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Olson AT, Kang Y, Ladha AM, Zhu S, Lim CB, Nabet B, Lagunoff M, Gujral TS, Geballe AP. Polypharmacology-based kinome screen identifies new regulators of KSHV reactivation. PLoS Pathog 2023; 19:e1011169. [PMID: 37669313 PMCID: PMC10503724 DOI: 10.1371/journal.ppat.1011169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 09/15/2023] [Accepted: 08/16/2023] [Indexed: 09/07/2023] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) causes several human diseases including Kaposi's sarcoma (KS), a leading cause of cancer in Africa and in patients with AIDS. KS tumor cells harbor KSHV predominantly in a latent form, while typically <5% contain lytic replicating virus. Because both latent and lytic stages likely contribute to cancer initiation and progression, continued dissection of host regulators of this biological switch will provide insights into fundamental pathways controlling the KSHV life cycle and related disease pathogenesis. Several cellular protein kinases have been reported to promote or restrict KSHV reactivation, but our knowledge of these signaling mediators and pathways is incomplete. We employed a polypharmacology-based kinome screen to identify specific kinases that regulate KSHV reactivation. Those identified by the screen and validated by knockdown experiments included several kinases that enhance lytic reactivation: ERBB2 (HER2 or neu), ERBB3 (HER3), ERBB4 (HER4), MKNK2 (MNK2), ITK, TEC, and DSTYK (RIPK5). Conversely, ERBB1 (EGFR1 or HER1), MKNK1 (MNK1) and FRK (PTK5) were found to promote the maintenance of latency. Mechanistic characterization of ERBB2 pro-lytic functions revealed a signaling connection between ERBB2 and the activation of CREB1, a transcription factor that drives KSHV lytic gene expression. These studies provided a proof-of-principle application of a polypharmacology-based kinome screen for the study of KSHV reactivation and enabled the discovery of both kinase inhibitors and specific kinases that regulate the KSHV latent-to-lytic replication switch.
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Affiliation(s)
- Annabel T. Olson
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
| | - Yuqi Kang
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
| | - Anushka M. Ladha
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Songli Zhu
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
| | - Chuan Bian Lim
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
| | - Behnam Nabet
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
| | - Michael Lagunoff
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Taranjit S. Gujral
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
| | - Adam P. Geballe
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
- Division of Clinical Research, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
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2
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Chappell DL, Sandhu PK, Wong JP, Bhatt AP, Liu X, Buhrlage SJ, Temple BRS, Major MB, Damania B. KSHV Viral Protein Kinase Interacts with USP9X to Modulate the Viral Lifecycle. J Virol 2023; 97:e0176322. [PMID: 36995092 PMCID: PMC10062123 DOI: 10.1128/jvi.01763-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 02/07/2023] [Indexed: 03/08/2023] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiological agent of Kaposi sarcoma (KS), the plasmablastic form of multicentric Castleman's disease, and primary effusion lymphoma. In sub-Saharan Africa, KS is the most common HIV-related malignancy and one of the most common childhood cancers. Immunosuppressed patients, including HIV-infected patients, are more prone to KSHV-associated disease. KSHV encodes a viral protein kinase (vPK) that is expressed from ORF36. KSHV vPK contributes to the optimal production of infectious viral progeny and upregulation of protein synthesis. To elucidate the interactions of vPK with cellular proteins in KSHV-infected cells, we used a bottom-up proteomics approach and identified host protein ubiquitin-specific peptidase 9X-linked (USP9X) as a potential interactor of vPK. Subsequently, we validated this interaction using a co-immunoprecipitation assay. We report that both the ubiquitin-like and the catalytic domains of USP9X are important for association with vPK. To uncover the biological relevance of the USP9X/vPK interaction, we investigated whether the knockdown of USP9X would modulate viral reactivation. Our data suggest that depletion of USP9X inhibits both viral reactivation and the production of infectious virions. Understanding how USP9X influences the reactivation of KSHV will provide insights into how cellular deubiquitinases regulate viral kinase activity and how viruses co-opt cellular deubiquitinases to propagate infection. Hence, characterizing the roles of USP9X and vPK during KSHV infection constitutes a first step toward identifying a potentially critical interaction that could be targeted by future therapeutics. IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiological agent of Kaposi sarcoma (KS), the plasmablastic form of multicentric Castleman's disease, and primary effusion lymphoma. In sub-Saharan Africa, KS is the most common HIV-related malignancy. KSHV encodes a viral protein kinase (vPK) that aids viral replication. To elucidate the interactions of vPK with cellular proteins in KSHV-infected cells, we used an affinity purification approach and identified host protein ubiquitin-specific peptidase 9X-linked (USP9X) as a potential interactor of vPK. Depletion of USP9X inhibits both viral reactivation and the production of infectious virions. Overall, our data suggest a proviral role for USP9X.
