Ischemic stroke often induces excessive neuronal autophagy, resulting in brain damage; meanwhile, inflammatory responses stimulated by ischemia exacerbate neural injury. However, interactions between neuronal autophag...Ischemic stroke often induces excessive neuronal autophagy, resulting in brain damage; meanwhile, inflammatory responses stimulated by ischemia exacerbate neural injury. However, interactions between neuronal autophagy and microglial inflammation following ischemic stroke are poorly understood. CX3CL1/fractalkine, a membrane-bound chemokine expressed on neurons, can suppress microglial inflammation by binding to its receptor CX3CR1 on microglia. In the present study, to investigate whether autophagy could alter CX3CL1 expression on neurons and consequently change microglial inflammatory activity, middle cerebral artery occlusion(MCAO) was established in Sprague-Dawley rats to model ischemic stroke, and tissues from the ischemic penumbra were obtained to evaluate autophagy level and microglial inflammatory activity. MCAO rats were administered 3-methyladenine(autophagy inhibitor) or Tat-Beclin 1(autophagy inducer). Western blot assays were conducted to quantify expression of Beclin-1, nuclear factor kappa Bp65(NF-κB), light chain 3B(LC3B), and CX3CL1 in ischemic penumbra. Moreover, immunofluorescence staining was performed to quantify numbers of LC3B-, CX3CL1-, and Iba-1-positive cells in ischemic penumbra. In addition, enzyme linked immunosorbent assays were utilized to analyze concentrations of tumor necrosis factor alpha(TNF-α), interleukin 6(IL-6), interleukin 1 beta(IL-1β), and prostaglandin E2(PGE2). A dry/wet weight method was used to detect brain water content, while 2,3,5,-triphenyltetrazolium chloride staining was utilized to measure infarct volume. The results demonstrated that autophagy signaling(Beclin-1 and LC3B expression) in penumbra was prominently activated by MCAO, while CX3CL1 expression on autophagic neurons was significantly reduced and microglial inflammation was markedly activated. However, after inhibition of autophagy signaling with 3-methyladenine, CX3CL1 expression on neurons was obviously increased, whereas Iba-1 and NF-κB expression was downregulated; TNF-α, IL-6, IL-1β, and PGE展开更多
SIRT6 is a NAD＊-dependent histone deacetylase and has been implicated in the regulation of genomic stability, DNA repair, metabolic homeostasis and several diseases. The effect of SIRT6 in cerebral ischemia and oxyge...SIRT6 is a NAD＊-dependent histone deacetylase and has been implicated in the regulation of genomic stability, DNA repair, metabolic homeostasis and several diseases. The effect of SIRT6 in cerebral ischemia and oxygen/glucose deprivation （OGD） has been reported, however the role of SIRT6 in oxidative stress damage remains unclear. Here we used SH-SY5Y neuronal cells and found that overexpression of SIRT6 led to decreased cell viability and increased necrotic cell death and reactive oxygen species （ROS） production under oxidative stress. Mechanistic study revealed that SlRT6 induced autophagy via attenuation of AKT signaling and treatment with autophagy inhibitor 3-MA or knockdown of autophagy-related protein Atg5 rescued HzO2-induced neuronal injury. Conversely, SIRT6 inhibition suppressed autophagy and reduced oxidative stressinduced neuronal damage. These results suggest that SIRT6 might be a potential therapeutic target for neuroprotection.展开更多
