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H. Fong, M. Y. Lin, H. Kochounian, R. E. Moore, T. D. Lee, N. Rao; Human RGR-d Splice Isoform in Bruch's Membrane. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3786.
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© ARVO (1962-2015); The Authors (2016-present)
Human retina and pigment epithelium (RPE) express a relatively abundant mRNA that encodes an extraneous splice isoform of the RPE retinal G protein-coupled receptor (RGR) opsin. In this study, we investigate this exon-skipping RGR splice isoform (RGR-d) in separated neural retina and RPE cells of human donors at various ages.
We used mass spectrometry, sensitive Western blot assay, immunohistochemical localization and amplification of cDNA to analyze RGR-d.
We have detected the RGR-d protein in the neural retina of all donors analyzed by sensitive Western blot assay. Mass spectrometric analysis of the immunoreactive proteins independently confirmed the presence of RGR-d. In contrast, RGR-d protein in the RPE of most donors was barely detectable by Western blot assay, even though expression of RGR-d mRNA was confirmed by amplification of RGR-d transcripts in both the RPE and neural retina. Immunohistochemical localization studies revealed that the RGR-d epitope is present near the basal boundary of RPE cells and primarily in the extracellular areas of Bruch’s membrane, adjacent choriocapillaris and intercapillary region of both young and older donors. Positive immunostaining was seen in the drusen found in older individuals.
These results indicate that after RGR-d is synthesized, the RGR-d epitope is released at the basal surface of the RPE and deposited into Bruch’s membrane in human eyes throughout adult life.
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