分类： 生物学 >> 生物物理学 >> 细胞生物学 提交时间： 2016-05-12
Wei, Yan
Han, Chanshuai
Wang, Yujing
Wu, Beibei
Su, Tao
Liu, Ying
He, Rongqiao
Wang, Yujing
Wu, Beibei
Liu, Ying
He, Rongqiao
摘要： Type 2 diabetes mellitus (T2DM) is regarded as one of the serious risk factors for age-related cognitive impairment; however, a causal link between these two diseases has so far not been established. It was recently discovered that, apart from high D-glucose levels, T2DM patients also display abnormally high concentrations of uric D-ribose. Here, we show for the first time that the administration of D-ribose, the most active glycator among monosaccharides, produces high levels of advanced glycation end products (AGEs) and, importantly, triggers hyperphosphorylation of Tau in the brain of C57BL/6 mouse and neuroblastoma N2a cells. However, the administration of D-glucose showed no significant changes in Tau phosphorylation under the same experimental conditions. Crucially, suppression of AGE formation using an AGEs inhibitor (aminoguanidine) effectively prevents hyperphosphorylation of Tau protein. Further study shows AGEs resulted from ribosylation activate calcium-/calmodulin-dependent protein kinase type II (CaMKII), a key kinase responsible for Tau hyperphosphorylation. These data suggest that there is indeed a mechanistic link between ribosylation and Tau hyperphosphorylation. Targeting ribosylation by inhibiting AGE formation may be a promising therapeutic strategy to prevent Alzheimer's disease-like Tau hyperphosphorylation and diabetic encephalopathies.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-11
Tong, Zhiqian
Han, Chanshuai
Qiang, Min
Wu, Beibei
Su, Tao
Liu, Ying
He, Rongqiao
Tong, Zhiqian
Wang, Xiaomin
He, Rongqiao
Han, Chanshuai
Qiang, Min
Wu, Beibei
Su, Tao
Wang, Weishan
Lv, Jihui
Zhang, Shouzi
Luo, Wenhong
Li, Hui
Luo, Hongjun
摘要： Hippocampus-related topographic amnesia is the most common symptom of memory disorders in Alzheimer's disease (AD) patients. Recent studies have revealed that experience-mediated DNA methylation, which is regulated by enzymes with DNA methyltransferase (DNMT) activity, is required for the formation of recent memory as well as the maintenance of remote memory. Notably, overexpression of DNMT3a in the hippocampus can reverse spatial memory deficits in aged mice. However, a decline in global DNA methylation was found in the autopsied hippocampi of patients with AD. Exactly, what endogenous factors that affect DNA methylation still remain to be elucidated. Here, we report a marked increase in endogenous formaldehyde levels is associated with a decline in global DNA methylation in the autopsied hippocampus from AD patients. In vitro and in vivo results show that formaldehyde in excess of normal physiological levels reduced global DNA methylation by interfering DNMTs. Interestingly, intrahippocampal injection of excess formaldehyde before spatial learning in healthy adult rats can mimic the learning difficulty of early stage of AD. Moreover, injection of excess formaldehyde after spatial learning can mimic the loss of remote spatial memory observed in late stage of AD. These findings suggest that aging-associated formaldehyde contributes to topographic amnesia in AD patients. (C) 2015 Elsevier Inc. All rights reserved.
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