title: Arachidonic acid induces brain endothelial cell apoptosis via p38-MAPK and intracellular calcium signaling.
abstract: Arachidonic acid (AA), a bioactive fatty acid whose levels increase during neuroinflammation, contributes to cerebral vascular damage and dysfunction. However, the mode of injury and underlying signaling mechanisms remain unknown. Challenge of primary human brain endothelial cells (HBECs) with AA activated a stress response resulting in caspase-3 activation, poly(ADP-ribose) polymerase cleavage, and disruption of monolayer integrity. AA also induced loss of mitochondrial membrane potential and cytochrome c release consistent with activation of intrinsic apoptosis. HBEC stimulation with AA resulted in sustained p38-MAPK activation and subsequent phosphorylation of mitogen-activated protein kinase activated protein-2 (MAPKAP-2) kinase and heat shock protein-27 (Hsp27). Conversely, other unsaturated and saturated fatty acids had no effect. Pharmacological and RNA interference-mediated p38α or p38β suppression abrogated AA signaling to caspase-3 and Hsp27, suggesting involvement of both p38 isoforms in AA-induced HBEC apoptosis. Hsp27 silencing also blocked caspase-3 activation. AA stimulated intracellular calcium release, which was attenuated by inositol 1,4,5-trisphosphate (IP3) receptor antagonists. Blockade of intracellular calcium release decreased caspase-3 activation, but had no effect on AA-induced p38-MAPK activation. However, inhibition of p38-MAPK or blockade of intracellular calcium mobilization abrogated AA-induced cytochrome c release. AA-induced caspase-3 activation was abrogated by pharmacological inhibition of lipooxygenases. These findings support a previously unrecognized signaling cooperation between p38-MAPK/MAPKAP-2/Hsp27 and intracellular calcium release in AA-induced HBEC apoptosis and suggest its relevance to neurological disorders associated with vascular inflammation.
authors.affiliation: Signal Transduction Laboratory, Methodist Research Institute, Indiana University Health, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: Evans
authors.affiliation: Signal Transduction Laboratory, Methodist Research Institute, Indiana University Health, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: YooSeung
authors.initials: Y
authors.lastname: Ko
authors.affiliation: Signal Transduction Laboratory, Methodist Research Institute, Indiana University Health, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Wilmer
authors.initials: W
authors.lastname: Mata
authors.affiliation: Signal Transduction Laboratory, Methodist Research Institute, Indiana University Health, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Saquib
authors.affiliation: Signal Transduction Laboratory, Methodist Research Institute, Indiana University Health, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Joel
authors.initials: J
authors.lastname: Eldridge
authors.affiliation: Goodman Campbell Brain and Spine, Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Aaron
authors.initials: A
authors.lastname: Cohen-Gadol
authors.affiliation: Division of Clinical Neuroscience, Edinburgh University, Edinburgh, UK.
authors.forename: H Anne
authors.initials: HA
authors.lastname: Leaver
authors.affiliation: Signal Transduction Laboratory, Methodist Research Institute, Indiana University Health, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Shukun
authors.initials: S
authors.lastname: Wang
authors.affiliation: Signal Transduction Laboratory, Methodist Research Institute, Indiana University Health, Indiana University School of Medicine, Indianapolis, IN, USA; Department of Pharmacology, Indiana University School of Medicine, Indianapolis, IN, USA. Electronic address: mrizzo@iuhealth.org.
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Rizzo
mesh_terms: D017209:Apoptosis; D016718:Arachidonic Acid / Q000378:metabolism*; D001921:Brain / Q000166:cytology*; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D053148:Caspase 3 / Q000378:metabolism; D049109:Cell Proliferation; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism / Q000473:pathology*; D020868:Gene Silencing; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D058945:Lipoxygenases / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008928:Mitochondria / Q000473:pathology; D048308:Mitogen-Activated Protein Kinase 14 / Q000378:metabolism; D018832:Molecular Chaperones; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D034622:RNA Interference; D000099190:MAP-Kinase-Activated Kinase 2
chemical_list: D016718:Arachidonic Acid; D002118:Calcium; D053148:Caspase 3; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D058945:Lipoxygenases; D048308:Mitogen-Activated Protein Kinase 14; D018832:Molecular Chaperones; D017346:Protein Serine-Threonine Kinases; D000099190:MAP-Kinase-Activated Kinase 2; C057725:HSPB1 protein, human; C505407:CASP3 protein, human
keywords: Apoptosis; Arachidonic Acid; Brain endothelial cells; Calcium; p38-MAPK