Previous studies have shown that sirtuin 1(SIRT1) reduces the production of neuronal amyloid beta(Aβ) and inhibits the inflammatory response of glial cells, thereby generating a neuroprotective effect against Aβ...Previous studies have shown that sirtuin 1(SIRT1) reduces the production of neuronal amyloid beta(Aβ) and inhibits the inflammatory response of glial cells, thereby generating a neuroprotective effect against Aβ neurotoxicity in animal models of Alzheimer's disease. However, the protective effect of SIRT1 on astrocytes is still under investigation. This study established a time point model for the clearance of Aβ in primary astrocytes. Results showed that 12 hours of culture was sufficient for endocytosis of oligomeric Aβ, and 36 hours sufficient for effective degradation. Immunofluorescence demonstrated that Aβ degradation in primary astrocytes relies on lysosome function. Enzymatic agonists or SIRT1 inhibitors were used to stimulate cells over a concentration gradient. Aβ was co-cultured for 36 hours in medium. Western blot assay results under different conditions revealed that SIRT1 relies on its deacetylase activity to promote intracellular Aβ degradation. The experiment further screened SIRT1 using quantitative proteomics to investigate downstream, differentially expressed proteins in the Aβ degradation pathway and selected the ones related to enzyme activity of SIRT1. Most of the differentially expressed proteins detected are close to the primary astrocyte lysosomal pathway. Immunofluorescence staining demonstrated that SIRT1 relies on its deacetylase activity to upregulate lysosome number in primary astrocytes. Taken together, these findings confirm that SIRT1 relies on its deacetylase activity to upregulate lysosome number, thereby facilitating oligomeric Aβ degradation in primary astrocytes.展开更多
Alzheimer’s disease(AD)is the most common progressive neurodegenerative disorder.It is often lethal and currently lacks a satisfactory therapy.The disease has a specific neuro-pathological profile:accumulation of pro...Alzheimer’s disease(AD)is the most common progressive neurodegenerative disorder.It is often lethal and currently lacks a satisfactory therapy.The disease has a specific neuro-pathological profile:accumulation of proteinaceous deposits in the brain–amyloid plaques(containingβ-amyloid peptides)and neurofibrillary tangles which are accumulation of a profusion of long stringy tangles of proteins called tau.Between the two highly recognized AD hypotheses,amyloid beta(Aβ)peptide aggregation and accumulation play a significant role and are considered as an important mechanism of AD pathology.Aβis a proteolytic product of amyloid precursor protein and genetic studies supported the relevance of Aβin AD pathogenesis.A large number of small molecules were studied for their ability to inhibit Aβ-aggregation in oligomer form or after fibrillization.However,the protein-misfolding process has certain setbacks which are inevitable due to the different morphology of protein.In recent years,it has been demonstrated that tau also plays a central role in pathogenesis of this disease.Moreover,abnormal post-translational modifications of tau,in particular,increases in acetylation at specific sites likely contribute to the toxicity of tau.Although it is evident that tau with these aberrant post-translational modifications likely facilitates neurodegeneration,the precise cellular mechanisms by which tau compromises neuronal function remain unknown.In addition,much remains to be learned about new interventions that might be developed to prevent or reduce the negative impact of tau posttranslational modifications-related damage.This review article addresses the key roles of amyloid beta and tau protein in AD as well as the possible therapeutic agents that can reduce the toxic levels of both the proteins,and thus providing beneficial effect for the AD patients.展开更多
Amyloid-beta peptide is the main component of amyloid plaques, which are found in Alzhei- mer's disease. The generation and deposition of amyloid-beta is one of the crucial factors for the onset and progression of Al...Amyloid-beta peptide is the main component of amyloid plaques, which are found in Alzhei- mer's disease. The generation and deposition of amyloid-beta is one of the crucial factors for the onset and progression of Alzheimer's disease. Lipid rafts are glycolipid-rich liquid domains of the plasma membrane, where certain types of protein tend to aggregate and intercalate. Lipid rafts are involved in the generation of amyloid-beta oligomers and the formation of amyloid-beta peptides. In this paper, we review the mechanism by which lipid rafts disturb the aberrant deg- radative autophagic-lysosomal pathway of amyloid-beta, which plays an important role in the pathological process of Alzheimer's disease. Moreover, we describe this mechanism from the view of the Two-system Theory of fasciology and thus, suggest that lipid rafts may be a new target of Alzheimer's disease treatment.展开更多
