Characterization of a Novel Nuclear Hormone Receptor Coactivator, Uba3, and Its Function in Breast Cancer
Abstract
We previously reported that human ubiquitin-activating enzyme 3 (hUba3), a novel candidate coactivator protein, had been identified by our lab in a yeast 2-hybrid screen using the PR-LBD in the presence of RU4S6 as a bait protein. Human Uba3, as well as its hetero-dimeric binding partner, APP-BP 1, were able to enhance ligand- activated ERoc, PR-B, GR, AR, TRBeta, and RARalpha-dependent transcription in HeLa cells, although fold-activation was highest with ERalpha and PR-B. In a classic reverse-squelching experiment between ERalpha and PR-B, we demonstrated that both hUba3 and APP-BP 1 exist in limiting quantities within the cellular milieu. Interestingly, hUba3 and APP-BP1 appear not to contain appreciable intrinsic activation functions nor demonstrate physical iii vitro associations with PR-B, suggesting these proteins may differ from other previously identified coactivators. Furthermore, hUba3 indirectly interacts with PR-B in a progesterone-dependent manner in a mammalian one hybrid system. Our observations suggest that hUba3 and APP-BPI do not fit any classic coactivator models and may be unique in their own right. We are currently developing a chromatin immunoprecipitation assay system to gain further insight as to how these proteins regulate steroid receptor-dependent transcription of endogenous target genes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2001
- Accession Number
- ADA391413
Entities
People
- Andrew Dennis
- Bert O'malley
Organizations
- Baylor College of Medicine