The many roles of the calcium-sensing receptor in the kidney.

The calcium-sensing receptor (CaSR) is a central regulator of renal mineral homeostasis and tubular function. Since the discovery of its expression in the kidney, numerous studies have demonstrated that its actions are finely distributed along the nephron. Through these segment-specific mechanisms, the CaSR orchestrates diverse physiological processes: contributes to the integrity of the filtration barrier, regulates proximal and distal tubular handling of essential ions such as calcium, magnesium, and sodium, and influences water transport and acid-base balance, integrating mineral metabolism with overall renal function. Collectively, these functions establish the CaSR as a key integrator of nephron physiology, linking calcium sensing to ion transport, cellular signaling, and renal protection under both physiological and pathological conditions.