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Lipid Rafts Mediate Ultraviolet Light‐induced Fas Aggregation in M624 Melanoma Cells
Author(s) -
Elyassaki Walid,
Wu Shiyong
Publication year - 2006
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/2005-12-09-ra-748
Subject(s) - lipid raft , ultraviolet light , chemistry , ultraviolet , biophysics , microbiology and biotechnology , biology , biochemistry , materials science , photochemistry , optoelectronics , signal transduction
Ultraviolet light (UV) induces aggregation of Fas‐receptor through a Fas‐ligand‐independent pathway. However, the mechanism of ultraviolet light‐induced Fas‐receptor aggregation is not known. In this report, we show that lipid rafts mediate ultraviolet light‐induced aggregation of Fas. Our data show that UV induces a redistribution of Fas‐receptor in a 25–5% Optiprep continuous gradient. The amount of Fas‐receptor is significantly increased in a gradient fraction that contain lipid rafts and is associated with an increase of FADD and caspase‐8. Our data also show that the active dimeric form of caspase‐8 (p44/p41) is increased in the lipid raft fraction. In addition, our data show that cholesterol, a major component of lipid rafts, is significantly reduced in only the lipid raft fractions after UV‐irradiation. However, ceramide, another major lipid raft component, is increased evenly in all gradient fractions after UV‐irradiation. These results suggest that UV alters the composition of major lipid raft components, which leads to the recruitment of Fas‐receptor and FADD, with subsequent activation of caspase‐8. Based on our results, we propose a novel mechanism by which UV induces apoptosis through a membrane lipid raft‐mediated signaling pathway.