Article

Early activation of the p42/p44MAPK pathway mediates adenosine-induced nitric oxide production in human endothelial cells: a novel calcium-insensitive mechanism.

Centre for Cardiovascular Biology and Medicine, GKT School of Biomedical Sciences, King's College London, Guy's Campus, London SE1 1UL, UK.
The FASEB Journal (Impact Factor: 5.48). 11/2002; 16(12):1584-94. DOI: 10.1096/fj.01-0125com
Source: PubMed

ABSTRACT Adenosine is released from the myocardium, endothelial cells, and skeletal muscle in ischemia and is an important regulator of coronary blood flow. We have already shown that acute (2 min) activation of A2a purinoceptors stimulates NO production in human fetal umbilical vein endothelial cells (1) and now report a key role for p42/p44 mitogen-activated protein kinases (p42/p44MAPK) in the regulation of the l-arginine-nitric oxide (NO) signaling pathway. Expression of mRNA for the A2a-, A2b-, and A3-adenosine receptor subtypes was abundant whereas A1-adenosine receptor mRNA levels were negligible. Activation of A2a purinoceptors by adenosine (10 microM) or the A2a receptor agonist CGS21680 (100 nM) resulted in an increase in l-arginine transport and NO release that was not mediated by changes in intracellular Ca2+, pH, or cAMP. Stimulation of endothelial cells with adenosine was associated with a membrane hyperpolarization and phosphorylation of p42/p44MAPK. l-NAME abolished the adenosine-induced hyperpolarization and stimulation of l-arginine transport whereas sodium nitroprusside activated an outward potassium current. Genistein (10 microM) and PD98059 (10 microM), an inhibitor of MAPK kinase 1/2 (MEK1/2), inhibited adenosine-stimulated l-arginine transport, NO production, and phosphorylation of p42/p44MAPK. We found no evidence for activation of eNOS via the serine/threonine kinase Akt/PKB (protein kinase B) in adenosine-stimulated cells. Our results provide the first evidence that adenosine stimulates the endothelial cell l-arginine-NO pathway in a Ca2+-insensitive manner involving p42/p44MAPK, with release of NO leading to a membrane hyperpolarization and activation of l-arginine transport.

Full-text

Available from: Giovanni E Mann, Apr 23, 2015
0 Followers
 · 
84 Views
  • Hypertension 03/2014; 63(6). DOI:10.1161/HYPERTENSIONAHA.114.03240 · 7.63 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Preeclampsia is a pregnancy-specific syndrome, defined by such clinical hallmarks as the onset of maternal hypertension and proteinuria after 20 weeks of gestation. The syndrome is also characterized by impaired blood flow through the utero-placental circulation and relative placental ischemia, which in turn, may generate feto-placental endothelial dysfunction. Endothelial dysfunction in offspring born from preeclamptic pregnancies has been associated with an increased risk of cardiovascular disease, including hypertension, later in life. Interestingly, diminished endothelial function, manifested by low angiogenic capacity, leads to hypertension in animal studies. Recently, we have shown that the adenosine receptor A2A/nitric oxide/vascular endothelial growth factor axis is reduced in human umbilical vein endothelial cells derived from preeclamptic pregnancies, an effect correlated with gestational age at onset of preeclampsia. We and others suggested that impaired vascular function might be associated with high cardiovascular risk in offspring exposed to pregnancy diseases. However, we are not aware of any studies that examine impaired adenosine-mediated angiogenesis as a possible link to hypertension in offspring born from preeclamptic pregnancies. In this review, we present evidence supporting the hypothesis that reduced adenosine-mediated angiogenesis during preeclamptic pregnancies might be associated with development of hypertension in the offspring.
    Frontiers in Pharmacology 06/2014; 5:134. DOI:10.3389/fphar.2014.00134
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To investigate the functionality of A2B adenosine receptor (A2BAR) and the nitric oxide (NO) and vascular endothelial growth factor (VEGF) signaling pathway in the endothelial cell proliferation/migration during preeclampsia, we used human umbilical vein endothelial cells (HUVECs) isolated from normal pregnancies (n = 15) or pregnancies with preeclampsia (n = 15). Experiments were performed in presence or absence of the nonselective adenosine receptor agonist NECA, the A2BAR selective antagonist MRS-1754, and the nitric oxide synthase (NOS) inhibitor L-NAME. Results indicated that cells from preeclampsia exhibited a significant higher protein level of A2BAR and logEC50 for NECA-mediated proliferation than normotensive pregnancies. The stimulatory effect of NECA (10 μ M, 24 h) on cell proliferation was prevented by MRS-1754 (5 nM) coincubation only in cells from normotensive pregnancies. Nevertheless, L-NAME (100 μ M, 24 h) reduced the NECA-induced cell proliferation/migration in HUVEC from normal pregnancy; however in preeclampsia only NECA-induced cell proliferation was reduced by L-NAME. Moreover, NECA increased protein nitration and abundance of VEGF in cells from normal pregnancy and effect prevented by MRS-1754 coincubation. Nevertheless, in preeclampsia NECA did not affect the protein level of VEGF. In conclusion HUVECs from preeclampsia exhibit elevated protein level of A2BAR and impairment of A2BAR-mediated NO/VEGF signaling pathway.
    BioMed Research International 04/2014; 2014:274507. DOI:10.1155/2014/274507 · 2.71 Impact Factor