Dataset Information

Quantitative phosphoproteomics unveils temporal dynamics of thrombin signaling in human endothelial cells

ABSTRACT: Thrombin is the key serine protease of the coagulation cascade and a potent trigger of protease-activated receptor (PAR)1-mediated platelet aggregation. In recent years, PAR1 has become an appealing target for anticoagulant therapies. However, the inhibitors that have been developed so far increase bleeding risk in patients, likely because they interfere with endogenous PAR1 signaling in the endothelium. Due to its complexity, thrombin-induced signaling in endothelial cells has remained incompletely understood. Here, we have combined stable isotope amino acids in cell culture, affinity-based phospho-peptide enrichment and high resolution mass spectrometry and performed a time-resolved analysis of the thrombin-induced signaling in human primary endothelial cells. We identified 2224 thrombin-regulated phosphorylation sites, the majority of which has not been previously related to thrombin. Those sites were localized on proteins which are novel to thrombin signaling, but also on well-known players such as PAR1, Rho-associated kinase 2, phospholipase C, and proteins related to actin cytoskeleton, cell-cell junctions and Weibel-Palade body release. Our study provides a unique resource of phosphoproteins and phosphorylation sites which may generate novel insights into an intimate understanding of thrombin-mediated PAR signaling and the development of improved PAR1 antagonists that affect platelet but not endothelial cell function.

REANALYSED by: PAe005425

INSTRUMENT(S): LTQ Orbitrap Elite

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Endothelial Cell, Blood

SUBMITTER: Sara Zanivan

LAB HEAD: Sara Zanivan

PROVIDER: PXD000597 | Pride | 2014-02-06

REPOSITORIES: Pride

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Quantitative phosphoproteomics unveils temporal dynamics of thrombin signaling in human endothelial cells.

van den Biggelaar Maartje M Hernández-Fernaud Juan Ramon JR van den Eshof Bart L BL Neilson Lisa J LJ Meijer Alexander B AB Mertens Koen K Zanivan Sara S

Blood 20140205 12

Thrombin is the key serine protease of the coagulation cascade and a potent trigger of protease-activated receptor 1 (PAR1)-mediated platelet aggregation. In recent years, PAR1 has become an appealing target for anticoagulant therapies. However, the inhibitors that have been developed so far increase bleeding risk in patients, likely because they interfere with endogenous PAR1 signaling in the endothelium. Because of its complexity, thrombin-induced signaling in endothelial cells has remained in ...[more]

PMID: 24501219

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Project description:Phosphoproteomic analysis of platelets activated by pro-thrombotic oxidized phospholipids and thrombin Alejandro Zimman, Bjoern Titz, Evangelia Komisopoulou, Sudipta Biswas, Thomas G. Graeber, and Eugene A. Podrez ABSTRACT Specific oxidized phospholipids (oxPCCD36) promote platelet hyper-reactivity and thrombosis in hyperlipidemia via the scavenger receptor CD36, however the signaling pathway(s) induced in platelets by oxPCCD36 are not well defined. We have now employed mass spectrometry-based tyrosine, serine, and threonine global phosphoproteomics for the unbiased analysis of platelet signaling pathways induced by oxPCCD36 as well as by the strong physiological agonist thrombin. oxPCCD36 and thrombin induced differential phosphorylation of 115 proteins (162 phosphorylation sites) and 181 proteins (334 phosphorylation sites) respectively. Most of the phosphoproteome changes induced by either agonist have never been reported in platelets; thus they provide a new resource to study platelet signaling. Bioinformatic analyses of protein phosphorylation dependent responses were used to categorize preferential motifs for (de)phosphorylation, predict pathways and kinase activity, and construct a phosphoproteome network regulating integrin activation. A putative signaling pathway involving Src-family kinases, SYK, and PLCy2 was identified in platelets activated by oxPCCD36. Subsequent ex vivo studies in human platelets demonstrated that this pathway is downstream of the scavenger receptor CD36 and is critical for platelet activation by oxPCCD36. Our results provide multiple novel insights into the mechanism of platelet activation and specifically in platelet regulation by oxPCCD36. Methods Human platelets isolated by gel filtration (2.7 x 108 / mL) were incubated in Tyrode's buffer with 50 uM KODA-PC or PLPC (as control) for 30 min at 37 degrees C. Platelets were then centrifuged at 3,700 g (10 min, 35 degrees C) and lysed in 8 M urea, 50 mM Tris-HCl (pH 7.4), 1 mM Na3VO4, and 1 mM NaF with sonication. Phosphoproteome changes induced by the agonists were assessed based on trypsin digestion of the protein lysate, phosphopeptide enrichment, mass spectrometry analysis, chromatography alignment, and label-free quantitation as described in the Supplemental Materials and Methods of the publication. The same protocol was applied when studying platelet activation by thrombin, where gel-filtered platelets were incubated in Tyrode's buffer with 0.05 U/mL thrombin or in buffer alone (Resting) for 3 min at 37 degrees C.