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Affiliation(s)
- Danielle L. Chappell
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Praneet K. Sandhu
- Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jason P. Wong
- Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Aadra P. Bhatt
- Department of Medicine, Division of Gastroenterology and Hepatology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Xiaoxi Liu
- Department of Cancer Biology and the Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Sara J. Buhrlage
- Department of Cancer Biology and the Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Brenda R. S. Temple
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- R. L. Juliano Structural Bioinformatics Core Facility, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Center for Structural Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - M. Ben Major
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Cell and Developmental Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Blossom Damania
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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3
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Lari A, Glaunsinger BA. Murine Gammaherpesvirus 68 ORF45 Stimulates B2 Retrotransposon and Pre-tRNA Activation in a Manner Dependent on Mitogen-Activated Protein Kinase (MAPK) Signaling. Microbiol Spectr 2023; 11:e0017223. [PMID: 36752632 PMCID: PMC10100704 DOI: 10.1128/spectrum.00172-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 01/21/2023] [Indexed: 02/09/2023] Open
Abstract
RNA polymerase III (RNAPIII) transcribes a variety of noncoding RNAs, including tRNA (tRNA) and the B2 family of short interspersed nuclear elements (SINEs). B2 SINEs are noncoding retrotransposons that possess tRNA-like promoters and are normally silenced in healthy somatic tissue. Infection with the murine gammaherpesvirus MHV68 induces transcription of both SINEs and tRNAs, in part through the activity of the viral protein kinase ORF36. Here, we identify the conserved MHV68 tegument protein ORF45 as an additional activator of these RNAPIII loci. MHV68 ORF45 and ORF36 form a complex, resulting in an additive induction RNAPIII and increased ORF45 expression. ORF45-induced RNAPIII transcription is dependent on its activation of the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) signaling pathway, which in turn increases the abundance of the RNAPIII transcription factor Brf1. Other viral and nonviral activators of MAPK/ERK signaling also increase the levels of Brf1 protein, B2 SINE RNA, and tRNA, suggesting that this is a common strategy to increase RNAPIII activity. IMPORTANCE Gammaherpesviral infection alters the gene expression landscape of a host cell, including through the induction of noncoding RNAs transcribed by RNA polymerase III (RNAPIII). Among these are a class of repetitive genes known as retrotransposons, which are normally silenced elements and can copy and spread throughout the genome, and transfer RNAs (tRNAs), which are fundamental components of protein translation machinery. How these loci are activated during infection is not well understood. Here, we identify ORF45 from the model murine gammaherpesvirus MHV68 as a novel activator of RNAPIII transcription. To do so, it engages the MAPK/ERK signaling pathway, which is a central regulator of cellular response to environmental stimuli. Activation of this pathway leads to the upregulation of a key factor required for RNAPIII activity, Brf1. These findings expand our understanding of the regulation and dysregulation of RNAPIII transcription and highlight how viral cooption of key signaling pathways can impact host gene expression.
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Affiliation(s)
- Azra Lari
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, USA
| | - Britt A. Glaunsinger
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
- Howard Hughes Medical Institute, Berkeley, California, USA
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Olson AT, Kang Y, Ladha AM, Lim CB, Lagunoff M, Gujral TS, Geballe AP. Polypharmacology-based kinome screen identifies new regulators of KSHV reactivation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.01.526589. [PMID: 36778430 PMCID: PMC9915688 DOI: 10.1101/2023.02.01.526589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) causes several human diseases including Kaposi's sarcoma (KS), a leading cause of cancer in Africa and in patients with AIDS. KS tumor cells harbor KSHV predominantly in a latent form, while typically <5% contain lytic replicating virus. Because both latent and lytic stages likely contribute to cancer initiation and progression, continued dissection of host regulators of this biological switch will provide insights into fundamental pathways controlling the KSHV life cycle and related disease pathogenesis. Several cellular protein kinases have been reported to promote or restrict KSHV reactivation, but our knowledge of these signaling mediators and pathways is incomplete. We employed a polypharmacology-based kinome screen to identifiy specific kinases that regulate KSHV reactivation. Those identified by the screen and validated by knockdown experiments included several kinases that enhance lytic reactivation: ERBB2 (HER2 or neu ), ERBB3 (HER3), ERBB4 (HER4), MKNK2 (MNK2), ITK, TEC, and DSTYK (RIPK5). Conversely, ERBB1 (EGFR1 or HER1), MKNK1 (MNK1) and FRK (PTK5) were found to promote the maintenance of latency. Mechanistic characterization of ERBB2 pro-lytic functions revealed a signaling connection between ERBB2 and the activation of CREB1, a transcription factor that drives KSHV lytic gene expression. These studies provided a proof-of-principle application of a polypharmacology-based kinome screen for the study of KSHV reactivation and enabled the discovery of both kinase inhibitors and specific kinases that regulate the KSHV latent-to-lytic replication switch. Author Summary Kaposi's sarcoma-associated herpesvirus (KSHV) causes Kaposi's sarcoma, a cancer particularly prevalent in Africa. In cancer cells, the virus persists in a quiescent form called latency, in which only a few viral genes are made. Periodically, the virus switches into an active replicative cycle in which most of the viral genes are made and new virus is produced. What controls the switch from latency to active replication is not well understood, but cellular kinases, enzymes that control many cellular processes, have been implicated. Using a cell culture model of KSHV reactivation along with an innovative screening method that probes the effects of many cellular kinases simultaneously, we identified drugs that significantly limit KSHV reactivation, as well as specific kinases that either enhance or restrict KSHV replicative cycle. Among these were the ERBB kinases which are known to regulate growth of cancer cells. Understanding how these and other kinases contribute to the switch leading to production of more infectious virus helps us understand the mediators and mechanisms of KSHV diseases. Additionally, because kinase inhibitors are proving to be effective for treating other diseases including some cancers, identifying ones that restrict KSHV replicative cycle may lead to new approaches to treating KSHV-related diseases.
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Affiliation(s)
- Annabel T. Olson
- Division of Human Biology, Fred Hutchinson Cancer Center, University of Washington, Seattle, WA, USA
| | - Yuqi Kang
- Division of Human Biology, Fred Hutchinson Cancer Center, University of Washington, Seattle, WA, USA
| | - Anushka M. Ladha
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | - Chuan Bian Lim
- Division of Human Biology, Fred Hutchinson Cancer Center, University of Washington, Seattle, WA, USA
| | - Michael Lagunoff
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | - Taran S. Gujral
- Division of Human Biology, Fred Hutchinson Cancer Center, University of Washington, Seattle, WA, USA
- Department of Pharmacology, University of Washington, Seattle, WA, USA
| | - Adam P. Geballe
- Division of Human Biology, Fred Hutchinson Cancer Center, University of Washington, Seattle, WA, USA
- Division of Clinical Research, Fred Hutchinson Cancer Center, University of Washington, Seattle, WA, USA
- Department of Microbiology, University of Washington, Seattle, WA, USA
- Department of Medicine, University of Washington, Seattle, WA, USA
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5
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Better late than never: A unique strategy for late gene transcription in the beta- and gammaherpesviruses. Semin Cell Dev Biol 2022; 146:57-69. [PMID: 36535877 PMCID: PMC10101908 DOI: 10.1016/j.semcdb.2022.12.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 12/01/2022] [Accepted: 12/01/2022] [Indexed: 12/23/2022]
Abstract
During lytic replication, herpesviruses express their genes in a temporal cascade culminating in expression of "late" genes. Two subfamilies of herpesviruses, the beta- and gammaherpesviruses (including human herpesviruses cytomegalovirus, Epstein-Barr virus, and Kaposi's sarcoma-associated herpesvirus), use a unique strategy to facilitate transcription of late genes. They encode six essential viral transcriptional activators (vTAs) that form a complex at a subset of late gene promoters. One of these vTAs is a viral mimic of host TATA-binding protein (vTBP) that recognizes a strikingly minimal cis-acting element consisting of a modified TATA box with a TATTWAA consensus sequence. vTBP is also responsible for recruitment of cellular RNA polymerase II (Pol II). Despite extensive work in the beta/gammaherpesviruses, the function of the other five vTAs remains largely unknown. The vTA complex and Pol II assemble on the promoter into a viral preinitiation complex (vPIC) to facilitate late gene transcription. Here, we review the properties of the vTAs and the promoters on which they act.
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Zhou L, Cheng A, Wang M, Wu Y, Yang Q, Tian B, Ou X, Sun D, Zhang S, Mao S, Zhao XX, Huang J, Gao Q, Zhu D, Jia R, Liu M, Chen S. Mechanism of herpesvirus protein kinase UL13 in immune escape and viral replication. Front Immunol 2022; 13:1088690. [PMID: 36531988 PMCID: PMC9749954 DOI: 10.3389/fimmu.2022.1088690] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 11/15/2022] [Indexed: 12/05/2022] Open
Abstract
Upon infection, the herpes viruses create a cellular environment suitable for survival, but innate immunity plays a vital role in cellular resistance to viral infection. The UL13 protein of herpesviruses is conserved among all herpesviruses and is a serine/threonine protein kinase, which plays a vital role in escaping innate immunity and promoting viral replication. On the one hand, it can target various immune signaling pathways in vivo, such as the cGAS-STING pathway and the NF-κB pathway. On the other hand, it phosphorylates regulatory many cellular and viral proteins for promoting the lytic cycle. This paper reviews the research progress of the conserved herpesvirus protein kinase UL13 in immune escape and viral replication to provide a basis for elucidating the pathogenic mechanism of herpesviruses, as well as providing insights into the potential means of immune escape and viral replication of other herpesviruses that have not yet resolved the function of it.
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Affiliation(s)
- Lin Zhou
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Anchun Cheng
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Mingshu Wang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,*Correspondence: Mingshu Wang,
| | - Ying Wu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Qiao Yang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Bin Tian
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Xumin Ou
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Di Sun
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Shaqiu Zhang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Sai Mao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Xin-Xin Zhao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Juan Huang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Qun Gao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Dekang Zhu
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Renyong Jia
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Mafeng Liu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Shun Chen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
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7
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The Interaction between Tegument Proteins ORF33 and ORF45 Plays an Essential Role in Cytoplasmic Virion Maturation of a Gammaherpesvirus. J Virol 2022; 96:e0107322. [PMID: 36300940 PMCID: PMC9683023 DOI: 10.1128/jvi.01073-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A critical step in viral lytic replication is the assembly of progeny viral particles. Herpesviruses are important pathogens.
