Caenorhabditis elegans ABCRNAi transporters interact genetically with rde-2 and mut-7

Abstract

RNA interference (RNAi) mechanisms are conserved and consist of an interrelated network of activities that not only respond to exogenous dsRNA, but also perform endogenous functions required in the fine tuning of gene expression and in maintaining genome integrity. Not surprisingly, RNAi functions have widespread influences on cellular function and organismal development. Previously, we observed a reduced capacity to mount an RNAi response in nine Caenorhabditis elegans mutants that are defective in ABC transporter genes (ABCRNAi mutants). Here, we report an exhaustive study of mutants, collectively defective in 49 different ABC transporter genes, that allowed for the categorization of one additional transporter into the ABCRNAi gene class. Genetic complementation tests reveal functions for ABC RNAi transporters in the mut-7/rde-2 branch of the RNAi pathway. These second-site noncomplementation interactions suggest that ABC RNAi proteins and MUT-7/RDE-2 function together in parallel pathways and/or as multiprotein complexes. Like mut-7 and rde-2, someABCRNAi mutants display transposon silencing defects. Finally, our analyses reveal a genetic interaction network of ABCRNAi gene function with respect to this part of the RNAi pathway. From our results, we speculate that the coordinated activities of ABCRNAi transporters, through their effects on endogenous RNAi-related mechanisms, ultimately affect chromosome function and integrity. Copyright © 2008 by the Genetics Society of America.