Novel interaction between HPV E6 and BARD1 (BRCA1-associated ring domain 1) and its biologic roles.
Human papillomaviruses (HPVs), which are associated with the majority of cervical cancers, encode a transforming protein, E6, which interacts with the p53 tumor suppressor protein. There is a wide effort focused on searching for the target of the involvement of p53-independent HPV 16 E6-interacting proteins. We identified Breast Cancer 1 Gene (BRCA1)-associated ring domain protein 1 (BARD1) as a binding partner of E6 and investigated its biological function in cervical cancer cells. In vivo co-immunoprecipitation assay was performed to determine whether E6-BARD1 interaction occurred. We then used a degradation assay to determine whether E6-mediated inactivation of BARD1 transactivation function was associated with BARD1 degradation. A mutation assay revealed the site of interaction of E6 with BARD1. The effect of BARD1 on p53 transcriptional activity was tested using BARD1 knockdown and overexpression systems. BARD1 was not degraded by E6, and, instead, formed a physical complex with E6. Moreover, the mutations of the metal motif zinc-finger region decreased the ability of E6 to interact with BARD1. Transient transfection of BARD1 increased the p53-mediated activation of p21(WAF1) promoter despite the presence of E6. Additionally, the existence of BARD1 inactivated the expression of E6 in cervical cancer cells. These findings suggest that BARD1 may regulate the transcriptional activities of p53 as tumor suppressors.
Yim
Eun-Kyoung
EK
Department of Obstetrics and Gynecology, The Catholic University of Korea, Seoul, Republic of Korea.
Lee
Keun-Ho
KH
Myeong
Jin
J
Tong
Seo-Yun
SY
Um
Soo-Jong
SJ
Park
Jong-Sup
JS
D000595:Amino Acid Sequence; D000818:Animals; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D005260:Female; D052162:Human papillomavirus 16; D006801:Humans; D008969:Molecular Sequence Data; D009856:Oncogene Proteins, Viral / Q000378:metabolism*; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism*; D015533:Transcriptional Activation; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D002583:Uterine Cervical Neoplasms
C068651:E6 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; D012097:Repressor Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C102449:BARD1 protein, human; D044767:Ubiquitin-Protein Ligases