Modelling cortical cataractogenesis. XXIX. Calpain proteolysis of lens fodrin in cataract

• Published in: Biochemistry and molecular biology international Vol. 45; no. 5; p. 963
• Main Authors: Kilic, F, Trevithick, J R
• Format: Journal Article
• Language: English
• Published: England 01.08.1998
• Subjects: Amino Acid Sequence; Animals; Calcium - metabolism; Calpain - metabolism; Carrier Proteins - metabolism; Cataract - metabolism; Cataract - pathology; Culture Techniques; Cysteine Proteinase Inhibitors - pharmacology; Cytochalasin D - pharmacology; Fluoresceins; Fluorescent Dyes; Glucose - pharmacology; Glycoproteins - pharmacology; L-Lactate Dehydrogenase - metabolism; Lens Cortex, Crystalline - metabolism; Lens Cortex, Crystalline - pathology; Lens, Crystalline - metabolism; Lens, Crystalline - pathology; Microfilament Proteins - metabolism; Molecular Sequence Data; Organic Chemicals; Pyridinium Compounds; Rats
• ISSN: 1039-9712
• DOI: 10.1002/iub.7510450514

The relation between cataract and calpain proteolysis of lens fodrin was studied in two systems: elevated glucose (55.6 mM, diabetic model), and cytochalasin D (CD, 10(-2) mM, actin depolymerization-induced opacity model). Glucose treatment (48 h) caused a visible opaque layer and enzyme leakage, with a concomitant accumulation of ([Ca2+]i) around the lens equatorial cortex. CD caused both earlier and greater opacity and enzyme leakage than glucose. Lens fodrin digestion occurred in parallel with the timing and extent of calcium elevation. A calpain inhibitor peptide (CIP, 10(-2) mM) reduced the proteolysis of fodrin, opacity, and enzyme leakage in glucose-treated lenses but only partially retarded them in CD-treated lenses. These results suggest a mechanism in which calpain proteolysis of fodrin is a critical event in lens damage during opacification of cortical cataract.