Communication Dans Un Congrès Année : 2025

A novel β1-tubulin mutation associated with secretion-dependent platelet hyperactivity and prothrombotic risk via GPVI and CLEC-2 engagement

Résumé

Background While mutations in β1-tubulin (TUBB1) have previously been linked to macrothrombocytopenia, their effect on platelet function remains poorly understood. We previously identified a novel TUBB1 mutation, p.P160L, associated with thyroid dysgenesis, macroplatelets, and platelet hyperactivation (Stoupa A et al. EMBO Mol Med. 2018). Aim To investigate the impact of the TUBB1 p.P160L mutation on platelet morphology and function. Methods A knock-in mouse model harboring the Tubb1 p.P160L mutation was used to evaluate the hemostatic phenotype in vivo and in vitro. Wild-type (WT), heterozygous (HET), and homozygous (KI) mice were compared. Results Morphological abnormalities and microtubule disorganization: Platelet counts were normal in HET and KI mice, but platelet size was increased. Electron microscopy revealed rounded platelets with disorganized microtubule structures. Microtubule sedimentation assays showed reduced TUBB1 incorporation into microtubules, suggesting that Tubb1 p.P160L mutation impairs microtubule organization and platelet structure. Enhanced platelet activation dependent on increased RhoA activity: Flow cytometry analysis revealed increased activation of integrin αIIbβ3 in response to convulxin and rhodocytin, while responses to ADP and thrombin were unchanged. Inhibition of ADP and thromboxane A2 amplification pathways normalized integrin activation. P-selectin exposure was also elevated in response to convulxin and rhodocytin. RhoA activity was increased after rhodocytin activation in KI platelets. These results suggest that enhanced GPVI- and CLEC-2-dependent activation and secretion in p.P160L platelets were dependent on increased RhoA activity. Prothrombotic phenotype: Under arterial flow conditions in a collagen-coated perfusion chamber, thrombi formed by HET and KI mice were larger than those from WT. This phenotype was reversed by inhibition of ADP and thromboxane A2. Additionally, in an in vivo thrombosis model, arteriolar occlusion time was shortened in HET and KI mice, indicating a prothrombotic tendency. Summary This study demonstrates for the first time that a mutation in TUBB1 disrupts microtubule organization and promotes secretion-dependent platelet hyperactivation via GPVI and CLEC-2 pathways, driven by increased RhoA activity. This results in a heightened thrombotic risk, revealing a novel functional consequence of TUBB1 mutations.

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inserm-05293799 , version 1 (02-10-2025)

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  • HAL Id : inserm-05293799 , version 1

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Toscane Viellard, Jean Solarz, Christelle Repérant, Christelle Soukaseum, Johannes A Eble, et al.. A novel β1-tubulin mutation associated with secretion-dependent platelet hyperactivity and prothrombotic risk via GPVI and CLEC-2 engagement. 7th EUPLAN International Conference, Sep 2025, Wuerzburg, Germany. ⟨inserm-05293799⟩
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