Blood Coagulation and Platelet Function Are Impaired By the ARP2 p.R258G Variant in Mice

• Published in: Blood 2023-11, Vol.142 (Supplement 1), p.683-683
• Main Authors: Schneider, Caitlin, Brake, Marisa A, Siebert-Mckenzie, Amy, Jurek, Adrianna, Cleuren, Audrey C, Hobbs, Linzi, Johnston, Alexander, Powers, Michael, Ahmed, Azaj, Jensen, Melissa, Menendez, Javier, Dayal, Sanjana, Washington, Anthony, Westrick, Randal Joseph
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2023-190196

Introduction: Venous thromboembolism (VTE) displays significant heritability, yet the genes explaining this heritability are not completely characterized. We previously identified that tissue factor pathway inhibitor heterozygosity ( Tfpi+/−) on the homozygous F5L background ( F5L/L) produces a lethal perinatal thrombotic phenotype. Using a sensitized ENU mutagenesis screen, we discovered an autosomal dominant missense mutation in the Actr2 gene (p.R258G, Actr2G) that suppresses thrombosis and restores survival to F5L/LTfpi+/− mice. Inheritance of the Actr2Gmutation is associated with nearly complete suppression of the lethal F5L/LTfpi+/- phenotype. Actr2 codes for the ARP2 protein, an essential component of the ARP2/3 complex, which mediates actin cytoskeletal rearrangements during platelet activation. We hypothesized that the Actr2G variant affects blood coagulation and platelet function to reduce thrombosis. Methods: To investigate potential effects of the Actr2G mutation on the coagulation cascade, prothrombin time (PT), activated partial thromboplastin time (aPTT), and plasma-dependent thrombin generation assays (TGA) were used to evaluate clot formation. A mouse tail clip assay was used to measure bleeding time and quantify blood loss. Finally, platelets were assessed for functional defects using platelet spreading and aggregometry assays. Results: Actr2 +/Gplasma had significantly prolonged PT and aPTT compared to wild type controls (N>17, p