Identification of small-molecule inhibitors of the JIP–JNK interaction

Abstract

JNK1 (c-Jun N-terminal kinase 1) plays a crucial role in the regulation of obesity-induced insulin resistance and is implicated in the pathology of Type 2 diabetes. Its partner, JIP1 (JNK-interacting protein 1), serves a scaffolding function that facilitates JNK1 activation by MKK4 [MAPK (mitogen-activated protein kinase) kinase 4] and MKK7 (MAPK kinase 7). For example, reduced insulin resistance and JNK activation are observed in JIP1-deficient mice. On the basis of the in vivo efficacy of a cell-permeable JIP peptide, the JIP-JNK interaction appears to be a potential target for JNK inhibition. The goal of the present study was to identify small-molecule inhibitors that disrupt the JIP-JNK interaction to provide an alternative approach for JNK inhibition to ATP-competitive inhibitors. High-throughput screening was performed by utilizing a fluorescence polarization assay that measured the binding of JNK1 to the JIP peptide. Multiple chemical series were identified, revealing two categories of JIP/JNK inhibitors: 'dual inhibitors' that are ATP competitive and probably inhibit JIP-JNK binding allosterically, and 'JIP-site binders' that block binding through interaction with the JIP site. A series of polychloropyrimidines from the second category was characterized by biochemical methods and explored through medicinal-chemistry efforts. As predicted, these inhibitors also inhibited full-length JIP-JNK binding and were selective against a panel of 34 representative kinases, including ones in the MAPK family. Overall, this work demonstrates that small molecules can inhibit protein-protein interactions in vitro in the MAPK family effectively and provides strategies for similar approaches within other target families.

Inhibition of JNK Mitochondrial Localization and Signaling Is Protective against Ischemia/Reperfusion Injury in Rats

“…Given that the JNK-Sab interaction has significant affinity contributions from the 11-amino acid KIM domain, as evidenced by the 218 nM IC 50 for Tat-Sab KIM1 versus Sab protein (14), the notion of making Sab-competitive small molecule inhibitors or bidentate small molecule JNK inhibitors that span the ATP pocket as well as the substrate binding domain is feasible. Indeed, a few such compounds have been reported that are either competitive versus JIP (27) or that have some bidentate character (28 -31). If these compounds can be improved in terms of potency, selectivity, and drug-like prop-erties, our results now show that selective inhibition of JNK mitochondrial signaling might be achieved with therapeutic benefit.…”

The Fluorescent Two-Hybrid Assay to Screen for Protein–Protein Interaction Inhibitors in Live Cells: Targeting the Interaction of p53 with Mdm2 and Mdm4

“…12 In summary, no ideal system to monitor reversible PPIs in mammalian cells is available yet. Typically, several methods have to be combined to reliably screen for inhibitors of PPIs and confirm the mechanism of action in independent systems (e.g., Chen et al 13 and Zhai et al 14 ).…”

Computational Insights for the Discovery of Non-ATP Competitive Inhibitors of MAP Kinases

“…Unlike 12, however, it inhibits a number of protein kinases, consistent with the reduced selectivity expected of an inhibitor that targets the ATP binding site [96].…”

“…In 2009, Chen et al used a fluorescence polarization assay to screen for compounds that disrupt the JNK-JIP interaction [96]. Compound 12 was found to inhibit the JNK1, JNK2 and JNK3 kinase activity with IC 50 s of 6, 8 and 10 μM respectively.…”