Abstract
Glucans are natural product carbohydrates that stimulate immunity. Glucans are internalized by the pattern recognition receptor, Dectin-1. Glucans were thought to be trafficked to phagolysosomes, but this is unproven. We examined the internalization and trafficking of soluble glucans in macrophages. Incubation of macrophages with glucan resulted in internalization of Dectin-1 and glucan. Inhibition of clathrin blocked internalization of the Dectin-1/glucan complex. Lipid raft depletion resulted in decreased Dectin levels and glucan uptake. Once internalized, glucans colocalized with early endosomes at 0 to 15 min, with the Golgi apparatus at 15 min to 24 h, and with Dectin-1 immediately (0 h) and again later (15 min-24 h). Glucans did not colocalize with lysosomes at any time interval examined. We conclude that the internalization of Dectin-1/glucan complexes in macrophages is mediated by clathrin and negatively regulated by lipid rafts and/or caveolin-1. Upon internalization, soluble glucans are trafficked via endosomes to the Golgi apparatus, not lysosomes.
Footnotes
This work was supported, in part, by the National Institutes of Health National Institute of General Medical Sciences [Grant GM53522] (to D.L.W.).
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
ABBREVIATIONS:
- PRR
- pattern recognition receptor
- Syk
- spleen tyrosine kinase
- NF-κB
- nuclear factor κB
- GP
- glucan phosphate
- MβCD
- methyl β cyclodextran
- AF
- Alexa Fluor
- Cav(−/−)
- caveolin-1 knockout
- WT
- wild type
- EEA1
- early endosomal antigen 1
- PBS
- phosphate-buffered saline
- MFI
- mean fluorescent intensity.
- Received May 14, 2012.
- Accepted June 12, 2012.
- Copyright © 2012 by The American Society for Pharmacology and Experimental Therapeutics
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