Baljit Kaur, Ashraf Abdo, Sungwoo Cho, Moustafa Gabr

bioRxiv - Pharmacology and Toxicology

DOI: 10.64898/2026.10.12.758423

Abstract

NOS1AP is an adaptor for neuronal nitric oxide synthase that engages several partner proteins and is implicated in Alzheimer's disease. Efforts to drug NOS1AP have sought to disrupt these; we instead report pharmacological stabilization of one interaction. Affinity selection of a 1.4-billion-member DNA-encoded library identified a benzimidazole-5-carboxamide chemotype, optimized by fragment-directed SAR to NOSTRA with submicromolar NOS1AP binding affinity. Of six interactions, NOSTRA enhanced only SCRIB binding, with a cooperativity factor of 30, predominantly through a 14-fold slowing of dissociation; native mass spectrometry resolved a NOS1AP:NOSTRA:SCRIB ternary complex. In healthy human iPSC-derived cortical neurons, NOSTRA engaged the endogenous complex and activated Rac1 without cytotoxicity; in Alzheimer's patient-derived neurons, it lowered the Aβ42/Aβ40 ratio and p-tau217, reduced neurofilament light and improved network activity. With an in vitro ADME profile consistent with CNS exposure, NOSTRA is the first molecular glue for a NOS1AP complex, establishing interaction stabilization as a viable NOS1AP pharmacology.