title: Suppressors of spindle checkpoint defect (such) mutants identify new mdf-1/MAD1 interactors in Caenorhabditis elegans.
abstract: The spindle assembly checkpoint (SAC) governs the timing of metaphase-to-anaphase transition and is essential for genome stability. The Caenorhabditis elegans mutant strain gk2 carries a deletion within the mdf-1/MAD1 gene that results in death of the homozygous strain after two or three generations. Here we describe 11 suppressors of the mdf-1(gk2) lethality, 10 identified in an ethyl methanesulfonate (EMS) mutagenesis screen and 1 isolated using the dog-1(gk10) (deletions of guanine-rich DNA) mutator strain. Using time-lapse imaging of early embryonic cells and germline mitotic division, we demonstrate that there are two classes of suppressors. Eight suppressors compensate for the loss of the checkpoint by delaying mitotic progression, which coincides with securin (IFY-1/Pds1) accumulation; three suppressors have normal IFY-1/Pds1 levels and normal anaphase onset. Furthermore, in the class of suppressors with delayed mitotic progression, we have identified four alleles of known suppressors emb-30/APC4 and fzy-1/CDC20, which are components of the anaphase-promoting complex/cyclosome (APC/C). In addition, we have identified another APC/C component capable of bypassing the checkpoint requirement that has not previously been described in C. elegans. The such-1/APC5-like mutation, h1960, significantly delays anaphase onset both in germline and in early embryonic cells.
authors.affiliation: Department of Medical Genetics, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
authors.forename: Maja
authors.initials: M
authors.lastname: Tarailo
authors.forename: Risa
authors.initials: R
authors.lastname: Kitagawa
authors.forename: Ann M
authors.initials: AM
authors.lastname: Rose
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000166:cytology / Q000196:embryology / Q000235:genetics* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D005260:Female; D017238:Genes, Helminth; D005804:Genes, Lethal; D007248:Infertility, Male / Q000235:genetics; D008297:Male; D008938:Mitosis / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D017386:Sequence Homology, Amino Acid; D013489:Suppression, Genetic
chemical_list: D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C581873:IFY-1 protein, C elegans; C412839:MDF-1 protein, C elegans