FOXJ1 contributes to transcriptional reprogramming to selectively enhance membrane-associated mucin expression in human corneal epithelial cells

A BSTRACT Objectives: To define the mechanism by which a special medium enhances mucin production in human corneal epithelial cells (HCECs) for potential application in dry eye disease (DED) treatment. Materials and Methods: HCECs were cultured in keratinocyte serum-free medium or a special medium. Mucin and epithelial marker expression was assessed by flow cytometry. Transcriptomic changes were analyzed by ribonucleic acid (RNA) sequencing, Gene Ontology, and Gene Set Enrichment Analysis, and the function of target gene FOXJ1 was examined using shRNA-mediated knockdown and overexpression approaches. Results: The special medium upregulated MUC1, MUC4, and MUC16 without altering epithelial morphology or keratin 3 and keratin 12 expression, suggesting selective enhancement of membrane-associated mucin expression without disruption of corneal epithelial identity. Transcriptomic profiling revealed coordinated activation of mucin biosynthesis pathways alongside mesenchymal-to-epithelial transition-associated programs and identified FOXJ1 as a candidate gene associated with the effects of the special medium. FOXJ1 knockdown induced epithelial-to-mesenchymal transition-like changes and reduced mucin expression, whereas FOXJ1 overexpression selectively enhanced membrane-associated mucins without phenotypic conversion. Conclusion: These findings suggest that FOXJ1 is associated with epithelial homeostasis and membrane mucin expression and highlight the potential of reinforcing epithelial identity as a therapeutic strategy for restoring mucin biogenesis in DED.