Sustained Endothelial Nitric-oxide Synthase Activation Requires Capacitative Ca2+ Entry

Lin, Sheng‐Xiang; Fagan, Kent A.; Li, Kai Xun; Shaul, Philip W.; Cooper, Dermot M.F.; Rodman, David M.

doi:10.1074/jbc.275.24.17979

Cited by 168 publications

(130 citation statements)

References 47 publications

(42 reference statements)

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“…Ca 2+ release from intracellular stores was required for the activation of eNOS by flow and agonists in aorta [31]. Other studies have found that sustained eNOS activation in endothelial cells by agonists required capacitative Ca 2+ entry [41,42]. Our data also show that sustained eNOS activation by bradykinin is dependent on Ca 2+ entry (Fig.…”

Section: Discussionsupporting

confidence: 77%

Chronic exposure to high glucose impairs bradykinin-stimulated nitric oxide production by interfering with the phospholipase-C-implicated signalling pathway in endothelial cells: evidence for the involvement of protein kinase C

Tang

2004

Diabetologia

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Aims/hypothesis. Overwhelming evidence indicates that endothelial cell dysfunction in diabetes is characterised by diminished endothelium-dependent relaxation, but the matter of the underlying molecular mechanism remains unclear. As nitric oxide (NO) production from the endothelium is the major player in endothelium-mediated vascular relaxation, we investigated the effects of high glucose on NO production, and the possible alterations of signalling pathways implicated in this scenario. Methods. NO production and intracellular Ca 2+ levels ([Ca 2+ ] i ) were assessed using the fluorescent probes 4,5-diaminofluorescein diacetate and fura-2 respectively. Results. Exposure of cultured bovine aortic endothelial cells to high glucose for 5 or 10 days significantly reduced NO production induced by bradykinin (but not by Ca 2+ ionophore) in a time-and dose-dependent manner. This was probably due to an attenuation in bradykinin-induced elevations of [Ca 2+ ] i under these conditions, since a close correlation between [Ca 2+ ] i increases and NO generation was observed in intact bovine aortic endothelial cells. Both bradykinin-promoted intracellular Ca 2+ mobilisation and extracellular Ca 2+ entry were affected. Moreover, bradykinin-induced formation of Ins(1,4,5)P 3 , a phospholipase C product leading to increases in [Ca 2+ ] i , was also inhibited following high glucose culture. This abnormality was not attributable to a decrease in inositol phospholipids, but possibly to a reduction in the number of bradykinin receptors. The alterations in NO production, the increases in [Ca 2+ ] i , and the bradykinin receptor number due to high glucose could be largely reversed by protein kinase C inhibitors and D-α-tocopherol (antioxidant). Conclusions/interpretation. Chronic exposure to high glucose reduces NO generation in endothelial cells, probably by impairing phospholipase-C-mediated Ca 2+ signalling due to excess protein kinase C activation. This defect in NO release may contribute to the diminished endothelium-dependent relaxation and thus to the development of cardiovascular diseases in diabetes.

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Section: Discussionsupporting

confidence: 77%

Chronic exposure to high glucose impairs bradykinin-stimulated nitric oxide production by interfering with the phospholipase-C-implicated signalling pathway in endothelial cells: evidence for the involvement of protein kinase C

Tang

2004

Diabetologia

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“…This latter site piqued our interest because there was literature in the nitric oxide synthase field suggesting a role for a calmodulin-binding site in the targeting of nitric oxide synthase to caveolae (17). Furthermore, it has been shown that endothelial nitric oxide synthase is dependent on CCE for its Ca 2ϩ -dependent activity (31,32). We first established that, as with AC6, upon depletion of cellular cholesterol, the response of AC8 to CCE was much reduced.…”

Section: Discussionmentioning

confidence: 98%

Residence of Adenylyl Cyclase Type 8 in Caveolae Is Necessary but Not Sufficient for Regulation by Capacitative Ca2+Entry

Smith

Fagan

et al. 2002

Journal of Biological Chemistry

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107

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(2000) J. Biol. Chem. 275, 26530 -26537). In the present study, we established that depletion of cellular cholesterol ablated the regulation by CCE of a Ca 2؉ -stimulable adenylyl cyclase, AC8, heterologously expressed in HEK293 cells. We considered the possibility that a calmodulin-binding domain in the N terminus of AC8, which is not required for in vitro regulation by Ca 2؉ , might play a targeting role. Deletion and mutation of the N terminus did attenuate the enzyme's sensitivity to CCE without altering its in vitro responsiveness to Ca 2؉ /calmodulin. Both N terminus-deleted AC8 and wild type AC8 were expressed at the plasma membrane, as shown by imaging analysis of green fluorescence protein-tagged constructs. However, not only wild type AC8 but also the CCE-insensitive mutants occurred in caveolar fractions of the plasma membranes, even though a Ca 2؉ -insensitive adenylyl cyclase, AC7, was excluded from caveolae. Finally, the AC8 mutants were no more responsive to nonphysiological elevation of Ca 2؉ than the wild type. We conclude that (i) not all adenylyl cyclases reside in caveolae, (ii) the calmodulin-binding domain in the N terminus of AC8 does not play a role in caveolar targeting, (iii) the N terminus does play a role in associating AC8 with factors that confer sensitivity to CCE, and (iv) residence of Ca 2؉ -sensitive adenylyl cyclases in caveolae is essential but not sufficient for regulation by CCE.

