PMID:16407326

Citation	Hansen, KR, Ibarra, PT and Thon, G (2006) Evolutionary-conserved telomere-linked helicase genes of fission yeast are repressed by silencing factors, RNAi components and the telomere-binding protein Taz1. Nucleic Acids Res. 34:78-88
Abstract	In Schizosaccharomyces pombe the RNAi machinery and proteins mediating heterochromatin formation regulate the transcription of non-coding centromeric repeats. These repeats share a high sequence similarity with telomere-linked helicase (tlh) genes, implying an ancestral relationship between the two types of elements and suggesting that transcription of the tlh genes might be regulated by the same factors as centromeric repeats. Indeed, we found that mutants lacking the histone methyltransferase Clr4, the Pcu4 cullin, Clr7 or Clr8, accumulate high levels of tlh forward and reverse transcripts. Mutations and conditions perturbing histone acetylation had similar effects further demonstrating that the tlh genes are normally repressed by heterochromatin. In contrast, mutations in the RNAi factors Dcr1, Ago1 or Rdp1 led only to a modest derepression of the tlh genes indicating an alternate pathway recruits heterochromatin components to telomeres. The telomere-binding protein Taz1 might be part of such a redundant pathway, tlh transcripts being present at low levels in Deltataz1 mutants and at higher levels in Deltataz1 Deltadcr1 double mutants. Surprisingly, the chromodomain protein Chp1, a component of the Ago1-containing RITS complex, contributes more to tlh repression than Ago1, indicating the repressive effects of Chp1 are partially independent of RITS. The tlh genes are found in the subtelomeric regions of several other fungi raising the intriguing possibility of conserved regulation and function.
Links	PubMed PMC1326240 Online version:10.1093/nar/gkj415
Keywords	Adenosine Triphosphatases/genetics; Base Sequence; Centromere/chemistry; Conserved Sequence; DNA Helicases/genetics; Enzyme Inhibitors/pharmacology; Evolution, Molecular; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Fungal; Gene Silencing; Heterochromatin/genetics; Histone Deacetylase Inhibitors; Hydroxamic Acids/pharmacology; RNA Interference; RecQ Helicases; Repetitive Sequences, Nucleic Acid; Schizosaccharomyces/enzymology; Schizosaccharomyces/genetics; Schizosaccharomyces/metabolism; Schizosaccharomyces pombe Proteins/metabolism; Sequence Homology, Nucleic Acid; Telomere; Telomere-Binding Proteins/metabolism; Transcription Factors/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
SCHPO:TAZ1	involved_in	GO:0000122: negative regulation of transcription by RNA polymerase II	ECO:0000315: mutant phenotype evidence used in manual assertion		P	has_regulation_target:(PomBase:SPAC212.11)	Seeded From UniProt	complete
SCHPO:TAZ1	involved_in	GO:0000122: negative regulation of transcription by RNA polymerase II	ECO:0000315: mutant phenotype evidence used in manual assertion		P	has_regulation_target:(PomBase:SPBCPT2R1.08c)	Seeded From UniProt	complete
SCHPO:CLR4	involved_in	GO:0000122: negative regulation of transcription by RNA polymerase II	ECO:0000315: mutant phenotype evidence used in manual assertion		P	has_regulation_target:(PomBase:SPAC212.11)	Seeded From UniProt	complete
SCHPO:CLR4	involved_in	GO:0000122: negative regulation of transcription by RNA polymerase II	ECO:0000315: mutant phenotype evidence used in manual assertion		P	has_regulation_target:(PomBase:SPBCPT2R1.08c)	Seeded From UniProt	complete
SCHPO:CLR3	involved_in	GO:0000122: negative regulation of transcription by RNA polymerase II	ECO:0000316: genetic interaction evidence used in manual assertion	PomBase:SPBC36.05c	P	has_regulation_target:(PomBase:SPAC212.11)	Seeded From UniProt	complete
SCHPO:CLR3	involved_in	GO:0000122: negative regulation of transcription by RNA polymerase II	ECO:0000316: genetic interaction evidence used in manual assertion	PomBase:SPBC36.05c	P	has_regulation_target:(PomBase:SPBCPT2R1.08c)	Seeded From UniProt	complete

References

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