While human immunodeficiency virus 1(HIV-1) infectionis controlled through continuous, life-long use of a combination of drugs targeting different steps of the virus cycle, HIV-1 is never completely eradicated from th...While human immunodeficiency virus 1(HIV-1) infectionis controlled through continuous, life-long use of a combination of drugs targeting different steps of the virus cycle, HIV-1 is never completely eradicated from the body. Despite decades of research there is still no effective vaccine to prevent HIV-1 infection. Therefore, the possibility of an RNA interference(RNAi)-based cure has become an increasingly explored approach. Endogenous gene expression is controlled at both, transcriptional and post-transcriptional levels by noncoding RNAs, which act through diverse molecular mechanisms including RNAi. RNAi has the potential to control the turning on/off of specific genes through transcriptional gene silencing(TGS), as well as finetuning their expression through post-transcriptional gene silencing(PTGS). In this review we will describe in detail the canonical RNAi pathways for PTGS and TGS, the relationship of TGS with other silencing mechanisms and will discuss a variety of approaches developed to suppress HIV-1 via manipulation of RNAi. We will briefly compare RNAi strategies against other approaches developed to target the virus, highlighting their potential to overcome the major obstacle to finding a cure, which is the specific targeting of the HIV-1 reservoir within latently infected cells.展开更多
Post-transcriptional gene silencing mediated by microRNAs(miRNAs)modulates numerous developmental and stress response pathways.For the last two decades,HASTY(HST),the ortholog of human EXPORTIN 5,was considered to be ...Post-transcriptional gene silencing mediated by microRNAs(miRNAs)modulates numerous developmental and stress response pathways.For the last two decades,HASTY(HST),the ortholog of human EXPORTIN 5,was considered to be a candidate protein that exports plant miRNAs from the nucleus to the cytoplasm.Here,we report that HST functions in the miRNA pathway independent of its cargo-exporting activity in Arabidopsis.We found that Arabidopsis mutants with impaired HST shuttling exhibit normal subcellular distribution of miRNAs.Interestingly,protein-protein interaction and microscopy assays showed that HST directly interacts with the microprocessor core component DCL1 through its N-terminal domain.Moreover,mass spectrometry analysis revealed that HST also interacts independently of its N-terminal domain with the mediator complex subunit MED37.Further experiments revealed that HST could act as a scaffold to facilitate the recruitment of DCL1 to genomic MIRNA loci by stabilizing the DCL1-MED37 complex,which in turn promotes the transcription and proper processing of primary miRNA transcripts(primiRNAs).Taken together,these results suggest that HST is likely associated with the formation of the miRNA biogenesis complex at MIRNA genes,promoting the transcription and processing of primiRNAs rather than the direct export of processed miRNAs from the nucleus.展开更多
In plants, post-transcriptional gene silencing(PTGS) protects the genome from foreign genes and restricts the expression of certain endogenous genes for proper development. Here, we review the recent progress about ho...In plants, post-transcriptional gene silencing(PTGS) protects the genome from foreign genes and restricts the expression of certain endogenous genes for proper development. Here, we review the recent progress about how the unwanted PTGS is avoided in plants. As a decision-making step of PTGS, aberrant transcripts from most endogenous coding genes are strictly sorted to the bidirectional RNA decay pathways in cytoplasm but not to the short interference RNA(si RNA)-mediated PTGS, with the exception of a few development-relevant endogenous si RNA-producing genes. We also discuss a finely balanced PTGS threshold model that plants fully take advantage of the power of PTGS without self-harm.展开更多
Plant Dicer-like(DCL)and Argonaute(AGO)are the key enzymes involved in anti-virus post-transcriptional gene silencing(AV-PTGS).Here we show that AV-PTGS exhibited nucleotide preference by calculating a relative AV-PTG...Plant Dicer-like(DCL)and Argonaute(AGO)are the key enzymes involved in anti-virus post-transcriptional gene silencing(AV-PTGS).Here we show that AV-PTGS exhibited nucleotide preference by calculating a relative AV-PTGS efficiency on processing viral RNA substrates.In comparison with genome sequences of dicot-infecting Turnip mosaic virus(TuMV)and monocot-infecting Cocksfoot streak virus(CSV),viral-derived small interfering RNAs(vsiRNAs)displayed positive correlations between AV-PTGS efficiency and G+C content(GC%).Further investigations on nucleotide contents revealed that the vsiRNA populations had G-biases.This finding was further supported by our analyses of previously reported vsiRNA populations in diverse plant-virus associations,and AGO associated Arabidopsis endogenous siRNA populations,indicating that plant AGOs operated with G-preference.We further propose a hypothesis that AV-PTGS imposes selection pressure(s)on the evolution of plant viruses.This hypothesis was supported when potyvirus genomes were analysed for evidence of GC elimination,suggesting that plant virus evolution to have low GC%genomes would have a unique function,which is to reduce the host AV-PTGS attack during infections.展开更多
Tomato yellow leaf curl virus(TYLCV)is known to encode 6 canonical viral proteins.Our recent study revealed that TYLCV also encodes some additional small proteins with potential virulence functions.The fifth ORF of TY...Tomato yellow leaf curl virus(TYLCV)is known to encode 6 canonical viral proteins.Our recent study revealed that TYLCV also encodes some additional small proteins with potential virulence functions.The fifth ORF of TYLCV in the complementary sense,which we name C5,is evolutionarily conserved,but little is known about its expression and function during viral infection.Here,we confirmed the expression of the TYLCV C5 by analyzing the promoter activity of its upstream sequences and by detecting the C5 protein in infected cells by using a specific custom-made antibody.Ectopic expression of C5 using a potato virus X(PVX)vector resulted in severe mosaic symptoms and higher virus accumulation levels followed by a burst of reactive oxygen species(ROS)in Nicotiana benthamiana plants.C5 was able to effectively suppress local and systemic post-transcriptional gene silencing(PTGS)induced by single-stranded GFP but not double-stranded GFP,and reversed the transcriptional gene silencing(TGS)of GFP.Furthermore,the mutation of C5 in TYLCV inhibited viral replication and the development of disease symptoms in infected plants.Transgenic overexpression of C5 could complement the virulence of a TYLCV infectious clone encoding a dysfunctional C5.Collectively,this study reveals that TYLCV C5 is a pathogenicity determinant and RNA silencing suppressor,hence expanding our knowledge of the functional repertoire of the TYLCV proteome.展开更多
Multicellular organisms, like higher plants, need to coordinate their growth and development and to cope with environmental cues. To achieve this, various signal molecules are transported between neighboring cells and...Multicellular organisms, like higher plants, need to coordinate their growth and development and to cope with environmental cues. To achieve this, various signal molecules are transported between neighboring cells and distant organs to control the fate of the recipient cells and organs. RNA silencing produces cell non-autonomous signal molecules that can move over short or long distances leading to the sequence specific silencing of a target gene in a well defined area of cells or throughout the entire plant,respectively. The nature of these signal molecules, the route of silencing spread, and the genes involved in their production, movement and reception are discussed in this review. Additionally, a short section on features of silencing spread in animal models is presented at the end of this review.展开更多
文摘While human immunodeficiency virus 1(HIV-1) infectionis controlled through continuous, life-long use of a combination of drugs targeting different steps of the virus cycle, HIV-1 is never completely eradicated from the body. Despite decades of research there is still no effective vaccine to prevent HIV-1 infection. Therefore, the possibility of an RNA interference(RNAi)-based cure has become an increasingly explored approach. Endogenous gene expression is controlled at both, transcriptional and post-transcriptional levels by noncoding RNAs, which act through diverse molecular mechanisms including RNAi. RNAi has the potential to control the turning on/off of specific genes through transcriptional gene silencing(TGS), as well as finetuning their expression through post-transcriptional gene silencing(PTGS). In this review we will describe in detail the canonical RNAi pathways for PTGS and TGS, the relationship of TGS with other silencing mechanisms and will discuss a variety of approaches developed to suppress HIV-1 via manipulation of RNAi. We will briefly compare RNAi strategies against other approaches developed to target the virus, highlighting their potential to overcome the major obstacle to finding a cure, which is the specific targeting of the HIV-1 reservoir within latently infected cells.
基金This work was supported by grants from the ANPCyT(Agencia Nacional de Promocio´n Cientı´fica y Tecnolo´gica,Argentina)the HFSP(Human Frontier Science Program)+1 种基金the ICGEB(International Center for Genetic Engineering and Biotechnology)to P.A.M.and from the Max Planck Society to P.A.M.and D.W.P.A.M.and A.L.A.are members of CONICETD.A.C.,A.J.G.,and D.G.are fellows of the same institution.
文摘Post-transcriptional gene silencing mediated by microRNAs(miRNAs)modulates numerous developmental and stress response pathways.For the last two decades,HASTY(HST),the ortholog of human EXPORTIN 5,was considered to be a candidate protein that exports plant miRNAs from the nucleus to the cytoplasm.Here,we report that HST functions in the miRNA pathway independent of its cargo-exporting activity in Arabidopsis.We found that Arabidopsis mutants with impaired HST shuttling exhibit normal subcellular distribution of miRNAs.Interestingly,protein-protein interaction and microscopy assays showed that HST directly interacts with the microprocessor core component DCL1 through its N-terminal domain.Moreover,mass spectrometry analysis revealed that HST also interacts independently of its N-terminal domain with the mediator complex subunit MED37.Further experiments revealed that HST could act as a scaffold to facilitate the recruitment of DCL1 to genomic MIRNA loci by stabilizing the DCL1-MED37 complex,which in turn promotes the transcription and proper processing of primary miRNA transcripts(primiRNAs).Taken together,these results suggest that HST is likely associated with the formation of the miRNA biogenesis complex at MIRNA genes,promoting the transcription and processing of primiRNAs rather than the direct export of processed miRNAs from the nucleus.
