title: Inhibition of caveolar uptake, SV40 infection, and beta1-integrin signaling by a nonnatural glycosphingolipid stereoisomer.
abstract: Caveolar endocytosis is an important mechanism for the uptake of certain pathogens and toxins and also plays a role in the internalization of some plasma membrane (PM) lipids and proteins. However, the regulation of caveolar endocytosis is not well understood. We previously demonstrated that caveolar endocytosis and beta1-integrin signaling are stimulated by exogenous glycosphingolipids (GSLs). In this study, we show that a synthetic GSL with nonnatural stereochemistry, beta-D-lactosyl-N-octanoyl-L-threo-sphingosine, (1) selectively inhibits caveolar endocytosis and SV40 virus infection, (2) blocks the clustering of lipids and proteins into GSLs and cholesterol-enriched microdomains (rafts) at the PM, and (3) inhibits beta1-integrin activation and downstream signaling. Finally, we show that small interfering RNA knockdown of beta1 integrin in human skin fibroblasts blocks caveolar endocytosis and the stimulation of signaling by a GSL with natural stereochemistry. These experiments identify a new compound that can interfere with biological processes by inhibiting microdomain formation and also identify beta1 integrin as a potential mediator of signaling by GSLs.
authors: Department of Biochemistry and Molecular Biology, Thoracic Diseases Research Unit, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
authors: Raman Deep
authors: RD
authors: Singh
authors: Eileen L
authors: EL
authors: Holicky
authors: Zhi-jie
authors: ZJ
authors: Cheng
authors: Seong-Youl
authors: SY
authors: Kim
authors: Christine L
authors: CL
authors: Wheatley
authors: David L
authors: DL
authors: Marks
authors: Robert
authors: R
authors: Bittman
authors: Richard E
authors: RE
authors: Pagano
mesh_terms: D015703:Antigens, CD / Q000737:chemistry / Q000494:pharmacology*; D021941:Caveolae / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D006028:Glycosphingolipids / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D019012:Integrin beta1 / Q000235:genetics / Q000378:metabolism*; D007790:Lactosylceramides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism; D008968:Molecular Conformation; D034741:RNA, Small Interfering; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013539:Simian virus 40 / Q000187:drug effects / Q000502:physiology*; D013237:Stereoisomerism; D053586:Virus Internalization / Q000187:drug effects*
chemical_list: D015703:Antigens, CD; D006028:Glycosphingolipids; D019012:Integrin beta1; D007790:Lactosylceramides; D034741:RNA, Small Interfering; C009744:CDw17 antigen