Mitochondrial superoxide anion overproduction in Tet-mev-1 transgenic mice accelerates age-dependent corneal cell dysfunctions.
OBJECTIVE
The Tet-mev-1 mouse expressing a mitochondrial complex-II mutated SDHC(V69E) gene controlled by a tetracycline (Tet)-On/Off system can overproduce O(2)(·-) and is a versatile whole-animal model for studying mitochondrial oxidative stress. Here we report a series of age-dependent variations in corneal epithelium, endothelium, and parenchymal cells of the Tet-mev-1 mice relative to wild-type C57BL/6j mice.


METHODS
Measurements of (1) mitochondrial electron transport enzyme activities; (2) O(2)(·-) production; (3) carbonylated protein, and 8-hydroxydeoxyguanosine (8-OHdG) levels as markers of oxidative stress; (4) pathologic analyses under optical and electron microscopy; (5) hematoxylin-eosin or toluidine-blue staining; and (6) immunohistochemistry with an anti-β-catenin antibody were performed in the eye, especially the cornea.


RESULTS
Complex II-III activity was decreased by electron leakage between complex II and CoQ. This resulted in increased age-dependent intracellular oxidative stress in the eye of Tet-mev-1 mice. Corneal epithelialization was delayed in Tet-mev-1 mice after 20% ethanol treatment, as the number of cells and mitotic cells decreased in the corneal epithelium of Tet-mev-1 mice compared with that of wild type. The age-dependent decrease in cell number accelerated in the corneal endothelium cells. Moreover, it was suggested that the corneal thickness was decreased by thinning of parenchymal cells with age in Tet-mev-1 mice.


CONCLUSIONS
These results suggest that mitochondrial oxidative stress with electron transport chain dysfunction can influence pathogenesis and progression of age-related corneal diseases, as well as generalized corneal aging acceleration.
Department of Ophthalmology, Tokai University School of Medicine, Isehara, Kanagawa, Japan.
Hiromi
H
Onouchi
Takamasa
T
Ishii
Masaki
M
Miyazawa
Yuichi
Y
Uchino
Kayo
K
Yasuda
Phil S
PS
Hartman
Kenji
K
Kawai
Kazuo
K
Tsubota
Naoaki
N
Ishii
D000080242:8-Hydroxy-2'-Deoxyguanosine; D000375:Aging / Q000502:physiology*; D000818:Animals; D015153:Blotting, Western; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D002374:Catalase / Q000378:metabolism; D002452:Cell Count; D003316:Corneal Diseases / Q000235:genetics / Q000378:metabolism*; D045303:Cytochromes b; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000378:metabolism; D042963:Electron Transport Complex II / Q000378:metabolism; D004728:Endothelium, Corneal / Q000473:pathology; D019084:Fluorescent Antibody Technique, Indirect; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism*; D018384:Oxidative Stress; D050050:Protein Carbonylation; D013385:Succinate Dehydrogenase / Q000235:genetics; D013481:Superoxides / Q000378:metabolism*; D013752:Tetracycline
D029742:Caenorhabditis elegans Proteins; C472666:MEV-1 protein, C elegans; D013481:Superoxides; D000080242:8-Hydroxy-2'-Deoxyguanosine; D045303:Cytochromes b; D002374:Catalase; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase; D013752:Tetracycline; D003849:Deoxyguanosine