SIR-dependent repression of non-telomeric genes in Saccharomyces cerevisiae?

The proteins Sir2, Sir3 and Sir4 repress transcription of the silent mating-type loci HML and HMR and of reporter genes inserted at telomeres. Previous microarray analyses suggested that additional non-telomeric genes exist which are repressed by the Sir proteins. In this study, we tested the expression of 12 such genes by Northern analysis and RT-PCR. However, we were unable to verify their SIR-dependent regulation, which suggests that SIR-mediated repression may be restricted to the known repressed regions.