scholarly journals Characterization of JAK1 Pseudokinase Domain in Cytokine Signaling

Cancers ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 78 ◽  
Author(s):  
Juuli Raivola ◽  
Teemu Haikarainen ◽  
Olli Silvennoinen
Keyword(s):  
Biochemical Characterization ◽  
Myeloproliferative Neoplasms ◽  
Interleukin 2 ◽  
Binding Pocket ◽  
Janus Kinase ◽  
Regulatory Function ◽  
Cytokine Signaling ◽  
Interferon Α ◽  
Atp Binding ◽  
Receptor Complexes

The Janus kinase-signal transducer and activator of transcription protein (JAK-STAT) pathway mediates essential biological functions from immune responses to haematopoiesis. Deregulated JAK-STAT signaling causes myeloproliferative neoplasms, leukaemia, and lymphomas, as well as autoimmune diseases. Thereby JAKs have gained significant relevance as therapeutic targets. However, there is still a clinical need for better JAK inhibitors and novel strategies targeting regions outside the conserved kinase domain have gained interest. In-depth knowledge about the molecular details of JAK activation is required. For example, whether the function and regulation between receptors is conserved remains an open question. We used JAK-deficient cell-lines and structure-based mutagenesis to study the function of JAK1 and its pseudokinase domain (JH2) in cytokine signaling pathways that employ JAK1 with different JAK heterodimerization partner. In interleukin-2 (IL-2)-induced STAT5 activation JAK1 was dominant over JAK3 but in interferon-γ (IFNγ) and interferon-α (IFNα) signaling both JAK1 and heteromeric partner JAK2 or TYK2 were both indispensable for STAT1 activation. Moreover, IL-2 signaling was strictly dependent on both JAK1 JH1 and JH2 but in IFNγ signaling JAK1 JH2 rather than kinase activity was required for STAT1 activation. To investigate the regulatory function, we focused on two allosteric regions in JAK1 JH2, the ATP-binding pocket and the αC-helix. Mutating L633 at the αC reduced basal and cytokine induced activation of STAT in both JAK1 wild-type (WT) and constitutively activated mutant backgrounds. Moreover, biochemical characterization and comparison of JH2s let us depict differences in the JH2 ATP-binding and strengthen the hypothesis that de-stabilization of the domain disturbs the regulatory JH1-JH2 interaction. Collectively, our results bring mechanistic understanding about the function of JAK1 in different receptor complexes that likely have relevance for the design of specific JAK modulators.

scholarly journals A Role of Suppressor of Cytokine Signaling 3 (SOCS3/CIS3/SSI3) in CD28-mediated Interleukin 2 Production

2003 ◽  
Vol 197 (4) ◽  
pp. 425-436 ◽  
Author(s):  
Akira Matsumoto ◽  
Yoh-ichi Seki ◽  
Ryosuke Watanabe ◽  
Katsuhiko Hayashi ◽  
James A. Johnston ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Interleukin 2 ◽  
Sh2 Domain ◽  
Janus Kinase ◽  
Expression Level ◽  
Cytokine Signaling ◽  
Suppressor Of Cytokine Signaling ◽  
Cd28 Costimulation

Suppressor of cytokine signaling (SOCS)3 has been characterized as a negative feedback regulator in cytokine-mediated Janus kinase signal transducer and activator of transcription signaling. However, this study shows that T cells from transgenic mice expressing SOCS3 exhibit a significant reduction in interleukin (IL)-2 production induced by T cell receptor cross-linking when T cells are costimulated with CD28. Decreased protein expression in SOCS3+/− mice enhanced CD28-mediated IL-2 production, clearly indicating the correlation between expression level of SOCS3 and IL-2 production ability. The SOCS3 protein interacted with phosphorylated CD28 through its SH2 domain but not the kinase inhibitory region. In addition, a point mutation in the SOCS3 SH2 domain attenuated the inhibition of CD28 function in IL-2 promoter activation. Committed T helper (Th)2 cells exclusively expressed SOCS3 and production of Th2 cytokines, such as IL-4 and IL-5, was much less dependent on CD28 costimulation compared with interferon γ and IL-2 production in Th1 cells. Consistent with this notion, the expression level of SOCS3 in early T cell activation influenced the ability of IL-2 production induced by CD28 costimulation. Therefore, the SOCS3 may play an alternative role in prohibiting excessive progression of CD28-mediated IL-2 production.

scholarly journals Down-modulation of Type 1 Interferon Responses by Receptor Cross-competition for a Shared Jak Kinase

2001 ◽  
Vol 276 (50) ◽  
pp. 47004-47012 ◽  
Author(s):  
Elisabetta Dondi ◽  
Els Pattyn ◽  
Georges Lutfalla ◽  
Xaveer Van Ostade ◽  
Gilles Uzé ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Transcriptional Response ◽  
Erythropoietin Receptor ◽  
Cellular Systems ◽  
Janus Kinase ◽  
Model Systems ◽  
Interleukin 12 ◽  
Interferon Α ◽  
Receptor Complexes

In contrast to the large number of class I and II cytokine receptors, only four Janus kinase (Jak) proteins are expressed in mammalian cells, implying the shared use of these kinases by many different receptor complexes. Consequently, if receptor numbers exceed the amount of available Jak, cross-interference patterns can be expected. We have engineered two model cellular systems expressing two different exogenous Tyk2-interacting receptors. A receptor chimera was generated wherein the extracellular part of the interferon type 1 receptor (Ifnar1) component of the interferon-α/β receptor is replaced by the equivalent domain of the erythropoietin receptor. Despite Tyk2 activation, erythropoietin treatment of cells expressing this erythropoietin receptor/Ifnar1 chimera did not evoke any detectable IFN-type response. However, a dose-dependent interference with signal transduction via the endogenous Ifnar complex was found for STAT1, STAT2, STAT3, Tyk2, and Jak1 activation, for gene induction, and for antiviral activity. In a similar approach, cells expressing the β1 chain of the interleukin-12 receptor showed a reduced transcriptional response to IFN-α as well as reduced STAT and kinase activation. In both model systems, titration of the Tyk2 kinase away from the Ifnar1 receptor chain accounts for the observed cross-interference.

Targeting the Genetic Resistance of JAK2 and BCR/ABL by TG101348

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3765-3765
Author(s):  
Meenu Kesarwani ◽  
Mohammad Azam
Keyword(s):  
Active Site ◽  
Myeloproliferative Neoplasms ◽  
Substrate Binding ◽  
Genetic Resistance ◽  
Structural Modeling ◽  
Binding Pocket ◽  
Janus Kinase ◽  
Substrate Binding Pocket ◽  
Modeling Studies

Abstract Abstract 3765 The inherent preponderance of genetic resistance against tyrosine kinase inhibitor (TKI) therapy poses significant challenge for effective treatments. Recent approval of Janus kinase 2 (JAK2) inhibitor INCB018424 (Jakafi, ruxolitinib) for the treatment of myeloproliferative neoplasms (MPNs) prompted us to identify resistant mutations that may pose clinical challenge. In vitro drug selection screening against two leading JAK2 inhibitors (INCB018424 and TG101348) were performed. Here we show that like other kinase inhibitors, INCB018424 is prone to genetic resistance while TG101348 is recalcitrant to develop in vitro resistance. Sequencing of INCB018424 resistant clones identified 211 amino acid substitutions spanning across FERM, SH2, JH2 and the kinase domain. Biochemical and structural modeling studies of these mutants demonstrate that mutations within the active site confer resistance either by direct steric hindrance or destabilizing the architecture of the active site. And mutations from the allosteric sites destabilize the intermediary state of the active and inactive conformations of JAK2 to which INCB018424 preferentially binds. Furthermore, these resistant variants are cross resistant to other JAK2 inhbitors (Lestaurtinib, CYT-387 and AZD1480). In contrast, these resistant variants are fully sensitive to TG101348 supporting the lack of resistance against this compound as observed during in vitro screening. Structural modeling studies revealed that TG101348 stabilizes the active conformation of the kinase and binds to the substrate-binding pocket. Mutations affecting the substrate-binding pocket may either alter substrate binding/phosphorylation or encode an incompetent kinase that blocks the emergence of resistance. Because JAK2 and BCR/ABL share a common substrate, STAT5, they might have similar architecture of the substrate-binding pocket, which may allow the inhibition of BCR/ABL by TG101348. Indeed, TG101348 can inhibit both native and gatekeeper variants of BCR/ABL and in vitro drug resistant screening failed to develop emergence of resistant clones. These studies provide evidence that the patients developing resistant variants of JAK2 and BCR/ABL can be treated with TG101348 and support for future drug design geared towards targeting the substrate binding sites in other oncogenic kinases for better and sustained therapeutic response. Disclosures: No relevant conflicts of interest to declare.

The JAK2-Selective Inhibitor NS-018 Preferentially Suppresses CFU-GM Colony Formation By Bone-Marrow Cells From High-Risk Myelodysplastic Syndrome Patients

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1286-1286
Author(s):  
Ayumi Kodama ◽  
Haruna Naito ◽  
Yohei Nakaya ◽  
Ayako Tamura ◽  
Yoshiaki Chinen ◽  
...  
Keyword(s):  
Bone Marrow ◽  
High Risk ◽  
Colony Formation ◽  
Myeloproliferative Neoplasms ◽  
Selective Inhibitor ◽  
Janus Kinase ◽  
Refractory Anemia ◽  
Cytokine Signaling ◽  
Dependent Manner ◽  
Normal Cells

Abstract Background Cell signaling mediated by the JAK2-STAT (Janus kinase 2-signal transducer and activator of transcription) pathway plays a critical role in hematopoiesis, and its aberrant activation is associated with the progression of hematological malignancies. For instance, somatic mutations in the JAK2 gene that lead to constitutive activation of STATs are involved in the pathogenesis of myeloproliferative neoplasms (MPN) and refractory anemia with ringed sideroblasts with thrombocytosis, one of the myelodysplastic/myeloproliferative neoplasms, unclassifiable (MDS/MPN, U). In addition, insufficient inactivation of the JAK-STAT pathway due to repression of SOCS-1 (suppressor of cytokine signaling 1) through hypermethylation of the SOCS-1 gene is involved in the disease progression of high-risk myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) (Brakensiek et al.; Br. J. Haematol. 2005;130:209). These observations prompted us to investigate the effect of the JAK2-selective inhibitor NS-018, which is in an early-phase clinical trial for MPN, on the colony formation by bone marrow hematopoietic progenitor cells from high-risk de novo MDS patients and the phosphorylation status of STAT3 in these cells. Methods Bone marrow mononuclear cells (BMMNCs) from six MDS patients and three healthy volunteers were collected with informed consent in accordance with the Declaration of Helsinki and with the approval of the Institutional Review Board. The MDS subtypes of the six patients included two RCMD, three RAEB-1 and one RAEB-2 according to the WHO classification. All MDS patients had complex cytogenetic abnormalities and their prognostic risks were defined to be high (N=1) or very high (N=5) in the IPSS-R. Commercially available normal human CD34+ BM cells were also examined for comparison. Cells were incubated in methylcellulose medium containing cytokines with or without NS-018. Burst forming unit-erythroid (BFU-E) and colony forming unit-granulocyte/macrophage (CFU-GM) were scored on day 14 of culture. Colony-forming cells were then collected and subjected to western blotting analysis. Results We first examined the colony-formation capacity of MDS-derived BMMNCs. CFU-GM colony formation was observed in four of six MDS samples, although the absolute CFU-GM numbers from MDS BMMNCs were less than those from normal BMMNCs and normal CD34+BM cells. MDS-derived BMMNCs produced larger numbers of CFU-GM colonies (78–99% of total colonies) than BFU-E, similar to the findings usually observed in AML, whereas normal BMMNCs and normal CD34+BM cells formed virtually the same numbers of CFU-GM colonies and BFU-E colonies. These results suggest that BMMNCs from four of the MDS patients enrolled in this study had characteristics similar to AML BMMNCs, although they showed less proliferation than AML BMMNCs. We next examined the effect of NS-018 on CFU-GM colony formation. NS-018 treatment decreased the numbers of CFU-GM colonies from MDS-derived BMMNCs in a dose-dependent manner, and this effect was significantly more potent against MDS-derived than against normal cells (57.2% inhibition in MDS cells vs. 12.8% inhibition in normal cells at 0.5 mM NS-018; see Figure). These results indicate that NS-018 is preferentially efficacious in inhibiting CFU-GM formation from BMMNCs from high risk MDS. In addition, the level of phospho-STAT3 in MDS-derived colony-forming cells was twice as high as in colony-forming cells from normal BMMNCs, and 1.0 mM NS-018 completely suppressed the phosphorylation of STAT3 in CFU-GM colony-forming cells from MDS. Conclusion Our results show for the first time that a JAK2 inhibitor, NS-018, potently suppresses the formation of MDS colonies. NS-018 could be a new therapeutic option for high-risk MDS patients. Disclosures: Kodama: Nippon Shinyaku: Employment. Naito:Nippon Shinyaku: Employment. Nakaya:Nippon Shinyaku: Employment. Taniwaki:Novartis: Honoraria.

A novel SHP-1/Grb2–dependent mechanism of negative regulation of cytokine-receptor signaling: contribution of SHP-1 C-terminal tyrosines in cytokine signaling

Blood ◽  
2004 ◽  
Vol 103 (4) ◽  
pp. 1398-1407 ◽  
Author(s):  
Parham Minoo ◽  
Maryam Mohsen Zadeh ◽  
Robert Rottapel ◽  
Jean-Jacques Lebrun ◽  
Suhad Ali
Keyword(s):  
Adaptor Protein ◽  
Sh2 Domain ◽  
Janus Kinase ◽  
Cytokine Receptor ◽  
Negative Regulator ◽  
Cytokine Signaling ◽  
Binding Motif ◽  
Receptor Signaling ◽  
Tyrosine Residues ◽  
Receptor Complexes

Abstract SHP-1, an src homology 2 (SH2) domain containing protein tyrosine phosphatase, functions as a negative regulator of signaling downstream of cytokine receptors, receptor tyrosine kinases and receptor complexes of the immune system. Dephosphorylation of receptors and/or receptor-associated kinases has been described as the mechanism for the function of SHP-1. Here we demonstrate a novel mechanism by which SHP-1 down-regulates the Janus kinase–2 (Jak2)/signal transducer and activator of transcription-5 (Stat5) pathway downstream of the prolactin receptor (PRLR) and the erythropoietin receptor (EPOR) in a catalytic activity–independent manner. Structural/functional analysis of SHP-1 defined the C-terminal tyrosine residues (Y278, Y303, Y538, Y566) within growth factor receptor–bound protein 2 (Grb-2) binding motif to be responsible for delivering the inhibitory effects. Our results further indicate that these tyrosine residues, via recruitment of the adaptor protein Grb-2, are required for targeting the inhibitory protein suppressor of cytokine signaling–1 (SOCS-1) to Jak2 kinase. Finally, loss of SOCS-1 expression in SOCS-1–/– mouse embryonic fibroblast (MEF) cells led to attenuation in SHP-1 function to down-regulate PRL-induced Stat5 activation. All together, our results indicate that SHP-1 inhibits PRLR and EPOR signaling by recruitment and targeting of SOCS-1 to Jak2, highlighting a new mechanism of SHP-1 regulation of cytokine-receptor signaling.

New insights into the structure and function of the pseudokinase domain in JAK2

2013 ◽  
Vol 41 (4) ◽  
pp. 1002-1007 ◽  
Author(s):  
Olli Silvennoinen ◽  
Daniela Ungureanu ◽  
Yashavanthi Niranjan ◽  
Henrik Hammaren ◽  
Rajintha Bandaranayake ◽  
...  
Keyword(s):  
Myeloproliferative Neoplasms ◽  
Critical Role ◽  
Kinase Domain ◽  
Janus Kinase ◽  
Regulatory Function ◽  
Tyrosine Kinase Domain ◽  
Polycythaemia Vera ◽  
Underlying Mechanisms ◽  
Dynamics Simulations ◽  
High Level

JAK (Janus kinase) 2 plays a critical role in signal transduction through several cytokine receptors. JAKs contain a typical tyrosine kinase domain preceded by a pseudokinase [JH2 (JAK homology 2)] domain which has been considered to be catalytically inactive. Identification of activating mutations in the JH2 domain of JAK2 as the major cause for polycythaemia vera and other MPNs (myeloproliferative neoplasms) demonstrate the critical regulatory function for this domain, but the underlying mechanisms have remained elusive. We have performed biochemical and functional analysis on the JH2 domain of JAK2. The results indicate that JH2 functions as an active protein kinase and phosphorylates two residues in JAK2 (Ser523 and Tyr570) that have been shown previously to be negative regulatory sites for JAK2 activity. The crystal structure of the JAK2 JH2 domain provides an explanation for the functional findings and shows that JH2 adopts a prototypical kinase fold, but binds MgATP through a non-canonical mode. The structure of the most prevalent pathogenic JH2 mutation V617F shows a high level of similarity to wild-type JH2. The most notable structural deviation is observed in the N-lobe αC-helix. The structural and biochemical data together with MD (molecular dynamics) simulations show that the V617F mutation rigidifies the αC-helix, which results in hyperactivation of the JH1 domain through an as yet unidentified mechanism. These results provide structural and functional insights into the normal and pathogenic function of the JH2 domain of JAK2.

scholarly journals Crizotinib acts as ABL1 inhibitor combining ATP-binding with allosteric inhibition and is active against native BCR-ABL1 and its resistance and compound mutants BCR-ABL1T315I and BCR-ABL1T315I-E255K

2021 ◽  
Author(s):  
Afsar Ali Mian ◽  
Isabella Haberbosch ◽  
Hazem Khamaisie ◽  
Abed Agbarya ◽  
Larissa Pietsch ◽  
...  
Keyword(s):  
Binding Site ◽  
Kinase Inhibitors ◽  
Therapeutic Potential ◽  
Lymphoblastic Leukemia ◽  
Philadelphia Chromosome ◽  
Binding Pocket ◽  
Atp Binding ◽  
Atp Binding Site ◽  
Lung Cancer Patients

