Characterization of chicken <I>PPARγ</I> expression and its impact on adipocyte proliferation and differentiation

Abstract

To characterize the chicken PPARγ gene expression and its impact on chicken adipocyte proliferation and differentiation, western blotting approach was conducted to investigate the expression of PPARγ in various chicken tissues and the difference of expression level in abdominal adipose tissues between the NEAU broiler lines divergently selected for abdominal fat content. The expression of PPARγ gene was suppressed in chicken adipocytes using RNAi technology, and the roles of PPARγ gene in the adipocytes proliferation and differentiation were investigated by MTT assay and Oil Red O staining extraction assay, respectively. After PPARγ gene was downregulated, the expression level of other transcript factors and marker genes related to the adipocyte differentiation was detected by Real-time PCR and Western blotting analyses. The results showed that PPARγ highly expressed in abdominal adipose tissue, gizzard, spleen, kidney, lowly expressed in heart, and not expressed in liver, breast muscle, leg muscle, and duodenum. Meanwhile, PPARγ expressed much higher in fat birds than in lean ones in abdominal adipose tissue at 5 and 7 weeks of age (P<0.05). RNAi analysis showed that knockdown of PPARγ gene increased chicken adipocyte proliferation and decreased cell differentiation and significantly decreased the expression levels of C/EBPα, SREBP1, A-FABP, Perilipin1, LPL, and IGFBP-2 (P<0.05). In summary, PPARγ gene may be related to the broiler abdominal fat deposition, and be probably a key regulator of chicken adipocyte proliferation and differentiation.