Amyloid beta(1-42) and its beta(25-35) fragment induce activation and membrane translocation of cytosolic phospholipase A2 in bovine retina capillary pericytes.
We investigated changes in cytosolic phospholipase A(2) (cPLA(2)) and calcium-independent PLA(2) (iPLA(2)) activities in bovine retina capillary pericytes after stimulation with 50 microM amyloid-beta (Abeta) (1-42) and its (25-35) fragment, over 24 h (mild, sublethal model of cell damage). In the presence of Abeta peptides, we found that cPLA(2) activity was increased and translocated from the cytosolic fraction to the membrane system, particularly in the nuclear region. Reversed-sequence Abeta(35-25) peptide did not stimulate or induce cPLA(2) translocation. Exposure to both Abeta peptides had no significant effect on cPLA(2) protein content as tested by Western immunoblot analysis. The addition of Abetas to quiescent pericytes was followed by phosphorylation of cPLA(2) and arachidonic acid release. Treatment with inhibitors (AACOCF(3), staurosporine and cycloheximide) resulted in a sharp decrease in basal and stimulated cPLA(2) activity. Inactivating effects of bromoenol lactone (BEL), inhibitor of iPLA(2), demonstrated that the stimulation of total PLA(2) activity by Abetas was mediated by both PLA(2) enzymes. Taken together with our previous observations that both Abeta peptides may induce hydrolysis of phosphatidylcholine, the present results provide evidence that this process is cooperatively mediated by cPLA(2) activation/translocation and iPLA(2) activation. The effect is very likely triggered by a mild prooxidant mechanism which was not able to divert the cell to degeneration. The data confirm the hypothesis that pericytes could be a target of potential vascular damage and reactivity during processes involving amyloid accumulation.
Anfuso
Carmelina Daniela
CD
Department of Biochemistry, Faculty of Medicine, University of Catania, Viale A. Doria 6, 95125 Catania, Italy.
Assero
Giovanna
G
Lupo
Gabriella
G
Nicotra
Ambra
A
Cannavò
Giuseppe
G
Strosznajder
Robert P
RP
Rapisarda
Piero
P
Pluta
Ryszard
R
Alberghina
Mario
M
D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D001095:Arachidonic Acids / Q000494:pharmacology; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D054522:Group VI Phospholipases A2; D009281:Naphthalenes / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology*; D020286:Pericytes / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000378:metabolism*; D054467:Phospholipases A2; D010766:Phosphorylation; D011065:Poly(ADP-ribose) Polymerases / Q000737:chemistry / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D011753:Pyrones / Q000494:pharmacology; D012161:Retinal Artery / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D019311:Staurosporine / Q000494:pharmacology; D013347:Subcellular Fractions / Q000201:enzymology; D051028:bcl-2-Associated X Protein
D016229:Amyloid beta-Peptides; D001095:Arachidonic Acids; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D009281:Naphthalenes; D009842:Oligopeptides; D010446:Peptide Fragments; D019253:Proto-Oncogene Proteins c-bcl-2; D011753:Pyrones; C075222:amyloid beta-protein (1-42); C074636:amyloid beta-protein (25-35); C108637:aspartyl-glutamyl-valyl-aspartal; D051028:bcl-2-Associated X Protein; C081565:arachidonyltrifluoromethane; D016718:Arachidonic Acid; C068314:6-(bromomethylene)tetrahydro-3-(1-naphthaleneyl)-2H-pyran-2-one; D003513:Cycloheximide; D011065:Poly(ADP-ribose) Polymerases; D010741:Phospholipases A; D054522:Group VI Phospholipases A2; D054467:Phospholipases A2; D020169:Caspases; D019311:Staurosporine