Muscle Type-Specific Modulation of Autophagy Signaling in Obesity: Effects of Caloric Restriction and Exercise

Area of Science:

• Metabolic Health
• Cellular Biology
• Exercise Physiology

Background:

• Obesity induces metabolic dysregulation, impacting diseases.
• Autophagy, a cellular recycling process, is crucial in metabolic health.
• Skeletal muscle autophagy regulation during obesity and interventions is not well understood.

Purpose of the Study:

• To investigate the effects of caloric restriction (CR) and CR with exercise (CR+Ex) on autophagy in skeletal muscle of obese mice.
• To compare autophagy markers between red and white muscle under different dietary and exercise conditions.

Main Methods:

• Mice were assigned to normal or high-fat diets, followed by CR or CR+Ex interventions.
• Body composition, motor function, and autophagy signaling markers (p62, LC3B-I, LC3B-II, cathepsin L) were assessed.
• Muscle tissue was analyzed for differences between red and white muscle.

Main Results:

• Obesity increased body mass and fat percentage while decreasing motor function.
• CR+Ex significantly reduced body mass, lean mass, and fat mass in obese mice.
• Autophagy markers were higher in red muscle; obesity reduced cathepsin L, while CR increased LC3B-I in red muscle.

Conclusions:

• CR+Ex is an effective strategy to reverse obesity-related body composition changes.
• White muscle has lower autophagy protein levels and may benefit from increased cathepsin L to counteract obesity's effects.
• Understanding muscle-specific autophagy regulation is key for metabolic health interventions.