Regulation of PAX-6 gene transcription: alternate promoter usage in human brain

• Published in: Brain research. Molecular brain research. Vol. 60; no. 2; pp. 177 - 192
• Main Authors: Okladnova, Olga, Syagailo, Yana V., Mössner, Rainald, Riederer, Peter, Lesch, Klaus-Peter
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.1998; Elsevier
• Subjects: 3T3 Cells; Adult; Alternative promoter; Alternative Splicing; Animals; Base Sequence; Biological and medical sciences; Brain; Brain - metabolism; COS Cells; DNA-Binding Proteins - biosynthesis; DNA-Binding Proteins - genetics; Exons; Eye Proteins; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation; Gene transcription; Genomic Library; Homeodomain Proteins; Human; Humans; Mice; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Organ Specificity; Osteosarcoma; Paired box gene; Paired Box Transcription Factors; PAX-6; PAX6 Transcription Factor; Promoter Regions, Genetic; Recombinant Fusion Proteins - biosynthesis; Regulatory Sequences, Nucleic Acid; Repressor Proteins; Restriction Mapping; Sequence Alignment; Sequence Homology, Nucleic Acid; TATA Box; Transcription Factors - genetics; Transcription, Genetic; Transcription. Transcription factor. Splicing. Rna processing; Transfection; Tumor Cells, Cultured; Human; Brain; mRNA, messenger RNA; tRNA, transport RNA; cDNA, complementary DNA; 5′ RACE, rapid amplification of 5′ cDNA ends; Gene transcription; β-gal, β-galactosidase; PAX-6; Alternative promoter; 5′ UTR, 5′ untranslated region; RT-PCR, reverse transcription polymerase chain reaction; Paired box gene; Pax, paired box; Regulation(control); Gene; Transcription; Transcription promoter; Central nervous system; Regulatory sequence; Brain (vertebrata)
• ISSN: 0169-328X; 1872-6941
• DOI: 10.1016/S0169-328X(98)00167-3

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.