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Transcriptomic changes triggered by hypoxia: evidence for HIF-1α-independent, [Na+]i/[K+]i-mediated, excitation-transcription coupling.

Koltsova SV, Shilov B, Birulina JG, Akimova OA, Haloui M, Kapilevich LV, Gusakova SV, Tremblay J, Hamet P, Orlov SN - PLoS ONE (2014)

Bottom Line: Incubation of RASMC in ischemic conditions resulted in ∼3-fold elevation of [Na+]i and 2-fold reduction of [K+]i.In ouabain-treated RASMC, low-Na+, high-K+ medium abolished amplification of the [Na+]i/[K+]i ratio as well as the increased expression of all tested genes.In cells subjected to hypoxia and glucose deprivation, dissipation of the transmembrane gradient of Na+ and K+ completely eliminated increment of Fos, Atf3, Ptgs2 and Per2 mRNAs and sharply diminished augmentation expression of Klf10, Edn1, Nr4a1 and Hes1.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Moscow State University, Moscow, Russia; Department of Medicine, Centre de recherche, Centre hospitalier de l'Université de Montréal, Montreal, Quebec, Canada.

ABSTRACT
This study examines the relative impact of canonical hypoxia-inducible factor-1alpha- (HIF-1α and Na+i/K+i-mediated signaling on transcriptomic changes evoked by hypoxia and glucose deprivation. Incubation of RASMC in ischemic conditions resulted in ∼3-fold elevation of [Na+]i and 2-fold reduction of [K+]i. Using global gene expression profiling we found that Na+,K+-ATPase inhibition by ouabain or K+-free medium in rat aortic vascular smooth muscle cells (RASMC) led to the differential expression of dozens of genes whose altered expression was previously detected in cells subjected to hypoxia and ischemia/reperfusion. For further investigations, we selected Cyp1a1, Fos, Atf3, Klf10, Ptgs2, Nr4a1, Per2 and Hes1, i.e. genes possessing the highest increments of expression under sustained Na+,K+-ATPase inhibition and whose implication in the pathogenesis of hypoxia was proved in previous studies. In ouabain-treated RASMC, low-Na+, high-K+ medium abolished amplification of the [Na+]i/[K+]i ratio as well as the increased expression of all tested genes. In cells subjected to hypoxia and glucose deprivation, dissipation of the transmembrane gradient of Na+ and K+ completely eliminated increment of Fos, Atf3, Ptgs2 and Per2 mRNAs and sharply diminished augmentation expression of Klf10, Edn1, Nr4a1 and Hes1. In contrast to low-Na+, high-K+ medium, RASMC transfection with Hif-1a siRNA attenuated increments of Vegfa, Edn1, Klf10 and Nr4a1 mRNAs triggered by hypoxia but did not impact Fos, Atf3, Ptgs2 and Per2 expression. Thus, our investigation demonstrates, for the first time, that Na+i/K+i-mediated, Hif-1α- -independent excitation-transcription coupling contributes to transcriptomic changes evoked in RASMC by hypoxia and glucose deprivation.

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Correlation analysis of transcripts whose expression is altered by ouabain and K+-free medium in RVSMC by more than by 1.2-fold with p<0.05.The total number of transcripts subjected to analysis is shown in Figure 2B. Transcript expression in control cells was taken as 1.00. The fold change was determined as log transformed treatment/control expression ratio.
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pone-0110597-g004: Correlation analysis of transcripts whose expression is altered by ouabain and K+-free medium in RVSMC by more than by 1.2-fold with p<0.05.The total number of transcripts subjected to analysis is shown in Figure 2B. Transcript expression in control cells was taken as 1.00. The fold change was determined as log transformed treatment/control expression ratio.

Mentions: Figure 3B discloses that the number of differentially-expressed transcripts in RASMC treated for 6 hr with ouabain or K+-free medium totalled 8,266 and 8,264, respectively. Further analysis determined that the expression of 6,412 transcripts was affected by both stimuli (Fig. 3B). Significantly, we observed highly significant (p<4×10−9) and positive (R2>0.80) correlations between levels of differentially-expressed transcripts identified in the presence of ouabain and K+-free medium (Fig. 4). Because the gain of [Na+]i and loss of [K+]i in cells treated with ouabain or K+-free medium are similar (Fig. 1), the results strongly suggest that the changes in gene expression evoked by both stimuli occur in response to elevation of the [Na+]i/[K+]i ratio rather than [Na+]i/[K+]i-independent events.


