This review article illustrates the growing use of azaindole derivatives as kinase inhibitors and their contribution to drug discovery and innovation. The different protein kinases which have served as targets and the known molecules which have emerged from medicinal chemistry and Fragment-Based Drug Discovery (FBDD) programs are presented. The various synthetic routes used to access these compounds and the chemical pathways leading to their synthesis are also discussed. An analysis of their mode of binding based on X-ray crystallography data gives structural insights for the design of more potent and selective inhibitors.

https://www.mdpi.com/1420-3049/19/12/19935/pdf

The azaindole framework in the design of kinase inhibitors.

Recent advances in the synthesis and properties of 4-, 5-, 6- or 7-azaindoles

The sequence of events that initiates T cell signaling is dictated by the specificities and order of activation of the tyrosine kinases that signal downstream of the T cell receptor. Using a platform that combines exhaustive point-mutagenesis of peptide substrates, bacterial surface-display, cell sorting, and deep sequencing, we have defined the specificities of the first two kinases in this pathway, Lck and ZAP-70, for the T cell receptor ζ chain and the scaffold proteins LAT and SLP-76. We find that ZAP-70 selects its substrates by utilizing an electrostatic mechanism that excludes substrates with positively-charged residues and favors LAT and SLP-76 phosphosites that are surrounded by negatively-charged residues. This mechanism prevents ZAP-70 from phosphorylating its own activation loop, thereby enforcing its strict dependence on Lck for activation. The sequence features in ZAP-70, LAT, and SLP-76 that underlie electrostatic selectivity likely contribute to the specific response of T cells to foreign antigens.

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An electrostatic selection mechanism controls sequential kinase signaling downstream of the T cell receptor

Methods of inhibiting the replication of influenza viruses in a biological sample or patient, of reducing the amount of influenza viruses in a biological sample or patient, and of treating influenza in a patient, comprises administering to said biological sample or patient an effective amount of a compound represented by Structural Formula (I): or a pharmaceutically acceptable salt thereof, wherein the values of Structural Formula (I) are as described herein. A compound is represented by Structural Formula (I) or a pharmaceutically acceptable salt thereof, wherein the values of Structural Formula (I) are as described herein. A pharmaceutical composition comprises an effective amount of such a compound or pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier, adjuvant or vehicle.

Inhibitors of influenza viruses replication

Protein kinase autophosphorylation is a common regulatory mechanism in cell signaling pathways. Crystal structures of several homomeric protein kinase complexes have a serine, threonine, or tyrosine autophosphorylation site of one kinase monomer located in the active site of another monomer, a structural complex that we call an “autophosphorylation complex.” We developed and applied a structural bioinformatics method to identify all such autophosphorylation complexes in x-ray crystallographic structures in the Protein Data Bank (PDB). We identified 15 autophosphorylation complexes in the PDB, of which five complexes had not previously been described in the publications describing the crystal structures. These five complexes consist of tyrosine residues in the N-terminal juxtamembrane regions of colony-stimulating factor 1 receptor (CSF1R, Tyr 561 ) and ephrin receptor A2 (EPHA2, Tyr 594 ), tyrosine residues in the activation loops of the SRC kinase family member LCK (Tyr 394 ) and insulin-like growth factor 1 receptor (IGF1R, Tyr 1166 ), and a serine in a nuclear localization signal region of CDC-like kinase 2 (CLK2, Ser 142 ). Mutations in the complex interface may alter autophosphorylation activity and contribute to disease; therefore, we mutated residues in the autophosphorylation complex interface of LCK and found that two mutations impaired autophosphorylation (T445V and N446A) and mutation of Pro 447 to Ala, Gly, or Leu increased autophosphorylation. The identified autophosphorylation sites are conserved in many kinases, suggesting that, by homology, these complexes may provide insight into autophosphorylation complex interfaces of kinases that are relevant drug targets.

Identifying three-dimensional structures of autophosphorylation complexes in crystals of protein kinases.

From an azaindole lead, identified in high throughput screen, a series of potent bis-azaindole inhibitors of IGF1-R have been synthesized using rational drug design and SAR based on a in silico binding mode hypothesis. Although the resulting compounds produced the expected improved potency, the model was not validated by the co-crystallization experiments with IGF1-R.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1747-0285.2010.00991.x

François Bernard

Papers

Design of potent IGF1-R inhibitors related to bis-azaindoles.