To mediate the degradation of macromolecules delivered by endocytosis and autophagy, lysosomes must undergo extensive trafficking, including migration along microtubule tracks towards cargo-carrying endosomes and autophagosomes and subsequent membrane fusion and fission processes. Defects in lysosomal trafficking lead to lysosome storage diseases (LSDs). The long term goal of the proposed research is to understand how various cellular cues regulate lysosomal trafficking in autophagy and endocytosis. During the last funding period, we demonstrated that Ca2+ release from the lysosomal lumen plays a key signaling role in regulating multiple steps of lysosomal trafficking. By directly patch-clamping lysosomal membranes and by fluorescently imaging Ca2+ release from lysosomes, we showed that TRPML1 (transient receptor potential mucolipin 1, or ML1) is the principle Ca2+ release channel in the lysosome. By performing high-throughput screening we have identified several highly potent and selective synthetic agonists and antagonists of ML1. Whereas human mutations of TRPML1 cause a LSD characterized by disordered lysosomal trafficking, pharmacological activation of ML1 using synthetic agonists is sufficient to induce lysosomal biogenesis and trafficking. Furthermore, use of synthetic antagonists shows that ML1 is required for lysosomal exocytosis during phagocytosis and membrane repair. Our preliminary studies have identified two distinct classes of endogenous molecules that act as agonists for ML1. The central goal of this competitive renewal project is to test the hypothesis that cellular cues regulate lysosome trafficking and autophagy, by directly activating ML1 to elicit lysosomal Ca2+ release. We will use lysosome Ca2+ imaging, lysosome electrophysiology, mouse knockouts, transgenic mice, and CRISPR/Cas9 in vivo mutagenesis to test the hypothesis that boosting the activity of ML1 will facilitate lysosome biogenesis and autophagy in cells in culture, and alleviate lysosome storage and neurodegeneration in mouse models of several LSDs.
Aim 1 is to determine the role of ML1 in lysosome biogenesis and autophagy.
Aim 2 is to investigate the roles of ML1 in Ca2+-dependent lysosomal motility. Finally, we will study the in vivo effects of increasing ML1's activity on neurodegeneration associated with LSD. Our ultimate goal of this proposed research is to lay the groundwork necessary to develop new therapeutic strategies for lysosome-related pediatric and adult neurodegenerative diseases.
| Li, Ping; Gu, Mingxue; Xu, Haoxing (2018) Lysosomal Ion Channels as Decoders of Cellular Signals. Trends Biochem Sci : |
| Wang, Zhen; Ocadiz-Ruiz, Ramon; Sundaresan, Sinju et al. (2018) Isolation of Enteric Glial Cells from the Submucosa and Lamina Propria of the Adult Mouse. J Vis Exp : |
| Zhang, Xiaoli; Hu, Meiqin; Yang, Yexin et al. (2018) Organellar TRP channels. Nat Struct Mol Biol 25:1009-1018 |
| Hirano, Tomoko; Stecker, Kelly; Munnik, Teun et al. (2017) Visualization of Phosphatidylinositol 3,5-Bisphosphate Dynamics by a Tandem ML1N-Based Fluorescent Protein Probe in Arabidopsis. Plant Cell Physiol 58:1185-1195 |
| Chen, Qingfeng; She, Ji; Zeng, Weizhong et al. (2017) Structure of mammalian endolysosomal TRPML1 channel in nanodiscs. Nature 550:415-418 |
| Sahoo, Nirakar; Gu, Mingxue; Zhang, Xiaoli et al. (2017) Gastric Acid Secretion from Parietal Cells Is Mediated by a Ca2+ Efflux Channel in the Tubulovesicle. Dev Cell 41:262-273.e6 |
| Wang, Wuyang; Zhang, Xiaoli; Gao, Qiong et al. (2017) A voltage-dependent K+ channel in the lysosome is required for refilling lysosomal Ca2+ stores. J Cell Biol 216:1715-1730 |
| Sundaresan, Sinju; Meininger, Cameron A; Kang, Anthony J et al. (2017) Gastrin Induces Nuclear Export and Proteasome Degradation of Menin in Enteric Glial Cells. Gastroenterology 153:1555-1567.e15 |
| Gu, Mingxue; Xu, Haoxing (2016) A painful TR(i)P to lysosomes. J Cell Biol 215:309-312 |
| Li, Xinran; Rydzewski, Nicholas; Hider, Ahmad et al. (2016) A molecular mechanism to regulate lysosome motility for lysosome positioning and tubulation. Nat Cell Biol 18:404-17 |
Showing the most recent 10 out of 40 publications
