Document Detail

alpha-Crystallin binding in vitro to lipids from clear human lenses.
MedLine Citation:
PMID:  15967437     Owner:  NLM     Status:  MEDLINE    
The association of alpha-crystallin to lens membranes increases with age and cataract. Lipid compositional changes also occur with age, cataract, and diabetes. In this study we determined the influence of lipid compositional differences on the binding capacity of alpha-crystallin to lipid vesicles in vitro. Lipids were extracted from pools of human lenses from younger (22+/-4 y, n=30) and older (69+/-3 y, n=26) nondiabetic donors as well as from diabetics taking insulin (60+/-9 y, n=26) and diabetics not taking insulin (58+/-9 y, n=20). Diabetics were insulin dependent for an average of 6 years. Extracted lipids were extruded into large unilamellar vesicles. alpha-Crystallin was mixed with the lipid at 36 degrees C, allowed to bind for about 12 h, and centrifuged at 14,000 g. This centrifugal force was low enough to not pellet free alpha-crystallin but high enough to pellet the lipid and bound alpha-crystallin. alpha-Crystallin-lipid binding was characterized by comparing the amount alpha-crystallin in the pellets of samples with and without lipid. Protein was measured using an assay that minimized interference from lipids. Lipid composition was determined by 31P-NMR spectroscopy. The binding capacity of alpha-crystallin to lipids was 12, 19, 8.9, 17 microg bound/mg lipid for lens lipids extracted from younger, older, insulin-treated and nontreated diabetic donors, respectively. The amount of alpha-crystallin in the pellet (bound alpha-crystallin) was significantly lower for the lipids from the younger group of lenses, p=0.033 and insulin-treated group, p=0.006, compared with the older group of lenses. Higher binding capacity was associated with a higher relative amount of sphingolipid and lower relative amounts of phosphatidylethanolamine-related lipid and phosphatidylcholine. The binding capacity of alpha-crystallin to lens lipids, measured in vitro, increases with age and decreases in diabetic donors that were treated with insulin. Our data support the idea that with age and perhaps certain types of diabetes, more alpha-crystallin is bound to the membrane and serves as a condensation point to which other crystallins bind and then become oxidized.
Vahid Grami; Yernan Marrero; Li Huang; Daxin Tang; Marta C Yappert; Douglas Borchman
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Experimental eye research     Volume:  81     ISSN:  0014-4835     ISO Abbreviation:  Exp. Eye Res.     Publication Date:  2005 Aug 
Date Detail:
Created Date:  2005-08-05     Completed Date:  2005-09-29     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370707     Medline TA:  Exp Eye Res     Country:  England    
Other Details:
Languages:  eng     Pagination:  138-46     Citation Subset:  IM    
Department of Ophthalmology and Visual Science, Kentucky Lions Eye Center, University of Louisville, 301 E. Muhammad Ali Boulevard, Louisville, KY 40202, USA.
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MeSH Terms
Aging / metabolism
Diabetes Mellitus, Type 1 / metabolism
Diabetes Mellitus, Type 2 / metabolism
Lens, Crystalline / metabolism*
Magnetic Resonance Spectroscopy / methods
Membrane Lipids / metabolism*
Middle Aged
Phospholipids / metabolism
alpha-Crystallins / metabolism*
Grant Support
Reg. No./Substance:
0/Membrane Lipids; 0/Phospholipids; 0/alpha-Crystallins

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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