Protective Signaling by Activated Protein C Is Mechanistically Linked to Protein C Activation on Endothelial Cells

Feistritzer, Clemens; Schuepbach, Reto A.; Mosnier, Laurent O.; Bush, Leslie A.; Di, Enrico; Griffin, John H.; Riewald, Matthias

doi:10.1074/jbc.m600506200

Cited by 120 publications

(113 citation statements)

References 44 publications

Supporting

Mentioning

109

Contrasting

Order By: Relevance

“…Because thrombin is responsible for the activation of protein C and it also cleaves PAR-1 with a catalytic efficiency that is 3-4 orders of magnitude higher than that of APC, whether APC in the presence of thrombin produces physiologically significant protective signaling events by PAR-1 cleavage is controversial (14). Nevertheless, an interesting recent study demonstrated that the endogenous APC, generated by thrombin on the endothelial cell surface, exhibits much greater cellular effects than exogenous APC, suggesting that the activation of protein C on the cell surface may be mechanistically linked to its PAR-1-dependent protective signaling mechanism (16). Noting that APC and protein C both interact with EPCR with a similar affinity, Feistritzer et al (16) hypothesized that thrombin can increase the local concentrations of EPCR-bound APC, thus channeling the protease directly into the signaling pathway.…”

Section: Discussionmentioning

confidence: 99%

“…Nevertheless, an interesting recent study demonstrated that the endogenous APC, generated by thrombin on the endothelial cell surface, exhibits much greater cellular effects than exogenous APC, suggesting that the activation of protein C on the cell surface may be mechanistically linked to its PAR-1-dependent protective signaling mechanism (16). Noting that APC and protein C both interact with EPCR with a similar affinity, Feistritzer et al (16) hypothesized that thrombin can increase the local concentrations of EPCR-bound APC, thus channeling the protease directly into the signaling pathway. The findings of the present study, that all three receptors involved in both protein C activation and APC signaling are colocalized in the lipid rafts, explain how thrombin effectively channels endogenous APC to the protective signaling pathways.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, because both protein C and APC can interact with EPCR with a similar affinity of Ϸ30 nM (15), it is not readily clear how physiological concentrations of APC (Ͻ10 nM) can compete with the zymogen protein C (Ϸ80 nM) for binding to EPCR to exert its protective cellular effects. A partial answer to this question was recently provided by the observation that the cytoprotective activity of the endogenous APC generated by the thrombin-thrombomodulin (TM) complex is significantly higher than that of the exogenous APC, suggesting that endogenous protein C activation by thrombin is linked to efficient PAR-1-dependent protective signaling events in endothelial cells (16). One possible explanation of why the endogenous APC can exert a more efficient cytoprotective effect in endothelial cells might be that protein C zymogen activation by the thrombin-TM complex and the subsequent PAR-1 signaling events take place in the same microenvironment on the membrane surface.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Receptors of the protein C activation and activated protein C signaling pathways are colocalized in lipid rafts of endothelial cells

Bae

Yang

Rezaie

2007

Proc. Natl. Acad. Sci. U.S.A.

174

212

View full text Add to dashboard Cite

Ever-increasing evidence in the literature suggests that the antiinflammatory and cytoprotective properties of activated protein C (APC) are mediated through its endothelial protein C receptor (EPCR)-dependent cleavage of protease-activated receptor 1 (PAR-1) on endothelial cells. However, recent results monitoring the cleavage rate of PAR-1 on human umbilical vein endothelial cells, transfected with an alkaline phosphatase-PAR-1 fusion reporter construct, have indicated that the catalytic activity of thrombin toward PAR-1 is several orders of magnitude higher than that of APC. Because thrombin is required for generation of APC, and because it also functions in the proinflammatory pathways through the activation of PAR-1, it has been difficult to understand how APC can elicit protective cellular responses through the activation of PAR-1 when thrombin is present. In this study we provide a plausible answer to this question by demonstrating that the critical receptors required for both protein C activation (thrombomodulin and EPCR) and APC cellular signaling (EPCR and PAR-1) pathways are colocalized in the membrane lipid rafts in endothelial cells. We further show that the APC cleavage of PAR-1 on cells transfected with a PAR-1 cleavage reporter construct is not sensitive to the cofactor function of EPCR. Thus, the colocalization of EPCR and PAR-1 in lipid rafts is a key requirement for the cellular signaling activity of APC. Thrombomodulin colocalization with these receptors on the same membrane microdomain can also recruit thrombin to activate the EPCR-bound protein C, thereby eliciting PAR-1 signaling events that are involved in the APC protective pathways. endothelial protein C receptor ͉ protease-activated receptor 1 ͉ thrombin ͉ thrombomodulin

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Receptors of the protein C activation and activated protein C signaling pathways are colocalized in lipid rafts of endothelial cells

Bae

Yang

Rezaie

2007

Proc. Natl. Acad. Sci. U.S.A.

