Overexpression of CPT1A disrupts the maintenance and regenerative function of muscle stem cells

Area of Science:

• Muscle biology
• Cellular metabolism
• Regenerative medicine

Background:

• Skeletal muscle satellite cells (SCs) are crucial for muscle repair and regeneration.
• Metabolic shifts, particularly in fatty acid oxidation (FAO), occur as SCs transition from quiescence to activation.
• Carnitine palmitoyltransferase 1A (CPT1A) is the rate-limiting enzyme in mitochondrial FAO.

Purpose of the Study:

• To investigate the role of CPT1A and mitochondrial FAO in SC function and myogenesis.
• To determine how altered CPT1A expression impacts SC maintenance, proliferation, and regenerative capacity.

Main Methods:

• Examined CPT1A expression in quiescent, activated, and differentiating SCs.
• Utilized Myod1Cre-driven and Pax7CreER-driven Cpt1a overexpression (OE) models in mice.
• Assessed muscle weight, strength, endurance, SC number, and lipid infiltration.
• Measured acyl-carnitine levels and their effect on SC proliferation.

Main Results:

• CPT1A expression is higher in quiescent SCs and decreases during differentiation.
• Cpt1a OE in myoblasts and adult SCs reduced muscle function, SC number, and impaired regeneration.
• Elevated acyl-carnitine levels were observed in Cpt1a OE SCs, and exogenous acyl-carnitine inhibited SC proliferation.

Conclusions:

• Aberrant CPT1A levels disrupt SC homeostasis by increasing acyl-carnitine.
• Elevated acyl-carnitine impairs SC maintenance, proliferation, and regenerative potential.
• CPT1A-mediated FAO is critical for proper SC function and muscle regeneration.