Effects of the Targeted Deletion of the Lens Specific Intermediate Filament Protein CP49

Abstract

Abstract: : Purpose: To describe the effects of the targeted deletion of the lens specific intermediate filament protein, CP49, upon the lens morphology, optical quality and cytoskeletal arrangement. Methods: The targeting strategy was developed after first identifying the promoter and surrounding sequences for the CP49 gene. The minimal promoter was identified by deletion analysis by transfection of promoter constructs into E15 chick lens explants and monitoring reported gene ativity. Targeting vector was constructed to remove the minimal promoter and first exon of the mouse CP49 gene. Chimeric mice were produced from successfully targeted ES cell clones and germline transmission checked by Southern blotting. Heterozygous intercross matings were set up to generate the CP49 knockout for phenotypic examination by slit lamp analysis followed by biochemical and morphological analyses of the lenses. Wild type litter mates were used as controls. Results: As expected, the loss of CP49 altered the lens fibre cell cytoskeleton morphology. It also changed the stability of its assembly partner, filensin. Despite these major changes in the lens specific cytoskeleton, only subtle changes in light scatter for the CP49 knockout lenses were observed. In contrast, helium neon laser scan analysis revealed a significant deterioration in lens function. Conclusions: The optical quality of the lens depends upon a functional beaded filament cytoskeleton.

Keywords: cytoskeleton • animal model • optical properties