title: Human Bcl-2 cannot directly inhibit the Caenorhabditis elegans Apaf-1 homologue CED-4, but can interact with EGL-1.
abstract: Although the anti-apoptotic activity of Bcl-2 has been extensively studied, its mode of action is still incompletely understood. In the nematode Caenorhabditis elegans, 131 of 1090 somatic cells undergo programmed cell death during development. Transgenic expression of human Bcl-2 reduced cell death during nematode development, and partially complemented mutation of ced-9, indicating that Bcl-2 can functionally interact with the nematode cell death machinery. Identification of the nematode target(s) of Bcl-2 inhibition would help clarify the mechanism by which Bcl-2 suppresses apoptosis in mammalian cells. Exploiting yeast-based systems and biochemical assays, we analysed the ability of Bcl-2 to interact with and regulate the activity of nematode apoptosis proteins. Unlike CED-9, Bcl-2 could not directly associate with the caspase-activating adaptor protein CED-4, nor could it inhibit CED-4-dependent yeast death. By contrast, Bcl-2 could bind the C. elegans pro-apoptotic BH3-only Bcl-2 family member EGL-1. These data prompt us to hypothesise that Bcl-2 might suppress nematode cell death by preventing EGL-1 from antagonising CED-9, rather than by inhibiting CED-4.
authors.affiliation: Children's Cancer Centre, Royal Children's Hospital, Parkville 3052, Australia.
authors.forename: Anissa M
authors.initials: AM
authors.lastname: Jabbour
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Puryer
authors.forename: Jai Y
authors.initials: JY
authors.lastname: Yu
authors.forename: Trevor
authors.initials: T
authors.lastname: Lithgow
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Riffkin
authors.forename: David M
authors.initials: DM
authors.lastname: Ashley
authors.forename: David L
authors.initials: DL
authors.lastname: Vaux
authors.forename: Paul G
authors.initials: PG
authors.lastname: Ekert
authors.forename: Christine J
authors.initials: CJ
authors.lastname: Hawkins
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D017209:Apoptosis / Q000502:physiology; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D006801:Humans; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000494:pharmacology / Q000502:physiology*; D012097:Repressor Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D051028:bcl-2-Associated X Protein / Q000037:antagonists & inhibitors
chemical_list: D051017:Apoptosis Regulatory Proteins; D029742:Caenorhabditis elegans Proteins; D002135:Calcium-Binding Proteins; C089224:Ced-4 protein, C elegans; C087233:Ced-9 protein, C elegans; C112486:EGL-1 protein, C elegans; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012097:Repressor Proteins; D051028:bcl-2-Associated X Protein