Nuclear cataract caused by a lack of DNA degradation in the mouse eye lens.
The eye lens is composed of fibre cells, which develop from the epithelial cells on the anterior surface of the lens. Differentiation into a lens fibre cell is accompanied by changes in cell shape, the expression of crystallins and the degradation of cellular organelles. The loss of organelles is believed to ensure the transparency of the lens, but the molecular mechanism behind this process is not known. Here we show that DLAD ('DNase II-like acid DNase', also called DNase IIbeta) is expressed in human and murine lens cells, and that mice deficient in the DLAD gene are incapable of degrading DNA during lens cell differentiation--the undigested DNA accumulates in the fibre cells. The DLAD-/- mice develop cataracts of the nucleus lentis, and their response to light on electroretinograms is severely reduced. These results indicate that DLAD is responsible for the degradation of nuclear DNA during lens cell differentiation, and that if DNA is left undigested in the lens, it causes cataracts of the nucleus lentis, blocking the light path.
Nishimoto
Sogo
S
Department of Genetics, Osaka University Medical School, Osaka 565-0871, Japan. nagata@genetic.med.osaka-u.ac.jp
Kawane
Kohki
K
Watanabe-Fukunaga
Rie
R
Fukuyama
Hidehiro
H
Ohsawa
Yoshiyuki
Y
Uchiyama
Yasuo
Y
Hashida
Noriyasu
N
Ohguro
Nobuyuki
N
Tano
Yasuo
Y
Morimoto
Takeshi
T
Fukuda
Yutaka
Y
Nagata
Shigekazu
S
D000818:Animals; D002386:Cataract / Q000378:metabolism* / Q000473:pathology*; D002454:Cell Differentiation; D004247:DNA / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007908:Lens, Crystalline / Q000378:metabolism* / Q000473:pathology* / Q000503:physiopathology / Q000528:radiation effects; D008027:Light; D051379:Mice; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D012333:RNA, Messenger; D004247:DNA; D004706:Endodeoxyribonucleases; C019329:deoxyribonuclease II