CCAAT/enhancer binding protein α （C/EBPα） is a transcriptional regulatory factor that inhibits cell proliferation, and alternative translational initiation produces two polypeptides, C/EBPαp30 and C/EBPαp42. By ...CCAAT/enhancer binding protein α （C/EBPα） is a transcriptional regulatory factor that inhibits cell proliferation, and alternative translational initiation produces two polypeptides, C/EBPαp30 and C/EBPαp42. By expression profiling, it was revealed that C/EBPap30 specifically inhibited a unique set of genes, including MPP 11, p84N5 and SMYD2, which were not affected by C/EBPαp42 in both QSG-7701 hepatocyte cell line and QGY-7703 hepatoma cells. Semiquantitative RT-PCR analysis independently confirmed these results. Chromatin immunoprecipitation assay showed that C/EBPαp30 bound to the promoters of these genes more strongly than C/EBPαp42. In clinical hepatoma samples in which C/EBPα was downregulated, all three genes specifically inhibited by C/EBPαp30 were upregulated. However, repression of MPP 11, p84N5 and SMYD2 genes might not be directly involved in C/EBPαp30-mediated growth inhibition. Our data suggest that C/EBPαp30 regulates a unique set of target genes and is more than a dominant-negative regulator of C/EBPαp42.展开更多
文摘CCAAT/enhancer binding protein α （C/EBPα） is a transcriptional regulatory factor that inhibits cell proliferation, and alternative translational initiation produces two polypeptides, C/EBPαp30 and C/EBPαp42. By expression profiling, it was revealed that C/EBPap30 specifically inhibited a unique set of genes, including MPP 11, p84N5 and SMYD2, which were not affected by C/EBPαp42 in both QSG-7701 hepatocyte cell line and QGY-7703 hepatoma cells. Semiquantitative RT-PCR analysis independently confirmed these results. Chromatin immunoprecipitation assay showed that C/EBPαp30 bound to the promoters of these genes more strongly than C/EBPαp42. In clinical hepatoma samples in which C/EBPα was downregulated, all three genes specifically inhibited by C/EBPαp30 were upregulated. However, repression of MPP 11, p84N5 and SMYD2 genes might not be directly involved in C/EBPαp30-mediated growth inhibition. Our data suggest that C/EBPαp30 regulates a unique set of target genes and is more than a dominant-negative regulator of C/EBPαp42.
