The role of Cdk1-cyclin B in G1/S transition revealed by chemical genetic inhibition of Cdc7

ABSTRACT: Entry of mammalian cells into DNA synthesis (S-phase) represents a key event in cell division. According to the current cell cycle models, the Cdc7 kinase represents the essential and rate-limiting trigger of DNA replication, acting together with the cyclin-dependent kinase Cdk2. Using chemical genetic systems which allow an acute shutdown of Cdc7 in in vitro cultured cells as well as in vivo in a living mouse, that Cdc7 is dispensable for cell division of many different cell types. Proteomic and phosphoproteomic analysis were performed to elucidate the compensating mechanism. We demonstrate that Cdk1-cyclin B, a kinase currently thought to act exclusively during mitosis, is also active during G1/S transition both in cycling cells and in cells exiting quiescence. We show that Cdc7 and Cdk1-cyclin B play redundant roles during G1/S transition, and at least one of these kinases is needed to allow S-phase entry. These observations revise our fundamental understanding of cell cycle progression by demonstrating that Cdk1-cyclin B physiologically regulates two distinct transitions during cell division cycle, while Cdc7 plays a redundant function in DNA replication. In TMT1, to analyze the expression of Cdc7 and its partners upon auxin-mediated induction of Cdc7 degradation, we performed a TMT analysis of ES cells treated with IAA for 24 hours. In TMT2, to analyze the phosphorylation of Cdc7 targets as a function of time upon degradation of the kinase we performed the time-resolved TMT analysis of ES cells subjected to Cdc7 degradation for three different amounts of time. In TMT3, to determine the ability of Cdk1 to phosphorylate Mcm2, we analyzed the phosphoproteome of mES cells and focused on the phosphorylation of Mcm2 upon Cdk1 inhibition.

INSTRUMENT(S): Orbitrap Eclipse, Orbitrap Fusion Lumos

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Embryo, Embryonic Stem Cell

SUBMITTER: Tian Zhang  

LAB HEAD: Steven Gygi

PROVIDER: PXD025625 | Pride | 2022-03-11

REPOSITORIES: Pride