Mutation of histidine 874 in the androgen receptor ligand-binding domain leads to promiscuous ligand activation and altered p160 coactivator interactions

Mol Endocrinol. 2005 Dec;19(12):2943-54. doi: 10.1210/me.2005-0231. Epub 2005 Aug 4.

Abstract

The androgen receptor (AR) signaling pathway is a major therapeutic target in the treatment of prostate cancer. The AR functions as a ligand-activated transcription factor in the presence of the cognate hormone ligands testosterone and dihydrotestosterone (DHT). We have characterized a highly conserved sequence at the C-terminal end of helix 10/11 in the ligand-binding domain (LBD), which is prone to receptor point mutations in prostate cancer. This sequence includes threonine 877 that is involved in hydrogen bonding to the D ring of the steroid molecule and leads to promiscuous ligand activation of the AR when mutated to alanine or serine. A second mutation in this region, H874Y, also results in a receptor protein that has broadened ligand-binding specificity, but retains an affinity for DHT (K(d) = 0.77 nm) similar to that of the wild-type receptor. The structure of the mutant LBD, expressed in Escherichia coli, is not dramatically altered compared with the wild-type AR-LBD in the presence of DHT, but shows a modestly increased sensitivity to protease digestion in the absence of hormone. This mutant AR showed wild-type AR-LBD/N-terminal domain interactions, but significantly enhanced binding and transactivation activity with all three members of the p160 family of coactivator proteins. Together, these phenotypic changes are likely to confer a selective advantage for tumor cells in a low androgen environment resulting from hormone therapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Substitution
  • Animals
  • Conserved Sequence
  • Escherichia coli / genetics
  • Histidine / genetics*
  • Humans
  • Ligands
  • Male
  • Molecular Sequence Data
  • Nuclear Receptor Coactivator 2 / metabolism
  • Point Mutation
  • Prostatic Neoplasms / genetics*
  • Protein Interaction Mapping
  • Protein Structure, Tertiary
  • Receptors, Androgen / chemistry
  • Receptors, Androgen / genetics*
  • Receptors, Androgen / metabolism*
  • Trans-Activators / metabolism*

Substances

  • Ligands
  • Nuclear Receptor Coactivator 2
  • Receptors, Androgen
  • Trans-Activators
  • Histidine