Heritable capture of heterochromatin dynamics in Saccharomyces cerevisiae

Elife. 2015 Jan 12:4:e05007. doi: 10.7554/eLife.05007.

Abstract

Heterochromatin exerts a heritable form of eukaryotic gene repression and contributes to chromosome segregation fidelity and genome stability. However, to date there has been no quantitative evaluation of the stability of heterochromatic gene repression. We designed a genetic strategy to capture transient losses of gene silencing in Saccharomyces as permanent, heritable changes in genotype and phenotype. This approach revealed rare transcription within heterochromatin that occurred in approximately 1/1000 cell divisions. In concordance with multiple lines of evidence suggesting these events were rare and transient, single-molecule RNA FISH showed that transcription was limited. The ability to monitor fluctuations in heterochromatic repression uncovered previously unappreciated roles for Sir1, a silencing establishment factor, in the maintenance and/or inheritance of silencing. In addition, we identified the sirtuin Hst3 and its histone target as contributors to the stability of the silenced state. These approaches revealed dynamics of a heterochromatin function that have been heretofore inaccessible.

Keywords: S. cerevisiae; Sir2; Sir3; Sir4; bistability; chromosomes; epigenetics; genes; histone H3.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Diploidy
  • Gene Deletion
  • Gene Silencing
  • Genes, Mating Type, Fungal
  • Green Fluorescent Proteins / metabolism
  • Hemizygote
  • Heterochromatin / metabolism*
  • Histones / metabolism
  • Imaging, Three-Dimensional
  • In Situ Hybridization, Fluorescence
  • Inheritance Patterns / genetics*
  • Integrases / metabolism
  • Luminescent Proteins / metabolism
  • Red Fluorescent Protein
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism
  • Sirtuins / genetics
  • Transcription, Genetic

Substances

  • Heterochromatin
  • Histones
  • Luminescent Proteins
  • Saccharomyces cerevisiae Proteins
  • Green Fluorescent Proteins
  • Cre recombinase
  • Integrases
  • Sirtuins