title: Vascular endothelial-cadherin downregulation as a feature of endothelial transdifferentiation in monocrotaline-induced pulmonary hypertension.
abstract: Increased pulmonary vascular resistance in pulmonary hypertension (PH) is caused by vasoconstriction and obstruction of small pulmonary arteries by proliferating vascular cells. In analogy to cancer, subsets of proliferating cells may be derived from endothelial cells transitioning into a mesenchymal phenotype. To understand phenotypic shifts transpiring within endothelial cells in PH, we injected rats with alkaloid monocrotaline to induce PH and measured lung tissue levels of endothelial-specific protein and critical differentiation marker vascular endothelial (VE)-cadherin. VE-cadherin expression by immonoblotting declined significantly 24 h and 15 days postinjection to rebound to baseline at 30 days. There was a concomitant increase in transcriptional repressors Snail and Slug, along with a reduction in VE-cadherin mRNA. Mesenchymal markers α-smooth muscle actin and vimentin were upregulated by immunohistochemistry and immunoblotting, and α-smooth muscle actin was colocalized with endothelial marker platelet endothelial cell adhesion molecule-1 by confocal microscopy. Apoptosis was limited in this model, especially in the 24-h time point. In addition, monocrotaline resulted in activation of protein kinase B/Akt, endothelial nitric oxide synthase (eNOS), nuclear factor (NF)-κB, and increased lung tissue nitrotyrosine staining. To understand the etiological relationship between nitrosative stress and VE-cadherin suppression, we incubated cultured rat lung endothelial cells with endothelin-1, a vasoconstrictor and pro-proliferative agent in pulmonary arterial hypertension. This resulted in activation of eNOS, NF-κB, and Akt, in addition to induction of Snail, downregulation of VE-cadherin, and synthesis of vimentin. These effects were blocked by eNOS inhibitor N(ω)-nitro-l-arginine methyl ester. We propose that transcriptional repression of VE-cadherin by nitrosative stress is involved in endothelial-mesenchymal transdifferentiation in experimental PH.
authors.affiliation: First Department of Critical Care Medicine & Pulmonary Services, GP Livanos and M Simou Laboratories, University of Athens Medical School, Evangelismos Hospital, Athens, Greece;
authors.forename: Ioanna
authors.initials: I
authors.lastname: Nikitopoulou
authors.affiliation: First Department of Critical Care Medicine & Pulmonary Services, GP Livanos and M Simou Laboratories, University of Athens Medical School, Evangelismos Hospital, Athens, Greece; Second Department of Critical Care, University of Athens Medical School, Attikon Hospital, Haidari, Greece; and.
authors.forename: Stylianos E
authors.initials: SE
authors.lastname: Orfanos
authors.affiliation: First Department of Critical Care Medicine & Pulmonary Services, GP Livanos and M Simou Laboratories, University of Athens Medical School, Evangelismos Hospital, Athens, Greece;
authors.forename: Anastasia
authors.initials: A
authors.lastname: Kotanidou
authors.affiliation: Department of Biomedical Research, FORTH, University of Ioannina Medical School Ioannina, Greece.
authors.forename: Violetta
authors.initials: V
authors.lastname: Maltabe
authors.affiliation: First Department of Critical Care Medicine & Pulmonary Services, GP Livanos and M Simou Laboratories, University of Athens Medical School, Evangelismos Hospital, Athens, Greece;
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Manitsopoulos
authors.affiliation: Department of Biomedical Research, FORTH, University of Ioannina Medical School Ioannina, Greece.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Karras
authors.affiliation: Department of Biomedical Research, FORTH, University of Ioannina Medical School Ioannina, Greece.
authors.forename: Panos
authors.initials: P
authors.lastname: Kouklis
authors.affiliation: Second Department of Critical Care, University of Athens Medical School, Attikon Hospital, Haidari, Greece; and.
authors.forename: Apostolos
authors.initials: A
authors.lastname: Armaganidis
authors.affiliation: First Department of Critical Care Medicine & Pulmonary Services, GP Livanos and M Simou Laboratories, University of Athens Medical School, Evangelismos Hospital, Athens, Greece; Second Department of Critical Care, University of Athens Medical School, Attikon Hospital, Haidari, Greece; and maniatisnikolaos@yahoo.com.
authors.forename: Nikolaos A
authors.initials: NA
authors.lastname: Maniatis
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D017209:Apoptosis; D015820:Cadherins / Q000235:genetics / Q000378:metabolism*; D054338:Cell Transdifferentiation; D002478:Cells, Cultured; D015536:Down-Regulation; D042783:Endothelial Cells / Q000502:physiology*; D019332:Endothelin-1 / Q000502:physiology; D004730:Endothelium, Vascular / Q000473:pathology; D004789:Enzyme Activation; D020868:Gene Silencing; D006976:Hypertension, Pulmonary / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D008168:Lung / Q000473:pathology; D016686:Monocrotaline; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D017208:Rats, Wistar; D014158:Transcription, Genetic; D000099152:Cadherin 5
chemical_list: D015703:Antigens, CD; D015820:Cadherins; D019332:Endothelin-1; D016686:Monocrotaline; D052250:Nitric Oxide Synthase Type III; D000099152:Cadherin 5; C496316:Nos3 protein, rat
keywords: endothelial-to-mesenchymal transition; endothelin-1; monocrotaline; pulmonary arterial hypertension; vascular endothelial-cadherin