Figure 4.

Overexpression of RNase H1 in vivo reduces telomeric R-loops and TERRA. (A) Overexpressed RNase H1 reduces R-loops at telomeres in wt and thp2-Δ strains. Cells were grown in YPD or in YPGal at 25°C to either repress or induce RNase H1. R-loops were immunoprecipitated and analysed as in Figure 3. Values of three independent biological replicates with standard deviation are shown. Statistical analyses are as in Figure 1. (B) TERRA levels are reduced in thp2-Δ cells upon RNase H1 overexpression. Strains were grown as above and TERRA transcribed from telomeres 1L, 7L, 10R, 13R, 15L, 3*Y′, 4*Y′, 6*Y′ and RNA derived from PMA1 3′ were quantified by qRT-PCR. RNA levels relative to wt of three independent biological replicates normalized against actin with standard deviations are shown. Statistical analyses were calculated using the Student’s t-test (*P<0.05, **P<0.03 and ***P<0.01).