A Hierarchical Model of Purinergic Receptor Activation in Bronchial Epithelial Cells

Purinergic signaling coordinates diverse epithelial responses to extracellular nucleotides such as ATP, ADP, and UDP. Although many epithelial cell types co-express multiple P2 receptors, the logic by which these receptors integrate nucleotide signals has remained unclear. Here, using primary human airway epithelial cells as a model, we reveal a hierarchical system in which P2Y ₂ functions as a central licensing receptor that both enables and constrains downstream activation of P2Y ₆ and P2Y ₁₂ . Molecular analysis, calcium assays, and pharmacological profiling show that P2Y ₆ and P2Y ₁₂ exhibit intrinsic activity when co-express to P2Y ₂ but in turn lose responsiveness to their specific agonists upon upstream activation of P2Y ₂ . This gating mechanism filters background noise by secondary nucleotides and enforces contextual control over downstream signaling. These findings uncover a previously unrecognized principle of purinergic receptor coordination that may apply broadly across epithelial systems, and offer new insight into nucleotide signaling as a therapeutic target.