| Structural highlights
Function
JAK2_MOUSE Non-receptor tyrosine kinase involved in various processes such as cell growth, development, differentiation or histone modifications. Mediates essential signaling events in both innate and adaptive immunity. In the cytoplasm, plays a pivotal role in signal transduction via its association with type I receptors such as growth hormone (GHR), prolactin (PRLR), leptin (LEPR), erythropoietin (EPOR), thrombopoietin (THPO); or type II receptors including IFN-alpha, IFN-beta, IFN-gamma and multiple interleukins. Following ligand-binding to cell surface receptors, phosphorylates specific tyrosine residues on the cytoplasmic tails of the receptor, creating docking sites for STATs proteins. Subsequently, phosphorylates the STATs proteins once they are recruited to the receptor. Phosphorylated STATs then form homodimer or heterodimers and translocate to the nucleus to activate gene transcription. For example, cell stimulation with erythropoietin (EPO) during erythropoiesis leads to JAK2 autophosphorylation, activation, and its association with erythropoietin receptor (EPOR) that becomes phosphorylated in its cytoplasmic domain. Then, STAT5 (STAT5A or STAT5B) is recruited, phosphorylated and activated by JAK2. Once activated, dimerized STAT5 translocates into the nucleus and promotes the transcription of several essential genes involved in the modulation of erythropoiesis. In addition, JAK2 mediates angiotensin-2-induced ARHGEF1 phosphorylation. Plays a role in cell cycle by phosphorylating CDKN1B. Cooperates with TEC through reciprocal phosphorylation to mediate cytokine-driven activation of FOS transcription. In the nucleus, plays a key role in chromatin by specifically mediating phosphorylation of 'Tyr-41' of histone H3 (H3Y41ph), a specific tag that promotes exclusion of CBX5 (HP1 alpha) from chromatin.[1] [2] [3] [4] [5] [6] [7] [8]
Publication Abstract from PubMed
The inhibitory protein SOCS3 plays a key part in the immune and hematopoietic systems by regulating signaling induced by specific cytokines. SOCS3 functions by inhibiting the catalytic activity of Janus kinases (JAKs) that initiate signaling within the cell. We determined the crystal structure of a ternary complex between mouse SOCS3, JAK2 (kinase domain) and a fragment of the interleukin-6 receptor beta-chain. The structure shows that SOCS3 binds JAK2 and receptor simultaneously, using two opposing surfaces. While the phosphotyrosine-binding groove on the SOCS3 SH2 domain is occupied by receptor, JAK2 binds in a phosphoindependent manner to a noncanonical surface. The kinase-inhibitory region of SOCS3 occludes the substrate-binding groove on JAK2, and biochemical studies show that it blocks substrate association. These studies reveal that SOCS3 targets specific JAK-cytokine receptor pairs and explains the mechanism and specificity of SOCS action.
SOCS3 binds specific receptor-JAK complexes to control cytokine signaling by direct kinase inhibition.,Kershaw NJ, Murphy JM, Liau NP, Varghese LN, Laktyushin A, Whitlock EL, Lucet IS, Nicola NA, Babon JJ Nat Struct Mol Biol. 2013 Apr;20(4):469-76. doi: 10.1038/nsmb.2519. Epub 2013 Mar, 3. PMID:23454976[9]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Huang LJ, Constantinescu SN, Lodish HF. The N-terminal domain of Janus kinase 2 is required for Golgi processing and cell surface expression of erythropoietin receptor. Mol Cell. 2001 Dec;8(6):1327-38. PMID:11779507
- ↑ Guilluy C, Bregeon J, Toumaniantz G, Rolli-Derkinderen M, Retailleau K, Loufrani L, Henrion D, Scalbert E, Bril A, Torres RM, Offermanns S, Pacaud P, Loirand G. The Rho exchange factor Arhgef1 mediates the effects of angiotensin II on vascular tone and blood pressure. Nat Med. 2010 Feb;16(2):183-90. doi: 10.1038/nm.2079. Epub 2010 Jan 24. PMID:20098430 doi:10.1038/nm.2079
- ↑ Jakel H, Weinl C, Hengst L. Phosphorylation of p27Kip1 by JAK2 directly links cytokine receptor signaling to cell cycle control. Oncogene. 2011 Aug 11;30(32):3502-12. doi: 10.1038/onc.2011.68. Epub 2011 Mar 21. PMID:21423214 doi:10.1038/onc.2011.68
- ↑ Witthuhn BA, Quelle FW, Silvennoinen O, Yi T, Tang B, Miura O, Ihle JN. JAK2 associates with the erythropoietin receptor and is tyrosine phosphorylated and activated following stimulation with erythropoietin. Cell. 1993 Jul 30;74(2):227-36. PMID:8343951
- ↑ Nakamura N, Chin H, Miyasaka N, Miura O. An epidermal growth factor receptor/Jak2 tyrosine kinase domain chimera induces tyrosine phosphorylation of Stat5 and transduces a growth signal in hematopoietic cells. J Biol Chem. 1996 Aug 9;271(32):19483-8. PMID:8702638
- ↑ Yamashita Y, Watanabe S, Miyazato A, Ohya Ki, Ikeda U, Shimada K, Komatsu N, Hatake K, Miura Y, Ozawa K, Mano H. Tec and Jak2 kinases cooperate to mediate cytokine-driven activation of c-fos transcription. Blood. 1998 Mar 1;91(5):1496-507. PMID:9473212
- ↑ Parganas E, Wang D, Stravopodis D, Topham DJ, Marine JC, Teglund S, Vanin EF, Bodner S, Colamonici OR, van Deursen JM, Grosveld G, Ihle JN. Jak2 is essential for signaling through a variety of cytokine receptors. Cell. 1998 May 1;93(3):385-95. PMID:9590173
- ↑ Neubauer H, Cumano A, Muller M, Wu H, Huffstadt U, Pfeffer K. Jak2 deficiency defines an essential developmental checkpoint in definitive hematopoiesis. Cell. 1998 May 1;93(3):397-409. PMID:9590174
- ↑ Kershaw NJ, Murphy JM, Liau NP, Varghese LN, Laktyushin A, Whitlock EL, Lucet IS, Nicola NA, Babon JJ. SOCS3 binds specific receptor-JAK complexes to control cytokine signaling by direct kinase inhibition. Nat Struct Mol Biol. 2013 Apr;20(4):469-76. doi: 10.1038/nsmb.2519. Epub 2013 Mar, 3. PMID:23454976 doi:http://dx.doi.org/10.1038/nsmb.2519
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