OSR1-sensitive regulation of Na+/H+ exchanger activity in dendritic cells

The oxidative stress-responsive kinase 1 (OSR1) is activated by WNK (with no K kinases) and in turn stimulates the thiazide-sensitive Na-Cl cotransporter (NCC) and the furosemide-sensitive Na-K-2Cl cotransporter (NKCC), thus contributing to transport and cell volume regulation. Little is known about extrarenal functions of OSR1. The present study analyzed the impact of decreased OSR1 activity on the function of dendritic cells (DCs), antigen-presenting cells linking innate and adaptive immunity. DCs were cultured from bone marrow of heterozygous WNK-resistant OSR1 knockin mice (osrKI) and wild-type mice (osrWT). Cell volume was estimated from forward scatter in FACS analysis, ROS production from 2′,7′-dichlorodihydrofluorescein-diacetate fluorescence, cytosolic pH (pHi) from 2′,7′-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein fluorescence, and Na+/H+ exchanger activity from Na+-dependent realkalinization following ammonium pulse and migration utilizing transwell chambers. DCs expressed WNK1, WNK3, NCC...