neuronal survival after ischemic injury,thus raise the conception of rescuing ischemic brain injury by regulating neuronal mitophagy.We further explored the molecular mechanisms underlying ischemia-induced mitophagy,in particular with the regulations of Nix.Our ongoing study focuses on the spatial features of neuronal mitophagy after ischemic insult.Distinct from other cell types,neurons are highlypolarized cells with elaborate dendrites and axons,in which extensive mitochondrial are distributed.Despite the facts that neuronal mitophagy is promptly activated by ischemia,the intracellular locations of mitophagy in neuron,however are largely unknown.The primary cultured mice cortical neurons were treated with oxygen-glucose deprivation(OGD),which mimics ischemia.We confirmed mitochondrial loss both in neuronal cell bodies and axons.However,we found that axonal mitochondria elimination was not compromised in autophagy deficient neurons,suggesting the absence of direct mitophagy in axons.We unexpectedly found that axonal mitochondria underwent a prompt retrograde transportation upon reperfusion while the anterograde mitochondrial mobility was irreversible lost after OGD.We labelled the axonal mitochondria and found they were degraded by autophagic machin-ery in neuronal soma.Inhibition of axonal mitochondria retrograde transportation by expression Syntaphilin,an anchoring protein,blocked neuronal mitophagy.Conversely,chimeric expression of a fusion protein targets mitochondria to dynein complex reinforced mitochondrial retrograde transport and enhanced mitophagy.These evidences indicated a somatic autophagy of axonal mitochondria in ischemic neurons.This pattern may facilitate neuronal mitophagy in the scenario of acute ischemia.Taken together,we found that axonal mitochondria are not cleared locally in axons but are retrograde transported to neuronal soma for mitophagy in ischemic neurons.The present study identified a novel pattern for neurons to eliminate damaged mitochondria and provided the missing link between mitochondrial mobility and mitophagy in ischemic neurons.展开更多
OBJECTIVE The proteasome inhibitor bortezomib(BTZ)is a first-line anti-multi⁃ple myeloma drug.BTZ-induced peripheral neu⁃ropathy(BIPN)is a main adverse effect that char⁃acterized by neuropathic pain.There is still no ...OBJECTIVE The proteasome inhibitor bortezomib(BTZ)is a first-line anti-multi⁃ple myeloma drug.BTZ-induced peripheral neu⁃ropathy(BIPN)is a main adverse effect that char⁃acterized by neuropathic pain.There is still no strategy to prevent or treat BIPN,attributed to the unidentified mechanisms underlying BIPN.Previous studies suggested that BTZ impairs Schwann cells and thus leads to axonal demye⁃lination,whereas it remained not fully understood how BTZ cause Schwann cell death.It was observed that BTZ upregulates the autophagy marker LC3-Ⅱprotein in Schwann cells.However,it remains unclear whether BTZ causes autopha⁃gy-lysosome dysfunction in Schwann cells.METHODS The male C57BL/6 mice were intra⁃venous injection of BTZ(1 mg·kg-1 per day,twice weekly for a total of 4 weeks).The paw withdraw⁃al latency was tested by the Von Frey test and Hargreaves test to reflect the neuropathic pain.The conduction velocity and the action potential amplitude of the tail nerve were tested by neuro⁃physiological assessment to reflect peripheral nerve function.The histomorphology of the sciat⁃ic nerves was detected by immunofluorescence and transmission electron microscopy to reflect the demyelination and axonal degeneration.The RSC96 cells,the Schwann cell-like immortal cells,were cultured and exposed to BTZ.The lysosomal function was determined by Lyso⁃Tracker and DQ-BSA staining.Autophagy-relat⁃ed proteins,including p62 and LC3,and lysosom⁃al hydrolase cathepsin B were determined by Western blotting.RESULTS①BTZ induced mechano-allodynia,neurological conduction abnormalities of the tail nerve,demyelination and axonal degeneration of the sciatic nerves.②BTZ caused lysosomal dysfunction,resulting in the blockade of autophagy flux in Schwann cells and sciatic nerves.③The lysosomal activator Torin1 reversed lysosomal dysfunction caused by BTZ in Schwann cells.④Torin1 improved BTZ-induced mechano-allodynia and demyelination of sciatic nerves.CONCLUSION BTZ led to lyso⁃somal dysfunction in Schwann cells and contrib⁃uted to BIPN.Lysosomal activation could be a promising strategy for BIPN intervention.展开更多
