Background: Adipogenesis and fibrogenesis can be considered as a competitive process in muscle, which may affect the intramuscular fat deposition. The CCAAT/enhancer-binding protein beta (C/EBPβ) plays an important role in adipogenesis, which is well-characterized in mice, but little known in bovine so far.

Results: In this study, real-time qPCR revealed that the level of C/EBPβ was increased during the developmental stages of bovine and adipogenesis process of preadipocytes. Overexpression of C/EBPβ promoted bovine fibroblast proliferation through mitotic clonal expansion (MCE), a necessary process for initiating adipogenesis, by significantly downregulating levels of p21 and p27 (p < 0.01). Also, the PPARγ expression was inhibited during the MCE stage (p < 0.01). 31.28% of transfected fibroblasts adopted lipid-laden adipocyte morphology after 8 d. Real-time qPCR showed that C/EBPβ activated the transcription of early stage adipogenesis markers C/EBPα and PPARγ. Expression of ACCα, FASN, FABP4 and LPL was also significantly upregulated, while the expression of LEPR was weakened.

Conclusions: It was concluded C/EBPβ can convert bovine fibroblasts into adipocytes without hormone induction by initiating the MCE process and promoting adipogenic genes expression, which may provide new insights into the potential functions of C/EBPβ in regulating intramuscular fat deposition in beef cattle.