The Effect of CDK1 Mediated GOLGI Vesiculation on Mitotic Progression in Mammalian Cells

Abstract

The mammalian Golgi consists of hundreds of Golgi stacks interlinked to form a single ribbon structure in the perinuclear area. During mitosis, the Golgi undergoes two sequential fragmentation steps to break from ribbon to individual stacks, then from stacks to vesicles and tubules. The first fragmentation step is mediated by phosphorylation of the Golgi matrix protein GRASP65 and it has been shown to be essential for G2-M transition. To understand if the second, vesiculating step might be involved in mitotic progression, we looked at GM130, a Golgi matrix protein mitotically phosphorylated by Cdk1 and thought to be essential for the mitotic Golgi vesiculation. When NRK cells were treated with the Cdk1 inhibitor purvalanol A, Golgi vesiculation was blocked and organisation of the mitotic spindle was affected and mitotic progression was delayed. Over expression of a GFP fusion to a GM130 phosphorylation mutant (S25A) had no apparent effect on Golgi vesiculation and mitotic progressio