Alzheimer's disease(AD)is a prevalent and deleterious neurodegenerative disorder characterized by an irreversible and progressive impairment of cognitive abilities as well as the formation of amyloidβ(Aβ)plaques...Alzheimer's disease(AD)is a prevalent and deleterious neurodegenerative disorder characterized by an irreversible and progressive impairment of cognitive abilities as well as the formation of amyloidβ(Aβ)plaques and neurofibrillary tangles(NFTs)in the brain.By far,the precise mechanisms of AD are not fully understood and no interventions are available to effectively slow down progression of the disease.Autophagy is a conserved degradation pathway that is crucial to maintain cellular homeostasis by targeting damaged organelles,pathogens,and disease-prone protein aggregates to lysosome for degradation.Emerging evidence suggests dysfunctional autophagy clearance pathway as a potential cellular mechanism underlying the pathogenesis of AD in affected neurons.Here we summarize the current evidence for autophagy dysfunction in the pathophysiology of AD and discuss the role of autophagy in the regulation of AD-related protein degradation and neuroinflammation in neurons and glial cells.Finally,we review the autophagy modulators reported in the treatment of AD models and discuss the obstacles and opportunities for potential clinical application of the novel autophagy activators for AD therapy.展开更多
The balance of autophagy, apoptosis and necroptosis is crucial to determine the outcome of the cellular response to cholesterol dysregulation. Cholesterol plays a major role in regulating the properties of cell membra...The balance of autophagy, apoptosis and necroptosis is crucial to determine the outcome of the cellular response to cholesterol dysregulation. Cholesterol plays a major role in regulating the properties of cell membranes, especially as regards their fluidity, and the regulation of its biosynthesis influences the shape and functions of these membranes. Whilst dietary cholesterol can easily be distributed to most organs, the central nervous system, whose membranes are particularly rich in cholesterol, mainly relies on de novo synthesis. For this reason, defects in the biosynthesis of cholesterol can variably affect the development of central nervous system. Moreover, defective synthesis of cholesterol and its intermediates may reflect both on structural cell anomalies and on the response to inflammatory stimuli. Examples of such disorders include mevalonate kinase deficiency, and Smith-Lemli-Opitz syndrome, due to deficiency in biosynthetic enzymes, and type C Niemann-Pick syndrome, due to altered cholesterol trafficking across cell compartments. Autophagy, as a crucial pathway dedicated to the degradation of cytosolic proteins and organelles, plays an essential role in the maintenance of homeostasis and in the turnover of the cytoplasmic material especially in the presence of imbalances such as those resulting from alteration of cholesterol metabolism. Manipulating the process of autophagy can offer possible strategies for improving neuronal cell viability and function in these genetic disorders.展开更多
After hypoxia, ischemia, or inflammatory injuries to the central nervous system, the damaged cells release a large amount of adenosine triphosphate, which may cause secondary neuronal death. Autophagy is a form of cel...After hypoxia, ischemia, or inflammatory injuries to the central nervous system, the damaged cells release a large amount of adenosine triphosphate, which may cause secondary neuronal death. Autophagy is a form of cell death that also has neuroprotective effects. Cell Counting Kit assay, monodansylcadaverine staining, flow cytometry, western blotting, and real-time PCR were used to determine the effects of exogenous adenosine triphosphate treatment at different concentrations （2, 4, 6, 8, 10 mmol/L） over time （1, 2, 3, and 6 hours） on the apoptosis and autophagy of SH-SY5Y cells. High concentrations of extracellular adenosine triphosphate induced autophagy and apoptosis of SH-SYSY cells. The enhanced autophagy first appeared, and peaked at 1 hour after treatment with adenosine triphosphate. Cell apoptosis peaked at 3 hours, and persisted through 6 hours. With prolonged exposure to the adenosine triphosphate treatment, the fraction of apoptotic cells increased. These data suggest that the SH-SY5Y neural cells initiated autophagy against apoptosis within an hour of adenosine triphosphate treatment to protect themselves against injury.展开更多
