FBS Colloquia No.281Laboratory of Intracellular Membrane Dynamics
| Seminar or Lecture |
1. Development of novel assay for lysophagy Takayuki Shima [Project Researcher, Yoshimori Lab] 2. Towards structural analysis of the TRPML1 complex required for local and transient Ca2+ release from the lysosomal lumen to the cytoplasm Tatsuya KAMINISHI [Assistant Professor, Yoshimori Lab] |
|---|---|
| Date and Time | 14 Oct. 2021 (Thu), 12:15～13:00 |
| Place | Online (Zoom) | An email will be sent with the meeting URL, ID, and password to all FBS members. |
| Language | Japanese |
| Contact |
Maho Hamasaki |
1. Development of novel assay for lysophagy
Lysosome, intracellular acidic organelle responsible for the degradation of cellular components, has many kinds hydrolases and involved in various cellular functions and human diseases. Lysosomal membrane rupture is induced by intracellular and extracellular factors such as, oxidative stress, silica, monosodium urate, bacterial toxins. Leaking lysosomes are a potentially harmful and stressful event for cells. Lysophagy, is remove the damaged lysosomes, contributing to maintain lysosomal homeostasis, is one of crucial lysosomal damage response. However, what and how damaged lysosome are recognized and sequestered by autophagosome during lysophagy still remains unclear. In this study, we developed new lysophagy specific assay by using fluorescent protein mKeima. We further found that the dynamics of damaged lysosome during lysophagy and identified crucial autophagy receptor protein.
2. Towards structural analysis of the TRPML1 complex required for local and transient Ca2+ release from the lysosomal lumen to the cytoplasm
The lysosome is an organelle that degrades substrates of both intracellular and extracellular origin. It also fuses with the plasma membrane to release their contents to the outside of the cell (lysosomal exocytosis), thereby playing an important role in cell differentiation and the progression of cancer and neurodegenerative diseases. Lysosomal exocytosis is a Ca2+-dependent process that requires Ca2+ stored in the lysosomal lumen to be released into the cytoplasm via TRPML1, a major Ca2+ channel on the lysosomal membrane. In addition, our laboratory has recently found that Ca2+ release by TRPML1 is also crucial in lysophagy, a type of autophagy that specifically targets damaged lysosomes (Nakamura et al., Nat Cell Biol. 2020 Oct;22(10): 1252-1263). Interestingly, lipidated LC3 or LC3-II, a well-known marker protein for autophagosomes, binds to TRPML1, thereby promoting the Ca2+ release. In this study, we aim to elucidate the cryo-EM structure of the complex formed by TRPML1 and LC3-II, and to establish the structural basis for the mechanism by which LC3-II promotes channel opening of TRPML1. The current status will be presented.
