The carboxyl-terminal amino acids 272-299-truncated apoE4 （△272-299） is the main fragments of apoE4 hydrolysate in neurons. The effects of truncated-ApoE4 （△272-299） overexpression on tau phosphorylation in cult...The carboxyl-terminal amino acids 272-299-truncated apoE4 （△272-299） is the main fragments of apoE4 hydrolysate in neurons. The effects of truncated-ApoE4 （△272-299） overexpression on tau phosphorylation in cultured N2a cells were investigated. The truncated-apoE4 （△272-299） cDNA was subcloned into pEGFP-c3 to form recombinant pEGFP-T-apoE4, pEGFP-c3, pEGFP-T- apoE4 and pEGFP-apoE4 were transfected into N2a cells respectively by lipofectamine 2000 method. After 24-48 h, tau phosphorylation was detected by Western blot assay and glycogen synthase kinase-3 （GSK-3） activity by using GSK-3 activity assay. The results showed that the overexpression of both full length-apoE4 and truncated apoE4 fragments in N2a cells induced a dramatic increase in phosphorylation of tau at Ser202 sites and the activation of GSK-3 as compared with untransfected cells, most significantly in the cells transfected with pEGFP-T-apoE4 （P〈0. 05）. It was concluded that in vitro overexpression of truncated-ApoE4 （△272-299） can result in tau hyperphosphorylation in N2a cells by activating GSK-3, suggesting truncated-ApoE4 （△272-299） might contribute the pathogenesis of Alzheimer disease.展开更多
Alzheimer's disease(AD)is a neurodegenerative disease characterized by progressive cognitive dysfunction and behavioral impairment that occurs in old age and pre-old age[1].Apolipoprotein4(ApoE4)is the most import...Alzheimer's disease(AD)is a neurodegenerative disease characterized by progressive cognitive dysfunction and behavioral impairment that occurs in old age and pre-old age[1].Apolipoprotein4(ApoE4)is the most important genetic risk factor for late-onset AD[2].Peripheral apoE4 is separated from that in the CNS by the blood-brain barrier(BBB)and is abundantly produced by the liver and macrophages and released into the blood to modulate lipid-related events.展开更多
To scrutinize the disorders caused by human mutant apoE7/apoE4, human apoE4 and E7 transgenic mice were established with microinjection technique to examine molecular genetic phenomena in vivo. The integration and exp...To scrutinize the disorders caused by human mutant apoE7/apoE4, human apoE4 and E7 transgenic mice were established with microinjection technique to examine molecular genetic phenomena in vivo. The integration and expression of h-apoE mutant genes in transgenic mice were determined with Southern blot, Northern blot and ELISA. The current studies indicated that the transgenes and the phenotypes regarding expression of transgenes could be transmitted stably in transgenic lines. The levels of serum lipid in transgenic mice showed the characteristics of hyperlipidemia. Besides, behavior tests demonstrated the degeneration of learning and memory in transgenic mice. Short life span was observed in 2 transgenic lines. After fed with high lipid food high serum lipid was found both in normal and transgenic mice, but their mechanism regulating lipid metabolism was different. It was also verified that the human apoE mutants located at either N-terminal or C-terminal had the same pathogenesis regarding disorders of lipid metabolism in murine.展开更多
Background:Apolipoprotein E4(ApoE4)allele is the strongest genetic risk factor for late-onset Alzheimer's disease,and it can aggravate depressive symptoms in non-AD patients.However,the impact of ApoE4 on AD-assoc...Background:Apolipoprotein E4(ApoE4)allele is the strongest genetic risk factor for late-onset Alzheimer's disease,and it can aggravate depressive symptoms in non-AD patients.However,the impact of ApoE4 on AD-associated depression-l ike behaviors and its underlying pathogenic mechanisms remain unclear.Methods:This study developed a 5xFAD mouse model overexpressing human ApoE4(E4FAD).Behavioral assessments and synaptic function tests were conducted to explore the effects of ApoE4 on cognition and depression in 5xFAD mice.Changes in peripheral and central lipid metabolism,as well as the levels of serotonin(5-HT)andγ-aminobutyric acid(GABA)neurotransmitters in the prefrontal cortex,were examined.In addition,the protein levels of 24-dehydrocholesterol reductase/glycogen synthase kinase-3 beta/mammalian target of rapamycin(DHCR24/GSK3β/m TOR)and postsynaptic density protein 95/calmodulin-dependent protein kinase II/brain-derived neurotrophic factor(PSD95/CaMK-II/BDNF)were measured to investigate the molecular mechanism underlying the effects of ApoE4 on AD mice.Results:Compared with 5xFAD mice,E4FAD mice exhibited more severe depressionlike behaviors and cognitive impairments.These mice also exhibited increased amyloid-beta deposition in the hippocampus,increased astrocyte numbers,and decreased expression of depression-related neurotransmitters 5-HT and GABA in the prefrontal cortex.Furthermore,lipid metabolism disorders were observed in E4FAD,manifesting as elevated low-density lipoprotein cholesterol and reduced high-density lipoprotein cholesterol in peripheral blood,decreased cholesterol level in the prefrontal cortex,and reduced expression of key enzymes and proteins related to cholesterol synthesis and homeostasis.Abnormal expression of proteins related to the DHCR24/GSK3β/m TOR and PSD95/CaMK-II/BDNF pathways was also observed.Conclusion:This study found that ApoE4 overexpression exacerbates depressionlike behaviors in 5xFAD mice and confirmed that ApoE4 reduces cognitive function in these mice.The mechanism may involve the induction of central and peripheral lipid metabolism disorders.Therefore,modulating ApoE expression or function to restore cellular lipid homeostasis may be a promising therapeutic target for AD comorbid with depression.This study also provided a better animal model for studying AD comorbid with depression.展开更多
文摘The carboxyl-terminal amino acids 272-299-truncated apoE4 （△272-299） is the main fragments of apoE4 hydrolysate in neurons. The effects of truncated-ApoE4 （△272-299） overexpression on tau phosphorylation in cultured N2a cells were investigated. The truncated-apoE4 （△272-299） cDNA was subcloned into pEGFP-c3 to form recombinant pEGFP-T-apoE4, pEGFP-c3, pEGFP-T- apoE4 and pEGFP-apoE4 were transfected into N2a cells respectively by lipofectamine 2000 method. After 24-48 h, tau phosphorylation was detected by Western blot assay and glycogen synthase kinase-3 （GSK-3） activity by using GSK-3 activity assay. The results showed that the overexpression of both full length-apoE4 and truncated apoE4 fragments in N2a cells induced a dramatic increase in phosphorylation of tau at Ser202 sites and the activation of GSK-3 as compared with untransfected cells, most significantly in the cells transfected with pEGFP-T-apoE4 （P〈0. 05）. It was concluded that in vitro overexpression of truncated-ApoE4 （△272-299） can result in tau hyperphosphorylation in N2a cells by activating GSK-3, suggesting truncated-ApoE4 （△272-299） might contribute the pathogenesis of Alzheimer disease.
基金supported by the Science and Technology Innovation 2030 Major Projects(2022ZD0211600)the National Natural Science Foundation of China(82271574,82071204,81871069)the Key Projects of Commission of Health,Jiangsu Province(ZDB2020008).
文摘Alzheimer's disease(AD)is a neurodegenerative disease characterized by progressive cognitive dysfunction and behavioral impairment that occurs in old age and pre-old age[1].Apolipoprotein4(ApoE4)is the most important genetic risk factor for late-onset AD[2].Peripheral apoE4 is separated from that in the CNS by the blood-brain barrier(BBB)and is abundantly produced by the liver and macrophages and released into the blood to modulate lipid-related events.
文摘To scrutinize the disorders caused by human mutant apoE7/apoE4, human apoE4 and E7 transgenic mice were established with microinjection technique to examine molecular genetic phenomena in vivo. The integration and expression of h-apoE mutant genes in transgenic mice were determined with Southern blot, Northern blot and ELISA. The current studies indicated that the transgenes and the phenotypes regarding expression of transgenes could be transmitted stably in transgenic lines. The levels of serum lipid in transgenic mice showed the characteristics of hyperlipidemia. Besides, behavior tests demonstrated the degeneration of learning and memory in transgenic mice. Short life span was observed in 2 transgenic lines. After fed with high lipid food high serum lipid was found both in normal and transgenic mice, but their mechanism regulating lipid metabolism was different. It was also verified that the human apoE mutants located at either N-terminal or C-terminal had the same pathogenesis regarding disorders of lipid metabolism in murine.
基金CAMS initiative for Innovative Medicine of China,Grant/Award Number:2021-I2M-1-034。
文摘Background:Apolipoprotein E4(ApoE4)allele is the strongest genetic risk factor for late-onset Alzheimer's disease,and it can aggravate depressive symptoms in non-AD patients.However,the impact of ApoE4 on AD-associated depression-l ike behaviors and its underlying pathogenic mechanisms remain unclear.Methods:This study developed a 5xFAD mouse model overexpressing human ApoE4(E4FAD).Behavioral assessments and synaptic function tests were conducted to explore the effects of ApoE4 on cognition and depression in 5xFAD mice.Changes in peripheral and central lipid metabolism,as well as the levels of serotonin(5-HT)andγ-aminobutyric acid(GABA)neurotransmitters in the prefrontal cortex,were examined.In addition,the protein levels of 24-dehydrocholesterol reductase/glycogen synthase kinase-3 beta/mammalian target of rapamycin(DHCR24/GSK3β/m TOR)and postsynaptic density protein 95/calmodulin-dependent protein kinase II/brain-derived neurotrophic factor(PSD95/CaMK-II/BDNF)were measured to investigate the molecular mechanism underlying the effects of ApoE4 on AD mice.Results:Compared with 5xFAD mice,E4FAD mice exhibited more severe depressionlike behaviors and cognitive impairments.These mice also exhibited increased amyloid-beta deposition in the hippocampus,increased astrocyte numbers,and decreased expression of depression-related neurotransmitters 5-HT and GABA in the prefrontal cortex.Furthermore,lipid metabolism disorders were observed in E4FAD,manifesting as elevated low-density lipoprotein cholesterol and reduced high-density lipoprotein cholesterol in peripheral blood,decreased cholesterol level in the prefrontal cortex,and reduced expression of key enzymes and proteins related to cholesterol synthesis and homeostasis.Abnormal expression of proteins related to the DHCR24/GSK3β/m TOR and PSD95/CaMK-II/BDNF pathways was also observed.Conclusion:This study found that ApoE4 overexpression exacerbates depressionlike behaviors in 5xFAD mice and confirmed that ApoE4 reduces cognitive function in these mice.The mechanism may involve the induction of central and peripheral lipid metabolism disorders.Therefore,modulating ApoE expression or function to restore cellular lipid homeostasis may be a promising therapeutic target for AD comorbid with depression.This study also provided a better animal model for studying AD comorbid with depression.