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“…Therefore, eNOS, by elevating cGMP level, is a likely key upstream player in the signaling mechanism of HO-2 activation. eNOS, a Ca 2+ /calmodulindependent enzyme, is highly regulated by intracellular Ca 2+ [91,92] and, therefore, it is possible that glutamate, via iGluR-mediated Ca 2+ entry and/or protein phosphorylation, initiates eNOS-mediated cGMP-dependent signaling cascade leading to HO-2 activation.…”

Section: Glutamate Receptors In Cerebral Vascular Endothelium and Ho-mentioning

confidence: 99%

Cerebroprotective Functions of HO-2

Parfenova¹,

Leffler²

2008

CPD

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The constitutive isoform of heme oxygenase, HO-2, is highly expressed in the brain and in cerebral vessels. HO-2 functions in the brain have been evaluated using pharmacological inhibitors of the enzyme and HO-2 gene deletion in in vivo animal models and in cultured cells (neurons, astrocytes, cerebral vascular endothelial cells). Rapid activation of HO-2 via posttranslational modifications without upregulation of HO-2 expression or HO-1 induction coincides with the increase in cerebral blood flow aimed at maintaining brain homeostasis and neuronal survival during seizures, hypoxia, and hypotension. Pharmacological inhibition or gene deletion of brain HO-2 exacerbates oxidative stress induced by seizures, glutamate, and inflammatory cytokines, and causes cerebral vascular injury. Carbon monoxide (CO) and bilirubin, the end products of HO-catalyzed heme degradation, have distinct cytoprotective functions. CO, by binding to a heme prosthetic group, regulates the key components of cell signaling, including BK Ca channels, guanylyl cyclase, NADPH oxidase, and the mitochondria respiratory chain. Cerebral vasodilator effects of CO are mediated via activation of BK Ca channels and guanylyl cyclase. CO, by inhibiting the major components of endogenous oxidantgenerating machinery, NADPH oxidase and the cytochrome C oxidase of the mitochondrial respiratory chain, blocks formation of reactive oxygen species. Bilirubin, via redox cycling with biliverdin, is a potent oxidant scavenger that removes preformed oxidants. Overall, HO-2 has dual housekeeping cerebroprotective functions by maintaining autoregulation of cerebral blood flow aimed at improving neuronal survival in a changing environment, and by providing an effective defense mechanism that blocks oxidant formation and prevents cell death caused by oxidative stress. KeywordsHeme oxygenase; cerebral protection; cerebrovascular disease; oxidative stress; seizures; carbon monoxide; bilirubin Vasodilator role of CO in cerebral circulation A. Vasoactive effects of exogenous CO in cerebral vesselsExperimental studies in newborn pigs conducted using in vivo and in vitro approaches demonstrate that exogenous CO is a potent vasodilator in cerebral circulation [1][2][3][4][5][6][7]. CO can be delivered to the brain as CO gas dissolved in a physiological buffer or as recently introduced CO-releasing molecules (CO-RMs) that release CO on illumination (dimanganese decacarbonyl, DMDC) or when dissolved in physiologically buffered solutions (sodium boranocarbonate, CO-RM-A1) [8,9]. In vivo, CO, DMDC and CORM-A1 applied directly to the brain surface under the cranial window at concentrations ≥10 −7 M causes dilation of pial arterioles, major resistance brain vessels that define the cerebral blood

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Sustained Endothelial Nitric-oxide Synthase Activation Requires Capacitative Ca2+ Entry

Cited by 168 publications

References 47 publications

Chronic exposure to high glucose impairs bradykinin-stimulated nitric oxide production by interfering with the phospholipase-C-implicated signalling pathway in endothelial cells: evidence for the involvement of protein kinase C

Chronic exposure to high glucose impairs bradykinin-stimulated nitric oxide production by interfering with the phospholipase-C-implicated signalling pathway in endothelial cells: evidence for the involvement of protein kinase C

Residence of Adenylyl Cyclase Type 8 in Caveolae Is Necessary but Not Sufficient for Regulation by Capacitative Ca2+Entry

Cerebroprotective Functions of HO-2

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