Optimizing function-selective ERK1/2 inhibitors for reducing AP-1-mediated airway pathology in asthma.

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Project Summary Asthma pathogenesis is characterized by airway inflammation, remodeling and hyperresponsiveness resulting in severe bronchoconstriction. Allergen-induced inflammatory mediators act on immune cells and structural airways cells and activate intracellular signaling. The Activator Protein-1 (AP-1) transcription factor complex is a central regulator that responds to signaling pathways activated by cytokines, growth factors and other inflammatory signals in airway cells to mediate airway remodeling in asthma. Therefore, upregulated AP-1, which contributes to multiple features of asthma pathogenesis, is an attractive anti-asthma therapeutic target. The Extracellular signal‑Regulated protein Kinases (ERK1/2) are key regulators of AP-1 activity in airway smooth muscle (ASM), lung fibroblasts (LF), and other lung cells that contribute to the pathology of asthma. Taking advantage of ERK1/2 structural interactions with specific substrates, we identified a novel compound that binds to a unique ERK1/2 substrate docking site that mediates interactions with AP-1 complex proteins and inhibits ERK1/2- mediated AP-1 activity. Targeting select kinase functions offers advantages in reducing acquired drug resistance and toxicity observed with the current kinase inhibitors that target ATP binding sites and block all enzymatic activity. We demonstrate that function-selective ERK1/2 inhibitors inhibit ASM cell proliferation, AP-1 activity, and mitigate multiple features of allergic asthma in a murine model. Considering that upregulated ERK1/2 activity contributes to the pathogenesis of asthma, we hypothesize that function-selective inhibition of ERK1/2 signaling through the AP-1 will mitigate ASM and LF cell hyperplasia, hypertrophy, extracellular matrix (ECM) hypersecretion, and other features of asthma. The R61 phase will consist of two aims. Aim 1 will use computer-aided drug design and chemical synthesis to generate optimized analogs of a lead function-selective ERK1/2 inhibitor that targets regulation of AP- 1 proteins. Aim 2 will evaluate new compounds in regulating AP-1 mediated hyperplasia, ECM secretion, and inflammatory mediators in primary ASM and LF cells obtained from normal and asthmatic lungs. Aim 3 in the R33 phase will employ an integrated mouse model of asthma to assess the most potent compounds in mitigating multiple features of allergic asthma. In addition, R33 phase will collaborate with an Accelerator Partner, Gen1E, Life Sciences, to perform pre-clinical testing and development of the top 3 compounds focusing on pharmacokinetic evaluation, kinase selectivity, off-target effects, and toxicity. These studies will provide important pre-clinical data to advance a novel therapy that effectively inhibits a major effector target (e.g., AP-1) involved in the pathology of asthma.