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Antioxidants May Protect Pathway That Stops
Cataracts
Aug. 22, 2005 - When damaged proteins gather within
the eye’s lens, cloudiness occurs. These opacities are called cataracts.
The protein buildup could also lead to age-related macular degeneration.
Efficient removal of denatured proteins within the eye lens—or their
repair by other proteins—is crucial for maintenance of lens
transparency.
Researchers at the USDA’s Laboratory for Nutrition
and Vision Research have found that an accumulation of damaged proteins
indicates a breakdown of the protective ubiquitin-proteasome pathway. It
is an important alliance between a protein-degrading enzyme, called a
proteasome, and a smart, omnipresent protein referred to as ubiquitin.
This pathway helps balance the concentration of proteins within cells.
This balance is important because some proteins
need to be cleared from the body’s cells, for example, after having
become oxidized.
Antioxidants, such as vitamins C and E, and
antioxidant enzymes, such as superoxide dismutase and catalase, may play
an important role in protecting the pathway.
Within cells, ubiquitin identifies and attaches to
proteins that are ripe for degradation and removal. The resulting
“ubiquitin-conjugated proteins” latch onto the proteasome enzyme, which
degrades the proteins.
Allen Taylor, Fu Shang and colleagues were the
first to observe the pathway in cells within the eye’s lens, retina, and
cornea and have reported those findings in Experimental Eye Research,
The Journal of Biological Chemistry, Investigative Ophthalmology and
Visual Science, and other journals.
Taylor and Shang are at the Laboratory for
Nutrition and Vision Research, Jean Mayer USDA Human Nutrition Research
Center on Aging at Tufts University
For the complete article by Rosalie Marion Bliss,
Agricultural Research Service Information Staff, go to "A Pathway to
Clearer Vision" published in the
August 2005 issue of Agricultural Research magazine.
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