Calcium-activated proteolysis in the lens nucleus during selenite cataractogenesis

L. L. David, T. R. Shearer

Research output: Contribution to journalArticle

91 Scopus citations

Abstract

A single injection of 20 μmol sodium selenite/kg body weight in 10-day-old rats caused severe nuclear cataract within 4 days. By 4 days postselenite injection, nuclear calcium levels increased from 0.4 to 6.8 mmol/kg lens dry weight. The purpose of these experiments was to determine if this calcium increase was associated with proteolysis in the lens nuclear region. Sodium dodecyl sulfate polyacrylamide electrophoresis of lens nuclear proteins following selenite injection showed: loss of 30, 27, and 26 K molecular weight polypeptides in the soluble fraction, loss of 83, 52, 30, 27, and 26 K polypeptides in the insoluble fraction, and loss of the major 26 K membrane protein. Gel chromatography of nuclear soluble proteins indicated a decrease in β(H) and β(L) crystallins following selenite injection. Two-hour in vitro incubation of nuclear lens homogenates with calcium duplicated many of the proteolytic changes occurring in lenses in vivo following selenite injection. Calcium induced proteolysis in vitro was inhibited by EGTA, leupeptin, and iodoacetate but was not inhibited by phenylmethylsulfonyl fluoride. These properties are similar to calcium activated protease (CAP) from other tissues. Activation of CAP, and subsequent degradation of nuclear proteins, may be causes of selenite cataract.

Original languageEnglish (US)
Pages (from-to)1275-1283
Number of pages9
JournalInvestigative Ophthalmology and Visual Science
Volume25
Issue number11
StatePublished - 1984

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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