Endosomal Microautophagy in Drosophila

果蝇体内的微自噬现象 蛋白质和细胞器的适当周转对细胞的正常功能至关重要。 受损或改变的胞浆蛋白被蛋白酶体和自噬清除。 重要的是，自噬还有为处于压力下的细胞提供营养的额外作用。 例如饥饿等条件，因此对能量平衡至关重要。肝是一体的 是体内脂质的主要调节剂，并在新陈代谢中发挥重要作用，如 糖异生，这一过程特别依赖于由 细胞蛋白质在饥饿或应激状态下的自噬降解。此外， 清除受损的细胞器和聚集的蛋白质对于保护肝脏和 肾脏可预防与年龄相关的疾病。 巨噬细胞自噬、伴侣介导的自噬和内噬 微自噬(EMI)是自噬的三种主要形式。马云吞没了大片区域 指细胞质，包括双层膜泡(自噬)中的细胞器。 自噬小体与溶酶体的融合导致被吞噬的物质的降解。 人们对CMA和EMI知之甚少，它们主要降解含有 靶向基序(KFERQ相关序列)，由细胞质Hsc70识别。 在EMI期间，到目前为止只有生化和EM表征， 含有与Hsc70结合的底物的KFERQ被吸收成多泡 小体/晚期内体在ESCRT机械依赖的过程中被降解。 此前，除了哺乳动物之外，EMI的存在尚不清楚，目前有 没有活体系统来研究哺乳动物的EMI。因此，模型的遗传力 果蝇等生物还没有被利用来研究KFERQ- 依赖形式的自噬。 利用转基因果蝇中表达的荧光标记模型底物，我们 开发了一个模型系统来研究体内饥饿诱导的电磁干扰。使用这个系统， 我们将评估饥饿和其他因素对EMI的生理功能和调节 各种形式的细胞压力。此外，我们将描述EMI的监管机构，即我们 已经在基因筛查中确认了。

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.