Relationship between insulin sensitivity and gene expression in human skeletal muscle

Area of Science:

• Molecular Biology
• Metabolic Research
• Genetics

Background:

• Insulin resistance (IR) in skeletal muscle is a critical factor in pre-diabetes, hypertension, dyslipidemia, and cardiovascular diseases.
• It also predicts the onset of type 2 diabetes, but the molecular underpinnings remain unclear.

Purpose of the Study:

• To investigate the molecular mechanisms of insulin resistance in skeletal muscle.
• To identify genes correlated with insulin sensitivity in human skeletal muscle.

Main Methods:

• Global skeletal muscle gene expression profiling was performed on 38 non-diabetic men.
• Gene expression data were correlated with the homeostatic model assessment of insulin resistance (HOMA-IR) as a measure of insulin sensitivity.

Main Results:

• 180 genes showed significant correlation with insulin sensitivity in skeletal muscle.
• Autophagy-related genes, SIRT2 (lipid metabolism), and FBXW5 (mTOR and autophagy regulation) were positively correlated with insulin sensitivity.
• Expression of SIRT2 and FBXW5 correlated with genes promoting an insulin-sensitive myocyte phenotype, such as PPARGC1A.

Conclusions:

• Skeletal muscle gene expression of 180 genes is linked to insulin sensitivity.
• Activation of lipid metabolism genes (e.g., SIRT2) and autophagy/mTOR signaling genes (e.g., FBXW5) is associated with enhanced insulin sensitivity.
• These findings suggest a role for flexible nutrient sensing in maintaining insulin sensitivity in human skeletal muscle.