scholarly journals Crystal structure of the Jak3 kinase domain in complex with a staurosporine analog

Blood ◽  
2005 ◽  
Vol 106 (3) ◽  
pp. 996-1002 ◽  
Author(s):  
Titus J. Boggon ◽  
Yiqun Li ◽  
Paul W. Manley ◽  
Michael J. Eck
Keyword(s):  
Crystal Structure ◽  
Tyrosine Kinases ◽  
Severe Combined Immunodeficiency ◽  
Kinase Domain ◽  
Janus Kinase ◽  
Cytokine Signaling ◽  
Activation Loop ◽  
Gamma Chain ◽  
The Common ◽  
Nonreceptor Tyrosine Kinases

AbstractJak (Janus kinase) family nonreceptor tyrosine kinases are central mediators of cytokine signaling. The Jak kinases exhibit distinct cytokine receptor association profiles and so transduce different signals. Jak3 expression is limited to the immune system, where it plays a key role in signal transduction from cytokine receptors containing the common gamma-chain, γc. Patients unable to signal via γc present with severe combined immunodeficiency (SCID). The finding that Jak3 mutations result in SCID has made it a target for development of lymphocyte-specific immunosuppressants. Here, we present the crystal structure of the Jak3 kinase domain in complex with staurosporine analog AFN941. The kinase domain is in the active conformation, with both activation loop tyrosine residues phosphorylated. The phosphate group on pTyr981 in the activation loop is in part coordinated by an arginine residue in the regulatory C-helix, suggesting a direct mechanism by which the active position of the C-helix is induced by phosphorylation of the activation loop. Such a direct coupling has not been previously observed in tyrosine kinases and may be unique to Jak kinases. The crystal structure provides a detailed view of the Jak3 active site and will facilitate computational and structure-directed approaches to development of Jak3-specific inhibitors.

Jak3 Kinase Domain Crystal Structures and Implications for Jak-Specific Drug Design.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 69-69 ◽  
Author(s):  
Titus J. Boggon
Keyword(s):  
Crystal Structure ◽  
Drug Design ◽  
Crystal Structures ◽  
Small Molecule ◽  
Tyrosine Kinases ◽  
Severe Combined Immunodeficiency ◽  
Kinase Domain ◽  
Crystal Forms ◽  
Jak Kinase ◽  
Catalytic Cleft

Abstract Janus (Jak) family non-receptor tyrosine kinases are critical for appropriate signaling of many growth factors and cytokines. The four vertebrate Jak kinase family members demonstrate differential receptor cytoplasmic tail binding associations and transduce discrete signals on extracellular binding of ligand to the transmembrane cytokine or growth factor receptor. On ligand binding, a rapid tyrosine phosphorylation mediated signaling cascade is initiated, culminating in translocation of cytosolic latent transcription factors, signal transducer and activator of transcription (Stat) proteins, to the nucleus and targeted activation of transcription. Dysregulation of this Jak-mediated signaling pathway is documented in a number of hematological diseases: Improper upregulation of Jak activity is seen in certain hematological malignancies [1] and inability to appropriately transduce signals from the common gamma chain, γc, through Jak3 is responsible for approximately 60% of human severe combined immunodeficiency cases [2]. In addition, Jak2 point mutation V617F is frequently documented in myeloproliferative disorders including polycythemia vera; this activating mutation may disrupt an autoinhibited conformation [3]. Therapies targeting restraint of Jak family tyrosine kinase activity may be useful for treating inappropriate activation of Jak signaling cascades or for suppressing the immune response. Advances towards structure-directed drug design of Jak-specific inhibitors were made recently with solution of the Jak3 kinase domain X-ray crystal structure [4], representing the first three-dimensional structural data for any portion of the Jak family of tyrosine kinases. Here three further crystal structures of the kinase domain of Jak3 are presented: an improved resolution co-crystal structure with staurosporine analog AFN-941 and two crystal forms of Jak3 kinase domain in complex with the kinase inhibitor small molecule compound QAD-409. Comparisons between these three solved Jak3 kinase domain crystal structures illustrate conformational flexibility between the kinase domain lobes and in the area of the catalytic cleft. Further structure analysis is also presented documenting in silico modeling of the binding of small molecule CP-690,550 [5] to the different Jak3 kinase domain crystal forms. Potential binding conformations of this inhibitor to the Jak3 kinase domain are suggested with one highly scored binding conformation predicted for all crystal forms. The crystal structures and modeling studies presented further define the extent of the Jak kinase catalytic cleft, demonstrate conformational plasticity in the active conformation Jak3 kinase domain and will aid the design of higher specificity Jak inhibitors.

