Two distinct nuclear receptor-interaction domains and CREB-binding protein-dependent transactivation function of activating signal cointegrator-2

Mol Endocrinol. 2001 Feb;15(2):241-54. doi: 10.1210/mend.15.2.0595.

Abstract

ASC-2 is a recently isolated transcriptional cointegrator molecule, which is amplified in human cancers and stimulates transactivation by nuclear receptors, AP-1, nuclear factor kappaB (NFkappaB), serum response factor (SRF), and numerous other transcription factors. ASC-2 contained two nuclear receptor-interaction domains, both of which are dependent on the integrity of their core LXXLL sequences. Surprisingly, the C-terminal LXXLL motif specifically interacted with oxysterol receptor LXRss, whereas the N-terminal motif bound a broad range of nuclear receptors. These interactions appeared to be essential because a specific subregion of ASC-2 including the N- or C-terminal LXXLL motif acted as a potent dominant negative mutant with transactivation by appropriate nuclear receptors. In addition, the autonomous transactivation domain (AD) of ASC-2 was found to consist of three separable subregions; i.e. AD1, AD2, and AD3. In particular, AD2 and AD3 were binding sites for CREB binding protein (CBP), and CBP-neutralizing E1A repressed the autonomous transactivation function of ASC-2. Furthermore, the receptor transactivation was not enhanced by ASC-2 in the presence of E1A and significantly impaired by overexpressed AD2. From these results, we concluded that ASC-2 directly binds to nuclear receptors and recruits CBP to mediate the nuclear receptor transactivation in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • CREB-Binding Protein
  • Cell Line
  • Escherichia coli
  • Gene Expression
  • Glutathione Transferase / genetics
  • HeLa Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins*
  • Mice
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / metabolism
  • Nuclear Proteins / pharmacology*
  • Nuclear Receptor Coactivators
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism
  • Plasmids / genetics
  • Polymerase Chain Reaction
  • Protein Structure, Secondary
  • Receptors, Cytoplasmic and Nuclear / metabolism*
  • Receptors, Steroid / metabolism
  • Receptors, Thyroid Hormone / chemistry
  • Receptors, Thyroid Hormone / metabolism
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae / enzymology
  • Structure-Activity Relationship
  • Trans-Activators / chemistry
  • Trans-Activators / metabolism
  • Trans-Activators / pharmacology*
  • Transcription Factors / chemistry*
  • Transcription Factors / genetics
  • Transcription Factors / physiology*
  • Transcriptional Activation*
  • Transfection
  • beta-Galactosidase / genetics

Substances

  • Intracellular Signaling Peptides and Proteins
  • NCOA6 protein, human
  • Ncoa6 protein, mouse
  • Nuclear Proteins
  • Nuclear Receptor Coactivators
  • Peptide Fragments
  • Receptors, Cytoplasmic and Nuclear
  • Receptors, Steroid
  • Receptors, Thyroid Hormone
  • Recombinant Fusion Proteins
  • Trans-Activators
  • Transcription Factors
  • oxysterol binding protein
  • CREB-Binding Protein
  • CREBBP protein, human
  • Crebbp protein, mouse
  • Glutathione Transferase
  • beta-Galactosidase