Aging and cellular maturation cause changes in ubiquitin-eye lens protein conjugates
The eye lens is a useful tissue for studying phenomena related to aging since it can be separated into differentially aged or matured zones. This work establishes correlations between ubiquitin-lens protein conjugating capabilities and age, as well as the stage of maturation of bovine lens tissue. W...
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Published in | Archives of biochemistry and biophysics Vol. 276; no. 1; pp. 32 - 37 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
San Diego, CA
Elsevier Inc
1990
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | The eye lens is a useful tissue for studying phenomena related to aging since it can be separated into differentially aged or matured zones. This work establishes correlations between ubiquitin-lens protein conjugating capabilities and age, as well as the stage of maturation of bovine lens tissue. When exogenous
125I-ubiquitin was combined with supernatants of epithelial (least mature), cortex, and core (most mature) tissue, ATP-dependent conjugation of
125I-ubiquitin to lens proteins was most effective with the epithelial tissue preparation. Conjugate formation was greatest when lenses were obtained from young animals. Supernatants from cultured bovine lens epithelial (BLE) cells conjugated more
125I-ubiquitin to lens proteins than any tissue preparation. In all cases the predominant conjugates formed in these cell-free assays were of high molecular mass, although conjugates with masses in the 25–70 kDa range were also observed. Lens tissue and cultured BLE cell preparations were also probed with antibodies to ubiquitin to detect
in vivo ubiquitin-lens protein conjugates. There was more free ubiquitin and ubiquitin conjugates in tissue from young as compared with older lenses. The greatest levels of conjugates were observed in cultured BLE cells. Specificity in the ubiquitination system is indicated since some of the conjugates formed
in vivo appear identical to those formed in the cell-free assays and in reticulocytes using exogenous
125I-ubiquitin. Upon development and maturation of lens tissue (i.e., core as opposed to epithelium), there is accumulation of lower molecular mass conjugates. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0003-9861 1096-0384 |
DOI: | 10.1016/0003-9861(90)90006-K |