Up-regulation of megakaryocytic Na<sup>+</sup>/Ca<sup>2+</sup> exchange in klotho-deficient mice

Evi Schmid, Jing Yan, Zohreh Hosseinzadeh, Ahmad Almilaji, Ekaterina Shumilina, Makoto Kuro-O, Oliver Borst, Meinrad Gawaz, Florian Lang

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The active form of vitamin D, 1,25(OH)<inf>2</inf>D<inf>3</inf>, is a powerful regulator of cytosolic Ca<sup>2+</sup>-concentration ([Ca<sup>2+</sup>]<inf>i</inf>) in a variety of cell types. The formation of 1,25(OH)<inf>2</inf>D<inf>3</inf> is inhibited by FGF23, an effect requiring presence of klotho. 1,25(OH)<inf>2</inf>D<inf>3</inf> plasma levels are excessive in klotho-deficient mice (kl/kl). A previous study revealed that klotho-deficiency is followed by decreased activation of platelets, an effect at least in part due to blunted store operated Ca<sup>2+</sup> entry (SOCE). In other cell types 1,25(OH)<inf>2</inf>D<inf>3</inf> has been shown to up-regulate the Na<sup>+</sup>/Ca<sup>2+</sup>-exchanger, which could, depending on cell membrane potential and cytosolic Na<sup>+</sup> concentration, either decrease or increase [Ca<sup>2+</sup>]<inf>i</inf>. The present study explored whether Na<sup>+</sup>/Ca<sup>2+</sup>-exchanger activity is different in megakaryocytes isolated from kl/kl mice than in megakaryocytes isolated from wild type mice. Na<sup>+</sup>/Ca<sup>2+</sup>-exchanger induced currents were determined by whole cell patch clamp and the Na<sup>+</sup>/Ca<sup>2+</sup>-exchanger induced alterations of [Ca<sup>2+</sup>]<inf>i</inf> by Fura-2 fluorescence. As a result, the inward current and the increase of [Ca<sup>2+</sup>]<inf>i</inf> following replacement of extracellular Na<sup>+</sup> by NMDG were higher in kl/kl megakaryocytes than in wild type megakaryocytes, a difference abrogated by treatment of the mice with low Vitamin D diet. Pretreatment of wild type megakaryocytes with 1,25(OH)<inf>2</inf>D<inf>3</inf> (100 nM, 48 h) was followed by enhancement of both, inward current and increase of [Ca<sup>2+</sup>]<inf>i</inf> following replacement of extracellular Na<sup>+</sup> by NMDG. In conclusion, the present observations reveal a powerful stimulating effect of 1,25(OH)<inf>2</inf>D<inf>3</inf> on Na<sup>+</sup>/Ca<sup>2+</sup>-exchanger activity in megakaryocytes.

Original languageEnglish (US)
Pages (from-to)177-182
Number of pages6
JournalBiochemical and Biophysical Research Communications
Volume460
Issue number2
DOIs
StatePublished - May 1 2015

Fingerprint

Megakaryocytes
Vitamin D
Up-Regulation
Fura-2
Induced currents
Clamping devices
Cell membranes
Nutrition
Platelets
Fluorescence
Chemical activation
Plasmas
Platelet Activation
Membrane Potentials
Cell Membrane
Diet

Keywords

  • Cytosolic Ca<sup>2+</sup>
  • Megakaryocytes
  • Patch clamp
  • Platelets

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Cell Biology
  • Molecular Biology
  • Medicine(all)

Cite this

Up-regulation of megakaryocytic Na<sup>+</sup>/Ca<sup>2+</sup> exchange in klotho-deficient mice. / Schmid, Evi; Yan, Jing; Hosseinzadeh, Zohreh; Almilaji, Ahmad; Shumilina, Ekaterina; Kuro-O, Makoto; Borst, Oliver; Gawaz, Meinrad; Lang, Florian.

In: Biochemical and Biophysical Research Communications, Vol. 460, No. 2, 01.05.2015, p. 177-182.

