A novel role for the Drosophila epsin (lqf) Involvement in autophagy
A novel role for the Drosophila epsin (lqf) Involvement in autophagy
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DOI：
10.4161/auto.5.5.8168
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发表时间：
2009-07-01
期刊：
影响因子：
13.3
通讯作者：
Sass, Miklos
中科院分区：
文献类型：
--
作者：
Csikos, Gyoergy;Lippai, Monika;Sass, Miklos
筛选P-元件诱导的突变株系，筛选出52个内吞或自噬潜在缺陷的品系。排除那些被20-羟基蜕皮激素治疗挽救的人后，在剩余的行中确定插入的P元件的确切位置。在L(3)S011027品系中，果蝇的液体面(Lqf)基因受到影响，该基因编码一种内切蛋白同源蛋白。我们揭示了Lqf对果蝇幼虫脂肪体细胞中的幼虫血清蛋白(LSPs)的受体介导的内吞作用是必不可少的。在L(3)S011027品系中，Lqf缺失使自噬小体不能形成，从而导致滋养细胞的破坏停止。携带Lqf-RNAi基因的转基因幼虫不能产生内吞空泡和自噬空泡，导致幼虫期延长。另一方面，Lqf蛋白显示出与Lyso Tracker Red或GFP-Atg8a标记的自噬小体的排他性共定位。利用针对LqF第5外显子的抗血清，我们证明在发育自噬开始之前，Lqf蛋白存在于脂肪体细胞核中，但此后该蛋白定位于内吞和自噬空泡区域。在Lqf突变幼虫中，抑制雷帕霉素靶标(TOR)不能恢复自噬过程和正常发育，这表明LqF位于TOR的下游，TOR是自噬途径的中心激酶。
Screening P-element-induced mutant collections, 52 lines were selected as potentially defected ones in endocytosis or autophagy. After excluding those which were rescued by 20-hydroxyecdysone treatment, the exact position of the inserted P-element was determined in the remaining lines. In the case of l(3)S011027 stock, the liquid facets (lqf) gene was affected which codes an epsin-homolog protein in Drosophila. We reveal that Lqf is essential to the receptor-mediated endocytosis of larval serum proteins (LSPs) in the larval fat body cells of Drosophila. In l(3)S011027 line, lack of Lqf fails the formation of autophagosomes thus leading to the arrest of destroying of trophocytes. Transgenic larvae carrying Lqf-RNAi construct were unable to generate endocytic and autophagic vacuoles and led to a prolonged larval stage. On the other hand, Lqf protein showed an exclusive colocalization with the Lyso Tracker Red- or GFP-Atg8a labeled autophagosomes. By using the antiserum generated against the fifth exon of lqf, we demonstrated that prior to the onset of developmental autophagy the Lqf protein was present in the nucleus of fat body cell, but thereafter the protein was localized in the territory of endocytic and autophagic vacuoles. The fact that the inhibition of the target of rapamycin (TOR) did not restore the autophagic process and the normal development in the case of lqf mutant larvae points to that the Lqf is downstream to the TOR, the central kinase of the autophagy pathway.