盐诱导激酶(salt-inducible kinase,SIK)是属于单磷酸腺苷激活蛋白激酶/蔗糖非酵解1(adenosine monophosphate-activated protein kinase and sucrose non-fermenting 1,AMPK/SNF1)家族的丝氨酸/苏氨酸蛋白激酶。SIK自1998年被发现以来...盐诱导激酶(salt-inducible kinase,SIK)是属于单磷酸腺苷激活蛋白激酶/蔗糖非酵解1(adenosine monophosphate-activated protein kinase and sucrose non-fermenting 1,AMPK/SNF1)家族的丝氨酸/苏氨酸蛋白激酶。SIK自1998年被发现以来,越来越多的功能被人们证实和认可。现已发现,SIK在能量代谢、细胞信号转导、细胞周期、肿瘤、黑素原生成等诸多方面有重要作用。通过查阅近些年相关文献,在此重点总结一下SIK2功能的研究进展。展开更多
基金supported by the National Natural Science Foundation of China,No.81660383(to YHD),81860411(to HYH)a grant from the Applied Basic Research Projects of Yunnan Province of China,No.2017FB113(to YHD)the Scientific Research Fund of Yunnan Provincial Department of Education of China,No.2018JS016(to HYH)
文摘Ischemic stroke often induces excessive neuronal autophagy, resulting in brain damage; meanwhile, inflammatory responses stimulated by ischemia exacerbate neural injury. However, interactions between neuronal autophagy and microglial inflammation following ischemic stroke are poorly understood. CX3CL1/fractalkine, a membrane-bound chemokine expressed on neurons, can suppress microglial inflammation by binding to its receptor CX3CR1 on microglia. In the present study, to investigate whether autophagy could alter CX3CL1 expression on neurons and consequently change microglial inflammatory activity, middle cerebral artery occlusion(MCAO) was established in Sprague-Dawley rats to model ischemic stroke, and tissues from the ischemic penumbra were obtained to evaluate autophagy level and microglial inflammatory activity. MCAO rats were administered 3-methyladenine(autophagy inhibitor) or Tat-Beclin 1(autophagy inducer). Western blot assays were conducted to quantify expression of Beclin-1, nuclear factor kappa Bp65(NF-κB), light chain 3B(LC3B), and CX3CL1 in ischemic penumbra. Moreover, immunofluorescence staining was performed to quantify numbers of LC3B-, CX3CL1-, and Iba-1-positive cells in ischemic penumbra. In addition, enzyme linked immunosorbent assays were utilized to analyze concentrations of tumor necrosis factor alpha(TNF-α), interleukin 6(IL-6), interleukin 1 beta(IL-1β), and prostaglandin E2(PGE2). A dry/wet weight method was used to detect brain water content, while 2,3,5,-triphenyltetrazolium chloride staining was utilized to measure infarct volume. The results demonstrated that autophagy signaling(Beclin-1 and LC3B expression) in penumbra was prominently activated by MCAO, while CX3CL1 expression on autophagic neurons was significantly reduced and microglial inflammation was markedly activated. However, after inhibition of autophagy signaling with 3-methyladenine, CX3CL1 expression on neurons was obviously increased, whereas Iba-1 and NF-κB expression was downregulated; TNF-α, IL-6, IL-1β, and PGE
文摘SIRT6 is a NAD＊-dependent histone deacetylase and has been implicated in the regulation of genomic stability, DNA repair, metabolic homeostasis and several diseases. The effect of SIRT6 in cerebral ischemia and oxygen/glucose deprivation （OGD） has been reported, however the role of SIRT6 in oxidative stress damage remains unclear. Here we used SH-SY5Y neuronal cells and found that overexpression of SIRT6 led to decreased cell viability and increased necrotic cell death and reactive oxygen species （ROS） production under oxidative stress. Mechanistic study revealed that SlRT6 induced autophagy via attenuation of AKT signaling and treatment with autophagy inhibitor 3-MA or knockdown of autophagy-related protein Atg5 rescued HzO2-induced neuronal injury. Conversely, SIRT6 inhibition suppressed autophagy and reduced oxidative stressinduced neuronal damage. These results suggest that SIRT6 might be a potential therapeutic target for neuroprotection.
基金This study was supported by China minister of Science and Technology grant MoST-2017YFE0120100the Science and Technology Development Fund,Macao SAR(No.0110/2018/A3,0128/2019/A3,China)+1 种基金the University of Macao grants(No.MYRG2019-00129-ICMS,China)awarded to Jia-Hong LuNIH/R01NS060123 and R01 R01AG072520(USA)awarded to Zhenyu Yue.
文摘Alzheimer's disease(AD)is a prevalent and deleterious neurodegenerative disorder characterized by an irreversible and progressive impairment of cognitive abilities as well as the formation of amyloidβ(Aβ)plaques and neurofibrillary tangles(NFTs)in the brain.By far,the precise mechanisms of AD are not fully understood and no interventions are available to effectively slow down progression of the disease.Autophagy is a conserved degradation pathway that is crucial to maintain cellular homeostasis by targeting damaged organelles,pathogens,and disease-prone protein aggregates to lysosome for degradation.Emerging evidence suggests dysfunctional autophagy clearance pathway as a potential cellular mechanism underlying the pathogenesis of AD in affected neurons.Here we summarize the current evidence for autophagy dysfunction in the pathophysiology of AD and discuss the role of autophagy in the regulation of AD-related protein degradation and neuroinflammation in neurons and glial cells.Finally,we review the autophagy modulators reported in the treatment of AD models and discuss the obstacles and opportunities for potential clinical application of the novel autophagy activators for AD therapy.
基金supported by a grant from the Institute for Maternal and Child Health–Istituto di Ricovero e Cura a Carattere Scientifico "Burlo Garofolo"–Trieste,Italy(RC 24/2017to AT)
文摘The balance of autophagy, apoptosis and necroptosis is crucial to determine the outcome of the cellular response to cholesterol dysregulation. Cholesterol plays a major role in regulating the properties of cell membranes, especially as regards their fluidity, and the regulation of its biosynthesis influences the shape and functions of these membranes. Whilst dietary cholesterol can easily be distributed to most organs, the central nervous system, whose membranes are particularly rich in cholesterol, mainly relies on de novo synthesis. For this reason, defects in the biosynthesis of cholesterol can variably affect the development of central nervous system. Moreover, defective synthesis of cholesterol and its intermediates may reflect both on structural cell anomalies and on the response to inflammatory stimuli. Examples of such disorders include mevalonate kinase deficiency, and Smith-Lemli-Opitz syndrome, due to deficiency in biosynthetic enzymes, and type C Niemann-Pick syndrome, due to altered cholesterol trafficking across cell compartments. Autophagy, as a crucial pathway dedicated to the degradation of cytosolic proteins and organelles, plays an essential role in the maintenance of homeostasis and in the turnover of the cytoplasmic material especially in the presence of imbalances such as those resulting from alteration of cholesterol metabolism. Manipulating the process of autophagy can offer possible strategies for improving neuronal cell viability and function in these genetic disorders.
基金supported by the National Natural Science Foundation of China,No.81371346,81271376
文摘After hypoxia, ischemia, or inflammatory injuries to the central nervous system, the damaged cells release a large amount of adenosine triphosphate, which may cause secondary neuronal death. Autophagy is a form of cell death that also has neuroprotective effects. Cell Counting Kit assay, monodansylcadaverine staining, flow cytometry, western blotting, and real-time PCR were used to determine the effects of exogenous adenosine triphosphate treatment at different concentrations （2, 4, 6, 8, 10 mmol/L） over time （1, 2, 3, and 6 hours） on the apoptosis and autophagy of SH-SY5Y cells. High concentrations of extracellular adenosine triphosphate induced autophagy and apoptosis of SH-SYSY cells. The enhanced autophagy first appeared, and peaked at 1 hour after treatment with adenosine triphosphate. Cell apoptosis peaked at 3 hours, and persisted through 6 hours. With prolonged exposure to the adenosine triphosphate treatment, the fraction of apoptotic cells increased. These data suggest that the SH-SY5Y neural cells initiated autophagy against apoptosis within an hour of adenosine triphosphate treatment to protect themselves against injury.
文摘盐诱导激酶(salt-inducible kinase,SIK)是属于单磷酸腺苷激活蛋白激酶/蔗糖非酵解1(adenosine monophosphate-activated protein kinase and sucrose non-fermenting 1,AMPK/SNF1)家族的丝氨酸/苏氨酸蛋白激酶。SIK自1998年被发现以来,越来越多的功能被人们证实和认可。现已发现,SIK在能量代谢、细胞信号转导、细胞周期、肿瘤、黑素原生成等诸多方面有重要作用。通过查阅近些年相关文献,在此重点总结一下SIK2功能的研究进展。
