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PMID:22895252

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Citation

Kawakami, K, Hayashi, A, Nakayama, J and Murakami, Y (2012) A novel RNAi protein, Dsh1, assembles RNAi machinery on chromatin to amplify heterochromatic siRNA. Genes Dev. 26:1811-24

Abstract

In fission yeast, siRNA is generated from pericentromeric noncoding RNA by the RNAi machinery. siRNA synthesis and heterochromatin formation are interdependent, forming a self-reinforcing loop on chromatin. In this system, siRNA is amplified by the RNA-dependent RNA polymerase complex (RDRC) and the endoribonuclease Dcr1, which synthesizes dsRNA and processes the dsRNA, respectively. The amplification is essential for stable heterochromatin formation. Here, a novel gene, dsh1(+) (defect of the gene silencing at centromeric heterochromatin), is identified as an essential component of RNAi-directed heterochromatin assembly. Loss of dsh1(+) abolishes normal RNAi function and heterochromatic gene silencing at pericentromeres. Dsh1 interacts with Dcr1 and RDRC and couples the reactions of both proteins to the effective production of siRNA in vivo. Dsh1 binds to heterochromatin in the absence of RDRC, while RDRC requires Dsh1 for its chromatin-binding activity, suggesting that Dsh1 recruits RDRC to chromatin. Immunofluorescence analysis shows that Dsh1 forms foci at the nuclear periphery, and some Dsh1 foci colocalize with Dcr1 and RDRC. Dsh1 is required for the colocalization of Dcr1 and RDRC. Moreover, loss of the nuclear periphery localization of Dsh1 abolishes Dsh1 function. Taken together, these results suggest that Dsh1 assembles the RNAi machinery on heterochromatin and forms a perinuclear compartment for amplification of heterochromatic siRNA.

Links

PubMed PMC3426760 Online version:10.1101/gad.190272.112

Keywords

Chromatin/metabolism; Endoribonucleases/metabolism; Heterochromatin/metabolism; Mutation; Protein Binding; Protein Structure, Tertiary; Protein Transport; RNA Interference; RNA, Small Interfering/metabolism; Schizosaccharomyces/genetics; Schizosaccharomyces/metabolism; Schizosaccharomyces pombe Proteins/genetics; Schizosaccharomyces pombe Proteins/metabolism

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

SCHPO:RDP1

is_active_in

GO:0005634: nucleus

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

SCHPO:RDP1

is_active_in

GO:0005737: cytoplasm

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

SCHPO:RDP1

involved_in

GO:0031048: heterochromatin assembly by small RNA

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

SCHPO:AGO1

involved_in

GO:0031048: heterochromatin assembly by small RNA

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

SCHPO:DCR1

is_active_in

GO:0005634: nucleus

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

SCHPO:DCR1

involved_in

GO:0031048: heterochromatin assembly by small RNA

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

SCHPO:YBM4

is_active_in

GO:0005634: nucleus

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

SCHPO:YBM4

involved_in

GO:0031048: heterochromatin assembly by small RNA

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

SCHPO:YBM4

is_active_in

GO:0005721: pericentric heterochromatin

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

SCHPO:DCR1

involved_in

GO:0070868: heterochromatin organization involved in chromatin silencing

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

SCHPO:DCR1

part_of

GO:0005634: nucleus

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

Notes

See also

References

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