Regulation of PAX-6 gene transcription: alternate promoter usage in human brain.
We have isolated and characterized the 5'-flanking regulatory region of the human PAX-6 gene. Mapping of transcription initiation sites revealed the existence of an additional non-coding 5' exon, exon 1A. Functional analyses indicated that PAX-6 transcription is regulated by two distinct promoters, A and B, resulting in alternative transcription of exon 1A or 1B and joint transcription of exons 2 to 13. While a single initiation site was identified for exon 1A, transcription of exon 1B appears to be initiated from more than one site downstream of the promoter B-associated TATA motif. Multiple potential binding sites for transcription factors were found in the regions of promoter A and B. Although a 1.1-kb fragment of promoter A and a 1.5 kb fragment of promoter B, which had been fused to a reporter gene and transiently expressed in cell lines, displayed constitutive promoter activity, transcription of PAX-6 driven by promoter B was considerably higher than by promoter A in various regions of human postmortem brain. Transcript PAX-6B was primarily expressed in cerebellar cortex, whereas relatively low concentrations were detected in other brain areas. Functional dissection by serial deletions revealed several clusters of both activating elements and cell-selective silencers within the regulatory regions upstream of exon 1A and 1B. Coexpression of the promoter B constructs with a vector expressing PAX-6 modulated promoter B activity, thus indicating autoregulation by PAX-6 transcription. In conclusion, our findings suggest that PAX-6 transcription is regulated by alternate usage of promoter A and B, and that in adult human brain expression of PAX-6 is primarily controlled by promoter B. Alternate promoter usage and differential PAX-6 transcription are likely to play a critical role in brain development and neuroplasticity.
Department of Psychiatry, University of Wuerzburg, Fuechsleinstr. 15, 97080, Wuerzburg, Germany.
O
O
Okladnova
Y V
YV
Syagailo
R
R
Mössner
P
P
Riederer
K P
KP
Lesch
D016475:3T3 Cells; D000328:Adult; D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism*; D019556:COS Cells; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D005091:Exons; D005136:Eye Proteins; D005786:Gene Expression Regulation; D015698:Genomic Library; D018398:Homeodomain Proteins; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009928:Organ Specificity; D012516:Osteosarcoma; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins; D015183:Restriction Mapping; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D016385:TATA Box; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; C000605730:PAX6 protein, human; D051761:Paired Box Transcription Factors; C000605732:Pax6 protein, mouse; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors