RE: Tyk 2 SDC1801 Tyk2 Jak117 Jun 2021 23:33
This gene encodes a member of the tyrosine kinase and, to be more specific, the Janus kinases (JAKs) protein families. This protein associates with the cytoplasmic domain of type I and type II cytokine receptors and promulgate cytokine signals by phosphorylating receptor subunits. It is also component of both the type I and type III interferon signaling pathways. As such, it may play a role in anti-viral immunity.[6]
Cytokines play pivotal roles in immunity and inflammation by regulating the survival, proliferation, differentiation, and function of immune cells, as well as cells from other organ systems.[8] Hence, targeting cytokines and their receptors is an effective means of treating such disorders. Type I and II cytokine receptors associate with Janus family kinases (JAKs) to affect intracellular signaling. Cytokines including interleukins, interferons and hemopoietins activate the Janus kinases, which associate with their cognate receptors.[9]
The mammalian JAK family has four members: JAK1, JAK2, JAK3 and tyrosine kinase 2 (TYK2).[7] The connection between Jaks and cytokine signaling was first revealed when a screen for genes involved in interferon type I (IFN-1) signaling identified Tyk2 as an essential element, which is activated by an array of cytokine receptors.[10] Tyk2 has broader and profound functions in humans than previously appreciated on the basis of analysis of murine models, which indicate that Tyk2 functions primarily in IL-12 and type I-IFN signaling. Tyk2 deficiency has more dramatic effects in human cells than in mouse cells. However, in addition to IFN-a and -ß and IL-12 signaling, Tyk2 has major effects on the transduction of IL-23, IL-10, and IL-6 signals. Since, IL-6 signals through the gp-130 receptor-chain that is common to a large family of cytokines, including IL-6, IL-11, IL-27, IL-31, oncostatin M (OSM), ciliary neurotrophic factor, cardiotrophin 1, cardiotrophin-like cytokine, and LIF, Tyk2 might also affect signaling through these cytokines. Recently, it has been recognized that IL-12 and IL-23 share ligand and receptor subunits that activate Tyk2. IL-10 is a critical anti-inflammatory cytokine, and IL-10-/- mice suffer from fatal, systemic autoimmune disease.
Tyk2 is activated by IL-10, and its deficiency affects the ability to generate and respond to IL-10.[11] Under physiological conditions, immune cells are, in general, regulated by the action of many cytokines and it has become clear that cross-talk between different cytokine-signalling pathways is involved in the regulation of the JAK–STAT pathway.[12]