化学
淀粉样β
淀粉样蛋白(真菌学)
基因组DNA
DNA
DNA损伤
淀粉样前体蛋白分泌酶
细胞生物学
生物物理学
分子生物学
生物化学
生物
淀粉样前体蛋白
医学
病理
阿尔茨海默病
疾病
无机化学
作者
Hrishita Das,Sukanya Sarkar,Ramesh Kumar Paidi,Subhas C. Biswas
标识
DOI:10.1096/fj.202001676rr
摘要
Aberrant accumulation of amyloid-β (Aβ) in brain is the major trigger for pathogenesis in Alzheimer's disease (AD). It is imperative to understand how Aβ attains such toxic levels in the brain parenchyma. We detected that a subtle and tolerable amount of DNA damage, related to aging, increased intraneuronal Aβ1-42 production both in cultured neuron and in cortex of rodent brain. Strikingly, we also observed elevated levels of mitochondrial fusion and of its major driver protein, MFN2. Hyperfusion of mitochondria may be seen as an adaptive stress response resulting from the induction of ER stress since we detected the activation of both PERK and IRE1α arms of unfolded protein response of ER stress. We found increased phosphorylation of PERK substrate eukaryotic initiation factor 2 α (eIF2α), and upregulation of the downstream effector proteins, ATF4 and CHOP. Concomitantly, increased XBP1 level, the direct effecter protein of IRE-1α, was observed. Reports suggest that eIF2α phosphorylation can increase BACE1 activity, the rate limiting enzyme in Aβ production. Here, we show that inhibiting PERK, decreased Aβ1-42 level while direct BACE1 inhibition, reduced the mitochondrial fusion. We found increased MFN2 expression in young 5xFAD mice when Aβ plaques and neurodegeneration were absent. Thus, our study indicates that mild DNA damage leads to increased Aβ1-42 production almost as a consequence of an initial ER stress-directed protective mitochondrial fusion in brain. We propose that an age-related subtle genomic DNA damage may trigger enhanced intraneuronal Aβ1-42 production in an apparently healthy neuron way before the appearance of clinical symptoms in AD.
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