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Abstracts
TRANSCRIPTOMIC CHANGES IN CA2+-DEPLETED CELLS: A MAJOR ROLE OF ELEVATED INTRACELLULAR [NA+]i/[K+]i RATIO
Koltsova, S.V.1' 2, Kotelevtsev, S.V.2, Tremblay, J.1, Hamet, P.1, and Orlov, S.N.1-3
1 Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, PQ, Canada
2 Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russian Federation
3 Institute of General Pathology and Pathophysiology, Russian Academy of Medical Sciences, Moscow, Russian Federation
It is generally accepted that cell volume alteration affects transcriptome via elevation of ionic strength, i.e. total intracellular concentrations of Na+, K+ and Cl-, that, in turn, activates tonicity enhancer binding protein (TonEBP) via elevation of intracellular Ca2+ ([Ca2+]0. To examine the role of Ca2+i-mediated signaling, we studied the action of Ca2+-deletion triggered by addition of extra (EGTA) and intracellular (BAPTA) Ca2+ chelators on gene expression in vascular smooth muscle cells (VSMC) from rat aorta. In 3-hr Ca2+-deletion and Na+,K+-ATPase inhibition in K+-free medium altered expression of 4610 and 3677 transcripts, respectively. Among them we found 1844 genes whose expression was affected by both stimul thus suggesting a key role of elevated [Na+]j/[K+]j ratio. Indeed, Ca2+-depletion resulted in elevation of [Na+]i and attenuation of [K+] by ~3- and 12-fold, respectively. This effect was caused by 3-fold elevation of the permeability of the plasma membrane for Na+ and K+ documented by
increments of the rate of 22Na and 86Rb influx measured in the presence of ouabain and bumetanide. Among Na+j/K+r sensitive genes whose expression was also affected by Ca2+ depletion by more than 4-fold we found activating transcription factor Atf3, early growth response Egr1, Egr2 and Egr3, regulator of G-protein signaling Rgs2, nuclear receptor subfamily 4 group A Nr4a2 and Nr4a3, inositol 1,4,5-trophosphate 3-kinase Itpkc. Both elevation of the [Na+]i/[K+]i ratio and augmented the expression of the above listed genes triggered by Ca2+-deletion or Na+,K+-ATPase inhibition were abolished in low-Na+, high K+-medium. Thus, we report here for the first time that elevation of the [Na+]/[K+] ratio plays a key role in transcriptomic changes triggered by Ca2+ depletion. There results have profound implications for the analysis of data obtained in cells subjected to sustained cell volume modulation in the presence of polyvalent cation chelators.
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Бюллетень сибирской медицины, 2013, том 12, № 4, с. 24-68
