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New Positive Regulators of lin-12 Activity in Caenorhabditis elegans Include the BRE-5/Brainiac Glycosphingolipid Biosynthesis Enzyme

2005; Oxford University Press; Volume: 171; Issue: 4 Linguagem: Inglês

10.1534/genetics.105.048041

1943-2631

Iskra Katic, Ludovic Vallier, Iva Greenwald,

Plant Stress Responses and Tolerance

Abstract Screens for suppressors of lin-12 hypermorphic alleles in C. elegans have identified core components and modulators of the LIN-12/Notch signaling pathway. Here we describe the recovery of alleles of six new genes from a screen for suppressors of the egg-laying defect associated with elevated lin-12 activity. The molecular identification of one of the new suppressor genes revealed it as bre-5, which had previously been identified in screens for mutations that confer resistance to Bt toxin in C. elegans. bre-5 is the homolog of D. melanogaster brainiac. BRE-5/Brainiac catalyzes a step in the synthesis of glycosphingolipids, components of lipid rafts that are thought to act as platforms for association among certain kinds of membrane-bound proteins. Reducing the activity of several other genes involved in glycosphingolipid biosynthesis also suppresses the effects of constitutive lin-12 activity. Genetic analysis and cell ablation experiments suggest that bre-5 functions prior to ligand-induced ectodomain shedding that activates LIN-12 for signal transduction.