Alzheimer’s disease is characterized by the extracellular accumulation of the amyloidβin the form of amyloid plaques and the intracellular deposition of the microtubule-associated protein tau in the form of neurofib...Alzheimer’s disease is characterized by the extracellular accumulation of the amyloidβin the form of amyloid plaques and the intracellular deposition of the microtubule-associated protein tau in the form of neurofibrillary tangles.Most of the Alzheimer’s drugs targeting amyloidβhave been failed in clinical trials.Particularly,tau pathology connects greatly in the pathogenesis of Alzheimer’s disease.Tau protein enhances the stabilization of microtubules that leads to the appropriate function of the neuron.Changes in the quantity or the conformation of tau protein could affect its function as a microtubules stabilizer and some of the processes wherein it is involved.The molecular mechanisms leading to the accumulation of tau are principally signified by numerous posttranslational modifications that change its conformation and structural state.Therefore,aberrant phosphorylation,as well as truncation of tau protein,has come into focus as significant mechanisms that make tau protein in a pathological entity.Furthermore,the shape-shifting nature of tau advocates to comprehend the progression of Alzheimer’s disease precisely.In this review,we emphasize the recent studies about the toxic and shape-shifting nature of tau in the pathogenesis of Alzheimer’s disease.展开更多
OBJECTIVE Currently, almost all chemical compounds or biological reagents to reverse or slow down the AD process have failed in clinical trials. An integrative and multi-targeted strategy is increasingly appreciated t...OBJECTIVE Currently, almost all chemical compounds or biological reagents to reverse or slow down the AD process have failed in clinical trials. An integrative and multi-targeted strategy is increasingly appreciated to effectively combat this devastating disease. Traditional Chinese medicine(TCM) has been widely used for treatment of dementia, and thus the advantages of the potential therapeutic features of TCM treatment and associated mechanisms should be well taken. The Amnesia Remedy Formula(ARF) was invented by one of the most influential Master of TCM SUN Si-miao, who lived for about 100 year old. The aim of this research is to characterize the time course changes of the cognitive behaviors post a ARF, and the mechanism underlying the effects, focusing on PKA-centered signaling for both enhancement of neural plasticity and clearance of the phosphorylated Tau. RESULTS We tested the efficacy of ARF on two animal models of AD, and examine the central role of PKA signaling in the enhancement of neural plasticity via PKA/CREB/BDNF pathway as well as clearance of toxic p Tau via PKA/GSK3β/p Tau pathway. In the scopolamine model, ARF effectively reversed the memory in Morris water maze(MWM) test, with some features superior to anti-AD drug donepezil. In a battery test of MWM, novel object recognition or T maze in 5-month-old senescenceaccelerated mouse prone 8(SAMP8) strain mice, two weeks of administration of ARF showed overall better improvement in memory loss than donepezil, and the effect lasted for at least 1 week after termination of administration of the formula. ARF increased expression of PKA/CREB/BDNF and synaptic proteins PSD95 expression, as well as enhanced Ser9 phosphorylation of GSK3β, thus reduced p Tau in the hippocampus. Blockade of PKA signaling blunted the anti-AD-like effect of ARF, with reversal of CREB/BDNF signaling. Transcriptomic analysis indicated some changes of novel molecules along this pathway may be part of the pathological and therapeutic mechanism, which warrants further investigation. CONCLUSION ARF may display some advantageous features in treating AD with early onset, via multi-targeted manner including enhancement of neural plasticity and reduction in Tau toxicity.展开更多
As a major microtubule-associated protein, tau plays an important role in promoting microtubule assembly and stabilizing microtubules. In Alzheimer’s disease(AD) and other tauopathies, the abnormally hyperphosphoryla...As a major microtubule-associated protein, tau plays an important role in promoting microtubule assembly and stabilizing microtubules. In Alzheimer’s disease(AD) and other tauopathies, the abnormally hyperphosphorylated tau proteins are aggregated into paired helical filaments and accumulated in the neurons with the form of neurofibrillary tangles. An imbalanced regulation in protein kinases and protein phosphatases is the direct cause of tau hyperphosphorylation. Among various kinases and phosphatases, glycogen synthase kinase-3β(GSK-3β) and protein phosphatase 2A(PP2A) are the most implicated. Accumulation of the hyperphosphorylated tau induces synaptic toxicity and cognitive impairments. Here, we review the upstream factors or pathways that can regulate GSK-3β or PP2A activity mainly based on our recent findings. We will also discuss the mechanisms that may underlie tau-induced synaptic toxicity.展开更多
基金the support by the Pharmakon Neuroscience Research Network, Dhaka, Bangladesh
文摘Alzheimer’s disease is characterized by the extracellular accumulation of the amyloidβin the form of amyloid plaques and the intracellular deposition of the microtubule-associated protein tau in the form of neurofibrillary tangles.Most of the Alzheimer’s drugs targeting amyloidβhave been failed in clinical trials.Particularly,tau pathology connects greatly in the pathogenesis of Alzheimer’s disease.Tau protein enhances the stabilization of microtubules that leads to the appropriate function of the neuron.Changes in the quantity or the conformation of tau protein could affect its function as a microtubules stabilizer and some of the processes wherein it is involved.The molecular mechanisms leading to the accumulation of tau are principally signified by numerous posttranslational modifications that change its conformation and structural state.Therefore,aberrant phosphorylation,as well as truncation of tau protein,has come into focus as significant mechanisms that make tau protein in a pathological entity.Furthermore,the shape-shifting nature of tau advocates to comprehend the progression of Alzheimer’s disease precisely.In this review,we emphasize the recent studies about the toxic and shape-shifting nature of tau in the pathogenesis of Alzheimer’s disease.
文摘OBJECTIVE Currently, almost all chemical compounds or biological reagents to reverse or slow down the AD process have failed in clinical trials. An integrative and multi-targeted strategy is increasingly appreciated to effectively combat this devastating disease. Traditional Chinese medicine(TCM) has been widely used for treatment of dementia, and thus the advantages of the potential therapeutic features of TCM treatment and associated mechanisms should be well taken. The Amnesia Remedy Formula(ARF) was invented by one of the most influential Master of TCM SUN Si-miao, who lived for about 100 year old. The aim of this research is to characterize the time course changes of the cognitive behaviors post a ARF, and the mechanism underlying the effects, focusing on PKA-centered signaling for both enhancement of neural plasticity and clearance of the phosphorylated Tau. RESULTS We tested the efficacy of ARF on two animal models of AD, and examine the central role of PKA signaling in the enhancement of neural plasticity via PKA/CREB/BDNF pathway as well as clearance of toxic p Tau via PKA/GSK3β/p Tau pathway. In the scopolamine model, ARF effectively reversed the memory in Morris water maze(MWM) test, with some features superior to anti-AD drug donepezil. In a battery test of MWM, novel object recognition or T maze in 5-month-old senescenceaccelerated mouse prone 8(SAMP8) strain mice, two weeks of administration of ARF showed overall better improvement in memory loss than donepezil, and the effect lasted for at least 1 week after termination of administration of the formula. ARF increased expression of PKA/CREB/BDNF and synaptic proteins PSD95 expression, as well as enhanced Ser9 phosphorylation of GSK3β, thus reduced p Tau in the hippocampus. Blockade of PKA signaling blunted the anti-AD-like effect of ARF, with reversal of CREB/BDNF signaling. Transcriptomic analysis indicated some changes of novel molecules along this pathway may be part of the pathological and therapeutic mechanism, which warrants further investigation. CONCLUSION ARF may display some advantageous features in treating AD with early onset, via multi-targeted manner including enhancement of neural plasticity and reduction in Tau toxicity.
文摘As a major microtubule-associated protein, tau plays an important role in promoting microtubule assembly and stabilizing microtubules. In Alzheimer’s disease(AD) and other tauopathies, the abnormally hyperphosphorylated tau proteins are aggregated into paired helical filaments and accumulated in the neurons with the form of neurofibrillary tangles. An imbalanced regulation in protein kinases and protein phosphatases is the direct cause of tau hyperphosphorylation. Among various kinases and phosphatases, glycogen synthase kinase-3β(GSK-3β) and protein phosphatase 2A(PP2A) are the most implicated. Accumulation of the hyperphosphorylated tau induces synaptic toxicity and cognitive impairments. Here, we review the upstream factors or pathways that can regulate GSK-3β or PP2A activity mainly based on our recent findings. We will also discuss the mechanisms that may underlie tau-induced synaptic toxicity.
