Development of a Novel Molecular Sensor for Imaging Estrogen Receptor-Coactivator Protein-Protein Interactions

ABSTRACT Nuclear receptors (NRs) regulate target gene transcription through the recruitment of multiple coactivator complexes to the promoter regions of target genes. One important coactivator complex includes a p160 coactivator (GRIP1, SRC-1, or ACTR) and its downstream coactivators (e.g., p300, CARM1, CoCoA, and Fli-I), which contribute to transcriptional activation by protein acetylation, protein methylation, and protein-protein interactions. In this study, we identified a novel NR coactivator, GAC63, which binds to the N-terminal region of p160 coactivators as well as the ligand binding domains of some NRs. GAC63 enhanced transcriptional activation by NRs in a hormone-dependent and GRIP1-dependent manner in transient transfection assays and cooperated synergistically and selectively with other NR coactivators, including GRIP1 and CARM1, to enhance estrogen receptor function. Endogenous GAC63 was recruited to the estrogen-responsive pS2 gene promoter of MCF-7 cells in response to the hormone. Reduction of the endogenous GAC63 level by small interfering RNA inhibited transcriptional activation by the hormone-activated estrogen receptor. Thus, GAC63 is a physiologically relevant part of the p160 coactivator signaling pathway that mediates transcriptional activation by NRs.

Download Full-text

Non-classical genomic estrogen receptor (ER)/specificity protein and ER/activating protein-1 signaling pathways

Journal of Molecular Endocrinology ◽

10.1677/jme-08-0103 ◽

2008 ◽

Vol 41 (5) ◽

pp. 263-275 ◽

Cited By ~ 198

Author(s):

Stephen Safe ◽

Kyoungkim Kim

Keyword(s):

Gene Expression ◽

Estrogen Receptor ◽

Protein Interactions ◽

Gene Promoters ◽

Protein Protein Interactions ◽

17Β Estradiol ◽

Promoter Dna ◽

Specificity Protein ◽

Activate Gene

17β-Estradiol binds to the estrogen receptor (ER) to activate gene expression or repression and this involves both genomic (nuclear) and non-genomic (extranuclear) pathways. Genomic pathways include the classical interactions of ligand-bound ER dimers with estrogen-responsive elements in target gene promoters. ER-dependent activation of gene expression also involves DNA-bound ER that subsequently interacts with other DNA-bound transcriptions factors and direct ER-transcription factor (protein–protein) interactions where ER does not bind promoter DNA. Ligand-induced activation of ER/specificity protein (Sp) and ER/activating protein-1 [(AP-1); consisting of jun/fos] complexes are important pathways for modulating expression of a large number of genes. This review summarizes some of the characteristics of ER/Sp- and ER/AP-1-mediated transactivation, which are dependent on ligand structure, cell context, ER-subtype (ERα and ERβ), and Sp protein (SP1, SP3, and SP4) and demonstrates that this non-classical genomic pathway is also functional in vivo.

Download Full-text

ZMIZ1 — A novel Estrogen Receptor co-activator that enhances the growth of ER+ breast cancer

10.1101/789610 ◽

2019 ◽

Author(s):

Anže Godicelj ◽

Ryan Blake ◽

Federico M Giorgi ◽

Marcel Gehrung ◽

Sanjeev Kumar ◽

...

Keyword(s):

Breast Cancer ◽

Estrogen Receptor ◽

Protein Interactions ◽

Quantitative Proteomics ◽

Breast Cancers ◽

Rna Seq ◽

Protein Protein Interactions ◽

Cell Cycle Genes ◽

Genome Wide ◽

Er Positive

AbstractThe Estrogen Receptor (ER) drives 75% of breast cancers. On activation, the ER recruits specific co-factors to form a transcriptionally active complex. These co-factors can modulate tumour growth and understanding their roles can help to identify new therapeutic targets.We applied a quantitative proteomics method, qPLEX-RIME, to analyse the ER protein complex and characterise changes in protein-protein interactions on activation. Our analysis identified ZMIZ1 as novel co-factor within the ER chromatin-bound complex, extending its known role as a co-factor of the Androgen Receptor. We find further evidence for an ER–ZMIZ1 interaction by showing that both proteins are co-expressed in biopsy samples. We characterise ZMIZ1 function by showing that targeting ZMIZ1 results in the reduction of ER transcriptional activity and significantly reduces the proliferation of ER-positive cell lines. We validated these results genome-wide by RNA-seq and identified that targeting ZMIZ1 resulted in a specific reduction of estradiol-induced cell cycle genes.These results establish ZMIZ1 as a having a key role in the ability of the ER to activate key genes that drive the proliferation of breast cancer, and its biological importance in patient tumours.

Download Full-text