Photolysis of intracellular caged sphingosine‐1‐phosphate causes Ca2+ mobilization independently of G‐protein‐coupled receptors

[摘要]

Sphingosine-1-phosphate (S1P), the product of sphingosine kinase, activates several widely expressed G-protein-coupled receptors (GPCR). S1P might also play a role as second messenger, but this hypothesis has been challenged by recent findings. Here we demonstrate that intracellular S1P can mobilize Ca²⁺ in intact cells independently of S1P-GPCR. Within seconds, S1P generated by the photolysis of caged S1P raised the intracellular free Ca²⁺ concentration in HEK-293, SKNMC and HepG2 cells, in which the response to extracellularly applied S1P was either blocked or absent. Ca²⁺ transients induced by photolysis of caged S1P were caused by Ca²⁺ mobilization from thapsigargin-sensitive stores. These results provide direct evidence for a true intracellular action of S1P.

[学科分类] 生物化学/生物物理

[关键词] Ca2+ mobilization;Photolysis;Sphingosine-1-phosphate;Thapsigargin-sensitive Ca2+ store;[Ca2+]i;cytosolic free Ca2+ concentration;GPCR;G-protein-coupled receptor;HBSS;Hank's balanced salt solution;I Cl;chloride current;IP3;inositol-1;4;5-trisphosphate;PTX;pertussis toxin;S1P;sphingosine-1-phosphate