PAR1-mediated Non-periodical Synchronized Calcium Oscillations in human Mesangial Cells

Abstract Mesangial cells offer structural support to the glomerular tuft and regulate glomerular capillary flow through their contractile capabilities. These cells undergo phenotypic changes, such as proliferation and mesangial expansion, resulting in abnormal glomerular tuft formation and reduced capillary loops. Such adaptation to the changing environment is commonly associated with various glomerular diseases, including diabetic nephropathy and glomerulonephritis. Thrombin-induced mesangial remodeling was found in diabetic patients, and expression of the corresponding protease-activated receptors (PARs) in the renal mesangium was reported. However, the functional PAR-mediated signaling in mesangial cells was not examined. This study investigated protease-activated mechanisms regulating mesangial cell calcium waves that may play an essential role in the mesangial proliferation or constriction of the arteriolar cells. Our results indicate that coagulation proteases like thrombin induce synchronized oscillations in cytoplasmic Ca2+ concentration of mesangial cells. The oscillations required PAR1 GPCRs-related activation, but not a PAR4, and were further mediated presumably through store-operated calcium entry and TRPC3 channel activity. Understanding thrombin signaling pathways and their relation to mesangial cells' contractile or synthetic (proliferative) phenotype may play a role in the development of chronic kidney disease and requires further investigation.