DRIP150 Coactivation of Estrogen Receptor α in ZR-75 Breast Cancer Cells Is Independent of LXXLL Motifs | Academic Article individual record
abstract

Vitamin D receptor-interacting protein 150 (DRIP150) has been identified as part of mediator-like complexes that enhance transcriptional activation of the estrogen receptor (ER) and other nuclear receptors (NRs). DRIP150 coactivates ligand-dependent ERalpha-mediated transactivation in ZR-75 and MDA-MB-231 breast cancer cells transfected with a (luciferase) reporter construct (pERE3) regulated by three tandem estrogen-responsive elements. Coactivation of ERalpha by DRIP150 in ZR-75 cells was activation function 2-dependent and required an intact helix 12 that typically interacts with LXXLL motifs (NR box) in p160 steroid receptor coactivators. DRIP150 contains C- and N-terminal NR boxes (amino acids 1182-1186 and 69-73, respectively), and deletion analysis of DRIP150 showed that regions containing these sequences were not necessary for coactivation of ERalpha. Analysis of multiple DRIP150 deletion mutants identified a 23-amino-acid sequence (789-811) required for coactivation activity. Analysis of the protein crystal structure data base identified two regions at amino acids 789-794 and 795-804, which resembled alpha-helical motifs in Lanuginosa lipase/histamine N-methyltransferase and hepatocyte nuclear factor 1, respectively. By using a squelching assay and specific amino acid point mutations within each alpha-helix, the NIFSEVRVYN (795-804) region was identified as the critical sequence required for the activity of DRIP150. These results demonstrate that coactivation of ERalpha by DRIP150 in ZR-75 cells is NR box-independent and requires a novel sequence with putative alpha-helical structure.

author list (cited authors)
Lee, J. E., Kim, K., Sacchettini, J. C., Smith, C. V., & Safe, S.
publication date
2005
keywords
  • Cell Line, Tumor
  • Binding Sites
  • DNA Primers
  • Female
  • Molecular Sequence Data
  • Base Sequence
  • Amino Acid Sequence
  • Mediator Complex
  • Estrogen Receptor Alpha
  • Breast Neoplasms
  • Humans
  • Trans-Activators
citation count

19