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pubmed:abstractText |
Smad2 is an important factor in TGFbeta/Smad2 signal transduction pathway with ability for signal propagation, it could translocate from cytoplasm to nucleus after the TGFbeta receptor-mediated phosphorylation. 15-deoxy-delta(12,14)-prostaglandin J2 (15d-PGJ2), a natural agonist of the peroxisome proliferator-activated receptor gamma (PPARgamma), is found recently to be able to function in the regulation of Smad2 activity. However, no quantification data have been yet reported, and it still keeps suspenseful whether or not 15d-PGJ2 could regulate Smad2 activity by depending on PPARgamma through PPAR gamma/TGFbeta/ Smad2 pathway. In this work, by analyzing the EGFP-Smad2 location in CHO cells according to the Nucleus Trafficking Analysis Module based on IN Cell Analyzer 1000 platform, TGFbeta stimulated EGFP-Smad2 translocation regulated by 15d-PGJ2 was quantitatively investigated. The results showed that TGFbeta could induce EGFP-Smad2 translocation from cytoplasm to nucleus by EC50 of 8.83 pM, and 15d-PGJ2 could impede the TGFbeta-stimulated Smad2 translocation by IC50 of 0.68 microM. Moreover, GW9662, a PPARgamma antagonist, could attenuate such a 15d-PGJ2 inhibitory activity by almost one order of magnitude. This result thereby implies that 15d-PGJ2 might inhibit Smad2 translocation through PPARgamma/TGFbeta/Smad2 pathway. Further investigation discovered that different from the case for 15d-PGJ2, rosiglitazone, another PPARgamma agonist, could enhance Smad2 translocation to nucleus, suggesting that rosiglitazone and 15d-PGJ(2) might take different modes in the activation of PPARgamma within the signaling pathway.
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