PKCε-CREB-Nrf2 signalling induces HO-1 in the vascular endothelium and enhances resistance to inflammation and apoptosis

• Published in: Cardiovascular research Vol. 106; no. 3; pp. 509 - 519
• Main Authors: Mylroie, Hayley, Dumont, Odile, Bauer, Andrea, Thornton, Clare C, Mackey, John, Calay, Damien, Hamdulay, Shahir S, Choo, Joan R, Boyle, Joseph J, Samarel, Allen M, Randi, Anna M, Evans, Paul C, Mason, Justin C
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01-06-2015
• Subjects: Angiotensin II - pharmacology; Animals; Apoptosis - drug effects; Cells, Cultured; Cyclic AMP Response Element-Binding Protein - genetics; Cyclic AMP Response Element-Binding Protein - metabolism; Endothelial Cells - drug effects; Endothelial Cells - enzymology; Endothelial Cells - pathology; Enzyme Activation; Enzyme Induction; Enzyme Inhibitors - pharmacology; Gene Expression Regulation; Heme Oxygenase-1 - antagonists & inhibitors; Heme Oxygenase-1 - biosynthesis; Heme Oxygenase-1 - genetics; Human Umbilical Vein Endothelial Cells - drug effects; Human Umbilical Vein Endothelial Cells - enzymology; Human Umbilical Vein Endothelial Cells - pathology; Humans; Inflammation - enzymology; Inflammation - genetics; Inflammation - pathology; Inflammation - prevention & control; Membrane Proteins - antagonists & inhibitors; Membrane Proteins - biosynthesis; Membrane Proteins - genetics; Mice, Inbred C57BL; Mice, Knockout; NF-E2-Related Factor 2 - genetics; NF-E2-Related Factor 2 - metabolism; Original; Phosphorylation; Protein Kinase C-epsilon - genetics; Protein Kinase C-epsilon - metabolism; Protoporphyrins - pharmacology; RNA Interference; Signal Transduction - drug effects; Time Factors; Transcription, Genetic; Transfection; Inflammation; Protein kinase C epsilon; Apoptosis; Endothelium; Haem oxygenase-1
• ISSN: 0008-6363; 1755-3245
• DOI: 10.1093/cvr/cvv131

Vascular injury leading to endothelial dysfunction is a characteristic feature of chronic renal disease, diabetes mellitus, and systemic inflammatory conditions, and predisposes to apoptosis and atherogenesis. Thus, endothelial dysfunction represents a potential therapeutic target for atherosclerosis prevention. The observation that activity of either protein kinase C epsilon (PKCε) or haem oxygenase-1 (HO-1) enhances endothelial cell (EC) resistance to inflammation and apoptosis led us to test the hypothesis that HO-1 is a downstream target of PKCε.
Expression of constitutively active PKCε in human EC significantly increased HO-1 mRNA and protein, whereas conversely aortas or cardiac EC from PKCε-deficient mice exhibited reduced HO-1 when compared with wild-type littermates. Angiotensin II activated PKCε and induced HO-1 via a PKCε-dependent pathway. PKCε activation significantly attenuated TNFα-induced intercellular adhesion molecule-1, and increased resistance to serum starvation-induced apoptosis. These responses were reversed by the HO antagonist zinc protoporphyrin IX. Phosphokinase antibody array analysis identified CREB1((Ser133)) phosphorylation as a PKCε signalling intermediary, and cAMP response element-binding protein 1 (CREB1) siRNA abrogated PKCε-induced HO-1 up-regulation. Likewise, nuclear factor (erythroid-derived 2)-like 2 (Nrf2) was identified as a PKCε target using nuclear translocation and DNA-binding assays, and Nrf2 siRNA prevented PKCε-mediated HO-1 induction. Moreover, depletion of CREB1 inhibited PKCε-induced Nrf2 DNA binding, suggestive of transcriptional co-operation between CREB1 and Nrf2.
PKCε activity in the vascular endothelium regulates HO-1 via a pathway requiring CREB1 and Nrf2. Given the potent protective actions of HO-1, we propose that this mechanism is an important contributor to the emerging role of PKCε in the maintenance of endothelial homeostasis and resistance to injury.