Vacuolar ATPase regulates ureteric bud branching morphogenesis during kidney development.

Our studies have established that ureteric bud (UB) prorenin receptor (PRR/ATP6AP2), an accessory subunit of the vacuolar H+-ATPase (V-ATPase), is critical for normal UB branching. Here, we tested the hypothesis that V-ATPase activity, acidosis, and UB cell intracellular pH (pHi) regulate UB branching morphogenesis during kidney development. The effect of specific V-ATPase inhibitor Bafilomycin, hypercapnic (high CO2), and metabolic (low [Formula: see text]) acidosis on UB branching was determined in whole intact E12.5 Hoxb7GFP+ mouse kidneys grown ex vivo by time-lapse photomicroscopy. The effect of Bafilomycin on UB cell migration in vitro was examined using a transwell migration assay (n = 3 wells/treatment group). The presence of V-ATPase and Na+-H+ exchanger (NHE) activity in UB cells was investigated by measurements of intracellular pH (pHi). The ability of UB cells to regulate cell pHi in vitro was determined by measurements of Na-dependent and Na-independent pHi recovery from acid loads. The mean number of UB cells that migrated through the membrane after 24-h culture was reduced with Bafilomycin compared with control. Treatment with Bafilomycin, hypercapnic acidosis (induced by high CO2), or metabolic acidosis (induced by low [Formula: see text] concentration) in the culture media caused a marked reduction in the number of UB tips compared with control. We conclude that intact V-ATPase activity is essential for normal UB branching during kidney development. V-ATPase-dependent reduction in UB cell pHi is likely a cause of decreasing UB branching by inhibiting directional movements of UB cells.NEW & NOTEWORTHY Disruption of normal kidney development results in a spectrum of congenital anomalies of the kidney and urinary tract (CAKUT), the major cause of end-stage kidney disease in children. We demonstrate that acidosis, kidney cell intracellular pH, and activity of V-ATPase pump are essential for normal kidney development.