Phototransduction in a transgenic mouse model of Nougaret night blindness.
The Nougaret form of dominant stationary night blindness is linked to a G38D mutation in the rod transducin-alpha subunit (Talpha). In this study, we have examined the mechanism of Nougaret night blindness using transgenic mice expressing TalphaG38D. The biochemical, electrophysiological, and vision-dependent behavioral analyses of the mouse model revealed a unique phenotype of reduced rod sensitivity, impaired activation, and slowed recovery of the phototransduction cascade. Two key deficiencies in TalphaG38D function, its poor ability to activate PDE6 (cGMP phosphodiesterase) and decreased GTPase activity, are found to be the major mechanisms altering visual signaling in transgenic mice. Despite these defects, rod-mediated sensitivity in heterozygous mice is not decreased to the extent seen in heterozygous Nougaret patients.
Moussaif
Mustapha
M
Department of Physiology and Biophysics, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA.
Rubin
William W
WW
Kerov
Vasily
V
Reh
Rebecca
R
Chen
Desheng
D
Lem
Janis
J
Chen
Ching-Kang
CK
Hurley
James B
JB
Burns
Marie E
ME
Artemyev
Nikolai O
NO
D000818:Animals; D015153:Blotting, Western / Q000379:methods; D003623:Dark Adaptation / Q000502:physiology; D004195:Disease Models, Animal; D004596:Electroretinography / Q000379:methods; D005136:Eye Proteins / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009755:Night Blindness / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D010775:Photic Stimulation / Q000379:methods; D012160:Retina / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D017948:Retinal Rod Photoreceptor Cells / Q000503:physiopathology; D012684:Sensory Thresholds / Q000502:physiology; D015293:Transducin / Q000235:genetics*; D014785:Vision, Ocular / Q000235:genetics*
D005136:Eye Proteins; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D015293:Transducin