Role of the cofilin 2 gene in regulating the myosin heavy chain genes in mouse myoblast C2C12 cells.

The cofilin 2 (CFL2) and myosin heavy chain (MyHC) genes play a key role in muscle development and myofibrillar formation. The aim of the present study was to investigate the effect of CFL2 on genes involved in fiber formation and the mechanisms underlying this process. Undifferentiated and differentiated C2C12 cells (UDT and DT, respectively) were transfected with CFL2 small interfering RNA (siRNA). CFL2 mRNA and protein levels were assessed using reverse transcription polymerase chain reaction (RT-PCR) and western blotting, respectively. MyHC gene expression in UDT and signaling pathway-related factors were observed with quantitative PCR (RT‑qPCR) and western blotting. Fluorescence microscopy was used to analyze the cytoskeletal effects of CFL2. The mRNA and protein expressions of CFL2, four MyHC isoforms (MyHC-I, MyHC-IIa, MyHC-IIb and MyHC-IIx), p38 mitogen-activated protein kinase, cAMP-response element-binding protein, AMP-activated protein kinase α1, and myocyte enhancer factor 2C, were significantly decreased in UDT. However, extracellular signal-regulated kinase 2 expression was significantly increased. Slightly decreased CFL2 protein and mRNA expression was observed in DT C2C12 cells transfected with CFL2 siRNA. Fluorescence microscopy revealed a significant decrease of CFL2 in the cytoplasm, but not the nucleus, of UDT, compared with normal cells. These results indicated that the mouse CFL2 gene may be involved in the regulation of MyHC via the key signaling molecules of CFL2-related signaling pathways.