Phosphorylation of Lysophosphatidylcholine Acyltransferase 2 at Ser34 Enhances Platelet-activating Factor Production in Endotoxin-stimulated Macrophages

• Published in: The Journal of biological chemistry Vol. 285; no. 39; pp. 29857 - 29862
• Main Authors: Morimoto, Ryo, Shindou, Hideo, Oda, Yoshiya, Shimizu, Takao
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 24.09.2010; American Society for Biochemistry and Molecular Biology
• Subjects: 1-Acylglycerophosphocholine O-Acyltransferase - biosynthesis; 1-Acylglycerophosphocholine O-Acyltransferase - genetics; Acyltransferase; Animals; Cells, Cultured; Enzymology; Gene Expression Regulation, Enzymologic - drug effects; Inflammation; Innate Immunity; Intracellular Signaling Peptides and Proteins - genetics; Intracellular Signaling Peptides and Proteins - metabolism; Lipids; Lipopolysaccharides - pharmacology; Lyso-PAF Acetyltransferase; Macrophages, Peritoneal - metabolism; MAP Kinase Signaling System - drug effects; Mice; MK2; Mutagenesis; Phosphatidylcholine; Phospholipid; Phospholipid Turnover; Phosphorylation; Phosphorylation - drug effects; Platelet Activating Factor - biosynthesis; Platelet Activating Factor - genetics; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Toll-Like Receptor 4 - genetics; Toll-Like Receptor 4 - metabolism; Lyso-PAF Acetyltransferase; Phosphorylation; MK2; Innate Immunity; Phosphatidylcholine; Phospholipid; Inflammation; Phospholipid Turnover; Acyltransferase
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M110.147025

Platelet-activating factor (PAF) is a potent proinflammatory phospholipid mediator that elicits various cellular functions under physiological and pathological conditions. We have recently identified two enzymes involved in PAF production: lysophosphatidylcholine acyltransferase-1 (LPCAT1) and LPCAT2. We found that LPCAT2 is highly expressed in inflammatory cells and is activated by lipopolysaccharide (LPS) treatment through Toll-like receptor 4. However, the molecular mechanism for the activation remains elusive. In this study, Phos-tag SDS-PAGE revealed the LPS-induced phosphorylation of LPCAT2. Furthermore, mass spectrometry and mutagenesis analyses identified Ser34 of LPCAT2 as the phosphorylation site to enhance the catalytic activities. The experiments using inhibitors and siRNA against MAPK cascades demonstrated that LPCAT2 phosphorylation through LPS-TLR4 signaling may directly depend on MAPK-activated protein kinase 2 (MAPKAP kinase 2 or MK2). These findings develop a further understanding of both PAF production and phospholipid remodeling triggered by inflammatory stimuli. Specific inhibition of the PAF biosynthetic activity by phosphorylated LPCAT2 will provide a novel target for the regulation of inflammatory disorders.