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N. Piri, Y. Munemasa, J. M. K. Kwong, J. Caprioli; Expression of the Rna Binding Proteins, Rbpms and Rbpms2, in the Retina Is Localized to Ganglion Cells. Invest. Ophthalmol. Vis. Sci. 2008;49(13):771.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize expression of the RNA binding proteins, Rbpms and its paralog Rbpms2, in the retina as potential markers for retinal ganglion cells (RGCs).
To localize Rbpms and Rbpms2 mRNA expression in the retina, in situ hybridization with sense and anti-sense riboprobes was performed. Rbpms protein expression was analyzed by immunohystochemistry with antibodies generated against 22 aa polypeptide GGKAEKENTPSEANLQEEEVR located in the N-terminal of the protein. The expression of Rbpms and Rbpms2 genes in various rat tissues was analyzed with semi-quantitative RT-PCR.Retrograde RGC labeling was performed with Fluorogold (FG) applied to the surface of both superior colliculi. Optic nerve transection (ONT) was performed on adult male Wistar rats.
Rbpms- and Rbpms2-positive in situ signals were localized primarily to irregularly shaped cells in the ganglion cell layer (GCL) of the retina. Relatively weak staining was observed in the inner nuclear layer. Rbpms- and Rbpms2-positive cells in GCL were co-localized with FG-labeled RGCs. Rbpms- and Rbpms2-expressing cells were present more densely in the posterior region than in the periphery, which is consistent with the RGC distribution in the rat retina. Almost no Rbpms- or Rbpms2-positive and very few FG-labeled cells were detected by in situ hybridization in axotomized retinas with approximately 90-95% RGC loss. Consistent with the in situ results, RT-PCR showed a dramatic decrease in mRNA level of these genes after ONT compared to controls. With respect to protein expression, Rbpms antibodies reacted with cells in the GCL and were colocalized with FG-labeled RGCs. Outside the retina, abundant expression of these genes was observed in the heart, kidney, liver and lung and much lower in the cerebellum and cortex.
Our data indicate that Rbpms- and Rbpms2 are predominantly expressed in RGCs of the rat retina and therefore could serve as specific markers for these cells. The functions of these genes in RGCs are under investigation.
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