| 20339118 |
Montezano AC, Burger D, Paravicini TM, Chignalia AZ, Yusuf H, Almasri M, He Y, Callera GE, He G, Krause KH, Lambeth D, Quinn MT, Touyz RM: Nicotinamide Adenine Dinucleotide Phosphate Reduced Oxidase 5 (Nox5) Regulation by Angiotensin II and Endothelin-1 Is Mediated via Calcium/Calmodulin-Dependent, Rac-1-Independent Pathways in Human Endothelial Cells. Circ Res. 2010 Mar 25.
Rationale: Although Nox5 (Nox2 homolog) has been identified in the vasculature, its regulation and functional significance remain unclear. Objectives: We sought to test whether vasoactive agents regulate Nox5 through Ca (2+)/calmodulin-dependent processes and whether Ca (2+)-sensitive Nox5, associated with Rac-1, generates superoxide (O2 (.-)) and activates growth and inflammatory responses via mitogen-activated protein kinases in human endothelial cells (ECs). Methods and Results: Cultured ECs, exposed to angiotensin II (Ang II) and endothelin (ET)-1 in the absence and presence of diltiazem (Ca (2+) channel blocker), calmidazolium (calmodulin inhibitor), and EHT1864 (Rac-1 inhibitor), were studied. Nox5 was downregulated with small interfering RNA. Ang II and ET-1 increased Nox5 expression (mRNA and protein). Effects were inhibited by actinomycin D and cycloheximide and blunted by diltiazem, calmidazolium and low extracellular Ca (2+) ([Ca (2+)] e). Ang II and ET-1 activated NADPH oxidase, an effect blocked by low [Ca (2+)] e, but not by EHT1864. Nox5 knockdown abrogated agonist-stimulated O2 (.-) production and inhibited phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, but not p38 MAPK (mitogen-activated protein kinase) or SAPK/JNK (stress-activated protein kinase/c-Jun N-terminal kinase). Nox5 small interfering RNA blunted Ang II-induced, but not ET-1-induced, upregulation of proliferating-cell nuclear antigen and vascular cell adhesion molecule-1, important in growth and inflammation. Conclusions: Human ECs possess functionally active Nox5, regulated by Ang II and ET-1 through Ca (2+)/calmodulin-dependent, Rac-1-independent mechanisms. Nox5 activation by Ang II and ET-1 induces ROS generation and ERK1/2 phosphorylation. Nox5 is involved in ERK1/2-regulated growth and inflammatory signaling by Ang II but not by ET-1. We elucidate novel mechanisms whereby vasoactive peptides regulate Nox5 in human ECs and demonstrate differential Nox5-mediated functional responses by Ang II and ET-1. Such phenomena link Ca (2+)/calmodulin to Nox5 signaling, potentially important in the regulation of endothelial function by Ang II and ET-1. |
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