miR-346 and miR-138 competitively regulate hTERT in GRSF1- and AGO2-dependent manners, respectively

Sci Rep. 2015 Oct 28:5:15793. doi: 10.1038/srep15793.

Abstract

miRNAs typically downregulate the expression of target genes by binding to their 3'UTR, and dysregulation of miRNAs may contribute to tumorigenesis. Here, we found that miR-346 and miR-138 competitively bind to a common region in the 3'UTR of hTERT mRNA and have opposite effects on the expression and function of hTERT in human cervical cancer cells. Furthermore, G-rich RNA sequence binding factor 1 (GRSF1) mediates the miR-346-dependent upregulation of hTERT by binding to the miR-346 middle sequence motif (CCGCAU) which forms a "bulge loop" when miR-346 is bound to the hTERT 3'UTR, facilitating the recruitment of hTERT mRNA to ribosomes to promote translation in an AGO2-independent manner. Conversely, miR-138 suppresses hTERT expression in an AGO2-dependent manner. Interestingly, replacement of the miR-138 middle sequence with that of miR-346 results in an upregulation of hTERT expression in a GRSF1-dependent manner. Moreover, miR-346 depends on GRSF1 to upregulate another target gene, activin A receptor, type IIB (ACVR2B), in which miR-346 "CCGCAU" motif is essential. These findings reveal novel mechanisms of miRNA-mediated upregulation of target gene expression and describe the coordinated action of multiple miRNAs to control the fate of a single target mRNA through binding to its 3'UTR.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3' Untranslated Regions / genetics
  • Animals
  • Argonaute Proteins / genetics*
  • Cell Line, Tumor
  • Down-Regulation / genetics
  • Female
  • Gene Expression Regulation, Neoplastic / genetics
  • HeLa Cells
  • Humans
  • Mice, Inbred BALB C
  • Mice, Nude
  • MicroRNAs / genetics*
  • Poly(A)-Binding Proteins / genetics*
  • Telomerase / genetics*

Substances

  • 3' Untranslated Regions
  • AGO2 protein, human
  • Argonaute Proteins
  • GRSF1 protein, human
  • MIRN138 microRNA, human
  • MIRN346 microRNA, human
  • MicroRNAs
  • Poly(A)-Binding Proteins
  • TERT protein, human
  • Telomerase