1. miR-195 plays a role in steroid resistance of ulcerative colitis by targeting Smad7.
- Author
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Chen G, Cao S, Liu F, and Liu Y
- Subjects
- 3' Untranslated Regions, Adult, Caco-2 Cells, Colitis, Ulcerative blood, Colitis, Ulcerative drug therapy, Female, Gene Expression Regulation drug effects, Humans, Male, MicroRNAs biosynthesis, MicroRNAs blood, Middle Aged, Proto-Oncogene Proteins c-jun biosynthesis, Proto-Oncogene Proteins c-jun blood, Signal Transduction genetics, Smad7 Protein biosynthesis, Smad7 Protein blood, Transcription Factor AP-1 biosynthesis, Transcription Factor AP-1 blood, eIF-2 Kinase biosynthesis, eIF-2 Kinase blood, Colitis, Ulcerative genetics, Drug Resistance genetics, MicroRNAs genetics, Smad7 Protein genetics, Steroids therapeutic use
- Abstract
An imbalance in pro- and anti-inflammation is an important mechanism of steroid resistance in UC (ulcerative colitis), and miRNAs may participate in this process. The present study aimed to explore whether miRNAs play a role in the steroid resistance of UC by regulating gene expression of the inflammation signal pathway. SS (steroid-sensitive) patients, SR (steroid-resistant) patients and healthy individuals were recruited. In vivo miRNA profiles of serum samples showed that miR-195 was decreased significantly in the SR group compared with the SS group (P<0.05). This result was confirmed by qPCR (quantitative real-time PCR) and miRNA ISH (in situ hybridization) in serum and colon tissue samples. Online software was used to identify Smad7 mRNA as a potential target of miR-195. The direct interaction of miR-195 and Smad7 mRNA was investigated using a biotinylated miR-195 pull-down assay. Overexpression of a miR-195 precursor lowered cellular levels of Smad7 protein; conversely, antagonism of miR-195 enhanced Smad7 translation without disturbing Smad7 mRNA levels. A luciferase reporter assay revealed a repressive effect of miR-195 via a single Smad7 3'-UTR target site, and point mutation of this site prevented miR-195-induced repression of Smad7 translation. Furthermore, increased levels of miR-195 led to a decrease in c-Jun and p65 expression. In contrast, transfection with anti-miR-195 led to increased levels of c-Jun and p65 protein. The decrease in miR-195 led to an increase in Smad7 expression and corresponding up-regulation of p65 and the AP-1 (activator protein 1) pathway, which might explain the mechanism of steroid resistance in UC patients., (© 2015 Authors; published by Portland Press Limited.)
- Published
- 2015
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