OBJECTIVE Progressive isch⁃emic stroke is characterized by aggravation of neurological dysfunction and poor prognosis.Neuroinflammation is involved in the pathological process of cerebral ischemia.Inflammasomes-activa...OBJECTIVE Progressive isch⁃emic stroke is characterized by aggravation of neurological dysfunction and poor prognosis.Neuroinflammation is involved in the pathological process of cerebral ischemia.Inflammasomes-activated caspase-1 has thus been considered a promising target for stroke therapy.However,it remains not fully understood how caspase-1 ag⁃gravates progressive functional impairment.We previously identified a novel caspase-1 inhibitor CZL-80,the present study is to explore whether CZL-80 protects against progressive ischemic stroke.METHODS Male C57/BL6 mice and cas⁃pase-1-/-mice were subjected to photothrombotic(PT)-induced cerebral ischemia.CZL-80 was in⁃traperitoneally injected daily during 1-7 d,1-4 d,4-7 d after PT.The grid-walking task and the cyl⁃inder task were used to determine the motor function.RESULTS Mice developed primary and the secondary neurological dysfunction at 1 d and 4-7 d after PT onset.The activation of cas⁃pase-1 peaked at 7 d after ischemic stroke and caspase-1 was mainly derived from activated microglia.Treatment with CZL-80(30 mg·kg-1)during 1-7 d significantly improved motor func⁃tion.Administration of CZL-80 during 1-4 d could not ameliorate motor function loss while administration during 4-7 d after PT onset signifi⁃cantly reduced foot faults and forelimb symme⁃try.Remarkably,treatment with CZL-80 during 4-7 d showed no significant difference in efficacy compared with the its administration during 1-7 d,which indicated a key therapeutic window.More⁃over,the neuroprotective effect of CZL-80 during 4-7 d was available at least until 43 d after isch⁃emic stroke,indicating CZL-80 can improve the long-term neurological function after cerebral ischemia.Furthermore,administration of CZL-80(30 mg·kg-1)during 4-7 d after PT onset in cas⁃pase-1-/-mice failed to improve the motor func⁃tion,which suggested that the neuroprotective effect of CZL-80 was caspase-1-dependent.The results showed that CZL-80 did not inhibit the expression of GSDMD and failed to reduce neu⁃ronal loss after ischemia.These results indicated the effect of CZL-80 was not attributable to inhib⁃it pyroptosis.We further found that CZL-80 signif⁃icantly reduced the number of activated microglia in the peri-infarct brain cortex after ischemic stroke,which might be involved in its neuropro⁃tective effect.CONCLUSION CZL-80,a novel caspase-1 inhibitor,improved motor function after progressive ischemic stroke in mice.The effective therapeutic window of CZL-80 would be 4-7 d after ischemia,when the secondary neuro⁃logical dysfunction occurred.Therefore,the inter⁃vention by targeting caspase-1 in this window phase provides a novel strategy for the function⁃al recovery of stroke survivors.展开更多
OBJECTIVE Dysfunction of the dopaminergic(DA)neurons is implicated in the pathogenesis of bipolar disorder(BPD).Hista⁃mine receptor 2(Hrh2)is highly expressed in DA neurons,and its antagonists have been reported to in...OBJECTIVE Dysfunction of the dopaminergic(DA)neurons is implicated in the pathogenesis of bipolar disorder(BPD).Hista⁃mine receptor 2(Hrh2)is highly expressed in DA neurons,and its antagonists have been reported to induce mania phase of BPD.However,whether Hrh2 on DA neurons contributes to BPD patho⁃genesis is unclear.The present study aims to explore the role of hrh2 on DA neurons in the pathology of BPD.METHODS AAV-FLEX-shHrh2 was injected into a targeted brain area of DAT-Cre mice,leading to a selective brain-regional loss of Hrh2 on DA neurons.A series of behavior tests were used to measure the sponta⁃neous activity,anxiety and depression level of Hrh2-deficient mice.RESULTS①In the open field test and home-cage activity test,Hrh2-defi⁃cient mice displayed increased spontaneous activity.②Hrh2-deficient mice showed reduced depression level in the tail suspension test,forced swimming test and sucrose preference test.③The anxiety level of Hrh2-deficient mice was decreased in the open field test.CONCLU⁃SION Hrh2 on DA neurons is closely related with mania-like behavior.展开更多
