Kinetics of contraction-induced GLUT4 translocation in skeletal muscle fibers from living mice

TY - JOUR

T1 - Kinetics of contraction-induced GLUT4 translocation in skeletal muscle fibers from living mice

AU - Lauritzen, Hans Peter M. Mortensen

AU - Galbo, Henrik

AU - Toyoda, Taro

AU - Goodyear, Laurie J

PY - 2010/9/1

Y1 - 2010/9/1

N2 - OBJECTIVE - Exercise is an important strategy for the treatment of type 2 diabetes. This is due in part to an increase in glucose transport that occurs in the working skeletal muscles. Glucose transport is regulated by GLUT4 translocation in muscle, but the molecular machinery mediating this process is poorly understood. The purpose of this study was to 1) use a novel imaging system to elucidate the kinetics of contraction-induced GLUT4 translocation in skeletal muscle and 2) determine the function of AMP-activated protein kinase α2 (AMPKα2) in this process. RESEARCH DESIGN AND METHODS - Confocal imaging was used to visualize GLUT4-enhanced green fluorescent protein (EGFP) in transfected quadriceps muscle fibers in living mice subjected to contractions or the AMPK-activator AICAR. RESULTS - Contraction increased GLUT4-EGFP translocation from intracellular vesicle depots to both the sarcolemma and t-tubules with similar kinetics, although translocation was greater with contractions elicited by higher voltage. Re-internalization of GLUT4 did not begin until 10 min after contractions ceased and was not complete until 130 min after contractions. AICAR increased GLUT4-EGFP translocation to both sarcolemma and t-tubules with similar kinetics. Ablation of AMPKα2 activity in AMPKα2 inactive transgenic mice did not change GLUT4-EGFPαs basal localization, contraction-stimulated intracellular GLUT4-EGFP vesicle depletion, translocation, or reinternalization, but diminished AICAR-induced translocation. CONCLUSIONS - We have developed a novel imaging system to study contraction-stimulated GLUT4 translocation in living mice. Contractions increase GLUT4 translocation to the sarcolemma and t-tubules with similar kinetics and do not require AMPKα2 activity.

AB - OBJECTIVE - Exercise is an important strategy for the treatment of type 2 diabetes. This is due in part to an increase in glucose transport that occurs in the working skeletal muscles. Glucose transport is regulated by GLUT4 translocation in muscle, but the molecular machinery mediating this process is poorly understood. The purpose of this study was to 1) use a novel imaging system to elucidate the kinetics of contraction-induced GLUT4 translocation in skeletal muscle and 2) determine the function of AMP-activated protein kinase α2 (AMPKα2) in this process. RESEARCH DESIGN AND METHODS - Confocal imaging was used to visualize GLUT4-enhanced green fluorescent protein (EGFP) in transfected quadriceps muscle fibers in living mice subjected to contractions or the AMPK-activator AICAR. RESULTS - Contraction increased GLUT4-EGFP translocation from intracellular vesicle depots to both the sarcolemma and t-tubules with similar kinetics, although translocation was greater with contractions elicited by higher voltage. Re-internalization of GLUT4 did not begin until 10 min after contractions ceased and was not complete until 130 min after contractions. AICAR increased GLUT4-EGFP translocation to both sarcolemma and t-tubules with similar kinetics. Ablation of AMPKα2 activity in AMPKα2 inactive transgenic mice did not change GLUT4-EGFPαs basal localization, contraction-stimulated intracellular GLUT4-EGFP vesicle depletion, translocation, or reinternalization, but diminished AICAR-induced translocation. CONCLUSIONS - We have developed a novel imaging system to study contraction-stimulated GLUT4 translocation in living mice. Contractions increase GLUT4 translocation to the sarcolemma and t-tubules with similar kinetics and do not require AMPKα2 activity.

U2 - http://dx.doi.org/10.2337/db10-0233

DO - http://dx.doi.org/10.2337/db10-0233

M3 - Journal article

SN - 0012-1797

VL - 59

SP - 2134

EP - 2144

JO - Diabetes

JF - Diabetes

IS - 9

ER -