Characterizing the contribution of chaperone-mediated autophagy to endoplasmic reticulum and lipid droplet homeostasis.

老生物体的细胞和器官退化至少部分是由于负责维持细胞质量控制的系统的故障造成的。这些监测系统的故障也是与衰老相关的严重疾病的基础，如神经退化、代谢紊乱或肌肉无力。伴侣介导的自噬(CMA)是一种降解溶酶体中选择性胞浆蛋白的分解代谢途径，有助于控制细胞质量和维持细胞能量平衡。重要的是，CMA活性随着年龄的增长而降低，恢复老年啮齿动物正常的CMA活性可以改善细胞动态平衡，保护器官功能。最近，CMA受损的细胞被发现对内质网(ER)应激更敏感，并对饮食脂类发起挑战。在内质网和脂类储存细胞器，即所谓的脂滴中，都发现了特定的蛋白质，可以作为CMA介导的降解的底物。拟议项目的目的是调查CMA对这些蛋白质的调节降解的变化是否调节内质网的动态平衡和脂滴周转。因此，我将确定表达CMA抗性内质网或脂滴蛋白变体的细胞模型对内质网应激源和造脂挑战的反应。这将有助于理解CMA在维持内质网稳态和动员脂滴中的作用。此外，由于内质网和脂滴都有物理和功能上的联系，这些结果也可以用来表征CMA对这些细胞器的影响之间可能的相互作用。了解CMA受损对个体细胞过程的影响对于阐明CMA功能衰退如何导致衰老和衰老相关疾病非常重要。

Cellular and organ deterioration in old organisms results, at least in part, from a failure of the systems responsible for the maintenance of cellular quality control. Malfunctioning of these surveillance systems also underlies the basis of severe diseases associated with aging such as neurodegeneration, metabolic disorders or muscle weakness. Chaperone-mediated autophagy (CMA) is a catabolic pathway for the degradation of selective cytosolic proteins in lysosomes that contributes to cellular quality control and maintenance of the cellular energetic balance. Importantly, CMA activity decreases with age and restoring normal CMA activity in aged rodents improves cellular homeostasis and preserves organ function. Recently, cells with compromised CMA were found to be more sensitive to endoplasmic reticulum (ER) stress and to challenge with dietary lipids. In both the ER and on lipid storage organelles, so-called lipid droplets, specific proteins were identified that can be substrates for CMA-mediated degradation. The aim of the proposed project is to investigate if changes in the regulated degradation of these proteins by CMA modulate ER homeostasis and lipid droplet turnover. Therefore, I will determine the reaction of cellular models, expressing CMA-resistant variants of the ER or lipid droplet proteins, to ER stressors and lipogenic challenges. This will help to understand the role of CMA in the maintenance of ER homeostasis and mobilization of lipid droplets. Furthermore, because the ER and lipid droplets share both physical and functional connections these results can also be utilized to characterize the possible interplay between the effects of CMA on these organelles. Understanding the impact of compromised CMA on individual cellular processes is important to elucidate how functional decline of CMA contributes to aging and aging-associated disorders.