Physiological regulation of renal sodium-dependent phosphate cotransporters.
The physiological regulation of renal Pi reabsorption is mediated by renal type II Na/Pi cotransporters (type IIa and type IIc). The type IIa transporter is regulated, among other factors, by dietary Pi intake and parathyroid hormone (PTH). The PTH-induced inhibition of Pi reabsorption is mediated by endocytosis of the type IIa transporter from the brush-border membrane and subsequent lysosomal degradation. Type IIa is part of the heteromeric protein complexes organized by PDZ proteins. Furthermore, during Pi depletion the type IIc Na/Pi cotransporter is induced in the apical membrane of proximal tubular cells. The type IIc transporter is also regulated by PTH via internalization, but by a vesicular transport pathway distinct from that used by the type IIc transporter. Studying the mechanisms of type IIa and type IIc transporters has increased the understanding of the control of proximal tubular Pi handling and thus of overall Pi homeostasis.
Miyamoto
Ken-ichi
K
Nutritional Science, Department of Nutrition, School of Medicine, Tokushima University, Tokushima, 770-8503 Japan. miyamoto@nutr.med.tokushima-u.ac.jp
Segawa
Hiroko
H
Ito
Mikiko
M
Kuwahata
Masashi
M
D000818:Animals; D006706:Homeostasis; D006801:Humans; D007668:Kidney / Q000502:physiology*; D008871:Microvilli; D010281:Parathyroid Hormone / Q000494:pharmacology; D028061:Phosphate Transport Proteins / Q000502:physiology*; D012377:Rodentia; D050608:Sodium-Phosphate Cotransporter Proteins; D050610:Sodium-Phosphate Cotransporter Proteins, Type II; D050613:Sodium-Phosphate Cotransporter Proteins, Type IIa; D027981:Symporters / Q000494:pharmacology*
D010281:Parathyroid Hormone; D028061:Phosphate Transport Proteins; C493554:SLC34A1 protein, human; D050608:Sodium-Phosphate Cotransporter Proteins; D050610:Sodium-Phosphate Cotransporter Proteins, Type II; D050613:Sodium-Phosphate Cotransporter Proteins, Type IIa; D027981:Symporters