CPNE1: A novel therapeutic target for myopia progression – from genetic GWAS discovery to functional validation in vitro and vivo

Myopia, a complex condition influenced by genetic and environmental factors, is an increasing global health concern, and its underlying mechanisms remain unclear. Genome-wide association studies (GWAS) meta combined with summary-data-based Mendelian randomization (SMR) is a robust tool to identify novel regulatory genes associated with myopia. We performed a fixed-effect meta-analysis of two large-scale GWAS comprising 41,468 cases and 817,202 controls to identify genome-wide significant loci associated with myopia. Potential functional myopia-associated genes were prioritized using SMR. Bayesian colocalization analysis, Mendelian randomization (MR) analysis, and validation in an independent cohort were used to verify the causal roles of the candidate genetic loci. DEGseq2 differential expression and machine learning-based Least Absolute Shrinkage and Selection Operator (LASSO) feature selection were used to investigate scleral transcriptomic analyses and strengthen the protective role of CPNE1 in myopia. Single-cell RNA sequencing (scRNA-seq) and immunofluorescence (IF) were used to localize Copine1 (CPNE1) expression within ocular tissues. CPNE1 was overexpressed by adeno-associated virus (AAV) at the scleral level in a lens-induced myopia (LIM) model, and its potential inhibitory role in eye axial length elongation in scleral fibroblasts was also explored. CPNE1 was overexpressed in vitro in scleral fibroblasts using a lentiviral vector, and downstream molecular changes associated with scleral remodeling were subsequently analyzed. The GWAS meta-analysis identified 35 genome-wide significant loci associated with myopia. Integrative SMR and colocalization analyses consistently prioritized CPNE1 (SMR: false discovery rate < 0.05; colocalization: PP_H4 = 0.988). MR analysis supported a causal CPNE1 protective role in myopia (Wald [odds ratio (OR)] = 0.97; inverse-variance weighted [IVW] [OR] = 0.98). Transcriptomic profiling demonstrated significant CPNE1 downregulation in myopic sclera (log₂FoldChange = − 7), and LASSO regression identified CPNE1 as a predicative feature gene. ScRNA-seq and imunnohistofluorescence localized CPNE1 expression predominantly to scleral fibroblasts. Additionally, in the LIM model, CPNE1 expression was significantly decreased, while AAV-mediated overexpression of CPNE1 attenuated axial elongation and refractive error progression. Mechanistically, CPNE1 overexpression correlated with upregulated α-smooth muscle actin (α-SMA) levels, suggesting its potential role in scleral remodeling. Overexpression of CPNE1 in scleral fibroblasts significantly upregulated the expression of TGF-β1, COL1A1, and α-SMA, suggesting a potential role of CPNE1 in myopia pathogenesis through cell cycle-associated regulation and the promotion of scleral fibrotic remodeling. CPNE1 may represent a novel potential therapeutic target for myopia and provide insights into the molecular mechanisms underlying its pathogenesis.