Absence of Vsx1 expression in the normal and damaged mouse cornea

PURPOSE To examine the expression of visual system homeobox 1 (Vsx1) in the mouse cornea and its potential role in the corneal wound response pathway. METHODS Expression of Vsx1 was examined by quantitative reverse-transcription PCR (qRT-PCR) in corneal tissue from developing and adult mice and from mice that had undergone alkali-burn corneal wounding. Immunolabeling and Vsx1 knock-in reporter gene expression in wild type and Vsx1 null-mice were used to confirm the qRT-PCR data. RESULTS Using qRT-PCR, Vsx1 expression was not detected in either the postnatal or adult mouse cornea or in corneas following wounding. This qRT-PCR data was supported by the absence of specific Vsx1 immunolabeling and Vsx1 knock-in reporter expression in untreated and wounded corneas. CONCLUSIONS In mice, Vsx1 mRNA, protein or reporter gene expression is not detected in the normal or damaged cornea. These results make it uncertain what role VSX1/Vsx1 plays in corneal biology. Future experiments examining the pathogenicity of VSX1 mutations associated with corneal dystrophy are required to rule out species differences and possible non-cell autonomous roles for VSX1 in the cornea.