| Research Abstract |
PEBP2alpha subunit is a member of a novel transcription factor family with the Runt-Domain which is responsible for its DNA binding and hetrodimerizing with beta subunit activities. Three murine PEBP2alpha genes, alphaA, alphaB and alphaC, have been identified. alphaA is originally isolated as a Polyoma virus enhancer binding protein and involved the T cell specific gene expression or early development. alphaB is the murine homologue of human AML1 which was found at the breakpoint of the t(8,21). The only gene encoding beta subunit was identified and the expression of its mRNA is ubiquitous among the cell lines we tested. The expressions of alphaA mRNAs indicate the cell type specific manner and suggest to vary its function as a transcription factor. In this study, we analyzed the expression pattern of alphaA subspecies (alphaA1 , alphaA2, alphaA3) mRNAs to characterize the machinery of cell type specificity of mRNA expression. A primary Northern blot analysis suggested that alphaA3 mRNA was minor species like alphaA2 mRNA.To confirm their expression, RT-PCR was performed and was found that the alphaA3 mRNA, like alphaA1, was expressed both in Ha-ras transformed NIH3T3 cells and murine T cell line, EL4. Moreover, little expression of alphaA3, like alphaA1, was detected in murine embryonic carcinoma cell line, P19. After the treatment of retinoic acid, however, significant induction of alphaA3 mRNA was obsered in the P19 cells. On the other hand, alphaA2 mRNA was expressed in all cell lines we tested as well as beta subunit mRNAs. These study strongly suggested that the various isoforms derived from a single gene by alternative splicing were differently regulated the expression of each mRNA.It is a valuable question we should discuss further that the biological significance of this expression specificity and the mechanism of their transcription regulation.
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