天然小分子LY-22阻断磷脂酰肌醇四磷酸的合成进而抑制溶酶体酸化的机制研究

溶酶体是负责细胞内物质降解和代谢调控的酸性细胞器，其酸化异常导致胞内物质堆积和人类疾病的发病。尽管人们对溶酶体功能的认识不断加强，但溶酶体酸化的机制还远未阐明。因此，揭示溶酶体酸化的调控机制是一个重要的科学问题。以小分子化合物为探针的研究不仅阐明溶酶体酸化调控的机制，并为相关疾病的治疗提供理论基础和潜在靶标。我们前期实验筛选到一类结构新颖的天然小分子LYs，其显著抑制溶酶体酸化，同时阻断磷脂酰肌醇四磷酸合成; 而外源补充磷脂酰肌醇四磷酸，可恢复LY-22损伤的溶酶体酸化。我们假说：天然小分子LY-22通过阻断磷脂酰肌醇四磷酸的合成，进而抑制溶酶体酸化和细胞自噬。本项目依托高通量化合物筛选平台，以小分子化合物为探针，结合遗传筛选、活细胞成像、蛋白质追踪定位、蛋白质修饰和相互作用等多种研究手段，阐明天然小分子抑制溶酶体酸化的作用机制，为揭示溶酶体相关疾病的发病提供新的理论依据。

Lysosomes are acidified organelles regulating degradation and metabolism within cells. Abnormality of lysosomal acidity results in cargo accumulation and severe human disorders, including neurodegenerative diseases and metabolic diseases. The mechanisms underlying acidification of lysosomes are, however, poorly understood. Using small-molecular natural compounds as probes, chemical biology provides unique approaches to reveal regulatory mechanisms of lysosomal acidification. Our preliminary studies have identified a group of natural compounds, namely LYs, which impairs lysosomal acidity and biosynthesis of phosphatidylinositol 4-phosphate (PI4P) significantly. Notably, additional complement of PI4P restores LY-22-impaired lysosomal acidification. Thus, our hypothesis is that natural compound LY-22 inhibits lysosomal acidification via interrupting PI4P biosynthesis within cells, resulting in autophagic dysfunction and accumulation of protein aggregates and lipid droplets. In this project, we plan to further investigate how these compounds function by identifying their target proteins, using a combination of approaches including genetic screen, protein-protein interactions, live-cell imaging, protein modifications, and chemical modification of compounds. This unique research will not only provide important novel insights into lysosomal acidification and homeostasis, but also reveal pathological mechanisms underlying lysosome-related human disorders.