The role of P2Y14 and other P2Y receptors in degranulation of human LAD2 mast cells

摘要

Mast cell degranulation affects many conditions, e.g., asthma and urticaria. We explored the potential role of the P2Y₁₄ receptor (P2Y₁₄R) and other P2Y subtypes in degranulation of human LAD2 mast cells. All eight P2YRs were expressed at variable levels in LAD2 cells (quantitative real-time RT-PCR). Gene expression levels of ADP receptors, P2Y₁R, P2Y₁₂R, and P2Y₁₃R, were similar, and P2Y₁₁R and P2Y₄R were highly expressed at 5.8- and 3.8-fold of P2Y₁R, respectively. Least expressed P2Y₂R was 40-fold lower than P2Y₁R, and P2Y₆R and P2Y₁₄R were ≤50?% of P2Y₁R. None of the native P2YR agonists alone induced β-hexosaminidase (β-Hex) release, but some nucleotides significantly enhanced β-Hex release induced by C3a or antigen, with a rank efficacy order of ATP??UDPG?≥?ADP??UDP, UTP. Although P2Y₁₁R and P2Y₄R are highly expressed, they did not seem to play a major role in degranulation as neither P2Y₄R agonist UTP nor P2Y₁₁R agonists ATPγS and NF546 had a substantial effect. P2Y₁R-selective agonist MRS2365 enhanced degranulation, but ~1,000-fold weaker compared to its P2Y₁R potency, and the effect of P2Y₆R agonist 3-phenacyl-UDP was negligible. The enhancement by ADP and ATP appears mediated via multiple receptors. Both UDPG and a synthetic agonist of the P2Y₁₄R, MRS2690, enhanced C3a-induced β-Hex release, which was inhibited by a P2Y₁₄R antagonist, specific P2Y₁₄R siRNA and pertussis toxin, suggesting a role of P2Y₁₄R activation in promoting human mast cell degranulation.