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8
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The ORF45 Protein of Kaposi's Sarcoma-Associated Herpesvirus and Its Critical Role in the Viral Life Cycle. Viruses 2022; 14:v14092010. [PMID: 36146816 PMCID: PMC9506158 DOI: 10.3390/v14092010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 09/07/2022] [Accepted: 09/07/2022] [Indexed: 11/17/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) protein ORF45 is a virion-associated tegument protein that is unique to the gammaherpesvirus family. Generation of KSHV ORF45-knockout mutants and their subsequent functional analyses have permitted a better understanding of ORF45 and its context-specific and vital role in the KSHV lytic cycle. ORF45 is a multifaceted protein that promotes infection at both the early and late phases of the viral life cycle. As an immediate-early protein, ORF45 is expressed within hours of KSHV lytic reactivation and plays an essential role in promoting the lytic cycle, using multiple mechanisms, including inhibition of the host interferon response. As a tegument protein, ORF45 is necessary for the proper targeting of the viral capsid for envelopment and release, affecting the late stage of the viral life cycle. A growing list of ORF45 interaction partners have been identified, with one of the most well-characterized being the association of ORF45 with the host extracellular-regulated kinase (ERK) p90 ribosomal s6 kinase (RSK) signaling cascade. In this review, we describe ORF45 expression kinetics, as well as the host and viral interaction partners of ORF45 and the significance of these interactions in KSHV biology. Finally, we discuss the role of ORF45 homologs in gammaherpesvirus infections.
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9
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Alexa A, Sok P, Gross F, Albert K, Kobori E, Póti ÁL, Gógl G, Bento I, Kuang E, Taylor SS, Zhu F, Ciliberto A, Reményi A. A non-catalytic herpesviral protein reconfigures ERK-RSK signaling by targeting kinase docking systems in the host. Nat Commun 2022; 13:472. [PMID: 35078976 PMCID: PMC8789800 DOI: 10.1038/s41467-022-28109-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 01/07/2022] [Indexed: 12/16/2022] Open
Abstract
The Kaposi's sarcoma associated herpesvirus protein ORF45 binds the extracellular signal-regulated kinase (ERK) and the p90 Ribosomal S6 kinase (RSK). ORF45 was shown to be a kinase activator in cells but a kinase inhibitor in vitro, and its effects on the ERK-RSK complex are unknown. Here, we demonstrate that ORF45 binds ERK and RSK using optimized linear binding motifs. The crystal structure of the ORF45-ERK2 complex shows how kinase docking motifs recognize the activated form of ERK. The crystal structure of the ORF45-RSK2 complex reveals an AGC kinase docking system, for which we provide evidence that it is functional in the host. We find that ORF45 manipulates ERK-RSK signaling by favoring the formation of a complex, in which activated kinases are better protected from phosphatases and docking motif-independent RSK substrate phosphorylation is selectively up-regulated. As such, our data suggest that ORF45 interferes with the natural design of kinase docking systems in the host.
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Affiliation(s)
- Anita Alexa
- Biomolecular Interactions Research Group, Institute of Organic Chemistry, Research Center for Natural Sciences, H-1117, Budapest, Hungary
| | - Péter Sok
- Biomolecular Interactions Research Group, Institute of Organic Chemistry, Research Center for Natural Sciences, H-1117, Budapest, Hungary
| | - Fridolin Gross
- IFOM, Istituto FIRC di Oncologia Molecolare, 20139, Milan, Italy
| | - Krisztián Albert
- Biomolecular Interactions Research Group, Institute of Organic Chemistry, Research Center for Natural Sciences, H-1117, Budapest, Hungary
| | - Evan Kobori
- Department of Chemistry and Biochemistry, University of California San Diego, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0654, USA
| | - Ádám L Póti
- Biomolecular Interactions Research Group, Institute of Organic Chemistry, Research Center for Natural Sciences, H-1117, Budapest, Hungary
| | - Gergő Gógl
- Biomolecular Interactions Research Group, Institute of Organic Chemistry, Research Center for Natural Sciences, H-1117, Budapest, Hungary
| | - Isabel Bento
- European Molecular Biology Laboratory, Hamburg, Germany
| | - Ersheng Kuang
- Department of Biological Science, Florida State University, Tallahassee, FL, 32306-4370, USA
| | - Susan S Taylor
- Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, La Jolla, San Diego, CA, 92093-0654, USA
| | - Fanxiu Zhu
- Department of Biological Science, Florida State University, Tallahassee, FL, 32306-4370, USA
| | - Andrea Ciliberto
- IFOM, Istituto FIRC di Oncologia Molecolare, 20139, Milan, Italy
| | - Attila Reményi
- Biomolecular Interactions Research Group, Institute of Organic Chemistry, Research Center for Natural Sciences, H-1117, Budapest, Hungary.
