This Key Event Relationship is licensed under the Creative Commons BY-SA license. This license allows reusers to distribute, remix, adapt, and build upon the material in any medium or format, so long as attribution is given to the creator. The license allows for commercial use. If you remix, adapt, or build upon the material, you must license the modified material under identical terms.
Inhibition of JAK3 leads to STAT5 inhibition
Key Event Relationship Overview
AOPs Referencing Relationship
|AOP Name||Adjacency||Weight of Evidence||Quantitative Understanding||Point of Contact||Author Status||OECD Status|
|Inhibition of JAK3 leading to impairment of T-Cell Dependent Antibody Response||adjacent||High||High||Yasuhiro Yoshida (send email)||Under development: Not open for comment. Do not cite||Under Development|
Life Stage Applicability
|All life stages||High|
Key Event Relationship Description
Nelson et al. reported that a membrane proximal region of the interleukin-2 receptor gamma c chain sufficient for Jak kinase activation and induction of proliferation in T cells (Nelson, et al. 1996). Furthermore, Kirken RA et al. demonstrated that activation of JAK3, but not JAK1, is critical for IL-2-induced proliferation and STAT5 recruitment by a COOH-terminal region of the IL-2 receptor beta-chain (Kirken, et al. 1995). Therefore, STAT activation is regulated by JAK via phosphorylation. Thus, JAK inhibitors commonly interfere with STAT activation.
Evidence Collection Strategy
Evidence Supporting this KER
STAT5 refer to two proteins that share 94% structural homology and are transcribed from separate genes, STAT5A and STAT5B. Binding of these extracellular ligands to their target receptors induces the activation of receptor-associated JAK kinases that phosphorylate key tyrosine residues within the receptor, providing docking sites for the SRC homology 2 (SH2) domains of the inactive cytoplasmic STAT5 monomers. STAT5 is then phosphorylated at specific tyrosine residues, either Y694 (STAT5A) or Y699 (STAT5B) of the C-terminus. Subsequently, STAT5 undergoes a conformational change and phosphorylated STAT5 monomers form either homo- or hetero- STAT5X-STATX dimers through reciprocal phosphotyrosine–SH2 interactions (Cumaraswamy, et al. 2014, Tothova, et al. 2021). This means that STAT5 will never be activated without this phosphorylation step by JAK3.
STAT5 plays a major role in regulating vital cellular functions, such as proliferation, differentiation, and apoptosis, of hematopoietic and immune cells (Wakao, et al. 1992). STAT5 is activated by JAK3 phosphorylation of a single tyrosine residue (Y694).
Uncertainties and Inconsistencies
Known modulating factors
Dose-response analysis of the effects of RB1 on JAK3 kinase activity showed that RB1 inhibits JAK3 kinase activity in a dose-dependent manner with an IC50 value of 40 nM, without inhibiting JAK1, JAK2, or TYK2 (Pei, et al. 2018).
Normal rats were administered peficitinib at 10 and 20 mg/kg. Thirteen hours later, the animals were bled and STAT5 phosphorylation was assessed. IL-2-induced STAT5 phosphorylation of CD3-positive lymphocytes in peripheral blood from the peficitinib-treated rats was suppressed by 37% at a dose of 10 mg/kg and 78% at 20 mg/kg (Gianti and Zauhar 2015).
The enzymatic activities against JAK1, JAK2, JAK3, and TYK2 were immediately tested in CTLL-2 cells using a Caliper Mobility Shift Assay with an ATP concentration at Km (Pei, et al. 2018). CTLL-2 cells were treated with 10 µM adenosine (plus coformycin) for 15 min at 37°C and then stimulated with IL-2 (10 U/mL) for different lengths of time (5 min-12 h). Adenosine dramatically decreased dose-dependent STAT5A/B tyrosine phosphorylation in response to IL-2 over the entire 12 h time course (Zhang, et al. 2004).
Known Feedforward/Feedback loops influencing this KER
Domain of Applicability
Al-Shami A, Mahanna W, Naccache PH. 1998. Granulocyte-macrophage colony-stimulating factor-activated signaling pathways in human neutrophils. Selective activation of Jak2, Stat3, and Stat5b. J Biol Chem 273:1058-1063. DOI: 10.1074/jbc.273.2.1058.
Cumaraswamy AA, Lewis AM, Geletu M, Todic A, Diaz DB, Cheng XR, Brown CE, Laister RC, Muench D, Kerman K, Grimes HL, Minden MD, Gunning PT. 2014. Nanomolar-Potency Small Molecule Inhibitor of STAT5 Protein. ACS Med Chem Lett 5:1202-1206. DOI: 10.1021/ml500165r.
Gianti E, Zauhar RJ. 2015. An SH2 domain model of STAT5 in complex with phospho-peptides define "STAT5 Binding Signatures". J Comput Aided Mol Des 29:451-470. DOI: 10.1007/s10822-015-9835-6.
Kirken RA, Rui H, Malabarba MG, Howard OM, Kawamura M, O'Shea JJ, Farrar WL. 1995. Activation of JAK3, but not JAK1, is critical for IL-2-induced proliferation and STAT5 recruitment by a COOH-terminal region of the IL-2 receptor beta-chain. Cytokine 7:689-700. DOI: S1043466685700816 [pii]
Nelson BH, Lord JD, Greenberg PD. 1996. A membrane-proximal region of the interleukin-2 receptor gamma c chain sufficient for Jak kinase activation and induction of proliferation in T cells. Mol Cell Biol 16:309-317. DOI: 10.1128/MCB.16.1.309.
Pei H, He L, Shao M, Yang Z, Ran Y, Li D, Zhou Y, Tang M, Wang T, Gong Y, Chen X, Yang S, Xiang M, Chen L. 2018. Discovery of a highly selective JAK3 inhibitor for the treatment of rheumatoid arthritis. Sci Rep 8:5273. DOI: 10.1038/s41598-018-23569-y.
Tothova Z, Tomc J, Debeljak N, Solar P. 2021. STAT5 as a Key Protein of Erythropoietin Signalization. Int J Mol Sci 22. DOI: 7109 [pii]10.3390/ijms22137109ijms22137109 [pii].
Wakao H, Schmitt-Ney M, Groner B. 1992. Mammary gland-specific nuclear factor is present in lactating rodent and bovine mammary tissue and composed of a single polypeptide of 89 kDa. J Biol Chem 267:16365-16370.
Zhang H, Conrad DM, Butler JJ, Zhao C, Blay J, Hoskin DW. 2004. Adenosine acts through A2 receptors to inhibit IL-2-induced tyrosine phosphorylation of STAT5 in T lymphocytes: role of cyclic adenosine 3',5'-monophosphate and phosphatases. J Immunol 173:932-944. DOI: 10.4049/jimmunol.173.2.932.