Inhibition of caveolar uptake, SV40 infection, and beta1-integrin signaling by a nonnatural glycosphingolipid stereoisomer.
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.
Singh
Raman Deep
RD
Department of Biochemistry and Molecular Biology, Thoracic Diseases Research Unit, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
Holicky
Eileen L
EL
Cheng
Zhi-jie
ZJ
Kim
Seong-Youl
SY
Wheatley
Christine L
CL
Marks
David L
DL
Bittman
Robert
R
Pagano
Richard E
RE
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*
D015703:Antigens, CD; D006028:Glycosphingolipids; D019012:Integrin beta1; D007790:Lactosylceramides; D034741:RNA, Small Interfering; C009744:CDw17 antigen