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10
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Gillen J, Zhu F. Disruption of the Interaction between ORF33 and the Conserved Carboxyl-Terminus of ORF45 Abolishes Progeny Virion Production of Kaposi Sarcoma-Associated Herpesvirus. Viruses 2021; 13:1828. [PMID: 34578410 PMCID: PMC8472245 DOI: 10.3390/v13091828] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/09/2021] [Accepted: 09/10/2021] [Indexed: 12/12/2022] Open
Abstract
The Open Reading Frame 45 (ORF45) of Kaposi sarcoma-associated herpesvirus (KSHV) is a gammaherpesvirus-specific, immediate-early, tegument protein required for efficient viral replication and virion production. We have previously shown that ORF45 interacts with the conserved herpesviral protein ORF33 through the highly conserved C-terminal 19 amino acids (C19) of ORF45. Because the deletion of C19 abolished ORF33 accumulation and viral production, we reasoned that this interaction could be critical for viral production and explored as an antiviral target for gammaherpesviruses. In work described in this article, we characterize this interaction in further detail, first by revealing that this interaction is conserved among gammaherpesviruses, then by identifying residues in C19 critical for its interaction with and stabilization of ORF33. More importantly, we show that disruption of the interaction, either by mutating key residues (W403A or W405A) in C19 or by using competing cell penetration peptide TAT-C19, dramatically reduce the yield of KSHV progeny viruses. Our results not only reveal critical roles of this interaction to viral production but also provide a proof of concept for targeting the ORF33-ORF45 interaction as a novel antiviral strategy against KSHV and other gammaherpesviruses.
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Affiliation(s)
- Joseph Gillen
- Functional Cellular Networks Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-1892, USA;
| | - Fanxiu Zhu
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370, USA
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11
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Guo F, Xing L. RNA helicase A as co-factor for DNA viruses during replication. Virus Res 2020; 291:198206. [PMID: 33132162 DOI: 10.1016/j.virusres.2020.198206] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 10/17/2020] [Accepted: 10/19/2020] [Indexed: 11/30/2022]
Abstract
RNA helicase A (RHA) is a ubiquitously expressed DExH-box helicase enzyme that is involved in a wide range of biological processes including transcription, translation, and RNA processing. A number of RNA viruses recruit RHA to the viral RNA to facilitate virus replication. DNA viruses contain a DNA genome and replicate using a DNA-dependent DNA polymerase. RHA has also been reported to associate with some DNA viruses during replication, in which the enzyme acts on the viral RNA or protein products. As shown for Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus, RHA has potential to allow the virus to control a switch in cellular gene expression to modulate the antiviral response. While the study of the interaction of RHA with DNA viruses is still at an early stage, preliminary evidence indicates that the underlying molecular mechanisms are diverse. We now review the current status of this emerging field.
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Affiliation(s)
- Fan Guo
- Institute of Biomedical Sciences, Shanxi University, 92 Wucheng Road, Taiyuan 030006, Shanxi province, PR China
| | - Li Xing
- Institute of Biomedical Sciences, Shanxi University, 92 Wucheng Road, Taiyuan 030006, Shanxi province, PR China.
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12
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Cross-regulation of viral kinases with cyclin A secures shutoff of host DNA synthesis. Nat Commun 2020; 11:4845. [PMID: 32973148 PMCID: PMC7518283 DOI: 10.1038/s41467-020-18542-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 08/24/2020] [Indexed: 12/25/2022] Open
Abstract
Herpesviruses encode conserved protein kinases (CHPKs) to stimulate phosphorylation-sensitive processes during infection. How CHPKs bind to cellular factors and how this impacts their regulatory functions is poorly understood. Here, we use quantitative proteomics to determine cellular interaction partners of human herpesvirus (HHV) CHPKs. We find that CHPKs can target key regulators of transcription and replication. The interaction with Cyclin A and associated factors is identified as a signature of β-herpesvirus kinases. Cyclin A is recruited via RXL motifs that overlap with nuclear localization signals (NLS) in the non-catalytic N termini. This architecture is conserved in HHV6, HHV7 and rodent cytomegaloviruses. Cyclin A binding competes with NLS function, enabling dynamic changes in CHPK localization and substrate phosphorylation. The cytomegalovirus kinase M97 sequesters Cyclin A in the cytosol, which is essential for viral inhibition of cellular replication. Our data highlight a fine-tuned and physiologically important interplay between a cellular cyclin and viral kinases.
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13
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The Interaction between ORF18 and ORF30 Is Required for Late Gene Expression in Kaposi's Sarcoma-Associated Herpesvirus. J Virol 2018; 93:JVI.01488-18. [PMID: 30305361 DOI: 10.1128/jvi.01488-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 10/05/2018] [Indexed: 01/04/2023] Open
Abstract
In the beta- and gammaherpesviruses, a specialized complex of viral transcriptional activators (vTAs) coordinate to direct expression of virus-encoded late genes, which are critical for viral assembly and whose transcription initiates only after the onset of viral DNA replication. The vTAs in Kaposi's sarcoma-associated herpesvirus (KSHV) are ORF18, ORF24, ORF30, ORF31, ORF34, and ORF66. While the general organization of the vTA complex has been mapped, the individual roles of these proteins and how they coordinate to activate late gene promoters remain largely unknown. Here, we performed a comprehensive mutational analysis of the conserved residues in ORF18, which is a highly interconnected vTA component. Surprisingly, the mutants were largely selective for disrupting the interaction with ORF30 but not the other three ORF18 binding partners. Furthermore, disrupting the ORF18-ORF30 interaction weakened the vTA complex as a whole, and an ORF18 point mutant that failed to bind ORF30 was unable to complement an ORF18 null virus. Thus, contacts between individual vTAs are critical as even small disruptions in this complex result in profound defects in KSHV late gene expression.IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent of Kaposi's sarcoma and other B-cell cancers and remains a leading cause of death in immunocompromised individuals. A key step in the production of infectious virions is the transcription of viral late genes, which generates capsid and structural proteins and requires the coordination of six viral proteins that form a complex. The role of these proteins during transcription complex formation and the importance of protein-protein interactions are not well understood. Here, we focused on a central component of the complex, ORF18, and revealed that disruption of its interaction with even a single component of the complex (ORF30) prevents late gene expression and completion of the viral lifecycle. These findings underscore how individual interactions between the late gene transcription components are critical for both the stability and function of the complex.
