Identification of a new JNK inhibitor targeting the JNK-JIP interaction site

Abstract

JNK is a stress-activated protein kinase that modulates pathways implicated in a variety of disease states. JNK-interacting protein-1 (JIP1) is a scaffolding protein that enhances JNK signaling by creating a proximity effect between JNK and upstream kinases. A minimal peptide region derived from JIP1 is able to inhibit JNK activity both in vitro and in cell. We report here a series of small molecules JIP1 mimics that function as substrate competitive inhibitors of JNK. One such compound, BI-78D3, dose-dependently inhibits the phosphorylation of JNK substrates both in vitro and in cell. In animal studies, BI-78D3 not only blocks JNK dependent Con A-induced liver damage but also restores insulin sensitivity in mouse models of type 2 diabetes. Our findings open the way for the development of protein kinase inhibitors targeting substrate specific docking sites, rather than the highly conserved ATP binding sites. In view of its favorable inhibition profile, selectivity, and ability to function in the cellular milieu and in vivo, BI-78D3 represents not only a JNK inhibitor, but also a promising stepping stone toward the development of an innovative class of therapeutics. JNKs are serine threonine protein kinases and members of the MAPK family (1-3). JNKs can be expressed as 10 different isoforms by mRNA alternative splicing of three highly related genes, JNK1, JNK2, and JNK3 (4). Although JNK1 and JNK2 are ubiquitous, JNK3 is principally present in the brain, cardiac muscle, and testis (4, 5). JNK activation by extracellular stimuli, such as stress or cytokines, leads to the phosphorylation of several transcription factors, and cellular substrates implicated in cell survival and proliferation, insulin receptor signaling, and mRNA stabilization (6-9). Because these pathways are related to the pathogenesis of several diseases, including diabetes, cancer, atherosclerosis, stroke, and Alzheimer's and Parkinson's diseases, JNKs represent valuable targets in the development of new therapies (10).JNKs bind to scaffold proteins and substrates containing a D-domain, consensus sequence of which is R/KXXXXLXL (11, 12). JNK-interacting protein-1 (JIP1) is a scaffolding protein that enhances JNK signaling by creating a proximity effect between JNK and upstream kinases (13). The JNK-JIP1 interaction is mediated by a specific, high affinity D-domain on JIP1, the critical features of which were elucidated by Barr and colleagues (14). Overexpression of either the D-domain of JIP1 or the full-length protein potently inhibits JNK signaling in the cell (15). The minimal region of JIP1, consisting of a single D-domain, has been identified as a JNK inhibitor (14, 16). A peptide corresponding to the D-domain of JIP1 (amino acids 153-163; pepJIP1), inhibits JNK activity in vitro toward recombinant c-Jun, Elk, and ATF2 and displays remarkable selectivity with little inhibition of the closely related Erk and p38 MAPKs (17).The mechanism of JNK1 inhibition by pepJIP1 is mainly because of the competition of pepJIP1 with the D-domains of substrat...

Novel compounds reducing IRS-1 serine phosphorylation for treatment of diabetes

“…9 Moreover, they improved functional β-cell mass in transplanted human pancreatic islets both in vitro and in vivo in the early post-transplant period. 10 In addition, several JNK inhibitors have been shown to improve insulin sensitivity and glucose tolerance in db/db diabetic mice [11][12][13] and in mice fed a high-fat diet. 14 Consequently, JNK inhibitors are generally considered as potential antidiabetic agents.…”

Insulin resistance pathogenesis in metabolic obesity

“…В эксперименте это соединение вызывало снижение веса, концентрации глюкозы и триглицеридов в крови и восстанавливало чувствительность к инсулину у мышей с ожирением [70]. Конкурентный ингибитор JNK -BI-78D3, восстанавливал чувствительность к инсулину у мышей с СД 2 типа после однократного приёма [71]. Один из ингибиторов JNK последнего поколения -соединение 19, мощный селективный конкурентный ингибитор, как в отношении белкового субстрата, так и к АТP.…”

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

“…BI-78D3 was identified as a non-ATP inhibitor of JNK that efficiently displaces biotinylated pepJIP1 from GST-JNK1 with an IC 50 of 500 nM. Molecular modeling studies suggested that the benzodioxan moiety of BI-78D3 binds a small pocket in the DRS of JNK [92] characterized by an extensive hydrogen-bonding network to Arg-127 of JNK1. BI-78D3 exhibits dose-dependent inhibition of the phosphorylation of JNK substrates, both in vitro and in cells, with selectivity for JNK over p38 MAPKα, mTOR and PI3-kinase.…”

“…This confirms the hypothesis that the targeting of the DRS of JNK represents a viable approach for the inhibition of JNK signaling in vivo. (8) as the first small molecule to target the JNK-JIP interaction [92]. BI-78D3 was identified as a non-ATP inhibitor of JNK that efficiently displaces biotinylated pepJIP1 from GST-JNK1 with an IC 50 of 500 nM.…”