ナトリウム依存性リン酸トランスポーターⅡa型（NaPi-IIa）の副甲状腺ホルモン（PTH）による調節機構

概要

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Parathyroid hormone（PTH）is the most potent and important regulator of the type Ⅱasodium-dependent phosphate transporter（NaPi-Ⅱa）, which plays a key role in renal phosphatereabsorption and maintaining inorganic phosphate homeostasis. PTH inhibits theNaPi-Ⅱa activity by stimulation of translocation from the apical plasma membrane to theintracellular organelle. In this paper, we investigated the mechanism of the translo-cationof NaPi-Ⅱa from the apical plasma membrane by cell fractionation analysis using OK-N２cells that stably express human NaPi-Ⅱa established from opossum kidney cells（OK-Pcells）. NaPi-Ⅱa was mostly localized in the caveolae-like membrane domains of the plasmamembrane in OK-N２ cells We also clarified that PTH activated both PKA and PKC, andthese kinases markedly increased the phosphorylation of their８０kDa and２５０kDa substrateson the caveolae-like membrane domains ; we identified ezrin as a candidate protein for the８０kDa substrate. We conclude that caveolae-like membrane domains play an importantrole in the targeting, translocation, and signal compartmentalization for the translocationalregulation of NaPi-Ⅱa in renal proximal tubular cells.
徳島医学会の論文
2004-12-20