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-binding proteins and has been linked to cell growth and proliferation through its regulation of mRNA stability. Here, we use an RNase protection assay to demonstrate that the mHuA transcript is relatively abundant in a range of mouse tissues, with the highest levels being found in lung and embryonic stem cells. We then cloned and mapped an 18 kb DNA fragment which encompasses the 5' end of the mHuA gene. The genomic organization in this region is similar to the neural-restricted family members, Hel-N1 (ELAVL2) and mHuD (Elavl4). The first exon is lengthy and untranslated, and the second exon, which includes the methionine start site, ends between the ribonucleoprotein motifs of the first RNA binding domain. Mapping of the mHuA transcript by primer extension demonstrated three potential transcription-initiation sites which were detected consistently among different tissues and cell lines. Analysis of the sequence flanking these sites revealed the presence of transcriptional elements including TATA, CREB, c-ets, and AP1 sites. Transfection analysis of this promoter region using a luciferase-reporter-gene assay indicated strong transcriptional activity both in HeLa and in mouse macrophage (RAW) cells which is consistent with the ubiquitous expression pattern of mHuA. Thus, while the genomic organization of mHuA is similar to the neural-restricted members of the Elav family, the promoter element differs substantially both by sequence analysis and transcriptional activity in non-neural cell types.