Lipophilic natural compounds (n‐3 polyunsaturated fatty acids) modulate plasma membrane organization in mouse CD4 + T cells (975.1)

We have previously shown that n‐3 polyunsaturated fatty acids (PUFA) increase plasma membrane lipid order in mouse CD4 + T cells, blocking T cell activation. Since lipid rafts are important for T cell activation, we hypothesized that n‐3 PUFA perturb CD4 + T cell plasma membrane lipid rafts. To probe the mechanism for n‐3 PUFA action, CD4 + T cells from Fat‐1 transgenic mice (enriched in n‐3 PUFA), were transduced with fluorescence energy resonance transfer (FRET) lipid raft probes Lck(N10) and LAT(ΔCP), and non‐raft probe Src(N15). Co‐clustering of Lck(N10) and LAT(ΔCP) in CD4 + T cells increased in the presence of n‐3 PUFA as assessed by FRET; conversely n‐3 PUFA did not alter the co‐clustering between Lck(N10) and Src(N15). These data demonstrate that n‐3 PUFA modulate membrane nano‐organization in CD4 + T cells. We have also previously demonstrated that n‐3 PUFA decrease the mass of phosphatidylinositol‐(4,5)‐bisphosphate [PI(4,5)P 2 ] in CD4 + T cells. Since discrete pools of PI(4,5)P 2 may exist in the plasma membrane, we also determined whether n‐3 PUFA modulate spatial organization of PI(4,5)P 2 relative to raft and non‐raft domains. Co‐clustering of PH(PLC‐δ1), a PI(4,5)P 2 probe, and Lck(N10) or LAT(∆CP) was not affected by n‐3 PUFA; however, co‐clustering of PH(PLC‐δ1) and Src(N15) showed a decrease in the presence of n‐3 PUFA, suggesting that n‐3 PUFA alter the spatial organization of PI(4,5)P 2 . Grant Funding Source : Supported by NSERC and NIH