CD14-dependent internalization and metabolism of extracellular phosphatidylinositol by monocytes.
We report that membrane CD14 (mCD14), a cell surface receptor found principally on leukocytes, can mediate the uptake and metabolism of extracellular phosphatidylinositol (PtdIns). mCD14 facilitates PtdIns internalization, targeting it to intracellular sites where, following stimulation with a calcium ionophore, it can be acted upon by cytosolic phospholipase A(2). The [(14)C]arachidonate released from mCD14-acquired [(14)C]arachidonyl-PtdIns is either esterified to triacylglycerol and retained in the cell or secreted as free arachidonate or leukotrienes. Although less than 10% of the arachidonate-derived lipids secreted from endogenous cellular stores are 5-lipoxygenase metabolites, over one-half of the secreted (14)C-lipids derived from mCD14-acquired PtdIns are hydroxyeicosatetraenoic acids or leukotriene B(4). mCD14 may allow these highly active blood cells to acquire and use extracellular PtdIns as a source of arachidonate for leukotriene synthesis.
Wang
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PY
Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas 75235-9113, USA.
Munford
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RS
D016718:Arachidonic Acid / Q000378:metabolism; D002460:Cell Line; D004705:Endocytosis; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000378:metabolism*; D009000:Monocytes / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism*
D018950:Lipopolysaccharide Receptors; D010716:Phosphatidylinositols; D016718:Arachidonic Acid