MAP3K1 integrates RhoA/ROCK signaling to regulate epithelial morphogenesis

Biological processes rely on the interplay between genetic and environmental cues, yet the mechanisms underlying gene-gene (G×G) and gene-environment (G×E) interactions remain poorly understood. Using mouse embryonic eyelid closure as an experimentally tractable model, we extend the established S1PR-MAP3K1-JNK signaling axis by identifying a RhoA-ROCK branch as a functionally integrated component of the MAP3K1 network. These pathways converge on paxillin phosphorylation and c-Jun activation, coupling cytoskeletal remodeling with AP-1-dependent transcriptional responses. TurboID-based proximity proteomics identifies Gβ2 and RhoGEF1/5 as candidate intermediates linking MAP3K1 to S1PR and RhoA. Genetic analyses reveal that Rhoa or Rock1 loss alone is harmless, whereas their combined deficiency or single-gene loss in the context of Map3k1 heterozygosity, S1pr deletion, or dioxin exposure disrupts eyelid closure. These findings define RhoA-ROCK as an integral module within a broader MAP3K1 regulatory network that integrates genetic and environmental inputs to ensure robust morphogenesis.