Coincidence Detection of Membrane Stretch and Extracellular pH by the Proton-Sensing Receptor OGR1 (GPR68)

Abstract

Highlights d OGR1 (aka GPR68) requires cell stretch and extracellular protons to activate d Cell stretch and extracellular acidosis synergistically promote OGR1 signaling d Cell-stretch-mediated actin polymerization is crucial for OGR1 activity d Actin depolymerization limits how long OGR1 stays responsive after cell stretch SUMMARYThe physical environment critically affects cell shape, proliferation, differentiation, and survival by exerting mechanical forces on cells. These forces are sensed and transduced into intracellular signals and responses by cells. A number of different membrane and cytoplasmic proteins have been implicated in sensing mechanical forces, but the picture is far from complete, and the exact transduction pathways remain largely elusive. Furthermore, mechanosensation takes place alongside chemosensation, and cells need to integrate physical and chemical signals to respond appropriately and ensure normal tissue and organ development and function. Here, we report that ovarian cancer G protein coupled receptor 1 (OGR1) (aka GPR68) acts as coincidence detector of membrane stretch and its physiological ligand, extracellular H + . Using fluorescence imaging, substrates of different stiffness, microcontact printing methods, and cell-stretching techniques, we show that OGR1 only responds to extracellular acidification under conditions of membrane stretch and vice versa. The level of OGR1 activity mirrors the extent of membrane stretch and degree of extracellular acidification. Furthermore, actin polymerization in response to membrane stretch is critical for OGR1 activity, and its depolymerization limits how long OGR1 remains responsive following a stretch event, thus providing a ''memory'' for past stretch. Cells experience changes in membrane stretch and extracellular pH throughout their lifetime. Because OGR1 is a widely expressed receptor, it represents a unique yet widespread mechanism that enables cells to respond dynamically to mechanical and pH changes in their microenvironment by integrating these chemical and physical stimuli at the receptor level. Current Biology 28, 3815-3823, December 3, 2018 ª 2018 Elsevier Ltd. 3815 FIJI NIH https://fiji.sc/ Driver software for custom built stretch machine Zaber Console https://www.zaber.com/zaber-software e1 Current Biology 28, 3815-3823.e1-e4, December 3, 2018

Ion current and action potential alterations in peripheral neurons subject to uniaxial strain

“…Cells were deformed using a custom‐built substrate stretching device (Figure ), delivering uniaxial strain to cells cultured on ultrathin (50–100 µm) polydimethylsiloxane substrates (Silex, UK), and allowing for simultaneous high‐resolution microscopy and electrophysiological recording previously used in cell‐stretching experiments aimed at discerning the response of cells to membrane stretch (Wei et al, ). F11 cells were seeded on deformable substrates at 5,000 cells/substrate to allow for cell proliferation during differentiation.…”

GPR68: An Emerging Drug Target in Cancer

“…In addition to its ability to sense protons (H + ), GPR68 was recently shown to be a mechanosensor of shear stress in human and mouse vascular endothelial cells [56] and of stretch in other cell types [57]. Mechanosensing of shear stress required the presence of H + while for mechanosensing of stretch, GPR68 was proposed to be a coincidence detector for membrane stretch and extracellular H + [56,57]. GPR68 KO mice have lower systolic blood pressure than WT mice but without altered diastolic pressure, mean arterial pressure, or heart rate.…”

Coupling Metastasis to pH-Sensing GPR68 Using a Novel Small Molecule Inhibitor

“…In Xenopus, v-atpase regulates pH in a regional manner to affect craniofacial morphogenesis (Adams et al, 2006;Vandenberg et al, 2011) . Notably, recent studies of GPR68 have shown that the receptor senses flow and stretch (Wei et al, 2018;Xu et al, 2018) . However, responses to both stimuli are dependent on mildly acidic conditions.…”