Abstract
Although mitotic regulation has been extensively studied, several of the mechanisms behind this process have yet to be fully understood. Our group is particularly interested in mechanisms regulating the timing of mitotic exit and how such mechanisms coordinate with other mitotic cues such as spindle orientation. Recent work in our lab has shown that spindle movements in epithelial cells of the developing frog embryo correlate with mitotic exit and perturbations in normal spindle movements lengthen metaphase. Further, these changes in mitotic progression are accompanied by increases in Cdk1 Tyr15 phosphorylation, specifically at cell junctions. We propose that the link between spindle movement and mitotic progression is an important part of the mechanisms influencing spindle orientation in the frog epithelium. Our current work examines the role of Cks2 in the aforementioned mechanism. Cks2 serves as a targeting subunit for the mitotic kinase Cdk1. Specifically, work in yeast suggests Cks2 may direct Cdk1 toward the anaphase‐promoting complex (APC) and interact with both complexes, facilitating the phosphorylation of Cdk1 and activation of the APC and thus help control mitotic exit. In this study, we characterize Cks2's mitotic function in Xenopus laevis. Our aim is to characterize Cks2 distribution throughout mitosis and determine whether perturbing Cks2 function alters mitotic progression in the gastrula‐stage epithelium. We hypothesize that if Cks2 influences Cdk1 function in mitosis, then the two proteins will exhibit similar localization patterns in mitotic cells. We visualized endogenous Cks2 and also expressed GFP‐tagged Cks2 in fixed epithelial tissues of Xenopus laevis embryos through confocal microscopy. Our early data show that Cks2 localization overlaps with that of a phosphorylated Cdk1(pY15) at cell junctions and overexpression of GFP‐tagged Cks2 results in increased levels of Cdk1‐pY15. In addition, the assay expressing a dominant negative version of Cks2 suggests that depletion of endogenous Cks2 activity may contribute to decreased Cdk1‐pY15 at cell junctions and increased cell area. Therefore, these data suggest a link between Cks2 and Cdk1 in mitotic regulation and are a first step toward a greater characterization of Cks2's role in regulating mitotic progression in vertebrate organisms.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Published Version
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