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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ABSTRACT:
ORGANISM(S): Schizosaccharomyces pombe
PROVIDER: GSE81326 | GEO | 2016/07/08
SECONDARY ACCESSION(S): PRJNA321294
REPOSITORIES: GEO
Similar Datasets
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: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:The CENP-B fission yeast homolog, ABP1, is involved in the repression of cryptic transcription from the Tf2 and rRNA genes repeat
| PRJNA321294 | ENA
Project description:It is well established that eukaryotic genomes are pervasively transcribed producing cryptic unstable transcripts (CUTs). However, the mechanisms regulating pervasive transcription are not well understood. Here, we report that the fission yeast CENP-B homolog Abp1 plays an important role in preventing pervasive transcription. We show that loss of abp1 results in the accumulation of CUTs, which are targeted for degradation by the exosome pathway. These CUTs originate from different types of genomic features, but the highest increase corresponds to Tf2 retrotransposons and rDNA repeats, where they map along the entire elements. In the absence of abp1, increased RNAPII-Ser5P occupancy is observed throughout the Tf2 coding region and, unexpectedly, RNAPII-Ser5P is enriched at rDNA repeats. Loss of abp1 also results in Tf2 derepression and increased nucleolus size. Altogether these results suggest that Abp1 prevents pervasive RNAPII transcription of repetitive DNA elements (i.e., Tf2 and rDNA repeats) from internal cryptic sites.
| S-EPMC5391875 | biostudies-literature
Project description:In fission yeast, mating-type switching involves replacing genetic information contained at the expressed mat1 locus by that of either the mat2P or mat3M donor loci. Donor selection is nonrandom, as mat1P cells preferentially use mat3M for switching, whereas mat1M cells use mat2P. Switching directionality is determined by the cell-type-specific distribution of the Swi2-Swi5 complex that, in mat1P cells, localises to mat3M and, only in mat1M cells, spreads to mat2P in a heterochromatin-dependent manner. Mechanisms regulating spreading of Swi2-Swi5 across heterochromatin are not fully understood. Here, we show that the fission yeast homologue of CENP-B, Abp1, binds to the silent domain of the mating-type locus and regulates directionality of switching. Deletion of abp1 prevents utilisation of mat2P, as when heterochromatin is disrupted and spreading of Swi2-Swi5 is impaired. Our results show that, indeed, deletion of abp1 abolishes spreading of Swi2-Swi5 to mat2P. However, in abp1Delta cells, heterochromatin organisation at the mating-type locus is preserved, indicating that Abp1 is actually required for efficient spreading of Swi2-Swi5 through heterochromatin. Cbh1 and Cbh2, which are also homologous to CENP-B, have only a minor contribution to the regulation of directionality of switching, which is in contrast with the strong effects observed for Abp1.
| S-EPMC2323252 | biostudies-literature
Project description:Microtubules are essential for a variety of fundamental cellular processes such as organelle positioning and control of cell shape. Schizosaccharomyces pombe is an ideal organism for studying the function and organization of microtubules into bundles in interphase cells. Using light microscopy and electron tomography we analyzed the bundle organization of interphase microtubules in S. pombe. We show that cells lacking ase1p and klp2p still contain microtubule bundles. In addition, we show that ase1p is the major determinant of inter-microtubule spacing in interphase bundles since ase1 deleted cells have an inter-microtubule spacing that differs from that observed in wild-type cells. We then identified dis1p, a XMAP215 homologue, as factor that promotes the stabilization of microtubule bundles. In wild-type cells dis1p partially co-localized with ase1p at regions of microtubule overlap. In cells deleted for ase1 and klp2, dis1p accumulated at the overlap regions of interphase microtubule bundles. In cells lacking all three proteins, both microtubule bundling and inter-microtubule spacing were further reduced, suggesting that Dis1p contributes to interphase microtubule bundling.
| S-EPMC2996303 | biostudies-literature
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 through not only the RNA interference (RNAi) machinery but also RNAi-independent RNA processing factors. Control of centromeric ncRNA transcription is therefore a key factor for proper centromere function. We here demonstrate that Mediator directs ncRNA transcription and regulates centromeric heterochromatin formation in fission yeast. Mediator colocalizes 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 via both the RNAi-dependent and -independent pathways, resulting in loss of CENP-A(Cnp1) from the core centromere, a defect in kinetochore function, and a severe chromosome segregation defect. Interestingly, the increased centromeric transcription observed in med20Δ cells appears to directly block CENP-A(Cnp1) incorporation since 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.
| S-EPMC3457525 | biostudies-literature
Project description:The centromere is a specific chromosomal locus that organizes the assembly of the kinetochore. It plays a fundamental role in accurate chromosome segregation. In most eukaryotic organisms, each chromosome contains a single centromere the position and function of which are epigenetically specified. Occasionally, centromeres form at ectopic loci, which can be detrimental to the cell. However, the mechanisms that protect the cell against ectopic centromeres (neocentromeres) remain poorly understood. Centromere protein-A (CENP-A), a centromere-specific histone 3 (H3) variant, is found in all centromeres and is indispensable for centromere function. Here we report that the overexpression of CENP-A(Cnp1) in fission yeast results in the assembly of CENP-A(Cnp1) at noncentromeric chromatin during mitosis and meiosis. The noncentromeric CENP-A preferentially assembles near heterochromatin and is capable of recruiting kinetochore components. Consistent with this, cells overexpressing CENP-A(Cnp1) exhibit severe chromosome missegregation and spindle microtubule disorganization. In addition, pulse induction of CENP-A(Cnp1) overexpression reveals that ectopic CENP-A chromatin can persist for multiple generations. Intriguingly, ectopic assembly of CENP-A(cnp1) is suppressed by overexpression of histone H3 or H4. Finally, we demonstrate that deletion of the N-terminal domain of CENP-A(cnp1) results in an increase in the number of ectopic CENP-A sites and provide evidence that the N-terminal domain of CENP-A prevents CENP-A assembly at ectopic loci via the ubiquitin-dependent proteolysis. These studies expand our current understanding of how noncentromeric chromatin is protected from mistakenly assembling CENP-A.
| S-EPMC4256763 | biostudies-literature
Project description:CENP-A is a centromere-specific histone H3 variant that is essential for kinetochore formation. Here, we report that the fission yeast Schizosaccharomyces pombe has at least two distinct CENP-A deposition phases across the cell cycle: S and G2. The S phase deposition requires Ams2 GATA factor, which promotes histone gene activation. In Delta ams2, CENP-A fails to retain during S, but it reaccumulates onto centromeres via the G2 deposition pathway, which is down-regulated by Hip1, a homologue of HIRA histone chaperon. Reducing the length of G2 in Delta ams2 results in failure of CENP-A accumulation, leading to chromosome missegregation. N-terminal green fluorescent protein-tagging reduces the centromeric association of CENP-A, causing cell death in Delta ams2 but not in wild-type cells, suggesting that the N-terminal tail of CENP-A may play a pivotal role in the formation of centromeric nucleosomes at G2. These observations imply that CENP-A is normally localized to centromeres in S phase in an Ams2-dependent manner and that the G2 pathway may salvage CENP-A assembly to promote genome stability. The flexibility of CENP-A incorporation during the cell cycle may account for the plasticity of kinetochore formation when the authentic centromere is damaged.
| S-EPMC2230595 | biostudies-literature