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

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/EBPbeta, C/EBPalpha and PPARgamma, that are important for adipogenesis. Although the expression of C/EBPbeta and PPARgamma in the WAT of Fgf10(-/-) embryos was greatly decreased, the expression of C/EBPalpha was essentially unchanged. Therefore, we examined their expression in the WAT of C/EBPalpha(-/-) embryos. Although the expression of C/EBPbeta and PPARgamma in the WAY 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/EBPbeta induces the expression of PPARgamma and C/EBPalpha reported, we also examined their expression in the WAY of wild type embryos at different developmental stages. The expression of Fgf10 and C/EBPalpha was followed by that of C/EBPbeta and PPARgamma. The present findings indicate that Fgf10 but not C/EBPalpha is required for the proliferation of preadipocytes. In contrast, both Fgf10 and C/EBPalpha 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. (C) 2004 Elsevier Ireland Ltd. All rights reserved.