The accumulation of amyloid β peptide<sub>1-42</sub> (Aβ<sub>1-42</sub>) masses in the brains of Alzheimer’s Disease (AD) patients is associated with neuronal loss and memory deficits. We ha...The accumulation of amyloid β peptide<sub>1-42</sub> (Aβ<sub>1-42</sub>) masses in the brains of Alzheimer’s Disease (AD) patients is associated with neuronal loss and memory deficits. We have previously reported that oral administration of docosahexaenoic acid (DHA, C22:6, n-3) significantly decreases Aβ burden in the brains of AD model rats and that direct in vitro incubation of DHA with Aβ<sub>1-42</sub> curbs the progression of amyloid fibrillation. In the present in silico study, we investigated whether DHA computationally binds with amyloid peptides. The NMR solution structures of Aβ<sub>1-42</sub> were downloaded from the Protein Data Bank (PDB IDs: 1Z0Q and 2BEG). The binding of DHA to Aβ peptides was assessed by molecular docking using both a flexible and rigid docking system. Thioflavin T (ThT) was used as positive control. The chemical structures of ThT and DHA were modeled and converted to the PDB format using PRODRUG. Drug-like properties of DHA were evaluated by ADME (Absorption, Distribution, Metabolism, and Excretion). DHA was found to successfully dock with Aβ<sub>1-42</sub>. Computational analyses of the binding of DHA to Aβ<sub>1-42</sub>, as evaluated by docking studies, further corroborated the inhibitory effect of DHA on in vitro Aβ<sub>1-42</sub> fibrillogenesis and might explain the in vivo reduction of amyloid burden observed in the brains of DHA-administered AD model rats demonstrated in our previous study. These computational data suggest the potential utility of DHA as a preventive medication in Aβ-induced neurodegenerative diseases, including AD.展开更多
Background:The aggregation of amyloidβ(Aβ)is central in the pathogenesis of Alzheimer’s disease(AD).Recently it has been shown that specifically,larger,Thioflavin T-binding Aβaggregates are associated with increas...Background:The aggregation of amyloidβ(Aβ)is central in the pathogenesis of Alzheimer’s disease(AD).Recently it has been shown that specifically,larger,Thioflavin T-binding Aβaggregates are associated with increased neuroinflammation and cytokine release.This study was aimed to quantify fibrillary amyloid aggregates,so-called nanoplaques,and investigate their relationship with cytokines in the cerebrospinal fluid(CSF).Methods:CSF was collected from 111 patients assessed for cognitive complaints at the Oslo University Hospital Memory Clinic.The patients were grouped based on their amyloid status.The CSF nanoplaque concentration was quantified with the Thioflavin T-fluorescence correlation spectroscopy(ThT-FCS)assay.The levels of nine cytokines(eotaxin-1,granulocyte stimulating factor,interleukin[IL]-6,IL-7,IL-8,monocyte chemoattractant protein-1,gammainduced protein 10,macrophage inflammatory protein[MIP]-1α,and MIP-1β)were quantified with a magnetic bead-based multiplex assay and read on a Luminex IS 200 instrument.Results:There were 49 amyloid-negative and 62 amyloid-positive patients in the cohort;none of the cytokines differed significantly between the amyloid groups.The increased nanoplaque levels were associated with levels of MIP-1βbelow the lower limit of quantification,and with decreased levels of MIP-1αand IL-8.The associations remained significant when adjusted for age,sex,cognitive function,apolipoproteinε4 status and CSF core biomarker levels.Conclusion:The cytokine levels were not associated with amyloid status in this cohort.The nanoplaque levels were negatively associated with MIP-1β,MIP-1αand IL-8,which is in line with recent findings suggesting that the upregulation of some cytokine markers has a protective role and is negatively associated with AD progression.展开更多
