title: BET-Inhibitors Disrupt Rad21-Dependent Conformational Control of KSHV Latency.
abstract: Kaposi's Sarcoma-associated Herpesvirus (KSHV) establishes stable latent infection in B-lymphocytes and pleural effusion lymphomas (PELs). During latency, the viral genome persists as an epigenetically constrained episome with restricted gene expression programs. To identify epigenetic regulators of KSHV latency, we screened a focused small molecule library containing known inhibitors of epigenetic factors. We identified JQ1, a Bromodomain and Extended Terminal (BET) protein inhibitor, as a potent activator of KSHV lytic reactivation from B-cells carrying episomal KSHV. We validated that JQ1 and other BET inhibitors efficiently stimulated reactivation of KSHV from latently infected PEL cells. We found that BET proteins BRD2 and BRD4 localize to several regions of the viral genome, including the LANA binding sites within the terminal repeats (TR), as well as at CTCF-cohesin sites in the latent and lytic control regions. JQ1 did not disrupt the interaction of BRD4 or BRD2 with LANA, but did reduce the binding of LANA with KSHV TR. We have previously demonstrated a cohesin-dependent DNA-loop interaction between the latent and lytic control regions that restrict expression of ORF50/RTA and ORF45 immediate early gene transcripts. JQ1 reduced binding of cohesin subunit Rad21 with the CTCF binding sites in the latency and lytic control regions. JQ1 also reduced DNA-loop interaction between latent and lytic control regions. These findings implicate BET proteins BRD2 and BRD4 in the maintenance of KSHV chromatin architecture during latency and reveal BET inhibitors as potent activators of KSHV reactivation from latency.
authors.affiliation: The Wistar Institute, Philadelphia, PA, United States of America.
authors.forename: Horng-Shen
authors.initials: HS
authors.lastname: Chen
authors.affiliation: The Wistar Institute, Philadelphia, PA, United States of America.
authors.forename: Alessandra
authors.initials: A
authors.lastname: De Leo
authors.affiliation: The Wistar Institute, Philadelphia, PA, United States of America.
authors.forename: Zhuo
authors.identifier: 0000-0002-8218-6819
authors.initials: Z
authors.lastname: Wang
authors.affiliation: The Wistar Institute, Philadelphia, PA, United States of America.
authors.forename: Andrew
authors.initials: A
authors.lastname: Kerekovic
authors.affiliation: The Wistar Institute, Philadelphia, PA, United States of America.
authors.forename: Robert
authors.initials: R
authors.lastname: Hills
authors.affiliation: The Wistar Institute, Philadelphia, PA, United States of America.
authors.forename: Paul M
authors.identifier: 0000-0002-3935-9921
authors.initials: PM
authors.lastname: Lieberman
mesh_terms: D000956:Antigens, Viral / Q000235:genetics / Q000378:metabolism; D001381:Azepines / Q000494:pharmacology*; D001402:B-Lymphocytes / Q000821:virology; D001665:Binding Sites / Q000187:drug effects; D018797:Cell Cycle Proteins; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins; D015967:Gene Expression Regulation, Viral; D057809:HEK293 Cells; D019288:Herpesvirus 8, Human / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*; D006801:Humans; D017874:Immediate-Early Proteins / Q000096:biosynthesis / Q000235:genetics; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D016066:Pleural Effusion, Malignant / Q000821:virology; D011485:Protein Binding / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering; D012514:Sarcoma, Kaposi / Q000821:virology; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014230:Triazoles / Q000494:pharmacology*; D014775:Virus Activation / Q000187:drug effects; D017735:Virus Latency / Q000187:drug effects*; D000092468:Bromodomain Containing Proteins
chemical_list: D000956:Antigens, Viral; D001381:Azepines; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D017874:Immediate-Early Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D017346:Protein Serine-Threonine Kinases; D034741:RNA, Small Interfering; D015534:Trans-Activators; D014157:Transcription Factors; D014230:Triazoles; C561695:(+)-JQ1 compound; C098415:BRD2 protein, human; D000092468:Bromodomain Containing Proteins; C441289:BRD4 protein, human; C456286:ORF45 protein, Kaposi's sarcoma-associated herpesvirus; C429022:RAD21 protein, human; C417604:Rta protein, Human herpesvirus 8; C109540:latency-associated nuclear antigen