SPARC Promotes Corneal Epithelial Wound Healing Through β-catenin Nuclear Translocation and c-Met Activation.

PURPOSE: To investigate the molecular mechanism through which secreted protein acidic and rich in cysteine (SPARC) facilitates corneal epithelial wound healing via the β-catenin/c-Met signaling pathway.

METHODS: Wild-type C57BL/6 mice, Sparc-/- mice, and human corneal epithelial cells (HCECs) were used. Corneal epithelial repair was assessed by sodium fluorescein staining, hematoxylin and eosin staining, EdU incorporation, and Cell Counting Kit-8 assays. SPARC- and pathway-related changes were evaluated by quantitative RT-PCR, immunofluorescence, Western blotting, and flow cytometry. β-Catenin-c-Met interaction was analyzed by co-immunoprecipitation. Tandem mass tag-based phosphoproteomics compared phosphorylation profiles between control and exogenous SPARC-treated groups.

RESULTS: In vivo and in vitro analyses showed that SPARC promoted corneal epithelial wound healing. SPARC deficiency delayed epithelial closure, reduced epithelial thickness, and impaired epithelial-stromal adhesion, whereas exogenous SPARC partially rescued these defects. In HCECs, SPARC knockdown reduced cell proliferation and migration. Mechanistically, SPARC loss decreased β-catenin expression and nuclear translocation, downregulated c-Myc, and reduced c-Met mRNA expression, total protein abundance, and phosphorylation. Silencing either β-catenin or Met impaired epithelial repair, whereas exogenous SPARC or pathway agonists partially restored these phenotypes. Co-immunoprecipitation further showed that SPARC deficiency weakened the interaction between β-catenin and c-Met.

CONCLUSIONS: SPARC promotes corneal epithelial wound healing by enhancing β-catenin nuclear translocation and c-Met activation, thereby promoting epithelial proliferation and migration. The SPARC-β-catenin-c-Met axis may represent a therapeutic target for corneal epithelial injury.