PI3K/AKT/mTOR通路
胰岛素受体
神经退行性变
蛋白激酶B
磷酸化
蛋白质稳态
细胞生物学
生物
平衡
激酶
信号转导
葡萄糖稳态
mTORC1型
胰岛素
化学
内科学
内分泌学
胰岛素抵抗
医学
疾病
作者
Cora O’Neill,Aoife P. Kiely,Meghan F. Coakley,Sean Manning,Caitríona M. Long-Smith
出处
期刊:Biochemical Society Transactions
[Portland Press]
日期:2012-07-20
卷期号:40 (4): 721-727
被引量:130
摘要
The quality control of protein homoeostasis deteriorates with aging, causing the accumulation of misfolded proteins and neurodegeneration. Thus, in AD (Alzheimer's disease), soluble oligomers, protofibrils and fibrils of the Aβ (amyloid β-peptide) and tau protein accumulate in specific brain regions. This is associated with the progressive destruction of synaptic circuits controlling memory and higher mental function. The primary signalling mechanisms that (i) become defective in AD to alter the normal proteostasis of Aβ and tau, and (ii) initiate a pathophysiological response to cause cognitive decline, are unclear. The IIS [insulin/IGF-1 (insulin-like growth factor 1)-like signalling] pathway is mechanistically linked to longevity, protein homoeostasis, learning and memory, and is emerging to be central to both (i) and (ii). This pathway is aberrantly overactivated in AD brain at the level of increased activation of the serine/threonine kinase Akt and the phosphorylation of its downstream targets, including mTOR (mammalian target of rapamycin). Feedback inhibition of normal insulin/IGF activation of the pathway also occurs in AD due to inactivation of IRS-1 (insulin receptor substrate 1) and decreased IRS-1/2 levels. Pathogenic forms of Aβ may induce aberrant sustained activation of the PI3K (phosphoinositide 3-kinase)/Akt signal in AD, also causing non-responsive insulin and IGF-1 receptor, and altered tau phosphorylation, conformation and function. Reducing IIS activity in animal models by decreasing IGF-1R levels or inhibiting mTOR activity alters Aβ and tau protein homoeostasis towards less toxic protein conformations, improves cognitive function and extends healthy lifespan. Thus normalizing IIS dysfunction may be therapeutically relevant in abrogating Aβ and tau proteotoxicity, synaptic dysfunction and cognitive decline in AD.
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