Endocytic trafficking and signaling of proton‐sensing receptor GPR65

Abstract

Proton-sensing G-protein coupled receptors (GPCRs) allow cells to sense and respond to changes in extracellular pH. Although pH disturbances have profound effects on cell function and disease progression, little is known about how proton-sensing GPCR activation, trafficking and signaling from distinct intracellular compartments contribute to cellular responses. Here we use GPR65, a proton-sensing GPCR that contributes to pathological conditions characterized by acidic tissue microenvironments such as cancer and chronic inflammatory conditions, as a prototype to study these questions. We use live imaging of HEK293 cells expressing tagged versions of our protein of interest, GPR65, to visualize receptor trafficking, sorting to intracellular compartments, and receptor activation using signaling and conformational biosensors in real time. Our preliminary results indicate that GPR65 localizes to intracellular compartments at steady state and recruits conformational biosensors to both the plasma membrane and intracellular compartments when exposed to neutral and acidic pH. Characterizing GPR65 trafficking and activation within the endosomal pathway will help us understand how proton-sensing receptors contribute to normal physiology and disease and provide new strategies to treat pathological conditions associated with acidic microenvironments.