scholarly journals Intronic heterochromatin prevents cryptic transcription initiation in Arabidopsis

2019 ◽  
Author(s):  
Jincong Zhou ◽  
Liangyu Liu ◽  
Qin Li ◽  
Wei Xu ◽  
Kuan Li ◽  
...  

ABSTRACTIntronic transposable elements (TEs) comprise a large proportion in eukaryotic genomes, but how they regulate the host genes remains to be explored. Our forward genetic screen disclosed the plant specific RNA polymerases IV and V in suppressing intronic TE-mediated cryptic transcription initiation of a chimeric transcripts at FLC (FLCTE). Initiation of FLCTE transcription is blocked by the locally formed intronic heterochromatin, which is directly associated with RNA Pol V to inhibit the entry of RNA Pol II and the occupancy of H3K4 methylation. Genome-wide Pol II Ser5p native elongation transcription sequencing revealed that this is a common mechanism among intronic heterochromatin-containing genes. This study sheds light on deeply understanding the function of intronic heterochromatin on host genes expression in eukaryotic genome.

2018 ◽  
Author(s):  
Emma Briggs ◽  
Graham Hamilton ◽  
Kathryn Crouch ◽  
Craig Lapsley ◽  
Richard McCulloch

AbstractR-loops are stable RNA-DNA hybrids that have been implicated in transcription initiation and termination, as well as in telomere homeostasis, chromatin formation, and genome replication and instability. RNA Polymerase (Pol) II transcription in the protozoan parasite Trypanosoma brucei is highly unusual: virtually all genes are co-transcribed from multigene transcription units, with mRNAs generated by linked trans-splicing and polyadenylation, and transcription initiation sites display no conserved promoter motifs. Here, we describe the genome-wide distribution of R-loops in wild type mammal-infective T. brucei and in mutants lacking RNase H1, revealing both conserved and diverged functions. Conserved localisation was found at centromeres, rRNA genes and retrotransposon-associated genes. RNA Pol II transcription initiation sites also displayed R-loops, suggesting a broadly conserved role despite the lack of promoter conservation or transcription initiation regulation. However, the most abundant sites of R-loop enrichment were within the intergenic regions of the multigene transcription units, where the hybrids coincide with sites of polyadenylation and nucleosome-depletion. Thus, instead of functioning in transcription termination, most T. brucei R-loops act in a novel role, promoting RNA Pol II movement or mRNA processing. Finally, we show there is little evidence for correlation between R-loop localisation and mapped sites of DNA replication initiation.


2010 ◽  
Vol 39 (1) ◽  
pp. 190-201 ◽  
Author(s):  
Hao Sun ◽  
Jiejun Wu ◽  
Priyankara Wickramasinghe ◽  
Sharmistha Pal ◽  
Ravi Gupta ◽  
...  

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Anand Ranjan ◽  
Vu Q Nguyen ◽  
Sheng Liu ◽  
Jan Wisniewski ◽  
Jee Min Kim ◽  
...  

The H2A.Z histone variant, a genome-wide hallmark of permissive chromatin, is enriched near transcription start sites in all eukaryotes. H2A.Z is deposited by the SWR1 chromatin remodeler and evicted by unclear mechanisms. We tracked H2A.Z in living yeast at single-molecule resolution, and found that H2A.Z eviction is dependent on RNA Polymerase II (Pol II) and the Kin28/Cdk7 kinase, which phosphorylates Serine 5 of heptapeptide repeats on the carboxy-terminal domain of the largest Pol II subunit Rpb1. These findings link H2A.Z eviction to transcription initiation, promoter escape and early elongation activities of Pol II. Because passage of Pol II through +1 nucleosomes genome-wide would obligate H2A.Z turnover, we propose that global transcription at yeast promoters is responsible for eviction of H2A.Z. Such usage of yeast Pol II suggests a general mechanism coupling eukaryotic transcription to erasure of the H2A.Z epigenetic signal.


2018 ◽  
Author(s):  
Constantine Mylonas ◽  
Peter Tessarz

ABSTRACTThe advent of quantitative approaches that enable interrogation of transcription at single nucleotide resolution has allowed a novel understanding of transcriptional regulation previously undefined. However, little is known, at such high resolution, how transcription factors directly influence RNA Pol II pausing and directionality. To map the impact of transcription/elongation factors on transcription dynamics genome-wide at base pair resolution, we developed an adapted NET-seq protocol called NET-prism (Native Elongating Transcription by Polymerase-Regulated Immunoprecipitants in the Mammalian genome). Application of NET-prism on elongation factors (Spt6, Ssrp1), splicing factors (Sf1), and components of the pre-initiation complex (PIC) (TFIID, and Mediator) reveals their inherent command on transcription dynamics, with regards to directionality and pausing over promoters, splice sites, and enhancers/super-enhancers. NET-prism will be broadly applicable as it exposes transcription factor/Pol II dependent topographic specificity and thus, a new degree of regulatory complexity during gene expression.


2018 ◽  
Vol 9 ◽  
Author(s):  
Michael W. Krause ◽  
Dona C. Love ◽  
Salil K. Ghosh ◽  
Peng Wang ◽  
Sijung Yun ◽  
...  
Keyword(s):  
Pol Ii ◽  

Author(s):  
Ophir Shalem ◽  
Bella Groisman ◽  
Mordechai Choder ◽  
Orna Dahan ◽  
Yitzhak Pilpel
Keyword(s):  
Pol Ii ◽  

2019 ◽  
Vol 47 (17) ◽  
pp. 9180-9197 ◽  
Author(s):  
Emma Briggs ◽  
Kathryn Crouch ◽  
Leandro Lemgruber ◽  
Graham Hamilton ◽  
Craig Lapsley ◽  
...  

Abstract Ribonucleotides represent a threat to DNA genome stability and transmission. Two types of Ribonuclease H (RNase H) excise ribonucleotides when they form part of the DNA strand, or hydrolyse RNA when it base-pairs with DNA in structures termed R-loops. Loss of either RNase H is lethal in mammals, whereas yeast survives the absence of both enzymes. RNase H1 loss is tolerated by the parasite Trypanosoma brucei but no work has examined the function of RNase H2. Here we show that loss of T. brucei RNase H2 (TbRH2A) leads to growth and cell cycle arrest that is concomitant with accumulation of nuclear damage at sites of RNA polymerase (Pol) II transcription initiation, revealing a novel and critical role for RNase H2. Differential gene expression analysis reveals limited overall changes in RNA levels for RNA Pol II genes after TbRH2A loss, but increased perturbation of nucleotide metabolic genes. Finally, we show that TbRH2A loss causes R-loop and DNA damage accumulation in telomeric RNA Pol I transcription sites, also leading to altered gene expression. Thus, we demonstrate separation of function between two nuclear T. brucei RNase H enzymes during RNA Pol II transcription, but overlap in function during RNA Pol I-mediated gene expression during host immune evasion.


BMC Genomics ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Adam Scheidegger ◽  
Carissa J. Dunn ◽  
Ann Samarakkody ◽  
Nii Koney-Kwaku Koney ◽  
Danielle Perley ◽  
...  

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