Identification of imidazo[1,2-<i>b</i>]pyridazine TYK2 pseudokinase ligands as potent and selective allosteric inhibitors of TYK2 signalling

Moslin, Ryan; Gardner, Daniel S.; Santella, Joseph B.; Zhang, Y.; Duncia, John V.; Liu, C.; Lin, James; Tokarski, John S.; Strnad, Joann; Pedicord, Donna L.; Chen, J.; Blat, Yuval; Zupa-Fernandez, Adriana; Cheng, Lihong; Sun, Huadong; Chaudhry, Charu; Huang, Christine; D’Arienzo, Celia; Sack, John S.; Muckelbauer, J.K.; Chang, ChiehYing Y.; Tredup, Jeffrey; Xie, Dan; Aranı́bar, Nelly; Burke, James R.; Carter, P. H.; Weinstein, David

doi:10.1039/c6md00560h

Cited by 44 publications

(73 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…To what extent a small molecule could reshape the ATP binding pocket in JH2 is also a question, given that the apo and ATP-bound JH2 structures are very similar ( 26 ). However, recent studies of compounds that bind in the ATP binding pocket of TYK2 JH2 and inhibit TYK2 signaling provide reason for optimism ( 45 , 46 ). One senses that a wealth of structural data for JAKs will come to light in the next few years, with implications for novel therapeutic modalities.…”

Section: Prospects For a Mutant Jak2 Inhibitormentioning

confidence: 99%

Mechanistic Insights into Regulation of JAK2 Tyrosine Kinase

Hubbard

2018

Front. Endocrinol.

View full text Add to dashboard Cite

JAK2 is a member of the Janus kinase (JAKs) family of non-receptor protein tyrosine kinases, which includes JAK1–3 and TYK2. JAKs serve as the cytoplasmic signaling components of cytokine receptors and are activated through cytokine-mediated trans-phosphorylation, which leads to receptor phosphorylation and recruitment and phosphorylation of signal transducer and activator of transcription (STAT) proteins. JAKs are unique among tyrosine kinases in that they possess a pseudokinase domain, which is just upstream of the C-terminal tyrosine kinase domain. A wealth of biochemical and clinical data have established that the pseudokinase domain of JAKs is crucial for maintaining a low basal (absence of cytokine) level of tyrosine kinase activity. In particular, gain-of-function mutations in the JAK genes, most frequently, V617F in the pseudokinase domain of JAK2, have been mapped in patients with blood disorders, including myeloproliferative neoplasms and leukemias. Recent structural and biochemical studies have begun to decipher the molecular mechanisms that maintain the basal, low-activity state of JAKs and that, via mutation, lead to constitutive activity and disease. This review will examine these mechanisms and describe how this knowledge could potentially inform drug development efforts aimed at obtaining a mutant (V617F)-selective inhibitor of JAK2.

show abstract

Section: Prospects For a Mutant Jak2 Inhibitormentioning

confidence: 99%

Mechanistic Insights into Regulation of JAK2 Tyrosine Kinase

Hubbard

2018

Front. Endocrinol.

View full text Add to dashboard Cite

show abstract

“…Currently there are three JAK JH1-targeted inhibitors in clinical use, but recently targeting JAK JH2s with small molecular compounds has gained interest as a potential treatment for constitutively active cytokine signaling [10,23,24]. The unique mode of ATP binding in JH2 may allow increased specificity over other eukaryotic protein kinases [25].…”

Section: Introductionmentioning

confidence: 99%

Characterization of JAK1 Pseudokinase Domain in Cytokine Signaling

Raivola

Haikarainen

Silvennoinen

2019

Cancers

View full text Add to dashboard Cite

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.

show abstract

“…This closely resembled the binding modes described for 8-amino-imidazo[1,2- b ]pyridazines in other kinases. 28,29,37,38 An additional hydrogen bond (2.8 Å) was observed between the indazole NH and Y628, presumably contributing to stabilizing the tyrosine “down” conformation. The indazole occupied a hydrophobic pocket formed by the gatekeeper residue I642, F712 of the DFG motif, F725 from the activation loop, and the catalytic lysine K599.…”

Section: Resultsmentioning

confidence: 99%

Binding to an Unusual Inactive Kinase Conformation by Highly Selective Inhibitors of Inositol-Requiring Enzyme 1α Kinase-Endoribonuclease

et al. 2019

View full text Add to dashboard Cite

A series of imidazo[1,2- b ]pyridazin-8-amine kinase inhibitors were discovered to allosterically inhibit the endoribonuclease function of the dual kinase-endoribonuclease inositol-requiring enzyme 1α (IRE1α), a key component of the unfolded protein response in mammalian cells and a potential drug target in multiple human diseases. Inhibitor optimization gave compounds with high kinome selectivity that prevented endoplasmic reticulum stress-induced IRE1α oligomerization and phosphorylation, and inhibited endoribonuclease activity in human cells. X-ray crystallography showed the inhibitors to bind to a previously unreported and unusually disordered conformation of the IRE1α kinase domain that would be incompatible with back-to-back dimerization of the IRE1α protein and activation of the endoribonuclease function. These findings increase the repertoire of known IRE1α protein conformations and can guide the discovery of highly selective ligands for the IRE1α kinase site that allosterically inhibit the endoribonuclease.

show abstract

Identification of imidazo[1,2-b]pyridazine TYK2 pseudokinase ligands as potent and selective allosteric inhibitors of TYK2 signalling

Cited by 44 publications

References 25 publications

Mechanistic Insights into Regulation of JAK2 Tyrosine Kinase

Mechanistic Insights into Regulation of JAK2 Tyrosine Kinase

Characterization of JAK1 Pseudokinase Domain in Cytokine Signaling

Binding to an Unusual Inactive Kinase Conformation by Highly Selective Inhibitors of Inositol-Requiring Enzyme 1α Kinase-Endoribonuclease

Contact Info

Product

Resources

About