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Discovery of a Cell-Permeable Gi-Signaling Inhibitor

Naimi, A.; Berger, T.; Dahlhaus, P.; Rossol, M.; Muehle, J.; Steinchen, W.; Bange, G.; Linne, U.; Stincone, P.; Deupi, X.; Schertler, G. F. X.; Juergenliemke, L.; Kostenis, E.; Kockskaemper, J.; Hilger, D.; Petras, D.; Reher, R.

2026-08-04 biochemistry
10.64898/2026.08.02.742274 bioRxiv
Show abstract

Heterotrimeric G proteins regulate diverse physiological processes, yet selective small molecule modulators for the Gi subfamily remain scarce. Here, we employed native metabolomics to screen a fungal culture collection for G protein binders, which led to the discovery of N-hydroxyapiosporamide (NHAP), a fungal specialized metabolite that functionally inhibits Gi-signaling. NHAP selectively binds Gi1 and diminishes Gi1-mediated GTP turnover in biochemical assays. In primary ventricular cardiomyocytes, NHAP largely reversed acetylcholine-induced negative inotropy, demonstrating functional Gi-signaling blockade in a physiological context without acute cytotoxicity. This work establishes NHAP as a first-in-class Gi-selective inhibitor, providing a cell-permeable chemical scaffold for the optimization of next-generation agents to control Gi-signaling in cell-based systems and, ultimately, to target Gi1-driven pathologies.

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