REGULATION OF THE BIOAVAILABILITY OF THIOREDOXIN IN THE LENS BY A SPECIFIC THIOREDOXIN-BINDING PROTEIN (TBP-2)*
| Autor: | Marjorie F. Lou, M. Rohan Fernando, Namal P.M. Liyanage |
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| Jazyk: | angličtina |
| Rok vydání: | 2007 |
| Předmět: |
Cell type
animal structures DNA Complementary Swine genetic processes Biological Availability macromolecular substances Biology Polymerase Chain Reaction Article law.invention Cellular and Molecular Neuroscience Thioredoxins law Gene expression Lens Crystalline Animals Humans RNA Messenger Cloning Molecular Gene Cells Cultured Regulation of gene expression cDNA library Binding protein Epithelial Cells Hydrogen Peroxide Sensory Systems Recombinant Proteins Ophthalmology enzymes and coenzymes (carbohydrates) Oxidative Stress Biochemistry Gene Expression Regulation Recombinant DNA health occupations Thioredoxin Carrier Proteins |
| Popis: | Thioredoxin (TRx) is known to control redox homeostasis in cells. In recent years, a specific TRx binding protein called thioredoxin binding protein-2 (TBP-2) was found in other cell types and it appeared to negatively regulate TRx bioavailability and thereby control TRx biological function. In view of the sensitivity of lens transparency to redox status, proper regulation of TRx bioavailability is of the utmost importance. This study was conducted to examine the presence and function of TBP-2 in human lens epithelial cells (HLE B3). We cloned human lens TBP-2 from a human cDNA library (GenBank accession number AY 594328) and showed that it is fully homologous to the human brain TBP-2 gene. The recombinant TBP-2 protein was partially purified and mass spectrometric analysis confirmed its sequence homology to that of brain TBP-2. Immunoprecipitates obtained from HLE B3 cells using anti-TRx and anti-TBP-2 antibodies showed the presence of TRx and TBP-2 in immunoprecipitates indicating the formation of a TRx-TBP-2 complex in vivo. Furthermore, under H(2)O(2)-stress conditions, TRx gene expression was transiently up-regulated while TBP-2 gene expression was inversely down-regulated as seen in both HLE B3 cells and in the epithelial cell layers from cultured pig lenses. Cells with overexpressed TBP-2 showed lower TRx activity, grew slower and were more susceptible to oxidative stress-induced apoptosis. This is the first report of the presence of a TRx-specific binding protein in the lens. Our data suggest that TBP-2 is likely a negative regulator for the bioavailability, and therefore, the overall function of TRx in the lens. |
| Databáze: | OpenAIRE |
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