Connexin expression in the retina

Here, we review recent results from our laboratory on connexin expression i n mouse retina in the context of previous results with other vertebrate spe cies. In mouse retina, four different connexin proteins were detected by im munoblot and immunofluorescence: connexin (Cx)-36, -37, -43 and -45. Cx36 a nd Cx45 immunoreactive signals were found in the inner and outer plexiform layer, both of which are known to show interneuronal gap junctions. Cx43 wa s detected in the ganglion cell layer, presumably in astrocytes, where it a ppeared to be colocalized with glial fibrillary acid protein. Cx37 was expr essed in retinal endothelial cells. Additionally, Cx26, -31, -32 and -40 mR NAs were detected in retina by RT-PCR but none of the corresponding protein s were found. In order to exclude cross reactions of the corresponding anti bodies, retinae from targeted connexin-deficient mice (Cx31 -/-, Cx32 -/- a nd Cx40 -/-) were used as negative controls for immunoblot and immunofluore scence analyses of wild-type retina. Further detailed investigation of cell type specific connexin expression in the mouse retina will be necessary fo r functional analyses of targeted mouse mutants with defects in connexins e xpressed in retinal neuronal cells. (C) 2000 Elsevier Science B.V. All righ ts reserved.