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Janus kinase 2 (commonly called JAK2) is a non-receptor tyrosine kinase.It is a member of the Janus kinase family and has been implicated in signaling by members of the type II cytokine receptor family (e.g. interferon receptors), the GM-CSF receptor family (IL-3R, IL-5R and GM-CSF-R), the gp130 receptor family (e.g., IL-6R), and the single chain receptors (e.g. Epo-R, Tpo-R, GH-R, PRL-R).
[9] [10] There are three known genetic mutations that cause ET. The most common genetic mutation is a JAK2 mutation. Roughly 50% of the population of ET patients have this mutation. The JAK 2 gene signals a protein that promotes the growth of cells. The protein is part of a signaling pathway called the JAK/STAT pathway.
A mutation in the JAK2 kinase (V617F) is strongly associated with polycythemia vera. [18] [19] While it is a JAK2 V617F mutation in 95% of patients, JAK2 exon 12 mutations have also been observed. [20] The V617F mutation is not inherited, but develops as a somatic mutation in the erythroid progenitor cells. [21]
Polycythemia vera (PV) is associated most often with the JAK2 V617F mutation greater than 95% of cases, whereas the remainder has a JAK2 exon 12 mutations. High hemoglobin or hematocrit counts are required, as is a bone marrow examination showing "prominent erythroid , granulocytic and megakaryocytic proliferation with pleomorphic, mature ...
Janus kinase (JAK) is a family of intracellular, non-receptor tyrosine kinases that transduce cytokine-mediated signals via the JAK-STAT pathway.They were initially named "just another kinase" 1 and 2 (since they were just two of many discoveries in a PCR-based screen of kinases), [1] but were ultimately published as "Janus kinase".
The underlying cause of PMF is almost always related to an acquired mutation in JAK2, CALR or MPL in a hematopoietic stem/progenitor cell in the bone marrow. [5] There is an association between mutations to the JAK2, CALR, or MPL genes and myelofibrosis. [6]
JAK2 phosphorylates the BCR-ABL fusion protein at Y177 and stabilizes the fusion protein, strengthening tumorigenic cell signaling. JAK2 mutations have been shown to be central to myeloproliferative neoplasms and JAK kinases play a central role in driving hematologic malignancies (JAK blood journal).
Also, other studies propose that SHP-2 may increase JAK2 activity, and promote JAK2/STAT5 signalling. [50] It is still unknown how SHP2 can both inhibit and promote JAK-STAT signalling in the JAK2/STAT5 pathway; one theory is that SHP-2 may promote activation of JAK2, but inhibit STAT5 by removing phosphate groups from it. [38] CD45.