The CENP-B fission yeast homolog, ABP1, is involved in the repression of cryptic transcription from the Tf2 and rRNA genes repeat
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PROVIDER: PRJNA321294 | ENA |
REPOSITORIES: ENA
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Project description:In Schizosaccharomyces pombe, Abp1 is homologous to mammalian CENP-B. Abp1 has various seemingly independent functions in the yeast nucleus. It binds to pericentromeric repeats and contribute to heterochromatin formation (ref). Abp1 is involved in regulating the directionality of mating-type switching by regulating the transcription of a member of the recombination-promoting complex (refs). Abp1 also preserves genome integrity by silencing the Tf2 retrotransposons and protecting replication forks during pausing (ref). The profile of the RNA extracted from abp1Δ cells shows an accumulation of RNA in size ranging between 100 and 200 bp. Solexa sequencing of these “little RNA” (liRNA) and comparison of their levels with the WT showed an increase in liRNA coming from various classes of genomic features. The biggest fold changes are attributed to liRNA coming from LTR retrotransposons and the rDNA genes repeats. We show that these liRNAs are targeted for degradation by the exosome and are the products of pervasive RNA Polymerase II transcription. Finally, we describe the genetic interactions of various transcriptional gene silencing effectors with the abp1 deletion in the silencing of the liRNA.
2016-07-08 | GSE81280 | GEO
Project description:In Schizosaccharomyces pombe, Abp1 is homologous to mammalian CENP-B. Abp1 has various seemingly independent functions in the yeast nucleus. It binds to pericentromeric repeats and contribute to heterochromatin formation (ref). Abp1 is involved in regulating the directionality of mating-type switching by regulating the transcription of a member of the recombination-promoting complex (refs). Abp1 also preserves genome integrity by silencing the Tf2 retrotransposons and protecting replication forks during pausing (ref). The profile of the RNA extracted from abp1Δ cells shows an accumulation of RNA in size ranging between 100 and 200 bp. Solexa sequencing of these “little RNA” (liRNA) and comparison of their levels with the WT showed an increase in liRNA coming from various classes of genomic features. The biggest fold changes are attributed to liRNA coming from LTR retrotransposons and the rDNA genes repeats. We show that these liRNAs are targeted for degradation by the exosome and are the products of pervasive RNA Polymerase II transcription. Finally, we describe the genetic interactions of various transcriptional gene silencing effectors with the abp1 deletion in the silencing of the liRNA.
2016-07-08 | GSE81324 | GEO
Project description:In Schizosaccharomyces pombe, Abp1 is homologous to mammalian CENP-B. Abp1 has various seemingly independent functions in the yeast nucleus. It binds to pericentromeric repeats and contribute to heterochromatin formation (ref). Abp1 is involved in regulating the directionality of mating-type switching by regulating the transcription of a member of the recombination-promoting complex (refs). Abp1 also preserves genome integrity by silencing the Tf2 retrotransposons and protecting replication forks during pausing (ref). The profile of the RNA extracted from abp1Δ cells shows an accumulation of RNA in size ranging between 100 and 200 bp. Solexa sequencing of these “little RNA” (liRNA) and comparison of their levels with the WT showed an increase in liRNA coming from various classes of genomic features. The biggest fold changes are attributed to liRNA coming from LTR retrotransposons and the rDNA genes repeats. We show that these liRNAs are targeted for degradation by the exosome and are the products of pervasive RNA Polymerase II transcription. Finally, we describe the genetic interactions of various transcriptional gene silencing effectors with the abp1 deletion in the silencing of the liRNA.
2016-07-08 | GSE81323 | GEO
Project description:Expression profiling of mutant cells compared to wild-type cells. Expression profiling of S. pombe CENP-B homolog cbp1∆ (abp1/SPBC1105.04c) and histone deacetylase double mutant clr3∆ clr6-1 (SPBC800.03 SPBC36.05c) cells.
2012-10-12 | GSE39404 | GEO
Project description:Expression profiling of mutant cells compared to wild-type cells. Expression profiling of S. pombe CENP-B homolog cbp1M-bM-^HM-^F (abp1/SPBC1105.04c) and histone deacetylase double mutant clr3M-bM-^HM-^FM-BM- clr6-1 (SPBC800.03 SPBC36.05c) cells. Wildtype and mutant cDNA was reverse transcribed from total RNA using the Invitrogen SuperscriptIII Indirect labeling kit and the supplied anchored oligo-dT according to the manufacturer's instructions. cDNA from mutant and wildtype samples were labeled with Alexa Fluor 555 and 647 dyes, respectively. Biological duplicates were performed for each mutant and wildtype sample. An Agilent 44K in situ 60mer DNA microarray that tiles the entire Schizosaccharomyces pombe genome every 300 bp alternately on both strands was used to probe expression of transcripts in CENP-B homolog cbp1M-bM-^HM-^F (abp1/SPBC1105.04c) and histone deacetylase double mutants clr3M-bM-^HM-^F clr6-1 (SPBC800.03 SPBC36.05c) cells versus wildtype.
