|Start Date / Time||February 18, 2015 at 9:00 AM|
|End Date / Time||February 18, 2015 at 9:55 AM|
|Location||512 Light Hall|
|Presenter Name||Xiaodong Zhu (Kaverina lab)|
|Presentation Title||Microtubules negatively regulate insulin secretion in pancreatic β cells|
|Status||This meeting has already occurred|
Glucose-stimulated insulin secretion (GSIS) from pancreatic β cells has to be tightly regulated to maintain glucose homeostasis. A hypothesis that microtubules (MTs) transport insulin granules to exocytic sites has been a matter of debate. Here, we report that MTs regulate insulin secretion by restraining excessive delivery of insulin granules to the plasma membrane. We found that MTs in β cells emerge from the Golgi and form a meshwork that anchors insulin granules . Furthermore, we show that instead of directional transportation, insulin granules are randomly walking in the cytoplasm. Both actin and MTs contribute to such movement. Interestingly, MT depolymerization facilitates delivery of insulin to the cell membrane and dramatically enhances GSIS, suggesting that MTs withhold granules away from secretion sites and that glucose induces dynamic MT turnover for GSIS to occur. Our results demonstrate that MTs act as a cellular “rheostat” for precisely metered insulin secretion, which is tuned by modulating MT density and dynamics.