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D. Niculescu, A. Cooper, G. M. Acland, G. D. Aguirre, A. M. Komáromy; Analysis of Retinal Molecular Marker Expression in a Canine Model of Achromatopsia. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2986.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the expression of selected retinal gene products in a canine model of achromatopsia caused by a genomic deletion of CNGB3.
We performed immunohistochemical labeling on canine retinal tissues of CNGB3 null mutants, and normal controls, between 4 weeks and 4 years of age. This time period covers normal photoreceptor development as well as various stages of disease in canine achromatopsia. Previously, we showed that cone function is still present in affected dogs before 8 weeks of age. We used the following antibodies to label cone photoreceptors: red/green (L/M) cone opsin, blue (S) cone opsin, human cone arrestin (hCAR), and clusterin-like 1 protein (CLUL1). We labeled other retinal cells using antibodies against RPE65, rhodopsin, synaptophysin, protein kinase C and Goα, calbindin, D-28k, GABA, GFAP and glutamine synthetase. Antibodies against brain-derived neurotrophic factor and trkB receptor were also used.
Analysis of affected retinal tissues revealed that L/M and S cones were present throughout the time period covered in all retinal tissues. However, the observed L/M and S opsin expression patterns demonstrated an age-related decrease in cone numbers, and altered cone morphology in CNGB3 null mutants. Labeling of cone outer segments (OS) with CLUL1, a cone-specific protein, was the same in affected and non-affected tissues. Cone arrestin (hCAR) was detected in the OS but not inner segments (IS) of most affected cones; in contrast, both OS and IS of normal cones were labeled. In the normals, trkB was expressed in retinal ganglion cells and cone IS, and labeling intensity appeared to increase with age. In contrast, there was no labeling of cone IS with trkB in the affected retinas. We did not detect changes in expression of the other retinal molecular markers examined.
Cones were present at all disease stages studied, which may prove useful for future rescue attempts in achromatopsic dogs using gene therapy. In contrast to non-affected retinas, trkB was not expressed in cones of affected retinas, and mislocalization of cone arrestin was present in most cone IS. Most retinal molecular markers remain unchanged in dogs affected with achromatopsia.
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