Visualization of intracellular ATP dynamics in the whole kidney under pathophysiological conditions using the kidney slice culture system

Abstract

ATP depletion plays a central role in the pathogenesis of kidney diseases. Recently, we reported spatiotemporal intracellular ATP dynamics during ischemia reperfusion (IR) using GO-ATeam2 mice systemically expressing an ATP biosensor. However, observation from the kidney surface did not allow visualization of deeper nephrons or accurate evaluation of ATP synthesis pathways. Here we established a novel ATP imaging system using slice culture of GO-ATeam2 mouse kidneys, evaluated ATP synthesis pathway, and analyzed intracellular ATP dynamics using ex vivo IR and cisplatin nephropathy models. We demonstrated that proximal tubules (PTs) were strongly dependent on oxidative phosphorylation (OXPHOS), whereas podocytes relied on both OXPHOS and glycolysis using ATP synthesis inhibitors. We also confirmed that the ex vivo IR model could recapitulate ATP dynamics in vivo; ATP recovery in PTs after reperfusion varied depending on ischemia length, whereas ATP in distal tubules (DTs) recovered well even after long ischemia. After cisplatin administration, ATP levels in PTs decreased first, followed by a decrease in DTs. An organic cation transporter 2 inhibitor suppressed cisplatin uptake in kidney slices, leading to better ATP recovery in PTs, but not in DTs. Finally, we confirmed that a mitochondria protection reagent delayed cisplatin-induced ATP decrease in PTs. This novel system may provide new insights into the energy dynamics and pathogenesis of kidney disease.