A new model for assessing proteolysis in the intact mouse lens in organ culture.
OBJECTIVE
To develop a new method to investigate proteolysis in the intact lens in organ culture.


METHODS
Intact mouse lenses were assayed at regular intervals for proteolytic activity using fluorogenic peptide substrates +/- addition of ionomycin. Specific inhibitors were used to determine the activity of calpains, the proteasome and acid lysosomal enzymes.


RESULTS
Significant levels of proteolytic activity were present in the intact lens. Proteolysis was stimulated by ionomycin. Preincubation with an inhibitor to the proteasome significantly decreased proteolysis whereas inhibitors of calpain and acid lysosomal enzymes did not.


CONCLUSIONS
This study indicates that in the intact mouse lens in culture, the proteasome is an important protease. Its activity is at least partially regulated by calcium.
Petersen
A
A
Institute of Anatomy and Cell Biology, University of Göteborg, Göteborg, Sweden. Anne.Petersen@anatcell.gu.se
Zetterberg
M
M
Sjöstrand
J
J
Karlsson
J-O
JO
D000818:Animals; D002154:Calpain / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D005260:Female; D005456:Fluorescent Dyes; D015759:Ionomycin / Q000494:pharmacology; D007908:Lens, Crystalline / Q000187:drug effects / Q000201:enzymology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008954:Models, Biological; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009924:Organ Culture Techniques; D011480:Protease Inhibitors / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex
D005456:Fluorescent Dyes; D009097:Multienzyme Complexes; D011480:Protease Inhibitors; D015759:Ionomycin; D002154:Calpain; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex