Objective:To investigate the effect of transforming growth factor-α(TNF-α)on adipogenesis of SD rat bone marrow mesenchymal stem cells(BMSCs)and the related molecular mechanism. Methods:The well grown third-passage(P3)SD rat BMSCs were divided into three groups:control group

Ad group and Ad+TNF-α group. RNA and proteins of the cells in three groups were collected at day 14. Cells were stained with oil red O on day 14 to examine the lipid accumulation in each group. Optical density for oil red O was determined by isopropanol extraction and was measured in a plate reader at 490 nm. The m RNA expressions of Wnt10 b

peroxisome proliferator-activated receptor-γ(PPAR-γ)

CCAAT/enhancer-binding protein-α(C/EBP-α)

fatty acid binding protein-4(FABP-4)and preadipocyte factor-1(Pref-1)were detected by q RT-PCR. The protein expression levels of P-β-catenin

PPAR-γ

C/EBP-α

FABP-4 were detected by Western blot. Results:The absorbance(A)value measured at 490 nm was significantly lower in Ad+TNF-α group(0.360±0.035)than in Ad group(0.770±0.025)(P = 0.000). q RT-PCR analysis showed that m RNA expressions of Wnt10 b and Pref-1 were significantly higher in Ad+TNF-α group(17.050±2.706

4.135±0.280)than in Ad group(0. 575 ± 0. 065

0. 514 ± 0. 060)(P = 0. 02

P = 0. 006).While the m RNA expressions of C/EBP-α

PPAR-γ and FABP-4 were significantly lower in Ad +TNF-α group(0.200 ±0.012

0.768 ±0.030

0.883 ±0.048) than in Ad group(2.965 ±0.455

2.330 ±0.211

3.847 ±0.171)(P =0.019

P =0.000

P =0.001).Western blot showed the protein expressions of C/EBP-ɑ

PPAR-γ and FABP-4 were significantly lower in Ad+TNF-α group(0.586±0.013

0.356±0.008

0.118±0.002)than in Ad group(1.082±0.018

0.840±0.112

1.094±0.038)(P=0.000). The protein expression of P-β-catenin was significantly lower in Ad+TNF-α group(0.648±0.005)than in Ad group(3.376±0.211)(P=0.000). Conclusion :The fact that TNF- α inhibits the terminal differentiation of the adipogenesis of SD rat BMSCs and blocks the adipogenesis of SD BMSCs at preadipocyte stage may relate to the increased activity of Wnt/β-catenin signaling pathway and high expression of Pref-1.