Structurally normal corneas in aldehyde dehydrogenase 3a1-deficient mice.

We have constructed an ALDH3a1 null mouse to investigate the role of this enzyme that comprises nearly one-half of the total water-soluble protein in the mouse corneal epithelium. ALDH3a1-deficient mice are viable and fertile, have a corneal epithelium with a water-soluble protein content approximately half that of wild-type mice, and contain no ALDH3a1 as determined by zymograms and immunoblots. Despite the loss of protein content and ALDH3a1 activity, the ALDH3a1(-/-) mouse corneas appear indistinguishable from wild-type corneas when examined by histological analysis and electron microscopy and are transparent as determined by light and slit lamp microscopy. There is no evidence for a compensating protein or enzyme. Even though the function of ALDH3a1 in the mouse cornea remains unknown, our data indicate that its enzymatic activity is unnecessary for corneal clarity and maintenance, at least under laboratory conditions.