| Caveolin-1 regulation of dynamin-dependent, raft-mediated endocytosis of cholera toxin-B sub-unit occurs independently of caveolae. | |
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MedLine Citation:
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PMID: 19438805 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
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Ganglioside GM1-bound cholera toxin-B sub-unit (CT-b) enters the cell via clathrin-coated pits and dynamin-independent non-caveolar raft-dependent endocytosis. Caveolin-1 (Cav1), associated with caveolae formation, is a negative regulator of non-caveolar raft-dependent endocytosis. In mammary epithelial tumour cells deficient for Mgat5, Cav1 is stably expressed at levels below the threshold for caveolae formation, forming stable oligomerized Cav1 microdomains or scaffolds that were shown to suppress EGFR signalling and reduce the plasma membrane diffusion rate of both EGFR and CT-b. Below threshold levels of Cav1 also inhibit the dynamin-dependent raft-mediated endocytosis of CT-b to the Golgi indicating that Cav1-negative regulation of raft-dependent endocytosis is caveolae independent. Inhibition of CT-b internalization does not require Cav1 phosphorylation but does require an intact Cav1 scaffolding domain. By flow cytometry, both over-expression of Cav1 and the dynamin K44A mutant block CT-b internalization from the plasma membrane defining a dynamin-dependent raft pathway for CT-b endocytosis in these cells. However, only minimal co-localization between CT-b and Cav1 is observed. These results suggest that Cav1 regulates raft-dependent internalization of CT-b indirectly via a mechanism that requires the Cav1 scaffolding domain and the formation of oligomerized Cav1 microdomains but not caveolae. |
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Authors:
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Patrick Lajoie; Liliana D Kojic; Satra Nim; Lei Li; James W Dennis; Ivan R Nabi |
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Publication Detail:
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Type: Journal Article Date: 2009-03-06 |
Journal Detail:
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Title: Journal of cellular and molecular medicine Volume: 13 ISSN: 1582-4934 ISO Abbreviation: J. Cell. Mol. Med. Publication Date: 2009 Sep |
Date Detail:
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Created Date: 2010-03-03 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 101083777 Medline TA: J Cell Mol Med Country: England |
Other Details:
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Languages: eng Pagination: 3218-25 Citation Subset: IM |
Affiliation:
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Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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