title: Inhibition of ARNT severely compromises endothelial cell viability and function in response to moderate hypoxia.
abstract: Hypoxia inducible factor (HIF) is a master heterodimeric transcriptional regulator of oxygen (O(2)) homeostasis critical to proper angiogenic responses. Due to the distinctive coexpression of HIF-1α and HIF-2α subunits in endothelial cells, our goal was to examine the genetic elimination of HIF transcriptional activity in response to physiological hypoxic conditions by using a genetic model in which the required HIF-β subunit (ARNT, Aryl hydrocarbon Receptor Nuclear Translocator) to HIF transcriptional responses was depleted. Endothelial cells (ECs) and aortic explants were isolated from Arnt                         (                            loxP/loxP                         ) mice and infected with Adenovirus-Cre/GFP or control-GFP. We observed that moderate levels of 2.5 % O(2) promoted vessel sprouting, growth, and branching in control aortic ring assays while growth from Adenovirus-Cre infected explants was compromised. Primary Adenovirus-Cre infected EC cultures featured adverse migration and tube formation phenotypes. Primary pulmonary or cardiac ARNT-deleted ECs also failed to proliferate and survive in response to 8 or 2.5 % O(2) and hydrogen peroxide treatment. Our data demonstrates that ARNT promotes EC migration and vessel outgrowth and is indispensible for the proliferation and preservation of ECs in response to the physiological environmental cue of hypoxia. Thus, these results demonstrate that ARNT plays a critical intrinsic role in ECs and support an important collaboration between HIF-1 and HIF-2 transcriptional activity in these cells.
authors.affiliation: Case Cardiovascular Research Institute, Department of Medicine, University Hospitals Harrington Heart and Vascular Institute, Case Western Reserve University School of Medicine, 2103 Cornell Road, Rm. 4-532, Cleveland, OH 44106, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Han
authors.forename: Ke
authors.initials: K
authors.lastname: Yang
authors.forename: Aaron
authors.initials: A
authors.lastname: Proweller
authors.forename: Guangjin
authors.initials: G
authors.lastname: Zhou
authors.forename: Mukesh K
authors.initials: MK
authors.lastname: Jain
authors.forename: Diana L
authors.initials: DL
authors.lastname: Ramirez-Bergeron
mesh_terms: D000818:Animals; D001011:Aorta / Q000254:growth & development; D017209:Apoptosis; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator / Q000037:antagonists & inhibitors*; D001483:Base Sequence; D015687:Cell Hypoxia; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D017931:DNA Primers; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000502:physiology; D066298:In Vitro Techniques; D051379:Mice; D018919:Neovascularization, Physiologic; D060888:Real-Time Polymerase Chain Reaction
chemical_list: C497396:ARNT protein, human; D017931:DNA Primers; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator