Exercise induces a transient increase in transcription of the GLUT-4 gene in skeletal muscle

Am J Physiol. 1993 Dec;265(6 Pt 1):C1597-603. doi: 10.1152/ajpcell.1993.265.6.C1597.

Abstract

Endurance exercise training elicits an increase in mitochondrial density as well as GLUT-4 glucose transporter protein content in skeletal muscle. Corresponding increases in mRNA for respiratory enzymes and GLUT-4 indicate that pretranslational control mechanisms are involved in this adaptive process. To directly test whether transcription of the GLUT-4 gene is activated in response to exercise training, nuclei were isolated from red hindlimb skeletal muscle of rats after 1 wk of exercise training (8% grade, 32 m/min, 40 min, twice/day). Rats were killed either 30 min, 3 h, or 24 h after the last training session. GLUT-4 transcription, determined by nuclear run-on analysis, was unaltered after 30 min, increased by 1.8-fold after 3 h, but was no longer different from controls 24 h after exercise. A similar transient increase in GLUT-4 transcription was evident, but less pronounced (1.4-fold), in untrained rats after a single bout of exercise, suggesting that the postexercise induction in GLUT-4 gene transcription is enhanced by exercise training. GLUT-4 protein content was increased 1.7-fold after 1 wk of training in the absence of any corresponding change in GLUT-4 mRNA, providing evidence that the initial increase in GLUT-4 expression involves translational and/or posttranslational control mechanisms. These findings demonstrate that muscle GLUT-4 expression in response to exercise training is subject to both transcriptional and posttranscriptional regulation. We propose that the increase in GLUT-4 mRNA evident with extended periods of training may result from a shift to pretranslational control and is the cumulative effect of repeated postexercise transient increases in GLUT-4 gene transcription.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Analysis of Variance
  • Animals
  • Blotting, Northern
  • Blotting, Western
  • Cell Nucleus / metabolism
  • Citrate (si)-Synthase / metabolism
  • Gene Expression Regulation / physiology*
  • Glucose Transporter Type 1
  • Glucose Transporter Type 4
  • Male
  • Molecular Weight
  • Monosaccharide Transport Proteins / biosynthesis*
  • Monosaccharide Transport Proteins / isolation & purification
  • Monosaccharide Transport Proteins / metabolism
  • Muscle Proteins*
  • Muscles / metabolism
  • Muscles / physiology*
  • Physical Conditioning, Animal*
  • RNA / isolation & purification
  • Rats
  • Rats, Sprague-Dawley
  • Time Factors
  • Transcription, Genetic*

Substances

  • Glucose Transporter Type 1
  • Glucose Transporter Type 4
  • Monosaccharide Transport Proteins
  • Muscle Proteins
  • Slc2a4 protein, rat
  • RNA
  • Citrate (si)-Synthase