Down‐regulation of BMP‐4 Expression in Coronary Arterial Endothelial Cells: Role of Shear Stress and the cAMP/PKA Pathway

The role of cadherins and the cadherin-binding cytosolic protein plakoglobin in intercellular adhesion was studied in cultured human umbilical venous endothelial cells exposed to fluid shear stress. Extracellular Ca2+depletion (<10−7 M) caused the disappearance of both cadherins and plakoglobin from junctions, whereas the distribution of platelet endothelial cell adhesion molecule 1 (PECAM-1) remained unchanged. Cells stayed fully attached to each other for several hours in low Ca2+ but began to dissociate under flow conditions. At the time of recalcification, vascular endothelial (VE) cadherin and β-catenin became first visible at junctions, followed by plakoglobin with a delay of ∼20 min. Full fluid shear stress stability of the junctions correlated with the time course of the reappearance of plakoglobin. Inhibition of plakoglobin expression by microinjection of antisense oligonucleotides did not interfere with the junctional association of VE-cadherin, PECAM-1, and β-catenin. The plakoglobin-deficient cells remained fully attached to each other under resting conditions but began to dissociate in response to flow. Shear stress-induced junctional dissociation was also observed in cultures of plakoglobin-depleted arterial endothelial cells of the porcine pulmonary trunk. These observations show that interendothelial adhesion under hydrodynamic but not resting conditions requires the junctional location of cadherins associated with plakoglobin. β-Catenin cannot functionally compensate for the junctional loss of plakoglobin, and PECAM-1-mediated adhesion is not sufficient for monolayer integrity under flow.

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Shear stress stimulates nitric oxide signaling in pulmonary arterial endothelial cells via a reduction in catalase activity: role of protein kinase Cδ

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00290.2009 ◽

2010 ◽

Vol 298 (1) ◽

pp. L105-L116 ◽

Cited By ~ 27

Author(s):

Sanjiv Kumar ◽

Neetu Sud ◽

Fabio V. Fonseca ◽

Yali Hou ◽

Stephen M. Black

Keyword(s):

Nitric Oxide ◽

Endothelial Cells ◽

Shear Stress ◽

Catalase Activity ◽

Serine Phosphorylation ◽

Nitric Oxide Signaling ◽

Enos Uncoupling ◽

Pulmonary Arterial ◽

Arterial Endothelial Cells

Previous studies have indicated that acute increases in shear stress can stimulate endothelial nitric oxide synthase (eNOS) activity through increased PI3 kinase/Akt signaling and phosphorylation of Ser1177. However, the mechanism by which shear stress activates this pathway has not been adequately resolved nor has the potential role of reactive oxygen species (ROS) been evaluated. Thus, the purpose of this study was to determine if shear-mediated increases in ROS play a role in stimulating Ser1177 phosphorylation and NO signaling in pulmonary arterial endothelial cells (PAEC) exposed to acute increases in shear stress. Our initial studies demonstrated that although shear stress did not increase superoxide levels in PAEC, there was an increase in H2O2 levels. The increases in H2O2 were associated with a decrease in catalase activity but not protein levels. In addition, we found that acute shear stress caused an increase in eNOS phosphorylation at Ser1177 phosphorylation and a decrease in phosphorylation at Thr495. We also found that the overexpression of catalase significantly attenuated the shear-mediated increases in H2O2, phospho-Ser1177 eNOS, and NO generation. Further investigation identified a decrease in PKCδ activity in response to shear stress, and the overexpression of PKCδ attenuated the shear-mediated decrease in Thr495 phosphorylation and the increase in NO generation, and this led to increased eNOS uncoupling. PKCδ overexpression also attenuated Ser1177 phosphorylation through a posttranslational increase in catalase activity, mediated via a serine phosphorylation event, reducing shear-mediated increases in H2O2. Together, our data indicate that shear stress decreases PKCδ activity, altering the phosphorylation pattern catalase, leading to decreased catalase activity and increased H2O2 signaling, and this in turn leads to increases in phosphorylation of eNOS at Ser1177 and NO generation.

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H2 S-donating sildenafil (ACS6) inhibits superoxide formation and gp91phox expression in arterial endothelial cells: role of protein kinases A and G

British Journal of Pharmacology ◽

10.1038/bjp.2008.326 ◽

2008 ◽

Vol 155 (7) ◽

pp. 984-994 ◽

Cited By ~ 70

Author(s):

S Muzaffar ◽

J Y Jeremy ◽

A Sparatore ◽

P Del Soldato ◽

G D Angelini ◽

...

