Role of PTH in the Renal Handling of Phosphate

Parathyroid hormone (PTH) is one of the primary phosphaturic hormones in the body. The type IIa sodium-phosphate cotransporter (Npt2a) is expressed in the apical membrane of the renal proximal tubule and is responsible for the reabsorption of the majority of the filtered load of phosphate. PTH acutely induces phosphaturia through the rapid stimulation of endocytosis of Npt2a and its subsequent lysosomal degradation. This review focuses on the homeostatic mechanisms underlying serum phosphate, with particular focus on the regulation of the phosphate transporter Npt2a by PTH within the renal proximal tubule. Additionally, the proximal tubular PTH-stimulated signaling events as they relate to PTH-induced phosphaturia are also highlighted. Lastly, we discuss recent findings by our lab concerning novel regulatory mechanisms of PTH-mediated reductions in Npt2a expression