细胞器互作调控溶酶体完整性的机制研究

Lysosomes degrade macromolecules and recycle metabolites as well as being involved in diverse processes that regulate cellular homeostasis. The lysosome is limited by a single phospholipid bilayer that forms a barrier to separate the potent luminal hydrolases from other cellular constituents, thus protecting the latter from unwanted degradation. The mechanisms that maintain lysosomal membrane integrity, the physiological significance and the molecular machinery that controls clearance of damaged lysosomes remain unclear. Lysosomes interact with various intracellular organelles such as ER, mitochondria, peroxisome and endosomes, which plays important roles in transporting catabolites and lipids as well as regulates lysosome biogenesis and remodeling. Whether and how organelle contact is involved in maintaining lysosome membrane integrity and clearance of damaged lysosomes is not addressed. Taking advantage of the powerful genetic and cell biological tools in the nematode Caenorhabditis elegans, we aim to dissect lysosomal interaction with other intracellular organelles and determine whether and how the organelle contact regulates lysosome membrane integrity and clearance of damaged lysosomes. By monitoring lysosomes in live C. elegans, we will follow dynamic changes of lysosomes, including contact with other organelles, membrane integrity and removal of damaged lysosomes. By combinatory screen strategies, we will identify genes involved in mediating organelle contact, maintaining lysosome membrane integrity and removing damaged lysosomes, and elucidate their functions in these processes. Given the evolutionary conservation of lysosomal composition and regulation, we will determine the mammalian homologs of the C. elegans genes and investigate their functions in mammals. These studies will certainly help us to understand how lysosome integrity is maintained under physiological conditions, the role of organelle contact in this process, and how impairment of membrane integrity may contribute to the pathogenesis of lysosome-related human diseases.

溶酶体负责物质降解和循环，在机体发育及细胞稳态维持中发挥关键作用。溶酶体膜完整性缺失导致溶酶体功能缺陷及细胞死亡。溶酶体与多种细胞器发生互作,在代谢产物循环、脂类转运及自身发生、重塑等过程中发挥作用，但介导上述互作的关键蛋白及作用机制仍有待研究。另外，溶酶体完整性的维护机制、生理功能、损伤溶酶体识别及清除机制均未被解析。.本项目以秀丽线虫为模式研究细胞器互作调控溶酶体完整性的作用机制。我们已建立了溶酶体体内研究系统，可跟踪溶酶体与其他细胞器的互作及溶酶体膜完整性变化；发现了调控溶酶体完整性的关键膜蛋白SCAV-3/LIMP-2；通过遗传筛选获得多个溶酶体完整性缺陷突变体。在本项目中，我们将确定细胞器互作是否及如何调控溶酶体完整性或损伤溶酶体清除；利用遗传筛选获得调控上述过程的新基因并解析它们的作用机制。我们将研究线虫溶酶体调控基因在哺乳动物中同源基因的功能，为溶酶体相关疾病研究提供线索。

溶酶体负责物质降解与循环，并作为信号感知及应答中心在细胞稳态平衡中发挥重要作用。溶酶体膜完整性缺失导致溶酶体功能缺陷及细胞死亡。溶酶体完整性的维护机制、生理功能、损伤溶酶体识别及清除机制尚不明晰。. 在本项目中，我们建立了以线虫为模式的多细胞生物溶酶体完整性研究体系，系统研究溶酶体膜完整性的维护机制和生理功能，并探究细胞器互作是否以及如何调控溶酶体完整性或损伤溶酶体清除。我们鉴定得到多个溶酶体完整性调控基因并解析其作用机制。我们发现溶酶体底物降解在膜完整性维护中发挥关键作用。例如，溶酶体酸性水解酶RNST-2降解rRNA，保障溶酶体膜完整性，在胚胎发育及寿命调控中发挥重要作用。溶酶体氯离子通道蛋白LID-1和组织蛋白酶，保障溶酶体底物降解及膜完整性。另外，我们鉴定得到LMA-2和LID-7，解析了它们调控溶酶体膜裂解和膜循环，进而保障溶酶体完整性的作用机制。我们发现鞘脂代谢途径、线粒体和内质网信号通路参与调控溶酶体完整性。此外，我们的工作揭示了胞外基质到细胞核的信号通路，阐明其在调控溶酶体活性及维护细胞稳态平衡和机体发育中的作用；发现了多个寿命调控通路调控溶酶体功能，以及溶酶体完整性维护及活性在寿命调控中的重要作用。上述研究成果揭示了多个溶酶体完整性调控基因的作用机制及生理功能，阐明了溶酶体完整性及活性调控在机体发育和衰老过程中的功能，不仅具有重要的科学意义，也为溶酶体相关疾病的研究提供了新线索。