Janus kinase-Signal Transducer and Activator of Transcription signaling pathway (JAK-STAT signaling pathway)

The Janus kinase-Signal Transducer and Activator of Transcription (JAK-STAT) signaling pathway is a vital transmembrane mechanism that conveys chemical signals from outside the cell directly to the nucleus to regulate gene expression (Hu et al., 2021, PubMed). The pathway is initiated when ligands, such as cytokines or growth factors, bind to their specific cell-surface receptors, causing the recruitment and activation of Janus kinase family members (JAK1, JAK2, JAK3, and TYK2). These kinases then phosphorylate the receptor, creating docking sites for STAT proteins, which are themselves phosphorylated, undergo dimerization, and translocate into the nucleus to act as transcription factors (NIH, 2022; StatPearls, 2023). This pathway is essential for fundamental biological processes including the regulation of the immune system, hematopoiesis, and cell growth control (Wikipedia, 2023). Dysregulation or mutations within this axis are strongly linked to various pathologies, particularly autoimmune disorders like rheumatoid arthritis and hematologic malignancies such as myelofibrosis. Consequently, this pathway has become a major therapeutic focus, with numerous small-molecule JAK inhibitors (JAKinibs) approved to treat inflammatory diseases and cancers by selectively blocking kinase activity (Banerjee et al., 2017, PubMed; FDA, 2023).

Other names

JAK-STAT pathwayJAK/STAT signaling cascadeJanus kinase-STAT signalingJanus kinase/signal transducers and activators of transcription pathway

Small-molecule inhibitors (JAKinibs) primarily bind to the ATP-binding site of the Janus kinase (JAK) catalytic domain, which prevents the kinase from phosphorylating itself, the associated cytokine receptor, and the downstream STAT proteins, thereby blocking the translocation of STAT dimers to the nucleus and subsequent gene transcription (StatPearls, 2023; NIH, 2022).