Components of the spindle assembly checkpoint regulate the anaphase-promoting complex during meiosis in Caenorhabditis elegans.
Temperature-sensitive mutations in subunits of the Caenorhabditis elegans anaphase-promoting complex (APC) arrest at metaphase of meiosis I at the restrictive temperature. Embryos depleted of the APC co-activator FZY-1 by RNAi also arrest at this stage. To identify regulators and potential substrates of the APC, we performed a genetic suppressor screen with a weak allele of the APC subunit MAT-3/CDC23/APC8, whose defects are specific to meiosis. Twenty-seven suppressors that resulted in embryonic viability and larval development at the restrictive temperature were isolated. We have identified the molecular lesions in 18 of these suppressors, which correspond to five genes. In addition to a single intragenic suppressor, we found mutations in the APC co-activator fzy-1 and in three spindle assembly checkpoint genes, mdf-1, mdf-2, and mdf-3/san-1, orthologs of Mad1, Mad2, and Mad3, respectively. Reduction-of-function alleles of mdf-2 and mdf-3 suppress APC mutants and exhibit pleiotropic phenotypes in an otherwise wild-type background. Analysis of a single separation-of-function allele of mdf-1 suggests that MDF-1 has a dual role during development. These studies provide evidence that components of the spindle assembly checkpoint may regulate the metaphase-to-anaphase transition in the absence of spindle damage during C. elegans meiosis.
Stein
Kathryn K
KK
Laboratory of Biochemistry and Genetics, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA.
Davis
Edward S
ES
Hays
Thomas
T
Golden
Andy
A
D000705:Anaphase / Q000502:physiology; D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002453:Cell Cycle; D018816:Genes, cdc / Q000502:physiology*; D008540:Meiosis / Q000502:physiology*; D008677:Metaphase / Q000502:physiology; D009154:Mutation; D010641:Phenotype; D021122:Protein Subunits; D034741:RNA, Small Interfering / Q000494:pharmacology; D008941:Spindle Apparatus; D013489:Suppression, Genetic; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics*
D029742:Caenorhabditis elegans Proteins; D021122:Protein Subunits; D034741:RNA, Small Interfering; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome