title: Endothelial Akt1 mediates angiogenesis by phosphorylating multiple angiogenic substrates.
abstract: The PI3K/Akt pathway is necessary for several key endothelial cell (EC) functions, including cell growth, migration, survival, and vascular tone. However, existing literature supports the idea that Akt can be either pro- or antiangiogenic, possibly due to compensation by multiple isoforms in the EC when a single isoform is deleted. Thus, biochemical, genetic, and proteomic studies were conducted to examine isoform-substrate specificity for Akt1 vs. Akt2. In vitro, Akt1 preferentially phosphorylates endothelial nitric oxide synthase (eNOS) and promotes NO release, whereas nonphysiological overexpression of Akt2 can bypass the loss of Akt1. Conditional deletion of Akt1 in the EC, in the absence or presence of Akt2, retards retinal angiogenesis, implying that Akt1 exerts a nonredundant function during physiological angiogenesis. Finally, proteomic analysis of Akt substrates isolated from Akt1- or Akt2-deficient ECs documents that phosphorylation of multiple Akt substrates regulating angiogenic signaling is reduced in Akt1-deficient, but not Akt2-deficient, ECs, including eNOS and Forkhead box proteins. Therefore, Akt1 promotes angiogenesis largely due to phosphorylation and regulation of important downstream effectors that promote aspects of angiogenic signaling.
authors.affiliation: Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520; Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT 06520;
authors.forename: Monica Y
authors.initials: MY
authors.lastname: Lee
authors.affiliation: Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520; Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT 06520;
authors.forename: Amelia K
authors.initials: AK
authors.lastname: Luciano
authors.affiliation: Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT 06520; Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520;
authors.forename: Eric
authors.initials: E
authors.lastname: Ackah
authors.affiliation: Institut d'Investigaciones Biomèdiques August Pi i Sunyer, Barcelona, Spain; and.
authors.forename: Juan
authors.initials: J
authors.lastname: Rodriguez-Vita
authors.affiliation: Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT 06520; Departments of Pathology and Biomedical Engineering and.
authors.forename: Tara A
authors.initials: TA
authors.lastname: Bancroft
authors.affiliation: Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT 06520; Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520;
authors.forename: Anne
authors.initials: A
authors.lastname: Eichmann
authors.affiliation: Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT 06520; Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520;
authors.forename: Michael
authors.initials: M
authors.lastname: Simons
authors.affiliation: Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT 06520; Departments of Pathology and Biomedical Engineering and.
authors.forename: Themis R
authors.initials: TR
authors.lastname: Kyriakides
authors.affiliation: Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT 06520; Institut d'Investigaciones Biomèdiques August Pi i Sunyer, Barcelona, Spain; and Biochemistry and Molecular Genetics, Hospital Clinic of Barcelona, Networked Biomedical Research Center of Hepatic and Digestive Diseases (CIBERehd), 08036 Barcelona, Spain morales@clinic.ub.es william.sessa@yale.edu.
authors.forename: Manuel
authors.initials: M
authors.lastname: Morales-Ruiz
authors.affiliation: Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520; Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT 06520; Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520; morales@clinic.ub.es william.sessa@yale.edu.
authors.forename: William C
authors.initials: WC
authors.lastname: Sessa
mesh_terms: D000818:Animals; D002461:Cell Line, Transformed; D004730:Endothelium, Vascular / Q000378:metabolism*; D008168:Lung / Q000098:blood supply / Q000166:cytology; D051379:Mice; D018345:Mice, Knockout; D018919:Neovascularization, Physiologic / Q000502:physiology*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D009588:Nitrogen Mustard Compounds / Q000378:metabolism; D010766:Phosphorylation / Q000502:physiology; D040901:Proteomics; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D012160:Retina / Q000473:pathology; D012171:Retinal Vessels / Q000378:metabolism* / Q000473:pathology; D015398:Signal Transduction / Q000502:physiology; D013379:Substrate Specificity
chemical_list: D009588:Nitrogen Mustard Compounds; C008634:nitrocaphane; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; C514862:Akt1 protein, mouse; C494922:Akt2 protein, mouse; D051057:Proto-Oncogene Proteins c-akt
keywords: development; kinase; phosphoproteomics