Endosomal Microautophagy in Drosophila

果蝇内体微自噬 蛋白质和细胞器的适当周转对正常细胞功能至关重要。 受损或改变的胞质蛋白通过蛋白酶体和自噬被清除。 重要的是，自噬还有一个额外的作用，即在压力下为细胞提供营养 在饥饿等条件下，它是能量平衡所必需的。肝脏是一个 是体内脂质的主要调节剂，在代谢中起重要作用， 异源生成是一个特别依赖于由异源生成的氨基酸的过程， 在饥饿或应激下细胞蛋白质的自噬降解。此外，委员会认为， 清除受损的细胞器和聚集的蛋白质对保护肝脏至关重要， 肾脏对年龄相关的疾病。 大自噬（MA）、伴侣介导的自噬（CMA）和内体自噬（CMA） 微自噬（Microautophagy，eMI）是自噬的三种主要形式。MA吞没体区域 细胞质包括细胞器在一个双膜囊泡（自噬体）。 自噬体与溶酶体融合导致被吞噬物质的降解。 对CMA和eMI的了解较少，它们主要降解含有 靶向基序（KFERQ相关序列），其被细胞质Hsc 70识别。 在eMI期间，迄今为止仅通过生物化学和EM表征， 含有与Hsc 70结合的底物的KFERQ被吸收到多泡 体/晚期内体在ESCRT机器依赖性过程中降解。 以前，哺乳动物以外的eMI的存在是未知的，目前有 没有研究哺乳动物eMI的体内系统。因此，模型的遗传力量 诸如果蝇之类的生物尚未被用于KFERQ的研究， 自噬的依赖形式。 使用在转基因果蝇中表达的荧光标记的模型底物，我们 开发了一个模型系统，以研究饥饿诱导的eMI在体内。使用这个系统， 我们将通过饥饿和其他方法评估eMI的生理功能和调节， 细胞压力的形式。此外，我们将描述eMI的监管机构，我们 在基因筛查中发现的。

Endosomal Microautophagy in Drosophila Proper turnover of proteins and organelles is essential for normal cell function. Damaged or altered cytosolic proteins are cleared by the proteasome and autophagy. Importantly, autophagy has the additional role of providing nutrients to cells under stress conditions such as starvation, and is thus essential for energy balance. The liver is one of the main regulators of lipids in the body and has major roles in metabolism such as gluconeogenesis, a process that is particularly dependent on amino acids generated by autophagic degradation of cellular proteins under starvation or stress. Furthermore, removal of damaged organelles and aggregated proteins is essential to protect liver and kidneys against age related disorders. Macroautophagy (MA), Chaperone mediated Autophagy (CMA) and endosomal Microautophagy (eMI) are the three major forms of autophagy. MA engulfs bulk-regions of cytoplasm including organelles in a double membrane vesicle (autophagosome). Autophagosome fusion with lysosomes leads to the degradation of the engulfed material. Less is known about CMA and eMI, which mostly degrade proteins containing a targeting motif (KFERQ related sequences) that is recognized by the cytoplasmic Hsc70. During eMI, which to date has only been characterized biochemically and by EM, KFERQ containing substrates bound to Hsc70 are taken up into multivesicular bodies/late endosomes in an ESCRT machinery dependent process and degraded. Previously, the existence of eMI beyond mammals was unknown and there is currently no in vivo system to study mammalian eMI. Hence, the genetic power of model organisms such as Drosophila have not been exploited for the study of KFERQ- dependent forms of autophagy. Using a fluorescently tagged model substrate expressed in transgenic flies, we developed a model system to study starvation inducible eMI in vivo. Using this system, we will assess the physiological function and regulation of eMI by starvation and other forms of cellular stress. Furthermore, we will characterize regulators of eMI that we have identified in a genetic screen.