Endurance training-induced changes in insulin sensitivity and gene expression

Area of Science:

• Exercise physiology
• Molecular biology
• Genetics

Background:

• Regular physical activity enhances insulin sensitivity (SI) and glucose tolerance.
• Individual responses to exercise training (ET) for SI improvement exhibit significant variability.
• Understanding the genetic basis of this variability is crucial for personalized exercise prescriptions.

Purpose of the Study:

• To identify novel candidate genes associated with exercise training-induced improvements in insulin sensitivity.
• To compare gene expression profiles between individuals with high and low responsiveness to exercise training.
• To elucidate the molecular mechanisms underlying enhanced insulin sensitivity post-exercise.

Main Methods:

• Microarray analysis of vastus lateralis muscle RNA from 16 participants (8 high responders, 8 low responders) before and after 20 weeks of ET.
• Insulin sensitivity index (SI) derived from frequently sampled intravenous glucose tolerance tests.
• Gene expression data validated using quantitative RT-PCR.

Main Results:

• Significant differences in gene expression between high and low responders were more pronounced after training than before.
• Identified differentially expressed genes involved in energy metabolism, signaling, and novel structural components.
• Upregulated genes in high responders included V-Ski oncogene, four-and-a-half LIM domain 1, and titin.

Conclusions:

• Exercise training significantly alters muscle gene expression, with distinct patterns observed between individuals who show marked improvements in insulin sensitivity and those who do not.
• Novel candidate genes, including V-Ski oncogene, four-and-a-half LIM domain 1, and titin, are implicated in exercise-induced improvements in insulin sensitivity.
• Further investigation of these genes may enhance our understanding of the molecular basis of insulin sensitivity regulation by exercise.