Epigenomic profiles of Brachypodium distachyon mutants deficient in RNA polymerase IV (Pol IV)
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PROVIDER: PRJNA1019624 | ENA |
REPOSITORIES: ENA
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Project description:Monocot grass species (Poaceae) express a diverse set of multisubunit RNA polymerase enzymes, including Pol II, Pol IV and Pol V. To better understand this functional diversity, we have charted Pol IV function in the model Brachypodium distachyon. Intriguingly, pol IV null mutations in Poaceae crops disrupt growth, reproductive development and seed set. In order to investigate how Pol IV controls vegetative growth and TE activity in these grasses, we have isolated B. distachyon mutant alleles for Pol IV’s largest subunit, NRPD1. We obtained the germplasm in which to screen for these pol IV mutations from the B. distachyon community's sodium azide (NaN) and T-DNA insertion collections.
2024-03-04 | GSE243693 | GEO
Project description:Eukaryotes must balance the need for gene transcription by RNA polymerase II (Pol II) against the danger of mutations caused by transposable element (TE) proliferation. In plants, these gene expression and TE silencing activities are divided between different RNA polymerases. Specifically, RNA polymerase IV (Pol IV), which evolved from Pol II, transcribes TEs to generate small interfering RNAs (siRNAs) that guide DNA methylation and block TE transcription by Pol II. While the Pol IV complex is recruited to TEs via SNF2-like CLASSY (CLSY) proteins, how Pol IV partners with the CLSYs remains unknown. Here we identified a conserved CYC-YPMF motif that is specific to Pol IV and is positioned on the complex exterior. Furthermore, we found that this motif is essential for the co-purification of all four CLSYs with Pol IV, but that only one CLSY is present in any given Pol IV complex. These findings support a “one CLSY per Pol IV” model where the CYC-YPMF motif acts as a CLSY-docking site. Indeed, mutations in and around this motif phenocopy pol iv null mutants. Together, these findings provide structural and functional insights into a critical protein feature that distinguishes Pol IV from other RNA polymerases, allowing it to promote genome stability by targeting TEs for silencing.
2024-10-01 | GSE278181 | GEO
Project description:Eukaryotes must balance the need for gene transcription by RNA polymerase II (Pol II) against the danger of mutations caused by transposable element (TE) proliferation. In plants, these gene expression and TE silencing activities are divided between different RNA polymerases. Specifically, RNA polymerase IV (Pol IV), which evolved from Pol II, transcribes TEs to generate small interfering RNAs (siRNAs) that guide DNA methylation and block TE transcription by Pol II. While the Pol IV complex is recruited to TEs via SNF2-like CLASSY (CLSY) proteins, how Pol IV partners with the CLSYs remains unknown. Here we identified a conserved CYC-YPMF motif that is specific to Pol IV and is positioned on the complex exterior. Furthermore, we found that this motif is essential for the co-purification of all four CLSYs with Pol IV, but that only one CLSY is present in any given Pol IV complex. These findings support a “one CLSY per Pol IV” model where the CYC-YPMF motif acts as a CLSY-docking site. Indeed, mutations in and around this motif phenocopy pol iv null and clsy quadruple mutants. Together, these findings provide structural and functional insights into a critical protein feature that distinguishes Pol IV from other RNA polymerases, allowing it to promote genome stability by targeting TEs for silencing.
2024-08-22 | GSE242191 | GEO
Project description:Maize RNA Polymerase D1 (RPD1), the largest subunit of RNA polymerase IV (Pol IV), is required for normal plant development, repression of transposable elements (TEs), and for the regulation of specific alleles associated with TEs. Here, we define the nascent transcriptomes of rpd1 mutant and wild-type (WT) seedlings using global run-on sequencing (GRO-seq) to identify the broader targets of RPD1-based transcriptional regulation. Surprisingly, although TE-like sequences comprise >85% of the maize genome, most TEs are not transcribed at the seedling stage, even in rpd1 mutants. Profile comparisons identify the global set of genes and TEs whose transcription is altered in the absence of RPD1, in some cases in antisense orientation. These results indicate that maize Pol IV specifies Pol II-based transcriptional regulation for certain regions of the maize genome. Nuclei isolated from 10 wild-type and 10 rpd1 mutant seedlings were pooled and used to make two global run-on sequencing libraries.
2015-02-04 | E-GEOD-54166 | biostudies-arrayexpress
Project description:Maize RNA Polymerase D1 (RPD1), the largest subunit of RNA polymerase IV (Pol IV), is required for normal plant development, repression of transposable elements (TEs), and for the regulation of specific alleles associated with TEs. Here, we define the nascent transcriptomes of rpd1 mutant and wild-type (WT) seedlings using global run-on sequencing (GRO-seq) to identify the broader targets of RPD1-based transcriptional regulation. Surprisingly, although TE-like sequences comprise >85% of the maize genome, most TEs are not transcribed at the seedling stage, even in rpd1 mutants. Profile comparisons identify the global set of genes and TEs whose transcription is altered in the absence of RPD1, in some cases in antisense orientation. These results indicate that maize Pol IV specifies Pol II-based transcriptional regulation for certain regions of the maize genome.
