A New Mouse Model of Age-Related Ocular Disease ( Tet-mev-1 Transgenic Mice ) : Oxidative Stress-Induced Ocular Change

Abstract

Purpose: : Much attention has focused on the role of oxidative stress in ocular disease such as dray eye as corneal disease or age-related macular degeneration as retinal disease. Most oxidative stress in cells originates in superoxide anion (O₂^-) generated from electron transport system in mitochondria. Recently, we have constructed a conditional transgenic mouse (Tet-mev-1 mouse) with a point mutation (V69E) in cytochrome b large subunit (SDHC) of complex II of electron transport system which overproduces O₂^- from mitochondria and the amount of the O₂^- overproduction can be arbitrarily controlled by Tetracycline. Therefore, the Tet-mev-1 mouse will be a suitable model to clarify the molecular mechanism of ocular diseases related with O₂^- from mitochondria.

Methods: : Biochemical analysis: O₂^- measurement, complex II activity and oxidized protein.Histopathological analysis: Hematoxylin-eosin staining, Toruidin-blue staining, and nuclear staining.Immunohistochemical analysis: 8-OHdG, β-cateninApoptosis: TUNEL staining was performed.These studies were conducted in compliance with the ARVO.

Results: : O₂^- production and oxidized protein increased and complex II activity decreased in the three-month and twelve-month old Tet-mev-1 mice compared to the same aged wild type mice. Mitotic cell and nuclear cell in the corneal epithelium decreased compared to the same aged wild type mice, and the corneal epithelialization after a 20% ethanol treatment also delayed. 8- OHdG as a maker of oxidized DNA increased in corneal epithelium of the six-month old Tet-mev-1 mouse although there was no difference between three-month old Tet-mev-1 and wild type mice.In addition, the number of cornea endothelial cells also decreased. This was equivalent to that of the twenty four-month old wild type, suggested the decrease of intercellular adhesion ability of cornea endothelial cells at the early stage of Tet-mev-1 mouse.

Conclusions: : Further analyses to know whether these phenomena are related with induction of apoptosis and cell cycle arrest are in progress. Our results suggest that O₂^- from mitochondria would influence pathogenesis and progression of the age-related ocular diseases.

Keywords: oxidation/oxidative or free radical damage • cornea: basic science • aging