Plk1 inhibition delays mitotic entry revealing early changes to the phosphoproteome in cell division

ABSTRACT: Polo-like kinase 1 (plk1) is a conserved regulator of cell division. During prophase, plk1 phosphorylates direct substrates and is involved in activation of the cyclin-dependent kinase 1 (cdk1). However, the exact functions of plk1 in prophase remain incompletely understood. Here, we inhibited plk1 in synchronous G2 populations of multiple mammalian cell lines. This led to delay or prevention of mitotic entry showing high variability between individual cells. Using a mathematical model, we recapitulate and provide an explanation for this seemingly variable phenotype. We show that plk1-inhibited cells are delayed in a prophase-like state with low cdk1 activity that increases slowly and gradually over hours. These cells display progressively condensing chromosomes, increased microtubule dynamics and reorganization of the actin cortex, while the nuclear envelope remains intact. We then characterize this state by phosphoproteomics, revealing phosphorylation of regulators of chromatin organization and the cytoskeleton consistent with cellular phenotypes. Together, we show that plk1 inhibition stabilizes cells in a prophase-like state with low cdk1 activity displaying a specific set of early mitotic phosphorylations.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Hela Cell

SUBMITTER: Olexandr Dybkov  

LAB HEAD: Henning Urlaub

PROVIDER: PXD060406 | Pride | 2025-03-17

REPOSITORIES: Pride