Smad3 regulates E-cadherin via miRNA-200 pathway

Abstract

To identify potential microRNA (miRNA) links between Smad3, a mediator of TGF-b (transforming growth factor-b) signaling, and E-cadherin, we characterized the miRNA profiles of two gastric cancer cell lines: SNU484-LPCX, which does not express Smad3, and SNU484-Smad3, in which Smad3 is overexpressed. We found that among differentially expressed miRNAs, miR-200 family members are overexpressed in SNU484-Smad3 cells. Subsequent studies, including analysis of the effects of silencing Smad3 in SNU484-Smad3 cells and a luciferase reporter assay, revealed that Smad3 directly binds to a Smad-binding element located in the promoter region of miR-200b/a, where it functions as a transcriptional activator. TGF-b did not affect the regulatory role of Smad3 in transcription of miR-200 and expression of epithelial-mesenchymal transition markers. We conclude that Smad3 regulates, at the transcriptional level, miR-200 family members, which themselves regulate ZEB1 and ZEB2, known transcriptional repressors of E-cadherin, at the posttranscriptional level in a TGF-b-independent manner. This represents a novel link between Smad3 and posttranscriptional regulation by miRNAs in epithelial-mesenchymal transition in gastric cancer cells.

Upregulation of Gingival Tissue miR-200b in Obese Periodontitis Subjects

“…We further showed an inverse correlation between miR-200b-5p expression and mRNA expression of its target genes ZEB1, ZEB2, GATA2, and KDR in gingival tissue biopsies from periodontal disease patients, with ZEB2 and GATA2 being statistically significant and ZEB1 and KDR approaching a substantial trend toward significance. Previous studies have demonstrated that miRNA-200b interacts directly with the 3′ UTR of these genes and regulates their expression at the translational level (Ahn et al 2012). The above genes play central roles in pathways involved in re-epithelialization of gingival wounds (Tomikawa et al 2012), which is an important process in periodontal regeneration and reestablishment of tissue integrity, affecting treatment outcome.…”

“…The "shortlisted" miR-200b gene targets were ZEB1, ZEB2, CDH1, GATA2, PLCG1, KDR, and UBC (normalization control), as well as SMAD3, which has been reported to regulate miR-200b (Ahn et al 2012). …”

FOG2 Protein Down-regulation by Transforming Growth Factor-β1-induced MicroRNA-200b/c Leads to Akt Kinase Activation and Glomerular Mesangial Hypertrophy Related to Diabetic Nephropathy

“…Furthermore, the decreased FOG2 transcript expression in glomeruli from human subjects with DN suggests that the proposed miR-200-FOG2-Akt pathway may be significant not only in experimental animal models but also in human diabetic kidney disease as well. (47). In addition, our previous results have shown that miR-192 induced by TGF-␤ can target and down-regulate Zeb1/2 (E-box repressors) and thereby enhance the expression of miR-200b/c probably through E-boxes in their promoters (27).…”

Regulation of the MicroRNA 200b (miRNA-200b) by Transcriptional Regulators PEA3 and ELK-1 Protein Affects Expression of Pin1 Protein to Control Anoikis

“…4A and supplemental Table S1, p Ͻ 0.01), whereas Pin1 was higher in these cases (Fig. 4B and supplemental Table S1, p Ͻ 0.01) com- (30,31). We then used siRNA to knock down the expression of PEA3 and ELK-1 and found that knockdown of PEA3 decreased and knockdown of ELK-1 increased the expression of miRNA-200b (Fig.…”