title: Human ADA3 binds to estrogen receptor (ER) and functions as a coactivator for ER-mediated transactivation.
abstract: We have recently identified the hADA3 protein, the human homologue of yeast transcriptional coactivator yADA3, as a novel HPV16 E6 target. Using ectopic expression approaches, we further demonstrated that hADA3 directly binds to the 9-cis retinoic acid receptors alpha and beta, and functions as a coactivator for retinoid receptor-mediated transcriptional activation. Here, we examined the role of endogenous hADA3 as a coactivator for estrogen receptor (ER), an important member of the nuclear hormone receptor superfamily. We show that ADA3 directly interacts with ER alpha and ER beta. Using the chromatin immunoprecipitation assay, we also show that hADA3 is a component of the activator complexes bound to the native ER response element within the promoter of the estrogen-responsive gene pS2. Furthermore, using an ER response element-luciferase reporter, we show that overexpression of ADA3 enhances the ER alpha- and ER beta-mediated sequence-specific transactivation. Reverse transcription-PCR analysis showed an ADA3-mediated increase in estrogen-induced expression of the endogenous pS2 gene. More importantly, using RNA interference against hADA3, we demonstrate that inhibition of endogenous hADA3 inhibited ER-mediated transactivation and the estrogen-induced increase in the expression of pS2, cathepsin D, and progesterone receptor, three widely known ER-responsive genes. The HPV E6 protein, by targeting hADA3 for degradation, inhibited the ER alpha-mediated transactivation and the protein expression of ER target genes. Thus, our results demonstrate that ADA3 directly binds to human estrogen receptor and enhances the transcription of ER-responsive genes, suggesting a broader role of mammalian hADA3 as a coactivator of nuclear hormone receptors and the potential role of these pathways in HPV oncogenesis.
authors.affiliation: Department of Radiation Oncology, New England Medical Center, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
authors.forename: Gaoyuan
authors.initials: G
authors.lastname: Meng
authors.forename: Yongtong
authors.initials: Y
authors.lastname: Zhao
authors.forename: Alo
authors.initials: A
authors.lastname: Nag
authors.forename: Musheng
authors.initials: M
authors.lastname: Zeng
authors.forename: Goberdhan
authors.initials: G
authors.lastname: Dimri
authors.forename: Qingshen
authors.initials: Q
authors.lastname: Gao
authors.forename: David E
authors.initials: DE
authors.lastname: Wazer
authors.forename: Rakesh
authors.initials: R
authors.lastname: Kumar
authors.forename: Hamid
authors.initials: H
authors.lastname: Band
authors.forename: Vimla
authors.initials: V
authors.lastname: Band
mesh_terms: D002402:Cathepsin D / Q000235:genetics; D002460:Cell Line; D047628:Estrogen Receptor alpha / Q000378:metabolism / Q000502:physiology*; D047629:Estrogen Receptor beta / Q000378:metabolism / Q000502:physiology*; D004967:Estrogens / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D005982:Glutathione Transferase / Q000235:genetics; D006801:Humans; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000502:physiology; D027383:Papillomaviridae; D011506:Proteins / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics / Q000502:physiology; D011980:Receptors, Progesterone / Q000235:genetics; D011993:Recombinant Fusion Proteins; D020218:Response Elements / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015533:Transcriptional Activation / Q000502:physiology*; D000071163:Trefoil Factor-1; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins
chemical_list: D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D004967:Estrogens; D009856:Oncogene Proteins, Viral; D011506:Proteins; D034741:RNA, Small Interfering; D011980:Receptors, Progesterone; D011993:Recombinant Fusion Proteins; C444103:TADA3 protein, human; C051838:TFF1 protein, human; D014157:Transcription Factors; D000071163:Trefoil Factor-1; D025521:Tumor Suppressor Proteins; D005982:Glutathione Transferase; D002402:Cathepsin D