Regulatory mechanisms of miRNA-126 expression in ulcerative colitis

Abstract

Abstract Background and Objective :Our previous studies found that miR-126 was significantly upregulated in ulcerative colitis and promoted inflammatory responses by activating the NF-κB signalling pathway. This study aimed to explore the transcriptional mechanisms involved in miR-126 upregulation. Methods: miRNAs and mRNAs expression were measured by qRT-PCR. Proteins amounts were measured by Western Blot. The core promoter sequences of miR-126 and its host gene EGFL7 were determined via the luciferase reporter system. Binding of NF-κB3 to the core promoter region of miR-126 was detected by an electrophoretic mobility shift assay (EMSA). Results: In the HT-29 cell line, stimulation of TNFa, IL-1β, LPS, MDP, HKM, and ODN2006 led to a discordant expression pattern of miR-126 and EGFL7, while IFN-γ or FLA-ST treatment resulted in a concordant expression pattern of miR-126 and EGFL7. Luciferase activity analysis revealed that miR-126 has its own independent promoter. NF-κB3 could directly bind to the core promoter region of miR-126, and regulated the expression of miR-126 and EGFL7. Conclusion: We demonstrated the first evidence that miR-126 possesses its own independent promoter and could be regulated by NF-κB3 directly. Our study provides further insights into the regulatory mechanisms for the upregulation of miRNA in inflammatory conditions like UC.