Mu-Crystallin in Mouse Skeletal Muscle Promotes a Shift from Glycolytic Toward Oxidative Metabolism

The study investigated the effects of overexpressing μ-crystallin in mouse skeletal muscle, revealing that it promoted a shift from glycolytic to oxidative metabolism. Transgenic mice with elevated Crym protein levels showed a significant decrease in the respiratory exchange ratio, indicating a 13.7% increase in fat utilization as an energy source. Despite elevated T3 levels in muscle and decreased serum T4, muscular functions remained largely unchanged. Female transgenic mice gained weight more rapidly on high-fat or high-carbohydrate diets. RNA-seq and protein expression analyses indicated a shift towards genes and proteins associated with slower muscle function and β-oxidation. The findings suggested that μ-crystallin played a crucial role in substrate utilization, favoring fat metabolism in mammalian muscle.