Identification of Amino Acids That Regulate Angiogenesis and Alter Pathogenesis of a Mouse Model of Choroidal...

Background: Metabolic stress from amino acid (AA) insufficiency is increasingly linked to pathological angiogenesis, but specific essential AA (EAA) roles remain undefined. Neovascular age-related macular degeneration (AMD), a major cause of blindness driven by aberrant ocular neovascularization, has limited efficacy with current VEGFA-targeting therapies. We sought to identify specific EAAs that regulate pathological angiogenesis and dissect their mechanisms to propose new therapeutic strategies. Methods: Human retinal microvascular endothelial cells (HRMVECs) were used to identify angiogenesis-regulating amino acids through systematic EAA screening. The molecular mechanism was investigated using shRNA-mediated knockdown of key stress response regulators (HRI, PKR, PERK, GCN2) and ATF4. Angiogenesis was assessed via tubule formation and migration assays. Therapeutic potential was examined in a laser-induced choroidal neovascularization (CNV) mouse model, evaluated by fluorescein angiography and histomorphometry. Results: Deprivation of methionine, lysine, and threonine potently induced capillary-like tube formation (p < 0.01). Mechanistically, restriction of these three EAAs activated HRI and GCN2 kinases, converging on eIF2α phosphorylation to induce ATF4 and its target VEGFA. Dual, but not single, knockdown of HRI and GCN2 abolished eIF2α-ATF4 signaling and angiogenic responses. Restricting these EAAs exacerbated CNV area in mice. Conclusions: Our findings reveal a coordinated HRI/GCN2-ATF4-VEGFA axis linking EAA scarcity to vascular remodeling, establishing proof-of-concept for targeting this pathway in CNV. This work highlights the therapeutic potential of modulating specific AA availability or targeting the HRI/GCN2-ATF4 axis to treat CNV.