Lysosomal quality control through lipid remodeling

通过脂质重塑进行溶酶体质量控制

• 批准号: 10711028
• 负责人: Xiaojun Tan
• 金额: $ 39.75万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2028-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10711028
• 关键词: 1-Phosphatidylinositol 4-Kinase; Aging; Cardiovascular Diseases; Cell Death; Cell Membrane Permeability; Cell model; Cell physiology; Cellular Stress; Chemicals; Cholesterol; Disease; Endoplasmic Reticulum; FDA approved; Family member; Functional disorder; Homeostasis; Human; Lipids; Lysosomal Storage Diseases; Lysosomes; Mediating; Membrane; Nerve Degeneration; Nutrient; Pathway interactions; Phosphatidylinositols; Phosphatidylserines; Play; Production; Protein Family; Proteins; Proteomics; Quality Control; Recycling; Role; Therapeutic; cell growth; design; human disease; improved; interest; lipid transport; lipidomics; oxysterol binding protein; phosphatidylinositol 4-phosphate; recruit; repaired; response; small molecule; small molecule libraries; stressor

Project Summary/Abstract: Lysosomes play essential roles in cell physiology, not only controlling nutrient recycling and cellular growth, but also mediating the proper handling of various cellular stress. Lysosomal dysfunction is associated with aging and many diseases such as lysosomal storage disease, neurodegeneration, and cardiovascular diseases. A hallmark of lysosomal-related diseases is lysosomal membrane permeabilization/damage (LMP) which if not immediately resolved can cause detrimental problems including cell death. We now start to understand that LMP triggers multiple cellular pathways to repair damaged lysosomes. However, none of the previously described pathways appear to be essential for rapid lysosomal repair, suggesting additional repair mechanisms. As an attempt to find such mechanism, we recently designed and executed an unbiased proteomic screen searching for proteins specifically enriched on damaged lysosomes. This screen led to the discovery of the phosphoinositide-initiated membrane tethering and lipid transport (PITT) pathway as an essential mechanism for rapid lysosomal repair. We found that LMP stimulates robust production of phosphatidylinositol-4-phosphate (PtdIns4P, PI4P) on damaged lysosomes by type II alpha phosphatidylinositol-4 kinase (PI4K2A). Lysosomal PI4P drives the formation of extensive membrane contacts between the endoplasmic reticulum (ER) and damaged lysosomes by recruiting multiple oxysterol-binding protein (OSBP)-related protein (ORP) family members. The ORPs catalyze subsequent ER-to-lysosomal transport of cholesterol and phosphatidylserine (PS) to mediate rapid membrane repair. While cholesterol by itself increases membrane stability, PS activates ATG2-mediated lipid transport for direct lysosomal repair. The PITT pathway is activated in response to diverse disease-related lysosomal-damaging conditions and is expected to have enormous impact on human pathophysiology. Remarkably, the PITT pathway not only reveals lipid transfer at membrane contacts as a essential mechanism for lysosomal repair, but it also establishes lipid remodeling as a new platform to understand lysosomal quality control. Through three independent projects in the next five years, our lab will continue studying LMP-triggered lysosomal lipid remodeling for better mechanistic understanding of lysosomal quality control and potential therapeutic applications. First, we are purifying lysosomes during and after lysosomal repair to characterize lipid changes by lipidomics, which we believe will identify new lipid messengers important for lysosomal quality control. Second, the PITT-mediated lysosomal cholesterol accumulation provides a great cellular model to study cholesterol transport, and we are particularly interested in the mechanism for cholesterol egress from newly repaired lysosomes. Finally, we are also performing chemical screens using FDA- approved chemical library to search for small molecules that activate or block the PITT pathway. The identified small molecules have well established protein targets, which will help define the regulatory networks for the PITT lysosomal quality control pathway as well as delineate new strategies to improve lysosomal quality.

项目摘要/摘要： 溶酶体在细胞生理学中起重要作用，不仅控制营养的回收和细胞生长，还可以 还介导了各种细胞应激的正确处理。溶酶体功能障碍与衰老有关 以及许多疾病，例如溶酶体储存疾病，神经退行性疾病和心血管疾病。一个 与溶酶体相关疾病的标志是溶酶体膜通透/损伤（LMP） 立即解决可能导致有害问题，包括细胞死亡。我们现在开始了解LMP 触发多种细胞途径来修复受损受损的溶酶体。但是，没有先前描述的 途径似乎对于快速溶酶体修复至关重要，这表明了其他修复机制。作为 尝试找到这种机制，我们最近设计并执行了无偏的蛋白质组学屏幕搜索 对于特异性富含受损溶酶体的蛋白质。这个屏幕导致发现 磷酸肌醇引发的膜束缚和脂质转运（PITT）途径是必不可少的机制 快速溶酶体修复。我们发现LMP刺激磷脂酰肌醇-4-磷酸的强大产生 （PTDINS4P，PI4P）在II型α磷脂酰肌醇4激酶（PI4K2A）上受损的溶酶体受损。溶酶体 PI4P驱动内质网（ER）和 通过募集多个氧化酚结合蛋白（OSBP）相关蛋白（ORP）家族而受损的溶酶体受损 成员。 ORP催化了随后的胆固醇和磷脂酰丝氨酸的ER到溶质体转运 （PS）介导快速膜修复。胆固醇本身会增加膜稳定性，而PS激活 ATG2介导的脂质转运进行直接溶酶体修复。 PITT途径被激活，以响应多样化 与疾病有关的溶酶体破坏疾病，预计将对人类产生巨大影响 病理生理学。值得注意的是，皮特途径不仅揭示了膜接触处的脂质转移作为一个 溶酶体修复的基本机制，但它也建立了脂质重塑作为新平台 了解溶酶体质量控制。通过未来五年的三个独立项目，我们的实验室将 继续研究LMP触发的溶酶体脂质重塑，以更好地理解溶酶体 质量控制和潜在的治疗应用。首先，我们在净化溶酶体期间和之后 溶酶体修复以表征通过脂质组学变化的脂质变化，我们相信这将确定新的脂质使者 对于溶酶体质量控制很重要。其次，PITT介导的溶酶体胆固醇积累提供 一个研究胆固醇传输的很好的细胞模型，我们对此特别感兴趣 来自新修复的溶酶体的胆固醇出口。最后，我们还使用FDA-进行化学屏幕 批准的化学文库搜索激活或阻止PITT途径的小分子。确定的 小分子具有良好的蛋白质靶标，这将有助于定义PITT的调节网络 溶酶体质量控制途径以及描述提高溶酶体质量的新策略。

项目成果

A conserved ion channel function of STING mediates noncanonical autophagy and cell death.

STING 的保守离子通道功能介导非典型自噬和细胞死亡。

• DOI: 10.1038/s44319-023-00045-x
• 发表时间: 2024
• 期刊: EMBO reports
• 影响因子: 7.7
• 作者: Xun,Jinrui;Zhang,Zhichao;Lv,Bo;Lu,Defen;Yang,Haoxiang;Shang,Guijun;Tan,JayXiaojun
• 通讯作者: Tan,JayXiaojun