Microtubules Negatively Regulate Insulin Secretion in Pancreatic β Cells

Dev Cell. 2015 Sep 28;34(6):656-68. doi: 10.1016/j.devcel.2015.08.020.


For glucose-stimulated insulin secretion (GSIS), insulin granules have to be localized close to the plasma membrane. The role of microtubule-dependent transport in granule positioning and GSIS has been debated. Here, we report that microtubules, counterintuitively, restrict granule availability for secretion. In β cells, microtubules originate at the Golgi and form a dense non-radial meshwork. Non-directional transport along these microtubules limits granule dwelling at the cell periphery, restricting granule availability for secretion. High glucose destabilizes microtubules, decreasing their density; such local microtubule depolymerization is necessary for GSIS, likely because granule withdrawal from the cell periphery becomes inefficient. Consistently, microtubule depolymerization by nocodazole blocks granule withdrawal, increases their concentration at exocytic sites, and dramatically enhances GSIS in vitro and in mice. Furthermore, glucose-driven MT destabilization is balanced by new microtubule formation, which likely prevents over-secretion. Importantly, microtubule density is greater in dysfunctional β cells of diabetic mice.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Cells, Cultured
  • Cytoplasmic Granules / drug effects
  • Cytoplasmic Granules / metabolism
  • Diabetes Mellitus, Experimental / physiopathology*
  • Diabetes Mellitus, Type 2 / physiopathology*
  • Female
  • Glucose / pharmacology*
  • Insulin / metabolism*
  • Insulin Secretion
  • Insulin-Secreting Cells / drug effects
  • Insulin-Secreting Cells / metabolism*
  • Mice
  • Microtubules / physiology*
  • Sweetening Agents / pharmacology


  • Insulin
  • Sweetening Agents
  • Glucose