Studies on the mechanisms of autophagy: maturation of the autophagic vacuole.
Studies on the mechanisms of autophagy: maturation of the autophagic vacuole.
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DOI：
10.1083/jcb.110.6.1935
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发表时间：
1990-06
期刊：
影响因子：
--
通讯作者：
Dunn WA Jr
中科院分区：
文献类型：
--
作者：
Dunn WA Jr
随附论文中的数据表明，新生的自噬液泡是由RER形成的（Dunn， W. A. 1990）。细胞生物学杂志。110:1923- 1933。在本报告中，采用形态学和生化方法结合免疫探针，研究了新形成或新生的自噬液泡向降解液泡的成熟过程。在形成的15分钟内，自噬液泡获得酸水解酶和溶酶体膜蛋白，从而成为降解液泡。先前描述的自噬液泡类型也被确定为具有新生液泡和降解液泡的特征，但与溶酶体不同。与溶酶体相比，这个中间隔室只含有少量的组织蛋白酶L，并由双膜结合，这是新生液泡的典型特征。然而，与可与降解液泡相媲美的新生液泡不同，这些液泡是酸性的，并且在外限制膜上含有溶酶体膜蛋白lgp120。结果与逐步获得溶酶体膜蛋白和水解酶一致。甘露糖-6-磷酸受体在自噬液泡中的存在表明该受体可能在高尔基体新合成的水解酶的传递中起作用。然而，在甲硝唑胺梯度分离的自噬液泡制备中，tunicamycin对成熟酸水解酶的数量没有显著影响。综上所述，结果表明新生的自噬液泡以逐步的方式成熟为降解液泡：(a)通过与缺乏水解酶的囊泡融合获得溶酶体膜蛋白（例如，溶酶体前体）；(b)液泡酸化；(c)通过与先前存在的溶酶体或高尔基体衍生的囊泡融合获得水解酶。
Data presented in the accompanying paper suggests nascent autophagic vacuoles are formed from RER (Dunn, W. A. 1990. J. Cell Biol. 110:1923- 1933). In the present report, the maturation of newly formed or nascent autophagic vacuoles into degradative vacuoles was examined using morphological and biochemical methods combined with immunological probes. Within 15 min of formation, autophagic vacuoles acquired acid hydrolases and lysosomal membrane proteins, thus becoming degradative vacuoles. A previously undescribed type of autophagic vacuole was also identified having characteristics of both nascent and degradative vacuoles, but was different from lysosomes. This intermediate compartment contained only small amounts of cathepsin L in comparison to lysosomes and was bound by a double membrane, typical of nascent vacuoles. However, unlike nascent vacuoles vet comparable to degradative vacuoles, these vacuoles were acidic and contained the lysosomal membrane protein, lgp120, at the outer limiting membrane. The results were consistent with the stepwise acquisition of lysosomal membrane proteins and hydrolases. The presence of mannose-6-phosphate receptor in autophagic vacuoles suggested a possible role of this receptor in the delivery of newly synthesized hydrolases from the Golgi apparatus. However, tunicamycin had no significant effect on the amount of mature acid hydrolases present in a preparation of autophagic vacuoles isolated from a metrizamide gradient. Combined, the results suggested nascent autophagic vacuoles mature into degradative vacuoles in a stepwise fashion: (a) acquisition of lysosomal membrane proteins by fusing with a vesicle deficient in hydrolytic enzymes (e.g., prelysosome); (b) vacuole acidification; and (c) acquisition of hydrolases by fusing with preexisting lysosomes or Golgi apparatus- derived vesicles.