Related Experiment Video

Updated: Aug 7, 2026

Measurement of Insulin- and Contraction-Stimulated Glucose Uptake in Isolated and Incubated Mature Skeletal Muscle from Mice
08:01

Measurement of Insulin- and Contraction-Stimulated Glucose Uptake in Isolated and Incubated Mature Skeletal Muscle from Mice

Published on: May 16, 2021

Distinct signals regulate AS160 phosphorylation in response to insulin, AICAR, and contraction in mouse skeletal

Henning F Kramer1, Carol A Witczak, Nobuharu Fujii

  • 1Section Head, Metabolism, Joslin Diabetes Center, One Joslin Pl., Boston, MA 02215, USA.

Diabetes
|June 29, 2006
PubMed

Insights

Insulin and muscle contraction stimulate glucose uptake via distinct pathways. Both pathways converge on AS160 phosphorylation, involving Akt and AMPK signaling, but contraction

Area of Science:

  • * Molecular biology
  • * Cell signaling
  • * Exercise physiology

Background:

  • * Glucose transporter type 4 (GLUT4) translocation to the plasma membrane is crucial for glucose uptake in skeletal muscle.
  • * Insulin and muscle contraction are major stimulators of GLUT4 translocation, but their signaling pathways differ.
  • * Akt substrate of 160 kDa (AS160) is a key regulator in insulin-stimulated GLUT4 trafficking.

Purpose of the Study:

  • * To investigate the distinct and convergent signaling mechanisms regulating AS160 phosphorylation by insulin, contraction, and AICAR (an AMPK activator).
  • * To elucidate the roles of Akt and AMP-activated protein kinase (AMPK) in mediating these responses in mouse skeletal muscle.

Main Methods:

  • * In vivo, in vitro, and in situ experiments using wild-type, Akt2 knockout, and AMPK alpha2-inactive transgenic mice.
  • * Treatment with wortmannin (an Akt inhibitor) and AICAR (an AMPK activator).
  • * Measurement of AS160 phosphorylation levels under various stimulation conditions.

Main Results:

  • * Insulin-stimulated AS160 phosphorylation is dependent on Akt2 and inhibited by wortmannin.
  • * Contraction-stimulated AS160 phosphorylation is only partially affected by wortmannin and Akt2 knockout, suggesting alternative pathways.
  • * AICAR-stimulated AS160 phosphorylation is mediated by AMPK alpha2, while contraction-stimulated phosphorylation involves both Akt and AMPK alpha2, with neither being solely indispensable.

Conclusions:

  • * AS160 serves as a convergence point for insulin, contraction, and AICAR signaling pathways in skeletal muscle.
  • * Akt and AMPK alpha2 are essential for insulin and AICAR-induced AS160 phosphorylation, respectively.
  • * Contraction-induced AS160 phosphorylation involves complex regulation by both Akt and AMPK, with neither kinase fully accounting for the effect.

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