C. elegans MAC-1, an essential member of the AAA family of ATPases, can bind CED-4 and prevent cell death.
In the nematode Caenorhabditis elegans, CED-4 plays a central role in the regulation of programmed cell death. To identify proteins with essential or pleiotropic activities that might also regulate cell death, we used the yeast two-hybrid system to screen for CED-4-binding proteins. We identified MAC-1, a member of the AAA family of ATPases that is similar to Smallminded of Drosophila. Immunoprecipitation studies confirm that MAC-1 interacts with CED-4, and also with Apaf-1, the mammalian homologue of CED-4. Furthermore, MAC-1 can form a multi-protein complex that also includes CED-3 or CED-9. A MAC-1 transgene under the control of a heat shock promoter prevents some natural cell deaths in C. elegans, and this protection is enhanced in a ced-9(n1950sd)/+ genetic background. We observe a similar effect in mammalian cells, where expression of MAC-1 can prevent CED-4 and CED-3 from inducing apoptosis. Finally, mac-1 is an essential gene, since inactivation by RNA-mediated interference causes worms to arrest early in larval development. This arrest is similar to that observed in Smallminded mutants, but is not related to the ability of MAC-1 to bind CED-4, since it still occurs in ced-3 or ced-4 null mutants. These results suggest that MAC-1 identifies a new class of proteins that are essential for development, and which might regulate cell death in specific circumstances.
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Department of Pathology and Comprehensive Cancer Center, University of Michigan Medical School, The University of Michigan, Ann Arbor, Michigan 48109, USA.
Chen
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PJ
Chen
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Hu
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Nuñez
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Ellis
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D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D017209:Apoptosis / Q000502:physiology*; D053477:Apoptotic Protease-Activating Factor 1; D017173:Caenorhabditis elegans / Q000166:cytology / Q000235:genetics* / Q000254:growth & development*; D029742:Caenorhabditis elegans Proteins; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics; D002460:Cell Line; D003001:Cloning, Molecular; D004330:Drosophila; D029721:Drosophila Proteins; D018507:Gene Expression Regulation, Developmental; D015801:Helminth Proteins / Q000378:metabolism*; D006801:Humans; D019476:Insect Proteins / Q000235:genetics; D007814:Larva; D008969:Molecular Sequence Data; D011506:Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae / Q000254:growth & development; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014162:Transfection
C506592:APAF1 protein, human; D053477:Apoptotic Protease-Activating Factor 1; D029742:Caenorhabditis elegans Proteins; D002135:Calcium-Binding Proteins; C089224:Ced-4 protein, C elegans; D018797:Cell Cycle Proteins; D029721:Drosophila Proteins; D015801:Helminth Proteins; D019476:Insect Proteins; D011506:Proteins; C111665:smid protein, Drosophila; D000251:Adenosine Triphosphatases