The term epigenetics refers to heritable changes not encoded by DNA. The organization of DNA into chromatin fibers affects gene expression in a heritable manner and is therefore one mechanism of epigenetic inheritance...The term epigenetics refers to heritable changes not encoded by DNA. The organization of DNA into chromatin fibers affects gene expression in a heritable manner and is therefore one mechanism of epigenetic inheritance. Large parts of eukaryotic genomes consist of constitutively highly condensed heterochromatin, important for maintaining genome integrity but also for silencing of genes within. Small RNA, together with factors typically associated with RNA interference （RNAi） targets homologous DNA sequences and recruits factors that modify the chromatin, com- monly resulting in formation of heterochromatin and silencing of target genes. The scope of this review is to provide an overview of the roles of small RNA and the RNAi components, Dicer, Argonaute and RNA dependent polymerases in epigenetic inheritance via heterochromatin formation, exemplified with pathways from unicellular eukaryotes, plants and animals.展开更多
MicroRNAs(miRNAs)are small noncoding RNAs,which play a central role in gene expression regulation and have been considered as excellent biomarker candidates for clinical diagnosis and prognosis.So far,many miRNAs dete...MicroRNAs(miRNAs)are small noncoding RNAs,which play a central role in gene expression regulation and have been considered as excellent biomarker candidates for clinical diagnosis and prognosis.So far,many miRNAs detection methods require polymerase chain reaction(PCR)amplification following reverse transcription of miRNAs.These processes are complicated and time-consuming.In this work,we have developed a simpler method for miRNA detection based on base stacking hybridization happening on the surface of NaYF_4:Yb,Er upconversion nanoparticles.In this method,the fluorescence of NaYF_4:Yb,Er upconversion nanoparticles were functionalized as a reference standard,which can improve the accuracy of miRNA detection.On the basis of these findings,we suggest this novel approach for miRNA detection could be applied as an accurate and specific technique for miRNAs detection.展开更多
The eukaryotic genome is packaged into a complex nucleoprotein structure named chromatin, balancing the compactness of genome and the accessibility of regulatory proteins and RNA polymerases to DNA. The mechanisms of ...The eukaryotic genome is packaged into a complex nucleoprotein structure named chromatin, balancing the compactness of genome and the accessibility of regulatory proteins and RNA polymerases to DNA. The mechanisms of the regulation of chromatin dynamics include the post-translational modification of histones, alteration of nucleosome positions by chromatin remodelers, replacement of canonical histones by histone variants with the aid of histone chaperones, and dynamic organization of the three-dimensional genome in the small nucleus. Histone variants are different from canonical histones by substitution of several amino acid residues or changes in amino acid sequence. Histone variants perform specialized functions such as altering nucleosome stability, dynamics, structure, as well as playing critical roles in a range of biological processes like transcriptional regulation, DNA repair and recombination, development and immune responses. Here we discuss how histone variants, their modification and specific loading to chromatin are involved in transcriptional regulation, DNA repair and plant development.展开更多
Within Baculoviridae, little is known about the molecular mechanisms of replication in betabaculoviruses, despite extensive studies in alphabaculoviruses. In this study, the promoters of nine late genes of the betabac...Within Baculoviridae, little is known about the molecular mechanisms of replication in betabaculoviruses, despite extensive studies in alphabaculoviruses. In this study, the promoters of nine late genes of the betabaculovirus Plutella xylostella granulovirus(Plxy GV) were cloned into a transient expression vector and the alphabaculovirus Autographa californica multiple nucleopolyhedrovirus(Ac MNPV) genome, and compared with homologous late gene promoters of Ac MNPV in Sf9 cells. In transient expression assays, all Plxy GV late promoters were activated in cells transfected with the individual reporter plasmids together with an Ac MNPV bacmid. In infected cells, reporter gene expression levels with the promoters of Plxy GV e18 and Ac MNPV vp39 and gp41 were significantly higher than those of the corresponding Ac MNPV or Plxy GV promoters,which had fewer late promoter motifs. Observed expression levels were lower for the Plxy GV p6.9,pk1, gran, p10 a, and p10 b promoters than for the corresponding Ac MNPV promoters, despite equal numbers of late promoter motifs, indicating that species-specific elements contained in some late promoters were favored by the native viral RNA polymerases for optimal transcription. The 8-nt sequence TAAATAAG encompassing the ATAAG motif was conserved in the Ac MNPV polh, p10,and pk1 promoters. The 5-nt sequence CAATT located 4 or 5 nt upstream of the T/ATAAG motif was conserved in the promoters of Plxy GV gran, p10 c, and pk1. The results of this study demonstrated that Plxy GV late gene promoters could be effectively activated by the RNA polymerase from Ac MNPV, implying that late gene expression systems are regulated by similar mechanisms in alphabaculoviruses and betabaculoviruses.展开更多
The nucleocapsid of vesicular stomatitis virus serves as the genomic template for transcription and replication. The viral genomic RNA is sequestered in the nucleocapsid in every step of the virus replication cycle. T...The nucleocapsid of vesicular stomatitis virus serves as the genomic template for transcription and replication. The viral genomic RNA is sequestered in the nucleocapsid in every step of the virus replication cycle. The structure of the nucleocapsid and the entire virion revealed how the viral genomic RNA is encapsidated and packaged in the virus. A unique mechanism for viral RNA synthesis is derived from the structure of the nuleocapsid and its interactions with the viral RNA-dependent RNA polymerase.展开更多
文摘The term epigenetics refers to heritable changes not encoded by DNA. The organization of DNA into chromatin fibers affects gene expression in a heritable manner and is therefore one mechanism of epigenetic inheritance. Large parts of eukaryotic genomes consist of constitutively highly condensed heterochromatin, important for maintaining genome integrity but also for silencing of genes within. Small RNA, together with factors typically associated with RNA interference （RNAi） targets homologous DNA sequences and recruits factors that modify the chromatin, com- monly resulting in formation of heterochromatin and silencing of target genes. The scope of this review is to provide an overview of the roles of small RNA and the RNAi components, Dicer, Argonaute and RNA dependent polymerases in epigenetic inheritance via heterochromatin formation, exemplified with pathways from unicellular eukaryotes, plants and animals.
