Proteasome activity in human lens nuclei and correlation with age, gender and severity of cataract.
OBJECTIVE
The aim of this study was to measure proteasome activity in human lens nuclei resulting from cataract surgery and in different regions of donor lenses.


METHODS
The chymotrypsin-like, the trypsin-like and the peptidylglutamyl-peptide hydrolysing activities of the proteasome were studied using synthetic flourogenic substrates.


RESULTS
Proteasome activity did not show any correlation with age of the patients or with gender. Increased opacification of the lens nucleus, as estimated prior to surgery using a 4-grade scale, was significantly correlated with decreased activity of all peptidase activities in the insoluble fraction. In the donor lenses, all peptidase activities were highest in the epithelium and decreased rapidly towards the nucleus.


CONCLUSIONS
The present study demonstrates that proteasome activity is preserved in the nucleus of lenses from elderly individuals, although a decrease can be seen with cataract formation. This finding may be of importance for elucidating the mechanism behind the formation of nuclear cataract.
Zetterberg
Madeleine
M
Institute of Clinical Neuroscience, Section of Ophthalmology, Medical Faculty, Göteborg University, Göteborg, Sweden. madeleine.zetterberg@anatcell.gu.se
Petersen
Anne
A
Sjöstrand
Johan
J
Karlsson
Jan
J
D000375:Aging / Q000378:metabolism*; D002386:Cataract / Q000201:enzymology / Q000503:physiopathology*; D002918:Chymotrypsin / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D010450:Endopeptidases / Q000378:metabolism; D006801:Humans; D007907:Lens Nucleus, Crystalline / Q000201:enzymology*; D009097:Multienzyme Complexes / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D012720:Severity of Illness Index; D012727:Sex Characteristics; D014357:Trypsin / Q000378:metabolism
D009097:Multienzyme Complexes; D010450:Endopeptidases; D010447:Peptide Hydrolases; D002918:Chymotrypsin; D014357:Trypsin; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; C114177:peptidylglutamylpeptide hydrolase