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Resources » Paper

AF Severson et al. (1999) International C. elegans Meeting "Cytokinesis in C. elegans embryos: analysis of cyk-1 function"

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    Publication type:
    Meeting_abstract
    WormBase ID:
    WBPaper00023628

    AF Severson, JC Carter, DR Hamill, DL Baillie, & BA Bowerman (1999). Cytokinesis in C. elegans embryos: analysis of cyk-1 function presented in International C. elegans Meeting. Unpublished information; cite only with author permission.

    cyk-1 encodes an FH protein required for cytokinesis in C. elegans embryos. Embryos homozygous for weak alleles of cyk-1 form cleavage furrows which frequently ingress extensively through the cytoplasm before failing. CYK-1 protein localizes cortically in cleavage furrows, but is detectable only after substantial ingression. We have proposed a model in which CYK-1 functions late in cytokinesis to stabilize cleavage furrows through interactions with the contractile ring and mitotic spindle, and that CYK-1 requires these interactions for its localization. We have tested this model in three ways: analysis of a stronger cyk-1 allele, double mutant analysis, and immunolocalization experiments. Worms homozygous for cyk-1(s2833) , our strongest allele, are sterile, so the cytokinesis defect observed in weak alleles may not be the null phenotype. Embryos from cyk-1(s2833)/cyk-1(t1568) mutant worms fail to furrow. Thus, cyk-1 may also be required for an early step in cytokinesis. Further evidence that cyk-1 functions early in cytokinesis comes from analysis of cyk-1; zen-4 double mutant embryos. ZEN-4 is a mitotic kinesin-like protein that localizes to the spindle interzone. zen-4(or153ts) mutant embryos produce extensive furrows that ultimately regress, similar to the weak cyk-1(or36) phenotype. In contrast to either single mutant, cyk-1(or36); zen-4(or153ts) double mutant embryos fail to form cleavage furrows. We conclude that cyk-1 interacts with the ZEN-4 kinesin-like protein, and these genes function early in cytokinesis. To further test our model, we examined CYK-1 localization in zen-4 mutant embryos. CYK-1 accumulates normally in zen-4 mutant embryos; thus, function of this spindle-associated protein is not required for CYK-1 localization. Additionally, inactivation of mlc-4 , a non-muscle myosin II regulatory light chain required for cleavage furrow ingression, does not prevent cortical CYK-1 localization. Thus, proximity between the cleavage furrow and the spindle are not required for CYK-1 localization. We are currently performing experiments to identify requirements for CYK-1 localization and to understand the genetic interaction between cyk-1 and zen-4 .


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