肌动蛋白细胞骨架的动态重排在肌生成中起着至关重要的作用。它受到不同机制的监管,比如机械传导,调节Hippo信号通路,控制细胞增殖,以及形态变化的影响。尽管肌动蛋白结合蛋白Flightless-1(FLII)在肌动蛋白重塑过程中具有公认的重要性,FLII在生肌祖细胞分化中的作用尚未被研究。这里,我们研究了FLII在成肌细胞增殖和分化中的作用。发现FLII富含C2C12成肌细胞,并且其表达在分化的早期阶段稳定,但在完全分化的肌管中下调。C2C12成肌细胞中FLII的敲除导致丝状肌动蛋白(F-肌动蛋白)积累并抑制Yes相关蛋白1(YAP1)磷酸化,从而触发它从细胞质中的核易位。因此,YAP1靶基因的表达,包括PCNA,CCNB1和CCND1被诱导,促进成肌细胞的细胞周期和增殖。此外,FLII基因敲低显著抑制生肌调节因子的表达,即,MyoD和MyoG,从而损害成肌细胞分化,聚变,和肌管的形成。因此,我们的研究结果表明,FLII通过调节F-肌动蛋白/YAP1轴对成肌细胞的分化至关重要,并提示FLII是肌肉萎缩的一种新的治疗靶点.
The dynamic rearrangement of the actin cytoskeleton plays an essential role in myogenesis, which is regulated by diverse mechanisms, such as mechanotransduction, modulation of the Hippo signaling pathway, control of cell proliferation, and the influence of morphological changes. Despite the recognized importance of actin-binding protein Flightless-1 (
FLII) during actin remodeling, the role played by
FLII in the differentiation of myogenic progenitor cells has not been explored. Here, we investigated the roles of
FLII in the proliferation and differentiation of myoblasts.
FLII was found to be enriched in C2C12 myoblasts, and its expression was stable during the early stages of differentiation but down-regulated in fully differentiated myotubes. Knockdown of FLII in C2C12 myoblasts resulted in filamentous actin (F-actin) accumulation and inhibited Yes-associated protein 1 (YAP1) phosphorylation, which triggers its nuclear translocation from the cytoplasm. Consequently, the expressions of YAP1 target genes, including PCNA, CCNB1, and CCND1, were induced, and the cell cycle and proliferation of myoblasts were promoted. Moreover,
FLII knockdown significantly inhibited the expression of myogenic regulatory factors, i.e., MyoD and MyoG, thereby impairing myoblast differentiation, fusion, and myotube formation. Thus, our findings demonstrate that FLII is crucial for the differentiation of myoblasts via modulation of the F-actin/YAP1 axis and suggest that FLII is a putative novel therapeutic target for muscle wasting.