NEDD8 Promotes the Progression and Inflammation of Keratoconus by Increasing the Expression of YAP1.

Purpose: Keratoconus (KC) is an adolescent-onset vision-impairing corneal disorder with incompletely elucidated pathogenesis. This study aims to elucidate the regulatory role of NEDD8 in the Hippo-YAP signaling pathway and its influence on the corneal pathology, thereby providing a theoretical basis for mechanistic studies and targeted therapy of KC. Methods: Single-cell RNA sequencing (scRNA-seq) analysis of central corneas was performed to identify differentially expressed molecules and signaling pathways in KC. Then the expression changes and correlations of key regulatory molecules were validated at both the transcriptional and protein levels. We subjected HTK cells to mechanical stretch and used gain- or loss-of-function assays to demonstrate the regulatory role of key signaling pathways. In addition, ligand-receptor interaction analysis was performed to decipher aberrant immune-stromal cell crosstalk in KC. Results: NEDD8 was significantly upregulated in KC corneal stromal cells, with decreased MST1/LATS1 expression and increased YAP1 nuclear translocation. In vitro experiments indicated that mechanical stretch may inhibit the Hippo pathway by upregulating NEDD8, thereby reducing YAP1 phosphorylation and enhancing its transcriptional activity. We detected signs of elevated inflammation and dysregulated stromal-immune ligand-receptor pairs in KC samples. Overexpression of NEDD8 and YAP1 significantly increased inflammatory cytokine levels in HTK cells, whereas NEDD8 inhibitor treatment suppressed the mechanical stretch-triggered inflammatory responses. Conclusions: Collectively, our study revealed that NEDD8 may promote KC progression by mediating mechanical signal transduction through regulation of the Hippo-YAP pathway. These findings highlight NEDD8 as a promising therapeutic target for KC and provide novel mechanistic insights into its molecular pathogenesis.