The KXD1-TSPAN14 axis controls megakaryopoiesis and platelet production via Notch signaling.

Platelets, derived from megakaryocytes (MKs), are crucial for blood clotting. Identifying genes that regulate MK development and platelet production could advance treatments for blood disorders. We found that KxDL motif-containing 1 (Kxd1) knockout (KO) mice exhibited doubled platelet counts without impairment of individual platelet function. Kxd1-KO mice showed enhanced MK progenitor differentiation and rapid polyploid MK formation in vivo and in vitro. Mechanistically, KXD1 deficiency increased TSPAN14 levels by disrupting its endolysosomal trafficking, thus activating the ADAM10-Notch axis to drive MK polyploidization. In platelet/MK-specific Tspan14-KO mice, TSPAN14 deficiency impaired MK polyploidization and maturation. Our findings reveal that KXD1 is a key negative regulator of Notch signaling, controlling megakaryopoiesis mediated by TSPAN14. The KXD1-TSPAN14 axis is a promising therapeutic target for platelet disorders, including thrombocytopenia and myeloproliferative neoplasms, and as an interventional pathway for platelet production in transfusion medicine.