The Src family kinase Fgr is a transforming oncoprotein that functions independently of SH3-SH2 domain regulation

2018 ◽  
Vol 11 (553) ◽  
pp. eaat5916 ◽  
Author(s):  
Kexin Shen ◽  
Jamie A. Moroco ◽  
Ravi K. Patel ◽  
Haibin Shi ◽  
John R. Engen ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Colony Formation ◽  
Family Members ◽  
Cellular Transformation ◽  
Soft Agar ◽  
Kinase Domain ◽  
Sh2 Domain ◽  
Mass Spectrometry Data ◽  
Activation Loop ◽  
Exchange Mass Spectrometry

Fgr is a member of the Src family of nonreceptor tyrosine kinases, which are overexpressed and constitutively active in many human cancers. Fgr expression is restricted to myeloid hematopoietic cells and is markedly increased in a subset of bone marrow samples from patients with acute myeloid leukemia (AML). Here, we investigated the oncogenic potential of Fgr using Rat-2 fibroblasts that do not express the kinase. Expression of either wild-type or regulatory tail-mutant constructs of Fgr promoted cellular transformation (inferred from colony formation in soft agar), which was accompanied by phosphorylation of the Fgr activation loop, suggesting that the kinase domain of Fgr functions independently of regulation by its noncatalytic SH3-SH2 region. Unlike other family members, recombinant Fgr was not activated by SH3-SH2 domain ligands. However, hydrogen-deuterium exchange mass spectrometry data suggested that the regulatory SH3 and SH2 domains packed against the back of the kinase domain in a Src-like manner. Sequence alignment showed that the activation loop of Fgr was distinct from that of all other Src family members, with proline rather than alanine at the +2 position relative to the activation loop tyrosine. Substitution of the activation loop of Fgr with the sequence from Src partially inhibited kinase activity and suppressed colony formation. Last, Fgr expression enhanced the sensitivity of human myeloid progenitor cells to the cytokine GM-CSF. Because its kinase domain is not sensitive to SH3-SH2–mediated control, simple overexpression of Fgr without mutation may contribute to oncogenic transformation in AML and other blood cancers.

scholarly journals Two Distinct Phosphorylation Pathways Have Additive Effects on Abl Family Kinase Activation

2003 ◽  
Vol 23 (11) ◽  
pp. 3884-3896 ◽  
Author(s):  
Keith Q. Tanis ◽  
Darren Veach ◽  
Henry S. Duewel ◽  
William G. Bornmann ◽  
Anthony J. Koleske
Keyword(s):  
Tyrosine Kinases ◽  
Kinase Activity ◽  
Intramolecular Interactions ◽  
Activation Loop ◽  
Additive Effects ◽  
Nonreceptor Tyrosine Kinase ◽  
Kinase Activation ◽  
Surface Receptors ◽  
Nonreceptor Tyrosine Kinases ◽  
Stimulation Of

ABSTRACT The activities of the related Abl and Arg nonreceptor tyrosine kinases are kept under tight control in cells, but exposure to several different stimuli results in a two- to fivefold stimulation of kinase activity. Following the breakdown of inhibitory intramolecular interactions, Abl activation requires phosphorylation on several tyrosine residues, including a tyrosine in its activation loop. These activating phosphorylations have been proposed to occur either through autophosphorylation by Abl in trans or through phosphorylation of Abl by the Src nonreceptor tyrosine kinase. We show here that these two pathways mediate phosphorylation at distinct sites in Abl and Arg and have additive effects on Abl and Arg kinase activation. Abl and Arg autophosphorylate at several sites outside the activation loop, leading to 5.2- and 6.2-fold increases in kinase activity, respectively. We also find that the Src family kinase Hck phosphorylates the Abl and Arg activation loops, leading to an additional twofold stimulation of kinase activity. The autoactivation pathway may allow Abl family kinases to integrate or amplify cues relayed by Src family kinases from cell surface receptors.

