Authors:

Angel Yin

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About Paper:

Janus kinase 2 (JAK2) hyperactivation drives sustained STAT1 phosphorylation and pathogenic immune signaling in inflammatory skin diseases such as alopecia areata. Although FDA-approved JAK inhibitors are clinically available, their ATP-competitive mechanisms often result in limited specificity and adverse effects, motivating the development of alternative strategies for more selective pathway inhibition. This project tested that protein-like polymers (PLPs) designed as proteomimetics of the endogenous JAK/STAT regulator SOCS1 can selectively inhibit JAK2 through substrate-site binding while improving intracellular stability and cellular uptake. SOCS1-derived peptides were synthesized and displayed multivalently on peptide brush polymers with synthetic backbones to generate JAK2-targeting PLPs of defined lengths. Monomer purification and polymerization were validated using mass spectrometry, analytical and preparative high-performance liquid chromatography, and proton nuclear magnetic resonance spectroscopy. Additional analysis was performed in human keratinocyte models using cell viability assays and western blot analysis of cytokine-induced STAT1 phosphorylation. Competitive binding assays further demonstrated specific interactions between PLPs and the JAK2 enzyme, while peptide-only and scrambled polymer controls showed no measurable binding. The PLPs entered cells autonomously, exhibited extended intracellular stability, and produced on-target inhibition of STAT1 phosphorylation without ATP competition. Cell viability assays showed that the 10mer PLP was non-cytotoxic up to 10 sM, whereas the 20mer remained viable up to approximately 7 uM, with the 10mer demonstrating greater efficacy in suppressing STAT1 phosphorylation. Collectively, these results indicate that multivalent PLP design enables selective JAK2 inhibition with improved safety and functional performance relative to conventional small-molecule inhibitors. This work supports protein-like polymers as a therapeutic for selective intracellular kinase inhibition and advances their potential application for inflammatory skin disease.

Source:

Northwestern University

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Co-authors:

Angel Yin