Alzheimer’s disease(AD)is a complex,heterogeneous,progressive disease and is the most common type of neurodegenerative dementia.The prevalence of AD is expected to increase as the population ages,placing an additiona...Alzheimer’s disease(AD)is a complex,heterogeneous,progressive disease and is the most common type of neurodegenerative dementia.The prevalence of AD is expected to increase as the population ages,placing an additional burden on national healthcare systems.There is a large need for new diagnostic tests that can detect AD at an early stage with high specificity at relatively low cost.The development of modern analytical diagnostic tools has made it possible to determine several biomarkers of AD with high specificity,including pathogenic proteins,markers of synaptic dysfunction,and markers of inflammation in the blood.There is a considerable potential in using microRNA(miRNA)as markers of AD,and diagnostic studies based on miRNA panels suggest that AD could potentially be determined with high accuracy for individual patients.Studies of the retina with improved methods of visualization of the fundus are also showing promising results for the potential diagnosis of the disease.This review focuses on the recent developments of blood,plasma,and ocular biomarkers for the diagnosis of AD.展开更多
Alzheimer’s disease(AD),the most common neurodegenerative disorder,is characterized by memory loss and cognitive dysfunction.The accumulation of misfolded protein aggregates including amyloid beta(Aβ)peptides and mi...Alzheimer’s disease(AD),the most common neurodegenerative disorder,is characterized by memory loss and cognitive dysfunction.The accumulation of misfolded protein aggregates including amyloid beta(Aβ)peptides and microtubule associated protein tau(MAPT/tau)in neuronal cells are hallmarks of AD.So far,the exact underlying mechanisms for the aetiologies of AD have not been fully understood and the effective treatment for AD is limited.Autophagy is an evolutionarily conserved cellular catabolic process by which damaged cellular organelles and protein aggregates are degraded via lysosomes.Recently,there is accumulating evidence linking the impairment of the autophagy-lysosomal pathway with AD pathogenesis.Interestingly,the enhancement of autophagy to remove protein aggregates has been proposed as a promising therapeutic strategy for AD.Here,we first summarize the recent genetic,pathological and experimental studies regarding the impairment of the autophagy-lysosomal pathway in AD.We then describe the interplay between the autophagy-lysosomal pathway and two pathological proteins,Aβand MAPT/tau,in AD.Finally,we discuss potential therapeutic strategies and small molecules that target the autophagy-lysosomal pathway for AD treatment both in animal models and in clinical trials.Overall,this article highlights the pivotal functions of the autophagy-lysosomal pathway in AD pathogenesis and potential druggable targets in the autophagy-lysosomal pathway for AD treatment.展开更多
基金supported by the National Natural Science Foundation of China,No.31670832,31470807,31270872a grant from the National Key Research and Development Program of China,No.2016YFA0500301a grant from the State Key Laboratory of Protein and Plant Gene Research,College of Life Sciences,Peking University,China
文摘Previous studies have shown that sirtuin 1(SIRT1) reduces the production of neuronal amyloid beta(Aβ) and inhibits the inflammatory response of glial cells, thereby generating a neuroprotective effect against Aβ neurotoxicity in animal models of Alzheimer's disease. However, the protective effect of SIRT1 on astrocytes is still under investigation. This study established a time point model for the clearance of Aβ in primary astrocytes. Results showed that 12 hours of culture was sufficient for endocytosis of oligomeric Aβ, and 36 hours sufficient for effective degradation. Immunofluorescence demonstrated that Aβ degradation in primary astrocytes relies on lysosome function. Enzymatic agonists or SIRT1 inhibitors were used to stimulate cells over a concentration gradient. Aβ was co-cultured for 36 hours in medium. Western blot assay results under different conditions revealed that SIRT1 relies on its deacetylase activity to promote intracellular Aβ degradation. The experiment further screened SIRT1 using quantitative proteomics to investigate downstream, differentially expressed proteins in the Aβ degradation pathway and selected the ones related to enzyme activity of SIRT1. Most of the differentially expressed proteins detected are close to the primary astrocyte lysosomal pathway. Immunofluorescence staining demonstrated that SIRT1 relies on its deacetylase activity to upregulate lysosome number in primary astrocytes. Taken together, these findings confirm that SIRT1 relies on its deacetylase activity to upregulate lysosome number, thereby facilitating oligomeric Aβ degradation in primary astrocytes.
基金Guha S wishes to thank UR PDA Career Enhancement Award 2020 for covering the subscription fee of bio-render and other bureaucratic cost.Subramaniyam R wishes to thank DST-inspire program for the research grant(No.DST/INSPIRE/04/2015/001945).
