Project description:The TE-Seq pipeline conducts an end-to-end analysis of RNA sequencing data, examining both genes and TEs. It implements the most current computational methods tailor-made for TEs, and produces a comprehensive analysis of TE expression at both the level of the individual element and at the TE clade level. Furthermore, if supplied with long-read DNA sequencing data, it is able to assess TE expression from non-reference (polymorphic) loci. As a demonstration, we analyzed proliferating, early senescent, and late senescent lung fibroblast RNA-Seq data, and created a custom reference genome and annotations for this cell strain using Nanopore sequencing data. We found that several retrotransposable element (RTE) clades were upregulated in senescence, which included non-reference, intact, and potentially active elements.
Project description:Investigation of the effect of the knockdown of AT-hook motif DNA binding nuclear matrix protein TRANSPOSABLE ELEMENT KILLER (TEK) in the Arabidopsis Landsberg erecta (Ler) background Transposable elements (TEs) are silenced by epigenetic mechanisms of DNA and histone methylation. The repressive histone modification H3 lysine 9 dimethylation (H3K9me2) is TE-associated epigenetic hallmark, and is necessary for DNA methylation. However the mechanism to direct the repressive epigenetic modification in TEs has remained elusive. Here we show that knockdown of the AT-hook motif DNA binding nuclear matrix protein TRANSPOSABLE ELEMENT KILLER (TEK) in the Arabidopsis Landsberg erecta (Ler) background results in robust activation of various TEs, the repeat-containing floral repressor gene FWA and the TE-containing floral repressor FLOWERING LOCUS C (FLC). A four chip study using two separate wild-type seedling mRNA samples and two separate TEKi seedling mRNA samples
Project description:We have used the genetic resources of Arabidopsis thaliana to generate mutant lines that have reactivated TE expression. We used these lines with long-read Oxford Nanopore sequencing technology to capture Transposable Element (TE) mRNAs for TE transcript annotation.
Project description:Transposable elements (TEs) are self-mobilizing elements that make up a large fraction of mammalian genomes. PIWI proteins and PIWI interacting RNAs (piRNAs) are a part of a system aimed at controlling and preventing TE proliferation. We examined the TE landscape and piRNA repertoires from three non-model Laurasiatherian mammals (dog, horse and big brown bat) with differing TE complements and proliferation patterns to address questions about the evolutionary relationships between piRNAs and TEs. We found that the genomic abundance of new TEs may not match TE transcription. We speculate that a higher rate of SINE targeting by piRNAs in the horse genome contributed to the reduced SINE insertion rate.
Project description:Background: The small RNAs that Transposable Elements generate are vastly different when they are transcriptionally silenced compared to when they are transcriptionally activated. We performed the deep sequencing of small RNAs in a number of small RNA biogenesis mutants in both Transposable Element-silenced and Transposable Element-active epigenome backgrounds. Results: We found that Transposable Elements generate large amounts of 21-22nt siRNAs only when they are transcriptionally active. These 21-22nt siRNAs are incorporated into the AGO6 protein. Conclusion: Ago6 is the key protein that bridges the post-transcriptional degradation of Transposable Element mRNAs and the establishment of DNA methylation. Examination of flower bud small RNAs from wild type and 5 single or double mutant combinations, many of which have biological replicates. In addition, IP purification of the AGO6 protein (and mock no-antigen controls) followed by sequencing of the incorporated small RNAs. Replicate A for Col and ddm1 are submitted in GSE41755
Project description:Investigation of the effect of the knockdown of AT-hook motif DNA binding nuclear matrix protein TRANSPOSABLE ELEMENT KILLER (TEK) in the Arabidopsis Landsberg erecta (Ler) background Transposable elements (TEs) are silenced by epigenetic mechanisms of DNA and histone methylation. The repressive histone modification H3 lysine 9 dimethylation (H3K9me2) is TE-associated epigenetic hallmark, and is necessary for DNA methylation. However the mechanism to direct the repressive epigenetic modification in TEs has remained elusive. Here we show that knockdown of the AT-hook motif DNA binding nuclear matrix protein TRANSPOSABLE ELEMENT KILLER (TEK) in the Arabidopsis Landsberg erecta (Ler) background results in robust activation of various TEs, the repeat-containing floral repressor gene FWA and the TE-containing floral repressor FLOWERING LOCUS C (FLC).
Project description:Background: The small RNAs that Transposable Elements generate are vastly different when they are transcriptionally silenced compared to when they are transcriptionally activated. We performed the deep sequencing of small RNAs in a number of small RNA biogenesis mutants in both Transposable Element-silenced and Transposable Element-active epigenome backgrounds. Results: We found that Transposable Elements generate large amounts of 21-22nt siRNAs only when they are transcriptionally active. These 21-22nt siRNAs are incorporated into the AGO6 protein. Conclusion: Ago6 is the key protein that bridges the post-transcriptional degradation of Transposable Element mRNAs and the establishment of DNA methylation.
Project description:Background: Transposable element 24 nucleotide small RNAs are not efficiently incorporated into the AGO1 protein, which is involved in endogenous RNAi and gene regulation through the microRNA and tasiRNA pathways. Results: The AGO1 protein incorporates large quantities of transposable element siRNAs when transposable elements are epigenetically activated and transcribed. The incorporation of transposable element siRNAs is at the expense of the most abundant microRNAs. These transposable element siRNAs can act as tasiRNAs, regulating genes that they have partial complementarity to. Conclusion: Transposable element small RNAs are more dynamic than previously thought. They can be incorporated into AGO1 and regulate genes. Three biological replicates of small RNA sequencing from two genotypes
Project description:Background: Eukaryotic organisms have evolved a series of mechanisms to regulate transposable element (TE) expression based on RNA silencing. In plants, the initial step in the recognition of TE transcripts relies on microRNAs, but this is unlikely to take place in the pollen grain where natural reactivation of TE transcription occurs but microRNAs accumulate to low levels. We investigated small non-coding RNA accumulation in plants and found conserved tRNA-derived RNA fragment (tRF) accumulation in the pollen grain or analogous reproductive structure in a variety of plant species. Results:Analysis of tRF biology in Arabidopsis revealed that tRFs are regulated by the chromatin modifier DDM1, have a microRNA-like biogenesis pathway, and specifically target TE mRNAs. In addition, we provide evidence that tRF targeting is involved in the production of secondary small RNAs derived from TE transcripts, which initiate a cascade of RNAi and TE silencing. Conclusion:that tRFs are bona-fide regulatory microRNA-like small RNAs involved in the regulation of genome stability through the targeting of TE transcripts.