Project description:Cysteinyl leukotrienes (cysLT), i.e. LTC4, LTD4, and LTE4, are lipid mediators derived from the 5-lipoxygenase pathway. The cysLT receptors cysLT1-R and cysLT2-R are expressed on different target cells and mediate inflammatory reactions in tissue- and LT-R-specific ways. Though endothelial cells (ECs) predominantly express cysLT2-Rs, their role in vascular biology remains to be defined. To delineate cysLT2-R´s action, we stimulated human umbilical vein EC with 100 nM LTD4 for 60 min, determined gene signatures by microarrays, and characterized the resulting EC phenotypes. As controls, we compared LTD4-induced genes with those induced by 10 nM thrombin, a prototype vasoactive activator of EC that binds to protease-activated receptor 1 (PAR-1). Following application of stringent filters 37 LTD4-upregulated genes were identified (> 2.5fold stimulation). Surprisingly, most of the LTD4-regulated genes were also induced by thrombin and expression of cysLT2-R- and PAR-1-regulated genes strongly correlated (Pearson correlation coefficient: r = 0.90). Moreover, LTD4 + thrombin, when added together, augmented expression of LTD4- or thrombin-stimulated genes (Wilcoxon signed rank test: p < 0.01). Prominently induced genes that may play roles in vascular injury were studied in detail: Early growth response (EGR) and nuclear receptor subfamily 4 group A; E-selectin; CXC ligand 2; interleukin 8 (IL-8); a disintegrin-like and metalloprotease (reprolysin type) with thrombospondin type 1 motif 1 (ADAMTS-1); and tissue factor (TF). Transcripts of these genes peaked at approximately 60 min, were unaffected by the cysLT1-R antagonist montelukast, and were superinduced by cycloheximide. The EC phenotype was markedly altered: LTD4 induced de novo synthesis of EGR1 protein and EGR1 localized in the nucleus in LTD4-stimulated cells; LTD4 upregulated IL-8 formation and secretion; and LTD4 raised TF protein and TF-dependent EC pro-coagulant activity. These data show that cysLT2-R activation results in a pro-inflammatory EC phenotype through activation of immediate-early genes that resemble those induced by PAR-1. As LTD4 and thrombin are formed concomitantly during vascular injury and pro-thrombotic states, cysLT2-R and PAR-1 may collaborate in vivo to mediate vascular injury and repair. Keywords: Leukotriene Transcriptome, Thrombin Transcriptome, HUVEC, Immediate-Early Gene Expression, Cysteinyl Leukotriene 2 Receptor Gene Signature in HUVEC

Project description:Cysteinyl leukotrienes (cysLT), i.e. LTC4, LTD4, and LTE4, are lipid mediators derived from the 5-lipoxygenase pathway. The cysLT receptors cysLT1-R and cysLT2-R are expressed on different target cells and mediate inflammatory reactions in tissue- and LT-R-specific ways. Though endothelial cells (ECs) predominantly express cysLT2-Rs, their role in vascular biology remains to be defined. To delineate cysLT2-RÂ´s action, we stimulated human umbilical vein EC with 100 nM LTD4 for 60 min, determined gene signatures by microarrays, and characterized the resulting EC phenotypes. As controls, we compared LTD4-induced genes with those induced by 10 nM thrombin, a prototype vasoactive activator of EC that binds to protease-activated receptor 1 (PAR-1). Following application of stringent filters 37 LTD4-upregulated genes were identified (> 2.5fold stimulation). Surprisingly, most of the LTD4-regulated genes were also induced by thrombin and expression of cysLT2-R- and PAR-1-regulated genes strongly correlated (Pearson correlation coefficient: r = 0.90). Moreover, LTD4 + thrombin, when added together, augmented expression of LTD4- or thrombin-stimulated genes (Wilcoxon signed rank test: p < 0.01). Prominently induced genes that may play roles in vascular injury were studied in detail: Early growth response (EGR) and nuclear receptor subfamily 4 group A; E-selectin; CXC ligand 2; interleukin 8 (IL-8); a disintegrin-like and metalloprotease (reprolysin type) with thrombospondin type 1 motif 1 (ADAMTS-1); and tissue factor (TF). Transcripts of these genes peaked at approximately 60 min, were unaffected by the cysLT1-R antagonist montelukast, and were superinduced by cycloheximide. The EC phenotype was markedly altered: LTD4 induced de novo synthesis of EGR1 protein and EGR1 localized in the nucleus in LTD4-stimulated cells; LTD4 upregulated IL-8 formation and secretion; and LTD4 raised TF protein and TF-dependent EC pro-coagulant activity. These data show that cysLT2-R activation results in a pro-inflammatory EC phenotype through activation of immediate-early genes that resemble those induced by PAR-1. As LTD4 and thrombin are formed concomitantly during vascular injury and pro-thrombotic states, cysLT2-R and PAR-1 may collaborate in vivo to mediate vascular injury and repair. Experiment Overall Design: HUVEC in passage 1 were cultured in serum-free EC medium until cells reached confluency. HUVEC were stimulated by 100 nM LTD4 (n = 4) or 10 nM thrombin (n = 4) or both agonists concomitantly (n = 3). The immediate-early gene programs of these experimental groups were identified at 60 minutes. In addition, one HUVEC preparation was stimulated with 100 nM LTD4 for 6 h and 24 h.

Dataset Information

Quantitative phosphoproteomics unveils temporal dynamics of thrombin signaling in human endothelial cells

Publications

Quantitative phosphoproteomics unveils temporal dynamics of thrombin signaling in human endothelial cells.

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