Developmental Change of Distribution of β-Galactoside α2,6- Sialyltransferase mRNA in Rat Retina

Abstract

A substantial change in the glycoconjugates of the rat interphotoreceptor matrix (IPM) has recently been shown to occur between post-natal day (P) 14 and P16 in rat retinas using lectin histochemistry. This suggests that the sialic acid content on the terminus of N-glycoside linked carbohydrate chains of the IPM increases between P14 and P16. In the present study, to test this hypothesis, we examined the developmental change of distribution of β-galactoside α2,6-sialyltransferase mRNA in rat retina using in situ hybridization histochemistry. C-DNA of rat α2,6-sialyltransferase was isolated by PCR and cloned into the polylinker site of Bluescript KS (+), Antisense and sense RNA probes were labelled with digoxigenin-UTP by in vitro transcription with T3 and T7 RNA polymerases, respectively. Paraffin sections of rat retinas between P12 and P42 were incubated with the antisense or sense RNA probes. Specific labelling with the antisense probe was observed strongly in the cytoplasm of all ganglion cells and weakly in partial cells of the inner nuclear layers throughout the examined postnatal days. A remarkable change was observed in the photoreceptor cells between P14 and P16. Hybridization signals of the outer nuclear layer was observed from P14, while those of the inner segments were detected on P16 and thereafter. The α2,6-sialyltransferase newly expressed in the inner segments on P16 appears to sialylate the Galβ1, 4GlcNAc residue of N-glycosidically linked glycoconjugates of the IPM, resulting in the change of lectin staining profiles.