Cyclin F-dependent degradation of E2F7 is critical for DNA repair and G2-phase progression

Area of Science:

• Cell Biology
• Molecular Biology
• Cancer Research

Background:

• Atypical E2F proteins (E2F7 and E2F8) function as tumor suppressors by inhibiting genes essential for cell cycle progression.
• While E2F7 and E2F8 degradation by APC/C^Cdh1 during G1 is known, the G2 phase downregulation mechanism remained unclear.

Purpose of the Study:

• To elucidate the mechanism regulating atypical E2F stability during the G2 phase of the cell cycle.
• To investigate the role of SCF^{cyclin F} in the degradation of E2F7 and E2F8.

Main Methods:

• Investigated the interaction between E2F7 and SCF^{cyclin F} using mutant analysis.
• Assessed the degradation of E2F7 and E2F8 in response to cyclin F.
• Utilized live cell imaging to observe DNA damage response and cell cycle progression.

Main Results:

• E2F7 is specifically targeted for degradation by SCF^{cyclin F} during G2 via interaction with its CY motif.
• SCF^{cyclin F} also induces E2F8 degradation, but through a distinct mechanism not involving the cyclin domain or CY motifs.
• Depletion of cyclin F leads to an atypical E2F-dependent G2/M delay and impaired DNA repair.

Conclusions:

• SCF^{cyclin F} is a key regulator of atypical E2F stability during G2 phase.
• Cyclin F-mediated degradation of E2F7 and E2F8 is essential for efficient DNA repair and timely cell cycle progression.