title: 4-Hydroxy-2-nonenal upregulates and phosphorylates cytosolic phospholipase A(2) in cultured Ra2 microglial cells via MAPK pathways.
abstract: Several studies have suggested the involvement of neuroinflammation in the pathomechanism of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). We recently demonstrated increased levels of protein-bound 4-hydroxy-2-nonenal (HNE) as a highly reactive lipid peroxidation product and cytosolic phospholipase A(2) (cPLA(2)) as a proinflammatory enzyme in glial cells as well as motor neurons in the spinal cord of sporadic ALS patients. However, a link between HNE and cPLA(2) in ALS remains to be determined. To address this issue, we investigated effects of HNE stimulation on the state of cPLA(2) expression in cultured microglial cell line (Ra2). Exposure of Ra2 cells to HNE significantly increased expression levels of cPLA(2) and its activated form phosphorylated at amino acid residue S(505) (p-cPLA(2)) on immunoblots. Pretreatment of Ra2 cells with the antioxidant N-acetylcysteine, the extracellular signal-regulated kinase (ERK) inhibitor PD98059 or the p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580 prevented the HNE-induced increased expression of cPLA(2) and p-cPLA(2). Immunocytochemical analysis revealed that staining for p-cPLA(2) in Ra2 cells was localized in the cytoplasm and more intense in the HNE-stimulated group than in the vehicle group. The present results provide in vitro evidence that HNE upregulates and phosphorylates cPLA(2) in microglia via the ERK and p38 MAPK pathways.
authors.affiliation: Department of Pathology, Tokyo Women's Medical University, Shinjuku-ku, Tokyo, Japan. shibatan@research.twmu.ac.jp
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Shibata
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Kato
authors.forename: Yuri
authors.initials: Y
authors.lastname: Inose
authors.forename: Atsuko
authors.initials: A
authors.lastname: Hiroi
authors.forename: Tomoko
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Shunichi
authors.initials: S
authors.lastname: Morikawa
authors.forename: Makoto
authors.initials: M
authors.lastname: Sawada
authors.forename: Makio
authors.initials: M
authors.lastname: Kobayashi
mesh_terms: D000447:Aldehydes / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism; D004789:Enzyme Activation / Q000502:physiology; D054513:Group IV Phospholipases A2 / Q000378:metabolism*; D007150:Immunohistochemistry; D015227:Lipid Peroxidation; D051379:Mice; D017628:Microglia / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology; D010766:Phosphorylation; D015398:Signal Transduction / Q000502:physiology*; D015854:Up-Regulation
chemical_list: D000447:Aldehydes; D020928:Mitogen-Activated Protein Kinases; D054513:Group IV Phospholipases A2; C027576:4-hydroxy-2-nonenal