Structural Analysis of Janus Kinases.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3863-3863
Author(s):  
Titus J. Boggon ◽  
Yiqun Li ◽  
Michael J. Eck
Keyword(s):  
Structural Information ◽  
Severe Combined Immunodeficiency ◽  
Interleukin 2 ◽  
Selective Inhibition ◽  
Kinase Domain ◽  
Janus Kinase ◽  
Catalytically Active ◽  
Carboxy Terminal ◽  
Structural Insights ◽  
Kinase A

Abstract Janus Kinase 3 (Jak3) plays an essential role in hematopoietic signaling. Primarily expressed in B-, T- and Natural killer cells, it is activated through the γc chain of interleukin-2 like cytokine receptors (IL-2, -4, -7, -9, -15, -21). Deficiency of catalytically active Jak3 or disruption of the Jak3:IL-2γc interaction results in severe combined immunodeficiency (SCID). Jak3-deficient humans demonstrate defects restricted to the immune system, suggesting that selective inhibition of Jak3 catalytic activity or interruption of the Jak3:IL-2γc interaction are potentially exploitable strategies to achieve immunosuppression. Jak kinases contain four defined regions; a catalytically active carboxy-terminal kinase, a pseudo-kinase, a SH2-like region and a N-terminal Ferm domain. To date, no direct structural information has been reported for portions of any of the Jak family kinases. Structural studies are underway to define crystallographically the kinase domain of Jak3 and the Jak3-Ferm:IL-2γc interaction. Structural insights into the mechanism of Jak activation and routes to specific inhibition will be discussed.

Osmotic shrinkage elicits FAK- and Src phosphorylation and Src-dependent NKCC1 activation in NIH3T3 cells

2015 ◽  
Vol 308 (2) ◽  
pp. C101-C110 ◽  
Author(s):  
Line Jee Hartmann Rasmussen ◽  
Helene Steenkær Holm Müller ◽  
Bente Jørgensen ◽  
Stine Falsig Pedersen ◽  
Else Kay Hoffmann
Keyword(s):  
Focal Adhesion ◽  
Tyrosine Kinases ◽  
Volume Regulation ◽  
Mammalian Cells ◽  
Myosin Light Chain ◽  
Janus Kinase ◽  
Nih3t3 Cells ◽  
Src Inhibitor ◽  
Nonreceptor Tyrosine Kinases

The mechanisms linking cell volume sensing to volume regulation in mammalian cells remain incompletely understood. Here, we test the hypothesis that activation of nonreceptor tyrosine kinases Src, focal adhesion kinase (FAK), and Janus kinase-2 (Jak2) occurs after osmotic shrinkage of NIH3T3 fibroblasts and contributes to volume regulation by activation of NKCC1. FAK phosphorylation at Tyr397, Tyr576/577, and Tyr861 was increased rapidly after exposure to hypertonic (575 mOsm) saline, peaking after 10 (Tyr397, Tyr576/577) and 10–30 min (Tyr861). Shrinkage-induced Src family kinase autophosphorylation (pTyr416-Src) was induced after 2–10 min, and immunoprecipitation indicated that this reflected phosphorylation of Src itself, rather than Fyn and Yes. Phosphorylated Src and FAK partly colocalized with vinculin, a focal adhesion marker, after hypertonic shrinkage. The Src inhibitor pyrazolopyrimidine-2 (PP2, 10 μM) essentially abolished shrinkage-induced FAK phosphorylation at Tyr576/577 and Tyr861, yet not at Tyr397, and inhibited shrinkage-induced NKCC1 activity by ∼50%. The FAK inhibitor PF-573,228 augmented shrinkage-induced Src phosphorylation, and inhibited shrinkage-induced NKCC1 activity by ∼15%. The apparent role of Src in NKCC1 activation did not reflect phosphorylation of myosin light chain kinase (MLC), which was unaffected by shrinkage and by PP2, but may involve Jak2, a known target of Src, which was rapidly activated by osmotic shrinkage and inhibited by PP2. Collectively, our findings suggest a major role for Src and possibly the Jak2 axis in shrinkage-activation of NKCC1 in NIH3T3 cells, whereas no evidence was found for major roles for FAK and MLC in this process.

