Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

The fission yeast heterochromatin protein Rik1 is required for telomere clustering during meiosis.

ABSTRACT: Telomeres share the ability to silence nearby transcription with heterochromatin, but the requirement of heterochromatin proteins for most telomere functions is unknown. The fission yeast Rik1 protein is required for heterochromatin formation at centromeres and the mating-type locus, as it recruits the Clr4 histone methyltransferase, whose modification of histone H3 triggers binding by Swi6, a conserved protein involved in spreading of heterochromatin. Here, we demonstrate that Rik1 and Clr4, but not Swi6, are required along with the telomere protein Taz1 for crucial chromosome movements during meiosis. However, Rik1 is dispensable for the protective roles of telomeres in preventing chromosome end-fusion. Thus, a Swi6-independent heterochromatin function distinct from that at centromeres and the mating-type locus operates at telomeres during sexual differentiation.

SUBMITTER: Tuzon CT

PROVIDER: S-EPMC2172399 | biostudies-literature | 2004 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

The fission yeast heterochromatin protein Rik1 is required for telomere clustering during meiosis.

Tuzon Creighton T CT Borgstrom Britta B Weilguny Dietmar D Egel Richard R Cooper Julia Promisel JP Nielsen Olaf O

The Journal of cell biology 20040614 6

Telomeres share the ability to silence nearby transcription with heterochromatin, but the requirement of heterochromatin proteins for most telomere functions is unknown. The fission yeast Rik1 protein is required for heterochromatin formation at centromeres and the mating-type locus, as it recruits the Clr4 histone methyltransferase, whose modification of histone H3 triggers binding by Swi6, a conserved protein involved in spreading of heterochromatin. Here, we demonstrate that Rik1 and Clr4, bu ...[more]

PMID: 15197176

Similar Datasets

Fission yeast F-box protein Pof3 is required for genome integrity and telomere function.

Project description:The Skp1-Cullin-1/Cdc53-F-box protein (SCF) ubiquitin ligase plays an important role in various biological processes. In this enzyme complex, a variety of F-box proteins act as receptors that recruit substrates. We have identified a fission yeast gene encoding a novel F-box protein Pof3, which contains, in addition to the F-box, a tetratricopeptide repeat motif in its N terminus and a leucine-rich-repeat motif in the C terminus, two ubiquitous protein-protein interaction domains. Pof3 forms a complex with Skp1 and Pcu1 (fission yeast cullin-1), suggesting that Pof3 functions as an adaptor for specific substrates. In the absence of Pof3, cells exhibit a number of phenotypes reminiscent of genome integrity defects. These include G2 cell cycle delay, hypersensitivity to UV, appearance of lagging chromosomes, and a high rate of chromosome loss. pof3 deletion strains are viable because the DNA damage checkpoint is continuously activated in the mutant, and this leads to G2 cell cycle delay, thereby preventing the mutant from committing lethal mitosis. Pof3 localizes to the nucleus during the cell cycle. Molecular analysis reveals that in this mutant the telomere is substantially shortened and furthermore transcriptional silencing at the telomere is alleviated. The results highlight a role of the SCF(Pof3) ubiquitin ligase in genome integrity via maintaining chromatin structures.

| S-EPMC65083 | biostudies-literature

γH2A is a component of yeast heterochromatin required for telomere elongation.

Project description:Histones of heterochromatin are deacetylated in yeast and methylated in more complex eukaryotes to regulate heterochromatin structure and gene silencing. Here, we report that histone H2A phosphorylated at serine 129 (γH2A) in Saccharomyces cerevisiae is a conceptually new type of heterochromatin modification that functions downstream of silent chromatin assembly. We show that γH2A is enriched throughout yeast telomeric and silent mating locus (HM) heterochromatin where γH2A results from the action of kinases Tel1 and Mec1. Interestingly, mutation of γH2A has no apparent effect on the binding of Sir (silent information regulator) complex or on gene silencing. In contrast, deletion of SIR3 abolishes the formation of γH2A at heterochromatin. To address the function of γH2A, we used a Δrif1 mutant strain in which telomeres are excessively elongated to show that γH2A is required for the optimal recruitment of Cdc13, a regulator of telomere elongation, and for telomere elongation itself. Thus, a histone modification that parallels Sir3 protein binding is shown here to be dispensable for the formation of a silent structure but is important for a crucial heterochromatin-specific downstream function in telomere homeostasis.

| S-EPMC3033431 | biostudies-literature

Regulation of wee1(+) expression during meiosis in fission yeast.

