TY  - JOUR
A1  - Navarro, Stefano
A1  - Stegner, David
A1  - Nieswandt, Bernhard
A1  - Heemskerk, Johan W. M.
A1  - Kuijpers, Marijke J. E.
T1  - Temporal roles of platelet and coagulation pathways in collagen- and tissue factor-induced thrombus formation
JF  - International Journal of Molecular Sciences
N2  - In hemostasis and thrombosis, the complex process of thrombus formation involves different molecular pathways of platelet and coagulation activation. These pathways are considered as operating together at the same time, but this has not been investigated. The objective of our study was to elucidate the time-dependency of key pathways of thrombus and clot formation, initiated by collagen and tissue factor surfaces, where coagulation is triggered via the extrinsic route. Therefore, we adapted a microfluidics whole-blood assay with the Maastricht flow chamber to acutely block molecular pathways by pharmacological intervention at desired time points. Application of the technique revealed crucial roles of glycoprotein VI (GPVI)-induced platelet signaling via Syk kinase as well as factor VIIa-induced thrombin generation, which were confined to the first minutes of thrombus buildup. A novel anti-GPVI Fab EMF-1 was used for this purpose. In addition, platelet activation with the protease-activating receptors 1/4 (PAR1/4) and integrin αIIbβ3 appeared to be prolongedly active and extended to later stages of thrombus and clot formation. This work thereby revealed a more persistent contribution of thrombin receptor-induced platelet activation than of collagen receptor-induced platelet activation to the thrombotic process.
KW  - coagulation
KW  - fibrin
KW  - glycoprotein VI
KW  - platelet receptors
KW  - spatiotemporal thrombus
KW  - thrombin
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-284219
SN  - 1422-0067
VL  - 23
IS  - 1
ER  - 
TY  - JOUR
A1  - Navarro, Stefano
A1  - Starke, Andreas
A1  - Heemskerk, Johan W. M.
A1  - Kuijpers, Marijke J. E.
A1  - Stegner, David
A1  - Nieswandt, Bernhard
T1  - Targeting of a conserved epitope in mouse and human GPVI differently affects receptor function
JF  - International Journal of Molecular Sciences
N2  - Glycoprotein (GP) VI is the major platelet collagen receptor and a promising anti-thrombotic target. This was first demonstrated in mice using the rat monoclonal antibody JAQ1, which completely blocks the Collagen-Related Peptide (CRP)-binding site on mouse GPVI and efficiently inhibits mouse platelet adhesion, activation and aggregation on collagen. Here, we show for the first time that JAQ1 cross-reacts with human GPVI (huGPVI), but not with GPVI in other tested species, including rat, rabbit, guinea pig, swine, and dog. We further demonstrate that JAQ1 differently modulates mouse and human GPVI function. Similar to its effects on mouse GPVI (mGPVI), JAQ1 inhibits CRP-induced activation in human platelets, whereas, in stark contrast to mouse GPVI, it does not inhibit the adhesion, activation or aggregate formation of human platelets on collagen, but causes instead an increased response. This effect was also seen with platelets from newly generated human GPVI knockin mice (hGP6\(^{tg/tg\)). These results indicate that the binding of JAQ1 to a structurally conserved epitope in GPVI differently affects its function in human and mouse platelets.
KW  - glycoprotein VI
KW  - JAQ1
KW  - platelet receptors
KW  - platelet activation
KW  - platelet inhibition
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-286227
SN  - 1422-0067
VL  - 23
IS  - 15
ER  -