Flotillin-1 stabilizes caveolin-1 in intestinal epithelial cells

• Type of Material: Article
• Authors: Elena V. Vassilieva, Emory University; Andrei I. Ivanov, University of Rochester; Asma Nusrat, Emory University
• Language: English
• Date: 2009-02-06
• Publisher: Elsevier: 12 months
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2009, Elsevier
• License: Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1016/j.bbrc.2008.12.118
• Title of Journal or Parent Work: Biochemical and Biophysical Research Communications
• ISSN: 0006-291X
• Volume: 379
• Issue: 2
• Start Page: 460
• End Page: 465
• Grant/Funding Information: This work was supported by grants from the NIH (DK 59888) (A.N.) and CCFA (A.I.).
• Keywords: Epithelial cells; Lactosyl ceramide internalization; Lysosomal degradation; Lipid rafts
• Research Categories: Biophysics, General; Chemistry, Biochemistry; Health Sciences, Immunology

Abstract

Flotillins and caveolins represent two types of resident proteins associated with lipid rafts in mammalian cells, however, their possible cross-talk in regulating lipid raft functions remains poorly understood. In this report, we observed that siRNA-mediated down-regulation of flotillin-1 expression which disrupted lipid raft-mediated endocytosis of BODIPY FL C5-lactosylceramide also substantially decreased caveolin-1 level in SK-CO15 human intestinal epithelial cells. The decrease in caveolin-1 expression appeared to be specific for flotillin-1 knock-down and was not observed after down-regulation of flotillin-2. The decrease in caveolin-1 level in flotillin-1-depleted cells was not due to suppression of its mRNA synthesis and was not mimicked by cholesterol depletion of SK-CO15 cells. Furthermore, flotillin-1 dependent down-regulation of caveolin-1 was reversed after cell exposure to lysosomal inhibitor, chloroquine but not proteosomal inhibitor, MG262. Our data suggest that flotillin-1 regulates caveolin-1 level by preventing its lysosomal degradation in intestinal epithelial cells.