Distal renal tubular acid-base homeostasis in health and disease.

The kidneys’ acid-secreting cells are failing to deliver their molecular pumps to the right place, and this breakdown in cellular logistics is now the target of a new research programme. This matters because the kidney’s ability to control acid-base balance depends on two proteins—AE1 and the H⁺-ATPase proton pump—working together in specialised cells called intercalated cells. When these proteins are misrouted or misassembled, the result is distal renal tubular acidosis, a condition that can cause kidney stones, growth failure, and bone disease. Despite decades of genetic discovery, the molecular trafficking pathways that get these proteins to the correct membrane remain poorly understood. The programme will use a newly available mouse model carrying a mutation in the a4 subunit of the proton pump, alongside cultured human kidney cells, to map exactly how AE1 and the pump are sorted within the cell. It will also investigate urinary exosomes—tiny membrane-bound particles shed into urine—which may modulate calcification in the kidney tract when urine pH goes wrong. A bank of patient urine samples is already in place for these studies. If successful, this work could reveal new biomarkers for stone-forming disorders and explain why some people with acid-base disturbances develop kidney stones while others do not. The research is primarily fundamental cell biology, but understanding how these proteins navigate the cell’s internal sorting system could eventually point to drug targets for preventing renal calcification.