title: Bromodomain protein Brd4 plays a key role in Merkel cell polyomavirus DNA replication.
abstract: Merkel cell polyomavirus (MCV or MCPyV) is the first human polyomavirus to be definitively linked to cancer. The mechanisms of MCV-induced oncogenesis and much of MCV biology are largely unexplored. In this study, we demonstrate that bromodomain protein 4 (Brd4) interacts with MCV large T antigen (LT) and plays a critical role in viral DNA replication. Brd4 knockdown inhibits MCV replication, which can be rescued by recombinant Brd4. Brd4 colocalizes with the MCV LT/replication origin complex in the nucleus and recruits replication factor C (RFC) to the viral replication sites. A dominant negative inhibitor of the Brd4-MCV LT interaction can dissociate Brd4 and RFC from the viral replication complex and abrogate MCV replication. Furthermore, obstructing the physiologic interaction between Brd4 and host chromatin with the chemical compound JQ1(+) leads to enhanced MCV DNA replication, demonstrating that the role of Brd4 in MCV replication is distinct from its role in chromatin-associated transcriptional regulation. Our findings demonstrate mechanistic details of the MCV replication machinery; providing novel insight to elucidate the life cycle of this newly discovered oncogenic DNA virus.
authors.affiliation: Department of Microbiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Schowalter
authors.forename: Jing
authors.initials: J
authors.lastname: Jiao
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Buck
authors.forename: Jianxin
authors.initials: J
authors.lastname: You
mesh_terms: D000957:Antigens, Viral, Tumor / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D004261:DNA Replication; D004279:DNA, Viral / Q000096:biosynthesis* / Q000235:genetics; D057809:HEK293 Cells; D006801:Humans; D059965:Merkel cell polyomavirus / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D027601:Polyomavirus Infections / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014412:Tumor Virus Infections / Q000235:genetics / Q000378:metabolism; D014779:Virus Replication / Q000502:physiology*; D000092468:Bromodomain Containing Proteins
chemical_list: D000957:Antigens, Viral, Tumor; D018797:Cell Cycle Proteins; D002843:Chromatin; D004279:DNA, Viral; D009687:Nuclear Proteins; D014157:Transcription Factors; C441289:BRD4 protein, human; D000092468:Bromodomain Containing Proteins