title: Hypoxia up-regulates expression of Eph receptors and ephrins in mouse skin.
abstract: Eph receptor tyrosine kinases and their ligands (ephrins) are key players during the development of the embryonic vasculature; however, their role and regulation in adult angiogenesis remain to be defined. Both receptors and ligands have been shown to be up-regulated in a variety of tumors. To address the hypothesis that hypoxia is an important regulator of Ephs/ephrins expression, we developed a mouse skin flap model of hypoxia. We demonstrate that our model truly represents segmental skin hypoxia by applying four independent methods: continuous measurement of partial cutaneous oxygen tension, monitoring of tissue lactate/pyruvate ratio, time course of hypoxia-inducible factor-1alpha (HIF-1alpha) induction, and localization of stabilized HIF-1alpha by immunofluorescence in the hypoxic skin flap. Our experiments indicate that hypoxia up-regulates not only HIF-1alpha and vascular endothelial growth factor (VEGF) expression, but also Ephs and ephrins of both A and B subclasses in the skin. In addition, we show that in Hep3B and PC-3 cells, the hypoxia-induced up-regulation of Ephs and ephrins is abrogated by small interfering RNA-mediated down-regulation of HIF-1alpha. These novel findings shed light on the role of this versatile receptor/ligand family in adult angiogenesis. Furthermore, our model offers considerable potential for analyzing distinct mechanisms of neovascularization in gene-targeted mice.
authors.affiliation: Department of Nephrology and Hypertension, University of Bern, Bern, Switzerland.
authors.forename: Meri M
authors.initials: MM
authors.lastname: Vihanto
authors.forename: Jan
authors.initials: J
authors.lastname: Plock
authors.forename: Dominique
authors.initials: D
authors.lastname: Erni
authors.forename: Brigitte M
authors.initials: BM
authors.lastname: Frey
authors.forename: Felix J
authors.initials: FJ
authors.lastname: Frey
authors.forename: Uyen
authors.initials: U
authors.lastname: Huynh-Do
mesh_terms: D000818:Animals; D001706:Biopsy; D045744:Cell Line, Tumor; D015536:Down-Regulation; D036382:Ephrin-A1 / Q000096:biosynthesis; D036388:Ephrin-B2 / Q000096:biosynthesis; D036342:Ephrins / Q000096:biosynthesis*; D005786:Gene Expression Regulation; D006801:Humans; D000860:Hypoxia; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D015151:Immunoblotting; D007150:Immunohistochemistry; D008024:Ligands; D051379:Mice; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009389:Neovascularization, Pathologic; D010100:Oxygen / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D036104:Receptor, EphA2 / Q000096:biosynthesis; D036224:Receptor, EphB4 / Q000096:biosynthesis; D036081:Receptors, Eph Family / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D012867:Skin / Q000378:metabolism*; D013997:Time Factors; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D014945:Wound Healing
chemical_list: D036382:Ephrin-A1; D036388:Ephrin-B2; D036342:Ephrins; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008024:Ligands; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D042461:Vascular Endothelial Growth Factor A; D036104:Receptor, EphA2; D036224:Receptor, EphB4; D036081:Receptors, Eph Family; D010100:Oxygen