title: Regulation of subtelomeric silencing during stress response.
abstract: Sir proteins play a critical role in silent chromatin domains. While mutations can cause derepression of heterochromatin, it remains unclear whether silencing is actively involved in transcriptional control under changing environmental conditions. We find that TOR inhibits Sir3 phosphorylation. Rapamycin or stress induced by chlorpromazine leads to activation of MAP kinase Mpk1/Slt2, which phosphorylates Sir3. Sir3 hyperphosphorylation is correlated with reduced subtelomeric silencing, increased subtelomeric cell wall gene expression, and stress resistance to chlorpromazine, but does not affect the silent HML and rDNA loci. Based on these observations, we propose that regulation of silencing may be used to control gene expression at specific silent chromatin domains in response to stress and possibly other environmental changes.
authors.affiliation: Department of Pathology and Immunology, Washington University School of Medicine, 63110, St. Louis, MO 63110, USA.
authors.forename: Wandong
authors.initials: W
authors.lastname: Ai
authors.forename: Paula G
authors.initials: PG
authors.lastname: Bertram
authors.forename: Chi Kwan
authors.initials: CK
authors.lastname: Tsang
authors.forename: Ting Fung
authors.initials: TF
authors.lastname: Chan
authors.forename: X F Steven
authors.initials: XF
authors.lastname: Zheng
mesh_terms: D002843:Chromatin / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D020868:Gene Silencing / Q000502:physiology*; D005800:Genes, Fungal; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae / Q000502:physiology*; D020123:Sirolimus / Q000494:pharmacology; D016615:Telomere / Q000235:genetics*
chemical_list: D002843:Chromatin; C084122:SIR3 protein, S cerevisiae; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D020928:Mitogen-Activated Protein Kinases; D020123:Sirolimus