174

212

View full text Add to dashboard Cite

show abstract

“…Unlike the other family members, PAR-2 is not cleaved/activated by thrombin, but it can be activated through canonical cleavage by APC (43). Activation of PARs is closely regulated by EPCR and TM, increased concentrations of which favor endogenous protein C activation by TM-bound thrombin and subsequent proteolysis of PARs and other substrates by APC (44). We found that chondrocyte expression of EPCR and TM was induced by IL-1␣ and TNF␣, both of which are implicated in cartilage degradation in OA (45).…”

Section: Discussionmentioning

confidence: 99%

Activation of cartilage matrix metalloproteinases by activated protein C

Jackson

Smith

et al. 2009

Arthritis & Rheumatism

View full text Add to dashboard Cite

Objective. To investigate the role of activated protein C (APC) in cartilage degradation.Methods. Chondrocyte expression of protein C, endothelial protein C receptor (EPCR), and thrombomodulin (TM) were evaluated by reverse transcriptionpolymerase chain reaction (RT-PCR). APC was immunolocalized in developing joints and in osteoarthritic (OA) cartilage from humans. The effect of APC on aggrecan and collagen degradation was examined in explant cultures of ovine cartilage in control cultures and in cultures stimulated with interleukin-1␣ (IL-1␣), tumor necrosis factor ␣ (TNF␣), or retinoic acid (RetA), using colorimetric assays and Western blotting. Chondrocyte expression of matrix metalloproteinases (MMPs), ADAMTS, and tissue inhibitor of metalloproteinases (TIMPs) was measured by RT-PCR. MMP-2 and MMP-9 activity was evaluated by gelatin zymography and MMP-13 by fluorogenic assay.Results. Positive cellular immunostaining for APC was found at sites of MMP activity in developing joints and in OA, but not normal, cartilage. Chondrocytes expressed messenger RNA for protein C, EPCR, and TM, with the latter 2 levels increased by IL-1␣ and TNF␣ stimulation. APC augmented aggrecan release and initiated collagen breakdown in IL-1␣-treated and TNF␣-treated cartilage, but not in normal or in RetAtreated cartilage. APC-stimulated aggrecan and collagen breakdown were due to MMP activity but were not associated with modulation of MMP, ADAMTS, or TIMP expression. APC resulted in MMP-13 activation in cartilage cultures. APC could not directly activate proMMP-13, but it was associated with increased MMP-2 and MMP-9 activity.Conclusion. APC may be a relevant activator of MMPs in cartilage and may play a role in progressive cartilage degradation in arthritis.

show abstract

“…The apparent affinities for functionally relevant interactions of coagulation factors with EPCR are therefore difficult to predict solely based on measured affinities of individual components. For example, thrombin-thrombomodulin-mediated activation of EPCR-bound PC results in highly efficient EPCR-aPC-PAR1 signaling at a much lower concentration of aPC as compared with reactions to which aPC is added directly (20). Signaling of the ternary TF-FVIIa-FXa coagulation activation complex also occurs at lower concentrations of FXa when compared with reactions directly initiated by the addition of FXa (21,22).…”

mentioning

confidence: 99%

The Endothelial Protein C Receptor Supports Tissue Factor Ternary Coagulation Initiation Complex Signaling through Protease-activated Receptors

Disse

Petersen

Larsen

et al. 2011

Journal of Biological Chemistry

125

View full text Add to dashboard Cite

Protective Signaling by Activated Protein C Is Mechanistically Linked to Protein C Activation on Endothelial Cells

Cited by 120 publications

References 44 publications

Receptors of the protein C activation and activated protein C signaling pathways are colocalized in lipid rafts of endothelial cells

Receptors of the protein C activation and activated protein C signaling pathways are colocalized in lipid rafts of endothelial cells

Activation of cartilage matrix metalloproteinases by activated protein C

The Endothelial Protein C Receptor Supports Tissue Factor Ternary Coagulation Initiation Complex Signaling through Protease-activated Receptors

Contact Info

Product

Resources

About