OBJECTIVE Chronic cerebral hy⁃poperfusion can lead to progressive demyelin⁃ation and ischemic vascular dementia,yet there are no effective treatments.METHODS Magnetic resonance imaging was employed in patients with wh...OBJECTIVE Chronic cerebral hy⁃poperfusion can lead to progressive demyelin⁃ation and ischemic vascular dementia,yet there are no effective treatments.METHODS Magnetic resonance imaging was employed in patients with white matter damage,and optogenetics and skin stroking were exerted to activate glutamater⁃gic neurons in the somatosensory cortex in a clas⁃sical mouse model of ischemia vascular dementia.RESULTS White matter damage was correlated with disrupted cortical structure from MRI results.In a mouse model,activating glutamatergic neu⁃rons in the somatosensory cortex promotes prolif⁃eration of OPCs and remyelination to rescue cog⁃nitive impairment after chronic cerebral hypoper⁃fusion.Such therapeutic action was limited to stimulation with moderate intensity at the upper layers of the cortex,but was achieved over a wide time window after ischemia.Mechanistically,enhanced glutamatergic neuron-OPC functional synaptic connections are required for protection from activation of cortical glutamatergic neurons.Finally,skin stroking activation of the somatosen⁃sory cortex,an easier approach for clinical trans⁃lation,promoted OPC proliferation and remyelin⁃ation as well as cognitive recovery after cerebral hypoperfusion.CONCLUSION Activation of gluta⁃matergic neurons in the somatosensory cortex may serve as novel approaches for treating isch⁃emic vascular dementia through precise modula⁃tion of glutamatergic neuron-OPC circuits.展开更多
基金National Natural Science Foundation of China(81573406,81773703).
文摘Cerebral ischemia remains the top causes of mortality and disability worldwide.The pathological mechanisms underlying ischemic brain injury are not fully illustrated.Cerebral ischemia induces massive mitochondrial damage,which are cleared by mitochondrial autophagy(mitophagy).Our previous studies indicated mitophagy is critical for neuronal survival after ischemic injury,thus raise the conception of rescuing ischemic brain injury by regulating neuronal mitophagy.We further explored the molecular mechanisms underlying ischemia-induced mitophagy,in particular with the regulations of Nix.Our ongoing study focuses on the spatial features of neuronal mitophagy after ischemic insult.Distinct from other cell types,neurons are highlypolarized cells with elaborate dendrites and axons,in which extensive mitochondrial are distributed.Despite the facts that neuronal mitophagy is promptly activated by ischemia,the intracellular locations of mitophagy in neuron,however are largely unknown.The primary cultured mice cortical neurons were treated with oxygen-glucose deprivation(OGD),which mimics ischemia.We confirmed mitochondrial loss both in neuronal cell bodies and axons.However,we found that axonal mitochondria elimination was not compromised in autophagy deficient neurons,suggesting the absence of direct mitophagy in axons.We unexpectedly found that axonal mitochondria underwent a prompt retrograde transportation upon reperfusion while the anterograde mitochondrial mobility was irreversible lost after OGD.We labelled the axonal mitochondria and found they were degraded by autophagic machin-ery in neuronal soma.Inhibition of axonal mitochondria retrograde transportation by expression Syntaphilin,an anchoring protein,blocked neuronal mitophagy.Conversely,chimeric expression of a fusion protein targets mitochondria to dynein complex reinforced mitochondrial retrograde transport and enhanced mitophagy.These evidences indicated a somatic autophagy of axonal mitochondria in ischemic neurons.This pattern may facilitate neuronal mitophagy in the scenario of acute ischemia.Taken together,we found that axonal mitochondria are not cleared locally in axons but are retrograde transported to neuronal soma for mitophagy in ischemic neurons.The present study identified a novel pattern for neurons to eliminate damaged mitochondria and provided the missing link between mitochondrial mobility and mitophagy in ischemic neurons.