Research output: Contribution to journalArticle

Schmid, E, Yan, J, Hosseinzadeh, Z, Almilaji, A, Shumilina, E, Kuro-O, M, Borst, O, Gawaz, M & Lang, F 2015, 'Up-regulation of megakaryocytic Na<sup>+</sup>/Ca<sup>2+</sup> exchange in klotho-deficient mice', Biochemical and Biophysical Research Communications, vol. 460, no. 2, pp. 177-182. https://doi.org/10.1016/j.bbrc.2015.03.002
Schmid, Evi ; Yan, Jing ; Hosseinzadeh, Zohreh ; Almilaji, Ahmad ; Shumilina, Ekaterina ; Kuro-O, Makoto ; Borst, Oliver ; Gawaz, Meinrad ; Lang, Florian. / Up-regulation of megakaryocytic Na<sup>+</sup>/Ca<sup>2+</sup> exchange in klotho-deficient mice. In: Biochemical and Biophysical Research Communications. 2015 ; Vol. 460, No. 2. pp. 177-182.
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abstract = "The active form of vitamin D, 1,25(OH)2D3, is a powerful regulator of cytosolic Ca2+-concentration ([Ca2+]i) in a variety of cell types. The formation of 1,25(OH)2D3 is inhibited by FGF23, an effect requiring presence of klotho. 1,25(OH)2D3 plasma levels are excessive in klotho-deficient mice (kl/kl). A previous study revealed that klotho-deficiency is followed by decreased activation of platelets, an effect at least in part due to blunted store operated Ca2+ entry (SOCE). In other cell types 1,25(OH)2D3 has been shown to up-regulate the Na+/Ca2+-exchanger, which could, depending on cell membrane potential and cytosolic Na+ concentration, either decrease or increase [Ca2+]i. The present study explored whether Na+/Ca2+-exchanger activity is different in megakaryocytes isolated from kl/kl mice than in megakaryocytes isolated from wild type mice. Na+/Ca2+-exchanger induced currents were determined by whole cell patch clamp and the Na+/Ca2+-exchanger induced alterations of [Ca2+]i by Fura-2 fluorescence. As a result, the inward current and the increase of [Ca2+]i following replacement of extracellular Na+ by NMDG were higher in kl/kl megakaryocytes than in wild type megakaryocytes, a difference abrogated by treatment of the mice with low Vitamin D diet. Pretreatment of wild type megakaryocytes with 1,25(OH)2D3 (100 nM, 48 h) was followed by enhancement of both, inward current and increase of [Ca2+]i following replacement of extracellular Na+ by NMDG. In conclusion, the present observations reveal a powerful stimulating effect of 1,25(OH)2D3 on Na+/Ca2+-exchanger activity in megakaryocytes.",
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AU - Hosseinzadeh, Zohreh

AU - Almilaji, Ahmad

AU - Shumilina, Ekaterina

AU - Kuro-O, Makoto

AU - Borst, Oliver

AU - Gawaz, Meinrad

AU - Lang, Florian

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AB - The active form of vitamin D, 1,25(OH)2D3, is a powerful regulator of cytosolic Ca2+-concentration ([Ca2+]i) in a variety of cell types. The formation of 1,25(OH)2D3 is inhibited by FGF23, an effect requiring presence of klotho. 1,25(OH)2D3 plasma levels are excessive in klotho-deficient mice (kl/kl). A previous study revealed that klotho-deficiency is followed by decreased activation of platelets, an effect at least in part due to blunted store operated Ca2+ entry (SOCE). In other cell types 1,25(OH)2D3 has been shown to up-regulate the Na+/Ca2+-exchanger, which could, depending on cell membrane potential and cytosolic Na+ concentration, either decrease or increase [Ca2+]i. The present study explored whether Na+/Ca2+-exchanger activity is different in megakaryocytes isolated from kl/kl mice than in megakaryocytes isolated from wild type mice. Na+/Ca2+-exchanger induced currents were determined by whole cell patch clamp and the Na+/Ca2+-exchanger induced alterations of [Ca2+]i by Fura-2 fluorescence. As a result, the inward current and the increase of [Ca2+]i following replacement of extracellular Na+ by NMDG were higher in kl/kl megakaryocytes than in wild type megakaryocytes, a difference abrogated by treatment of the mice with low Vitamin D diet. Pretreatment of wild type megakaryocytes with 1,25(OH)2D3 (100 nM, 48 h) was followed by enhancement of both, inward current and increase of [Ca2+]i following replacement of extracellular Na+ by NMDG. In conclusion, the present observations reveal a powerful stimulating effect of 1,25(OH)2D3 on Na+/Ca2+-exchanger activity in megakaryocytes.

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