title: COBRA1 inhibits AP-1 transcriptional activity in transfected cells.
abstract: Mutations in the breast cancer susceptibility gene (BRCA1) account for a significant proportion of hereditary breast and ovarian cancers. Cofactor of BRCA1 (COBRA1) was isolated as a BRCA1-interacting protein and exhibited a similar chromatin reorganizing activity to that of BRCA1. However, the biological role of COBRA1 remains largely unexplored. Here, we report that ectopic expression of COBRA1 inhibited activator protein 1 (AP-1) transcriptional activity in transfected cells in a dose-dependent manner, whereas reduction of endogenous COBRA1 with a small interfering RNA significantly enhanced AP-1-mediated transcriptional activation. COBRA1 physically interacted with the AP-1 family members, c-Jun and c-Fos, and the middle region of COBRA1 bound to c-Fos. Lack of c-Fos binding site in the COBRA1 completely abolished the COBRA1 inhibition of AP-1 trans-activation. These findings suggest that COBRA1 may directly modulate AP-1 pathway and, therefore, may play important roles in cell proliferation, differentiation, apoptosis, and oncogenesis.
authors.affiliation: Beijing Institute of Biotechnology, 27 Tai-Ping Lu Rd, Beijing 100850, PR China.
authors.forename: Hongjun
authors.initials: H
authors.lastname: Zhong
authors.forename: Jianhua
authors.initials: J
authors.lastname: Zhu
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.forename: Lihua
authors.initials: L
authors.lastname: Ding
authors.forename: Yan
authors.initials: Y
authors.lastname: Sun
authors.forename: Cuifen
authors.initials: C
authors.lastname: Huang
authors.forename: Qinong
authors.initials: Q
authors.lastname: Ye
mesh_terms: D001665:Binding Sites; D002460:Cell Line; D017353:Gene Deletion; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011485:Protein Binding; D016760:Proto-Oncogene Proteins c-fos / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014157:Transcription Factors; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D009687:Nuclear Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D018808:Transcription Factor AP-1; D014157:Transcription Factors; C118437:negative elongation factor; D005982:Glutathione Transferase