Hsa-miR-590-5p Interaction with SMAD3 Transcript Supports Its Regulatory Effect on the TGFβ Signaling Pathway

Objective: smad proteins are the core players of the transforming growth factor-beta (tgfβ) signaling pathway, a pathway which is involved in cell proliferation, differentiation and migration. on the other hand, hsa-mirna-590-5p (mir-590-5p) is known to have a negative regulatory effect on tgfβ signaling pathway receptors. since, rnahybrid analysis suggested smad3 as a bona fide target gene for mir-590, we intended to investigate the effect of mir-590-5p on smad3 transcription. materials and methods: in this experimental study, mir-590-5p was overexpressed in different cell lines and its increased expression was detected through quantitative reverse transcription-polymerase chain reaction (rt-qpcr). western blot analysis was then used to investigate the effect of mir-590-5p overexpression on smad3 protein level. next, the direct interaction of mir-590-5p with the 3´-utr sequence of smad3 transcript was investigated using the dual luciferase assay. finally, flow cytometery was used to investigate the effect of mir-590-5p overexpression on cell cycle progression in hela and sw480 cell lines. results: mir-590-5p was overexpressed in the sw480 cell line and its overexpression resulted in significant reduction of the smad3 protein level. consistently, direct interaction of mir-590-5p with 3´-utr sequence of smad3 was detected. finally, mir-590-5p overexpression did not show a significant effect on cell cycle progression of hela and sw480 cell lines. conclusion: consistent with previous reports about the negative regulatory effect of mir-590 on tgfβ receptors, our data suggest that mir-590-5p also attenuates the tgfβ signaling pathway through down-regulation of smad3.