Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5589515 | Gene | 2017 | 37 Pages |
Abstract
The human cytokine precursor ECRG4 has been associated with multiple physiological, developmental and pathophysiological processes involving cell proliferation, cell migration, innate immunity, inflammation, cancer progression and metastases. Although down-regulation of ECRG4 gene expression has been largely attributed to hypermethylation of CpG islands in the 5'untranslated region of the ECRG4 promoter, the mechanisms that underlie the dynamics of its regulation have never been systematically described. Here we show that the ECRG4 gene is widely expressed in human tissues and report that its core promoter lies between the â 780 to + 420 base pairs relative to the ATG start codon of the ECRG4 open reading frame. This sequence, which contains several CpG islands, also includes multiple overlapping Sp1 consensus binding sequences and a putative binding site for NF-kB activation. 5â²RACE of mRNA derived from human leukocytes shows that ECRG4 transcription initiates from the guanidine at â 11 from the initiation ATG of the ECRG4 open reading frame. While there is no canonical TATA- or CAAT-boxes proximal to this translational initiation site, there is a distal TATA-sequence in the 5â²UTR. This region was identified as the sequence targeted by hypermethylation because in vitro methylation of plasmids encoding the ECRG4 promoter abolish promoter activity and the treatment of Jurkat cells (which naturally express ECRG4) with the methylation inhibitor 5-AzaC, increases endogenous ECRG4 expression. Because ChIP assays show that Sp1 binds the ECRG4 promoter, that forced Sp1 expression trans-activates the ECRG4 promoter and Sp1 inhibition with mithramycin inhibits ECRG4 expression, we conclude that the dynamic positive and negative regulatory elements controlling ECRG4 expression include a counter regulation between promoter methylation and Sp1 activation.
Keywords
5-azaCEGFRGSPRPMIHUVECPMNHypermethylation5-AzacytidineORFGFAPTISPBMCACTHDMEMspecific protein-1transcription initiation sitesDulbecco's modified Eagle's mediumSp1Gene-specific primerEDTAEthylene diamine tetra acetic acidribonucleic acidRNAchromatin immunoprecipitationrapid amplification of cDNA endsbase pairreverse transcriptionHuman umbilical vein endothelial cellPeripheral blood mononuclear cellJurkat cellsPolymorphonuclear cellscytomegalovirusCMVnuclear factorSp1 transcription factoropen reading frameluciferaseRaceRoswell Park Memorial Institute mediumpolymerase chain reactionPCRGlial fibrillary acidic proteinPromoterChoroid plexusCHiPEpidermal growth factor receptor
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Authors
Xitong Dang, Xiaorong Zeng, Raul Coimbra, Brian P. Eliceiri, Andrew Baird,