Expression data from HMC-1 mast cells

We demonstrate that the G protein Gi3 is the cellular target of the adenosine A3 receptor (A3R). By using a cell permeable peptide comprising the C-terminal end of Gi3 fused to an importation sequence (ALL1) as a selective inhibitor of Gi3 signaling, we show that by coupling to Gi3, the A3R stimulates multiple signaling pathways in human mast cells, leading to upregulation of cytokines, chemokines and growth factors.Following contact with activated T cell membranes, endogenous adenosine binds to and activates the A3R, resulting in Gi3-mediated signaling. Specifically, the majority of ERK1/2 signaling initiated by contact with activated T cell membranes, is mediated by Gi3, giving rise to ALL1-inhibitable cellular responses. These results unveil the physiological GPCR that couples to Gi3 and establish the important role played by this G-protein in inflammatory conditions that involve adenosine-activated mast cells.

12

Baram D, Dekel O, Mekori YA, Sagi-Eisenberg R