文摘OBJECTIVE The proteasome inhibitor bortezomib(BTZ)is a first-line anti-multi⁃ple myeloma drug.BTZ-induced peripheral neu⁃ropathy(BIPN)is a main adverse effect that char⁃acterized by neuropathic pain.There is still no strategy to prevent or treat BIPN,attributed to the unidentified mechanisms underlying BIPN.Previous studies suggested that BTZ impairs Schwann cells and thus leads to axonal demye⁃lination,whereas it remained not fully understood how BTZ cause Schwann cell death.It was observed that BTZ upregulates the autophagy marker LC3-Ⅱprotein in Schwann cells.However,it remains unclear whether BTZ causes autopha⁃gy-lysosome dysfunction in Schwann cells.METHODS The male C57BL/6 mice were intra⁃venous injection of BTZ(1 mg·kg-1 per day,twice weekly for a total of 4 weeks).The paw withdraw⁃al latency was tested by the Von Frey test and Hargreaves test to reflect the neuropathic pain.The conduction velocity and the action potential amplitude of the tail nerve were tested by neuro⁃physiological assessment to reflect peripheral nerve function.The histomorphology of the sciat⁃ic nerves was detected by immunofluorescence and transmission electron microscopy to reflect the demyelination and axonal degeneration.The RSC96 cells,the Schwann cell-like immortal cells,were cultured and exposed to BTZ.The lysosomal function was determined by Lyso⁃Tracker and DQ-BSA staining.Autophagy-relat⁃ed proteins,including p62 and LC3,and lysosom⁃al hydrolase cathepsin B were determined by Western blotting.RESULTS①BTZ induced mechano-allodynia,neurological conduction abnormalities of the tail nerve,demyelination and axonal degeneration of the sciatic nerves.②BTZ caused lysosomal dysfunction,resulting in the blockade of autophagy flux in Schwann cells and sciatic nerves.③The lysosomal activator Torin1 reversed lysosomal dysfunction caused by BTZ in Schwann cells.④Torin1 improved BTZ-induced mechano-allodynia and demyelination of sciatic nerves.CONCLUSION BTZ led to lyso⁃somal dysfunction in Schwann cells and contrib⁃uted to BIPN.Lysosomal activation could be a promising strategy for BIPN intervention.
文摘OBJECTIVE Progressive isch⁃emic stroke is characterized by aggravation of neurological dysfunction and poor prognosis.Neuroinflammation is involved in the pathological process of cerebral ischemia.Inflammasomes-activated caspase-1 has thus been considered a promising target for stroke therapy.However,it remains not fully understood how caspase-1 ag⁃gravates progressive functional impairment.We previously identified a novel caspase-1 inhibitor CZL-80,the present study is to explore whether CZL-80 protects against progressive ischemic stroke.METHODS Male C57/BL6 mice and cas⁃pase-1-/-mice were subjected to photothrombotic(PT)-induced cerebral ischemia.CZL-80 was in⁃traperitoneally injected daily during 1-7 d,1-4 d,4-7 d after PT.The grid-walking task and the cyl⁃inder task were used to determine the motor function.RESULTS Mice developed primary and the secondary neurological dysfunction at 1 d and 4-7 d after PT onset.The activation of cas⁃pase-1 peaked at 7 d after ischemic stroke and caspase-1 was mainly derived from activated microglia.Treatment with CZL-80(30 mg·kg-1)during 1-7 d significantly improved motor func⁃tion.Administration of CZL-80 during 1-4 d could not ameliorate motor function loss while administration during 4-7 d after PT onset signifi⁃cantly reduced foot faults and forelimb symme⁃try.Remarkably,treatment with CZL-80 during 4-7 d showed no significant difference in efficacy compared with the its administration during 1-7 d,which indicated a key therapeutic window.More⁃over,the neuroprotective effect of CZL-80 during 4-7 d was