Ethylnitrosourea-induced mutation in mice leads to the expression of a novel protein in the eye and to dominant cataracts.
A novel ENU-induced mutation in the mouse leading to a nuclear and zonular opacity of the eye lens (Aey1) was mapped to chromosome 1 between the markers D1Mit303 and D1Mit332. On the basis of the chromosomal position, the gamma-crystallin encoding gene cluster (Cryg) and the betaA2-crystallin encoding gene Cryba2 were tested as candidate genes. An A --> T mutation destroys the start codon of the Cryge gene in the mutants; this mutation was confirmed by the absence of a restriction site for NcoI in the corresponding genomic fragment of homozygous mutants. The next in-frame start codon is 129 bp downstream; this predicted truncated gammaE-crystallin consists of 131 amino acids, resulting in a molecular mass of 14 kD. However, another open reading frame was observed just 19 bp downstream of the regular Cryge start codon, resulting in a protein of 119 amino acids and a calculated molecular weight of 13 kD. Western blot analysis using polyclonal antibodies against gamma-crystallins or the novel Aey1-specific protein demonstrated the specific expression of the Aey1 protein in the cataractous lenses only; the truncated form of the gammaE-crystallin could not be detected. Therefore, it is concluded that the novel protein destroys the sensitive cellular structure of the eye lens.
Graw
J
J
GSF-National Research Center for Environment and Health, Institute of Mammalian Genetics, D-85764 Neuherberg, Germany. graw@gsf.de
Klopp
N
N
Löster
J
J
Soewarto
D
D
Fuchs
H
H
Becker-Follmann
J
J
Reis
A
A
Wolf
E
E
Balling
R
R
Habré de Angelis
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002386:Cataract / Q000139:chemically induced* / Q000235:genetics*; D003062:Codon; D003433:Crosses, Genetic; D003459:Crystallins / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D005123:Eye / Q000378:metabolism*; D005260:Female; D005819:Genetic Markers; D006239:Haplotypes; D007908:Lens, Crystalline / Q000473:pathology; D008297:Male; D051379:Mice; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009153:Mutagens; D009154:Mutation; D016366:Open Reading Frames; D016133:Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid; D012984:Software
D003062:Codon; D003459:Crystallins; D005819:Genetic Markers; D009153:Mutagens