Keyword(s):

Endothelial Cells ◽

Protein Kinases ◽

Superoxide Formation ◽

Arterial Endothelial Cells

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EPAC1 promotes adaptive responses in human arterial endothelial cells subjected to low levels of laminar fluid shear stress: Implications in flow-related endothelial dysfunction

Cellular Signalling ◽

10.1016/j.cellsig.2016.02.016 ◽

2016 ◽

Vol 28 (6) ◽

pp. 606-619 ◽

Cited By ~ 4

Author(s):

Sarah N. Rampersad ◽

Silja I. Freitag ◽

Fabien Hubert ◽

Paulina Brzezinska ◽

Nathalie Butler ◽

...

Keyword(s):

Endothelial Cells ◽

Shear Stress ◽

Endothelial Dysfunction ◽

Fluid Shear Stress ◽

Adaptive Responses ◽

Fluid Shear ◽

Low Levels ◽

Arterial Endothelial Cells

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Shear stress augments mitochondrial ATP generation that triggers ATP release and Ca2+ signaling in vascular endothelial cells

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00204.2018 ◽

2018 ◽

Vol 315 (5) ◽

pp. H1477-H1485 ◽

Cited By ~ 15

Author(s):

Kimiko Yamamoto ◽

Hiromi Imamura ◽

Joji Ando

Keyword(s):

Endothelial Cells ◽

Shear Stress ◽

Vascular Endothelial Cells ◽

Critical Role ◽

Atp Release ◽

Vascular Endothelial ◽

The Novel ◽

Caveolin 1 ◽

Atp Generation

Vascular endothelial cells (ECs) sense and transduce hemodynamic shear stress into intracellular biochemical signals, and Ca2+ signaling plays a critical role in this mechanotransduction, i.e., ECs release ATP in the caveolae in response to shear stress and, in turn, the released ATP activates P2 purinoceptors, which results in an influx into the cells of extracellular Ca2+. However, the mechanism by which the shear stress evokes ATP release remains unclear. Here, we demonstrated that cellular mitochondria play a critical role in this process. Cultured human pulmonary artery ECs were exposed to controlled levels of shear stress in a flow-loading device, and changes in the mitochondrial ATP levels were examined by real-time imaging using a fluorescence resonance energy transfer-based ATP biosensor. Immediately upon exposure of the cells to flow, mitochondrial ATP levels increased, which was both reversible and dependent on the intensity of shear stress. Inhibitors of the mitochondrial electron transport chain and ATP synthase as well as knockdown of caveolin-1, a major structural protein of the caveolae, abolished the shear stress-induced mitochondrial ATP generation, resulting in the loss of ATP release and influx of Ca2+ into the cells. These results suggest the novel role of mitochondria in transducing shear stress into ATP generation: ATP generation leads to ATP release in the caveolae, triggering purinergic Ca2+ signaling. Thus, exposure of ECs to shear stress seems to activate mitochondrial ATP generation through caveola- or caveolin-1-mediated mechanisms. NEW & NOTEWORTHY The mechanism of how vascular endothelial cells sense shear stress generated by blood flow and transduce it into functional responses remains unclear. Real-time imaging of mitochondrial ATP demonstrated the novel role of endothelial mitochondria as mechanosignaling organelles that are able to transduce shear stress into ATP generation, triggering ATP release and purinoceptor-mediated Ca2+ signaling within the cells.

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Matrix Stiffening Induces a Pathogenic QKI-miR-7-SRSF1 Signaling Axis in Pulmonary Arterial Endothelial Cells

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00407.2020 ◽

2021 ◽

Author(s):

Chen-Shan Chen Woodcock ◽

Neha Hafeez ◽

Adam Handen ◽

Ying Tang ◽

Lloyd D Harvey ◽

...

Keyword(s):