2015-02-04 | GSE54166 | GEO
Project description:In Arabidopsis thaliana, DNA-dependent RNA polymerase IV (Pol IV) is required for the formation of transposable element (TE)-derived small RNA (sRNA) transcripts. These transcripts are processed by DICER-LIKE3 into 24-nt small interfering RNAs (siRNAs) that guide RNA-directed DNA methylation. In the pollen grain, Pol IV is also required for the accumulation of 21/22-nt epigenetically activated siRNAs (easiRNAs), which likely silence TEs via post-transcriptional mechanisms. Despite this proposed role of Pol IV, its loss of function in Arabidopsis does not cause a discernable pollen defect. Here, we show that the knockout of NRPD1, encoding the largest subunit of Pol IV in the Brassicaceae species Capsella rubella, caused post-meiotic arrest of pollen development at the microspore stage. As in Arabidopsis, all TE-derived siRNAs were 2 depleted in Capsella nrpd1 microspores. In the wild-type background, the same TEs produced 21/22-nt and 24-nt siRNAs; these processes required Pol IV activity. Arrest of Capsella nrpd1 microspores was accompanied by the deregulation of genes targeted by Pol IV-dependent siRNAs. TEs were much closer to genes in Capsella rubella compared to Arabidopsis thaliana, perhaps explaining the essential role of Pol IV in pollen development in Capsella. Our discovery that Pol IV is functionally required in Capsella microspores emphasizes the relevance of investigating different plant models.
2020-01-23 | GSE136847 | GEO
Project description:Gene expression in endosperm – a seed tissue that mediates transfer of maternal resources to offspring – is under complex epigenetic control. We show here that plant-specific RNA Polymerase IV mediates parental control of endosperm gene expression. Pol IV is required for the production of small interfering RNAs that typically direct DNA methylation. We compared small RNAs, DNA methylation, and mRNAs in A. thaliana endosperm from reciprocal heterozygotes produced by crossing wild-type plants to Pol IV mutants. We find that maternally and paternally acting Pol IV have divergent effects on endosperm. Losses of maternal and paternal Pol IV impact sRNAs and DNA methylation at distinct genomic sites. Strikingly, maternally and paternally-acting Pol IV have antagonistic impacts on gene expression at some loci, divergently promoting or repressing endosperm gene expression. Antagonistic parent-of origin effects have only rarely been described and are consistent with a gene regulatory system evolving under parental conflict
2022-03-04 | GSE197715 | GEO
Project description:Gene expression in endosperm – a seed tissue that mediates transfer of maternal resources to offspring – is under complex epigenetic control. We show here that plant-specific RNA Polymerase IV mediates parental control of endosperm gene expression. Pol IV is required for the production of small interfering RNAs that typically direct DNA methylation. We compared small RNAs, DNA methylation, and mRNAs in A. thaliana endosperm from reciprocal heterozygotes produced by crossing wild-type plants to Pol IV mutants. We find that maternally and paternally acting Pol IV have divergent effects on endosperm. Losses of maternal and paternal Pol IV impact sRNAs and DNA methylation at distinct genomic sites. Strikingly, maternally and paternally-acting Pol IV have antagonistic impacts on gene expression at some loci, divergently promoting or repressing endosperm gene expression. Antagonistic parent-of origin effects have only rarely been described and are consistent with a gene regulatory system evolving under parental conflict
2022-03-04 | GSE197712 | GEO
Project description:24 nucleotide siRNAs are central players in RNA-directed DNA methylation (RdDM), a process that establishes DNA methylation at transposable elements to ensure genome stability. The plant-specific RNA polymerase IV (Pol IV) is required for siRNA biogenesis and is thought to transcribe RdDM loci to produce primary transcripts that serve as precursors to siRNAs. Yet, no such transcripts have ever been reported. Here, through RNA sequencing and double-stranded RNA sequencing in genotypes that compromise the dicing of siRNA precursors, we were able to identify Pol IV-dependent transcripts from tens of thousands of loci. We show that Pol IV-dependent transcripts correspond to both DNA strands, while the Pol II-dependent transcripts produced upon de-repression of the loci are derived from primarily one strand. We show that Pol IV-dependent transcripts have a 5â monophosphate, lack a polyA tail at the 3â end, and contain no introns; these features distinguish them from Pol II-dependent transcripts. Moreover, RDR2 is shown to play similar roles with Pol IV in both the abundance of siRNA precursors and siRNAs as well as the CHH DNA methylation. The decreased CHH methylation at dcl234 can inhibit the transcription of Pol IV at DRM2-target sites. Finally, the regulations of siRNA biogenesis were explored. To detect siRNA precursors transcribed by RNA polymerase IV, the genome wide profiling of RNA were carried out at dcl234 and dcl234 nrpd1. Different types of RNA (including Total RNA, polyA+ RNA, polyA- RNA, double stranded RNA) libraries were built to detect different transcripts. RDR2 is a RNA-dependent RNA polymerase in Pol IV complex, so the RNA-seq libraries with the mutation of RDR2 were also built. In addition, smRNA libraries with mutations blocking siRNA biogenesis were also built
2014-11-11 | E-GEOD-57215 | biostudies-arrayexpress
Project description:Knock down of RNA polymerase IV in rice caused pleiotropic reproductive defects. We investigated the molecular effects of loss of pol IV in different rice tissues by profiling sRNA and mRNA transcriptomes, DNA methylomes, histone modifications and degradome sequencing. These analyses revealed the multifaceted roles of RNA polymerase IV in bringing about regulation of protein coding genes.
2023-02-28 | GSE180312 | GEO