Steroidogenic factor-1 contains a carboxy-terminal transcriptional activation domain that interacts with steroid receptor coactivator-1

Mol Endocrinol. 1998 Feb;12(2):290-301. doi: 10.1210/mend.12.2.0059.

Abstract

The orphan nuclear receptor, steroidogenic factor-1 (SF-1), plays an important role in the development of the adrenal gland and in sexual differentiation. SF-1 regulates the transcription of variety of genes, including several steroidogenic enzymes, Müllerian inhibiting substance, and gonadotropin genes. In this report, we sought to identify domains in SF-1 that are required for transactivation and to determine whether SF-1 interacts with a subset of known coactivators. Natural variants of the FTZ-F1 locus include embryonal long terminal repeat-binding protein (ELP)-1, ELP-2, and SF-1, which share the DNA-binding domain. Analyses of the transcriptional activity of these variants revealed that the activity of ELP-2 and SF-1 was much greater than ELP-1, which contains a distinct carboxy terminus. Further studies were performed using GAL4-SF-1 fusion proteins that were constructed by replacement of the zinc finger region and FTZ-F1 box of SF-1 with the DNA-binding domain of GAL4. Elimination of the putative AF-2 domain at the carboxy terminus of GAL4-SF-1 proteins resulted in a complete loss of transactivation. Several lines of evidence demonstrated that SF-1 interacts with steroid receptor coactivator-1 (SRC-1). Full-length SRC-1 enhanced GAL4-SF-1-mediated transactivation, whereas a dominant negative form of SRC-1, consisting of its interaction domain alone, inhibited the activity of GAL4-SF-1. In mammalian two-hybrid assays, fusion of the VP16 activation domain to the interaction domain of SRC-1 confirmed the interaction between SRC-1 and GAL4-SF-1 and demonstrated that the AF-2 domain is required for interaction with SRC-1. Furthermore, SRC-1, together with the cAMP responsive element binding protein (CBP) or a closely related factor, p300, synergistically enhanced transcriptional activity of GAL4-SF-1. We conclude that the carboxy-terminal AF-2 region of SF-1 functions as an activation domain and that SRC-1 and CBP/p300 are components of the coactivator complex with SF-1.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cell Line
  • DNA-Binding Proteins / metabolism*
  • Drug Synergism
  • Fushi Tarazu Transcription Factors
  • Histone Acetyltransferases
  • Homeodomain Proteins
  • Humans
  • Mice
  • Molecular Sequence Data
  • Nuclear Receptor Coactivator 1
  • Nuclear Receptor Coactivator 3
  • Protein Structure, Tertiary / drug effects
  • Receptors, Cytoplasmic and Nuclear
  • Receptors, Steroid / metabolism*
  • Steroidogenic Factor 1
  • Trans-Activators / metabolism
  • Transcription Factors / metabolism*
  • Transcriptional Activation* / drug effects
  • Tumor Cells, Cultured

Substances

  • DNA-Binding Proteins
  • Fushi Tarazu Transcription Factors
  • Homeodomain Proteins
  • NR5A1 protein, human
  • Receptors, Cytoplasmic and Nuclear
  • Receptors, Steroid
  • Steroidogenic Factor 1
  • Trans-Activators
  • Transcription Factors
  • steroidogenic factor 1, mouse
  • Histone Acetyltransferases
  • NCOA1 protein, human
  • NCOA3 protein, human
  • Ncoa1 protein, mouse
  • Ncoa3 protein, mouse
  • Nuclear Receptor Coactivator 1
  • Nuclear Receptor Coactivator 3