Cold Stress Regulates Muscle Development and Promotes Muscle Fiber Transformation by Regulating Mib1/Notch Pathway.

Background: In mammals, skeletal muscle typically constitutes approximately 55% of body weight. The thermogenesis of skeletal muscle increases with increased cold stress, and skeletal muscle maintains the animal's body temperature through the heat generated by shivering. However, less attention has been paid to investigating the impact of cold stress on the fiber type makeup of skeletal muscle, especially the gastrocnemius. Consequently, this research explored how cold stress regulates muscle development and fiber type composition.

Methods: A cold stress model was established by subjecting mice to a 4 °C environment for 4 hours daily. This model was combined with an in vitro siRNA-mediated knockdown model for joint validation. The impact of cold stress on skeletal muscle development and myofiber type transformation was assessed using experimental techniques, including immunofluorescence and western blotting.

Results: Following cold stress, the expression level of Myosin Heavy Chain 7 (MYH7) in the mouse gastrocnemius increased, while Myosin Heavy Chain 4 (MYH4) expression decreased. Concurrently, elevated expressions of Mindbomb-1 (Mib1) and the myogenic differentiation (MyoD) were observed. Subsequent knockdown of Mib1 in C2C12 cells resulted in increased MYH4 expression and decreased MYH7 expression.

Conclusion: Cold stress induces skeletal muscle fibers to shift from fast-twitch to slow-twitch through the Mib1/Notch signaling pathway.