Cloning and Expression of Two Human Lysophosphatidic Acid Acyltransferase cDNAs That Enhance Cytokine-Induced Signaling Responses in Cells

Lysophosphatidic acid (LPA) and phosphatidic acid (PA) are two phospholipids involved in signal transduction and in lipid biosynthesis in cells. LPA acyltransferase (LPAAT), also known as 1-acyl sn-glycerol-3-phosphate acetyltransferase (EC 2.3.1.51), catalyzes the conversion of LPA to PA. In this study, we describe the isolation and characterization of two human cDNAs that encode proteins possessing LPAAT activities. These two proteins, designated here as LPAAT-α and LPAAT-β, contain extensive sequence sequence similarities to microbial or plant LPAAT sequences. LPAAT-α mRNA was detected in all tissues with highest expression in skeletal muscle whereas LPAAT-β was expressed predominantly in heart and liver tissues. Expression of these two cDNAs in an Escherichia coli strain with a mutated LPAAT gene (plsC) complements its growth defect and shifts the equilibrium of cellular lipid content from LPA to PA and other lipids. Overexpression of these two cDNAs in mammalian cells leads to increased LPAAT activit...