Abstract
Caveolae are plasma membrane domains involved in the uptake of certain pathogens and toxins. Internalization of some cell surface integrins occurs via caveolae suggesting caveolae may play a crucial role in modulating integrin-mediated adhesion and cell migration. Here we demonstrate a critical role for gangliosides (sialo-glycosphingolipids) in regulating caveolar endocytosis in human skin fibroblasts. Pretreatment of cells with endoglycoceramidase (cleaves glycosphingolipids) or sialidase (modifies cell surface gangliosides and glycoproteins) selectively inhibited caveolar endocytosis by >70%, inhibited the formation of plasma membrane domains enriched in sphingolipids and cholesterol ('lipid rafts'), reduced caveolae and caveolin-1 at the plasma membrane by approximately 80%, and blunted activation of β1-integrin, a protein required for caveolar endocytosis in these cells. These effects could be reversed by a brief incubation with gangliosides (but not with asialo-gangliosides or other sphingolipids) at 10°C, suggesting that sialo-lipids are critical in supporting caveolar endocytosis. Endoglycoceramidase treatment also caused a redistribution of focal adhesion kinase, paxillin, talin, and PIP Kinase Iγ away from focal adhesions. The effects of sialidase or endoglycoceramidase on membrane domains and the distribution of caveolin-1 could be recapitulated by β1-integrin knockdown. These results suggest that both gangliosides and β1-integrin are required for maintenance of caveolae and plasma membrane domains.
Original language | English (US) |
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Pages (from-to) | 348-360 |
Number of pages | 13 |
Journal | Traffic |
Volume | 11 |
Issue number | 3 |
DOIs | |
State | Published - Mar 2010 |
Keywords
- Caveolar endocytosis
- Caveolin-1
- Endoglycoceramidase
- Focal adhesions
- Glycosphingolipids
- Sialidase
ASJC Scopus subject areas
- Structural Biology
- Biochemistry
- Molecular Biology
- Genetics
- Cell Biology