| Research Abstract |
Out of known 5 isoforms of PP2Cbeta, 3 isoforms, beta-3, -4 and -5, are distinctively expressed in testis and intestine. There has been reports on the variation of 5' end of the PP2Cbeta cDNAs, assigned as type A and B.Also, a promoter (P1), which enables ubiquitous expression to the gene, was recently brought to light at 5' of type A region. In order to investigate the possible variations of the 5' end of the PP2Cbeta mRNAs, 5'-RACE and cloning of the gene of that region were performed, and 3 exons were identified : type A as exon1, type B as exon 3 and exon 2 as a novel one. RT-PCR and Southern blotting analysis showed the exon 2 is expressed only in testis, intestine and liver. Based on these results, 5' region of the exon 2 was further investigated as a potential organ-specific promoter (P2). Multiple transcription start sites were observed by the primer extention experiment, and several SRY and NRE of c-mos consensus sequences were observed, implying the possible involvement of the P2 in sexual differentiation and testicular function. Luciferase reporter assay with P19 EC cells proved significant promoter activity of P2.
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