Characterization of 2,4-Dianilinopyrimidines Against Five Kinases PfARK1, PfARK3, PfNEK3, PfPK9, and PfPKB.

kinases are increasingly recognized as potential novel antiplasmodial targets for the treatment of malaria, but only a small subset of these kinases have had structure-activity relationship (SAR) campaigns reported. Herein we report the discovery of CZC-54252 () as an inhibitor of five kinases PfARK1, PfARK3, PfNEK3, PfPK9, and PfPKB. 39 analogues were evaluated against all five kinases to establish SAR at three regions of the kinase active site.

SGC-CLK-1: A chemical probe for the Cdc2-like kinases CLK1, CLK2, and CLK4.

Small molecule modulators are important tools to study both basic biology and the complex signaling of protein kinases. The cdc2-like kinases (CLK) are a family of four kinases that have garnered recent interest for their involvement in a diverse set of diseases such as neurodegeneration, autoimmunity, and many cancers. Targeted medicinal chemistry around a CLK inhibitor hit identified through screening of a kinase inhibitor set against a large panel of kinases allowed us to identify a potent and selective inhibitor of CLK1, 2, and 4.

GPR114/ADGRG5 is activated by its tethered peptide agonist because it is a cleaved adhesion GPCR.

Family B2 or adhesion G protein-coupled receptors (AGPCRs) are distinguished by variable extracellular regions that contain a modular protease, termed the GPCR autoproteolysis-inducing domain that self-cleaves the receptor into an N-terminal fragment (NTF) and a C-terminal fragment (CTF), or seven transmembrane domain (7TM). The NTF and CTF remain bound after cleavage through noncovalent interactions. NTF binding to a ligand(s) presented by nearby cells, or the extracellular matrix anchors the NTF, such that cell movement generates force to induce NTF/CTF dissociation and expose the AGPCR tethered peptide agonist.

Structures of Ric-8B in complex with Gα protein folding clients reveal isoform specificity mechanisms.

Mammalian Ric-8 proteins act as chaperones to regulate the cellular abundance of heterotrimeric G protein α subunits. The Ric-8A isoform chaperones Gαi/o, Gα12/13, and Gαq/11 subunits, while Ric-8B acts on Gαs/olf subunits. Here, we determined cryoelectron microscopy (cryo-EM) structures of Ric-8B in complex with Gαs and Gαolf, revealing isoform differences in the relative positioning and contacts between the C-terminal α5 helix of Gα within the concave pocket formed by Ric-8 α-helical repeat elements.

Discovery of potent Plasmodium falciparum protein kinase 6 (PfPK6) inhibitors with a type II inhibitor pharmacophore.

Malaria is a devastating disease that causes significant global morbidity and mortality. The rise of drug resistance against artemisinin-based combination therapy demonstrates the necessity to develop alternative antimalarials with novel mechanisms of action. We report the discovery of Ki8751 as an inhibitor of essential kinase PfPK6.

Identification of Novel 2,4,5-Trisubstituted Pyrimidines as Potent Dual Inhibitors of Plasmodial GSK3/PK6 with Activity against Blood Stage Parasites In Vitro.

Essential plasmodial kinases GSK3 and PK6 are considered novel drug targets to combat rising resistance to traditional antimalarial therapy. Herein, we report the discovery of as a dual GSK3/PK6 inhibitor active against blood stage 3D7 parasites. To establish structure-activity relationships for PK6 and GSK3, 52 analogues were synthesized and assessed for the inhibition of GSK3 and PK6, with potent inhibitors further assessed for activity against blood and liver stage parasites.

The tethered peptide activation mechanism of adhesion GPCRs.

Adhesion G-protein-coupled receptors (aGPCRs) are characterized by the presence of auto-proteolysing extracellular regions that are involved in cell-cell and cell-extracellular matrix interactions. Self cleavage within the aGPCR auto-proteolysis-inducing (GAIN) domain produces two protomers-N-terminal and C-terminal fragments-that remain non-covalently attached after receptors reach the cell surface. Upon dissociation of the N-terminal fragment, the C-terminus of the GAIN domain acts as a tethered agonist (TA) peptide to activate the seven-transmembrane domain with a mechanism that has been poorly understood.

