Essential role of EP3 subtype in prostaglandin E₂-induced adhesion of mouse cultured and peritoneal mast cells to the Arg-Gly-Asp-enriched matrix

Accumulating evidence has indicated that mast cells can modulate a wide variety of immune responses. Migration and adhesion play a critical role in regulation of tissue mast cell function, in particular, under inflammatory conditions. We previously demonstrated that prostaglandin (PG) E₂ stimulates adhesion of a mouse mastocytoma cell line, P-815, to the Arg-Gly-Asp (RGD)-enriched matrix through cooperation between two PGE₂ receptor subtypes: EP3 and EP4 (Hatae N, Kita A, Tanaka S, Sugimoto Y, Ichikawa A. J Biol Chem 278: 17977-17981, 2003). We here investigated PGE₂-induced adhesion of IL-3-dependent bone marrow-derived cultured mast cells (BMMCs). In contrast to the elevated cAMP-dependent adhesion of P-815 cells, EP3-mediated Ca²⁺ mobilization plays a pivotal role in PGE₂-induced adhesion of BMMCs. Adhesion and Ca²⁺ mobilization induced by PGE ₂ were abolished in the Ptger3^-/- BMMCs and were significantly suppressed by treatment with pertussis toxin, a phospholipase C inhibitor, U-73122, and a store-operated Ca²⁺ channel inhibitor, SKF 36965, indicating the involvement of G_i-mediated Ca²⁺ influx. We then investigated PGE₂-induced adhesion of peritoneal mast cells to the RGD-enriched matrix. EP3 subtype was found to be the dominant PGE receptor that expresses in mouse peritoneal mast cells. PGE₂ induced adhesion of the peritoneal mast cells of the Ptger3^+/+ mice, but not that of the Ptger3^-/- mice. In rat peritoneal mast cells, PGE ₂ or an EP3 agonist stimulated both Ca²⁺ mobilization and adhesion to the RGD-enriched matrix. These results suggested that the EP3 subtype plays a pivotal role in PGE₂-induced adhesion of murine mast cells to the RGD-enriched matrix through Ca²⁺ mobilization.