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内容記述 |
N-linked sugar chains on glycoproteins are indispensable for the normal development. The expression of N-linked sugar chains is strictly regulated spatially and temporally, and tissue specific expression patterns of N-glycans are observed. Comparison of the mouse brain as well as the human brain revealed little variation among individuals of each species. However, molecular mechanisms that are responsible for the strict regulation of the N-linked sugar chains remain largely unknown. The expression of the N-glycans is based on the orchestrated action of many enzymes, glycosyltransferases and glycosidases, which catalyze biosynthesis and degradation of glycochains. The expression patterns of genes that encode these enzymes are, therefore, necessary to understand the regulatory mechanisms of N-glycan biosynthesis. In the present study, I developed a cDNA macroarray, with which expression of most of the glycosyltransferase and glycosidase genes can be analyzed at the same time. I chose this sensitive system because the expression levels of these genes were mostly too low to be analyzed by a microarray system. Using the cDNA macroarray system, I analyzed the gene expression patterns of more than 110 glycosyltransferases and glycosidases in the brain from 12-day mouse embryos, and in the brain, kidney, and liver from 12-week adult mice, and correlated them with the expression patterns of N-linked sugar chains in these tissues. The analyses revealed the tissue specific expression patterns of the glycosyltransferase and glycosidase genes as well as tissue specific N-glycan expression profiles. For example, whereas Golgi-mannosidase IB and polypeptide GalNAc Transferase I genes were equally expressed in these four tissues, α2, 8-sialyltransferase V and β1, 4-galactosyltransferase VI genes were highly expressed in the postnatal 12-week brain. mRNA amounts of some of the genes, which were differentially expressed in the four tissues were further verified by means of RT-PCR analyses. By comparing the gene expression and N-glycan expression profiles, I could obtain several new findings; bisecting structures were exclusively catalyzed by N-acetylglucosaminyltransferase III, and a core fucose is exclusively synthesized by fucosyltransferase VIII. In this study, I also compared the expression of the glyco-genes and N-linked sugar chains, and identified correlation between gene expression and N-linked sugar chains. For example, the gene expression of glucosidase I, glucosidase II and ER-mannosidase I was highly correlated Golgi-mannosidase IB with correlation coefficients (0.82, 0.74 and 0.80, respectively). Such coordinated expression could be necessary and important physiologically to biosynthesize the N-linked sugar chains smoothly and efficiently. cDNA macroarray system as well as high-throughput N-glycan analyzing system will provide significant information for the elucidation of the regulatory mechanisms and biological function of the N-linked sugar chains. |
要旨・審査要旨 / Abstract, Screening Result (228.8 kB)
