Effects Of PPARγ Agonist On Metabolism Of Smad2/3Pathway In Osteoblasts

Objective Through investigating the effect of PPARγ agonist pioglitazone on theexpression of Smad2/3protein and mRNA in cultured osteoblasts induced by TGF-β1,understand the regulatory mechanism of PPARγ on metabolism and study the possibleeffects of PPARγ agonist in the process of osteoporosis.Methods Osteoblasts were obtained from new born24hours rat calvaria by digestiveenzyme. After the alizarin red calcium nodules dyeing and alkaline phosphatase stainingidentified as osteoblasts. MTT and AKP detection were separatelly used to observe theproliferation and activity of AKP of cultured osteoblasts stimulated by pioglitazone in vitro.The expression of Smad2/3and P-Smad3protein and mRNA were respectively measuredby immunofluoresence, western blot and Real-time PCR analysis.Results Pioglitazone had no effect on stimulating cell proliferation (P>0.05), butinhibited the activity of AKP in osteoblasts (P<0.05). Treatment with5ng/ml TGF-β1for24h inhibited Smad2/3and P-Smad3protein and mRNA levels in osteoblasts, the mRNAexpression of Smad2and Smad3declined with the increase of concentration of PPARγagonist (P<0.05).Conclusion PPARγ agonist could inhibit the differentiation of osteoblasts, and couldeffectively participate in the process of osteoporosis and just possibly by inhibitingTGF-β1-induced expression of Smad2/3and P-Smad3in the cultured osteoblasts.