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14
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Cha S, Kang MS, Seo T. KSHV vPK inhibits Wnt signaling via preventing interactions between β-catenin and TCF4. Biochem Biophys Res Commun 2018; 497:381-387. [PMID: 29432739 DOI: 10.1016/j.bbrc.2018.02.089] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Accepted: 02/08/2018] [Indexed: 01/15/2023]
Abstract
Viral factors interact with host cellular proteins, leading to dysregulation of signaling pathways. The Wnt pathway is known to participate in embryonic development and oncogenesis under dysregulation conditions. A downstream factor of the Wnt signaling pathway, β-catenin, activates T-cell factor (TCF)-dependent transcription, which contributes to cell proliferation and tumorigenesis. In this study, we demonstrated that viral protein kinase (vPK) encoded by Kaposi's sarcoma-associated herpesvirus inhibits the Wnt signaling pathway without affecting nuclear localization and expression of β-catenin. Coimmunoprecipitation and chromatin immunoprecipitation assays revealed that vPK interacts with β-catenin, reducing the binding affinity on TCF binding regions as well as interactions of β-catenin with TCF4. Overexpression of vPK led to reduced mRNA expression of cyclin D1, a well-known transcriptional product of Wnt signaling, suggesting that vPK effectively regulates the host signaling pathway through direct interactions with cellular proteins.
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Affiliation(s)
- Seho Cha
- Department of Life Science, Dongguk University-Seoul, Goyang, 10326, Republic of Korea
| | - Myung-Suk Kang
- National Institute of Biological Resources, 42 Hwangyeong-ro, Incheon 22689, Republic of Korea
| | - Taegun Seo
- Department of Life Science, Dongguk University-Seoul, Goyang, 10326, Republic of Korea.
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15
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Wang F, Guo Y, Li W, Lu C, Yan Q. Generation of a KSHV K13 deletion mutant for vFLIP function study. J Med Virol 2018; 90:753-760. [PMID: 29244209 DOI: 10.1002/jmv.25009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/27/2017] [Indexed: 01/11/2023]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV)-encoded viral Fas-associated death domain-like IL-1-converting enzyme inhibitory protein (vFLIP) is one of the latently expressed genes and plays a key role in cell survival and maintenance of latent infection by activating the NF-κB pathway. To obtain a genetic system for studying KSHV vFLIP mutation in the context of the viral genome, we generated recombinant viruses lacking the coding sequence (CDS) of vFLIP gene (K13/ORF71) by bacterial artificial chromosome (BAC) technology and the Escherichia coli Red recombination system. After a series of verification with PCR, restriction digestion and sequencing, the K13 deletion bacmids was transfected into a stable viral producer cell line based on iSLK cells to create vFLIP-knockout mutant. Importantly, human umbilical vein endothelial cells (HUVECs) could be de novo infected by vFLIP mutant virus, which are now available for studying the roles of vFLIP in regulation of other KSHV genes and viral pathogenesis.
