title: Platelet senescence and phosphatidylserine exposure.
abstract: BACKGROUND
  The exposure of phosphatidylserine occurs during platelet (PLT) activation and during in vitro storage. Phosphatidylserine exposure also occurs during apoptosis after the release of mitochondrial cytochrome c. We have examined the role of cytochrome c release, mitochondrial membrane potential (ΔΨm), and cyclophilin D (CypD) in phosphatidylserine exposure due to activation and storage.
  
  
  METHODS
  The exposure of phosphatidylserine and the loss of ΔΨm were determined in a flow cytometer using fluorescein isothiocyanate-lactadherin and JC-1, a lipophilic cationic reporter dye. The role of CypD was determined with cyclosporin A and CypD-deficient murine PLTs. Cytochrome c-induced caspase-3 and Rho-associated kinase I (ROCK1) activation were determined by immunoblotting and using their inhibitors.
  
  
  RESULTS
  Collagen- and thrombin-induced exposure of phosphatidylserine was accompanied by a decrease in ΔΨm. Cyclosporin A inhibited the phosphatidylserine exposure and the loss of ΔΨm. CypD(-/-) mice had decreased loss of ΔΨm and impaired phosphatidylserine exposure. Collagen and thrombin did not induce the release of cytochrome c nor the activation of caspase-3 and ROCK1. In contrast, in PLTs stored for more than 5 days, the phosphatidylserine exposure was associated with cytochrome c-induced caspase-3 and ROCK1 activation. ABT737, a BH3 mimetic that induces mitochondrial pathway of apoptosis, induced cytochrome c release and activation of caspase-3 and ROCK1 and phosphatidylserine exposure independent of CypD.
  
  
  CONCLUSIONS
  These results show that in stored PLTs cytochrome c release and the subsequent activation of caspase-3 and ROCK1 mediate phosphatidylserine exposure and it is distinct from activation-induced phosphatidylserine exposure.
authors.affiliation: Michael E. DeBakey Veterans Affairs Medical Center, Department of Pathology, Baylor College of Medicine.
authors.forename: Swapan Kumar
authors.initials: SK
authors.lastname: Dasgupta
authors.forename: Eduardo Rios
authors.initials: ER
authors.lastname: Argaiz
authors.forename: Jose Emmanel Chedid
authors.initials: JE
authors.lastname: Mercado
authors.forename: Hector Omar Elizondo
authors.initials: HO
authors.lastname: Maul
authors.forename: Jorge
authors.initials: J
authors.lastname: Garza
authors.forename: Ana Bety
authors.initials: AB
authors.lastname: Enriquez
authors.forename: Hanan
authors.initials: H
authors.lastname: Abdel-Monem
authors.forename: Anthony
authors.initials: A
authors.lastname: Prakasam
authors.forename: Michael
authors.initials: M
authors.lastname: Andreeff
authors.forename: Perumal
authors.initials: P
authors.lastname: Thiagarajan
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D016922:Cellular Senescence / Q000187:drug effects* / Q000235:genetics; D000081406:Peptidyl-Prolyl Isomerase F; D021983:Cyclophilins / Q000235:genetics; D045304:Cytochromes c / Q000378:metabolism; D005434:Flow Cytometry; D051379:Mice; D018345:Mice, Knockout; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010718:Phosphatidylserines / Q000494:pharmacology*; D015539:Platelet Activation / Q000187:drug effects* / Q000235:genetics
chemical_list: D000081406:Peptidyl-Prolyl Isomerase F; C000631446:PPIF protein, mouse; D010718:Phosphatidylserines; D045304:Cytochromes c; D021983:Cyclophilins
references.citation: Nat Genet. 2008 Apr;40(4):387-9
references.pmid: 18345000
references.citation: J Biol Chem. 1991 Dec 25;266(36):24302-7
references.pmid: 1662206
references.citation: Pflugers Arch. 2007 Dec;455(3):375-96
references.pmid: 17611770
references.citation: Arterioscler Thromb Vasc Biol. 2005 Feb;25(2):467-71
references.pmid: 15591217
references.citation: Transfusion. 2000 Oct;40(10):1257-63
references.pmid: 11061865
references.citation: Transfusion. 2003 Apr;43(4):526-35
references.pmid: 12662287
references.citation: Nat Rev Immunol. 2007 Dec;7(12):964-74
references.pmid: 18037898
references.citation: Biochim Biophys Acta. 2008 Jul-Aug;1777(7-8):946-52
references.pmid: 18407825
references.citation: Blood. 2008 Feb 1;111(3):1257-65
references.pmid: 17989312
references.citation: Semin Thromb Hemost. 1992;18(3):311-23
references.pmid: 1455249
references.citation: Transfusion. 2004 Jan;44(1):131-3
references.pmid: 14692979
references.citation: Transfusion. 2003 Jul;43(7):857-66
references.pmid: 12823744
references.citation: Nat Rev Mol Cell Biol. 2003 Jun;4(6):446-56
references.pmid: 12778124
references.citation: Nature. 2005 Jun 2;435(7042):677-81
references.pmid: 15902208
references.citation: J Biol Chem. 1990 Oct 15;265(29):17420-3
references.pmid: 2145274
references.citation: Transfus Med Rev. 2007 Oct;21(4):287-94
references.pmid: 17900490
references.citation: J Thromb Haemost. 2004 Apr;2(4):651-9
references.pmid: 15102022
references.citation: Vox Sang. 1986;51(4):299-305
references.pmid: 3798864
references.citation: Transl Res. 2006 Jul;148(1):19-25
references.pmid: 16887494
references.citation: Nat Rev Cancer. 2009 May;9(5):321-6
references.pmid: 19343035
references.citation: J Cell Biol. 1998 Oct 5;143(1):217-24
references.pmid: 9763433
references.citation: Arterioscler Thromb Vasc Biol. 1999 Dec;19(12):2841-6
references.pmid: 10591659
references.citation: J Biol Chem. 1999 Oct 1;274(40):28293-300
references.pmid: 10497186
references.citation: Blood. 2009 Jul 16;114(3):663-6
references.pmid: 19387006
references.citation: Biochimie. 1998 Feb;80(2):173-95
references.pmid: 9587675
references.citation: Nature. 1997 Oct 30;389(6654):990-4
references.pmid: 9353125
references.citation: Biochim Biophys Acta. 1990 Jul 24;1026(2):153-60
references.pmid: 2116169
references.citation: Methods Mol Biol. 2008;477:89-97
references.pmid: 19082941
references.citation: Cell. 2007 Mar 23;128(6):1173-86
references.pmid: 17382885
references.citation: Cell Death Differ. 2007 May;14(5):943-51
references.pmid: 17205078
references.citation: Blood. 1985 Nov;66(5):1105-9
references.pmid: 4052629