Mitogen-activated protein kinase-mediated phosphorylation of peroxiredoxin 6 regulates its phospholipase A(2) activity.
Prdx6 (peroxiredoxin 6), a bifunctional protein with both GSH peroxidase and PLA(2) (phospholipase A(2)) [aiPLA(2) (acidic calcium-independent PLA(2))] activities, is responsible for the metabolism of lung surfactant phospholipids. We propose that the aiPLA(2) activity of the enzyme is regulated through phosphorylation. Incubation of isolated rat alveolar type II cells (AECII) with PMA, a PKC (protein kinase C) agonist, had no effect on Prdx6 expression but led to approximately 75% increase in aiPLA(2) activity that was abolished by pretreatment of cells with the MAPK (mitogen-activated protein kinase) inhibitors, SB202190 or PD98059. Prdx6 phosphorylation after incubation of AECII with PMA was demonstrated by autoradiography after immunoprecipitation with either anti-phosphothreonine o-phosphoserine antibodies. in vitro, several active isoforms of ERK (extracellular-signal-regulated kinase) and p38 phosphorylated Prdx6, resulting in an 11-fold increase in aiPLA(2) activity. The increased activity was calcium-independent and was abolished by the aiPLA(2) inhibitors, surfactant protein A and hexadecyl-3-trifluorethylglycero-sn-2-phospho-methanol (MJ33). The peroxidase activity of Prdx6 was unaffected by phosphorylation. Mass spectroscopic analysis of in vitro phosphorylated Prdx6 showed a unique phosphorylation site at Thr-177 and mutation of this residue abolished protein phosphorylation and the increase in MAPK-mediated activity. These results show that the MAPKs can mediate phosphorylation of Prdx6 at Thr-177 with a consequent marked increase in its aiPLA(2) activity.
Wu
Yongzheng
Y
Institute for Environmental Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6068, U.S.A.
Feinstein
Sheldon I
SI
Manevich
Yefim
Y
Chowdhury
Ibrul
I
Pak
Jhang Ho
JH
Kazi
Altaf
A
Dodia
Chandra
C
Speicher
David W
DW
Fisher
Aron B
AB
D000818:Animals; D002457:Cell Extracts; D015180:Electrophoresis, Gel, Two-Dimensional; D004705:Endocytosis / Q000187:drug effects; D006801:Humans; D047468:Immunoprecipitation; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D054465:Peroxiredoxin VI / Q000378:metabolism*; D054467:Phospholipases A2 / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011650:Pulmonary Alveoli / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013912:Threonine / Q000378:metabolism
D002457:Cell Extracts; D047428:Protein Kinase Inhibitors; D013912:Threonine; D054465:Peroxiredoxin VI; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D054467:Phospholipases A2; D013755:Tetradecanoylphorbol Acetate