Sodium-dependent phosphate cotransporter 2A (NaPi-IIa) (NaPi-IIa)

The Sodium-dependent phosphate cotransporter 2A (NaPi-IIa), encoded by the SLC34A1 gene, is a transmembrane protein primarily expressed on the apical membrane of renal proximal tubule cells (UniProt: P41414). It plays a dominant role in systemic phosphate homeostasis by mediating the reabsorption of approximately 70-80% of filtered inorganic phosphate from the tubular fluid (PubMed: 29133533). The activity and surface expression of NaPi-IIa are tightly regulated by parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), and dietary phosphate intake (PubMed: 22461035). Dysregulation or genetic mutations in SLC34A1 can lead to disorders such as hypophosphatemic rickets, nephrolithiasis, and Fanconi syndrome (PubMed: 26838947). In patients with chronic kidney disease (CKD), targeting NaPi-IIa with pharmacological inhibitors is an emerging strategy to treat hyperphosphatemia by promoting urinary phosphate excretion (PubMed: 30655315). Experimental inhibitors like PF-06869206 have demonstrated the potential to lower serum phosphate levels independently of intestinal phosphate absorption (PubMed: 33158958).

Other names

SLC34A1NPT2aSodium/phosphate cotransporter 2ASolute carrier family 34 member 1Na(+)-dependent phosphate cotransporter 2a

Direct inhibition of the sodium-coupled transport of inorganic phosphate across the apical membrane of renal proximal tubule cells, thereby increasing renal phosphate clearance.