Environment-responsive transcription factors bind subtelomeric elements and regulate gene silencing.

ABSTRACT

Subtelomeric chromatin is subject to evolutionarily conserved complex epigenetic regulation and is implicated in numerous aspects of cellular function including formation of heterochromatin, regulation of stress response pathways and control of lifespan. Subtelomeric DNA is characterized by the presence of specific repeated segments that serve to propagate silencing or to protect chromosomal regions from spreading epigenetic control. In this study, analysis of genome-wide chromatin immunoprecipitation and expression data, suggests that several yeast transcription factors regulate subtelomeric silencing in response to various environmental stimuli through conditional association with proto-silencing regions called X elements. In this context, Oaf1p, Rox1p, Gzf1p and Phd1p control the propagation of silencing toward centromeres in response to stimuli affecting stress responses and metabolism, whereas others, including Adr1p, Yap5p and Msn4p, appear to influence boundaries of silencing, regulating telomere-proximal genes in Y' elements. The factors implicated here are known to control adjacent genes at intrachromosomal positions, suggesting their dual functionality. This study reveals a path for the coordination of subtelomeric silencing with cellular environment, and with activities of other cellular processes.