Abstract
Actin dynamics are known to orchestrate various myogenic processes in progenitor cells. Twinfilin-1 (TWF1) is an actin-depolymerizing factor that plays a crucial role in the differentiation of myogenic progenitor cells. However, little is known about the mechanisms underlying the epigenetic regulation of TWF1 expression and impaired myogenic differentiation in the background of muscle wasting. This study investigated how miR-665-3p affects TWF1 expression, actin filaments' modulation, proliferation, and myogenic differentiation in progenitor cells. Palmitic acid, the most prevalent saturated fatty acid (SFA) in food, suppressed TWF1 expression and inhibited the myogenic differentiation of C2C12 cells while increasing the level of miR-665-3p expression. Interestingly, miR-665-3p inhibited TWF1 expression by targeting TWF1 3'UTR directly. In addition, miR-665-3p accumulated filamentous actin (F-actin) and enhanced the nuclear translocation of Yes-associated protein 1 (YAP1), consequently promoting cell cycle progression and proliferation. Furthermore, miR-665-3p suppressed the expressions of myogenic factors, i.e., MyoD, MyoG, and MyHC, and consequently impaired myoblast differentiation. In conclusion, this study suggests that SFA-inducible miR-665-3p suppresses TWF1 expression epigenetically and inhibits myogenic differentiation by facilitating myoblast proliferation via the F-actin/YAP1 axis.