基金the National Natural Science Foundation of China(61301039,21205036,31270908,61271056, 31540018)the Hunan Provincial Natural Science Foundation of China (13JJ4091)+2 种基金the Scientific Research Fund of Hunan Provincial Education Department(13A003)China Postdoctoral Science Foundation funded project(2014T70459)the Economical Forest Cultivation and Utilization of 2011 Collaborative Innovation Center in Hunan Province[(2013) 448]
文摘MicroRNAs(miRNAs)are small noncoding RNAs,which play a central role in gene expression regulation and have been considered as excellent biomarker candidates for clinical diagnosis and prognosis.So far,many miRNAs detection methods require polymerase chain reaction(PCR)amplification following reverse transcription of miRNAs.These processes are complicated and time-consuming.In this work,we have developed a simpler method for miRNA detection based on base stacking hybridization happening on the surface of NaYF_4:Yb,Er upconversion nanoparticles.In this method,the fluorescence of NaYF_4:Yb,Er upconversion nanoparticles were functionalized as a reference standard,which can improve the accuracy of miRNA detection.On the basis of these findings,we suggest this novel approach for miRNA detection could be applied as an accurate and specific technique for miRNAs detection.
基金supported by the National Natural Science Foundation of China(31171168 and 91319304)National Basic Research Program of China(2012CB910503)
文摘The eukaryotic genome is packaged into a complex nucleoprotein structure named chromatin, balancing the compactness of genome and the accessibility of regulatory proteins and RNA polymerases to DNA. The mechanisms of the regulation of chromatin dynamics include the post-translational modification of histones, alteration of nucleosome positions by chromatin remodelers, replacement of canonical histones by histone variants with the aid of histone chaperones, and dynamic organization of the three-dimensional genome in the small nucleus. Histone variants are different from canonical histones by substitution of several amino acid residues or changes in amino acid sequence. Histone variants perform specialized functions such as altering nucleosome stability, dynamics, structure, as well as playing critical roles in a range of biological processes like transcriptional regulation, DNA repair and recombination, development and immune responses. Here we discuss how histone variants, their modification and specific loading to chromatin are involved in transcriptional regulation, DNA repair and plant development.
基金supported by the fund of Hubei Key Laboratory of Genetic Regulation and Integrative Biology
文摘Within Baculoviridae, little is known about the molecular mechanisms of replication in betabaculoviruses, despite extensive studies in alphabaculoviruses. In this study, the promoters of nine late genes of the betabaculovirus Plutella xylostella granulovirus(Plxy GV) were cloned into a transient expression vector and the alphabaculovirus Autographa californica multiple nucleopolyhedrovirus(Ac MNPV) genome, and compared with homologous late gene promoters of Ac MNPV in Sf9 cells. In transient expression assays, all Plxy GV late promoters were activated in cells transfected with the individual reporter plasmids together with an Ac MNPV bacmid. In infected cells, reporter gene expression levels with the promoters of Plxy GV e18 and Ac MNPV vp39 and gp41 were significantly higher than those of the corresponding Ac MNPV or Plxy GV promoters,which had fewer late promoter motifs. Observed expression levels were lower for the Plxy GV p6.9,pk1, gran, p10 a, and p10 b promoters than for the corresponding Ac MNPV promoters, despite equal numbers of late promoter motifs, indicating that species-specific elements contained in some late promoters were favored by the native viral RNA polymerases for optimal transcription. The 8-nt sequence TAAATAAG encompassing the ATAAG motif was conserved in the Ac MNPV polh, p10,and pk1 promoters. The 5-nt sequence CAATT located 4 or 5 nt upstream of the T/ATAAG motif was conserved in the promoters of Plxy GV gran, p10 c, and pk1. The results of this study demonstrated that Plxy GV late gene promoters could be effectively activated by the RNA polymerase from Ac MNPV, implying that late gene expression systems are regulated by similar mechanisms in alphabaculoviruses and betabaculoviruses.
基金supported by the National Institutes of Health (Grant No. AI050066)
文摘The nucleocapsid of vesicular stomatitis virus serves as the genomic template for transcription and replication. The viral genomic RNA is sequestered in the nucleocapsid in every step of the virus replication cycle. The structure of the nucleocapsid and the entire virion revealed how the viral genomic RNA is encapsidated and packaged in the virus. A unique mechanism for viral RNA synthesis is derived from the structure of the nuleocapsid and its interactions with the viral RNA-dependent RNA polymerase.
