Regulation of the Skeletal Muscle Ryanodine Receptor/Ca2+ -release Channel RyR1 by S-Palmitoylation

Background: Excitation-contraction coupling in striated muscle requires intracellular Ca2+ release through ryanodine receptor/Ca2+-release channels (RyRs). Results:S-Palmitoylation is a previously unidentified post-translational modification of skeletal muscle RyR1. Diminishing S-palmitoylation significantly diminishes RyR1 activity including stimulus-dependent Ca2+ release. Conclusion:S-Palmitoylation provides a previously unidentified mechanism to regulate Ca2+ flux in skeletal muscle. Significance:S-Palmitoylation is likely to regulate Ca2+ flux in many cell types. The ryanodine receptor/Ca2+-release channels (RyRs) of skeletal and cardiac muscle are essential for Ca2+ release from the sarcoplasmic reticulum that mediates excitation-contraction coupling. It has been shown that RyR activity is regulated by dynamic post-translational modifications of Cys residues, in particular S-nitrosylation and S-oxidation. Here we show that the predominant form of RyR in skeletal muscle, RyR1, is subject to Cys-directed modification by S-palmitoylation. S-Palmitoylation targets 18 Cys within the N-terminal, cytoplasmic region of RyR1, which are clustered in multiple functional domains including those implicated in the activity-governing protein-protein interactions of RyR1 with the L-type Ca2+ channel Ca(V)1.1, calmodulin, and the FK506-binding protein FKBP12, as well as in hot spot regions containing sites of mutations implicated in malignant hyperthermia and central core disease. Eight of these Cys have been identified previously as subject to physiological S-nitrosylation or S-oxidation. Diminishing S-palmitoylation directly suppresses RyR1 activity as well as stimulus-coupled Ca2+ release through RyR1. These findings demonstrate functional regulation of RyR1 by a previously unreported post-translational modification and indicate the potential for extensive Cys-based signaling cross-talk. In addition, we identify the sarco/endoplasmic reticular Ca2+-ATPase 1A and the (1S) subunit of the L-type Ca2+ channel Ca(V)1.1 as S-palmitoylated proteins, indicating that S-palmitoylation may regulate all principal governors of Ca2+ flux in skeletal muscle that mediates excitation-contraction coupling.