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Published on: November 19, 2011
Methionine sulfoxide reductase A: Structure, function and role in ocular pathology.
Parameswaran G Sreekumar1, David R Hinton, Ram Kannan
1Parameswaran G Sreekumar, David R Hinton, Ram Kannan, Arnold and Mabel Beckman Macular Research Center, Doheny Eye Institute, Los Angeles, CA 90033, United States.
World Journal of Biological Chemistry
|September 13, 2011
Summary
Methionine sulfoxide reductases (Msrs) protect cells from oxidative stress. MsrA, particularly in retinal pigment epithelial cells, interacts with alpha-crystallins to prevent cell damage and may offer therapeutic targets for degenerative diseases.
Area of Science:
- Biochemistry
- Cell Biology
- Ophthalmology
Background:
- Methionine is susceptible to oxidation by reactive oxygen species, forming methionine sulfoxide.
- Methionine sulfoxide reductases (Msrs) are enzymes that reduce methionine sulfoxide back to methionine.
- MsrA is abundant in ocular tissues, including retinal pigment epithelial (RPE) cells, and protects against oxidative stress.
Purpose of the Study:
- To investigate the role of MsrA in cellular protection, particularly in the context of oxidative stress and age-related macular degeneration.
- To explore the interaction of MsrA with other proteins, such as alpha-crystallins, and its functional implications.
- To understand the regulation of MsrA and MsrB2 expression in human RPE cells under hypoxic conditions.
Main Methods:
- Localization studies of MsrA in ocular tissues.
- Analysis of MsrA function through overexpression and knockdown experiments, assessing cell survival and mitochondrial involvement.
- Investigation of protein-protein interactions, specifically MsrA with alpha-crystallins.
- Examination of MsrA and MsrB2 expression under chemically induced hypoxia in RPE cells.
Main Results:
- MsrA overexpression enhances cell resistance to death, while MsrA knockdown reduces cell survival, mediated by mitochondria.
- MsrA interacts with alpha-crystallins, which are crucial for protein folding and cell survival; methionine oxidation in alpha-crystallins impairs their chaperone function.
- MsrA co-localizes with alphaA and alphaB crystallins in retinal samples from age-related macular degeneration patients.
- Hypoxia regulates MsrA and MsrB2 expression in human RPE cells.
Conclusions:
- MsrA is a critical enzyme for cell and tissue protection against oxidative stress, particularly in the eye.
- The interaction of MsrA with proteins like alpha-crystallins is vital for maintaining cellular function and preventing damage.
- MsrA and its interactions represent potential therapeutic targets for preventing or treating degenerative diseases.
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