Suresh S N, Verma Vijaya, Sateesh Shruthi, Clement James P, Manjithaya Ravi
Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bengaluru 560 064, India.
J Genet. 2018 Jul;97(3):679-701.
A proteostasis view of neurodegeneration (ND) identifies protein aggregation as a leading causative reason for damage seen at the cellular and organ levels. While investigative therapies that aim at dissolving aggregates have failed, and the promises of silencing expression of ND associated pathogenic proteins or the deployment of engineered induced pluripotent stem cells (iPSCs) are still in the horizon, emerging literature suggests degrading aggregates through autophagy-related mechanisms hold the current potential for a possible cure. Macroautophagy (hereafter autophagy) is an intracellular degradative pathway where superfluous or unwanted cellular cargoes (such as peroxisomes, mitochondria, ribosomes, intracellular bacteria and misfolded protein aggregates) are wrapped in double membrane vesicles called autophagosomes that eventually fuses with lysosomes for their degradation. The selective branch of autophagy that deals with identification, capture and degradation of protein aggregates is called aggrephagy. Here, we cover the workings of aggrephagy detailing its selectivity towards aggregates. The diverse cellular adaptors that bridge the aggregates with the core autophagy machinery in terms of autophagosome formation are discussed. In ND, essential protein quality control mechanisms fail as the constituent components also find themselves trapped in the aggregates. Thus, although cellular aggrephagy has the potential to be upregulated, its dysfunction further aggravates the pathogenesis. This phenomenonwhen combined with the fact that neurons can neither dilute out the aggregates by cell division nor the dead neurons can be replaced due to low neurogenesis, makes a compelling case for aggrephagy pathway as a potential therapeutic option.
神经退行性变（ND）的蛋白质稳态观点认为，蛋白质聚集是在细胞和器官水平上所见损伤的主要致病原因。虽然旨在溶解聚集体的研究性疗法已告失败，沉默与ND相关的致病蛋白表达或应用工程化诱导多能干细胞（iPSC）的前景仍未实现，但新出现的文献表明，通过自噬相关机制降解聚集体目前具有治愈的潜力。巨自噬（以下简称自噬）是一种细胞内降解途径，其中多余或不需要的细胞货物（如过氧化物酶体、线粒体、核糖体、细胞内细菌和错误折叠的蛋白质聚集体）被包裹在称为自噬体的双膜囊泡中，自噬体最终与溶酶体融合以进行降解。自噬的选择性分支负责识别、捕获和降解蛋白质聚集体，称为聚集体自噬。在这里，我们阐述聚集体自噬的作用机制，详细说明其对聚集体的选择性。讨论了在自噬体形成方面将聚集体与核心自噬机制联系起来的各种细胞衔接子。在ND中，由于组成成分也被困在聚集体中，基本的蛋白质质量控制机制失效。因此，尽管细胞聚集体自噬有上调的潜力，但其功能障碍会进一步加重发病机制。这种现象，再加上神经元既不能通过细胞分裂稀释聚集体，也不能因神经发生低而替换死亡神经元这一事实，使得聚集体自噬途径成为一种潜在治疗选择的有力理由。
