title: Sphingomyelin Regulates the Activity of Secretory Phospholipase A2 in the Plasma Membrane.
abstract: We examined the effect of the cellular sphingolipid level on the release of arachidonic acid (AA) and the activity of secretory phospholipase A2 (sPLA2 ) using two Chinese hamster ovary (CHO)-K1 cell mutants, LY-B and LY-A cells, deficient in sphingolipid synthesis. In LY-B cells, deficiency of sphingolipids enhanced the release of AA induced by bee venom sPLA2-III or human sPLA2-V. These alterations were reversed by replenishment of exogenous sphingomyelin (SM). In LY-A cells, deficiency of SM increased the release of AA induced by sPLA2. In CHO-K1 cells, decrease and increase of SM level in the plasma membrane by pharmacological methods increased and inhibited the release of AA, respectively. SM inhibited the activity of sPLA2 in vitro. Niemann-Pick disease type C (NPC) is a lysosomal storage disorder caused by mutation of either the NPC1 or NPC2 gene, and is characterized by accumulation of cholesterol and sphingolipids including SM in late endosomes/lysosomes. Increased levels of AA and sPLA2 activity are involved in various neurodegenerative diseases. In CHO cells lacking NPC1 (A101 cells), SM level was lower in the plasma membrane, while it was higher in late endosomes/lysosomes. The release of AA induced by sPLA2 was increased in A101 cells than that in parental cells (JP17 cells), which was attenuated by adding exogenous SM. In addition, sPLA2 -III-induced cytotoxicity in A101 cells was much higher than that in JP17 cells. These results suggest that SM in the plasma membrane plays important roles in regulating sPLA2 activity and the enzyme-induced cytotoxicity in A101 cells.
authors.affiliation: Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakamura
authors.affiliation: Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Wakita
authors.affiliation: Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675, Japan.
authors.forename: Kana
authors.initials: K
authors.lastname: Yasufuku
authors.affiliation: Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675, Japan.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Makiyama
authors.affiliation: Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675, Japan.
authors.forename: Misa
authors.initials: M
authors.lastname: Waraya
authors.affiliation: Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675, Japan.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Hashimoto
authors.affiliation: Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Murayama
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000096:biosynthesis*; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D054520:Group III Phospholipases A2 / Q000378:metabolism / Q000494:pharmacology; D054505:Group V Phospholipases A2 / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D008562:Membrane Glycoproteins / Q000172:deficiency; D008954:Models, Biological; D052556:Niemann-Pick Disease, Type C / Q000201:enzymology*; D054497:Phospholipases A2, Secretory / Q000378:metabolism* / Q000494:pharmacology; D013109:Sphingomyelins / Q000172:deficiency / Q000378:metabolism*
chemical_list: D008562:Membrane Glycoproteins; D013109:Sphingomyelins; D016718:Arachidonic Acid; D054520:Group III Phospholipases A2; D054505:Group V Phospholipases A2; C516299:PLA2G5 protein, human; D054497:Phospholipases A2, Secretory
keywords: CHINESE HAMSTER OVARY CELLS; GROUP III SECRETORY PHOSPHOLIPASE A2; GROUP V SECRETORY PHOSPHOLIPASE A2; LY-A; LY-B; NIEMANN-PICK DISEASE TYPE C; SPHINGOMYELIN