Regulator of G-protein signaling protein 2 modulates purinergic calcium and ciliary beat frequency responses in airway epithelia

In ciliated airway epithelial cells, purinergic stimulation increases both intracellular calcium ([Ca²⁺]_i) and ciliary beat frequency (CBF). Because regulator of G-protein signaling protein 2 (RGS2) terminates Gαq-mediated phospholipase C activation, we examined its role in regulating purinergic signaling in human and ovine airway epithelial cells. RT-PCR of both human and ovine epithelial cell RNA yielded fragments of expected size (∼ 491 bp) and sequence, confirming RGS2 message. Immunofluorescence demonstrated RGS2 protein expression in cultured airway epithelial cells of both species. Overexpression of an EGFP-RGS2 fusion protein (increasing RGS2 protein levels 1.8 times control, n = 28 cells) resulted in a reduced [Ca²⁺]_i and CBF response to 10 μM ATP (human: 58 ± 9% and 49 ± 8% lower, respectively; n = 8 measurements, 4 cells; ovine: 56 ± 12% and 53 ± 16% lower, respectively; n = 5 measurements, 4 cells). Reducing RGS2 protein levels using antisense oligonucleotides increased the response of both [Ca²⁺]_i and CBF to ATP in human cells by 57 ± 10% and 47 ± 11%, respectively (n = 10 measurements, 6 cells), and in ovine cells by 88 ± 13% and 48 ± 9%, respectively (n = 10 measurements, 5 cells). These data provide functional evidence that RGS2 modulates purinergic signaling in human and ovine ciliated airway epithelial cells.