Circular intronic RNAs(ci RNAs) escaping from DBR1 debranching of intron lariats are co-transcriptionally produced from prem RNA splicing, but their turnover and mechanism of action have remained elusive. We report th...Circular intronic RNAs(ci RNAs) escaping from DBR1 debranching of intron lariats are co-transcriptionally produced from prem RNA splicing, but their turnover and mechanism of action have remained elusive. We report that RNase H1 degrades a subgroup of ci RNAs in human cells. Many ci RNAs contain high GC% and tend to form DNA:RNA hybrids(R-loops) for RNase H1 cleavage, a process that appears to promote Pol II transcriptional elongation at ci RNA-producing loci. One ci RNA, ciankrd52, shows a stronger ability of R-loop formation than that of its cognate pre-m RNA by maintaining a locally open RNA structure in vitro. This allows the release of pre-m RNA from R-loops by ci-ankrd52 replacement and subsequent ci RNA removal via RNase H1 for efficient transcriptional elongation. We propose that such an R-loop dependent ci RNA degradation likely represents a mechanism that on one hand limits ci RNA accumulation by recruiting RNase H1 and on the other hand resolves Rloops for transcriptional elongation at some GC-rich ci RNA-producing loci.展开更多
Centromeres play a vital role in cellular division by facilitating kinetochore assembly and spindle attachments.Despite their conserved functionality,centromeric DNA sequences exhibit rapid evolution,presenting divers...Centromeres play a vital role in cellular division by facilitating kinetochore assembly and spindle attachments.Despite their conserved functionality,centromeric DNA sequences exhibit rapid evolution,presenting diverse sizes and compositions across species.The functional significance of rye centromeric DNA sequences,particularly in centromere identity,remains unclear.In this study,we comprehensively characterized the sequence composition and organization of rye centromeres.Our findings revealed that these centromeres are primarily composed of long terminal repeat retrotransposons(LTR-RTs)and interspersed minisatellites.We systematically classified LTR-RTs into five categories,highlighting the prevalence of younger CRS1,CRS2,and CRS3 of CRSs(centromeric retrotransposons of Secale cereale)were primarily located in the core centromeres and exhibited a higher association with CENH3 nucleosomes.The minisatellites,mainly derived from retrotransposons,along with CRSs,played a pivotal role in establishing functional centromeres in rye.Additionally,we observed the formation of R-loops at specific regions of CRS1,CRS2,and CRS3,with both rye pericentromeres and centromeres exhibiting enrichment in R-loops.Notably,these R-loops selectively formed at binding regions of the CENH3 nucleosome in rye centromeres,suggesting a potential role in mediating the precise loading of CENH3 to centromeres and contributing to centromere specification.Our work provides insights into the DNA sequence composition,distribution,and potential function of R-loops in rye centromeres.This knowledge contributes valuable information to understanding the genetics and epigenetics of rye centromeres,offering implications for the development of synthetic centromeres in future plant modifications and beyond.展开更多
RNA-mediated mechanisms of disease pathogenesis in neurological disorders have been recognized in the context of certain repeat expansion disorders. This RNA-initiated neurodegeneration may play a more pervasive role ...RNA-mediated mechanisms of disease pathogenesis in neurological disorders have been recognized in the context of certain repeat expansion disorders. This RNA-initiated neurodegeneration may play a more pervasive role in disease pathology beyond the classic dynamic mutation disorders. Here, we review the mechanisms of RNA toxicity and aberrant RNA processing that have been implicated in ageing-related neurological disorders. We focus on diseases with aberrant sequestration of RNA-binding proteins, bi-directional tran- scription, aberrant translation of repeat expansion RNA transcripts （repeat-associated non-ATG （RAN） translation）, and the formation of pathological RNA：DNA secondary structure （R-loop）. It is likely that repeat expansion disorders arise from common mechanisms caused by the repeat expansion mutations. However, the context of the repeat expansion determines the specific molecular consequences, leading to clinically distinct disorders.展开更多
