ROCK inhibition enhances microRNA function by promoting deadenylation of targeted mRNAs via increasing PAIP2 expression.
Bottom Line: Here, we report that global miRNA function can be enhanced by Rho-associated, coiled-coil-containing protein kinase (ROCK) inhibitors.In the presence of a ROCK inhibitor, PAIP2 expression is enhanced by the transcription factor hepatocyte nuclear factor 4 alpha (HNF4A) through increased ROCK1 nuclear localization and enhanced ROCK1 association with HNF4A.Our data reveal an unexpected role of ROCK1 as a cofactor of HNF4A in enhancing PAIP2 transcription.
Affiliation: Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan.Show MeSH
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Mentions: To date, there is no information on the relationship between ROCK inhibition and miRNA function. We noticed that prolonged pretreatment with Y27632 was required to detect increased decay of miRNA-targeted mRNA when ActD was used to block global transcription (Figure 2C). Y27632 had no detectable effect when applied simultaneously with ActD. One possibility is that ROCK inhibition induces de novo protein synthesis and that newly synthesized proteins function to enhance miRNA-targeted mRNA degradation. To evaluate this, we compared the decay of a β-globin reporter mRNA driven by a Tet-off promoter after addition of Dox or ActD with or without Y27632. When transcription of a β-globin reporter mRNA containing wild-type let-7 binding sites was blocked by Dox, the ROCK inhibitor enhanced mRNA decay; however, when transcription was inhibited by ActD, the ROCK inhibitor had no detectable effect (Figure 3A). Thus ROCK inhibitors most likely require de novo protein synthesis to enhance miRNA function.
Affiliation: Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan.