OSM-11 modulates salinity-stress tolerance in Caenorhabditis elegans

Most terrestrial animals exhibit narrow salinity tolerance compared to their marine counterparts. Previous studies identified osm-11 (which encodes a Notch co-ligand) mutations as a driver of hyper-saline tolerance in Caenorhabditis elegans, but mechanistic insights remained unclear. This study employs RNA sequencing and CRISPR/Cas-9 genome editing to demonstrate that osm-11 mutations enhance salinity stress resistance through upregulation of fatty acid metabolism (acdh-12, acs-17) and cytochrome P450 pathways (ugt-15), while suppressing calcium signaling. Furthermore, we demonstrated that acdh-12 mutation impairs salinity-stress tolerance by activating ferroptosis and mitophagy, accompanied by down-regulated oxidative phosphorylation and up-regulated autophagic pathways. Morphological observations show that mitochondrial fragmentation contributes to wild-type nematode mortality under high salinity, while enlarged lipid droplets in wild-types correlate with reduced β-oxidation gene expression (dhs-28, daf-22), whose knockout disrupts tolerance in mutants. These findings unravel the multi-pathway regulatory network of osm-11-mediated salinity tolerance, providing mechanistic insights for developing protective strategies against environmental salinity stressors impacting animal survival.