title: Ca2(+)-dependence of arachidonic acid redistribution among phospholipids of cultured mouse keratinocytes.
abstract: Mouse keratinocytes cultured in a medium containing less than 0.1 mM Ca2+ (low Ca2+) incorporated [1-14C]arachidonic acid (AA) into phospholipids by kinetics including; (i) a rapid labelling of phosphatidylinositol (PtdIns), phosphatidylserine (PtdSer) and both acid-stable and alkenylacyl forms of phosphatidylcholine (PtdCho); and (ii) a slow but long-lasting radiolabel incorporation into both acid-stable and alkenylacyl forms of phosphatidylethanolamine (PtdEtn), partly associated with a net radioactivity loss from acid stable-PtdCho. Under low Ca2+ conditions no radioactivity transfer apparently occurred between PtdIns and other phospholipid classes. When cells were prelabelled for 24 h with [1-14C]AA and reincubated in label-free medium containing 1.2 mM Ca2+ (normal Ca2+), an early and extensive loss of radioactivity from PtdIns was observed, reasonably in connection with Ca2+ stimulation of phosphoinositide turnover. Cell shift to normal Ca2+ did not result in an increased synthesis of labelled eicosanoids, but was consistent with an increase of radioactivity incorporation into diacylglycerol (DAG) and with a complex pattern of [1-14C]AA redistribution, eventually leading to a marked radioactivity incorporation into acid stable-PtdEtn (but not into alkenylacyl-PtdEtn) and to a labelling decrease of acid stable-PtdCho. The possible mechanisms driving AA recycling after cell shift to normal Ca2+ are discussed.
authors.affiliation: Department of Biology, University of Rome Tor Vergata, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Pacini
authors.forename: A
authors.initials: A
authors.lastname: Spinedi
authors.forename: M
authors.initials: M
authors.lastname: Piacentini
authors.forename: C
authors.initials: C
authors.lastname: Limatola
authors.forename: M G
authors.initials: MG
authors.lastname: Farrace
authors.forename: F
authors.initials: F
authors.lastname: Autuori
authors.forename: P
authors.initials: P
authors.lastname: Luly
mesh_terms: D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D015603:Keratinocytes / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D010713:Phosphatidylcholines / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism; D010718:Phosphatidylserines / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism*; D013997:Time Factors
chemical_list: D001095:Arachidonic Acids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010718:Phosphatidylserines; D010743:Phospholipids; D016718:Arachidonic Acid; D002118:Calcium