Lisinopril activates BI1 to reprogram lipid metabolism and restore autophagy in ALS

Amyotrophic lateral sclerosis (ALS) involves disrupted lipid metabolism. Bax inhibitor 1 (BI1), an endoplasmic reticulum protein downregulated in ALS neuroprotective, represents a therapeutic target, but its metabolic regulatory mechanisms are incompletely understood. Using transcriptomics in skeletal muscle of ALS mice pre- and post-BI1 treatment, we identified BI1-regulated pathways. Structure-based virtual screening of FDA-approved compounds nominated lisinopril as a BI1 activator. Lisinopril upregulated BI1 protein expression, stabilizing mitochondrial membrane potential and protecting against SOD1^G93A-induced apoptosis in NSC34 cells. Concurrently, it regulated TGF-β1/mTOR-dependent autophagy, maintained NMJ integrity, and reshaped triglyceride/sphingolipid/glycerophospholipid metabolism to attenuate spinal cord pathology in ALS mice, promoting energy metabolism shift toward glucose oxidation. Additionally, lisinopril inhibited the TGF-β1/Smad2/3 pathway to alleviate muscle fibrosis, downregulate Acp5/FN expression, and reduce type I collagen deposition. In conclusion, this study provides evidence that pharmacological activation of BI1 by lisinopril suppresses TGF-β1, modulates lipid metabolism, and ameliorates ALS pathology, demonstrating promising therapeutic repurposing potential.