Inhibition of autophagy with 3-methyladenine results in impaired turnover of lysosomes and accumulation of lipofuscin-like material
Inhibition of autophagy with 3-methyladenine results in impaired turnover of lysosomes and accumulation of lipofuscin-like material
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DOI：
10.1078/0171-9335-00433
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发表时间：
2004-10-01
影响因子：
6.6
通讯作者：
Terman, A
中科院分区：
文献类型：
--
作者：
Stroikin, Y;Dalen, H;Terman, A
自噬（包括宏观、微观和伴侣介导的自噬）是降解受损/过时的大分子和细胞器的重要生物学机制。然而，衰老的非分裂细胞逐渐积累氧化蛋白，有缺陷的细胞器和溶酶体内脂褐素内含物，表明自噬的内在不足。为了进一步了解巨噬在细胞器更新和脂褐素形成中的作用，我们用3-甲基腺嘌呤（3ma）抑制生长受阻的人成纤维细胞（细胞衰老的经典模型）的自噬隔离。这种处理导致改变的溶酶体的显著积累，表现出脂褐素样的自身荧光，以及线粒体的适度增加，膜电位降低。在3ma暴露后，晚期内体腔室的大小似乎没有明显改变。当3ma与高氧联合使用时，脂褐素样物质的积累增强。研究结果表明，巨噬对溶酶体的正常周转至关重要。这一观点得到了文献报道的支持，包括溶酶体和/或晚期内体内的溶酶体膜蛋白，以及在vinocyastine诱导的溶酶体和自噬体融合阻断后，自噬体内水解酶活跃的溶酶体。数据还表明，溶酶体的特定成分，如膜和蛋白质，可能是脂褐素的直接来源。
Autophagy (which includes macro-, micro-, and chaperone-mediated autophagy) is an important biological mechanism for degradation of damaged/obsolete macromolecules and organelles. Ageing non-dividing cells, however, progressively accumulate oxidised proteins, defective organelles and intrallysosomal lipofuscin inclusions, suggesting inherent insufficiency of autophagy. To learn more about the role of macroautophagy in the turnover of organelles and lipofuscin formation, we inhibited autophagic sequestration with 3-methyladenine (3 MA) in growth-arrested human fibroblasts, a classical model of cellular ageing. Such treatment resulted in a dramatic accumulation of altered lysosomes, displaying lipofuscin-like autofluorescence, as well as in a moderate increase of mitochondria with lowered membrane potential. The size of the late endosomal compartment appeared not to be significantly altered following 3 MA exposure. The accumulation of lipofuscin-like material was enhanced when 3 MA administration was combined with hyperoxia. The findings suggest that macroautophagy is essential for normal turnover of lysosomes. This notion is supported by reports in the literature of lysosomal membrane proteins inside lysosomes and/or late endosomes, as well as lysosomes with active hydrolases within autophagosomes following vinblastine-induced block of fusion between lysosomes and autophagosomes. The data also suggest that specific components of lysosomes, such as membranes and proteins, may be direct sources of lipofuscin.