ZYG-9, TAC-1 and ZYG-8 together ensure correct microtubule function throughout the cell cycle of C. elegans embryos.
The early Caenorhabditis elegans embryo is well suited for investigating microtubule-dependent cell division processes. In the one-cell stage, the XMAP215 homologue ZYG-9, associated with the TACC protein TAC-1, promotes microtubule growth during interphase and mitosis, whereas the doublecortin domain protein ZYG-8 is required for anaphase spindle positioning. How ZYG-9, TAC-1 and ZYG-8 together ensure correct microtubule-dependent processes throughout the cell cycle is not fully understood. Here, we identify new temperature-sensitive alleles of zyg-9 and tac-1. Analysis of ZYG-9 and TAC-1 distribution in these mutants identifies amino acids important for centrosomal targeting and for stability of the two proteins. This analysis also reveals that TAC-1 is needed for correct ZYG-9 centrosomal enrichment. Moreover, we find that ZYG-9, but not TAC-1, is limiting for microtubule-dependent processes in one-cell-stage embryos. Using two of these alleles to rapidly inactivate ZYG-9-TAC-1 function, we establish that this complex is required for correct anaphase spindle positioning. Furthermore, we uncover that ZYG-9-TAC-1 and ZYG-8 function together during meiosis, interphase and mitosis. We also find that TAC-1 physically interacts with ZYG-8 through its doublecortin domain, and that in vivo TAC-1 and ZYG-8 are part of a complex that does not contain ZYG-9. Taken together, these findings indicate that ZYG-9-TAC-1 and ZYG-8 act in a partially redundant manner to ensure correct microtubule assembly throughout the cell cycle of early C. elegans embryos.
Bellanger
Jean-Michel
JM
Swiss Institute for Experimental Cancer Research (ISREC), Swiss Federal Institute of Technology (EPFL), School of Life Sciences, Lausanne, Switzerland.
Carter
J Clayton
JC
Phillips
Jennifer B
JB
Canard
Coralie
C
Bowerman
Bruce
B
Gönczy
Pierre
P
D000483:Alleles; D000705:Anaphase; D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology* / Q000196:embryology / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000378:metabolism*; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism*; D020964:Embryo Loss; D004625:Embryo, Nonmammalian / Q000166:cytology* / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D008941:Spindle Apparatus / Q000378:metabolism
D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins; C524441:TAC-1 protein, C elegans; C112750:ZYG-9 protein, C elegans; C439929:zyg-8 protein, C elegans