Examination of the Rac-modulator ArhGAP15 in platelet activation.

Objective Platelet activation is triggered by various stimuli engaging with surface expressed receptors. Intracellular signaling then leads to the shape change, granule secretion and integrin activation in platelets. One key component of integrin activation in various hematopoietic cells is Rac and Rac-modulating proteins. The de-activating Rac-modulator ArhGAP15 has been shown to control leukocyte functionality in vivo, but little is known about its role in platelets. We thus set out to determine whether ArhGAP15 is expressed in platelets and how deficiency of ArhGAP15 affects platelet functionality.

Material and Methods For this purpose, we removed and washed citrate-anticoagulated whole blood from wildtype and ArhGAP15 deficient mice. Following, samples were incubated with different stimuli (thrombin, ADP, collagen), labelled with antibodies against GpIb in order to determine the platelet population, P-selectin and the activated conformation for the integrin GpIIb/IIIa and activation measured by flow cytometry. A model of mesenteric ferric chloride induced thrombus formation was used to assess in vivo relevance of ArhGAP15-deficiency.

Results Expression of ArhGAP15 in murine platelets was verified by western blot. Flow cytometry-based platelet activation assays revealed no significant difference for thrombin, ADP and collagen stimulation of washed murine wildtype and ArhGAP15 deficient platelets in vitro. In a model of ferric chloride induced rapid thrombus formation, no significant difference was observed between wildtype and ArhGAP15 deficient animals.

Conclusion Lack of the Rac-modulator ArhGAP15 does not impair the classical inside-out activation responses of murine platelets.

Publication History

Article published online:
18 June 2021