Multiple mechanisms of growth hormone-regulated gene transcription

Mol Genet Metab. 2007 Feb;90(2):126-33. doi: 10.1016/j.ymgme.2006.10.006. Epub 2006 Nov 28.

Abstract

Diverse physiological actions of growth hormone (GH) are mediated by changes in gene transcription. Transcription can be regulated at several levels, including post-translational modification of transcription factors, and formation of multiprotein complexes involving transcription factors, co-regulators and additional nuclear proteins; these serve as targets for regulation by hormones and signaling pathways. Evidence that GH regulates transcription at multiple levels is exemplified by analysis of the proto-oncogene c-fos. Among the GH-regulated transcription factors on c-fos, C/EBPbeta appears to be key, since depletion of C/EBPbeta by RNA interference blocks the stimulation of c-fos by GH. The phosphorylation state of C/EBPbeta and its ability to activate transcription are regulated by GH through MAPK and PI3K/Akt-mediated signaling cascades. The acetylation of C/EBPbeta also contributes to its ability to activate c-fos transcription. These and other post-translational modifications of C/EBPbeta appear to be integrated for regulation of transcription by GH. The formation of nuclear proteins into complexes associated with DNA-bound transcription factors is also regulated by GH. Both C/EBPbeta and the co-activator p300 are recruited to c-fos in response to GH, altering c-fos promoter activation. In addition, GH rapidly induces spatio-temporal re-localization of C/EBPbeta within the nucleus. Thus, GH-regulated gene transcription mediated by C/EBPbeta reflects the integration of diverse mechanisms including post-translational modifications, modulation of protein complexes associated with DNA and re-localization of gene regulatory proteins. Similar integration involving other transcription factors, including Stats, appears to be a feature of regulation by GH of other gene targets.

Publication types

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

MeSH terms

  • Animals
  • CCAAT-Enhancer-Binding Protein-beta / genetics
  • CCAAT-Enhancer-Binding Protein-beta / metabolism
  • Gene Expression Regulation*
  • Genes, fos
  • Growth Hormone / metabolism*
  • Humans
  • Nucleoproteins / chemistry
  • Nucleoproteins / metabolism
  • Protein Processing, Post-Translational
  • Proto-Oncogene Mas
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Transcription, Genetic*

Substances

  • CCAAT-Enhancer-Binding Protein-beta
  • MAS1 protein, human
  • Nucleoproteins
  • Proto-Oncogene Mas
  • Transcription Factors
  • Growth Hormone