Insulin signaling diverges into Akt-dependent and -independent signals to regulate the recruitment/docking and the fusion of GLUT4 vesicles to the plasma membrane. Academic Article uri icon

Overview

abstract

  • Insulin modulates glucose disposal in muscle and adipose tissue by regulating the cellular redistribution of the GLUT4 glucose transporter. Protein kinase Akt/PKB is a central mediator of insulin-regulated translocation of GLUT4; however, the GLUT4 trafficking step(s) regulated by Akt is not known. Here, we use acute pharmacological Akt inhibition to show that Akt is required for insulin-stimulated exocytosis of GLUT4 to the plasma membrane. Our data also suggest that the AS160 Rab GAP is not the only Akt target required for insulin-stimulated GLUT4 translocation. Using a total internal reflection microscopy assay, we show that Akt activity is specifically required for an insulin-mediated prefusion step involving the recruitment and/or docking of GLUT4 vesicles to within 250 nm of the plasma membrane. Moreover, the insulin-stimulated fusion of GLUT4 vesicles with the plasma membrane can occur independently of Akt activity, although based on inhibition by wortmannin, it is dependent on phosphatidylinositol 3' kinase activity. Hence, to achieve full redistribution of GLUT4 into the plasma membrane, insulin signaling bifurcates to independently regulate both fusion and a prefusion step(s).

publication date

  • August 16, 2006

Research

keywords

  • Cell Membrane
  • Glucose
  • Glucose Transporter Type 4
  • Insulin
  • Proto-Oncogene Proteins c-akt
  • Signal Transduction

Identity

PubMed Central ID

  • PMC1635362

Scopus Document Identifier

  • 33749489511

Digital Object Identifier (DOI)

  • 10.1091/mbc.e06-07-0585

PubMed ID

  • 16914513

Additional Document Info

volume

  • 17

issue

  • 10