The ATF/CREB site is the key element for transcription of the human RNA methyltransferase like 1 (RNMTL1) gene, a newly discovered 17p13.3 gene

摘要

The human RNA methyltransferase like i gene (RNMTL1) is one of thirteen newly discovered geneswithin a 116 Kb segment of the chromosome 17p13.3 that suffers from a high frequent loss of heterozygosityin human hepatocellular carcinoma in China[1-5]. To understand the molecular mechanisms underlyingtranscription control of the RNMTL1 gene in human cancers, we decline using of the conventional approachwhere the cis-elements bound by the known transcription factors are primary targets, and carried out thesystematic analyses to dissect the promoter structure and identify/characterize the key cis-elements thatare responsible for its strong expression in cell. The molecular approaches applied included 1, the primerextension for mapping of the transcription starts; 2, the transient transfection/reporter assays on a largenumber of deletion and site-specific mutants of the promoter segment for defining the minimal promoterand the crucial elements within; and 3, the electrophoresis mobility shift assay with specific antibodies forreconfirming the nature of the transcription factors and their cognate cis-elements. We have shown that theinteraction of an ATF/CREB element (-38 to -31) and its cognate transcription factors play a predominantrole in the promoter activity of the RNMTL1 gene. The secondary DNA structures of the ATF/CREBelement play a more vital role in the protein-DNA interaction. Finally, we reported a novel mechanismunderlying the YY1 mediated transcription repression, namely, the ATF/CREB dependent transcription-repression by YY1 is executed in absence of its own sequence-specific binding.