E2F8 is a transcriptional repressor that antagonizes E2F1 at the crossroads of the cell cycle, apoptosis, and cancer. Previously, we discovered that E2F8 is a direct target of the APC/C ubiquitin ligase. Nevertheless, it remains unknown how E2F8 is dynamically controlled throughout the entirety of the cell cycle. Here, using newly developed human cell-free systems that recapitulate distinct inter-mitotic and G1 phases and a continuous transition from prometaphase to G1, we reveal an interlocking dephosphorylation switch coordinating E2F8 degradation with mitotic exit and the activation of APC/CCdh1. Further, we uncover differential proteolysis rates for E2F8 at different points within G1 phase, accounting for its accumulation in late G1 while APC/CCdh1 is still active. Finally, we demonstrate that the F-box protein Cyclin F regulates E2F8 in G2-phase. Altogether, our data define E2F8 regulation throughout the cell cycle, illuminating an extensive coordination between phosphorylation, ubiquitination and transcription in mammalian cell cycle.
Bibliographical noteFunding Information:
We thank Tamar Listovsky-Yulzary, Ofir Hakim, Doron Ginsberg, Itay Koren, Vamsi Mootha, and Yaron Shav-Tal for sharing reagents. The Tzur lab is supported by the Israel Cancer Research Fund, Grant no. RCDA00102, and the Israel Science Foundation Grant nos. 659/16 and 2038/19. The Emanuele lab is supported by the University of North Carolina University Cancer Research Fund, National Institutes of Health (R01GM120309), American Cancer Society (RSG-18-220-01-TBG), and donations from the Brookside Foundation.
© 2020 Wasserman et al.