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Insulin-stimulated plasma membrane fusion of Glut4 glucose transporter-containing vesicles is regulated by phospholipase D1.

ABSTRACT: Insulin stimulates glucose uptake in fat and muscle by mobilizing Glut4 glucose transporters from intracellular membrane storage sites to the plasma membrane. This process requires the trafficking of Glut4-containing vesicles toward the cell periphery, docking at exocytic sites, and plasma membrane fusion. We show here that phospholipase D (PLD) production of the lipid phosphatidic acid (PA) is a key event in the fusion process. PLD1 is found on Glut4-containing vesicles, is activated by insulin signaling, and traffics with Glut4 to exocytic sites. Increasing PLD1 activity facilitates glucose uptake, whereas decreasing PLD1 activity is inhibitory. Diminished PA production does not substantially hinder trafficking of the vesicles or their docking at the plasma membrane, but it does impede fusion-mediated extracellular exposure of the transporter. The fusion block caused by RNA interference-mediated PLD1 deficiency is rescued by exogenous provision of a lipid that promotes fusion pore formation and expansion, suggesting that the step regulated by PA is late in the process of vesicle fusion.

SUBMITTER: Huang P

PROVIDER: S-EPMC1142410 | biostudies-literature | 2005 Jun

REPOSITORIES: biostudies-literature

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Insulin-stimulated plasma membrane fusion of Glut4 glucose transporter-containing vesicles is regulated by phospholipase D1.

Huang Ping P Altshuller Yelena M YM Hou June Chunqiu JC Pessin Jeffrey E JE Frohman Michael A MA

Molecular biology of the cell 20050316 6

Insulin stimulates glucose uptake in fat and muscle by mobilizing Glut4 glucose transporters from intracellular membrane storage sites to the plasma membrane. This process requires the trafficking of Glut4-containing vesicles toward the cell periphery, docking at exocytic sites, and plasma membrane fusion. We show here that phospholipase D (PLD) production of the lipid phosphatidic acid (PA) is a key event in the fusion process. PLD1 is found on Glut4-containing vesicles, is activated by insulin ...[more]

PMID: 15772157

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Project description:Agents that activate the G-protein G(i) (e.g. adenosine) increase, and agents that activate G(s) [e.g. isoprenaline (isoproterenol)] decrease, steady-state insulin-stimulated glucose transport activity and cell-surface GLUT4 in isolated rat adipose cells without changing plasma membrane GLUT4 content. Here we have further examined the effects of R(s)G(s) and R(i)G(i) ligands (in which R(s) and R(i) are G(s)- and G(i)-coupled receptors respectively) on insulin-stimulated cell-surface GLUT4 and the kinetics of GLUT4 trafficking in these same cells. Rat adipose cells were preincubated for 2 min with or without isoprenaline (200 nM) and adenosine deaminase (1 unit/ml), to stimulate G(s) and decrease the stimulation of G(i) respectively, followed by 0-20 min with insulin (670 nM). Treatment with isoprenaline and adenosine deaminase decreased insulin-stimulated glucose transport activity by 58%. Treatment with isoprenaline and adenosine deaminase also resulted in similar decreases in insulin-stimulated cell-surface GLUT4 as assessed by both bis-mannose photolabelling of the substrate-binding site and biotinylation of the extracellular carbohydrate moiety when evaluated under similar experimental conditions. After stimulation with insulin in the absence of G(s) and the presence of G(i) agents, a distinct sequence of plasma membrane events took place, starting with an increase in immunodetectable GLUT4, then an increase in the accessibility of GLUT4 to bis-mannose photolabel, and finally an increase in glucose transport activity. Pretreatment with isoprenaline and adenosine deaminase before stimulation with insulin did not affect the time course of the increase in immunodetectable GLUT4 in the plasma membrane, but did delay both the increase in accessibility of GLUT4 to photolabel and the increase in glucose transport activity. These results suggest that R(s)G(s) and R(i)G(i) modulate insulin-stimulated glucose transport by influencing the extent to which GLUT4 is associated with occluded vesicles attached to the plasma membrane during exocytosis, perhaps by regulating the fusion process through which the GLUT4 in docked vesicles becomes exposed on the cell surface.

Dataset Information

Insulin-stimulated plasma membrane fusion of Glut4 glucose transporter-containing vesicles is regulated by phospholipase D1.

Publications

Insulin-stimulated plasma membrane fusion of Glut4 glucose transporter-containing vesicles is regulated by phospholipase D1.

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