Cdc14 phosphatase promotes segregation of telomeres through repression of RNA polymerase II transcription

Kinases and phosphatases regulate mRNA synthesis through post-translational modification of the C-terminal domain (CTD) of the largest subunit of RNA polymerase II (1). In yeast, the phosphatase Cdc14 is required for mitotic exit (2,3) and for segregation of repetitive regions (4). Cdc14 is also a subunit of the silencing complex RENT (5,6), but no roles in transcription repression have been described. Here we report that inactivation of Cdc14 causes silencing defects at the intergenic spacer sequences (IGS) of ribosomal genes during interphase and at Y’ repeats in sub-telomeric regions during mitosis. We show that Cdc14 role in silencing is independent from the RENT deacetylase subunit Sir2. Instead, Cdc14 acts directly on RNA Polymerase II by targeting CTD phosphorylation at S(2) and S(5). We also find that Cdc14 role as a CTD phosphatase is conserved in humans. Finally, telomere segregation defects in cdc14 mutants (4) correlate with the presence of sub-telomeric Y’ elements and can be rescued by transcriptional inhibition of RNA Pol II.