TY - JOUR
T1 - Glucose-stimulated insulin secretion is coupled to the interaction of actin with the t-SNARE (target membrane soluble N-ethylmaleimide-sensitive factor attachment protein receptor protein) complex
AU - Thurmond, Debbie C.
AU - Gonelle-Gispert, Carmen
AU - Furukawa, Megumi
AU - Halban, Philippe A.
AU - Pessin, Jeffrey E.
PY - 2003/4/1
Y1 - 2003/4/1
N2 - The actin monomer sequestering agent latrunculin B depolymerized β-cell cortical actin, which resulted in increased glucose-stimulated insulin secretion in both cultured MIN6 β-cells and isolated rat islet cells. In perifused islets, latrunculin B treatment increased both first- and second-phase glucose-stimulated insulin secretion without any significant effect on total insulin content. This increase in secretion was independent of calcium regulation because latrunculin B also potentiated calcium-stimulated insulin secretion in permeabilized MIN6 cells. Confocal immunofluorescent microscopy revealed a redistribution of insulin granules to the cell periphery in response to glucose or latrunculin B, which correlated with a reduction in phalloidin staining of cortical actin. Moreover, the t-SNARE [target membrane soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptor] proteins Syntaxin 1 and SNAP-25 coimmunoprecipitated polymerized actin from unstimulated MIN6 cells. Glucose stimulation transiently decreased the amount of actin coimmunoprecipitated with Syntaxin 1 and SNAP-25, and latrunculin B treatment fully ablated the coimmunoprecipitation. In contrast, the actin stabilizing agent jasplakinolide increased the amount of actin coimmunoprecipitated with the t-SNARE complex and prevented its dissociation upon glucose stimulation. These data suggest a mechanism whereby glucose modulates β-cell cortical actin organization and disrupts the interaction of polymerized actin with the plasma membrane t-SNARE complex at a distal regulatory step in the exocytosis of insulin granules.
AB - The actin monomer sequestering agent latrunculin B depolymerized β-cell cortical actin, which resulted in increased glucose-stimulated insulin secretion in both cultured MIN6 β-cells and isolated rat islet cells. In perifused islets, latrunculin B treatment increased both first- and second-phase glucose-stimulated insulin secretion without any significant effect on total insulin content. This increase in secretion was independent of calcium regulation because latrunculin B also potentiated calcium-stimulated insulin secretion in permeabilized MIN6 cells. Confocal immunofluorescent microscopy revealed a redistribution of insulin granules to the cell periphery in response to glucose or latrunculin B, which correlated with a reduction in phalloidin staining of cortical actin. Moreover, the t-SNARE [target membrane soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptor] proteins Syntaxin 1 and SNAP-25 coimmunoprecipitated polymerized actin from unstimulated MIN6 cells. Glucose stimulation transiently decreased the amount of actin coimmunoprecipitated with Syntaxin 1 and SNAP-25, and latrunculin B treatment fully ablated the coimmunoprecipitation. In contrast, the actin stabilizing agent jasplakinolide increased the amount of actin coimmunoprecipitated with the t-SNARE complex and prevented its dissociation upon glucose stimulation. These data suggest a mechanism whereby glucose modulates β-cell cortical actin organization and disrupts the interaction of polymerized actin with the plasma membrane t-SNARE complex at a distal regulatory step in the exocytosis of insulin granules.
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U2 - 10.1210/me.2002-0333
DO - 10.1210/me.2002-0333
M3 - Article
C2 - 12554769
AN - SCOPUS:0037384072
SN - 0888-8809
VL - 17
SP - 732
EP - 742
JO - Molecular Endocrinology
JF - Molecular Endocrinology
IS - 4
ER -