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A new raft tool

Lipid rafts - ordered membrane microdomains enriched in sphingolipids, cholesterol and GPI-anchored proteins - play important roles in membrane trafficking and signalling. In mast cells, for example, signalling through the IgE receptor FcRI appears to require coalescence of lipid rafts, which allows the receptor to switch on the Src-family kinase Lyn. Barbara Baird and co-workers have now developed a new tool for analysis of raft function: short-chain ceramides, membrane-permeant molecules that are often used to mimic the naturally occurring long-chain ceramides that cells generate by hydrolysing sphingomyelin. The authors show that C₂-ceramide and C₆-ceramide disrupt lipid rafts: they decrease fluorescence anisotropy (a measurement of membrane order) in membrane vesicles and reduce fluorescence resonance energy transfer (FRET) between raft-associated molecules in intact cells (see p. 3177). Baird and co-workers then use these novel inhibitors to dissect IgE/FcR signalling, demonstrating that they cause similar inhibition of FcRI-induced Ca²⁺ mobilization and phospholipase D (PLD) activation. Finally, they show that the PLD inhibitor n-butanol also blocks both Ca²⁺ mobilization and PLD. Their findings thus not only reveal a new raft inhibitor, but also place PLD upstream of antigen-stimulated Ca²⁺ mobilization in the IgE/FcR signalling pathway.

Related articles in JCS:

Disruption of lipid order by short-chain ceramides correlates with inhibition of phospholipase D and downstream signaling by FcRI

Arun Gidwani, H. Alex Brown, David Holowka, and Barbara Baird
JCS 2003 116: 3177-3187. [Abstract] [Full Text]  

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JCS Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Search for Related Content