title: Production of bioactive lysophosphatidic acid by lysophospholipase D in hen egg white.
abstract: Lysophosphatidic acid (LPA), a lysophospholipid mediator, is produced extracellularly by lysophospholipase D (lysoPLD) secreted in several animal body fluids including blood plasma. Previously, we reported that hen egg white contains polyunsaturated fatty acid-rich LPA. In this study, we examined whether lysoPLD is involved in the production of LPA in hen egg white. LysoPLD activity was measured by determining LPA and choline by mass spectrometric and enzyme-linked fluorometric analyses, respectively. LysoPLD increased with increased dilution of egg white, indicating that one or more components of egg white strongly inhibit its lysoPLD activity. This dilution-dependent increase in the lysoPLD activity was masked by co-incubation of the egg white with lysozyme, a major protein in hen egg white. Furthermore, addition of Zn(2+), Mn(2+), Ni(2+), or Co(2+) to diluted egg white altered preference patterns of lysoPLD toward choline-containing substrates. In particular, the egg white lysoPLD activity was greatly increased when Co(2+) was added. The cation-requirement of lysoPLD activity in hen egg white resembled that of plasma autotaxin (ATX)/lysoPLD. Western blot analysis revealed that egg white contained a protein that was immunostained with anti-ATX antibody. These results suggested that LPA in hen egg white is produced from lysophospholipids, especially LPC, by the action of ATX/lysoPLD, possibly originating from hen oviduct fluid.
authors.affiliation: Laboratory of Health Chemistry, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan.
authors.forename: Junichi
authors.initials: J
authors.lastname: Morishige
authors.forename: Kanako
authors.initials: K
authors.lastname: Touchika
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Tanaka
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Satouchi
authors.forename: Kenji
authors.initials: K
authors.lastname: Fukuzawa
authors.forename: Akira
authors.initials: A
authors.lastname: Tokumura
mesh_terms: D000818:Animals; D030161:Avian Proteins / Q000378:metabolism; D002645:Chickens; D002794:Choline / Q000378:metabolism; D004529:Egg White / Q000737:chemistry*; D008246:Lysophospholipids / Q000096:biosynthesis*; D008670:Metals / Q000494:pharmacology; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D013379:Substrate Specificity / Q000187:drug effects; D000099189:Lysophospholipase D
chemical_list: D030161:Avian Proteins; D002794:Choline; D008246:Lysophospholipids; D008670:Metals; D010727:Phosphoric Diester Hydrolases; D000099189:Lysophospholipase D; C032881:lysophosphatidic acid