Abstract
Skeletal myogenesis is required to maintain muscle mass and integrity, and impaired myogenesis is causally linked to the etiology of muscle wasting. Recently, it was shown that excessive uptake of saturated fatty acids (SFA) plays a significant role in the pathogenesis of muscle wasting. Although microRNA (miRNA) is implicated in the regulation of myogenesis, the molecular mechanism whereby SFA-induced miRNAs impair myogenic differentiation remains largely unknown. Here, we investigated the regulatory roles of miR-325-3p on CFL2 expression and myogenic differentiation in C2C12 myoblasts. PA impeded myogenic differentiation, concomitantly suppressed CFL2 and induced miR-325-3p. Dual-luciferase analysis revealed that miR-325-3p directly targets the 3′UTR of CFL2, thereby suppressing the expression of CFL2, a crucial factor for actin dynamics. Transfection with miR-325-3p mimic resulted in the accumulation of actin filaments (F-actin) and nuclear Yes-associated protein (YAP) in myoblasts and promoted myoblast proliferation and cell cycle progression. Consequently, miR-325-3p mimic significantly attenuated the expressions of myogenic factors and thereby impaired the myogenic differentiation of myoblasts. The roles of miR-325-3p on CFL2 expression, F-actin modulation, and myogenic differentiation suggest a novel miRNA-mediated regulatory mechanism of myogenesis and PA-inducible miR-325-3p may be a critical mediator between obesity and muscle wasting.
Highlights
Skeletal muscle is essential for proper physical and systemic homeostasis, including locomotion, metabolism, and respiration [1]
Since Cofilin 2 (CFL2) is necessary for myoblast differentiation [25], we investigated how CFL2 expression during differentiation is affected by saturated fatty acids (SFA) in myoblasts
These results suggest that impaired myogenic differentiation by palmitic acid (PA) is associated with CFL2 suppression in myoblasts
Summary
Skeletal muscle is essential for proper physical and systemic homeostasis, including locomotion, metabolism, and respiration [1]. Dysregulation of myogenesis induces muscle wasting diseases, including sarcopenia and cachexia, and increases the risks of frailty, morbidity, and mortality [2,3]. Numerous studies have indicated that muscle wasting is derived from diverse conditions that impede myogenesis, such as oxidative stress, mitochondrial dysfunction, and senescence [3,4]. Excess uptake of saturated fatty acids (SFA) increases intramuscular fat infiltration and frequently provokes muscle wasting [7,8]. Many studies have shown that certain microRNAs (miRNAs) dysregulated by SFA, and obesity are associated with muscle wasting [9,10]
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