BAMBI Inhibits The Porcine Preadipocytes Differentiation Though Wnt/β-catenin Signaling Pathway

In recent years, obesity has become a hot issue concerned by the world. It has become athreat to human health, which likely to cause type II diabetes, cardiovascular andcerebrovascular diseases. Fat deposition is caused by the increase of adipocyte number andsize, which is the complicated process of adipocyes differentiation and maturity and regulatedby many factors. BAMBI was found recently, which can regulate adipogenesis. It is atransmembrane protein that encodes260amino acids. As its stucture is similar to type Ireceptors of TGF superfamily, it is considered to be a pseudoreceptor of TGF superfamilytype I receptor. A lot of data showed that BAMBI reguleted many physiological andpathological process in the body. In addition, BAMBI is closely related to Wnt/β-cateninsignaling during carcinogenesis. In adipogenesis, it is initially proved that BAMBI mayrepress adipocytes differentiaion, but the mechanism is unclear. Thus, in this study, wedecrease or increase the expression of BAMBI by knockdown and overexpression. Then, weused the Oil red staining, real-time quantification PCR and western blot to illuminate themechanism of BAMBI during porcine preadipocyetes differentiation. The results as follow:1. BAMBI gene is express in various tissues of3day-old piglets and180day-old pigs,the expression of BAMBI is abundant in kidney, is moderate in adipose tissue. Further, theexpression of BAMBI is higher in adipose tissue of3day-old piglets than180day-old pigsand higher in porcine preadipocyes than mature adipocytes. Finally, BAMBI is downreguletedduring porcine preadipocytes differentiation.2. The lentiviral vectors contain interference fragment of BAMBI were constructed andpackaging, then acquired high titer virus and chose the most interference-efficient interferencefragment of BAMBI (the interference effiency was above60%), named sh-BAMBI. The lipidaccumulation and the expression of adipogenic genes were increased in preadipocyetsinfected by sh-BAMBI.3. The recombinant adenovirus vector that can overexpress BAMBI was constructed andacquired high titer virus after packaging and propagated, which significantly increased BAMBI expression and named Ad-BAMBI. In the cells infected by Ad-BAMBI, the lipiddroplets and expression of adipogenic genes decreased.4. Wnt/β-catenin signaling was suppressed in BAMBI knockdown cells. Consistent withthis, BAMBI overexpression facilitated Wnt/β-catenin signaling. In the cells treated with LiCl,the expression of BAMBI increased with the increase of β-catenin expression. Moreover, theeffect of anti-adipogenic by LiCl and the nuclear translocation of β-catenin was strengthenedin BAMBI overexpression cells.The above results indicated that BAMBI inhibited porcine preadipocytes differentiation,which functioned though a positive feedback loop with Wnt/β-catenin signaling (BAMBIâ†'β-catenin nuclear translocationâ†'BAMBI). These invastigations provides a theoretical basis toimprove the carcass quality of pigs and treat obesity and its related diseases.