Fig. 4.

Accumulation of telomere-associated TERRA induces premature senescence and telomere recombination. (A) Overexpressing RNase H1 reduces the level of telomere-associated TERRA in tlc1 tho2 cells. Freshly dissected tlc1 and tlc1 tho2 cells harboring the plasmid pGAL1–RNH1 were used in ChIP analyses with antibodies against Rap1. PCR analyses were used to determine the levels of Rap1-associated TERRA. (B) Overexpressing RNase H1 rescues premature senescence in tlc1 tho2 and tlc1 hpr1 cells. Freshly dissected colonies with the indicated mutations were continuously streaked onto YC plates. (C) RNH1 overexpression delays type II telomere recombination in tlc1 cells. DNA from the indicated strains was then analyzed by Southern blotting using a C_1–3A probe. (D) Overexpressing C_1–3A transcripts delays survivor formation in tlc1 cells. Freshly dissected tlc1 cells carrying plasmid pRS426-Gal (vector), pRS426-Gal-TG_1–3 (TG_1–3), or pRS426-Gal-C_1–3A (C_1–3A) were continuously streaked at 30 °C. These plates were photographed after incubation at 30 °C for 3–4 d. (E) Excess amounts of C_1–3A transcript delays type II recombination in tlc1 cells. DNA from the indicated strains was then analyzed by Southern blotting using a C_1–3A probe.