An R-loop is a three-stranded chromatin structure that consists of a displaced single strand of DNA and an RNA:DNA hybrid duplex,which was thought to be a rare by-product of transcription.However,recent genome-wide da...An R-loop is a three-stranded chromatin structure that consists of a displaced single strand of DNA and an RNA:DNA hybrid duplex,which was thought to be a rare by-product of transcription.However,recent genome-wide data have shown that R-loops are widespread and pervasive in a variety of genomes,and a growing body of experimental evidence indicates that R-loops have both beneficial and harmful effects on an organism.To maximize benefit and avoid harm,organisms have evolved several means by which they tightly regulate R-loop levels.Here,we summarize our current understanding of the biogenesis and effects of R-loops,the mechanisms that regulate them,and methods of R-loop profiling,reviewing recent research advances on R-loops in plants.Furthermore,we provide perspectives on future research directions for R-loop biology in plants,which might lead to a more comprehensive understanding of R-loop functions in plant genome regulation and contribute to future agricultural improvements.展开更多
Circular RNAs(circRNAs)are a recently dis-covered type of non‐coding RNA derived from pre‐mRNAs.R‐loops consist of a DNA:RNA hybrid andthe associated single‐stranded DNA.InArabi-dopsis thaliana,circRNA:DNA R‐loop...Circular RNAs(circRNAs)are a recently dis-covered type of non‐coding RNA derived from pre‐mRNAs.R‐loops consist of a DNA:RNA hybrid andthe associated single‐stranded DNA.InArabi-dopsis thaliana,circRNA:DNA R‐loops regulatealternative splicing(AS)ofSEPALLATA3(SEP3).However,the occurrence and functions ofcircRNAs and R‐loops inPopulus trichocarpaarelargely unexplored.Here,we performed circRNA‐enriched sequencing in the stem‐differentiatingxylem(SDX)ofP.trichocarpaand identified 2,742distinct circRNAs,including circ‐CESA4,circ‐IRX7,and circ‐GUX1,which are generated from genesinvolved in cellulose,and hemicellulose biosyn-thesis,respectively.To investigate the roles ofcircRNAs in modulating alternative splicing(AS),we detected 7,836 AS events using PacBio Iso‐Seq and identified 634 circRNAs that overlappedwith 699 AS events.Furthermore,using DNA:RNAhybrid immunoprecipitation followed by se-quencing(DRIP‐seq),we identified 8,932 R‐looppeaks that overlapped with 181 circRNAs and 672AS events.Notably,several SDX‐related circRNAsoverlapped with R‐loop peaks,pointing to theirpossible roles in modulating AS in SDX.Indeed,overexpressing circ‐IRX7increased the levels ofR‐loop structures and decreased the frequency ofintron retention in linearIRX7transcripts.Thisstudy provides a valuable R‐loop atlas resourceand uncovers the interplay between circRNAs andAS in SDX ofP.trichocarpa.展开更多
Enhancers modulate gene expression by interacting with promoters.Models of enhancer-promoter interactions(EPIs)in the literature involve the activity of many components,including transcription factors and nucleic acid...Enhancers modulate gene expression by interacting with promoters.Models of enhancer-promoter interactions(EPIs)in the literature involve the activity of many components,including transcription factors and nucleic acid.However,the role that sequence similarity plays in EPIs remains largely unexplored.Herein,we report that Alu-derived sequences dominate sequence similarity between enhancers and promoters.After rejecting alternative DNA:DNA and DNA:RNA triplex models,we propose that enhancer-associated RNAs(eRNAs)may directly contact their targeted promoters by forming trans-acting R-loops at those Alu sequences.We show how the characteristic distribution of functional genomic data,such as RNA-DNA proximate ligation reads,binding of transcription factors,and RNA-binding proteins,all align with the Alu sequences of EPIs.We also show that these aligned Alu sequences may be subject to the constraint of coevolution,further implying the functional significance of these R-loop hybrids.Finally,our results imply that eRNA and Alu elements associate in a manner previously unrecognized in EPIs and the evolution of gene regulation networks in mammals.展开更多
基金This work was supported by the National Natural Science Foundation of China(NSFC)(91940303,31725009)the HHMI International Program(55008728)to L.-L.C.+2 种基金NSFC(31730111,31925011)to L.Y.Young Elite Scientists Sponsorship Program(2020QNRC001)to X.L.L.-L.C.the support from the XPLORER PRIZE.