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Affiliation(s)
- Fei Wang
- Key Laboratory of Pathogen Biology of Jiangsu Province, Nanjing Medical University, Nanjing, P. R. China.,Department of Microbiology, Nanjing Medical University, Nanjing, P. R. China
| | - Yuanyuan Guo
- School of Medicine and Life Sciences, Nanjing University of Chinese Medicine, Nanjing, P. R. China.,Jiangsu Collaborative Innovation Center of Traditional Chinese Medicine (TCM) Prevention and Treatment of Tumor, Nanjing University of Chinese Medicine, Nanjing, P. R. China
| | - Wan Li
- Key Laboratory of Pathogen Biology of Jiangsu Province, Nanjing Medical University, Nanjing, P. R. China.,Department of Microbiology, Nanjing Medical University, Nanjing, P. R. China
| | - Chun Lu
- Key Laboratory of Pathogen Biology of Jiangsu Province, Nanjing Medical University, Nanjing, P. R. China.,Department of Microbiology, Nanjing Medical University, Nanjing, P. R. China
| | - Qin Yan
- Key Laboratory of Pathogen Biology of Jiangsu Province, Nanjing Medical University, Nanjing, P. R. China.,Department of Microbiology, Nanjing Medical University, Nanjing, P. R. China
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16
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Epstein-Barr Virus BKRF4 Gene Product Is Required for Efficient Progeny Production. J Virol 2017; 91:JVI.00975-17. [PMID: 28904200 DOI: 10.1128/jvi.00975-17] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 09/08/2017] [Indexed: 12/14/2022] Open
Abstract
Epstein-Barr virus (EBV), a member of human gammaherpesvirus, infects mainly B cells. EBV has two alternative life cycles, latent and lytic, and is reactivated occasionally from the latent stage to the lytic cycle. To combat EBV-associated disorders, understanding the molecular mechanisms of the EBV lytic replication cycle is also important. Here, we focused on an EBV lytic gene, BKRF4. Using our anti-BKRF4 antibody, we revealed that the BKRF4 gene product is expressed during the lytic cycle with late kinetics. To characterize the role of BKRF4, we constructed BKRF4-knockout mutants using the bacterial artificial chromosome (BAC) and CRISPR/Cas9 systems. Although disruption of the BKRF4 gene had almost no effect on viral protein expression and DNA synthesis, it significantly decreased progeny virion levels in HEK293 and Akata cells. Furthermore, we show that BKRF4 is involved not only in production of progeny virions but also in increasing the infectivity of the virus particles. Immunoprecipitation assays revealed that BKRF4 interacted with a virion protein, BGLF2. We showed that the C-terminal region of BKRF4 was critical for this interaction and for efficient progeny production. Immunofluorescence analysis revealed that BKRF4 partially colocalized with BGLF2 in the nucleus and perinuclear region. Finally, we showed that BKRF4 is a phosphorylated, possible tegument protein and that the EBV protein kinase BGLF4 may be important for this phosphorylation. Taken together, our data suggest that BKRF4 is involved in the production of infectious virions.IMPORTANCE Although the latent genes of EBV have been studied extensively, the lytic genes are less well characterized. This study focused on one such lytic gene, BKRF4, which is conserved only among gammaherpesviruses (ORF45 of Kaposi's sarcoma-associated herpesvirus or murine herpesvirus 68). After preparing the BKRF4 knockout virus using B95-8 EBV-BAC, we demonstrated that the BKRF4 gene was involved in infectious progeny particle production. Importantly, we successfully generated a BKRF4 knockout virus of Akata using CRISPR/Cas9 technology, confirming the phenotype in this separate strain. We further showed that BKRF4 interacted with another virion protein, BGLF2, and demonstrated the importance of this interaction in infectious virion production. These results shed light on the elusive process of EBV progeny maturation in the lytic cycle. Notably, this study describes a successful example of the generation and characterization of an EBV construct with a disrupted lytic gene using CRISPR/Cas9 technology.
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17
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KSHV inhibits stress granule formation by viral ORF57 blocking PKR activation. PLoS Pathog 2017; 13:e1006677. [PMID: 29084250 PMCID: PMC5679657 DOI: 10.1371/journal.ppat.1006677] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 11/09/2017] [Accepted: 10/03/2017] [Indexed: 11/18/2022] Open
Abstract
TIA-1 positive stress granules (SG) represent the storage sites of stalled mRNAs and are often associated with the cellular antiviral response. In this report, we provide evidence that Kaposi's sarcoma-associated herpesvirus (KSHV) overcomes the host antiviral response by inhibition of SG formation via a viral lytic protein ORF57. By immunofluorescence analysis, we found that B lymphocytes with KSHV lytic infection are refractory to SG induction. KSHV ORF57, an essential post-transcriptional regulator of viral gene expression and the production of new viral progeny, inhibits SG formation induced experimentally by arsenite and poly I:C, but not by heat stress. KSHV ORF37 (vSOX) bearing intrinsic endoribonuclease activity also inhibits arsenite-induced SG formation, but KSHV RTA, vIRF-2, ORF45, ORF59 and LANA exert no such function. ORF57 binds both PKR-activating protein (PACT) and protein kinase R (PKR) through their RNA-binding motifs and prevents PACT-PKR interaction in the PKR pathway which inhibits KSHV production. Consistently, knocking down PKR expression significantly promotes KSHV virion production. ORF57 interacts with PKR to inhibit PKR binding dsRNA and its autophosphorylation, leading to inhibition of eIF2α phosphorylation and SG formation. Homologous protein HSV-1 ICP27, but not EBV EB2, resembles KSHV ORF57 in the ability to block the PKR/eIF2α/SG pathway. In addition, KSHV ORF57 inhibits poly I:C-induced TLR3 phosphorylation. Altogether, our data provide the first evidence that KSHV ORF57 plays a role in modulating PKR/eIF2α/SG axis and enhances virus production during virus lytic infection.