Identification of 4-Anilinoquin(az)oline as a Cell-Active Protein Kinase Novel 3 (PKN3) Inhibitor Chemotype.

Deep annotation of a library of 4-anilinoquin(az)olines led to the identification of 7-iodo-N-(3,4,5-trimethoxyphenyl)quinolin-4-amine 16 as a potent inhibitor (IC =14 nM) of Protein Kinase Novel 3 (PKN3) with micromolar activity in cells. Compound 16 is a potential tool compound to study the cell biology of PKN3 and its role in pancreatic and prostate cancer and T-cell acute lymphoblastic leukemia. These 4-anilinoquin(az)olines may also be useful tools to uncover the therapeutic potential of PKN3 inhibition in a broad range of diseases.

A Chemical Probe for Dark Kinase STK17B Derives Its Potency and High Selectivity through a Unique P-Loop Conformation.

STK17B is a member of the death-associated protein kinase family and has been genetically linked to the development of diverse diseases. However, the role of STK17B in normal and disease pathology is poorly defined. Here, we present the discovery of thieno[3,2-d] pyrimidine (), a high-quality chemical probe for this understudied "dark" kinase.

Selective Proteolysis to Study the Global Conformation and Regulatory Mechanisms of c-Src Kinase.

Protein kinase pathways are traditionally mapped by monitoring downstream phosphorylation. Meanwhile, the noncatalytic functions of protein kinases remain under-appreciated as critical components of kinase signaling. c-Src is a protein kinase known to have noncatalytic signaling function important in healthy and disease cell signaling.

UM-164: A Potent c-Src/p38 Kinase Inhibitor with In Vivo Activity against Triple-Negative Breast Cancer.

Purpose: c-Src has been shown to play a pivotal role in breast cancer progression, metastasis, and angiogenesis. In the clinic, however, the limited efficacy and high toxicity of existing c-Src inhibitors have tempered the enthusiasm for targeting c-Src. We developed a novel c-Src inhibitor (UM-164) that specifically binds the DFG-out inactive conformation of its target kinases.

Conformation-Selective Analogues of Dasatinib Reveal Insight into Kinase Inhibitor Binding and Selectivity.

In the kinase field, there are many widely held tenets about conformation-selective inhibitors that have yet to be validated using controlled experiments. We have designed, synthesized, and characterized a series of kinase inhibitor analogues of dasatinib, an FDA-approved kinase inhibitor that binds the active conformation. This inhibitor series includes two Type II inhibitors that bind the DFG-out inactive conformation and two inhibitors that bind the αC-helix-out inactive conformation.

Discovery of Bivalent Kinase Inhibitors via Enzyme-Templated Fragment Elaboration.

We have employed novel fragment-based screening methodology to discover bivalent kinase inhibitors with improved selectivity. Starting from a low molecular weight promiscuous kinase inhibitor, we appended a thiol for subsequent reaction with a library of acrylamide electrophiles. Enzyme-templated screening was performed to identify acrylamides that assemble into bivalent inhibitors of c-Src kinase.

Substrate activity screening with kinases: discovery of small-molecule substrate-competitive c-Src inhibitors.

Substrate-competitive kinase inhibitors represent a promising class of kinase inhibitors, however, there is no methodology to selectively identify this type of inhibitor. Substrate activity screening was applied to tyrosine kinases. By using this methodology, the first small-molecule substrates for any protein kinase were discovered, as well as the first substrate-competitive inhibitors of c-Src with activity in both biochemical and cellular assays.

Irreversible inhibitors of c-Src kinase that target a nonconserved cysteine.

We have developed the first irreversible inhibitors of wild-type c-Src kinase. We demonstrate that our irreversible inhibitors display improved potency and selectivity relative to that of their reversible counterparts. Our strategy involves modifying a promiscuous kinase inhibitor with an electrophile to generate covalent inhibitors of c-Src.