title: HTLV-1 basic leucine-zipper factor, HBZ, interacts with MafB and suppresses transcription through a Maf recognition element.
abstract: HTLV-1 infection causes adult T-cell leukemia (ATL). The development of ATL is thought to be associated with disruption of transcriptional control of cellular genes. HTLV-1 basic leucine-zipper (bZIP) factor, HBZ, is encoded by the complementary strand of the provirus. We previously reported that HBZ interacts with c-Jun and suppresses its transcriptional activity. To identify the cellular factor(s) that interact with HBZ, we conducted a yeast two-hybrid screen using full-length HBZ as bait and identified MafB. HBZ heterodimerizes with MafB via each bZIP domain. Luciferase analysis revealed a significant decrease in transcription through Maf recognition element (MARE) in a manner dependent on the bZIP domain of HBZ. Indeed, production of full-length HBZ in cells decreased the MARE-bound MafB protein, indicating that HBZ abrogates the DNA-binding activity of MafB. In addition, HBZ reduced the steady-state levels of MafB, and the levels were restored by treatment with a proteasome inhibitor. These results suggest a suppressive effect of HBZ on Maf function, which may have a significant role in HTLV-1 related pathogenesis.
authors.affiliation: Faculty of Pharmaceutical Science at Kagawa Campus, Tokushima Bunri University, Kagawa, Japan. ohshimat@kph.bunri-u.ac.jp
authors.forename: Takayuki
authors.initials: T
authors.lastname: Ohshima
authors.forename: Risa
authors.initials: R
authors.lastname: Mukai
authors.forename: Norie
authors.initials: N
authors.lastname: Nakahara
authors.forename: Jun
authors.initials: J
authors.lastname: Matsumoto
authors.forename: Osamu
authors.initials: O
authors.lastname: Isono
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Satoru
authors.initials: S
authors.lastname: Takahashi
authors.forename: Kunitada
authors.initials: K
authors.lastname: Shimotohno
mesh_terms: D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015967:Gene Expression Regulation, Viral; D057809:HEK293 Cells; D006367:HeLa Cells; D015368:Human T-lymphotropic virus 1 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D016350:Leucine Zippers; D051258:MafB Transcription Factor / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D050436:Regulatory Elements, Transcriptional; D012191:Retroviridae Proteins; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; C479751:HBZ protein, human T-cell leukemia virus type I; D051258:MafB Transcription Factor; D012191:Retroviridae Proteins; D014764:Viral Proteins; D046988:Proteasome Endopeptidase Complex