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Please use this identifier to cite or link to this item: http://hdl.handle.net/2262/41144

Title: Dissociation of activated protein C functions by elimination of protein S cofactor enhancement.
Author: HARMON, SHONA
PRESTON, ROGER
O'DONNELL, JAMES
NI AINLE, FIONNUALA
JOHNSON, JENNIFER
Sponsor: Health Research Board
Author's Homepage: http://people.tcd.ie/prestonr
http://people.tcd.ie/sharmon
http://people.tcd.ie/jodonne
http://people.tcd.ie/niainlf
http://people.tcd.ie/johnsoje
Keywords: Clinical medicine
Hematology
anticoagulant function
Issue Date: 2008
Publisher: American Society for Biochemistry and Molecular Biology
Citation: Harmon, S, Preston, RJ, Ainle, FN, Johnson, JA, Cunningham, MS, Smith, OP, White, B, O'Donnell, JS, Dissociation of activated protein C functions by elimination of protein S cofactor enhancement., The Journal of Biological Chemistry, 283, 45, 2008, 30531 - 30539
Series/Report no.: The Journal of Biological Chemistry;
283;
45;
Abstract: Activated protein C (APC) plays a critical anticoagulant role in vivo by inactivating procoagulant factor Va and factor VIIIa and thus down-regulating thrombin generation. In addition, APC bound to the endothelial cell protein C receptor can initiate protease-activated receptor-1 (PAR-1)-mediated cytoprotective signaling. Protein S constitutes a critical cofactor for the anticoagulant function of APC but is not known to be involved in regulating APC-mediated protective PAR-1 signaling. In this study we utilized a site-directed mutagenesis strategy to characterize a putative protein S binding region within the APC Gla domain. Three single amino acid substitutions within the APC Gla domain (D35T, D36A, and A39V) were found to mildly impair protein S-dependent anticoagulant activity (<2-fold) but retained entirely normal cytoprotective activity. However, a single amino acid substitution (L38D) ablated the ability of protein S to function as a cofactor for this APC variant. Consequently, in assays of protein S-dependent factor Va proteolysis using purified proteins or in the plasma milieu, APC-L38D variant exhibited minimal residual anticoagulant activity compared with wild type APC. Despite the location of Leu-38 in the Gla domain, APC-L38D interacted normally with endothelial cell protein C receptor and retained its ability to trigger PAR-1 mediated cytoprotective signaling in a manner indistinguishable from that of wild type APC. Consequently, elimination of protein S cofactor enhancement of APC anticoagulant function represents a novel and effective strategy by which to separate the anticoagulant and cytoprotective functions of APC for potential therapeutic gain.
Description: PUBLISHED
URI: http://hdl.handle.net/2262/41144
Related links: http://dx.doi.org/10.1074/jbc.M802338200
Appears in Collections:Haematology (Scholarly Publications)

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