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G. Dvoriantchikova, D. Ivanov, V.I. Shestopalov; Expression and Localization of Pannexins in the Retina . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5498.
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Retinal cells perceive and transfer visual information to the brain and are known to form several types of electrical junctions to communicate and synchronize their rhythmic activity. Importantly, analysis of the retinas in the Cx36 and Cx45 deficient mice indicated presence of an unknown parallel pathway of electrical coupling between these neurons. Recent characterization of pannexins, a novel gap junction–like protein family, suggests that they are candidates for such a pathway. In this study we examined mouse retina for expression of Pannexins 1 and 2 and characterized localization of Panx1 protein across the retina.
We used RT–PCR and in situ hybridization to examine the expression pattern of Panx1 and Panx2 in murine retina. Immunohistochemistry and Western Blot with newly developed antibodies were utilized to characterize cellular localization of the Panx1 and its isoforms in this tissue. To examine pannexin expression in the purified retinal ganglion cells (RGCs), we employed the immunopanning technique.
Expression of the genes encoding Panx1 and Panx2 members of the pannexin family of gap junction–like proteins was demonstrated in the retina by in situ hybridization and quantitative RT–PCR. Our results showed that Panx2 was expressed at a higher level than Panx1 in adult retinas. Both pannexins were enriched in retinal ganglion cells relative to the rest of the retina. Using newly developed antibodies we showed Panx1 accumulation in ganglion and inner nuclear cell layers. In good agreement with Panx1–specific immunostaining in cultured cells, Panx1 immunoreactivity in RGCs localized to the cytoplasm and cellular processes. Western blot data revealed two isoforms, a 45 kDa cytosolic isoform and a 55 kDa isoform most likely associated with cell membranes.
Our results indicated that Panx1 and Panx2 are abundantly expressed in the retina. Both proteins co–localized with RGCs and amacrine cells and might, along with connexins, contribute to the electrical coupling between these retinal neurons.
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