Chronic hepatitis B is perpetuated by the presence of covalently closed circular DNA(cccDNA)from the hepatitis B virus(HBV)in the liver’s hepatocytes.Despite these efforts,the exact mechanisms by which the chromatin ...Chronic hepatitis B is perpetuated by the presence of covalently closed circular DNA(cccDNA)from the hepatitis B virus(HBV)in the liver’s hepatocytes.Despite these efforts,the exact mechanisms by which the chromatin structure of cccDNA enables viral persistence remain unclear.This study investigates the vital role of mammalian SWI/SNF chromatin remodeling complexes in regulating the transcriptional activity of cccDNA.Our research,using pharmacological inhibitors and genetic techniques,identifies BRG1(SMARCA4),the central ATPase of the mSWI/SNF complexes,and BRD9,a non-canonical BAF(ncBAF)-specific subunit,as crucial host factors for HBV replication.The overexpression of SMARCA4 enhances viral propagation,whereas its targeted degradation using PROTAC AU15330 or siRNA significantly reduces cccDNA-driven transcription,viral transcripts,and protein levels.Chromatin accessibility assays demonstrate that the depletion of BRG1(SMARCA4)compacts the chromatin at critical cccDNA regulatory regions.Mechanistically,the HBV X protein(HBx)interacts with BAF155 and collaborates with transcription factor YY1 to promote the SWI/SNF complex binding to viral chromatin.Interestingly,inhibiting BRD9,an ncBAF-specific acetyl-lysine reader,similarly disrupts cccDNA transcription,indicating a coordinated function of canonical and non-canonical SWI/SNF complexes via acetylation-dependent chromatin remodeling.These insights highlight SWI/SNF complexes as key regulators of viral persistence and suggest targeting these complexes as a potential therapeutic strategy for eradicating cccDNA reservoirs,potentially leading to a functional cure for chronic HBV infection.展开更多
Switch defective/sucrose non-fermentable(SWI/SNF)chromatin remodeling complexes are multi-subunit machines that play vital roles in the regulation of chromatin structure and gene expression.However,the mechanisms by w...Switch defective/sucrose non-fermentable(SWI/SNF)chromatin remodeling complexes are multi-subunit machines that play vital roles in the regulation of chromatin structure and gene expression.However,the mechanisms by which SWI/SNF complexes recognize their target loci in plants are not fully understood.Here,we show that the Arabidopsis thaliana bromodomain-containing proteins BRD1,BRD2,and BRD13 are core subunits of SWI/SNF complexes and critical for SWI/SNF genomic targeting.These three BRDs interact directly with multiple SWI/SNF subunits,including the BRAHMA(BRM)catalytic subunit.Phenotypic and transcriptomic analyses of the brd1 brd2 brd13 triple mutant revealed that these BRDs act largely redundantly to control gene expression and developmental processes that are also regulated by BRM.Genome-wide occupancy profiling demonstrated that these three BRDs extensively colocalize with BRM on chromatin.Simultaneous loss of function of three BRD genes results in reduced BRM protein levels and decreased occupancy of BRM on chromatin across the genome.Furthermore,we demonstrated that the bromodomains of BRDs are essential for genomic targeting of the BRD subunits of SWI/SNF complexes to their target sites.Collectively,these results demonstrate that BRD1,BRD2,and BRD13 are core subunits of SWI/SNF complexes and reveal their biological roles in facilitating genomic targeting of BRM-containing SWI/SNF complexes in plants.展开更多
基金supported by the National Key Research and Development Program of China(2023YFC2306003)the National Natural Science Foundation of China(81972652,32270635)+4 种基金Natural Science Foundation of Beijing(7232082)the Capital Medical University Scientific Research Cultivation Fund for Natural Category(PYZ24164)the Training Fund for Open Projects at Clinical Institutes and Departments of Capital Medical University(CCMU2024ZKYXY015)the Science Foundation of Beijing Ditan Hospital,Capital Medical University(DTQH-202404)the Beijing Nova Program(Z201100006820051).
文摘Chronic hepatitis B is perpetuated by the presence of covalently closed circular DNA(cccDNA)from the hepatitis B virus(HBV)in the liver’s hepatocytes.Despite these efforts,the exact mechanisms by which the chromatin structure of cccDNA enables viral persistence remain unclear.This study investigates the vital role of mammalian SWI/SNF chromatin remodeling complexes in regulating the transcriptional activity of cccDNA.Our research,using pharmacological inhibitors and genetic techniques,identifies BRG1(SMARCA4),the central ATPase of the mSWI/SNF complexes,and BRD9,a non-canonical BAF(ncBAF)-specific subunit,as crucial host factors for HBV replication.The overexpression of SMARCA4 enhances viral propagation,whereas its targeted degradation using PROTAC AU15330 or siRNA significantly reduces cccDNA-driven transcription,viral transcripts,and protein levels.Chromatin accessibility assays demonstrate that the depletion of BRG1(SMARCA4)compacts the chromatin at critical cccDNA regulatory regions.Mechanistically,the HBV X protein(HBx)interacts with BAF155 and collaborates with transcription factor YY1 to promote the SWI/SNF complex binding to viral chromatin.Interestingly,inhibiting BRD9,an ncBAF-specific acetyl-lysine reader,similarly disrupts cccDNA transcription,indicating a coordinated function of canonical and non-canonical SWI/SNF complexes via acetylation-dependent chromatin remodeling.These insights highlight SWI/SNF complexes as key regulators of viral persistence and suggest targeting these complexes as a potential therapeutic strategy for eradicating cccDNA reservoirs,potentially leading to a functional cure for chronic HBV infection.
基金supported by the National Natural Science Foundation of China to C.L.(32000380 and 31870289)Guangdong Basic and Applied Basic Research Foundation to C.L.(2021A1515011286)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University to C.L(18lgzd12).
文摘Switch defective/sucrose non-fermentable(SWI/SNF)chromatin remodeling complexes are multi-subunit machines that play vital roles in the regulation of chromatin structure and gene expression.However,the mechanisms by which SWI/SNF complexes recognize their target loci in plants are not fully understood.Here,we show that the Arabidopsis thaliana bromodomain-containing proteins BRD1,BRD2,and BRD13 are core subunits of SWI/SNF complexes and critical for SWI/SNF genomic targeting.These three BRDs interact directly with multiple SWI/SNF subunits,including the BRAHMA(BRM)catalytic subunit.Phenotypic and transcriptomic analyses of the brd1 brd2 brd13 triple mutant revealed that these BRDs act largely redundantly to control gene expression and developmental processes that are also regulated by BRM.Genome-wide occupancy profiling demonstrated that these three BRDs extensively colocalize with BRM on chromatin.Simultaneous loss of function of three BRD genes results in reduced BRM protein levels and decreased occupancy of BRM on chromatin across the genome.Furthermore,we demonstrated that the bromodomains of BRDs are essential for genomic targeting of the BRD subunits of SWI/SNF complexes to their target sites.Collectively,these results demonstrate that BRD1,BRD2,and BRD13 are core subunits of SWI/SNF complexes and reveal their biological roles in facilitating genomic targeting of BRM-containing SWI/SNF complexes in plants.
