Gene expression of the POU factor Brn-3a is regulated by two different promoters.
Expression of the POU transcription factor Brn-3a is regulated spatially and temporally during embryogenesis and can be detected in a particular subset of neurons and neuronal tumors. In the present study, we investigated the transcriptional regulation of Brn-3a expression. The human promoter is TATA-less and contains two bona fide mRNA start sites spread over 500 nucleotides 5' of the ATG translation initiation codon. Furthermore, a second TATA-less promoter was detected in the first intron of the Brn-3a gene and our data suggest that this promoter regulates expression of the shorter isoform of the Brn-3a gene. Transcriptional activity from this promoter was found in neuronal cell lines but not in epithelial cells. The activity of this promoter was strongly enhanced upon deletion of a 24 base pair (bp) DNA element downstream of the transcription initiation sites. In addition, this DNA element was able to repress transcription from a heterologous promoter suggesting a function as a transcriptional silencer. The more distal upstream Brn-3a promoter directing the expression of the longer Brn-3a isoform is not affected by the presence of this putative 24 bp DNA element. We propose therefore that the existence of two promoters in the Brn-3a gene offers a possibility for the observed differential and cell type-specific expression of the gene.
Frass
Beate
B
Institut für Zellbiologie (Tumorforschung), I F Z, Universitätsklinikum Essen, Virchowstrasse 173, Essen, Germany.
Vassen
Lothar
L
Möröy
Tarik
T
D001483:Base Sequence; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics*; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D037941:Silencer Elements, Transcriptional; D050819:Transcription Factor Brn-3A; D014157:Transcription Factors / Q000235:genetics*; D024363:Transcription Initiation Site; D014162:Transfection
D004268:DNA-Binding Proteins; C494188:POU4F1 protein, human; D020033:Protein Isoforms; D012333:RNA, Messenger; D050819:Transcription Factor Brn-3A; D014157:Transcription Factors