Roles of fibroblast growth factor 10 (Fgf10) in adipogenesis in vivo.

Abstract The development of white adipose tissue (WAT) of Fgf10 −/− mouse embryos was greatly impaired. Here, we examined the mechanism of Fgf10 action in adipogenesis in vivo. The proliferative activity in the WAT of Fgf10 −/− embryos was greatly decreased. We also examined the expression of transcription factors, C / EBP β, C / EBP α and PPAR γ, that are important for adipogenesis. Although the expression of C / EBP β and PPAR γ in the WAT of Fgf10 −/− embryos was greatly decreased, the expression of C / EBP α was essentially unchanged. Therefore, we examined their expression in the WAT of C / EBP α −/− embryos. Although the expression of C / EBP β and PPAR γ in the WAT was greatly decreased, the expression of Fgf10 was essentially unchanged. As these results in vivo appeared to be contradictory to a transcriptional cascade model in vitro that C / EBP β induces the expression of PPAR γ and C / EBP α reported, we also examined their expression in the WAT of wild type embryos at different developmental stages. The expression of Fgf10 and C / EBP α was followed by that of C / EBP β and PPAR γ. The present findings indicate that Fgf10 but not C / EBP α is required for the proliferation of preadipocytes. In contrast, both Fgf10 and C / EBP α acting synergistically in separate, parallel pathways are required for the differentiation. Unexpectedly, the transcriptional cascade of adipogenesis in vivo described here is distinct from the cascade in vitro previously reported.