Cell-Type-Specific Expression of Panx1 in the Mouse Retina

Abstract

Purpose: : Pannexins make up a family of vertebrate proteins whose functional role is only just emerging. Three pannexins have been described in the rodent genome: Panx1, Panx2 and Panx3. Their topology is similar to that of connexin hemichannels, which dock to each other to form a pore between adjacent cells. Panx1 is known to form channels, connecting the cytoplasm with the extracellular space, allowing the exchange of small molecules. It is still not clear whether pannexin single membrane channels also form functional intercellular gap junction channels. The channel properties of Panx1 are distinct from those of connexins and are more suited for transmembrane transport of Ca2+ and ATP. Previous studies have shown that Panx1 is expressed in various neuronal tissues, including the retina (Dvoriantchikova et al., 2006). In this study we examined the distribution of Panx1 in the mouse retina using multiple approaches.

Methods: : We used RT-PCR to identify Panx1 expression in the mouse retina. We analyzed the cell-type-specific Panx1 mRNA expression using fluorescence in situ hybridization (FISH). For detection of Panx1 proteins in the mouse retina, we used anti-Panx1 antibodies. We demonstrated the retinal specificity of the antibodies by Western blot and immunohistochemistry on transgenic Panx1 knock-out mice.

Results: : Consistent with previous studies, we identified Panx1 expression in the mouse retina. Panx1 mRNA and proteins were localized in different cell types in the mouse retina, in particular in the membrane of certain bipolar cells and in dendrites of amacrine cells.

Conclusions: : These findings show that Panx1 is expressed in different cell-types in the mouse retina, in particular in the membrane of certain bipolar cells and in dendrites of amacrine cells.

Keywords: cell adhesions/cell junctions • cell membrane/membrane specializations • protein structure/function