Endothelial Cells ◽

Rna Binding ◽

Vascular Diseases ◽

Vascular Stiffness ◽

Artery Stiffness ◽

Signaling Axis ◽

Pulmonary Arterial ◽

Arterial Endothelial Cells ◽

Splicing Factor 1

Pulmonary arterial hypertension (PAH) refers to a set of heterogeneous vascular diseases defined by elevation of pulmonary arterial pressure (PAP) and pulmonary vascular resistance (PVR), leading to right ventricular (RV) remodeling and often death. Early increases in pulmonary artery stiffness in PAH drive pathogenic alterations of pulmonary arterial endothelial cells (PAECs), leading to vascular remodeling. Dysregulation of microRNAs can drive PAEC dysfunction. However, the role of vascular stiffness in regulating pathogenic microRNAs in PAH is incompletely understood. Here, we demonstrated that extracellular matrix (ECM) stiffening downregulated miR-7 levels in PAECs. The RNA binding protein Quaking (QKI) has been implicated in the biogenesis of miR-7. Correspondingly, we found that ECM stiffness up-regulated QKI, and QKI knockdown led to increased miR-7. Downstream of the QKI-miR-7 axis, the serine and arginine rich splicing factor 1 (SRSF1) was identified as a direct target of miR-7. Correspondingly, SRSF1 was reciprocally up-regulated in PAECs exposed to stiff ECM and was negatively correlated with miR-7. Decreased miR-7 and increased QKI and SRSF1 were observed in lungs from PAH patients and PAH rats exposed to SU5416/hypoxia. Lastly, miR-7 upregulation inhibited human PAEC migration, while forced SRSF1 expression reversed this phenotype, proving that miR-7 depended upon SRSF1 to control migration. In aggregate, these results define the QKI-miR-7-SRSF1 axis as a mechanosensitive mechanism linking pulmonary arterial vascular stiffness to pathogenic endothelial function. These findings emphasize implications relevant to PAH and suggest the potential benefit of developing therapies that target this miRNA-dependent axis in PAH.

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Role of TRPV4 in the Mechanotransduction of Shear Stress in Endothelial Cells

TRP Ion Channel Function in Sensory Transduction and Cellular Signaling Cascades ◽

10.1201/9781420005844-33 ◽

2006 ◽

pp. 399-410

Keyword(s):

Endothelial Cells ◽

Shear Stress

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Role of Heat Shock Protein 70 in Induction of Stress Fiber Formation in Rat Arterial Endothelial Cells in Response to Stretch Stress

ACTA HISTOCHEMICA ET CYTOCHEMICA ◽

10.1267/ahc.06011 ◽

2007 ◽

Vol 40 (1) ◽

pp. 9-17 ◽

Cited By ~ 13

Author(s):

Shan-Shun Luo ◽

Keiji Sugimoto ◽

Sachiko Fujii ◽

Tohru Takemasa ◽

Song-Bin Fu ◽

...

Keyword(s):

Endothelial Cells ◽

Heat Shock ◽

Heat Shock Protein ◽

Heat Shock Protein 70 ◽

Stress Fiber ◽

Fiber Formation ◽

Stress Fiber Formation ◽

Arterial Endothelial Cells

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The role of protein kinase C in GH secretion induced by GH-releasing factor and GH-releasing peptides in cultured ovine somatotrophs

Journal of Endocrinology ◽

10.1677/joe.0.1540219 ◽

1997 ◽

Vol 154 (2) ◽

pp. 219-230 ◽

Cited By ~ 26

Author(s):

D Wu ◽

I J Clarke ◽

C Chen

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Dependent Manner ◽

Adenylyl Cyclase Activity ◽

Down Regulation ◽

Gh Secretion ◽

Calphostin C ◽

Kinase C ◽

Pka Pathway

Abstract The involvement of protein kinase C (PKC) in the action of GH-releasing factor (GRF) and synthetic GH-releasing peptides (GHRP-2 and GHRP-6) was investigated in ovine somatotrophs in primary culture. In partially purified sheep somatotrophs, GRF and GHRP-2 caused translocation of PKC activity from the cytosol to the cell membranes and caused GH release in a dose- and time-dependent manner. GHRP-6 did not cause PKC translocation. The PKC inhibitors, calphostin C, staurosporine and chelerythrine, partially reduced GH release in response to GRF and GHRP-2 at doses which selectively inhibit PKC activity. These inhibitors totally abolished GH release caused by phorbol 12-myristate 13-acetate (PMA). Down-regulation of PKC by the treatment of cells with phorbol 12,13-dibutyrate for 16 h caused a significant (P<0·001) reduction in total PKC activity and totally abolished PKC translocation in response to a challenge with GRF, GHRP-2 or PMA. In addition, down-regulation abolished GH release in response to GRF, GHRP-2 or GHRP-6. Treatment of cells with H89, a selective PKA inhibitor, totally blocked GH release caused by either GRF or GHRP-2 and partially reduced PMA-induced GH release. H89 had no effect on PKC translocation caused by GRF, GHRP-2 or PMA and did not affect GH release caused by GHRP-6. These data suggest that GHRP-2 and GRF activate PKC in addition to stimulating adenylyl cyclase activity. Although the cAMP–protein kinase A (PKA) pathway is the major signalling pathway employed by GRF and GHRP-2, the activation of PKC may potentiate signalling via the cAMP–PKA pathway in ovine GH secretion. Importantly, the effect of PMA in increasing the secretion of GH from ovine somatotrophs is effected, in part, by up-regulation of the cAMP–PKA pathway. We conclude that there is cross-talk between the PKC pathway and the cAMP–PKA pathway in ovine somatotrophs during the action of GRF or GHRP. Journal of Endocrinology (1997) 154, 219–230

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