Lagarrigue, Frederic 
ORCID: 0000-0002-4660-8666, Gingras, Alexandre R ORCID: 0000-0002-5373-0176, Paul, David S, Valadez, Andrew J, Cuevas, Monica N, Sun, Hao ORCID: 0000-0002-4790-8847, Lopez-Ramirez, Miguel A, Goult, Benjamin T ORCID: 0000-0002-3438-2807, Shattil, Sanford J, Bergmeier, Wolfgang et al (show 1 more authors)
(2018)
Rap1 binding to the talin 1 F0 domain makes a minimal contribution to murine platelet GPIIb-IIIa activation.
Blood advances, 2 (18).
pp. 2358-2368.
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Abstract
Activation of platelet glycoprotein IIb-IIIa (GPIIb-IIIa; integrin αIIbβ3) leads to high-affinity fibrinogen binding and platelet aggregation during hemostasis. Whereas GTP-bound Rap1 GTPase promotes talin 1 binding to the β3 cytoplasmic domain to activate platelet GPIIb-IIIa, the Rap1 effector that regulates talin association with β3 in platelets is unknown. Rap1 binding to the talin 1 F0 subdomain was proposed to forge the talin 1-Rap1 link in platelets. Here, we report a talin 1 point mutant (R35E) that significantly reduces Rap1 affinity without a significant effect on its structure or expression. Talin 1 head domain (THD) (R35E) was of similar potency to wild-type THD in activating αIIbβ3 in Chinese hamster ovary cells. Coexpression with activated Rap1b increased activation, and coexpression with Rap1GAP1 reduced activation caused by transfection of wild-type THD or THD(R35E). Furthermore, platelets from <i>Tln1</i><sup><i>R35E/R35E</i></sup> mice showed similar GPIIb-IIIa activation to those from wild-type littermates in response to multiple agonists. <i>Tln1</i><sup><i>R35E/R35E</i></sup> platelets exhibited slightly reduced platelet aggregation in response to low doses of agonists; however, there was not a significant hemostatic defect, as judged by tail bleeding times. Thus, the Rap1-talin 1 F0 interaction has little effect on platelet GPIIb-IIIa activation and hemostasis and cannot account for the dramatic effects of loss of Rap1 activity on these platelet functions.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | Blood Platelets, CHO Cells, Animals, Mice, Transgenic, Cricetulus, Mice, rap1 GTP-Binding Proteins, Talin, Platelet Glycoprotein GPIIb-IIIa Complex, Blood Cell Count, Platelet Function Tests, Protein Conformation, Mutation, Models, Molecular, Female, Male, Protein Interaction Domains and Motifs |
| Divisions: | Faculty of Health and Life Sciences Faculty of Health and Life Sciences > Institute of Systems, Molecular and Integrative Biology |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 13 Mar 2024 09:55 |
| Last Modified: | 13 Mar 2024 09:55 |
| DOI: | 10.1182/bloodadvances.2018020487 |
| Related URLs: | |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3179321 |
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