PTPN22

PTPN22, located on chromosome 1, encodes protein tyrosine phosphatase non-receptor type 22, a phosphatase specific to lymphocytes. Linked to the molecular adapter protein CBL, PTPN22 may modulate CBL's role in T-cell receptor signaling. Its mutations are correlated with autoimmune diseases such as type 1 diabetes, rheumatoid arthritis, systemic lupus erythematosus, and Graves' disease. This phosphatase is pivotal in T cell signaling, dephosphorylating key kinases like Lck, ZAP70, Vav, and EB1 to curb TCR signaling. Furthermore, PTPN22 exerts a negative regulatory effect on platelet function and arterial thrombosis; its absence significantly reduces caudal bleeding time and speeds up arterial thrombosis, without impacting venous thrombosis or coagulation factors VIII and IX.