Taz1-Shelterin promotes facultative heterochromatin assembly at chromosome-internal sites containing late replication origins [BrdU]

ABSTRACT: BrdU profiling of replication activity in hydroxyurea treated synchronous culture of fission yeast. Facultative heterochromatin regulates gene expression, but its assembly is poorly understood. Previously, we identified facultative heterochromatin islands in the fission yeast genome and found that RNA elimination machinery promotes island assembly at meiotic genes. Here, we report that Taz1, a component of the telomere protection complex Shelterin, is required to assemble heterochromatin islands at regions corresponding to late replication origins that are sites of double-strand break formation during meiosis. The loss of Taz1 and other Shelterin subunits, including Ccq1 that interacts with Clr4/Suv39h, abolishes heterochromatin at late origins and causes defective silencing of associated genes. Moreover, the late origin regulator Rif1 affects heterochromatin at Taz1-dependent islands and subtelomeric regions. We uncover a connection between heterochromatin and replication control, and show that heterochromatin factors affect timing of replication. These analyses implicate Shelterin in facultative heterochromatin assembly at late origins, which has important implications for the maintenance of genome stability and gene regulation. Cdc25-22 cells carrying thymidine kinase and human nucleoside transporter expression modules were arrested at the G2/M boundary. After release into the cell cycle in minimal medium supplemented with hydroxyurea and 5’-bromo-2’-deoxyuridine (BrdU) cells were collected at time corresponding to maximal septation index and fixed by treatment with sodium azide. BrdU labeled DNA was recovered by immunoprecipitation, amplified by random-primed PCR and after conjugation with Cy5 (IP) or Cy3 (input DNA) analyzed on Agilent 60mer array.

ORGANISM(S): Schizosaccharomyces pombe

SUBMITTER: Shiv Grewal 

PROVIDER: E-GEOD-78819 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress