Role for Rab7 in maturation of late autophagic vacuoles
Role for Rab7 in maturation of late autophagic vacuoles
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DOI：
10.1242/jcs.01370
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发表时间：
2004-09-15
影响因子：
4
通讯作者：
Eskelinen, EL
中科院分区：
文献类型：
--
作者：
Jäger, S;Bucci, C;Eskelinen, EL
小GTP结合蛋白Rab7在后期内吞途径和溶酶体生物发生中发挥作用。然而，哺乳动物Rab7在自噬中的作用尚不清楚。我们通过RNA干扰和显性阴性Rab7的过表达抑制Rab7的功能来解决这个问题。我们在这里表明Rab7是形成核周围大聚集体所必需的，其中自噬体标记LC3与Rab7和晚期内体和溶酶体标记共定位。通过电镜观察，我们发现这些大的聚集体对应于包围着晚期内体或溶酶体囊泡的自噬液泡。我们的定量电镜实验表明，早期自噬体向晚期自噬液泡的初始成熟不需要Rab7，但它参与了晚期自噬液泡的最终成熟。最后，我们发现，在缺乏溶酶体膜蛋白Lamp1和Lamp2的细胞中，Rab7向自噬液泡的募集被延缓，我们最近发现，在饥饿期间，这些蛋白会积累晚期的自噬液泡。总之，我们的研究结果表明Rab7在晚期自噬液泡的最终成熟中起作用。
The small GTP binding protein Rab7 has a role in the late endocytic pathway and lysosome biogenesis. The role of mammalian Rab7 in autophagy is, however, unknown. We have addressed this by inhibiting Rab7 function with RNA interference and overexpression of dominant negative Rab7. We show here that Rab7 was needed for the formation of preferably perinuclear, large aggregates, where the autophagosome marker LC3 colocalised with Rab7 and late endosomal and lysosomal markers. By electron microscopy we showed that these large aggregates corresponded to autophagic vacuoles surrounding late endosomal or lysosomal vesicles. Our experiments with quantitative electron microscopy showed that Rab7 was not needed for the initial maturation of early autophagosomes to late autophagic vacuoles, but that it participated in the final maturation of late autophagic vacuoles. Finally, we showed that the recruitment of Rab7 to autophagic vacuoles was retarded in cells deficient in the lysosomal membrane proteins Lamp1 and Lamp2, which we have recently shown to accumulate late autophagic vacuoles during starvation. In conclusion, our results showed a role for Rab7 in the final maturation of late autophagic vacuoles.