title: Identification of APOBEC3B promoter elements responsible for activation by human papillomavirus type 16 E6.
abstract: Recent cancer genomics studies have identified mutation patterns characteristic of APOBEC3B (A3B) in multiple cancers, including cervical cancer, which is caused by human papillomavirus (HPV) infection. A3B expression is upregulated by HPV E6/E7 oncoproteins, implying a crucial role for A3B upregulation in HPV-induced carcinogenesis. Here, we explored the molecular mechanisms underlying the activation of the A3B promoter by E6. Luciferase reporter assays with a series of deleted fragments of the human A3B promoter in normal immortalized human keratinocytes (NIKS) identified two functional regions in the promoter: the distal region (from -200 to -51), which is required for basal promoter activity, and the proximal region (from +1 to +45), which exerts an inhibitory effect on gene expression. Each promoter region was found to contain an E6-responsive element(s). Disruption of an AT-rich motif located between +10 and +16 abrogated the proximal-region-mediated activation of the A3B promoter by E6. DNA pull-down assays revealed that a cellular zinc-finger protein, ZNF384, binds to the AT-rich motif in the A3B promoter, and chromatin immunoprecipitation assays confirmed that ZNF384 binds to the A3B promoter in cells. ZNF384 knockdown reduced the A3B mRNA levels in NIKS expressing E6, but not in the parental NIKS, indicating that ZNF384 contributes to A3B upregulation by E6, but not to basal A3B expression. The exogenous expression of ZNF384 led to the activation of the A3B promoter in NIKS. Collectively, these results indicate that E6 activates the A3B promoter through the distal and proximal regions, and that ZNF384 is required for the proximal-region-mediated activation of A3B.
authors: Pathogen Genomics Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan. Electronic address: moris@nih.go.jp.
authors: Seiichiro
authors: S
authors: Mori
authors: Pathogen Genomics Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan.
authors: Takamasa
authors: T
authors: Takeuchi
authors: Pathogen Genomics Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan.
authors: Yoshiyuki
authors: Y
authors: Ishii
authors: Pathogen Genomics Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan.
authors: Iwao
authors: I
authors: Kukimoto
mesh_terms: D001483:Base Sequence; D002461:Cell Line, Transformed; D003564:Cytidine Deaminase / Q000235:genetics* / Q000378:metabolism; D004247:DNA; D055785:Gene Knockdown Techniques; D006801:Humans; D015778:Minor Histocompatibility Antigens; D008969:Molecular Sequence Data; D009856:Oncogene Proteins, Viral / Q000502:physiology*; D011401:Promoter Regions, Genetic; D034741:RNA, Small Interfering; D012097:Repressor Proteins / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism
chemical_list: C068651:E6 protein, Human papillomavirus type 16; D015778:Minor Histocompatibility Antigens; D009856:Oncogene Proteins, Viral; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D015534:Trans-Activators; C498621:ZNF384 protein, human; D004247:DNA; C495794:APOBEC3B protein, human; D003564:Cytidine Deaminase
keywords: APOBEC3B; E6; Human papillomavirus; Promoter; ZNF384