scholarly journals Gene therapy improves immune function in preadolescents with X-linked severe combined immunodeficiency

Blood ◽  
2007 ◽  
Vol 110 (1) ◽  
pp. 67-73 ◽  
Author(s):  
Javier Chinen ◽  
Joie Davis ◽  
Suk See De Ravin ◽  
Beverly N. Hay ◽  
Amy P. Hsu ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Cell Function ◽  
Severe Combined Immunodeficiency ◽  
Marrow Transplant ◽  
Salvage Treatment ◽  
Combined Immunodeficiency ◽  
Gamma Chain ◽  
Gene Encoding ◽  
Il2rg Gene ◽  
The Common

Retroviral gene therapy can restore immunity to infants with X-linked severe combined immunodeficiency (XSCID) caused by mutations in the IL2RG gene encoding the common gamma chain (γc) of receptors for interleukins 2 (IL-2), −4, −7, −9, −15, and −21. We investigated the safety and efficacy of gene therapy as salvage treatment for older XSCID children with inadequate immune reconstitution despite prior bone marrow transplant from a parent. Subjects received retrovirus-transduced autologous peripherally mobilized CD34+ hematopoietic cells. T-cell function significantly improved in the youngest subject (age 10 years), and multilineage retroviral marking occurred in all 3 children.

scholarly journals Complex Effects of Naturally Occurring Mutations in the JAK3 Pseudokinase Domain: Evidence for Interactions between the Kinase and Pseudokinase Domains

2000 ◽  
Vol 20 (3) ◽  
pp. 947-956 ◽  
Author(s):  
Min Chen ◽  
Alan Cheng ◽  
Fabio Candotti ◽  
Yong-Jie Zhou ◽  
Anka Hymel ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Tyrosine Kinases ◽  
Kinase Activity ◽  
Catalytic Domain ◽  
Intramolecular Interaction ◽  
Severe Combined Immunodeficiency ◽  
Kinase Domain ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT The structure of Janus kinases (JAKs) is unique among protein tyrosine kinases in having tandem, nonidentical kinase and pseudokinase domains. Despite its conservation in evolution, however, the function of the pseudokinase domain remains poorly understood. Lack of JAK3 expression results in severe combined immunodeficiency (SCID). In this study, we analyze two SCID patients with mutations in the JAK3 pseudokinase domain, which allows for protein expression but disrupts the regulation of the kinase activity. Specifically, these mutant forms of JAK3 had undetectable kinase activity in vitro but were hyperphosphorylated both in patients' Epstein-Barr virus-transformed B cells and when overexpressed in COS7 cells. Moreover, reconstitution of cells with these mutants demonstrated that, although they were constitutively phosphorylated basally, they were unable to transmit cytokine-dependent signals. Further analysis showed that the isolated catalytic domain of JAK3 was functional whereas either the addition of the pseudokinase domain or its deletion from the full-length molecule reduced catalytic activity. Through coimmunoprecipitation of the isolated pseudokinase domain with the isolated catalytic domain, we provide the first evidence that these two domains interact. Furthermore, whereas the wild-type pseudokinase domain modestly inhibited kinase domain-mediated STAT5 phosphorylation, the patient-derived mutants markedly inhibited this phosphorylation. We thus conclude that the JAK3 pseudokinase domain is essential for JAK3 function by regulating its catalytic activity and autophosphorylation. We propose a model in which this occurs via intramolecular interaction with the kinase domain and that increased inhibition of kinase activity by the pseudokinase domain likely contributes to the disease pathogenesis in these two patients.

