FIGURE 1.

Siah2 promotes adipogenesis in 3T3-L1 preadipocytes and non-precursor fibroblasts. A, 3T3-L1 preadipocytes did not undergo transfection (3T3-L1) or were stably transfected with non-silencing shRNA or Siah2 shRNA co-expressing GFP and induced to undergo adipogenesis. Accumulation of neutral lipids was detected using Oil Red O, and GFP was detected via fluorescence microscopy. B, Siah2 gene expression is up-regulated in untransfected and NS shRNA-transfected cells and specifically reduced in shSiah2-transfected cells during induction of adipogenesis. C and D, mRNA levels of transcription factors necessary for adipogenesis (C, Pparg and Cebpa) and late markers of adipogenesis (D; Adipoq, Fabp4, and Lpl) are not up-regulated in the absence of Siah2. E, neutral lipid accumulation is detected using Oil Red O in non-precursor NIH3T3 fibroblasts induced to undergo adipogenesis with or without rosiglitazone (2.5 μm, TZD) after ectopic expression of PPARγ or Siah2. F, mRNA levels of markers of adipogenesis (Pparg, Fabp4, and Lpl) are up-regulated in non-precursor fibroblasts with ectopic expression of Siah2. Gene expression was assayed using qRT-PCR. Statistical significance is compared with the corresponding day 0. *, p < 0.01.