文摘Alzheimer’s disease(AD)is the most common progressive neurodegenerative disorder.It is often lethal and currently lacks a satisfactory therapy.The disease has a specific neuro-pathological profile:accumulation of proteinaceous deposits in the brain–amyloid plaques(containingβ-amyloid peptides)and neurofibrillary tangles which are accumulation of a profusion of long stringy tangles of proteins called tau.Between the two highly recognized AD hypotheses,amyloid beta(Aβ)peptide aggregation and accumulation play a significant role and are considered as an important mechanism of AD pathology.Aβis a proteolytic product of amyloid precursor protein and genetic studies supported the relevance of Aβin AD pathogenesis.A large number of small molecules were studied for their ability to inhibit Aβ-aggregation in oligomer form or after fibrillization.However,the protein-misfolding process has certain setbacks which are inevitable due to the different morphology of protein.In recent years,it has been demonstrated that tau also plays a central role in pathogenesis of this disease.Moreover,abnormal post-translational modifications of tau,in particular,increases in acetylation at specific sites likely contribute to the toxicity of tau.Although it is evident that tau with these aberrant post-translational modifications likely facilitates neurodegeneration,the precise cellular mechanisms by which tau compromises neuronal function remain unknown.In addition,much remains to be learned about new interventions that might be developed to prevent or reduce the negative impact of tau posttranslational modifications-related damage.This review article addresses the key roles of amyloid beta and tau protein in AD as well as the possible therapeutic agents that can reduce the toxic levels of both the proteins,and thus providing beneficial effect for the AD patients.
基金supported by a grant from Projects of High-tech Industrialization of Guangdong Province of China,No.2011B010500004a grant from National Financial Major Project of China
文摘Amyloid-beta peptide is the main component of amyloid plaques, which are found in Alzhei- mer's disease. The generation and deposition of amyloid-beta is one of the crucial factors for the onset and progression of Alzheimer's disease. Lipid rafts are glycolipid-rich liquid domains of the plasma membrane, where certain types of protein tend to aggregate and intercalate. Lipid rafts are involved in the generation of amyloid-beta oligomers and the formation of amyloid-beta peptides. In this paper, we review the mechanism by which lipid rafts disturb the aberrant deg- radative autophagic-lysosomal pathway of amyloid-beta, which plays an important role in the pathological process of Alzheimer's disease. Moreover, we describe this mechanism from the view of the Two-system Theory of fasciology and thus, suggest that lipid rafts may be a new target of Alzheimer's disease treatment.
文摘The accumulation of amyloid β peptide<sub>1-42</sub> (Aβ<sub>1-42</sub>) masses in the brains of Alzheimer’s Disease (AD) patients is associated with neuronal loss and memory deficits. We have previously reported that oral administration of docosahexaenoic acid (DHA, C22:6, n-3) significantly decreases Aβ burden in the brains of AD model rats and that direct in vitro incubation of DHA with Aβ<sub>1-42</sub> curbs the progression of amyloid fibrillation. In the present in silico study, we investigated whether DHA computationally binds with amyloid peptides. The NMR solution structures of Aβ<sub>1-42</sub> were downloaded from the Protein Data Bank (PDB IDs: 1Z0Q and 2BEG). The binding of DHA to Aβ peptides was assessed by molecular docking using both a flexible and rigid docking system. Thioflavin T (ThT) was used as positive control. The chemical structures of ThT and DHA were modeled and converted to the PDB format using PRODRUG. Drug-like properties of DHA were evaluated by ADME (Absorption, Distribution, Metabolism, and Excretion). DHA was found to successfully dock with Aβ<sub>1-42</sub>. Computational analyses of the binding of DHA to Aβ<sub>1-42</sub>, as evaluated by docking studies, further corroborated the inhibitory effect of DHA on in vitro Aβ<sub>1-42</sub> fibrillogenesis and might explain the in vivo reduction of amyloid burden observed in the brains of DHA-administered AD model rats demonstrated in our previous study. These computational data suggest the potential utility of DHA as a preventive medication in Aβ-induced neurodegenerative diseases, including AD.
基金This work was supported by funding from the Olav Thon Foundation,The Norwegian Health Association,Swedish Foundation for Strategic Research(SBE13-0115)Swedish Research Council(VR 2018-05337)+3 种基金Olle Engkvists Foundation(199-0480)Magnus Bergvalls Foundation(2018-02642)Region Stockholm(ALF projects 20180365 and 20190561)The funding agencies had no influence on the study design,data collection,data analysis,interpretation of the data or the manuscript writing.
