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Microparticle-Induced Activation of the Vascular Endothelium Requires Caveolin-1/Caveolae.

ABSTRACT: Microparticles (MPs) are small membrane fragments shed from normal as well as activated, apoptotic or injured cells. Emerging evidence implicates MPs as a causal and/or contributing factor in altering normal vascular cell phenotype through initiation of proinflammatory signal transduction events and paracrine delivery of proteins, mRNA and miRNA. However, little is known regarding the mechanism by which MPs influence these events. Caveolae are important membrane microdomains that function as centers of signal transduction and endocytosis. Here, we tested the concept that the MP-induced pro-inflammatory phenotype shift in endothelial cells (ECs) depends on caveolae. Consistent with previous reports, MP challenge activated ECs as evidenced by upregulation of intracellular adhesion molecule-1 (ICAM-1) expression. ICAM-1 upregulation was mediated by activation of NF-?B, Poly [ADP-ribose] polymerase 1 (PARP-1) and the epidermal growth factor receptor (EGFR). This response was absent in ECs lacking caveolin-1/caveolae. To test whether caveolae-mediated endocytosis, a dynamin-2 dependent process, is a feature of the proinflammatory response, EC's were pretreated with the dynamin-2 inhibitor dynasore. Similar to observations in cells lacking caveolin-1, inhibition of endocytosis significantly attenuated MPs effects including, EGFR phosphorylation, activation of NF-?B and upregulation of ICAM-1 expression. Thus, our results indicate that caveolae play a role in mediating the pro-inflammatory signaling pathways which lead to EC activation in response to MPs.

SUBMITTER: Andrews AM

PROVIDER: S-EPMC4758735 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Microparticle-Induced Activation of the Vascular Endothelium Requires Caveolin-1/Caveolae.

Andrews Allison M AM Rizzo Victor V

PloS one 20160218 2

Microparticles (MPs) are small membrane fragments shed from normal as well as activated, apoptotic or injured cells. Emerging evidence implicates MPs as a causal and/or contributing factor in altering normal vascular cell phenotype through initiation of proinflammatory signal transduction events and paracrine delivery of proteins, mRNA and miRNA. However, little is known regarding the mechanism by which MPs influence these events. Caveolae are important membrane microdomains that function as cen ...[more]

PMID: 26891050

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Project description:RATIONALE:Anti-inflammatory and vascular protective actions of adiponectin are well recognized. However, many fundamental questions remain unanswered. OBJECTIVE:The current study attempted to identify the adiponectin receptor subtype responsible for adiponectin's vascular protective action and investigate the role of ceramidase activation in adiponectin anti-inflammatory signaling. METHODS AND RESULTS:Adiponectin significantly reduced tumor necrosis factor (TNF)?-induced intercellular adhesion molecule-1 expression and attenuated TNF?-induced oxidative/nitrative stress in human umbilical vein endothelial cells. These anti-inflammatory actions were virtually abolished by adiponectin receptor 1 (AdipoR1-), but not AdipoR2-, knockdown (KD). Treatment with adiponectin significantly increased neutral ceramidase (nCDase) activity (3.7-fold; P<0.01). AdipoR1-KD markedly reduced globular adiponectin-induced nCDase activation, whereas AdipoR2-KD only slightly reduced. More importantly, small interfering RNA-mediated nCDase-KD markedly blocked the effect of adiponectin on TNF?-induced intercellular adhesion molecule-1 expression. AMP-activated protein kinase-KD failed to block adiponectin-induced nCDase activation and modestly inhibited adiponectin anti-inflammatory effect. In contrast, in caveolin-1 KD (Cav1-KD) cells, >87% of adiponectin-induced nCDase activation was lost. Whereas adiponectin treatment failed to inhibit TNF?-induced intercellular adhesion molecule-1 expression, treatment with sphingosine-1-phosphate or SEW (sphingosine-1-phosphate receptor agonist) remained effective in Cav1-KD cells. AdipoR1 and Cav1 colocalized and coprecipitated in human umbilical vein endothelial cells. Adiponectin treatment did not affect this interaction. There is weak basal Cav1/nCDase interaction, which significantly increased after adiponectin treatment. Knockout of AdipoR1 or Cav1 abolished the inhibitory effect of adiponectin on leukocyte rolling and adhesion in vivo. CONCLUSIONS:These results demonstrate for the first time that adiponectin inhibits TNF?-induced inflammatory response via Cav1-mediated ceramidase recruitment and activation in an AdipoR1-dependent fashion.

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Microparticle-Induced Activation of the Vascular Endothelium Requires Caveolin-1/Caveolae.

Publications

Microparticle-Induced Activation of the Vascular Endothelium Requires Caveolin-1/Caveolae.

Similar Datasets

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