title: Nerve growth factor protects against 6-hydroxydopamine-induced oxidative stress by increasing expression of heme oxygenase-1 in a phosphatidylinositol 3-kinase-dependent manner.
abstract: The survival signal elicited by the phosphatidylinositol 3-kinase (PI3K)/Akt1 pathway has been correlated with inactivation of pro-apoptotic proteins and attenuation of the general stress-induced increase in reactive oxygen species (ROS). However, the mechanisms by which this pathway regulates intracellular ROS levels remain largely unexplored. In this study, we demonstrate that nerve growth factor (NGF) prevents the accumulation of ROS in dopaminergic PC12 cells challenged with the Parkinson's disease-related neurotoxin 6-hydroxydopamine (6-OHDA) by a mechanism that involves PI3K/Akt-dependent induction of the stress response protein heme oxygenase-1 (HO-1). The effect of NGF was mimicked by induction of HO-1 expression with CoCl(2); by treatment with bilirubin, an end product of heme catabolism; and by infection with a retroviral expression vector for human HO-1. The relevance of HO-1 in NGF-induced ROS reduction was further demonstrated by the evidence that cells treated with the HO-1 inhibitor tin-protoporphyrin or infected with a retroviral expression vector for antisense HO-1 exhibited enhanced ROS release in response to 6-OHDA, despite the presence of the neurotrophin. Inhibition of PI3K prevented NGF induction of HO-1 mRNA and protein and partially reversed its protective effect against 6-OHDA-induced ROS release. By contrast, cells transfected with a membrane-targeted active version of Akt1 exhibited increased HO-1 expression, even in the absence of NGF, and displayed a greatly attenuated production of ROS and apoptosis in response to 6-OHDA. These observations indicate that the PI3K/Akt pathway controls the intracellular levels of ROS by regulating the expression of the antioxidant enzyme HO-1.
authors.affiliation: Instituto de Investigaciones Biomédicas and the Departamento de Bioquimica, Facultad de Medicina, Universidad Autónoma de Madrid, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Salinas
authors.forename: Raquel
authors.initials: R
authors.lastname: Diaz
authors.forename: Nader G
authors.initials: NG
authors.lastname: Abraham
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Ruiz de Galarreta
authors.forename: Antonio
authors.initials: A
authors.lastname: Cuadrado
mesh_terms: D018663:Adrenergic Agents / Q000494:pharmacology; D000818:Animals; D017304:Annexin A5 / Q000494:pharmacology; D017209:Apoptosis; D001663:Bilirubin / Q000378:metabolism; D002469:Cell Separation; D003035:Cobalt / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D049452:Green Fluorescent Proteins; D006419:Heme Oxygenase (Decyclizing) / Q000378:metabolism*; D051547:Heme Oxygenase-1; D006801:Humans; D015151:Immunoblotting; D008164:Luminescent Proteins / Q000378:metabolism; D008565:Membrane Proteins; D018613:Microscopy, Confocal; D020932:Nerve Growth Factor / Q000378:metabolism / Q000494:pharmacology*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D018384:Oxidative Stress; D016627:Oxidopamine / Q000494:pharmacology*; D016716:PC12 Cells; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014162:Transfection; D015854:Up-Regulation
chemical_list: D018663:Adrenergic Agents; D017304:Annexin A5; D001663:Bilirubin; D003035:Cobalt; D049452:Green Fluorescent Proteins; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D008164:Luminescent Proteins; D008565:Membrane Proteins; D020932:Nerve Growth Factor; D016376:Oligonucleotides, Antisense; D016627:Oxidopamine; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; C496541:HMOX1 protein, human; C494918:AKT1 protein, human; C494920:Akt1 protein, rat; C018021:cobaltous chloride