Insulin Modulates the Na+/Mg2+ Exchanger SLC41A1 and Influences Mg2+ Efflux from Intracellular Stores in Transgenic HEK293 Cells  

Oleh:

Mastrototaro, Lucia ; Tietjen, Uwe ; Sponder, Gerhard ; Vormann, Jurgen ; Aschenbach, Jorg R. ; Kolisek, Martin

Jenis: Article from Journal - ilmiah internasional
Dalam koleksi: JN: The Journal of Nutrition vol. 145 no. 11 (Nov. 2015), page 2440-2447.
Topik: Magnesium; Na+/Mg2+ Exchanger; Mg2+ Efflux; Insulin; Diabetes; Signaling; Mitochondria

Ketersediaan

Perpustakaan FK Nomor Panggil: J42.K Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada

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Isi artikel

Background: Magnesium deficiency is a common complication of diabetes with an unclear molecular background. Objective: We investigated the effect of the insulin (INS)-signaling pathway (ISP) on the regulation of Mg2+ efflux (Mg2+E) conducted by solute carrier family 41, member A1 (SLC41A1; activated by protein kinase A) in transgenic human embryonic kidney (HEK) 293 cells. Methods: HEK293 cells overexpressing SLC41A1 were loaded with the Mg2+fluorescent indicator mag-fura-2 and Mg2+. Measurements of Mg2+E were conducted in Mg2+-free buffer by using fast-filter fluorescence spectrometry. We examined the effects of INS, inhibitors of ISP or p38 mitogen-activated protein kinase (p38 MAPK), an activator of adenylate cyclase (ADC), and their combinations on SLC41A1-attributed Mg2+E. Results: The application of 400 µU/mL INS inhibited SLC41A1-mediated Mg2+E by up to 50.6% compared with INS-untreated cells (P < 0.001). Moreover, INS evoked the early onset of Mg2+ release from intracellular stores. The application of 0.1 µM wortmannin or 10 µM zardaverine (both ISP inhibitors) restored SLC41A1 Mg2+E capacity in the presence of INS to the same levels in INS-untreated cells. The simultaneous application of 10 µM forskolin, an ADC activator, and INS resulted in a reduction of Mg2+E of up to 59% compared with untreated cells (P < 0.001), which was comparable to that in cells treated with INS alone. Inhibition of p38 MAPK with 10 µM SB 202190 (SB) in the absence of INS resulted in a decrease (P < 0.001) of SLC41A1-dependent Mg2+E (by up to 49%) compared with Mg2+E measured in untreated cells. Simultaneous exposure of cells to SB and INS had a stronger inhibitory effect on SLC41A1 activity than INS alone (P < 0.05). Conclusions: INS affects intracellular Mg2+ concentration in transgenic HEK293 cells by regulating SLC41A1 activity (via ISP) and by influencing the compartmentalization and cellular distribution of Mg2+. In addition, p38 MAPK activates SLC41A1 independently of INS action.

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