Rap1-dependent pathways coordinate cytokinesis in Dictyostelium.
Bottom Line: Hyperactivation of Rap1 results in severe growth delays and defective spindle formation in adherent cells and cell death in suspension.Furthermore, Rap mutants show aberrant regulation of the actomyosin cytoskeleton, resulting in extended furrow ingression times and asymmetrical cell division.Importantly, mutated forms of Rap also affect cytokinesis in other organisms, suggesting a conserved role for Rap in cell division.
Affiliation: Department of Cell Biochemistry, University of Groningen, 9747 AG Groningen, Netherlands.Show MeSH
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Mentions: Staining of Rap1G12V cells grown on substrates in the presence or absence of DOX for 48 h with 4′,6-diamidino-2-phenylindole (DAPI) fluorescent dye showed no significantly (p > 0.01) different average number of nuclei in Rap1G12V-expressing cells (1.34, n = 114, SEM = 0.08) compared with the uninduced control cells (1.16, n = 90, SEM = 0.06). Although hyperactivation of Rap does not influence the number of nuclei, it dramatically affects nuclear size and shape. In control cells, the nuclei appeared small, round, and evenly sized both in single and in multinucleated cells (nuclear size of 8.6 ± 2 μm2; Figure 3A). In contrast, Rap1G12V cells had irregularly shaped and much larger nuclei (25.1 ± 13.6 μm2). The small fraction of multinucleated Rap1G12V cells had nuclei of various shapes and sizes, and some of them were elongated or appeared to be connected (Figure 3A).
Affiliation: Department of Cell Biochemistry, University of Groningen, 9747 AG Groningen, Netherlands.