Dystrophin localization at presynapse in rat retina revealed by immunoelectron microscopy.

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Abstract

PURPOSE: It has been accepted that retinal dystrophin is localized in the outer plexiform layer (OPL) of the retina, but no electron microscopic evidence has been reported until now. Using immunoelectron microscopy, the authors investigate whether retinal dystrophin localizes at the presynaptic or postsynaptic membrane of synaptic regions. METHODS: Monoclonal antibody raised against human dystrophin C-terminus was used. Immunoblotting analysis was used for testing dystrophin protein in retinal tissues. Tissue preparations were stained with the immunofluorescence or immunoperoxidase method and were observed with light and electron microscopy. RESULTS: Immunoblotting analysis showed a molecular weight of band 420 kDa in the sodium dodecyl sulfate--polyacrylamide gel electrophoresis of the retinal tissues. Immunoelectron microscopy disclosed that retinal dystrophin was localized at the presynaptic membrane of synaptic regions in the OPL. CONCLUSIONS: Rat retinal dystrophin localizes at the presynaptic membrane in the OPL, suggesting that it may play some role in the neurotransmitter release of the photoreceptor cell.