available at least until 43 d after isch⁃emic stroke,indicating CZL-80 can improve the long-term neurological function after cerebral ischemia.Furthermore,administration of CZL-80(30 mg·kg-1)during 4-7 d after PT onset in cas⁃pase-1-/-mice failed to improve the motor func⁃tion,which suggested that the neuroprotective effect of CZL-80 was caspase-1-dependent.The results showed that CZL-80 did not inhibit the expression of GSDMD and failed to reduce neu⁃ronal loss after ischemia.These results indicated the effect of CZL-80 was not attributable to inhib⁃it pyroptosis.We further found that CZL-80 signif⁃icantly reduced the number of activated microglia in the peri-infarct brain cortex after ischemic stroke,which might be involved in its neuropro⁃tective effect.CONCLUSION CZL-80,a novel caspase-1 inhibitor,improved motor function after progressive ischemic stroke in mice.The effective therapeutic window of CZL-80 would be 4-7 d after ischemia,when the secondary neuro⁃logical dysfunction occurred.Therefore,the inter⁃vention by targeting caspase-1 in this window phase provides a novel strategy for the function⁃al recovery of stroke survivors.
文摘OBJECTIVE Dysfunction of the dopaminergic(DA)neurons is implicated in the pathogenesis of bipolar disorder(BPD).Hista⁃mine receptor 2(Hrh2)is highly expressed in DA neurons,and its antagonists have been reported to induce mania phase of BPD.However,whether Hrh2 on DA neurons contributes to BPD patho⁃genesis is unclear.The present study aims to explore the role of hrh2 on DA neurons in the pathology of BPD.METHODS AAV-FLEX-shHrh2 was injected into a targeted brain area of DAT-Cre mice,leading to a selective brain-regional loss of Hrh2 on DA neurons.A series of behavior tests were used to measure the sponta⁃neous activity,anxiety and depression level of Hrh2-deficient mice.RESULTS①In the open field test and home-cage activity test,Hrh2-defi⁃cient mice displayed increased spontaneous activity.②Hrh2-deficient mice showed reduced depression level in the tail suspension test,forced swimming test and sucrose preference test.③The anxiety level of Hrh2-deficient mice was decreased in the open field test.CONCLU⁃SION Hrh2 on DA neurons is closely related with mania-like behavior.
文摘OBJECTIVE Chronic cerebral hy⁃poperfusion can lead to progressive demyelin⁃ation and ischemic vascular dementia,yet there are no effective treatments.METHODS Magnetic resonance imaging was employed in patients with white matter damage,and optogenetics and skin stroking were exerted to activate glutamater⁃gic neurons in the somatosensory cortex in a clas⁃sical mouse model of ischemia vascular dementia.RESULTS White matter damage was correlated with disrupted cortical structure from MRI results.In a mouse model,activating glutamatergic neu⁃rons in the somatosensory cortex promotes prolif⁃eration of OPCs and remyelination to rescue cog⁃nitive impairment after chronic cerebral hypoper⁃fusion.Such therapeutic action was limited to stimulation with moderate intensity at the upper layers of the cortex,but was achieved over a wide time window after ischemia.Mechanistically,enhanced glutamatergic neuron-OPC functional synaptic connections are required for protection from activation of cortical glutamatergic neurons.Finally,skin stroking activation of the somatosen⁃sory cortex,an easier approach for clinical trans⁃lation,promoted OPC proliferation and remyelin⁃ation as well as cognitive recovery after cerebral hypoperfusion.CONCLUSION Activation of gluta⁃matergic neurons in the somatosensory cortex may serve as novel approaches for treating isch⁃emic vascular dementia through precise modula⁃tion of glutamatergic neuron-OPC circuits.
