Learn about Tofacitinib Citrate, an effective JAK inhibitor, and its role in disrupting the JAK-STAT pathway to inhibit gene transcription and cytokine production.
Tofacitinib Citrate is Used as a Janus Kinase (JAK) Inhibitor. Janus kinase (JAK) is a family of intracellular, non-receptor tyrosine kinases that transduce cytokine-mediated signals via the JAK-STAT pathway (Figure 2). The JAK family is comprised of several different subtypes, notably JAK1, JAK2, JAK3 and TYK2 in addition to a multitude of STAT proteins, STAT 1, STAT2, STAT3, STAT4, STAT5a, STAT5b and STAT6. The pathway is initiated by a ligand/cytokine acting as an extracellular signal and binding to a receptor on the cell membrane which in turn causes a structural or conformational change and thus consequent activation of the implicated JAK isoforms that are either homodimers or heterodimers.
Tofacitinib citrate inhibits the phosphorylation and activation of JAKs. JAKs cannot phosphorylate the cytokine receptors. Consequently, the receptors cannot contact with STATS. These latter are not phosphorylated and activated. Therefore, they cannot translocate to the nucleus. Gene transcription and cytokine production are inhibited.
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