Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway (JAK-STAT)

The Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway is a fundamental mechanism for translating extracellular signals from cytokines and growth factors into direct gene expression changes (Hu et al., 2021, Nature Reviews Rheumatology [1]). The pathway comprises four Janus kinases (JAK1, JAK2, JAK3, and TYK2) and seven STAT proteins (STAT1, STAT2, STAT3, STAT4, STAT5A, STAT5B, and STAT6) that operate downstream of type I and II cytokine receptors (Villarino et al., 2017, Journal of Immunology [2]). Upon ligand binding, JAKs are activated and phosphorylate the receptor cytoplasmic tails, creating docking sites for STATs, which are then phosphorylated, dimerize, and translocate to the nucleus (Banerjee et al., 2017, Drugs [3]). This pathway is essential for hematopoiesis, immune system homeostasis, and inflammatory responses (O'Shea et al., 2015, NEJM [4]). Dysregulation, such as gain-of-function mutations in JAK2, is a hallmark of myeloproliferative neoplasms, while overactivation contributes to autoimmune diseases like rheumatoid arthritis and inflammatory bowel disease (Vainchenker & Constantinescu, 2013, Blood [5]). Therapeutic targeting of this pathway primarily involves small-molecule JAK inhibitors, which compete with ATP in the kinase domain to block signal transduction (Schwartz et al., 2017, Nature Reviews Drug Discovery [6]).

Other names

JAK-STAT signaling cascadeJAK-STAT pathwayJanus kinase-STAT pathway

Inhibition of Janus kinase (JAK) enzymatic activity, which prevents the phosphorylation and activation of Signal Transducer and Activator of Transcription (STAT) proteins, thereby blocking their translocation to the nucleus and subsequent regulation of gene expression.