Inhibition of protein palmitoylation, raft localization, and T cell signaling by 2-bromopalmitate and polyunsaturated fatty acids.
The ability of the Src family kinases Fyn and Lck to participate in signaling through the T cell receptor is critically dependent on their dual fatty acylation with myristate and palmitate. Here we identify a palmitate analog, 2-bromopalmitate, that effectively blocks Fyn fatty acylation in general and palmitoylation in particular. Treatment of COS-1 cells with 2-bromopalmitate blocked myristoylation and palmitoylation of Fyn and inhibited membrane binding and localization of Fyn to detergent-resistant membranes (DRMs). In Jurkat T cells, 2-bromopalmitate blocked localization of the endogenous palmitoylated proteins Fyn, Lck, and LAT to DRMs. This resulted in impaired signaling through the T cell receptor as evidenced by reductions in tyrosine phosphorylation, calcium release, and activation of mitogen-activated protein kinase. We also examined the ability of long chain polyunsaturated fatty acids (PUFAs) to inhibit protein fatty acylation. PUFAs have been reported to inhibit T cell signaling by excluding Src family kinases from DRMs. Here we show that the PUFAs arachidonic acid and eicosapentaenoic acid inhibit Fyn palmitoylation and consequently block Fyn localization to DRMs. We propose that inhibition of protein palmitoylation represents a novel mechanism by which PUFAs exert their immunosuppressive effects.
Webb
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Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
Hermida-Matsumoto
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L
Resh
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MD
D000215:Acylation / Q000187:drug effects; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D019556:COS Cells; D002451:Cell Compartmentation; D004789:Enzyme Activation; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D006801:Humans; D019169:Jurkat Cells; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000302:isolation & purification / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010168:Palmitates / Q000494:pharmacology*; D019308:Palmitic Acid / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D011518:Proto-Oncogene Proteins / Q000302:isolation & purification / Q000378:metabolism; D051076:Proto-Oncogene Proteins c-fyn; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D019061:src-Family Kinases / Q000302:isolation & purification / Q000378:metabolism*
D005231:Fatty Acids, Unsaturated; D010168:Palmitates; D011518:Proto-Oncogene Proteins; C022776:2-bromopalmitate; D019308:Palmitic Acid; C494957:FYN protein, human; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051076:Proto-Oncogene Proteins c-fyn; D019061:src-Family Kinases; D020928:Mitogen-Activated Protein Kinases