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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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Distribution of up- and down- regulated [Na+]i/[K+]i-sensitive genes listed in Tables 2 and 3 among major functional categories.
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pone-0110597-g005: Distribution of up- and down- regulated [Na+]i/[K+]i-sensitive genes listed in Tables 2 and 3 among major functional categories.

Mentions: Although functional characterization is somewhat artificial – because genes are usually multifunctional and fall into several categories – we ascertained that both up- and down-regulated [Na+]i/[K+]i-sensitive transcriptomes were enriched with genes involved in transcription/translation, cell adhesion, migration, proliferation, differentiation and death (Tables 1 and 2, Fig. 5). We also noted that, among [Na+]i/[K+]i-sensitive genes, the relative content of transcription/translation regulators was ∼3–4-fold higher than in total mammalian genomes [32]. Keeping this in mind, we undertook an additional search for genes encoding HIF-1, AP-1, cyclic AMP response element-binding protein (CREB), nuclear factor kappa-B (NFκB), early growth response factors (EGR), i.e. major transcription factors involved in transcriptomic changes evoked by hypoxia (for review, see [33]). Table 3 demonstrates that Na+,K+-ATPase inhibition resulted in augmented expression of genes encoding AP-1 and Egr1 and down-regulation of genes encoding regulators of the NFkB- and p53-mediated signalling pathways. We found less than 2-fold elevation of Sp1, Creb1 and Creb5 and lack of any impact of increment of the [Na+]i/]K+]i ratio on the transcription of other hypoxia-inducible transcription factors: Hif-1a, Hif-1b, Hif-2a, Hif-3a, p65, cRel, RelB, p50, p52, IκB, p53, Sp3, Gata2, Stat5, Gadd153.


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)

Distribution of up- and down- regulated [Na+]i/[K+]i-sensitive genes listed in Tables 2 and 3 among major functional categories.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0110597-g005: Distribution of up- and down- regulated [Na+]i/[K+]i-sensitive genes listed in Tables 2 and 3 among major functional categories.
Mentions: Although functional characterization is somewhat artificial – because genes are usually multifunctional and fall into several categories – we ascertained that both up- and down-regulated [Na+]i/[K+]i-sensitive transcriptomes were enriched with genes involved in transcription/translation, cell adhesion, migration, proliferation, differentiation and death (Tables 1 and 2, Fig. 5). We also noted that, among [Na+]i/[K+]i-sensitive genes, the relative content of transcription/translation regulators was ∼3–4-fold higher than in total mammalian genomes [32]. Keeping this in mind, we undertook an additional search for genes encoding HIF-1, AP-1, cyclic AMP response element-binding protein (CREB), nuclear factor kappa-B (NFκB), early growth response factors (EGR), i.e. major transcription factors involved in transcriptomic changes evoked by hypoxia (for review, see [33]). Table 3 demonstrates that Na+,K+-ATPase inhibition resulted in augmented expression of genes encoding AP-1 and Egr1 and down-regulation of genes encoding regulators of the NFkB- and p53-mediated signalling pathways. We found less than 2-fold elevation of Sp1, Creb1 and Creb5 and lack of any impact of increment of the [Na+]i/]K+]i ratio on the transcription of other hypoxia-inducible transcription factors: Hif-1a, Hif-1b, Hif-2a, Hif-3a, p65, cRel, RelB, p50, p52, IκB, p53, Sp3, Gata2, Stat5, Gadd153.

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