2012-10-12 | E-GEOD-39404 | biostudies-arrayexpress
Project description:This SuperSeries is composed of the following subset Series: GSE32310: Transcriptome analysis of mediator Med20 mutant and dcr1 mutant in S.pombe GSE35524: Mediator promotes CENP-A incorporation at fission yeast centromeres [ChIP-seq] Refer to individual Series
2012-11-06 | E-GEOD-35527 | biostudies-arrayexpress
Project description:We employ the well-studied fission yeast centromere to investigate the function of the CENP-A (Cnp1) N-tail. We show that alteration of the N-tail did not affect Cnp1 loading at centromeres, outer kinetochore formation, or spindle checkpoint signaling, but nevertheless elevated chromosome loss. N-Tail mutants exhibited synthetic lethality with an altered centromeric DNA sequence, with rare survivors harboring chromosomal fusions in which the altered centromere was epigenetically inactivated. Elevated centromere inactivation was also observed for N-tail mutants with unaltered centromeric DNA sequences. N-tail mutants specifically reduced localization of the CCAN proteins Cnp20/CENP-T and Mis6/CENP-I, but not Cnp3/CENP-C. Overexpression of Cnp20/CENP-T suppressed defects in an N-tail mutant, suggesting a causal link between reduced CENP-T recruitment and the observed centromere inactivation phenotype. Thus, the Cnp1 N-tail promotes epigenetic stability of centromeres via recruitment of the CENP-T branch of the CCAN.
2015-04-16 | GSE63350 | GEO
Project description:We employ the well-studied fission yeast centromere to investigate the function of the CENP-A (Cnp1) N-tail. We show that alteration of the N-tail did not affect Cnp1 loading at centromeres, outer kinetochore formation, or spindle checkpoint signaling, but nevertheless elevated chromosome loss. N-Tail mutants exhibited synthetic lethality with an altered centromeric DNA sequence, with rare survivors harboring chromosomal fusions in which the altered centromere was epigenetically inactivated. Elevated centromere inactivation was also observed for N-tail mutants with unaltered centromeric DNA sequences. N-tail mutants specifically reduced localization of the CCAN proteins Cnp20/CENP-T and Mis6/CENP-I, but not Cnp3/CENP-C. Overexpression of Cnp20/CENP-T suppressed defects in an N-tail mutant, suggesting a causal link between reduced CENP-T recruitment and the observed centromere inactivation phenotype. Thus, the Cnp1 N-tail promotes epigenetic stability of centromeres via recruitment of the CENP-T branch of the CCAN. Genome-wide localization of GFP-tagged N-tail Cnp1 variant tailswap versus wt control in cnp1 deletion background
2015-04-16 | E-GEOD-63350 | biostudies-arrayexpress
Project description:At Schizosaccharomyces pombe centromeres, heterochromatin formation is required for de novo incorporation of the histone H3 variant CENP-A/Cnp1, which in turn directs kinetochore assembly and ultimately chromosome segregation during mitosis. Noncoding RNAs (ncRNAs) transcribed by RNA polymerase II (Pol II) directs heterochromatin formation via the RNAi machinery, but also through RNAiindependent RNA processing factors. Control of centromeric ncRNA transcription is therefore a key factor for proper centromere function. We here use transcriptional profiling, gene inactivation experiments, and chromatin immunoprecipitation analyses to demonstrate that the Mediator complex directs ncRNA transcription and regulates centromeric heterochromatin formation in fission yeast. Mediator co-localizes with Pol II at centromeres and loss of the Mediator subunit Med20 causes a dramatic increase in pericentromeric transcription and desilencing of the core centromere. As a consequence, heterochromatin formation is impaired both via the RNAi dependent and independent pathways, resulting in loss of CENP-A/Cnp1 from the core centromere, defect kinetochore function, and a severe chromosome segregation defect. Interestingly, the increased centromeric transcription observed in med20Δ appears to directly block CENP-A/Cnp1 incorporation and inhibition of Pol II transcription can suppress the observed phenotypes. Our data thus identify Mediator as a crucial regulator of ncRNA transcription at fission yeast centromeres and add another crucial layer of regulation to centromere function.
2012-11-06 | GSE35524 | GEO
Project description:Specialized chromatin containing CENP-A nucleosomes instead of H3 nucleosomes is found at all centromeres. However, the mechanisms that specify the locations at which CENP-A chromatin is assembled remain elusive in organisms with regional, epigenetically regulated centromeres. It is known that normal centromeric DNA is transcribed in several systems including the fission yeast, Schizosaccharomyces pombe. Here, we show that factors which preserve stable histone H3 chromatin during transcription also play a role in preventing promiscuous CENP-A(Cnp1) deposition in fission yeast. Mutations in the histone chaperone FACT impair the maintenance of H3 chromatin on transcribed regions and promote widespread CENP-A(Cnp1) incorporation at non-centromeric sites. FACT has little or no effect on CENP-A(Cnp1) assembly at endogenous centromeres where CENP-A(Cnp1) is normally assembled. In contrast, Clr6 complex II (Clr6-CII; equivalent to Rpd3S) histone deacetylase function has a more subtle impact on the stability of transcribed H3 chromatin and acts to prevent the ectopic accumulation of CENP-A(Cnp1) at specific loci, including subtelomeric regions, where CENP-A(Cnp1) is preferentially assembled. Moreover, defective Clr6-CII function allows the de novo assembly of CENP-A(Cnp1) chromatin on centromeric DNA, bypassing the normal requirement for heterochromatin. Thus, our analyses show that alterations in the process of chromatin assembly during transcription can destabilize H3 nucleosomes and thereby allow CENP-A(Cnp1) to assemble in its place. We propose that normal centromeres provide a specific chromatin context that limits reassembly of H3 chromatin during transcription and thereby promotes the establishment of CENP-A(Cnp1) chromatin and associated kinetochores. These findings have important implications for genetic and epigenetic processes involved in centromere specification. In total, 24 samples: 22 ChIP DNA files (10 different conditions), 2 Input files.
2015-02-19 | E-GEOD-66106 | biostudies-arrayexpress