A new Riff: Rif1 eats its cake and has it too

Area of Science:

• Molecular biology
• DNA repair mechanisms
• Eukaryotic cell biology

Background:

• Rif1 protein is conserved across eukaryotes and plays a role in telomere homeostasis in yeast.
• Human Rif1 functions at DNA double-strand breaks (DSBs) with 53BP1, inhibiting resection and promoting nonhomologous end-joining (NHEJ).

Purpose of the Study:

• To investigate the role of yeast Rif1 at DSBs.
• To compare the function of yeast Rif1 with its human counterpart at DSBs.

Main Methods:

• Recruitment of Rif1 to DSBs in yeast.
• Analysis of Rif1's effect on DNA resection and NHEJ.
• Investigating the interaction between Rif1 and Rad9 (53BP1 ortholog).

Main Results:

• Yeast Rif1 is recruited to DSBs.
• In contrast to human Rif1, yeast Rif1 promotes DNA resection.
• Rif1 stimulates resection by limiting the access of Rad9 to DSBs.

Conclusions:

• Yeast Rif1 plays a pro-resection role at DSBs, contrasting with the anti-resection function of human Rif1.
• Rif1's function at DSBs is divergent between yeast and human, suggesting distinct roles in DNA damage response.
• Rif1 may regulate DNA repair pathway choice by modulating access of key proteins like Rad9 to DSBs.