PT - JOURNAL ARTICLE AU - Takehiko Ueyama AU - Megumi Sakuma AU - Mio Nakatsuji AU - Tatsuya Uebi AU - Takeshi Hamada AU - Atsu Aiba AU - Naoaki Saito TI - Rac-dependent signaling from keratinocytes promotes differentiation of intradermal white adipocytes AID - 10.1101/474056 DP - 2018 Jan 01 TA - bioRxiv PG - 474056 4099 - http://biorxiv.org/content/early/2018/11/19/474056.short 4100 - http://biorxiv.org/content/early/2018/11/19/474056.full AB - Rac signaling affects numerous downstream targets; however, few studies have established in vivo levels. We generated mice with a single knockout (KO) of Rac1 (Keratin5 (K5)-Cre;Rac1flox/flox, Rac1-KO) and double KO of Rac1 and Rac3 (K5-Cre;Rac1flox/flox;Rac3−/−, Rac1/Rac3-DKO) in keratinocytes. Strikingly, Rac1-KO mice exhibited thinner dermal white adipose tissue, which was considerably further reduced in Rac1/Rac3-DKO mice. DNA microarray using primary keratinocytes from Rac1/Rac3-DKO mice exhibited decreased mRNA levels of Bmp2, Bmp5, Fgf20, Fgf21, Fgfbp1, and Pdgfα. Combinational treatment with BMP2 and FGF21 or BMP2 and FGF20 in culture medium, but not individual purified recombinant proteins, could differentiate 3T3-L1 fibroblasts into adipocytes, as could culture media obtained from primary keratinocytes. Conversely, addition of anti-BMP2 or anti-FGF21 antibodies into the culture medium inhibited fibroblast differentiation. Furthermore, combinational treatment with BMP2 and FGF21 promoted adipocyte differentiation only of rat primary white, but not brown, adipocyte precursors. Notably, brown adipogenesis by FGF21 was inhibited by BMP2. Thus, we proposed novel paracrine pathways from keratinocytes to intradermal pre-adipocytes, which function as Rac-dependent modulators of white adipogenesis, but also brown adipogenesis.