Eye--Physiology

The central premise of this dissertation is that mitochondrial antioxidant enzymes
are essential to lens cell viability by preserving lens cell mitochondria and protecting
and/or repairing lens cell proteins, and two mitochondrial-specific antioxidant enzymes,
Peroxiredoxin 3 (PRDX3) and Methionine sulfoxide reductase A (MsrA), are explored.
In this dissertation, we will examine the expression ofPRDX3 in the human lens, its colocalization
to the lens cell mitochondria, its ability to be induced by H20 2-oxidative
stress, and speculate how PRDX3 function/sf could affect the lens. We will also examine
the reduced levels of MsrA by targeted gene silencing and its effect on reactive oxygen
species production and mitochondrial membrane potential in human lens cells to
determine its role in mitochondrial function in the lens. Lastly, we will examine the
ability of MsrA to repair and restore function to a critical mitochondrial protein,
Cytochrome c. The collective evidence strongly indicates that the loss of mitochondrial-specific enzymes, such as PRDX3 and MsrA, are responsible for increased reactive
oxygen species levels, decreased mitochondrial membrane potential, protein aggregation
and lens cell death, and further indicates that mitochondrial repair, protective, and
reducing systems play key roles in the progression of age-related cataract and other agerelated
diseases.

Purpose. To identify genes important for maintaining the specialized functions of lens epithelial and fiber cells. Methods. The expression profiles of 22,215 genes between human lens epithelial and fiber cells were analyzed using oligonucleotide microarray hybridization and RT-PCR. Selected genes were functionally clustered using the EASE bioinformatics software package. Results. Analysis of microarray hybridizations revealed 1430 transcripts that were significantly increased and 901 transcripts that were significantly decreased. Microarray data was confirmed using RT-PCR on 11 randomly selected genes. Functional clustering of the identified gene expression patterns revealed altered gene expression in cellular pathways including oxidative stress, cell proliferation, and apoptosis. The methionine sulfoxide reductase class of enzymes were further analyzed and demonstrated to be expressed throughout the human body, indicating a significant protective role. Conclusions. These data reveal novel and previously identified gene expression differences that provide insight into those mechanisms that may be important for lens cell differentiation.