Project description:In eukaryotes, the cyclin-dependent kinase Cdk1p (Cdc2p) plays a central role in entry into and progression through nuclear division during mitosis and meiosis. Cdk1p is activated during meiotic nuclear divisions by dephosphorylation of its tyrosine-15 residue. The phosphorylation status of this residue is largely determined by the Wee1p kinase and the Cdc25p phosphatase. In fission yeast, the forkhead-type transcription factor Mei4p is essential for entry into the first meiotic nuclear division. We recently identified cdc25(+) as an essential target of Mei4p in the control of entry into meiosis I. Here, we show that wee1(+) is another important target of Mei4p in the control of entry into meiosis I. Mei4p bound to the upstream region of wee1(+) in vivo and in vitro and inhibited expression of wee1(+), whereas Mei4p positively regulated expression of the adjacent pseudogene. Overexpression of Mei4p inhibited expression of wee1(+) and induced that of the pseudogene. Conversely, deletion of Mei4p did not decrease expression of wee1(+) but inhibited that of the pseudogene. In addition, deletion of Mei4p-binding regions delayed repression of wee1(+) expression as well as induction of expression of the pseudogene. These results suggest that repression of wee1(+) expression is primarily owing to Mei4p-mediated transcriptional interference.

| S-EPMC4612672 | biostudies-literature

Spindle pole body components are reorganized during fission yeast meiosis.

Project description:During meiosis, the centrosome/spindle pole body (SPB) must be regulated in a manner distinct from that of mitosis to achieve a specialized cell division that will produce gametes. In this paper, we demonstrate that several SPB components are localized to SPBs in a meiosis-specific manner in the fission yeast Schizosaccharomyces pombe. SPB components, such as Cut12, Pcp1, and Spo15, which stay on the SPB during the mitotic cell cycle, disassociate from the SPB during meiotic prophase and then return to the SPB immediately before the onset of meiosis I. Interestingly, the polo kinase Plo1, which normally localizes to the SPB during mitosis, is excluded from them in meiotic prophase, when meiosis-specific, horse-tail nuclear movement occurs. We found that exclusion of Plo1 during this period was essential to properly remodel SPBs, because artificial targeting of Plo1 to SPBs resulted in an overduplication of SPBs. We also found that the centrin Cdc31 was required for meiotic SPB remodeling. Thus Plo1 and a centrin play central roles in the meiotic SPB remodeling, which is essential for generating the proper number of meiotic SPBs and, thereby provide unique characteristics to meiotic divisions.

| S-EPMC3350546 | biostudies-literature

Sir2 is required for Clr4 to initiate centromeric heterochromatin assembly in fission yeast.

Project description:Heterochromatin assembly in fission yeast depends on the Clr4 histone methyltransferase, which targets H3K9. We show that the histone deacetylase Sir2 is required for Clr4 activity at telomeres, but acts redundantly with Clr3 histone deacetylase to maintain centromeric heterochromatin. However, Sir2 is critical for Clr4 function during de novo centromeric heterochromatin assembly. We identified new targets of Sir2 and tested if their deacetylation is necessary for Clr4-mediated heterochromatin establishment. Sir2 preferentially deacetylates H4K16Ac and H3K4Ac, but mutation of these residues to mimic acetylation did not prevent Clr4-mediated heterochromatin establishment. Sir2 also deacetylates H3K9Ac and H3K14Ac. Strains bearing H3K9 or H3K14 mutations exhibit heterochromatin defects. H3K9 mutation blocks Clr4 function, but why H3K14 mutation impacts heterochromatin was not known. Here, we demonstrate that recruitment of Clr4 to centromeres is blocked by mutation of H3K14. We suggest that Sir2 deacetylates H3K14 to target Clr4 to centromeres. Further, we demonstrate that Sir2 is critical for de novo accumulation of H3K9me2 in RNAi-deficient cells. These analyses place Sir2 and H3K14 deacetylation upstream of Clr4 recruitment during heterochromatin assembly.

| S-EPMC3770337 | biostudies-literature

The tail-module of yeast Mediator complex is required for telomere heterochromatin maintenance.

Project description:Eukaryotic chromosome ends have a DNA-protein complex structure termed telomere. Integrity of telomeres is essential for cell proliferation. Genome-wide screenings for telomere length maintenance genes identified several components of the transcriptional regulator, the Mediator complex. Our work provides evidence that Mediator is involved in telomere length regulation and telomere heterochromatin maintenance. Tail module of Mediator is required for telomere silencing by promoting or stabilizing Sir protein binding and spreading on telomeres. Mediator binds on telomere and may be a component of telomeric chromatin. Our study reveals a specific role of Mediator complex at the heterochromatic telomere and this function is specific to telomeres as it has no effect on the HMR locus.

| S-EPMC3258146 | biostudies-literature

The fission yeast FANCM ortholog directs non-crossover recombination during meiosis.