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18
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ZIC2 Is Essential for Maintenance of Latency and Is a Target of an Immediate Early Protein during Kaposi's Sarcoma-Associated Herpesvirus Lytic Reactivation. J Virol 2017; 91:JVI.00980-17. [PMID: 28835494 PMCID: PMC5640855 DOI: 10.1128/jvi.00980-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 08/14/2017] [Indexed: 01/05/2023] Open
Abstract
Bivalent histone modifications are defined as repressive and activating epigenetic marks that simultaneously decorate the same genomic region. The H3K27me3 mark silences gene expression, while the H3K4me3 mark prevents the region from becoming permanently silenced and prepares the domain for activation when needed. Specific regions of Kaposi's sarcoma-associated herpesvirus (KSHV) latent episomes are poised to be activated by the KSHV replication and transcription activator (K-Rta). How KSHV episomes are prepared such that they maintain latent infection and switch to lytic replication by K-Rta remains unclear. K-Rta transactivation activity requires a protein degradation function; thus, we hypothesized that identification of cellular substrates of K-Rta may provide insight into the maintenance of KSHV latent infection and the switch to lytic replication. Here we show that a zinc finger protein, ZIC2, a key regulator for central nervous system development, is a substrate of K-Rta and is responsible for maintaining latency. K-Rta directly interacted with ZIC2 and functioned as an E3 ligase to ubiquitinate ZIC2. ZIC2 localized at immediate early and early gene cluster regions of the KSHV genome and contributed to tethering of polycomb repressive complex 2 through physical interaction, thus maintaining H3K27me3 marks at the K-Rta promoter. Accordingly, depletion of ZIC2 shifted the balance of bivalent histone modifications toward more active forms and induced KSHV reactivation in naturally infected cells. We suggest that ZIC2 turnover by K-Rta is a strategy employed by KSHV to favor the transition from latency to lytic replication. IMPORTANCE Posttranslational histone modifications regulate the accessibility of transcriptional factors to DNA; thus, they have profound effects on gene expression (e.g., viral reactivation). KSHV episomes are known to possess bivalent chromatin domains. How such KSHV chromatin domains are maintained to be reactivatable by K-Rta remains unclear. We found that ZIC2, a transcriptional factor essential for stem cell pluripotency, plays a role in maintaining KSHV latent infection in naturally infected cells. We found that ZIC2 degradation by K-Rta shifts bivalent histone marks to a more active configuration, leading to KSHV reactivation. ZIC2 interacts with and maintains polycomb repressor complex 2 at the K-Rta promoter. Our findings uncover (i) a mechanism utilized by KSHV to maintain latent infection, (ii) a latency-lytic cycle switch operated by K-Rta, and (iii) a molecular mechanism of ZIC2-mediated local histone modification.
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19
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Wong JP, Damania B. Modulation of oncogenic signaling networks by Kaposi's sarcoma-associated herpesvirus. Biol Chem 2017; 398:911-918. [PMID: 28284028 DOI: 10.1515/hsz-2017-0101] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 03/08/2017] [Indexed: 01/07/2023]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiological agent of three human malignancies: Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. To persist and replicate within host cells, KSHV encodes proteins that modulate different signaling pathways. Manipulation of cell survival and proliferative networks by KSHV can promote the development of KSHV-associated malignancies. In this review, we discuss recent updates on KSHV pathogenesis and the viral life cycle. We focus on proteins encoded by KSHV that modulate the phosphatidylinositol-4,5-bisphosphate 3 kinase and extracellular signal-regulated kinases 1/2 pathways to create an environment favorable for viral replication and the development of KSHV malignancies.
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20
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Watanabe T, Sakaida K, Yoshida M, Masud HMAA, Sato Y, Goshima F, Kimura H, Murata T. The C-Terminus of Epstein-Barr Virus BRRF2 Is Required for its Proper Localization and Efficient Virus Production. Front Microbiol 2017; 8:125. [PMID: 28197146 PMCID: PMC5281634 DOI: 10.3389/fmicb.2017.00125] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 01/18/2017] [Indexed: 02/02/2023] Open
Abstract
Epstein-Barr virus (EBV) is a human gammaherpesvirus associated with several malignancies. We reported previously that an EBV lytic gene product BRRF2 is involved in the maturation of progeny virus. To analyze the domain(s) needed for efficient production of progeny, we prepared a series of deletion mutants and found two functional domains in the N- and C-terminal regions by complementation assays. Immunofluorescence analyses revealed that BRRF2 lacking the C-terminal region demonstrated aberrant localization in both the nucleus and cytoplasm, whereas wild-type BRRF2 was localized predominantly in the cytoplasm. We also confirmed that wild-type BRRF2 co-localized with Rab5, an endosomal marker, at least partly. Additionally, serine 511 of BRRF2 was phosphorylated during lytic infection; however, a mutant in which the serine was substituted with alanine still augmented the yield as efficiently as did wild-type BRRF2. These results showed that the C-terminal region of BRRF2 is involved in the predominant localization of BRRF2 to the cytoplasm and in the efficient production of infectious virus.
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Affiliation(s)
- Takahiro Watanabe
- Department of Virology, Nagoya University Graduate School of Medicine Nagoya, Japan
| | - Keiya Sakaida
- Department of Virology, Nagoya University Graduate School of Medicine Nagoya, Japan
| | - Masahiro Yoshida
- Department of Virology, Nagoya University Graduate School of Medicine Nagoya, Japan
| | | | - Yoshitaka Sato
- Department of Virology, Nagoya University Graduate School of Medicine Nagoya, Japan
| | - Fumi Goshima
- Department of Virology, Nagoya University Graduate School of Medicine Nagoya, Japan
| | - Hiroshi Kimura
- Department of Virology, Nagoya University Graduate School of Medicine Nagoya, Japan
| | - Takayuki Murata
- Department of Virology, Nagoya University Graduate School of Medicine Nagoya, Japan
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