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

年老生物体中细胞和器官的退化，至少部分是由于负责维持细胞质量控制的系统失效所致。这些监测系统的故障也是与衰老相关的严重疾病的基础，如神经变性、代谢紊乱或肌肉无力。伴侣介导的自噬（CMA）是溶酶体中选择性胞质蛋白降解的分解代谢途径，有助于细胞质量控制和维持细胞能量平衡。重要的是，CMA活性随着年龄的增长而下降，在老年啮齿动物中恢复正常的CMA活性可以改善细胞稳态并保持器官功能。最近，CMA受损的细胞被发现对内质网（ER）应激和饮食脂质挑战更敏感。在内质网和脂质储存细胞器（所谓的脂滴）上，发现了可以作为cma介导降解底物的特定蛋白质。该项目的目的是研究CMA对这些蛋白质的调节降解是否会调节内质网稳态和脂滴周转。因此，我将确定表达内质网或脂滴蛋白抗cma变体的细胞模型对内质网应激源和脂肪生成挑战的反应。这将有助于了解CMA在维持内质网稳态和动员脂滴中的作用。此外，由于内质网和脂滴共享物理和功能连接，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功能下降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.