AbstractResistance remains the major clinical challenge for the therapy of Philadelphia chromosome–positive (Ph+) leukemia. With the exception of ponatinib, all approved tyrosine kinase inhibitors (TKIs) are unable to inhibit the common “gatekeeper” mutation T315I. Here we investigated the therapeutic potential of crizotinib, a TKI approved for targeting ALK and ROS1 in non-small cell lung cancer patients, which inhibited also the ABL1 kinase in cell-free systems, for the treatment of advanced and therapy-resistant Ph+ leukemia. By inhibiting the BCR-ABL1 kinase, crizotinib efficiently suppressed growth of Ph+ cells without affecting growth of Ph− cells. It was also active in Ph+ patient-derived long-term cultures (PD-LTCs) independently of the responsiveness/resistance to other TKIs. The efficacy of crizotinib was confirmed in vivo in syngeneic mouse models of BCR-ABL1- or BCR-ABL1T315I-driven chronic myeloid leukemia–like disease and in BCR-ABL1-driven acute lymphoblastic leukemia (ALL). Although crizotinib binds to the ATP-binding site, it also allosterically affected the myristol binding pocket, the binding site of GNF2 and asciminib (former ABL001). Therefore, crizotinib has a seemingly unique double mechanism of action, on the ATP-binding site and on the myristoylation binding pocket. These findings strongly suggest the clinical evaluation of crizotinib for the treatment of advanced and therapy-resistant Ph+ leukemia.

scholarly journals A Molecular Modeling Approach to Identify Potential Antileishmanial Compounds Against the Cell Division Cycle (cdc)-2-Related Kinase 12 (CRK12) Receptor of Leishmania donovani

Biomolecules ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 458
Author(s):  
Emmanuel Broni ◽  
Samuel K. Kwofie ◽  
Seth O. Asiedu ◽  
Whelton A. Miller ◽  
Michael D. Wilson
Keyword(s):  
Natural Products ◽  
Cell Division ◽  
Leishmania Donovani ◽  
Therapeutic Potential ◽  
Neglected Tropical Diseases ◽  
Binding Pocket ◽  
Cell Division Cycle ◽  
World Health ◽  
Atp Binding ◽  
African Flora

The huge burden of leishmaniasis caused by the trypanosomatid protozoan parasite Leishmania is well known. This illness was included in the list of neglected tropical diseases targeted for elimination by the World Health Organization. However, the increasing evidence of resistance to existing antimonial drugs has made the eradication of the disease difficult to achieve, thus warranting the search for new drug targets. We report here studies that used computational methods to identify inhibitors of receptors from natural products. The cell division cycle-2-related kinase 12 (CRK12) receptor is a plausible drug target against Leishmania donovani. This study modelled the 3D molecular structure of the L. donovani CRK12 (LdCRK12) and screened for small molecules with potential inhibitory activity from African flora. An integrated library of 7722 African natural product-derived compounds and known inhibitors were screened against the LdCRK12 using AutoDock Vina after performing energy minimization with GROMACS 2018. Four natural products, namely sesamin (NANPDB1649), methyl ellagic acid (NANPDB1406), stylopine (NANPDB2581), and sennecicannabine (NANPDB6446) were found to be potential LdCRK12 inhibitory molecules. The molecular docking studies revealed two compounds NANPDB1406 and NANPDB2581 with binding affinities of −9.5 and −9.2 kcal/mol, respectively, against LdCRK12 which were higher than those of the known inhibitors and drugs, including GSK3186899, amphotericin B, miltefosine, and paromomycin. All the four compounds were predicted to have inhibitory constant (Ki) values ranging from 0.108 to 0.587 μM. NANPDB2581, NANPDB1649 and NANPDB1406 were also predicted as antileishmanial with Pa and Pi values of 0.415 and 0.043, 0.391 and 0.052, and 0.351 and 0.071, respectively. Molecular dynamics simulations coupled with molecular mechanics Poisson–Boltzmann surface area (MM/PBSA) computations reinforced their good binding mechanisms. Most compounds were observed to bind in the ATP binding pocket of the kinase domain. Lys488 was predicted as a key residue critical for ligand binding in the ATP binding pocket of the LdCRK12. The molecules were pharmacologically profiled as druglike with inconsequential toxicity. The identified molecules have scaffolds that could form the backbone for fragment-based drug design of novel leishmanicides but warrant further studies to evaluate their therapeutic potential.

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