| Research Abstract |
We have demonstrated through remodeling of the glycosyltrasferase machineries in human pre-B leukemia cells that cell surface sialyl-LeX (sLeX) antigen expression level is controlled by core 2 N-acetylglucosaminyltransferase (C2GnT) gene. In addition, we have revealed the followings.
1. sLeX antigen is not expressed on every protein but expressed on a specific core glycoprotein with molecular size of l5OkDa (gp 150). sLeX antigen determinants are expressed at the termini of 0-linked oligosaccharide chains of gplSO.
2. Analyzing transcription regulation mechanism of C2GnT expression by luciferase assay, EMSA, and RNA blotting, we have demonstrated the followings.
(1) Among three TATA boxes in the C2GnT transcription regulation area, a deletion mutant containing the most proximate -182 TATA to the transcription initiation site showed the highest luciferase activity.
(2) C2GnT gene expressing cells had 10-fold transient transcription activity of the non-expressing cells. Transient transcription activity was down-regulated to 1/10 by inhibiting C2GnT gene expression among cell differentiation. These are in a good agreement with changes of C2GnT message, C2GnT enzyme activity, and cell surface sLeX antigen expression levels.
(3) Involved transcription factor binding sites are GATA, NF-IL6, and Spi. The expression of GATA3, NF-1L6, C/EBPgamma, Sp3, and Sp4 genes correlated with C2GnT gene expression level.
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