Proteins involved in cell division play additional roles in early development

Abstract

Several proteins that are known to play a crucial role in mitosis may have alternative functions in embryogenesis. To test this hypothesis, we examined the spatial and temporal expression of the transcripts that encode proteins involved in mitosis throughout development, including those that encode for motor proteins, cytoskeletal elements and their modulators, vesicular transport, and cell cycle regulators. Results indicate that these transcripts have different expression patterns in various cell types. Interestingly, Cyclin Dependent Kinase 1 (CDK1), Polo Like Kinase 1 (PLK1), Ran, Rab11, CENP-E, Aurora A (AurkA), Staufen, Dynein, and Kinesin-13 transcripts are expressed by endomesodermal cells of the blastula, the multipotent stem cells in coelomic pouches, and/or the skeletogenic mesoderm of the gastrula that are not actively dividing. To further test that proteins important for mitosis may perform additional functions during embryogenesis, we treated embryos with CDK1, PLK1, and AurkA inhibitors, which result in a dose-dependent developmental arrest or delay, gastrulation defects, and shortened skeletal spicules. Further analysis indicates that the number of mesodermally-derived pigment cells is significantly less in CDK1 and PLK1 inhibited embryos and significantly increased in Aurora kinase inhibited embryos. Overall, these results indicate that proteins involved in mitosis likely perform additional functions during embryogenesis.