A stomatin and a degenerin interact in lipid rafts of the nervous system of Caenorhabditis elegans

1 Departments of Anesthesiology and Genetics, University Hospitals and Case Western Reserve University, Cleveland, Ohio 44106; and 2 Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37323-8240 Submitted 6 May 2003 ; accepted in final form 5 April 2004 In Caenorhabditis elegans , the gene unc-1 controls anesthetic sensitivity and normal locomotion. The protein UNC-1 is a close homolog of the mammalian protein stomatin and is expressed primarily in the nervous system. Genetic studies in C. elegans have shown that the UNC-1 protein interacts with a sodium channel subunit, UNC-8. In humans, absence of stomatin is associated with abnormal sodium and potassium levels in red blood cells. Stomatin also has been postulated to participate in the formation of lipid rafts, which are membrane microdomains associated with protein complexes, cholesterol, and sphingolipids. In this study, we isolated a low-density, detergent-resistant fraction from cell membranes of C. elegans. This fraction contains cholesterol, sphingolipids, and protein consistent with their identification as lipid rafts. We then probed Western blots of protein from the rafts and found that the UNC-1 protein is almost totally restricted to this fraction. The UNC-8 protein is also found in rafts and coimmunoprecipitates UNC-1. A second stomatin-like protein, UNC-24, also affects anesthetic sensitivity, is found in lipid rafts, and regulates UNC-1 distribution. Mutations in the unc-24 gene alter the distribution of UNC-1 in lipid rafts. Each of these mutations alters anesthetic sensitivity in C. elegans . Because lipid rafts contain many of the putative targets of volatile anesthetics, they may represent a novel class of targets for volatile anesthetics. genetics; anesthetic; membrane; trafficking Address for reprint requests and other correspondence: P. Morgan, Dept. of Anesthesiology, Univ. Hospitals, 11100 Euclid Ave., Cleveland, OH 44106 (E-mail: philip.morgan{at}uhhs.com ).