Aplin A, Jasionowski T, Tuttle D L, Lenk S E, Dunn W A
Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville 32610-0235.
J Cell Physiol. 1992 Sep;152(3):458-66. doi: 10.1002/jcp.1041520304.
We evaluated the role of cytoskeletal elements in the degradation of endogenous proteins via autophagy using biochemical and morphological techniques. In the absence of exogenous amino acids, degradation of endogenous proteins was enhanced in cultured normal rat kidney cells. This enhanced degradative state was accompanied by a 4-fold increase in the occurrence of autophagic vacuoles. In the presence of drugs that induce the depolymerization of microfilaments (cytochalasins B and D) or microtubules (nocodazole), protein degradation was not enhanced in nutrient-deprived cells. Although these drugs had similar inhibitory effects on the protein degradation, their effect on autophagy differed. Cytochalasins B and D interfered with the formation of the autophagosome. In cells treated with these drugs, the fractional volume represented by autophagic vacuoles was not substantially increased despite nutrient depletion. On the contrary, nocodazole appeared to have no effect on the formation of autophagosomes. Instead, this drug suppressed the delivery of hydrolytic enzymes, thereby resulting in an accumulation of acidic autophagic vacuoles containing undegraded cellular components.
我们运用生化和形态学技术评估了细胞骨架成分在自噬介导的内源性蛋白质降解中的作用。在缺乏外源性氨基酸的情况下，培养的正常大鼠肾细胞内源性蛋白质的降解增强。这种增强的降解状态伴随着自噬泡出现频率增加4倍。在存在诱导微丝解聚的药物（细胞松弛素B和D）或微管解聚的药物（诺考达唑）时，营养缺乏细胞中的蛋白质降解并未增强。尽管这些药物对蛋白质降解具有相似的抑制作用，但它们对自噬的影响有所不同。细胞松弛素B和D干扰自噬体的形成。在用这些药物处理的细胞中，尽管营养物质耗尽，但自噬泡所占的分数体积并未显著增加。相反，诺考达唑似乎对自噬体的形成没有影响。相反，这种药物抑制了水解酶的传递，从而导致含有未降解细胞成分的酸性自噬泡积累。
