Casein kinase I isoforms contribute to platelet activation and thrombogenesis via RIPK3-MLKL signaling

Platelets are small, enucleate blood cells having life span of 10-12 days that play fundamental role in hemostasis and thrombosis. Casein Kinase 1 (CK1) is a serine/threonine-specific protein kinase that governs multiple cellular processes including circadian rhythm, morphogen signaling and apoptosis; however, its role in platelet biology and thrombogenesis remains unexplored. Employing a CK1-specific pharmacological inhibitors, we demonstrate here a pivotal role of CK1 in agonist-induced platelet activation. Inhibition of CK1 disrupts platelet functions that include aggregation, integrin activation, interaction with leukocytes, and thrombus formation under arterial shear ex vivo as well as in a murine model of thrombosis. CK1 maintains mitochondrial integrity by stabilizing inner mitochondrial membrane that propels energy metabolism in activated platelets. Notably, CK1 inhibition suppresses phosphorylation of receptor-interacting protein kinase 3 (RIPK3) and mixed lineage kinase domain-like protein (MLKL), key arbiters of platelet activation leading to necroptosis, thus mechanistically linking CK1 activity to platelet prothrombotic responses. Downregulation of CK1 did not affect primary hemostasis nor platelet viability while significantly deferring thrombus formation, which underscores its potential as a safe therapeutic option against thrombotic disorders. This study uncovers an emerging role of CK1 in unleashing of prothrombotic phenotype and positions CK1 as a potential target for antithrombotic measures.