文摘Circular intronic RNAs(ci RNAs) escaping from DBR1 debranching of intron lariats are co-transcriptionally produced from prem RNA splicing, but their turnover and mechanism of action have remained elusive. We report that RNase H1 degrades a subgroup of ci RNAs in human cells. Many ci RNAs contain high GC% and tend to form DNA:RNA hybrids(R-loops) for RNase H1 cleavage, a process that appears to promote Pol II transcriptional elongation at ci RNA-producing loci. One ci RNA, ciankrd52, shows a stronger ability of R-loop formation than that of its cognate pre-m RNA by maintaining a locally open RNA structure in vitro. This allows the release of pre-m RNA from R-loops by ci-ankrd52 replacement and subsequent ci RNA removal via RNase H1 for efficient transcriptional elongation. We propose that such an R-loop dependent ci RNA degradation likely represents a mechanism that on one hand limits ci RNA accumulation by recruiting RNase H1 and on the other hand resolves Rloops for transcriptional elongation at some GC-rich ci RNA-producing loci.
基金supported by the National Natural Science Foundation of China(31991212,31920103006)。
文摘Centromeres play a vital role in cellular division by facilitating kinetochore assembly and spindle attachments.Despite their conserved functionality,centromeric DNA sequences exhibit rapid evolution,presenting diverse sizes and compositions across species.The functional significance of rye centromeric DNA sequences,particularly in centromere identity,remains unclear.In this study,we comprehensively characterized the sequence composition and organization of rye centromeres.Our findings revealed that these centromeres are primarily composed of long terminal repeat retrotransposons(LTR-RTs)and interspersed minisatellites.We systematically classified LTR-RTs into five categories,highlighting the prevalence of younger CRS1,CRS2,and CRS3 of CRSs(centromeric retrotransposons of Secale cereale)were primarily located in the core centromeres and exhibited a higher association with CENH3 nucleosomes.The minisatellites,mainly derived from retrotransposons,along with CRSs,played a pivotal role in establishing functional centromeres in rye.Additionally,we observed the formation of R-loops at specific regions of CRS1,CRS2,and CRS3,with both rye pericentromeres and centromeres exhibiting enrichment in R-loops.Notably,these R-loops selectively formed at binding regions of the CENH3 nucleosome in rye centromeres,suggesting a potential role in mediating the precise loading of CENH3 to centromeres and contributing to centromere specification.Our work provides insights into the DNA sequence composition,distribution,and potential function of R-loops in rye centromeres.This knowledge contributes valuable information to understanding the genetics and epigenetics of rye centromeres,offering implications for the development of synthetic centromeres in future plant modifications and beyond.
基金supported in part by the grants from the National Natural Science Foundation of China(Nos.81071028 and 81172513 to R.D.)the National Basic Research Program of China(973 Program)(Nos.2012CB944600 and 2011CB510000 to R.D.)+2 种基金Program for New Century Excellent Talents(No.7603230006 to R.D.)the National Institutes of Health(NS079625 to P.J.)March of Dimes(FY13-354 to P.J.)
文摘RNA-mediated mechanisms of disease pathogenesis in neurological disorders have been recognized in the context of certain repeat expansion disorders. This RNA-initiated neurodegeneration may play a more pervasive role in disease pathology beyond the classic dynamic mutation disorders. Here, we review the mechanisms of RNA toxicity and aberrant RNA processing that have been implicated in ageing-related neurological disorders. We focus on diseases with aberrant sequestration of RNA-binding proteins, bi-directional tran- scription, aberrant translation of repeat expansion RNA transcripts （repeat-associated non-ATG （RAN） translation）, and the formation of pathological RNA：DNA secondary structure （R-loop）. It is likely that repeat expansion disorders arise from common mechanisms caused by the repeat expansion mutations. However, the context of the repeat expansion determines the specific molecular consequences, leading to clinically distinct disorders.
