title: Sodium-dependent phosphate cotransporters: lessons from gene knockout and mutation studies.
abstract: Inorganic phosphate (Pi) is an essential physiological compound, highlighted by the syndromes caused by hypo or hyperphosphatemic states. Hyperphosphatemia is associated with ectopic calcification, cardiovascular disease, and increased mortality in patients with chronic kidney disease (CKD). As phosphate control is not efficient with diet or dialysis, oral Pi binders are used in over 90% of patients with renal failure. However, achieving tight control of serum Pi is difficult, and lower levels of serum Pi (severe hypophosphatemia) do not lead to better outcomes. The inhibition of sodium-dependent Pi (NaPi) transporter would be a preferable method to control serum Pi levels in patients with CKD or patients undergoing dialysis. Three types of NaPi transporters (types I-III) have been identified: solute carrier series SLC17A1 (NPT1/NaPi-I/OATv1), SLC34 (NaPi-IIa, NaPi-IIb, NaPi-IIc), and SLC20 (PiT1, PiT2), respectively. Knockout mice have been created for types I-III NaPi transporters. In this review, we discuss the roles of the NaPi transporters in Pi homeostasis.
authors.affiliation: Department of Molecular Nutrition, Institute of Health Biosciences, University of Tokushima Graduate School Tokushima 770-8503, Japan. miyamoto@nutr.med.tokushima-u.ac.jp
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Miyamoto
authors.forename: Sakiko
authors.initials: S
authors.lastname: Haito-Sugino
authors.forename: Shoji
authors.initials: S
authors.lastname: Kuwahara
authors.forename: Akiko
authors.initials: A
authors.lastname: Ohi
authors.forename: Kengo
authors.initials: K
authors.lastname: Nomura
authors.forename: Mikiko
authors.initials: M
authors.lastname: Ito
authors.forename: Masashi
authors.initials: M
authors.lastname: Kuwahata
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Kido
authors.forename: Sawako
authors.initials: S
authors.lastname: Tatsumi
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kaneko
authors.forename: Hiroko
authors.initials: H
authors.lastname: Segawa
mesh_terms: D000818:Animals; D055785:Gene Knockdown Techniques; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D028061:Phosphate Transport Proteins / Q000235:genetics / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*
chemical_list: D028061:Phosphate Transport Proteins; D012964:Sodium