Signal transducer and activator of transcription signaling pathway downstream of Thrombopoietin receptor (STAT signaling (TPO-R))

The STAT signaling pathway downstream of the Thrombopoietin receptor (TPO-R), also known as MPL, is a fundamental regulatory cascade for hematopoiesis, specifically governing the production of platelets (megakaryocytopoiesis) (UniProt P40238). Activation begins when the hormone thrombopoietin (TPO) binds to the extracellular domain of MPL, inducing a conformational change that activates associated Janus kinase 2 (JAK2) molecules (PubMed 24014238). These kinases phosphorylate specific tyrosine residues on the receptor, creating docking sites for Signal Transducer and Activator of Transcription (STAT) proteins, primarily STAT3, STAT5A, and STAT5B (PubMed 10713348). Once recruited, STATs are phosphorylated by JAK2, allowing them to dimerize and translocate into the nucleus to initiate the transcription of genes essential for the survival and maturation of megakaryocyte progenitors. Pathological overactivation of this pathway, frequently caused by the JAK2 V617F mutation or MPL gain-of-function mutations, leads to myeloproliferative neoplasms such as essential thrombocythemia and polycythemia vera (StatPearls: Myeloproliferative Neoplasms). Conversely, therapeutic targeting of this pathway involves TPO-R agonists like eltrombopag and romiplostim to treat thrombocytopenia, or JAK inhibitors like ruxolitinib to manage myeloproliferative diseases (FDA: Promacta, Jakafi).

Other names

JAK-STAT signaling pathway (MPL)TPO-induced STAT activationMPL-STAT pathwayThrombopoietin receptor signaling cascade

Thrombopoietin receptor agonism and Janus kinase inhibition