TY - JOUR
T1 - The SWI/SNF chromatin regulator BRG1 modulates the transcriptional regulatory activity of the Epstein-Barr virus DNA polymerase processivity factor BMRF1
AU - Su, Mei Tzu
AU - Wang, Ya Ting
AU - Chen, Yen Ju
AU - Lin, Su Fang
AU - Tsai, Ching Hwa
AU - Chen, Mei Ru
N1 - Funding Information:
We thank H. J. Delecluse (German Cancer Research Centre [DKFZ]) for the EBV bacmid p2089, PCR template plasmid PIJ773, and λ Red recombination plasmid. We thank the Center of Genomic Medicine, National Taiwan University, for the mass spectrometry analysis. We thank the Cell Imaging Core of the First Core Labs in the National Taiwan University College of Medicine for confocal image analysis. We thank Tzu-Lung Lin (National Taiwan University) and Chia-Wei Wu (Oak Ridge National Laboratory) for the microarray analysis. We are grateful to Tim J. Harrison of the University College London for critical reading and editing of the manuscript. This study was funded by the Ministry of Science and Technology, Taiwan (MOST) (NSC 101-2320-B-002-031-MY3 and MOST-104-2320-B-002-054-MY3) and partially supported by the National Health Research Institutes (NHRI) and National Taiwan University College of Medicine through grants NHRI-EX105-10201BI, 105C101-A2, and 106C101-F2. Mei-Tzu Su was supported by grants MOST-104-2811-B-002-115 and MOST-105-2811-B-002-085.
Publisher Copyright:
© 2017 American Society for Microbiology.
PY - 2017/5/1
Y1 - 2017/5/1
N2 - During the lytic phase of Epstein-Barr virus (EBV), binding of the transactivator Zta to the origin of lytic replication (oriLyt) and the BHLF1 transcript, forming a stable RNA-DNA hybrid, is required to initiate viral DNA replication. EBVencoded viral DNA replication proteins form complexes to amplify viral DNA. BMRF1, the viral DNA polymerase accessory factor, is essential for lytic DNA replication and also known as a transcriptional regulator of the expression of BHLF1 and BALF2 (single-stranded DNA [ssDNA]-binding protein). In order to determine systematically how BMRF1 regulates viral transcription, a BMRF1 knockout bacmid was generated to analyze viral gene expression using a viral DNA microarray. We found that a subset of Rta-responsive late genes, including BcLF1, BLLF1, BLLF2, and BDLF3, were downregulated in cells harboring a BMRF1 knockout EBV bacmid (p2089ΔBMRF1). In reporter assays, BMRF1 appears to transactivate a subset of viral late promoters through distinct pathways. BMRF1 activates the BDLF3 promoter in an SP1-dependent manner. Notably, BMRF1 associates with the transcriptional regulator BRG1 in EBV-reactivated cells. BMRF1-mediated transactivation activities on the BcLF1 and BLLF1 promoters were attenuated by knockdown of BRG1. In BRG1-depleted EBV-reactivated cells, BcLF1 and BLLF1 transcripts were reduced in number, resulting in reduced virion secretion. BMRF1 and BRG1 bound to the adjacent upstream regions of the BcLF1 and BLLF1 promoters, and depletion of BRG1 attenuated the recruitment of BMRF1 onto both promoters, suggesting that BRG1 is involved in BMRF1-mediated regulation of these two genes. Overall, we reveal a novel pathway by which BMRF1 can regulate viral promoters through interaction with BRG1.
AB - During the lytic phase of Epstein-Barr virus (EBV), binding of the transactivator Zta to the origin of lytic replication (oriLyt) and the BHLF1 transcript, forming a stable RNA-DNA hybrid, is required to initiate viral DNA replication. EBVencoded viral DNA replication proteins form complexes to amplify viral DNA. BMRF1, the viral DNA polymerase accessory factor, is essential for lytic DNA replication and also known as a transcriptional regulator of the expression of BHLF1 and BALF2 (single-stranded DNA [ssDNA]-binding protein). In order to determine systematically how BMRF1 regulates viral transcription, a BMRF1 knockout bacmid was generated to analyze viral gene expression using a viral DNA microarray. We found that a subset of Rta-responsive late genes, including BcLF1, BLLF1, BLLF2, and BDLF3, were downregulated in cells harboring a BMRF1 knockout EBV bacmid (p2089ΔBMRF1). In reporter assays, BMRF1 appears to transactivate a subset of viral late promoters through distinct pathways. BMRF1 activates the BDLF3 promoter in an SP1-dependent manner. Notably, BMRF1 associates with the transcriptional regulator BRG1 in EBV-reactivated cells. BMRF1-mediated transactivation activities on the BcLF1 and BLLF1 promoters were attenuated by knockdown of BRG1. In BRG1-depleted EBV-reactivated cells, BcLF1 and BLLF1 transcripts were reduced in number, resulting in reduced virion secretion. BMRF1 and BRG1 bound to the adjacent upstream regions of the BcLF1 and BLLF1 promoters, and depletion of BRG1 attenuated the recruitment of BMRF1 onto both promoters, suggesting that BRG1 is involved in BMRF1-mediated regulation of these two genes. Overall, we reveal a novel pathway by which BMRF1 can regulate viral promoters through interaction with BRG1.
KW - BMRF1
KW - BRG1
KW - Chromatin regulator
KW - DNA polymerase accessory factor
KW - Epstein-Barr virus
KW - Transcriptional regulation
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U2 - 10.1128/JVI.02114-16
DO - 10.1128/JVI.02114-16
M3 - Article
C2 - 28228591
AN - SCOPUS:85017527300
VL - 91
JO - Journal of Virology
JF - Journal of Virology
SN - 0022-538X
IS - 9
M1 - e02114-16
ER -