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Transcriptional upregulation of ?2?-1 elevates arterial smooth muscle cell voltage-dependent Ca2+ channel surface expression and cerebrovascular constriction in genetic hypertension.

ABSTRACT: A hallmark of hypertension is an increase in arterial myocyte voltage-dependent Ca2+ (CaV1.2) currents that induces pathological vasoconstriction. CaV1.2 channels are heteromeric complexes composed of a pore-forming CaV1.2?1 with auxiliary ?2? and ? subunits. Molecular mechanisms that elevate CaV1.2 currents during hypertension and the potential contribution of CaV1.2 auxiliary subunits are unclear. Here, we investigated the pathological significance of ?2? subunits in vasoconstriction associated with hypertension. Age-dependent development of hypertension in spontaneously hypertensive rats was associated with an unequal elevation in ?2?-1 and CaV1.2?1 mRNA and protein in cerebral artery myocytes, with ?2?-1 increasing more than CaV1.2?1. Other ?2? isoforms did not emerge in hypertension. Myocytes and arteries of hypertensive spontaneously hypertensive rats displayed higher surface-localized ?2?-1 and CaV1.2?1 proteins, surface ?2?-1:CaV1.2?1 ratio, CaV1.2 current density and noninactivating current, and pressure- and depolarization-induced vasoconstriction than those of Wistar-Kyoto controls. Pregabalin, an ?2?-1 ligand, did not alter ?2?-1 or CaV1.2?1 total protein but normalized ?2?-1 and CaV1.2?1 surface expression, surface ?2?-1:CaV1.2?1, CaV1.2 current density and inactivation, and vasoconstriction in myocytes and arteries of hypertensive rats to control levels. Genetic hypertension is associated with an elevation in ?2?-1 expression that promotes surface trafficking of CaV1.2 channels in cerebral artery myocytes. This leads to an increase in CaV1.2 current-density and a reduction in current inactivation that induces vasoconstriction. Data also suggest that ?2?-1 targeting is a novel strategy that may be used to reverse pathological CaV1.2 channel trafficking to induce cerebrovascular dilation in hypertension.

SUBMITTER: Bannister JP

PROVIDER: S-EPMC3632309 | biostudies-literature | 2012 Oct

REPOSITORIES: biostudies-literature

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Transcriptional upregulation of α2δ-1 elevates arterial smooth muscle cell voltage-dependent Ca2+ channel surface expression and cerebrovascular constriction in genetic hypertension.

Bannister John P JP Bulley Simon S Narayanan Damodaran D Thomas-Gatewood Candice C Luzny Patrik P Pachuau Judith J Jaggar Jonathan H JH

Hypertension (Dallas, Tex. : 1979) 20120904 4

A hallmark of hypertension is an increase in arterial myocyte voltage-dependent Ca2+ (CaV1.2) currents that induces pathological vasoconstriction. CaV1.2 channels are heteromeric complexes composed of a pore-forming CaV1.2α1 with auxiliary α2δ and β subunits. Molecular mechanisms that elevate CaV1.2 currents during hypertension and the potential contribution of CaV1.2 auxiliary subunits are unclear. Here, we investigated the pathological significance of α2δ subunits in vasoconstriction associate ...[more]

PMID: 22949532

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Project description:Altered Ca2+ handling has both immediate physiological effects and long-term genomic effects on vascular smooth muscle function. Previously we have shown that elevation of cytoplasmic Ca2+ through voltage-dependent Ca2+ channels (VDCCs) or store-operated Ca2+ channels (SOCCs) results in phosphorylation of the Ca2+/cAMP response element binding protein (CREB) in cerebral arteries. Here we demonstrate that stimulation of these different Ca2+ influx pathways results in transcriptional activation of a distinct, yet overlapping set of genes, and that the induction of selected CRE-regulated genes is prevented by the addition of corresponding Ca2+ channel blockers. Using oligonucleotide array analysis, changes in mRNA levels were quantified following membrane depolarization with K+ or depletion of intracellular Ca2+ stores with thapsigargin in human cerebral vascular smooth muscle cells. Array results for differentially regulated genes containing a CRE were confirmed by quantitative RT-PCR, and corresponding changes in protein expression were shown by Western blot analysis and immunofluorescence. Membrane depolarization induced a transient increase in c-fos mRNA and a sustained increase in early growth response-1 (Egr-1) mRNA and protein that were inhibited by application of the VDCC blocker, nimodipine, and the SOCC inhibitor, 2-aminoethoxydiphenylborate (2-APB). Thapsigargin induced a sustained increase in c-fos mRNA and MAP kinase phosphatase-1 (MKP-1) mRNA and protein, and these effects were decreased by 2-APB but not by nimodipine. Our findings thus indicate that Ca2+ entry through VDCCs and SOCCs can differentially regulate CRE-containing genes in vascular smooth muscle and imply that signals involved in growth modulation are both temporally and spatially regulated by Ca2+. Experiment Overall Design: each of three experiments cell cultures were split three ways; one of the resulting samples was left untreated (C), another was treated with thapsigargin (TG), and the third was treated with elevated K+ (K). The resulting nine samples were used for triplicate estimates of the response of each gene to TG and K treatments. Experiment Overall Design: We tested the prospective hypothesis that genes having a CRE are differentially expressed after TG or K treatment using a permutation test: each of the 22,283 probe sets on the Affymetrix GeneChip was categorized two ways based on 1) whether or not it contains a CRE or not . Independence of CRE and threshold differential expression was rejected by Fisherâs exact test for both TG treatment ( ) and K treatment ( ). Target genes (c-fos, egr-1, and mkp-1 ) were identified based on ranking.

Dataset Information

Transcriptional upregulation of ?2?-1 elevates arterial smooth muscle cell voltage-dependent Ca2+ channel surface expression and cerebrovascular constriction in genetic hypertension.

Publications

Transcriptional upregulation of α2δ-1 elevates arterial smooth muscle cell voltage-dependent Ca2+ channel surface expression and cerebrovascular constriction in genetic hypertension.

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