[Frontiers in Bioscience E4, 141-155, January 1, 2012]

Oxidative stress defense and repair systems of the ocular lens

Lisa Ann Brennan1, Rebecca Susan McGreal1, Marc Kantorow1

1Biomedical Sciences Department, Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, USA.

TABLE OF CONTENTS

1. Abstract
2. Human eye lens
2.1. Sources of lens ROS
2.2. Defense systems in the lens
3. General ROS scavengers of the eye lens
3.1. Glutathione
3.2. Ascorbate
3.3. Vitamin E
3.4. Carotenoids
4. Antioxidant enzymes of the eye lens
4.1. Superoxide dismutases
4.2. Hydrogen peroxide detoxifiers
4.2.1. Catalase
4.2.2. The Peroxiredoxins
4.2.3. Glutathione peroxidase
5. Free metal detoxifiers of the eye lens
5.1. Metallothioneins
5.2. Ferritin
6. Protein repair systems of the eye lens
6.1. Methionine sulfoxide reductases
6.2. Thioltransferases
7. Reducing systems of the eye lens
7.1. Thioredoxin and thioredoxin reductase
8. Chaperone proteins of the eye lens
8.1. α-crystallin
9. Summary
10. References

1. ABSTRACT

It is well accepted that reactive oxygen species (ROS) play a critical role in many biological processes including disease and longevity. Oxidation of proteins has been linked to many disease states and even the aging process itself. This was first proposed as "The free radical theory of aging" in 1956 by Denham Harman which suggests that free radicals causes cumulative and irreversible damage to macromolecules, loss of cellular function and cell death over time directly impacting health and lifespan. Cellular damage from ROS exposure has been termed oxidative stress, which is an imbalance between cellular ROS production and the ability of the cell to regulate ROS levels and repair damage caused by ROS. This review focuses on the role of oxidative stress in the eye lens as a model for understanding the role of oxidative stress systems in age-related human disease.