| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1 From the Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor; the 2 Eye Research Institute and 3 Department of Biological Sciences, Oakland University, Rochester, Michigan; the 4 Division of Biology, Kansas State University, Manhattan; 5 Institute of Chemical Toxicology, Wayne State University, Detroit, Michigan; and the 6 Departments of Anatomy II and 7 Ophthalmology and Eye Hospital, University of Erlangen-Nurenberg, Germany.
PURPOSE. Previous in vitro studies with transgenic and gene-knockout mice have shown that lenses with elevated levels of glutathione peroxidase (GPX)-1 activity are able to resist the cytotoxic effect of H2O2, compared with normal lenses and lenses from GPX-1–deficient animals. The purpose of this study was to investigate the functional role of this enzyme in antioxidant mechanisms of lens in vivo by comparing lens changes of gene-knockout mice with age-matched control animals.
METHODS. In vivo lens changes were monitored by slit lamp biomicroscopy, and enucleated lenses were examined under a stereomicroscope in gene-knockout animals and age-matched control animals ranging in age from 3 weeks to 18 months. Transmission (TEM) and confocal microscopy were performed on different regions of lenses after the mice were killed at various times.
RESULTS. Slit lamp images showed an increase in nuclear light scattering (NLS) in gene-knockout mice compared with control animals. TEM revealed changes in the nucleus as early as 3 weeks of age by the appearance of waviness of fiber membranes. With increasing age, there was greater distortion of fiber membranes and distension of interfiber space at the apex of fiber cells compared with control mice. The changes in nuclear fiber membranes were even more dramatic, as observed by confocal microscopy, which was performed on thicker sections. In contrast to the changes in the lens nucleus, the morphology of the epithelium and superficial cortex remained unchanged in knockout animals during the same experimental period, consistent with slit lamp observations. Stereomicroscopy of ex vivo lenses demonstrated a significant increase in opacification in gene-knockout mice relative to control animals of the same age. This effect became evident in mice aged 5 to 9.9 months and persisted thereafter in older animals, resulting in mature cataracts after 15 months.
CONCLUSIONS. The results demonstrate the critical role of GPX-1 in antioxidant defense mechanisms of the lens nucleus. The increased NLS appears to be associated with damage to fiber membranes in the nucleus, which is particularly susceptible to oxidative challenge because of the deficiency of GPX-1. It is suggested that the lens membrane changes in the knockout animals may be due to the formation of lipid peroxides, which serve as substrates for GPX-1. Cataract development in gene-knockout mice appeared to progress from focal opacities, apparent at an earlier age, to lamellar cataracts between 6 and 10 months, and finally to complete opacification in animals older than 15 months. This is the first reported phenotype in GPX-1–knockout mice.
This article has been cited by other articles:
|
|
 |
|
  E. Kasahara, L.-R. Lin, Y.-S. Ho, and V. N. Reddy SOD2 Protects against Oxidation-Induced Apoptosis in Mouse Retinal Pigment Epithelium: Implications for Age-Related Macular Degeneration Invest. Ophthalmol. Vis. Sci., September 1, 2005; 46(9): 3426 - 3434. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. MA, D. LI, F. SUN, N. J. KLEIMAN, and A. SPECTOR The effect of stress withdrawal on gene expression and certain biochemical and cell biological properties of peroxide-conditioned cell lines FASEB J, March 1, 2004; 18(3): 480 - 488. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Alizadeh, J. Clark, T. Seeberger, J. Hess, T. Blankenship, and P. G. FitzGerald Targeted Deletion of the Lens Fiber Cell-Specific Intermediate Filament Protein Filensin Invest. Ophthalmol. Vis. Sci., December 1, 2003; 44(12): 5252 - 5258. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y.-S. Ho Transgenic and Knockout Models for Studying the Role of Lung Antioxidant Enzymes in Defense against Hyperoxia Am. J. Respir. Crit. Care Med., December 15, 2002; 166(12): S51 - 56. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. H. Frederikse and X.-O. Ren Lens Defects and Age-Related Fiber Cell Degeneration in a Mouse Model of Increased A{beta}PP Gene Dosage in Down Syndrome Am. J. Pathol., December 1, 2002; 161(6): 1985 - 1990. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
