Smad proteins bind a conserved RNA sequence to promote microRNA maturation by Drosha

Mol Cell. 2010 Aug 13;39(3):373-84. doi: 10.1016/j.molcel.2010.07.011.

Abstract

The signal transducers of the transforming growth factor beta (TGFbeta)/bone morphogenetic protein (BMP), the Smads, promote the expression of a subset of miRNAs by facilitating the cleavage reaction by Drosha. The mechanism that limits Smad-mediated processing to a selective group of miRNAs remained hitherto unexplored. In this study, we expand the number of TGFbeta/BMP-regulated miRNAs (T/B-miRs) to 20. Of interest, a majority of T/B-miRs contain a consensus sequence (R-SBE) within the stem region of the primary transcripts of T/B-miRs (pri-T/B-miRs). Here, we demonstrate that Smads directly bind the R-SBE. Mutation of the R-SBE abrogates TGFbeta/BMP-induced recruitment of Smads, Drosha, and DGCR8 to pri-T/B-miRs and impairs their processing, whereas introduction of R-SBE to unregulated pri-miRNAs is sufficient to recruit Smads and to allow regulation by TGFbeta/BMP. Thus, Smads are multifunctional proteins that modulate gene expression transcriptionally through DNA binding and posttranscriptionally through pri-miRNA binding and regulation of miRNA processing.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cells, Cultured
  • Humans
  • Matrix Metalloproteinases, Secreted / genetics
  • Matrix Metalloproteinases, Secreted / metabolism
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Protein Binding / drug effects
  • Protein Binding / physiology
  • Proteins / genetics
  • Proteins / metabolism
  • RNA Processing, Post-Transcriptional / drug effects
  • RNA Processing, Post-Transcriptional / physiology*
  • RNA-Binding Proteins
  • Regulatory Sequences, Ribonucleic Acid / physiology*
  • Ribonuclease III / genetics
  • Ribonuclease III / metabolism*
  • Smad Proteins / genetics
  • Smad Proteins / metabolism*
  • Transforming Growth Factor beta / pharmacology

Substances

  • DGCR8 protein, human
  • MicroRNAs
  • Proteins
  • RNA-Binding Proteins
  • Regulatory Sequences, Ribonucleic Acid
  • Smad Proteins
  • Transforming Growth Factor beta
  • DROSHA protein, human
  • Ribonuclease III
  • Matrix Metalloproteinases, Secreted