Expression patterns of dystrophin products, especially of apodystrophin-1/Dp71, in the neural retina of Amphibian urodele Pleurodeles waltl

The expression patterns of the DMD (Duchenne Muscular Dystrophy) gene produ cts, especially of Dp71 (apodystrophin-1) were investigated by immunofluore scence and immunoblotting in the retina of the Amphibian urodele Pleurodele s waltl. H-5A3 monoclonal antibody (mAb), directed against the C-terminal r egion of dystrophin/utrophin, and 5F3 mAb, directed against the last31 amin o acids of dystrophin and specific of Dp71, were used. Western blot analyse s with H-5A3 mAb revealed distinct dystrophin-family isoforms in adult newt retinal extracts: a doublet 400-420 kDa, Dp260 isoform, a protein at about 120 kDa, and a diffuse zone at 70-80 kDa, which might correspond to Dp71. Reactivity with H-5A3 mAb appeared nearly restricted to the outer plexiform synaptic layer. On the other hand, Dp71-specific 5F3 mAb recognized trhee polypeptide bands at 70-80, 60-65 and 50-55 kDa in adult newt retina corres ponding most probably to alternative spliced isoforms of Dp71. In immunohis tochemistry by conventional epifluorescence microscopy, 5F3 labeling was ma inly observed in the plexiform layers, the outer nuclear layer, and the pho toreceptor inner segments, especially at the myoid regions. Analysis by con focal scanning laser microscopy (CSLM) revealed that 5F3 labeling was, in a ddition, present in the pigmented epithelium and the inner nuclear layer. F urthermore, CSLM showed that 5F3 staining at the myoids was concentrated at discrete domains underneath the plasma membrane. Our findings raised the q uestion concerning the functional significance of Dp71 isoforms, especially at the myoid where Dp71 was detected for the first time, although it occur red here highly expressed. Putative role(s) played in this retinal compartm ent and other ones by Dp71 and/or other dystrophin isoforms were discussed.