Coordinate regulation of lipogenic gene expression by androgens: evidence for a cascade mechanism involving sterol regulatory element binding proteins

Proc Natl Acad Sci U S A. 1997 Nov 25;94(24):12975-80. doi: 10.1073/pnas.94.24.12975.

Abstract

To gain more insight into the molecular mechanisms by which androgens stimulate lipogenesis and induce a marked accumulation of neutral lipids in the human prostate cancer cell line LNCaP, we studied their impact on the expression of lipogenic enzymes. Northern blot analysis of the steady-state mRNA levels of seven different lipogenic enzymes revealed that androgens coordinately stimulate the expression of enzymes belonging to the two major lipogenic pathways: fatty acid synthesis and cholesterol synthesis. In view of the important role of the recently characterized sterol regulatory element binding proteins (SREBPs) in the coordinate induction of lipogenic genes, we examined whether the observed effects of androgens on lipogenic gene expression are mediated by these transcription factors. Our findings indicate that androgens stimulate the expression of SREBP transcripts and precursor proteins and enhance the nuclear content of the mature active form of the transcription factor. Moreover, by using the fatty acid synthase gene as an experimental paradigm we demonstrate that the presence of an SREBP-binding site is essential for its regulation by androgens. These data support the hypothesis that SREBPs are involved in the coordinate regulation of lipogenic gene expression by androgens and provide evidence for the existence of a cascade mechanism of androgen-regulated gene expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Androgens / physiology*
  • CCAAT-Enhancer-Binding Proteins*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / physiology*
  • Gene Expression Regulation / physiology*
  • Humans
  • Nuclear Proteins / genetics
  • Nuclear Proteins / physiology*
  • RNA, Messenger / genetics
  • Sterol Regulatory Element Binding Protein 1
  • Sterol Regulatory Element Binding Protein 2
  • Transcription Factors / genetics
  • Transcription Factors / physiology*
  • Tumor Cells, Cultured

Substances

  • Androgens
  • CCAAT-Enhancer-Binding Proteins
  • DNA-Binding Proteins
  • Nuclear Proteins
  • RNA, Messenger
  • SREBF1 protein, human
  • SREBF2 protein, human
  • Sterol Regulatory Element Binding Protein 1
  • Sterol Regulatory Element Binding Protein 2
  • Transcription Factors