Smad-mediated regulation of microRNA biosynthesis

microRNAs (miRNAs) are small non-coding RNAs conserved in metazoans. Depletion of miRNAs results in embryonic lethality, suggesting they are essential for embryogenesis. Similarly, pathways induced by growth factors of the transforming growth factor beta (TGF-beta) superfamily control cell growth, differentiation, and development. Recently Smad proteins, the signal transducers of the TGF-beta pathway, were found to regulate miRNA expression, which, in turn, affects expression of numerous proteins. Smads modulate miRNA expression through both transcriptional and post-transcriptional mechanisms illustrating the complexity of gene regulation by TGF-beta. In this chapter we summarize the current knowledge of mechanisms underlying Smad-mediated regulation of miRNA biogenesis. (C) 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.