Dani C, Blanchard J M, Piechaczyk M, El Sabouty S, Marty L, Jeanteur P
Proc Natl Acad Sci U S A. 1984 Nov;81(22):7046-50. doi: 10.1073/pnas.81.22.7046.
To address the possibility that the expression of the myc gene might be regulated at a post-transcriptional level, we have investigated the half-life of myc mRNA in various cells. Our survey included normal human embryonic fibroblasts as well as transformed human cells of various origins: cervix carcinoma (HeLa), breast carcinoma (MCF7), Burkitt lymphoma (Daudi), and promyelocytic leukemia (HL60). All these cells revealed an extreme instability of myc mRNA (half-life, approximately equal to 10 min), suggesting that the control of myc mRNA degradation might be a general means (although not necessarily exclusive) of regulating both the level and the timing of myc gene expression. Inhibition of protein synthesis resulted in a dramatic stabilization of myc mRNA in HeLa, MCF7, and HL60 cells, suggesting that the controlling element might itself be, at least in these cells, a protein of rapid turnover. This finding opens the way to studying the mechanism of myc mRNA inactivation in these different cell types. However, protein synthesis inhibition had no effect on myc mRNA instability in other transformed (Daudi) cell lines as well as normal embryonic human fibroblasts. These different types of behavior suggest that the post-transcriptional control of myc gene expression might involve multiple factors that would be differently affected in various cell types.
为了探究myc基因的表达是否可能在转录后水平受到调控，我们研究了myc mRNA在各种细胞中的半衰期。我们的研究对象包括正常人胚胎成纤维细胞以及多种来源的转化人细胞：子宫颈癌（HeLa）、乳腺癌（MCF7）、伯基特淋巴瘤（Daudi）和早幼粒细胞白血病（HL60）。所有这些细胞中的myc mRNA都表现出极度不稳定性（半衰期约为10分钟），这表明控制myc mRNA降解可能是调节myc基因表达水平和时间的一种普遍方式（尽管不一定是唯一方式）。在HeLa、MCF7和HL60细胞中，蛋白质合成抑制导致myc mRNA显著稳定，这表明调控元件本身，至少在这些细胞中，可能是一种快速周转的蛋白质。这一发现为研究这些不同细胞类型中myc mRNA失活的机制开辟了道路。然而，蛋白质合成抑制对其他转化细胞系（Daudi）以及正常人胚胎成纤维细胞中的myc mRNA不稳定性没有影响。这些不同类型的行为表明，myc基因表达的转录后调控可能涉及多种因素，这些因素在不同细胞类型中受到的影响各不相同。
