Abstract
Eye lens obsolescence (Elo) is a heritable, autosomal dominant eye disorder in mice. The Elo mutation lies close to the Len-1 locus on mouse chromosome 1. As it was previously speculated that the Elo locus affects the expression level of γ-crystallin, we first compared the amount of lens γ-crystallin between Elo and normal mice using the 2D-gel electrophoresis. The lens extracts from 10-day-old Elo mice revealed the same profiles and expression levels of α- and β-crystallins as those of +/+ mice. The lower γ-crystallin level could be detected as early as the 14-days stage in the lens of the Elo mouse embryo. The concentration of γ2-crystallin mRNA in Elo mice lens was estimated at 1/13 of that of normal lens, indicating that a small amount of transcript production from γ-crystallin genes may cause the low level of γ-crystallin in Elo lens.
To map precisely the mutation locus of Elo on mouse chromosome 1, linkage analysis was achieved using backcross mating between Elo and 129/SvJ (+/+) . Restriction endonuclease Dra I showed distinct RFLP patterns in both y2- and y4-crystallin genes. The backcross offsprings were analyzed with respect to Elo, Idh-1, Cryg-1, and Cryg-4 loci among 223 mice.
Deficiency in a 94-kDa peptide in the non-crystallin fraction from the Elo mouse lens was shown. An antibody was raised against the 94-kDa peptide isolated from normal mouse lens. The 94-kDa peptide was only observed in the lens, and was unique to mouse lens cortex and nucleus fractions, not being present in epithelial cells. The obtained antibody reacted but weakly with the avian CP97 lens peptide. From these results, we concluded that the 94-kDa antigen corresponds to a lens fiber cellspecific cytoskeletal protein of the mouse. The peptide was deficient in the lenses from Elo mice, but it was contained at the normal level in microphthalmic lenses from CTA mice. The fact indicates that the peptide is not lacking in all microphthalmic lens. It is possible that the suppression of expression of this 94-kDa peptide causes the defective elongation in Elo lens fiber cells.
