Analysis of the 5 ' end of the mouse Elavl1 (mHuA) gene reveals a transcriptional regulatory element and evidence for conserved genomic organization

mHuA (Elavl1) belongs to a highly conserved family of genes encoding RNA-bi nding proteins and has been linked to cell growth and proliferation through its regulation of mRNA stability. Here, we use an RNase protection assay t o demonstrate that the mHuA transcript is relatively abundant in a range of mouse tissues, with the highest levels being found in lung and embryonic s tem cells. We then cloned and mapped an 18 kb DNA fragment which encompasse s the 5' end of the mHuA gene. The genomic organization in this region is s imilar to the neural-restricted family members, Hel-N1 (ELAVL2) and mHuD (E lal4). The first exon is lengthy and untranslated, and the second exon, whi ch includes the methionine start site, ends between the ribonucleoprotein m otifs of the first RNA binding domain. Mapping of the mHuA transcript by pr imer extension demonstrated three potential transcription-initiation sites which were detected consistently among different tissues and cell lines. An alysis of the sequence flanking these sites revealed the presence of transc riptional elements including TATA, CREB, c-ets, and AP1 sites. Transfection analysis of this promoter region using a luciferase-reporter-gene assay in dicated strong transcriptional activity both in HeLa and in mouse macrophag e (RAW) cells which is consistent with the ubiquitous expression pattern of mHuA. Thus, while the genomic organization of mHuA is similar to the neura l-restricted members of the Elav family, the promoter element differs subst antially both by sequence analysis and transcriptional activity in non-neur al cell types. (C) 2000 Elsevier Science B.V. All rights reserved.