Abstract
Purpose :
Drebrin (Dbn1), an actin-binding and cell junctional protein, plays a crucial role in various actin-dependent cellular processes in different cell types. Although actin cytoskeletal organization and cell-cell junctions are recognized to have a vital role in lens development, architecture and function, the role of Dbn1 in these processes is not known. In this study, we investigated the role of Dbn1 in lens development and function.
Methods :
Expression and distribution profiles of Dbn1 in embryonic and adult mouse (C57BL/6J) lenses were determined by RT-PCR, immunoblot, and immunofluorescence analyses. A Dbn1 lens conditional knockout (cKO) mouse was generated using Dbn1 floxed and Le-Cre transgenic mice. Embryonic, neonatal and postnatal lenses derived from Dbn1 cKO mice (F5-7 generation with C57BL/6J background) were characterized using histological, immunofluorescence, and confocal imaging approaches using Dbn1 floxed and Le-Cre transgenic mice as controls for comparison.
Results :
The Drebrin E isoform of Dbn 1 is readily detectable in mouse lenses, exhibiting higher expression in neonatal specimens relative to adult lenses. Immunofluorescence analysis reveals much higher Dbn1 staining in fiber cells compared to the lens epithelium. Dbn1 co-distributes with actin and ZO-1 in the lens. Absence of Dbn1 was confirmed in Dbn1 cKO mice, which exhibited microphthalmic eyes with cataracts at the P21 stage. Dbn1 cKO lenses also exhibit a progressive phenotype starting from E12.5, including reduced size and altered shape with swollen and disorganized lens fibers compared to control mice. P1 Dbn1 cKO lenses display extensive fiber cell disorganization with thinning of the epithelium with markedly reduced numbers of nuclei, disruptions in membrane organization of the spectrin-actin cytoskeleton and ZO-1, but no change in AQP0 relative to control lenses. Additionally, Dbn1 cKO mice also exhibit dysgenesis of iridocorneal angle tissues with the adhesion of iris to the cornea and lens. Heterozygous Dbn1 cKO mice also exhibit a moderate, though less severe lens phenotype compared to the homozygous Dbn1 cKO mouse.
Conclusions :
Taken together, this ongoing study reveals an essential role for Dbn1 in lens development, growth, epithelial phenotype, survival, fiber cell polarity, migration, and adhesive interactions.
This is a 2020 ARVO Annual Meeting abstract.