Project description:The formation of healthy gametes depends on programmed DNA double-strand breaks (DSBs), which are each repaired as a crossover (CO) or non-crossover (NCO) from a homologous template. Although most of these DSBs are repaired without giving COs, little is known about the genetic requirements of NCO-specific recombination. We show that Fml1, the Fanconi anemia complementation group M (FANCM)-ortholog of Schizosaccharomyces pombe, directs the formation of NCOs during meiosis in competition with the Mus81-dependent pro-CO pathway. We also define the Rad51/Dmc1-mediator Swi5-Sfr1 as a major determinant in biasing the recombination process in favor of Mus81, to ensure the appropriate amount of COs to guide meiotic chromosome segregation. The conservation of these proteins from yeast to humans suggests that this interplay may be a general feature of meiotic recombination.

| S-EPMC3399777 | biostudies-literature

A chromodomain protein, Chp1, is required for the establishment of heterochromatin in fission yeast.

Project description:The chromodomain is a conserved motif that functions in the epigenetic control of gene expression. Here, we report the functional characterization of a chromodomain protein, Chp1, in the heterochromatin assembly in fission yeast. We show that Chp1 is a structural component of three heterochromatic regions-centromeres, the mating-type region, and telomeres-and that its localization in these regions is dependent on the histone methyltransferase Clr4. Although deletion of the chp1(+) gene causes centromere-specific decreases in Swi6 localization and histone H3-K9 methylation, we show that the role of Chp1 is not exclusive to the centromeres. We found that some methylation persists in native centromeric regions in the absence of Chp1, which is also true for the mating-type region and telomeres, and determined that Swi6 and Chp2 are critical to maintaining this residual methylation. We also show that Chp1 participates in the establishment of repressive chromatin in all three chromosomal regions. These results suggest that different heterochromatic regions share common structural properties, and that centromeric heterochromatin requires Chp1-mediated establishment steps differently than do other heterochromatic regions.

| S-EPMC522800 | biostudies-other

Mkt1 is required for RNAi-mediated silencing and establishment of heterochromatin in fission yeast.

Project description:Constitutive domains of repressive heterochromatin are maintained within the fission yeast genome through self-reinforcing mechanisms involving histone methylation and small RNAs. Non-coding RNAs generated from heterochromatic regions are processed into small RNAs by the RNA interference pathway, and are subject to silencing through both transcriptional and post-transcriptional mechanisms. While the pathways involved in maintenance of the repressive heterochromatin state are reasonably well understood, less is known about the requirements for its establishment. Here, we describe a novel role for the post-transcriptional regulatory factor Mkt1 in establishment of heterochromatin at pericentromeres in fission yeast. Loss of Mkt1 does not affect maintenance of existing heterochromatin, but does affect its recovery following depletion, as well as de novo establishment of heterochromatin on a mini-chromosome. Pathway dissection revealed that Mkt1 is required for RNAi-mediated post-transcriptional silencing, downstream of small RNA production. Mkt1 physically associates with pericentromeric transcripts, and is additionally required for maintenance of silencing and heterochromatin at centromeres when transcriptional silencing is impaired. Our findings provide new insight into the mechanism of RNAi-mediated post-transcriptional silencing in fission yeast, and unveil an important role for post-transcriptional silencing in establishment of heterochromatin that is dispensable when full transcriptional silencing is imposed.

| S-EPMC7026591 | biostudies-literature

Fission yeast Taz1 and RPA are synergistically required to prevent rapid telomere loss.

Project description:The telomere complex must allow nucleases and helicases to process chromosome ends to make them substrates for telomerase, while preventing these same activities from disrupting chromosome end-protection. Replication protein A (RPA) binds to single-stranded DNA and is required for DNA replication, recombination, repair, and telomere maintenance. In fission yeast, the telomere binding protein Taz1 protects telomeres and negatively regulates telomerase. Here, we show that taz1-d rad11-D223Y double mutants lose their telomeric DNA, indicating that RPA (Rad11) and Taz1 are synergistically required to prevent telomere loss. Telomere loss in the taz1-d rad11-D223Y double mutants was suppressed by additional mutation of the helicase domain in a RecQ helicase (Rqh1), or by overexpression of Pot1, a single-strand telomere binding protein that is essential for protection of chromosome ends. From our results, we propose that in the absence of Taz1 and functional RPA, Pot1 cannot function properly and the helicase activity of Rqh1 promotes telomere loss. Our results suggest that controlling the activity of Rqh1 at telomeres is critical for the prevention of genomic instability.

| S-EPMC1877100 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data