基金the National Natural Science Foundation of China(Grant Nos.91740105 and 31822028 to Q.Sun32100428 to J.Zhou+2 种基金and 32070651 to W.Zhang)supported by the Tsinghua-Peking Center for Life Sciencessupported by postdoc fellowships from the Tsinghua-Peking Center for Life Sciences。
文摘An R-loop is a three-stranded chromatin structure that consists of a displaced single strand of DNA and an RNA:DNA hybrid duplex,which was thought to be a rare by-product of transcription.However,recent genome-wide data have shown that R-loops are widespread and pervasive in a variety of genomes,and a growing body of experimental evidence indicates that R-loops have both beneficial and harmful effects on an organism.To maximize benefit and avoid harm,organisms have evolved several means by which they tightly regulate R-loop levels.Here,we summarize our current understanding of the biogenesis and effects of R-loops,the mechanisms that regulate them,and methods of R-loop profiling,reviewing recent research advances on R-loops in plants.Furthermore,we provide perspectives on future research directions for R-loop biology in plants,which might lead to a more comprehensive understanding of R-loop functions in plant genome regulation and contribute to future agricultural improvements.
基金supported by the National Key R&D Programof China(2016YFD0600106).
文摘Circular RNAs(circRNAs)are a recently dis-covered type of non‐coding RNA derived from pre‐mRNAs.R‐loops consist of a DNA:RNA hybrid andthe associated single‐stranded DNA.InArabi-dopsis thaliana,circRNA:DNA R‐loops regulatealternative splicing(AS)ofSEPALLATA3(SEP3).However,the occurrence and functions ofcircRNAs and R‐loops inPopulus trichocarpaarelargely unexplored.Here,we performed circRNA‐enriched sequencing in the stem‐differentiatingxylem(SDX)ofP.trichocarpaand identified 2,742distinct circRNAs,including circ‐CESA4,circ‐IRX7,and circ‐GUX1,which are generated from genesinvolved in cellulose,and hemicellulose biosyn-thesis,respectively.To investigate the roles ofcircRNAs in modulating alternative splicing(AS),we detected 7,836 AS events using PacBio Iso‐Seq and identified 634 circRNAs that overlappedwith 699 AS events.Furthermore,using DNA:RNAhybrid immunoprecipitation followed by se-quencing(DRIP‐seq),we identified 8,932 R‐looppeaks that overlapped with 181 circRNAs and 672AS events.Notably,several SDX‐related circRNAsoverlapped with R‐loop peaks,pointing to theirpossible roles in modulating AS in SDX.Indeed,overexpressing circ‐IRX7increased the levels ofR‐loop structures and decreased the frequency ofintron retention in linearIRX7transcripts.Thisstudy provides a valuable R‐loop atlas resourceand uncovers the interplay between circRNAs andAS in SDX ofP.trichocarpa.
基金the National Natural Science Foundation of China of China(91940304,31871331,31671342)Beijing Natural Science Foundation(Z200021)+2 种基金Special Investigation on Science and Technology Basic Resources of MOST,China(2019FY100102)the National Key R&D Program of China(2018YFC2000400)the Beijing Advanced Discipline Fund(115200S001)。
文摘Enhancers modulate gene expression by interacting with promoters.Models of enhancer-promoter interactions(EPIs)in the literature involve the activity of many components,including transcription factors and nucleic acid.However,the role that sequence similarity plays in EPIs remains largely unexplored.Herein,we report that Alu-derived sequences dominate sequence similarity between enhancers and promoters.After rejecting alternative DNA:DNA and DNA:RNA triplex models,we propose that enhancer-associated RNAs(eRNAs)may directly contact their targeted promoters by forming trans-acting R-loops at those Alu sequences.We show how the characteristic distribution of functional genomic data,such as RNA-DNA proximate ligation reads,binding of transcription factors,and RNA-binding proteins,all align with the Alu sequences of EPIs.We also show that these aligned Alu sequences may be subject to the constraint of coevolution,further implying the functional significance of these R-loop hybrids.Finally,our results imply that eRNA and Alu elements associate in a manner previously unrecognized in EPIs and the evolution of gene regulation networks in mammals.
