Characterization of a mutation in the lens-specific MP70 encoding gene of the mouse leading to a dominant cataract

Jochen Graw, Jana Löster, Dian Soewarto, Helmut Fuchs, Birgit Meyer, André Reis, Eckhard Wolf, Rudi Balling, Martin Hrabé de Angelis

Research output: Contribution to journalArticlepeer-review

46 Scopus citations

Abstract

During an ethylnitrosourea mutagenesis screen. Aey5, a new mouse mutation exhibiting an autosomal dominant congenital cataract was isolated. The cataractous phenotype is visible at the eye opening and progresses to a nuclear and zonular cataract at 2 months of age with no difference in onset or severity between heterozygous and homozygous mutants. Histological analysis revealed that fiber cell differentiation continues at the lens bow region, but the cell nuclei do not degrade normally and remain in the deeper cortex. Further, the lens nucleus has clefts of various sizes while the remainder of the eye was morphologically normal. The mutation was mapped to chromosome 3 between the markers D3Mit101 and D3Mit77 near the connexin encoding genes Gja5 and Gja8. Sequence analysis revealed no differences in the Gja5 gene, but identified a T→C mutation at position 191 in the Gja8 gene, which was confirmed by an additional Mva12691 restriction site in the genomic DNA of homozygous mutants. This mutation results in Val→Ala substitution at codon 64 of connexin50 (Cx50) also known as lens membrane protein 70 (MP70). Aey5 represents the second dominant mouse cataract mutant affecting Cx50, a membrane protein preferentially expressed in the lens. Since both mutations affect similar regions in the first extracellular domain this region appears to be critically important for its function in lens transparency.

Original languageEnglish
Pages (from-to)867-876
Number of pages10
JournalExperimental Eye Research
Volume73
Issue number6
DOIs
StatePublished - 2001
Externally publishedYes

Keywords

  • Cataract
  • Connexin50
  • DNA
  • Gja8
  • MP70
  • Mouse
  • Sequence analysis

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