Transcriptomic changes triggered by hypoxia: evidence for HIF-1α-independent, [Na+]i/[K+]i-mediated, excitation-transcription coupling.

Koltsova SV, Shilov B, Birulina JG, Akimova OA, Haloui M, Kapilevich LV, Gusakova SV, Tremblay J, Hamet P, Orlov SN - PLoS ONE (2014)

Correlation analysis of transcripts whose expression is altered by ouabain and K+-free medium in RVSMC by more than by 1.2-fold with p<0.05.The total number of transcripts subjected to analysis is shown in Figure 2B. Transcript expression in control cells was taken as 1.00. The fold change was determined as log transformed treatment/control expression ratio.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4222758&req=5

pone-0110597-g004: Correlation analysis of transcripts whose expression is altered by ouabain and K+-free medium in RVSMC by more than by 1.2-fold with p<0.05.The total number of transcripts subjected to analysis is shown in Figure 2B. Transcript expression in control cells was taken as 1.00. The fold change was determined as log transformed treatment/control expression ratio.
Mentions: Figure 3B discloses that the number of differentially-expressed transcripts in RASMC treated for 6 hr with ouabain or K+-free medium totalled 8,266 and 8,264, respectively. Further analysis determined that the expression of 6,412 transcripts was affected by both stimuli (Fig. 3B). Significantly, we observed highly significant (p<4×10−9) and positive (R2>0.80) correlations between levels of differentially-expressed transcripts identified in the presence of ouabain and K+-free medium (Fig. 4). Because the gain of [Na+]i and loss of [K+]i in cells treated with ouabain or K+-free medium are similar (Fig. 1), the results strongly suggest that the changes in gene expression evoked by both stimuli occur in response to elevation of the [Na+]i/[K+]i ratio rather than [Na+]i/[K+]i-independent events.

Bottom Line: Incubation of RASMC in ischemic conditions resulted in ∼3-fold elevation of [Na+]i and 2-fold reduction of [K+]i.In ouabain-treated RASMC, low-Na+, high-K+ medium abolished amplification of the [Na+]i/[K+]i ratio as well as the increased expression of all tested genes.In cells subjected to hypoxia and glucose deprivation, dissipation of the transmembrane gradient of Na+ and K+ completely eliminated increment of Fos, Atf3, Ptgs2 and Per2 mRNAs and sharply diminished augmentation expression of Klf10, Edn1, Nr4a1 and Hes1.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Moscow State University, Moscow, Russia; Department of Medicine, Centre de recherche, Centre hospitalier de l'Université de Montréal, Montreal, Quebec, Canada.

ABSTRACT
This study examines the relative impact of canonical hypoxia-inducible factor-1alpha- (HIF-1α and Na+i/K+i-mediated signaling on transcriptomic changes evoked by hypoxia and glucose deprivation. Incubation of RASMC in ischemic conditions resulted in ∼3-fold elevation of [Na+]i and 2-fold reduction of [K+]i. Using global gene expression profiling we found that Na+,K+-ATPase inhibition by ouabain or K+-free medium in rat aortic vascular smooth muscle cells (RASMC) led to the differential expression of dozens of genes whose altered expression was previously detected in cells subjected to hypoxia and ischemia/reperfusion. For further investigations, we selected Cyp1a1, Fos, Atf3, Klf10, Ptgs2, Nr4a1, Per2 and Hes1, i.e. genes possessing the highest increments of expression under sustained Na+,K+-ATPase inhibition and whose implication in the pathogenesis of hypoxia was proved in previous studies. In ouabain-treated RASMC, low-Na+, high-K+ medium abolished amplification of the [Na+]i/[K+]i ratio as well as the increased expression of all tested genes. In cells subjected to hypoxia and glucose deprivation, dissipation of the transmembrane gradient of Na+ and K+ completely eliminated increment of Fos, Atf3, Ptgs2 and Per2 mRNAs and sharply diminished augmentation expression of Klf10, Edn1, Nr4a1 and Hes1. In contrast to low-Na+, high-K+ medium, RASMC transfection with Hif-1a siRNA attenuated increments of Vegfa, Edn1, Klf10 and Nr4a1 mRNAs triggered by hypoxia but did not impact Fos, Atf3, Ptgs2 and Per2 expression. Thus, our investigation demonstrates, for the first time, that Na+i/K+i-mediated, Hif-1α- -independent excitation-transcription coupling contributes to transcriptomic changes evoked in RASMC by hypoxia and glucose deprivation.

Show MeSH
Related in: MedlinePlus