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Heterogeneity in apoptotic responses of microvascular endothelial cells to oxidative stress.

ABSTRACT: Oxidative stress contributes to disease and can alter endothelial cell (EC) function. EC from different vascular beds are heterogeneous in structure and function, thus we assessed the apoptotic responses of EC from lung and heart to oxidative stress. Since protein kinase C? (PKC?) is activated by oxidative stress and is an important modulator of apoptosis, experiments assessed the level of apoptosis in fixed lung and heart sections of PKC? wild-type (PKC?(+/+)) and null (PKC?(-/-)) mice housed under normoxia (21% O(2)) or hyperoxia (~95% O(2)). We noted a significantly greater number of TUNEL-positive cells in lungs of hyperoxic PKC?(+/+) mice, compared to matched hearts or normoxic organs. We found that 33% of apoptotic cells identified in hyperoxic lungs of PKC?(+/+) mice were EC, compared to 7% EC in hyperoxic hearts. We further noted that EC apoptosis was significantly reduced in lungs of PKC?(-/-) hyperoxic mice, compared to lungs of PKC?(+/+) hyperoxic mice. In vitro, both hyperoxia and H(2)O(2) promoted apoptosis in EC isolated from microvasculature of lung (LMVEC), but not from the heart (HMVEC). H(2)O(2) treatment significantly increased p38 activity in LMVEC, but not in HMVEC. Inhibition of p38 attenuated H(2)O(2)-induced LMVEC apoptosis. Baseline expression of total PKC? protein, as well as the caspase-mediated, catalytically active PKC? cleavage fragment, was higher in LMVEC, compared to HMVEC. PKC? inhibition significantly attenuated H(2)O(2)-induced LMVEC p38 activation. Conversely, overexpression of wild-type PKC? or the catalytically active PKC? cleavage product greatly increased H(2)O(2)-induced HMVEC caspase and p38 activation. We propose that enhanced susceptibility of lung EC to oxidant-induced apoptosis is due to increased PKC??p38 signaling, and we describe a PKC?-centric pathway which dictates the differential response of EC from distinct vascular beds to oxidative stress.

SUBMITTER: Grinnell K

PROVIDER: S-EPMC3533229 | biostudies-literature | 2012 May

REPOSITORIES: biostudies-literature

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Heterogeneity in apoptotic responses of microvascular endothelial cells to oxidative stress.

Grinnell Katie K Duong Huetran H Newton Julie J Rounds Sharon S Choudhary Gaurav G Harrington Elizabeth O EO

Journal of cellular physiology 20120501 5

Oxidative stress contributes to disease and can alter endothelial cell (EC) function. EC from different vascular beds are heterogeneous in structure and function, thus we assessed the apoptotic responses of EC from lung and heart to oxidative stress. Since protein kinase Cδ (PKCδ) is activated by oxidative stress and is an important modulator of apoptosis, experiments assessed the level of apoptosis in fixed lung and heart sections of PKCδ wild-type (PKCδ(+/+)) and null (PKCδ(-/-)) mice housed u ...[more]

PMID: 21732361

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Project description:RATIONALE:In rodent models of depression, oxidative stress-induced reductions in NO bioavailability contribute to impaired endothelium-dependent dilation. Endothelial dysfunction is evident in major depressive disorder (MDD); however, the molecular mediators remain undefined. OBJECTIVE:We sought to translate preclinical findings to humans by testing the role of oxidative stress in mediating microvascular endothelial dysfunction, including potential modulatory influences of sex, in MDD. METHODS AND RESULTS:Twenty-four treatment-naive, otherwise healthy, young adults with MDD (14 women; 18-23 years) and 20 healthy adults (10 women; 19-30 years) participated. Red blood cell flux (laser Doppler flowmetry) was measured during graded intradermal microdialysis perfusion of the endothelium-dependent agonist acetylcholine, alone and in combination with an NO synthase inhibitor (L-NAME), a superoxide scavenger (Tempol), and an NADPH oxidase inhibitor (apocynin), as well as during perfusion of the endothelium-independent agonist sodium nitroprusside. Tissue oxidative stress markers (eg, nitrotyrosine abundance, superoxide production) were also quantified. Endothelium-dependent dilation was blunted in MDD and mediated by reductions in NO-dependent dilation. Endothelium-independent dilation was likewise attenuated in MDD. In MDD, there were no sex differences in either NO-mediated endothelium-dependent dilation or endothelium-independent dilation. Acute scavenging of superoxide or inhibition of NADPH oxidase improved NO-dependent dilation in MDD. Expression and activity of oxidative stress markers were increased in MDD. In a subset of adults with MDD treated with a selective serotonin reuptake inhibitor for their depressive symptoms and in remission (n=8; 7 women; 19-37 years), NO-mediated endothelium-dependent dilation was preserved, but endothelium-independent dilation was impaired, compared with healthy adults. CONCLUSIONS:Oxidative stress-induced reductions in NO-dependent dilation, as well as alterations in vascular smooth muscle function, directly contribute to microvascular dysfunction in MDD. Strategies targeting vascular oxidative stress may be viable therapeutic options for improving NO-mediated endothelial function and reducing cardiovascular risk in MDD.

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Heterogeneity in apoptotic responses of microvascular endothelial cells to oxidative stress.

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Heterogeneity in apoptotic responses of microvascular endothelial cells to oxidative stress.

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