title: Expression of angiopoietin-1 in hypoxic pericytes: Regulation by hypoxia-inducible factor-2α and participation in endothelial cell migration and tube formation.
abstract: We previously reported that hypoxia increases angiopoietin-1 (Ang1), but not Ang2, mRNA expression in bovine retinal pericytes (BRP). However, the mechanism underlying Ang1 expression is unknown. Here, we report that Ang1 protein expression increased in hypoxic BRP in a dose- and time-dependent manner. This increase was accompanied by an increase in hypoxia-inducible factor-2α (HIF2α) expression. Transfection with an antisense oligonucleotide for HIF2α partially inhibited the hypoxia-induced increase in Ang1 expression. HIF2α overexpression further potentiated hypoxia-stimulated Ang1 expression, suggesting that HIF2α plays an important role in Ang1 regulation in BRP. When fused the Ang1 promoter (-3040 to +199) with the luciferase reporter gene, we found that hypoxia significantly increased promoter activity by 4.02 ± 1.68 fold. However, progressive 5'-deletions from -3040 to -1799, which deleted two putative hypoxia response elements (HRE), abolished the hypoxia-induced increase in promoter activity. An electrophoretic mobility shift assay revealed that HIF2α was predominantly bound to a HRE site, located specifically at nucleotides -2715 to -2712. Finally, treatment with conditioned medium obtained from hypoxic pericytes stimulated endothelial cell migration and tube formation, which was completely blocked by co-treatment with anti-Ang1 antibody. This study is the first to demonstrate that hypoxia upregulates Ang1 expression via HIF2α-mediated transcriptional activation in pericytes, which plays a key role in angiogenesis.
authors.affiliation: Department of Molecular Medicine, School of Medicine, Ewha Womans University, Seoul 07985, Republic of Korea; Ewha Tonsil-derived mesenchymal Stem cells Research Center (ETSRC), School of Medicine, Ewha Womans University, Seoul 07985, Republic of Korea.
authors.forename: Yoon Shin
authors.initials: YS
authors.lastname: Park
authors.affiliation: Department of Molecular Medicine, School of Medicine, Ewha Womans University, Seoul 07985, Republic of Korea; Ewha Tonsil-derived mesenchymal Stem cells Research Center (ETSRC), School of Medicine, Ewha Womans University, Seoul 07985, Republic of Korea.
authors.forename: Gyungah
authors.initials: G
authors.lastname: Kim
authors.affiliation: Department of Molecular Medicine, School of Medicine, Ewha Womans University, Seoul 07985, Republic of Korea; Ewha Tonsil-derived mesenchymal Stem cells Research Center (ETSRC), School of Medicine, Ewha Womans University, Seoul 07985, Republic of Korea.
authors.forename: Yoon Mi
authors.initials: YM
authors.lastname: Jin
authors.affiliation: Department of Molecular Medicine, School of Medicine, Ewha Womans University, Seoul 07985, Republic of Korea.
authors.forename: Jee Young
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Division of Allergic and Pulmonary Medicine, College of Medicine, Chung Ang University, Seoul 06974, Republic of Korea.
authors.forename: Jong Wook
authors.initials: JW
authors.lastname: Shin
authors.affiliation: Department of Molecular Medicine, School of Medicine, Ewha Womans University, Seoul 07985, Republic of Korea; Ewha Tonsil-derived mesenchymal Stem cells Research Center (ETSRC), School of Medicine, Ewha Womans University, Seoul 07985, Republic of Korea. Electronic address: inhojo@ewha.ac.kr.
authors.forename: Inho
authors.initials: I
authors.lastname: Jo
mesh_terms: D042683:Angiopoietin-1 / Q000378:metabolism*; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D001808:Blood Vessels / Q000166:cytology / Q000254:growth & development*; D002417:Cattle; D015687:Cell Hypoxia / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000502:physiology; D018919:Neovascularization, Physiologic / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism; D020286:Pericytes / Q000166:cytology* / Q000502:physiology*; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D042683:Angiopoietin-1; D051792:Basic Helix-Loop-Helix Proteins; D010100:Oxygen; D000099162:Endothelial PAS Domain-Containing Protein 1
keywords: Angiogenesis; Angiopoietin-1; Endothelial cells; Hypoxia; Hypoxia-inducible factor-2α; Pericytes