Protein tyrosine phosphatase non-receptor type 22 (PTPN22)

Protein tyrosine phosphatase non-receptor type 22 (PTPN22) is a cytoplasmic enzyme encoded by the PTPN22 gene and a member of the PEST family of protein tyrosine phosphatases. It is a pivotal negative regulator of T cell receptor and B cell receptor signaling, modulating immune activation, tolerance, and homeostasis in lymphocytes. PTPN22 interacts with signaling molecules such as LCK, ZAP70, CSK, and TRAF3, and its activities influence cell adhesion/motility, regulatory T cell survival, and cytokine responses. Genetic variants, particularly the R620W polymorphism, are strongly linked to increased risk for multiple autoimmune diseases and influence patient outcomes in conditions such as cancer, where immune checkpoint therapies are used. As such, PTPN22 is a promising therapeutic target, but clinical interventions must balance enhanced immune activation against the potential for autoimmunity. No approved drugs specifically inhibit PTPN22, but it remains a subject of active therapeutic research.

Other names

PEST-domain Enriched Phosphatase (PEP)Lymphoid phosphatase (LYP)PTPN22

Inhibition of PTPN22 phosphatase activity: enhances T cell activation and antitumor immunity, potentially effective in cancer immunotherapy. Modulation of immune tolerance: altering PTPN22 function can shift immune thresholds, relevant for both autoimmunity and cancer. Dephosphorylation of immune signaling intermediates: reduces TCR and BCR signaling intensity.