Two components of the RNA-directed DNA methylation pathway associate with MORC6 and silence loci targeted by MORC6 in Arabidopsis
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ABSTRACT:
ORGANISM(S): Arabidopsis thaliana
PROVIDER: GSE80370 | GEO | 2016/04/19
SECONDARY ACCESSION(S): PRJNA318748
REPOSITORIES: GEO
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Project description:The Microrchidia (MORC) family of ATPases are required for transposable element (TE) silencing and heterochromatin condensation in plants and animals, and C. elegans MORC-1 has been shown to topologically entrap and condense DNA. In Arabidopsis thaliana, mutation of MORCs has been shown to reactivate silent methylated genes and transposons and to decondense heterochromatic chromocenters, despite only minor changes in the maintenance of DNA methylation. Here we provide the first evidence localizing Arabidopsis MORC proteins to specific regions of chromatin and find that MORC4 and MORC7 are closely co-localized with sites of RNA directed DNA methylation (RdDM). We further show that MORC7, when tethered to DNA by an artificial zinc finger, can facilitate the establishment of RdDM. Finally, we show that MORCs are required for the efficient RdDM mediated establishment of DNA methylation and silencing of a newly integrated FWA transgene, even though morc mutations have no effect on the maintenance of preexisting methylation at the endogenous FWA gene. We propose that MORCs function as a molecular tether in RdDM complexes to reinforce RdDM activity for methylation establishment. These findings have implications for MORC protein function in a variety of other eukaryotic organisms.
2021-07-02 | PXD026674 | Pride
Project description:The Microrchidia (MORC) family of ATPases are required for transposable element (TE) silencing and heterochromatin condensation in plants and animals, and C. elegans MORC-1 has been shown to topologically entrap and condense DNA. In Arabidopsis thaliana, mutation of MORCs has been shown to reactivate silent methylated genes and transposons and to decondense heterochromatic chromocenters, despite only minor changes in the maintenance of DNA methylation. Here we provide the first evidence localizing Arabidopsis MORC proteins to specific regions of chromatin and find that MORC4 and MORC7 are closely co-localized with sites of RNA directed DNA methylation (RdDM). We further show that MORC7, when tethered to DNA by an artificial zinc finger, can facilitate the establishment of RdDM. Finally, we show that MORCs are required for the efficient RdDM mediated establishment of DNA methylation and silencing of a newly integrated FWA transgene, even though morc mutations have no effect on the maintenance of preexisting methylation at the endogenous FWA gene. We propose that MORCs function as a molecular tether in RdDM complexes to reinforce RdDM activity for methylation establishment. These findings have implications for MORC protein function in a variety of other eukaryotic organisms.
2021-07-02 | GSE160285 | GEO
Project description:Transposable elements (TEs) and DNA repeats are commonly targeted by DNA and histone methylation to achieve epigenetic gene silencing. We isolated mutations in two Arabidopsis genes, CRT1 and CRH6, which cause de-repression of DNA-methylated genes and TEs, but no losses of DNA or histone methylation. CRT1 and CRH6 are members of the conserved Microrchidia (MORC) ATPase family, predicted to catalyze alterations in chromosome superstructure. The crt1 and crh6 mutants show decondensation of pericentromeric heterochromatin, increased interaction of pericentromeric regions with the rest of the genome, and transcriptional defects that are largely restricted to loci residing in pericentromeric regions. Knockdown of the single MORC homolog in Caenorhabditis elegans also impairs transgene silencing. We propose that the MORC ATPases are conserved regulators of gene silencing in eukaryotes. For Col wild type control and each of two T-DNA mutants, a single sample each of small RNA (sRNA), mRNA-Seq, 5'-methylcytosine DNA methylation (BS-Seq), ChIP H3K9me2 histone methylation, and ChIP H3 histone control. For each of two EMS mutants, and as controls, their respective backgrounds, two batches of single mRNA samples, with the first batch also having a single mRNA sample for a double EMS mutant.
2012-05-02 | E-GEOD-37644 | biostudies-arrayexpress
Project description:Transposable elements (TEs) and DNA repeats are commonly targeted by DNA and histone methylation to achieve epigenetic gene silencing. We isolated mutations in two Arabidopsis genes, CRT1 and CRH6, which cause de-repression of DNA-methylated genes and TEs, but no losses of DNA or histone methylation. CRT1 and CRH6 are members of the conserved Microrchidia (MORC) ATPase family, predicted to catalyze alterations in chromosome superstructure. The crt1 and crh6 mutants show decondensation of pericentromeric heterochromatin, increased interaction of pericentromeric regions with the rest of the genome, and transcriptional defects that are largely restricted to loci residing in pericentromeric regions. Knockdown of the single MORC homolog in Caenorhabditis elegans also impairs transgene silencing. We propose that the MORC ATPases are conserved regulators of gene silencing in eukaryotes.
2012-05-03 | GSE37644 | GEO
Project description:Epigenetic gene silencing is of central importance to maintain genome integrity and is mediated by an elaborate interplay between DNA methylation, histone posttranslational modifications and chromatin remodeling complexes. DNA methylation and repressive histone marks usually correlate with transcriptionally silent heterochromatin, however there are exceptions to this interdependence. In Arabidopsis, mutation of MORPHEUS MOLECULE 1 (MOM1) causes transcriptional derepression of heterochromatin independently of changes in DNA methylation. More recently, two Arabidopsis homologs of mouse Microrchidia (MORC) have also been implicated in gene silencing and heterochromatin condensation without altering genome-wide DNA methylation patterns. In this study, we show that AtMORC6 physically interacts with AtMORC1 and with its close homologue AtMORC2 in two mutually exclusive protein complexes. RNA-seq analysis of high-order mutants indicates that AtMORC1 and AtMORC2 act redundantly to repress a common set of loci. We also examined the genetic interactions between AtMORC6 and MOM1 pathways. Although AtMORC6 and MOM1 control the silencing of a very similar set of genomic loci, we observed synergistic transcriptional regulation in the mom1/atmorc6 double mutant, suggesting that these epigenetic regulators act mainly by independent silencing mechanisms.
2014-06-01 | GSE54677 | GEO
Project description:Epigenetic gene silencing is of central importance to maintain genome integrity and is mediated by an elaborate interplay between DNA methylation, histone posttranslational modifications and chromatin remodeling complexes. DNA methylation and repressive histone marks usually correlate with transcriptionally silent heterochromatin, however there are exceptions to this interdependence. In Arabidopsis, mutation of MORPHEUS MOLECULE 1 (MOM1) causes transcriptional derepression of heterochromatin independently of changes in DNA methylation. More recently, two Arabidopsis homologs of mouse Microrchidia (MORC) have also been implicated in gene silencing and heterochromatin condensation without altering genome-wide DNA methylation patterns. In this study, we show that AtMORC6 physically interacts with AtMORC1 and with its close homologue AtMORC2 in two mutually exclusive protein complexes. RNA-seq analysis of high-order mutants indicates that AtMORC1 and AtMORC2 act redundantly to repress a common set of loci. We also examined the genetic interactions between AtMORC6 and MOM1 pathways. Although AtMORC6 and MOM1 control the silencing of a very similar set of genomic loci, we observed synergistic transcriptional regulation in the mom1/atmorc6 double mutant, suggesting that these epigenetic regulators act mainly by independent silencing mechanisms. RNA-seq libraries were prepared for two suites of mutants to allow direct comparisons between mutants within each set. The two sets consisted of the following samples: Set_1) A wildtype (Col) control, the morc1 mutant, the morc2 mutant, the morc1 morc2 double mutant, the morc6 mutant, and the morc1 morc2 morc6 triple mutant ; Set_2) A wildtpe (Col) control, the morc6 mutant, the mom1 mutant, and the mom1 morc6 double mutant. For each sample, two biological replicates were performed (denoted "bio_replicate_1" or "bio_replicate_2"). Whole genome bisulifte libraries were sequenced from material grown in parallel.
2014-06-01 | E-GEOD-54677 | biostudies-arrayexpress
Project description:The Microrchidia (MORC) family proteins are evolutionarily conserved GHKL type ATPases involved in chromatin compaction and gene silencing. Arabidopsis MORC proteins act in the RNA-directed DNA methylation (RdDM) pathway where they act as molecular tethers to ensure the efficient establishment of RdDM and de novo gene silencing. However, they also have RdDM independent functions in which the underlying mechanism is unknown. In this study, we examined MORC binding regions that are devoid of RdDM to shed light on MORCs RdDM independent functions. We found that MORC proteins can compact chromatin, exclude the accessibility of DNA to transcription factors (TFs) and thereby repress gene expression. We also found that MORC-mediated repression is particularly important under stress conditions. In addition, we showed that MORC proteins may regulate TFs through direct or indirect interactions. These TFs in turn regulate their own transcription, indicating a feedforward loop. Our findings provide insights into the molecular mechanisms of MORC-mediated chromatin compaction and transcription regulation.
2023-03-27 | GSE212801 | GEO
Project description:The Microrchidia (Morc) family of GHKL ATPases are present in a wide variety of prokaryotic and eukaryotic organisms but are of largely unknown function. Genetic screens in Arabidopsis thaliana have identified Morc genes as important repressors of transposons and other DNA methylated and silent genes. MORC1 deficient mice were previously found to display male-specific germ cell loss and infertility. Here we show that MORC1 is responsible for transposon repression in the male germline in a pattern that is similar to that observed for germ cells deficient for the DNA methyltransferase homolog DNMT3L. Morc1 mutants show highly localized defects in the establishment of DNA methylation at specific classes of transposons, and this is associated with failed transposon silencing at these sites. Our results identify MORC1 as an important new regulator of the epigenetic landscape of male germ cells during the period of global de novo methylation. This data includes: 47 RNA-seq, 4 smRNA-seq, 6 BS-seq, and 2 ChIP-seq datasets
2014-12-12 | E-GEOD-63048 | biostudies-arrayexpress
Project description:MORC family ATPases required for heterochromatin condensation and gene silencing
| PRJNA162669 | ENA
Project description:The MORC family of GHKL ATPases are an enigmatic class of proteins with diverse chromatin related functions. In Arabidopsis, AtMORC1, AtMORC2, and AtMORC6 act together in heterodimeric complexes to mediate transcriptional silencing of methylated DNA elements. Here, we studied Arabidopsis AtMORC4 and AtMORC7. We found that, in contrast to AtMORC1,2,6, they act to suppress a wide set of non-methylated protein-coding genes that are enriched for those involved in pathogen response. Furthermore, atmorc4 atmorc7 double mutants show a pathogen response phenotype. We found that AtMORC4 and AtMORC7 form homomeric complexes in vivo and are concentrated in discrete nuclear bodies adjacent to chromocenters. Analysis of an atmorc1,2,4,5,6,7 hextuple mutant demonstrates that transcriptional de-repression is largely uncoupled from changes in DNA methylation in plants devoid of MORC function. However, we also uncover a requirement for MORC in both DNA methylation and silencing at a small but distinct subset of RNA-directed DNA methylation target loci. These regions are characterized by poised transcriptional potential and a low density of sites for symmetric cytosine methylation. These results provide insights into the biological function of MORC proteins in higher eukaryotes.
2016-05-11 | GSE78836 | GEO