title: Ceramide-activated phosphatase mediates fatty acid-induced endothelial VEGF resistance and impaired angiogenesis.
abstract: Endothelial dysfunction, including endothelial hyporesponsiveness to prototypical angiogenic growth factors and eNOS agonists, underlies vascular pathology in many dysmetabolic states. We investigated effects of a saturated free fatty acid, palmitic acid (PA), on endothelial cell responses to VEGF. PA-pretreated endothelial cells had markedly diminished Akt, eNOS, and ERK activation responses to VEGF, despite normal VEGFR2 phosphorylation. PA inhibited VEGF-induced angiogenic cord formation in Matrigel, and PA-treated endothelial cells accumulated early species (C16) ceramide. The serine palmitoyltransferase inhibitor myriocin reversed these defects. Protein phosphatase 2A (PP2A) became more eNOS-associated in PA-treated cells; the PP2A inhibitor okadaic acid reversed PA-induced signaling defects. Mice fed a diet high in saturated fat for 2 to 3 weeks had impaired i) aortic Akt and eNOS phosphorylation to infused VEGF, ii) ear angiogenic responses to intradermal adenoviral-VEGF injection, and iii) vascular flow recovery to hindlimb ischemia as indicated by laser Doppler and αVβ3 SPECT imaging. High-fat feeding did not impair VEGF-induced signaling or angiogenic responses in mice with reduced serine palmitoyltransferase expression. Thus, de novo ceramide synthesis is required for these detrimental PA effects. The findings demonstrate an endothelial VEGF resistance mechanism conferred by PA, which comprises ceramide-induced, PP2A-mediated dephosphorylation of critical activation sites on enzymes central to vascular homeostasis and angiogenesis. This study defines potential molecular targets for preservation of endothelial function in metabolic syndrome.
authors.affiliation: Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut; Department of Immunobiology, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut; Raymond and Beverly Sackler Foundation Cardiovascular Laboratory, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Vishal C
authors.initials: VC
authors.lastname: Mehra
authors.affiliation: Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut; Department of Immunobiology, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut; Raymond and Beverly Sackler Foundation Cardiovascular Laboratory, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Elias
authors.initials: E
authors.lastname: Jackson
authors.affiliation: Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Xian M
authors.initials: XM
authors.lastname: Zhang
authors.affiliation: SUNY Downstate Medical Center, Brooklyn, New York.
authors.forename: Xian-Cheng
authors.initials: XC
authors.lastname: Jiang
authors.affiliation: Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Lawrence W
authors.initials: LW
authors.lastname: Dobrucki
authors.affiliation: Department of Pharmacology, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Jun
authors.initials: J
authors.lastname: Yu
authors.affiliation: Department of Pharmacology, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Pascal
authors.initials: P
authors.lastname: Bernatchez
authors.affiliation: Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Sinusas
authors.affiliation: Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut; Howard Hughes Medical Institute, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Gerald I
authors.initials: GI
authors.lastname: Shulman
authors.affiliation: Department of Pharmacology, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: William C
authors.initials: WC
authors.lastname: Sessa
authors.affiliation: Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut; Department of Immunobiology, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut; Raymond and Beverly Sackler Foundation Cardiovascular Laboratory, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Timur O
authors.initials: TO
authors.lastname: Yarovinsky
authors.affiliation: Department of Internal Medicine, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut; Department of Immunobiology, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut; Raymond and Beverly Sackler Foundation Cardiovascular Laboratory, Yale Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut. Electronic address: jeffrey.bender@yale.edu.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Bender
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000473:pathology; D001158:Arteries / Q000187:drug effects / Q000254:growth & development; D002417:Cattle; D002518:Ceramides / Q000494:pharmacology*; D059305:Diet, High-Fat; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D057895:Haploinsufficiency; D006614:Hindlimb / Q000098:blood supply / Q000473:pathology; D006801:Humans; D007511:Ischemia / Q000473:pathology; D008810:Mice, Inbred C57BL; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D009569:Nitric Oxide / Q000096:biosynthesis; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D019308:Palmitic Acid / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D054648:Protein Phosphatase 2 / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051102:Serine C-Palmitoyltransferase / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*
chemical_list: D002518:Ceramides; D042461:Vascular Endothelial Growth Factor A; D019308:Palmitic Acid; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D051102:Serine C-Palmitoyltransferase; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D054648:Protein Phosphatase 2