Janus kinase 2 (JAK2) (JAK2)

Janus kinase 2 (JAK2) is a non-receptor tyrosine kinase that plays a pivotal role in the signaling pathways of various cytokines and growth factors, particularly those essential for hematopoiesis and immune response (UniProt P29966). It belongs to the Janus kinase family and functions by phosphorylating Signal Transducers and Activators of Transcription (STAT) proteins upon receptor activation, which then regulate gene expression related to cell proliferation and survival (NIH, 2023). Mutations in the JAK2 gene, such as the common V617F substitution, lead to constitutive activation of the JAK-STAT pathway and are strongly associated with myeloproliferative neoplasms (MPNs) like myelofibrosis and polycythemia vera (PubMed, PMID: 15752413). As a therapeutic target, JAK2 is inhibited by small-molecule drugs like fedratinib, which competitively bind to the ATP-binding site of the kinase domain to suppress overactive signaling (FDA, 2019). These inhibitors are primarily used to manage symptoms and reduce splenomegaly in patients with intermediate or high-risk myelofibrosis. However, targeting JAK2 can lead to adverse effects such as cytopenias and, in the specific case of fedratinib, potential neurological issues like Wernicke's encephalopathy due to thiamine interference (StatPearls, 2023).

Other names

JAK-2Tyrosine-protein kinase JAK2JAK2_HUMANJanus kinase 2

Selective inhibition of the Janus kinase 2 (JAK2) enzyme by competing for the ATP-binding site, thereby preventing the phosphorylation of STAT proteins and interrupting the JAK-STAT signaling pathway involved in cell proliferation and hematopoiesis (FDA, 2019; PubChem).