Regulation of mouse kidney tubular epithelial cell-specific expression of core 2 GlcNAc transferase

A mouse gene, Gsl5, controls the expression of Gal beta1-4(Fuc alpha1-3)Glc NAc beta1-6(Gal beta1-3)Gb(4)Cer and its precursor glycolipids in the kidne y by regulating transcription of beta -1,6-GlcNAc transferase. Here we repo rt that Gsl5 controls the expression of the core 2 structure [GlcNAc beta1- 6(Gal beta1-3)GalNAc alpha1-Ser/Thr] of glycoproteins as well as the glycol ipid, GlcNAc beta1-6(Gal beta1-3)GalNAc beta1-3Gal alpha1-4Gal beta1-4Glc b etal-ceramide. Immunohistochemical studies using an anti-(core 2-Le(x)) mon oclonal antibody demonstrated that lysosome-like vesicles of proximal tubul e cells were clearly stained in a Gsl5 wild type mouse, but not in a Gsl5 m utant strain of mice. Western blotting of microsomal fractions of kidney ti ssue with the same antibody confirmed the histological findings. rn situ hy bridyzation with an antisense probe to the kidney-specific mRNA demonstrate d that the mRNA is localized at proximal tubule-cells in the cortex adjacen t to the medulla, but not detected in glomeruli nor in collecting duct cell s in the medulla. The results obtained by immunohistological staining and i n situ hybridyzation are compatible and lead to the conclusion that the kid ney specific mRNA is expressed in a proximal tubular cell specific manner a nd produces core 2 GlcNAc transferase responsible for the production of gly coproteins localized at vesicles in the proximal tubular cells. Glycosylati on regulated by Gsl5 gene may modify functions of membrane glycoproteins in proximal tubular cells.