Elevated intraocular pressure, optic nerve atrophy, and impaired retinal development in ODAG transgenic mice.
OBJECTIVE
In an earlier study, a cDNA was cloned that showed abundant expression in the eye at postnatal day (P)2 but was downregulated at P10; it was named ODAG (ocular development-associated gene). Its biological function was examined by generating and analyzing transgenic mice overexpressing ODAG (ODAG Tg) in the eye and by identifying ODAG-binding proteins.


METHODS
Transgenic mice were generated by using the mouse Crx promoter. EGFP was designed to be coexpressed with transgenic ODAG, to identify transgene-expressing cells. Overexpression of ODAG was confirmed by Northern and Western blot analysis. IOP was measured with a microneedle technique. The eyes were macroscopically examined and histologically analyzed. EGFP expression was detected by confocal microscope. Proteins associated with ODAG were isolated by pull-down assay in conjugation with mass spectrometry.


RESULTS
Macroscopically, ODAG Tg exhibited gradual protrusion of the eyeballs. The mean IOP of ODAG Tg was significantly higher than that of wild-type (WT) littermates. Histologic analysis exhibited optic nerve atrophy and impaired retinal development in the ODAG Tg eye. EGFP was expressed highly in the presumptive outer nuclear layer and weakly in the presumptive inner nuclear layer in the ODAG Tg retina. Rab6-GTPase-activating protein (Rab6-GAP) and its substrate, Rab6, were identified as ODAG-binding proteins.


CONCLUSIONS
Deregulated expression of ODAG in the eye induces elevated intraocular pressure and optic nerve atrophy and impairs retinal development, possibly by interfering with the Rab6/Rab6-GAP-mediated signaling pathway. These results provide new insights into the mechanisms regulating ocular development, and ODAG Tg would be a novel animal model for human diseases caused by ocular hypertension.
Sasaki
Takaaki
T
Department of Developmental Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan.
Watanabe
Wataru
W
Muranishi
Yuki
Y
Kanamoto
Takashi
T
Aihara
Makoto
M
Miyazaki
Kazuko
K
Tamura
Hiroki
H
Saeki
Tadashiro
T
Oda
Hideaki
H
Souchelnytskyi
Nazariy
N
Souchelnytskyi
Serhiy
S
Aoyama
Hirohiko
H
Honda
Zen-ichiro
Z
Furukawa
Takahisa
T
Mishima
Hiromu K
HK
Kiuchi
Yoshiaki
Y
Honda
Hiroaki
H
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D050982:GATA1 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007429:Intraocular Pressure; D013058:Mass Spectrometry; D051379:Mice; D008822:Mice, Transgenic; D009798:Ocular Hypertension / Q000235:genetics* / Q000473:pathology; D009896:Optic Atrophy / Q000235:genetics* / Q000473:pathology; D011993:Recombinant Fusion Proteins; D012164:Retinal Diseases / Q000235:genetics* / Q000473:pathology; D020691:rab GTP-Binding Proteins
D050982:GATA1 Transcription Factor; C494689:Gata1 protein, mouse; C094135:Rab6 protein; D011993:Recombinant Fusion Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D020691:rab GTP-Binding Proteins