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: Yuji Shiozaki, Hiroko Segawa, Saori Ohnishi, Akiko Ohi, Mikiko Ito, Ichiro Kaneko, Shinsuke Kido, Sawako Tatsumi, Ken-ichi Miyamoto
• Journal: The journal of medical investigation : JMI (J Med Invest) Vol. 62 Issue 3-4 Pg. 209-18 ( 2015) ISSN: 1349-6867 [Electronic] Japan
• PMID: 26399350 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Phosphatidylinositol 4,5-Diphosphate
• Sodium-Phosphate Cotransporter Proteins, Type IIc

Topics

• Animals
• Cell Cycle
• Cells, Cultured
• Familial Hypophosphatemic Rickets (genetics)
• Kidney (metabolism, ultrastructure)
• Male
• Mice
• Mice, Inbred C57BL
• Mutation
• Opossums
• Phosphatidylinositol 4,5-Diphosphate (metabolism)
• Sodium-Phosphate Cotransporter Proteins, Type IIc (genetics, physiology)
• Vacuoles (physiology)