LPA1-Induced EMT of Retinal Pigment Epithelial Cells Promotes Subretinal Fibrosis via USP1-Mediated Deubiquitination and Stabilization of ZEB1.

PURPOSE: Subretinal fibrosis (SRF) is a vision-threatening complication of neovascular age-related macular degeneration (nAMD), yet effective antifibrotic strategies remain limited. This study investigated the role of lysophosphatidic acid receptor 1 (LPA1), a fibrosis-associated G protein-coupled receptor, in SRF progression and evaluated its therapeutic potential. METHODS: A two-stage laser injury model was used to induce SRF in C57BL/6J mice. LPA1 expression and its regulation of ubiquitin-specific peptidase 1 (USP1) and zinc finger E-box binding homeobox 1 (ZEB1) were assessed by western blotting and immunofluorescence. Retinal pigment epithelial (RPE) cell epithelial-mesenchymal transition (EMT) was evaluated by migration assays and fibrotic marker analysis. ZEB1 and USP1 loss-of-function experiments were performed to define their roles. Molecular docking and co-immunoprecipitation were used to examine USP1-mediated ZEB1 deubiquitination. The antifibrotic effects and the safety of LPA1 inhibition by BMS-986278 were assessed in vivo. RESULTS: LPA1 was upregulated in laser-induced SRF and was associated with increased fibrotic marker expression. LPA1 overexpression promoted RPE EMT and migration through the USP1/ZEB1 axis. Mechanistically, LPA1 increased USP1 expression, which stabilized ZEB1 and promoted its nuclear translocation by reducing ZEB1 ubiquitination. USP1 inhibition attenuated LPA1-induced EMT and fibrosis, similar to ZEB1 silencing. In vivo, BMS-986278 suppressed EMT and reduced SRF severity, with a stronger inhibitory effect on fibrotic lesions than on neovascular lesions. CONCLUSIONS: LPA1 promotes SRF by driving RPE EMT through USP1-mediated deubiquitination and stabilization of ZEB1. Targeting the LPA1/USP1/ZEB1 axis may provide a promising therapeutic strategy for nAMD-associated SRF.