scholarly journals Differences in the dynamics of the tandem-SH2 modules of the Syk and ZAP-70 tyrosine kinases

2021 ◽  
Author(s):  
Helen T. Hobbs ◽  
Neel H. Shah ◽  
Jean M. Badroos ◽  
Christine L. Gee ◽  
Susan Marqusee ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Tyrosine Kinases ◽  
Bound State ◽  
Kinase Domain ◽  
Sh2 Domain ◽  
Hydrogen Deuterium Exchange ◽  
Inactive Conformation ◽  
Downstream Signaling ◽  
Hydrogen Deuterium ◽  
Dynamics Simulations

The catalytic activity of Syk-family tyrosine kinases is regulated by a tandem-SH2 module (tSH2 module). In the autoinhibited state, this module adopts a conformation which stabilizes an inactive conformation of the kinase domain. The binding of the tSH2 module to doubly-phosphorylated tyrosine-containing motifs necessitates a conformational change, thereby relieving kinase inhibition and promoting activation. We determined the crystal structure of the isolated tSH2 module of Syk and find, in contrast to ZAP-70, that its conformation more closely resembles that of the peptide-bound state, rather than the autoinhibited state. Hydrogen-deuterium exchange by mass spectrometry, as well as molecular dynamics simulations, reveal that the dynamics of the tSH2 modules of Syk and ZAP-70 differ, with most of these differences occurring in the C-terminal SH2 domain. Our data suggest that the conformational landscapes of the tSH2 modules in Syk and ZAP-70 have been tuned differently, such that the auto-inhibited conformation of the Syk tSH2 module is less stable. This feature of Syk likely contributes to its ability to more readily escape autoinhibition when compared to ZAP-70, consistent with tighter control of downstream signaling pathways in T cells.

scholarly journals Abl2 is recruited to ventral actin waves through cytoskeletal interactions to promote lamellipodium extension

2018 ◽  
Vol 29 (23) ◽  
pp. 2863-2873 ◽  
Author(s):  
Ke Zhang ◽  
Wanqing Lyu ◽  
Ji Yu ◽  
Anthony J. Koleske
Keyword(s):  
Tyrosine Kinases ◽  
Total Internal Reflection ◽  
Cell Shape ◽  
Kinase Domain ◽  
Outer Edge ◽  
Spatiotemporal Resolution ◽  
Actin Waves ◽  
And Migration ◽  
Necessary And Sufficient ◽  
Nonreceptor Tyrosine Kinases

Abl family nonreceptor tyrosine kinases regulate changes in cell shape and migration. Abl2 localizes to dynamic actin-rich protrusions, such as lamellipodia in fibroblasts and dendritic spines in neurons. Abl2 interactions with cortactin, an actin filament stabilizer, are crucial for the formation and stability of actin-rich structures, but Abl2:cortactin-positive structures have not been characterized with high spatiotemporal resolution in cells. Using total internal reflection fluorescence microscopy, we demonstrate that Abl2 colocalizes with cortactin at wave-like structures within lamellum and lamellipodium tips. Abl2 and cortactin within waves are focal and transient, extend to the outer edge of lamella, and serve as the base for lamellipodia protrusions. Abl2-positive foci colocalize with integrin β3 and paxillin, adhesive markers of the lamellum–lamellipodium interface. Cortactin-positive waves still form in Abl2 knockout cells, but the lamellipodium size is significantly reduced. This deficiency is restored following Abl2 reexpression. Complementation analyses revealed that the Abl2 C-terminal half, which contains domains that bind actin and microtubules, is necessary and sufficient for recruitment to the wave-like structures and to support normal lamellipodium size, while the kinase domain–containing N-terminal half does not impact lamellipodium size. Together, this work demonstrates that Abl2 is recruited with cortactin to actin waves through cytoskeletal interactions to promote lamellipodium extension.

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