基金supported by the National Basic Research Program of China(2012CB910902)the National Natural Science Foundation of China(9121730591017010)to H.G
文摘In plants, post-transcriptional gene silencing(PTGS) protects the genome from foreign genes and restricts the expression of certain endogenous genes for proper development. Here, we review the recent progress about how the unwanted PTGS is avoided in plants. As a decision-making step of PTGS, aberrant transcripts from most endogenous coding genes are strictly sorted to the bidirectional RNA decay pathways in cytoplasm but not to the short interference RNA(si RNA)-mediated PTGS, with the exception of a few development-relevant endogenous si RNA-producing genes. We also discuss a finely balanced PTGS threshold model that plants fully take advantage of the power of PTGS without self-harm.
基金supported by the Vietnamese Studentship to TH(Ministry of Education and Training,Decision No 322/QD-TTg)NERC(UK)grants to TD(NER/A/S/2003/00547)+1 种基金HW(NER/A/S/2003/00548,NE/E008933/1)CEH Biodiversity research fund to HW(C02875).
文摘Plant Dicer-like(DCL)and Argonaute(AGO)are the key enzymes involved in anti-virus post-transcriptional gene silencing(AV-PTGS).Here we show that AV-PTGS exhibited nucleotide preference by calculating a relative AV-PTGS efficiency on processing viral RNA substrates.In comparison with genome sequences of dicot-infecting Turnip mosaic virus(TuMV)and monocot-infecting Cocksfoot streak virus(CSV),viral-derived small interfering RNAs(vsiRNAs)displayed positive correlations between AV-PTGS efficiency and G+C content(GC%).Further investigations on nucleotide contents revealed that the vsiRNA populations had G-biases.This finding was further supported by our analyses of previously reported vsiRNA populations in diverse plant-virus associations,and AGO associated Arabidopsis endogenous siRNA populations,indicating that plant AGOs operated with G-preference.We further propose a hypothesis that AV-PTGS imposes selection pressure(s)on the evolution of plant viruses.This hypothesis was supported when potyvirus genomes were analysed for evidence of GC elimination,suggesting that plant virus evolution to have low GC%genomes would have a unique function,which is to reduce the host AV-PTGS attack during infections.
基金funded by the National Key Research and Development Program of China(2021YFD1400400)the National Natural Science Foundation of China(32172385 and 3193089).
文摘Tomato yellow leaf curl virus(TYLCV)is known to encode 6 canonical viral proteins.Our recent study revealed that TYLCV also encodes some additional small proteins with potential virulence functions.The fifth ORF of TYLCV in the complementary sense,which we name C5,is evolutionarily conserved,but little is known about its expression and function during viral infection.Here,we confirmed the expression of the TYLCV C5 by analyzing the promoter activity of its upstream sequences and by detecting the C5 protein in infected cells by using a specific custom-made antibody.Ectopic expression of C5 using a potato virus X(PVX)vector resulted in severe mosaic symptoms and higher virus accumulation levels followed by a burst of reactive oxygen species(ROS)in Nicotiana benthamiana plants.C5 was able to effectively suppress local and systemic post-transcriptional gene silencing(PTGS)induced by single-stranded GFP but not double-stranded GFP,and reversed the transcriptional gene silencing(TGS)of GFP.Furthermore,the mutation of C5 in TYLCV inhibited viral replication and the development of disease symptoms in infected plants.Transgenic overexpression of C5 could complement the virulence of a TYLCV infectious clone encoding a dysfunctional C5.Collectively,this study reveals that TYLCV C5 is a pathogenicity determinant and RNA silencing suppressor,hence expanding our knowledge of the functional repertoire of the TYLCV proteome.
基金co-financed by the European Union(European Social Fund–ESF)Greek national funds through the Operational Program"Education and Lifelong Learning"of the National Strategic Reference Framework(NSRF)–Research Funding Program:Heracleitus Ⅱ+1 种基金the European Social Fund(G.M.)Postdoctoral Grant LS1-1190(F.V)
文摘Multicellular organisms, like higher plants, need to coordinate their growth and development and to cope with environmental cues. To achieve this, various signal molecules are transported between neighboring cells and distant organs to control the fate of the recipient cells and organs. RNA silencing produces cell non-autonomous signal molecules that can move over short or long distances leading to the sequence specific silencing of a target gene in a well defined area of cells or throughout the entire plant,respectively. The nature of these signal molecules, the route of silencing spread, and the genes involved in their production, movement and reception are discussed in this review. Additionally, a short section on features of silencing spread in animal models is presented at the end of this review.
