title: [XBP-1 interacts with estrogen receptor alpha (ERalpha)].
abstract: Estrogen receptor alpha (ERalpha) has been a primary target of treatment as well as a prognostic indicator for breast cancer. The level of human X-box binding protein 1 (XBP-1) mRNA was related with that of ERalpha in breast tumors and was over-expressed in some breast tumors. These previous studies suggested that XBP-1 may interact with ERalpha. XBP-1 has two isoforms, XBP-1S and XBP-1U, as the result of unique splicing. GST pull-down assay showed that both XBP-1S and XBP-1U bound to ERalpha in vitro. The binding of XBP-1S to ERalpha was stronger than that of XBP-1U to ERalpha. Co-immunoprecipitation revealed that the binding was in a ligand-independent manner. XBP-1S and XBP-1U interacted with the region of ERalpha that contains a DNA-binding domain. The ERalpha-interacting regions on XBP-1S and XBP-1U have been mapped to two regions, the N-terminal basic region leucine zipper domain (bzip) and the C-terminal activation domain. These findings suggest that XBP-1S and XBP-1U may participate in ERalpha signaling pathway through the mediation of ERalpha.
authors.affiliation: Beijing Institute of Biotechnology, Beijing 100850, China.
authors.forename: Li-Hua
authors.initials: LH
authors.lastname: Ding
authors.forename: Qi-Nong
authors.initials: QN
authors.lastname: Ye
authors.forename: Jing-Hua
authors.initials: JH
authors.lastname: Yan
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Zhu
authors.forename: Qiu-Jun
authors.initials: QJ
authors.lastname: Lü
authors.forename: Zong-Hua
authors.initials: ZH
authors.lastname: Wang
authors.forename: Cui-Fen
authors.initials: CF
authors.lastname: Huang
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D054730:Protein Interaction Domains and Motifs / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D000071701:Regulatory Factor X Transcription Factors; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D000071717:X-Box Binding Protein 1
chemical_list: D004268:DNA-Binding Proteins; D047628:Estrogen Receptor alpha; D012333:RNA, Messenger; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605543:XBP1 protein, human