title: Regulation of phospholipid scramblase activity during apoptosis and cell activation by protein kinase Cdelta.
abstract: Phospholipid scramblase induces nonspecific bidirectional movement of phospholipids across the membrane during cell activation and has been proposed to mediate the appearance of phosphatidylserine (PS) in the plasma membrane outer leaflet during apoptosis, a cell surface change that is critical for apoptotic cell removal. We report here that protein kinase C (PKC) delta plays an important role in activated transbilayer movement of phospholipids and surface PS exposure by directly enhancing the activity of phospholipid scramblase. Specific inhibition of PKCdelta by rottlerin prevented both apoptosis- and activation-induced scramblase activity. PKCdelta was either selectively cleaved and activated in a caspase 3-dependent manner (during apoptosis) or translocated to the plasma membrane (in stimulated cells) and could directly phosphorylate scramblase immunoprecipitated from Jurkat cells. Furthermore, reconstitution of PKCdelta and scramblase, but not scramblase or PKCdelta alone in Chinese hamster ovary cells demonstrated enhanced scramblase activity.
authors.affiliation: Department of Pediatrics, National Jewish Medical and Research Center, Denver, Colorado 80206, USA. fraschc@njc.org
authors.forename: S C
authors.initials: SC
authors.lastname: Frasch
authors.forename: P M
authors.initials: PM
authors.lastname: Henson
authors.forename: J M
authors.initials: JM
authors.lastname: Kailey
authors.forename: D A
authors.initials: DA
authors.lastname: Richter
authors.forename: M S
authors.initials: MS
authors.lastname: Janes
authors.forename: V A
authors.initials: VA
authors.lastname: Fadok
authors.forename: D L
authors.initials: DL
authors.lastname: Bratton
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D016466:CHO Cells; D002352:Carrier Proteins / Q000378:metabolism*; D006224:Cricetinae; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D019169:Jurkat Cells; D008051:Lipid Bilayers; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D049294:Phospholipid Transfer Proteins; D011493:Protein Kinase C / Q000378:metabolism*; D051745:Protein Kinase C-delta; D014162:Transfection
chemical_list: D002352:Carrier Proteins; D007527:Isoenzymes; D008051:Lipid Bilayers; D008565:Membrane Proteins; D049294:Phospholipid Transfer Proteins; C497258:PRKCD protein, human; D011493:Protein Kinase C; D051745:Protein Kinase C-delta