Structure of the human allelic glutathione S-transferase-pi gene variant, hGSTP1 C, cloned from a glioblastoma multiforme cell line.
We recently reported the cloning of full-length cDNAs corresponding to mRNAs of three GST-pi genes, hGSTP1*A, hGSTP1*B and hGSTP1*C, as well as, the isolation of the full-length hGSTP1*C, of the human glutathione S-transferase-pi (GST-pi) gene that is characterized by a A-->G transition at +1404 in exon 5 and a C-->T transition at +2294 in exon 6. Although the promoter of the isolated gene was identical to that of the previously described GST-pi gene isolated from the MCF 7 and the HPB-ALL cell lines, both of which were hGSTP1*A, a number of structural differences were observed, including, nucleotide transitions, transversions, deletions and insertions, some of which created new restriction enzyme cleavage sites. A guanine insertion in the insulin response element, IRE, in intron 1 created an additional site for 5'-cytosine methylation. Seven repeat retinoic acid response element (RARE) consensus half sites, A(G)GG(T)TC(G)A at +1521 to +1644 were identified in the cloned hGSTP1*C. Five of the RARE half-sites had the minimal spacer nucleotide requirement for functionality and DNA mobility shift analysis with different pairs of the RARE half-sites and supershift studies using antibodies against RAR-beta showed significant binding of nuclear protein complexes from RA-treated cells to these RAREs. GST-pi gene expression was increased significantly in cells transfected with the GST-pi gene and treated with all-trans RA. These results contrast with those in a previous report in which RA was shown to suppress the GST-pi promoter, and indicate a complex mechanism of RA-mediated GST-pi gene regulation in tumor cells.
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Department of Experimental Pediatrics, University of Texas-MD Anderson Cancer Center, Houston 77030, USA.
Ali-Osman
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D000483:Alleles; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D003001:Cloning, Molecular; D016384:Consensus Sequence; D004273:DNA, Neoplasm / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D014644:Genetic Variation; D005909:Glioblastoma / Q000201:enzymology / Q000235:genetics; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase / Q000235:genetics*; D006801:Humans; D007527:Isoenzymes / Q000235:genetics*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D004273:DNA, Neoplasm; D007527:Isoenzymes; D014212:Tretinoin; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase