title: Relationship between sodium-dependent phosphate transporter (NaPi-IIc) function and cellular vacuole formation in opossum kidney cells.
abstract: NaPi-IIc/SLC34A3 is a sodium-dependent inorganic phosphate (Pi) transporter in the renal proximal tubules and its mutations cause hereditary hypophosphatemic rickets with hypercalciuria (HHRH). In the present study, we created a specific antibody for opossum SLC34A3, NaPi-IIc (oNaPi-IIc), and analyzed its localization and regulation in opossum kidney cells (a tissue culture model of proximal tubular cells). Immunoreactive oNaPi-IIc protein levels increased during the proliferative phase and decreased during differentiation. Moreover, stimulating cell growth upregulated oNaPi-IIc protein levels, whereas suppressing cell proliferation downregulated oNaPi-IIc protein levels. Immunocytochemistry revealed that endogenous and exogenous oNaPi-IIc proteins localized at the protrusion of the plasma membrane, which is a phosphatidylinositol 4,5-bisphosphate (PIP2) rich-membrane, and at the intracellular vacuolar membrane. Exogenous NaPi-IIc also induced cellular vacuoles and localized in the plasma membrane. The ability to form vacuoles is specific to electroneutral NaPi-IIc, and not electrogenic NaPi-IIa or NaPi-IIb. In addition, mutations of NaPi-IIc (S138F and R468W) in HHRH did not cause cellular PIP2-rich vacuoles. In conclusion, our data anticipate that NaPi-IIc may regulate PIP2 production at the plasma membrane and cellular vesicle formation.
authors.affiliation: Department of Molecular Nutrition, University of Tokushima Graduate School.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Shiozaki
authors.forename: Hiroko
authors.initials: H
authors.lastname: Segawa
authors.forename: Saori
authors.initials: S
authors.lastname: Ohnishi
authors.forename: Akiko
authors.initials: A
authors.lastname: Ohi
authors.forename: Mikiko
authors.initials: M
authors.lastname: Ito
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kaneko
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Kido
authors.forename: Sawako
authors.initials: S
authors.lastname: Tatsumi
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Miyamoto
mesh_terms: D000818:Animals; D002453:Cell Cycle; D002478:Cells, Cultured; D053098:Familial Hypophosphatemic Rickets / Q000235:genetics; D007668:Kidney / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D009893:Opossums; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D050615:Sodium-Phosphate Cotransporter Proteins, Type IIc / Q000235:genetics / Q000502:physiology*; D014617:Vacuoles / Q000502:physiology*
chemical_list: D019269:Phosphatidylinositol 4,5-Diphosphate; D050615:Sodium-Phosphate Cotransporter Proteins, Type IIc