Transcriptional regulation of the human Sia-alpha2,3-Gal-beta1,4-GlcNAc-R : alpha2,8-sialyltransferase (hST8Sia III) by retinoic acid in human glioblastoma tumor cell line

摘要

In this study, we have shown the transcriptional regulation of the human Sia-alpha2,3-Gal-beta 1,4-GlcNAc-R:alpha2,8-sialyltransferase (hST8Sia III) induced by retinoic acid (RA), a potent neuronal cell regulator in glioblastoma cell line (U-87MG). The induction of hSTSSia III by RA is regulated at the transcriptional level in a dose- and time-dependent manner, as evidenced by reverse transcription-polymerase chain reaction (RT-PCR). To elucidate the mechanism underlying the regulation of hST8Sia III gene expression in RA-stimulated U-87MG cells, we characterized the promoter region of the hST8Sia III gene. Functional analysis of the 5-flanking region of the hST8Sia III gene by the transient expression method showed that the -1194 to -816 region, which contains a retinoic acid nucleic receptor (RAR) at -1000 to -982, functions as the RA-inducible promoter in U-87MG cells. Site-directed mutagenesis indicated that the RA binding site at -996 to -991 is crucial for the RA-induced expression of the hSTSSia III in U-87MG cells. In addition, the transcriptional activity of hST8Sia III induced by RA in U-87MG cells was strongly inhibited by SP600125, c-Jun N-terminal Kinase (JNK) inhibitor, as determined by RT-PCR and luciferase assay of hST8Sia III promoter containing the -1194 to -816 regions. These results suggest that RA markedly modulates transcriptional regulation of hSTSSia III gene expression through JNK signal pathway in U-87MG cells. (c) 2006 Elsevier B.V. All rights reserved.