Cholesterol-derived bile acids enhance the chaperone activity of α-crystallins
Autor: | Toshimichi Shinohara, Christian J. Madson, Michael L. Mulhern, Jack J.-N. Liang, Shuhua Song |
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Jazyk: | angličtina |
Rok vydání: | 2011 |
Předmět: |
Cholagogues and Choleretics
medicine.drug_class Taurochenodeoxycholic acid Biology Biochemistry Bile Acids and Salts Taurochenodeoxycholic Acid chemistry.chemical_compound Crystallin Lens Crystalline medicine Animals Humans Protein Isoforms alpha-Crystallins Original Paper Bile acid Molecular Structure Cholesterol Ursodeoxycholic Acid Biological membrane Tauroursodeoxycholic acid Cell Biology Middle Aged Ursodeoxycholic acid eye diseases Recombinant Proteins Rats Blot chemistry sense organs medicine.drug Molecular Chaperones |
Popis: | Human lens membranes contain the highest cholesterol concentration of any known biological membranes, but it significantly decreases with age. Oxygenation of cholesterol generates numerous forms of oxysterols (bile acids). We previously showed that two forms of the bile acid components--ursodeoxycholic acid (UDCA) and tauroursodeoxycholic acid (TUDCA)--suppressed lens epithelial cell death and alleviated cataract formation in galactosemic rat lenses. We investigated whether these compounds also suppress the thermal aggregation of human lens crystallins. Total water-soluble (WS) proteins were prepared from human lenses, and recombinant human crystallins (αA-, αB-, βB2-, and γC-crystallin) were generated by a prokaryotic expression system and purified by liquid chromatography. The light scattering of proteins in the presence or absence of UDCA or TUDCA was measured using a spectrofluorometer set at Ex/Em = 400/400 nm. Protein blot analysis was conducted for detection of α-crystallins in the human lens WS proteins. High concentrations of UDCA and TUDCA significantly suppressed thermal aggregation of total lens WS proteins, which contained a low level of αA-/αB-crystallin. Spectroscopic analysis with each recombinant human lens crystallin indicated that the bile acids did not suppress the thermal aggregation of γC-, βB2-, αA-, or αB-crystallin. Combination of α-crystallin and bile acid (either UDCA or TUDCA) suppressed thermal aggregation of each individual crystallin as well as a non-crystallin protein, insulin. These results suggest that UDCA or TUDCA protects the chaperone activity of α-crystallin. It is believed that these two naturally occurring intermediate waste products in the lens enhance the chaperone activity of α-crystallin. This finding may lead to the development of UDCA and TUDCA as anticataract agents. |
Databáze: | OpenAIRE |
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