@article{NavarroStarkeHeemskerketal.2022, author = {Navarro, Stefano and Starke, Andreas and Heemskerk, Johan W. M. and Kuijpers, Marijke J. E. and Stegner, David and Nieswandt, Bernhard}, title = {Targeting of a conserved epitope in mouse and human GPVI differently affects receptor function}, series = {International Journal of Molecular Sciences}, volume = {23}, journal = {International Journal of Molecular Sciences}, number = {15}, issn = {1422-0067}, doi = {10.3390/ijms23158610}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-286227}, year = {2022}, abstract = {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.}, language = {en} } @article{PoppThielmanNieswandtetal.2015, author = {Popp, Michael and Thielman, Ina and Nieswandt, Bernhard and Stegner, David}, title = {Normal Platelet Integrin Function in Mice Lacking Hydrogen Peroxide-Induced Clone-5 (Hic-5)}, series = {PLoS One}, volume = {10}, journal = {PLoS One}, number = {7}, doi = {10.1371/journal.pone.0133429}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-125724}, pages = {e0133429}, year = {2015}, abstract = {Integrin αIIbβ3 plays a central role in the adhesion and aggregation of platelets and thus is essential for hemostasis and thrombosis. Integrin activation requires the transmission of a signal from the small cytoplasmic tails of the α or β subunit to the large extracellular domains resulting in conformational changes of the extracellular domains to enable ligand binding. Hydrogen peroxide-inducible clone-5 (Hic-5), a member of the paxillin family, serves as a focal adhesion adaptor protein associated with αIIbβ3 at its cytoplasmic tails. Previous studies suggested Hic-5 as a novel regulator of integrin αIIbβ3 activation and platelet aggregation in mice. To assess this in more detail, we generated Hic-5-null mice and analyzed activation and aggregation of their platelets in vitro and in vivo. Surprisingly, lack of Hic-5 had no detectable effect on platelet integrin activation and function in vitro and in vivo under all tested conditions. These results indicate that Hic-5 is dispensable for integrin αIIbβ3 activation and consequently for arterial thrombosis and hemostasis in mice.}, language = {en} }