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Distinct functional properties of two electrogenic isoforms of the SLC34 Na‐Pi cotransporter

Inorganic phosphate (P(i)) is crucial for proper cellular function in all organisms. In mammals, type II Na‐Pi cotransporters encoded by members of the Slc34 gene family play major roles in the maintenance of P(i) homeostasis. However, the molecular mechanisms regulating Na‐Pi cotransporter activity...

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Autores principales: Mizutani, Natsuki, Okochi, Yoshifumi, Okamura, Yasushi
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6656865/
https://www.ncbi.nlm.nih.gov/pubmed/31342668
http://dx.doi.org/10.14814/phy2.14156
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author Mizutani, Natsuki
Okochi, Yoshifumi
Okamura, Yasushi
author_facet Mizutani, Natsuki
Okochi, Yoshifumi
Okamura, Yasushi
author_sort Mizutani, Natsuki
collection PubMed
description Inorganic phosphate (P(i)) is crucial for proper cellular function in all organisms. In mammals, type II Na‐Pi cotransporters encoded by members of the Slc34 gene family play major roles in the maintenance of P(i) homeostasis. However, the molecular mechanisms regulating Na‐Pi cotransporter activity within the plasma membrane are largely unknown. In the present study, we used two approaches to examine the effect of changing plasma membrane phosphatidylinositol 4,5‐bisphosphate (PI(4,5)P(2)) levels on the activities of two electrogenic Na‐Pi cotransporters, NaPi‐IIa and NaPi‐IIb. To deplete plasma membrane PI(4,5)P(2) in Xenopus oocytes, we utilized Ciona intestinalis voltage‐sensing phosphatase (Ci‐VSP), which dephosphorylates PI(4,5)P(2) to phosphatidylinositol 4‐phosphate (PI(4)P). Upon activation of Ci‐VSP, NaPi‐IIb currents were significantly decreased, whereas NaPi‐IIa currents were unaffected. We also used the rapamycin‐inducible Pseudojanin (PJ) system to deplete both PI(4,5)P(2) and PI(4)P from the plasma membrane of cultured Neuro 2a cells. Depletion of PI(4,5)P(2) and PI(4)P using PJ significantly reduced NaPi‐IIb activity, but NaPi‐IIa activity was unaffected, which excluded the possibility that NaPi‐IIa is equally sensitive to PI(4,5)P(2) and PI(4)P. These results indicate that NaPi‐IIb activity is regulated by PI(4,5)P(2), whereas NaPi‐IIa is not sensitive to either PI(4,5)P(2) or PI(4)P. In addition, patch clamp recording of NaPi‐IIa and NaPi‐IIb currents in cultured mammalian cells enabled kinetic analysis with higher temporal resolution, revealing their distinct kinetic properties.
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spelling pubmed-66568652019-07-31 Distinct functional properties of two electrogenic isoforms of the SLC34 Na‐Pi cotransporter Mizutani, Natsuki Okochi, Yoshifumi Okamura, Yasushi Physiol Rep Original Research Inorganic phosphate (P(i)) is crucial for proper cellular function in all organisms. In mammals, type II Na‐Pi cotransporters encoded by members of the Slc34 gene family play major roles in the maintenance of P(i) homeostasis. However, the molecular mechanisms regulating Na‐Pi cotransporter activity within the plasma membrane are largely unknown. In the present study, we used two approaches to examine the effect of changing plasma membrane phosphatidylinositol 4,5‐bisphosphate (PI(4,5)P(2)) levels on the activities of two electrogenic Na‐Pi cotransporters, NaPi‐IIa and NaPi‐IIb. To deplete plasma membrane PI(4,5)P(2) in Xenopus oocytes, we utilized Ciona intestinalis voltage‐sensing phosphatase (Ci‐VSP), which dephosphorylates PI(4,5)P(2) to phosphatidylinositol 4‐phosphate (PI(4)P). Upon activation of Ci‐VSP, NaPi‐IIb currents were significantly decreased, whereas NaPi‐IIa currents were unaffected. We also used the rapamycin‐inducible Pseudojanin (PJ) system to deplete both PI(4,5)P(2) and PI(4)P from the plasma membrane of cultured Neuro 2a cells. Depletion of PI(4,5)P(2) and PI(4)P using PJ significantly reduced NaPi‐IIb activity, but NaPi‐IIa activity was unaffected, which excluded the possibility that NaPi‐IIa is equally sensitive to PI(4,5)P(2) and PI(4)P. These results indicate that NaPi‐IIb activity is regulated by PI(4,5)P(2), whereas NaPi‐IIa is not sensitive to either PI(4,5)P(2) or PI(4)P. In addition, patch clamp recording of NaPi‐IIa and NaPi‐IIb currents in cultured mammalian cells enabled kinetic analysis with higher temporal resolution, revealing their distinct kinetic properties. John Wiley and Sons Inc. 2019-07-24 /pmc/articles/PMC6656865/ /pubmed/31342668 http://dx.doi.org/10.14814/phy2.14156 Text en © 2019 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society. This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Research
Mizutani, Natsuki
Okochi, Yoshifumi
Okamura, Yasushi
Distinct functional properties of two electrogenic isoforms of the SLC34 Na‐Pi cotransporter
title Distinct functional properties of two electrogenic isoforms of the SLC34 Na‐Pi cotransporter
title_full Distinct functional properties of two electrogenic isoforms of the SLC34 Na‐Pi cotransporter
title_fullStr Distinct functional properties of two electrogenic isoforms of the SLC34 Na‐Pi cotransporter
title_full_unstemmed Distinct functional properties of two electrogenic isoforms of the SLC34 Na‐Pi cotransporter
title_short Distinct functional properties of two electrogenic isoforms of the SLC34 Na‐Pi cotransporter
title_sort distinct functional properties of two electrogenic isoforms of the slc34 na‐pi cotransporter
topic Original Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6656865/
https://www.ncbi.nlm.nih.gov/pubmed/31342668
http://dx.doi.org/10.14814/phy2.14156
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