High impact information on RIF1

• Deletion of the telomeric proteins Rif1 or Rif2 gives rise to longer telomeres by increasing the frequency of elongation events [1].
• Yeast Rif1 associates with telomeres and regulates their length [2].
• In addition, overexpression of either RIF1 or RIF2 decreases telomere length, and co-overexpression of these proteins can reverse the telomere elongation effect of overexpression of the Rap1p carboxyl terminus [3].
• These results suggest that telomere length regulation is mediated by a protein complex consisting of Rif1p and Rif2p, each of which has distinct regulatory functions [3].
• Furthermore, hybrid proteins containing rap1s missense mutations are defective in an interaction with RIF1 in the two-hybrid system [4].

Biological context of RIF1

• However, deletion of both RIF1 and RIF2 in the same cell results in a dramatic increase in telomere length, similar to that seen with a carboxy-terminal truncation of Rap1p [3].
• Strains carrying gene disruptions of RIF1 grow normally but are defective in transcriptional silencing and telomere length regulation, two phenotypes strikingly similar to those of silencing-defective rap1s mutants [4].
• The rif1 mutant also shows some defects in telomere length control and meiosis [5].
• Human Rif1 protein binds aberrant telomeres and aligns along anaphase midzone microtubules [6].
• We showed by microarray analysis that Rif1p association with the chromosome ends extends to subtelomeric regions many kilobases internal to the terminal telomeric repeats and correlates strongly with the previously determined genomic footprints of Rap1p and the Sir2-4 proteins in these regions [7].

Regulatory relationships of RIF1

• SDS4 mutations also suppress the silencing defect caused by mutations in the RAP1-interacting factor RIF1 [8].

Other interactions of RIF1

• Finally, we show that Rif1p and Rif2p can interact with each other in vivo [3].
• The others disrupt the SIR3 and RIF1 genes of C. glabrata [9].
• EPA6 and its close paralogue EPA7 are located in subtelomeric regions and their transcription is regulated by Sir4p and Rif1p, two proteins involved in subtelomeric silencing [10].
• Study of the isolated mutant strains allowed the identification of four genes involved in biofilm formation (RIF1, SIR4, EPA6 and YAK1) [10].
• Lastly, the elg1Delta mutation increases telomere size independently of other previously known telomere maintenance proteins such as the telomerase inhibitor Pif1 or the telomere size regulator Rif1 [11].

References