文摘Background:The aggregation of amyloidβ(Aβ)is central in the pathogenesis of Alzheimer’s disease(AD).Recently it has been shown that specifically,larger,Thioflavin T-binding Aβaggregates are associated with increased neuroinflammation and cytokine release.This study was aimed to quantify fibrillary amyloid aggregates,so-called nanoplaques,and investigate their relationship with cytokines in the cerebrospinal fluid(CSF).Methods:CSF was collected from 111 patients assessed for cognitive complaints at the Oslo University Hospital Memory Clinic.The patients were grouped based on their amyloid status.The CSF nanoplaque concentration was quantified with the Thioflavin T-fluorescence correlation spectroscopy(ThT-FCS)assay.The levels of nine cytokines(eotaxin-1,granulocyte stimulating factor,interleukin[IL]-6,IL-7,IL-8,monocyte chemoattractant protein-1,gammainduced protein 10,macrophage inflammatory protein[MIP]-1α,and MIP-1β)were quantified with a magnetic bead-based multiplex assay and read on a Luminex IS 200 instrument.Results:There were 49 amyloid-negative and 62 amyloid-positive patients in the cohort;none of the cytokines differed significantly between the amyloid groups.The increased nanoplaque levels were associated with levels of MIP-1βbelow the lower limit of quantification,and with decreased levels of MIP-1αand IL-8.The associations remained significant when adjusted for age,sex,cognitive function,apolipoproteinε4 status and CSF core biomarker levels.Conclusion:The cytokine levels were not associated with amyloid status in this cohort.The nanoplaque levels were negatively associated with MIP-1β,MIP-1αand IL-8,which is in line with recent findings suggesting that the upregulation of some cytokine markers has a protective role and is negatively associated with AD progression.
基金Uppsala University.HBS is supported by the Swedish Research Council and the Swedish Brain Foundation。
文摘Alzheimer’s disease(AD)is a complex,heterogeneous,progressive disease and is the most common type of neurodegenerative dementia.The prevalence of AD is expected to increase as the population ages,placing an additional burden on national healthcare systems.There is a large need for new diagnostic tests that can detect AD at an early stage with high specificity at relatively low cost.The development of modern analytical diagnostic tools has made it possible to determine several biomarkers of AD with high specificity,including pathogenic proteins,markers of synaptic dysfunction,and markers of inflammation in the blood.There is a considerable potential in using microRNA(miRNA)as markers of AD,and diagnostic studies based on miRNA panels suggest that AD could potentially be determined with high accuracy for individual patients.Studies of the retina with improved methods of visualization of the fundus are also showing promising results for the potential diagnosis of the disease.This review focuses on the recent developments of blood,plasma,and ocular biomarkers for the diagnosis of AD.
基金funding supports from the National Natural Science Foundation of China(82003721,82071193,32170774 and 32000673)Shenzhen Science and Technology Innovation Commission(JCYJ20210324114014039,China)+1 种基金China Postdoctoral Science Foundation(2020M683182)Guangdong Basic and Applied Basic Research Foundation(2020A1515110549,China)。
文摘Alzheimer’s disease(AD),the most common neurodegenerative disorder,is characterized by memory loss and cognitive dysfunction.The accumulation of misfolded protein aggregates including amyloid beta(Aβ)peptides and microtubule associated protein tau(MAPT/tau)in neuronal cells are hallmarks of AD.So far,the exact underlying mechanisms for the aetiologies of AD have not been fully understood and the effective treatment for AD is limited.Autophagy is an evolutionarily conserved cellular catabolic process by which damaged cellular organelles and protein aggregates are degraded via lysosomes.Recently,there is accumulating evidence linking the impairment of the autophagy-lysosomal pathway with AD pathogenesis.Interestingly,the enhancement of autophagy to remove protein aggregates has been proposed as a promising therapeutic strategy for AD.Here,we first summarize the recent genetic,pathological and experimental studies regarding the impairment of the autophagy-lysosomal pathway in AD.We then describe the interplay between the autophagy-lysosomal pathway and two pathological proteins,Aβand MAPT/tau,in AD.Finally,we discuss potential therapeutic strategies and small molecules that target the autophagy-lysosomal pathway for AD treatment both in animal models and in clinical trials.Overall,this article highlights the pivotal functions of the autophagy-lysosomal pathway in AD pathogenesis and potential druggable targets in the autophagy-lysosomal pathway for AD treatment.