Identification of a p53-dependent negative response element in the bcl-2 gene.
Identification of a p53-dependent negative response element in the bcl-2 gene.
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发表时间：
1994-06
期刊：
影响因子：
11.2
通讯作者：
T. Miyashita;M. Harigai;M. Hanada;John Calvin Reed
中科院分区：
文献类型：
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作者：
T. Miyashita;M. Harigai;M. Hanada;John Calvin Reed
最近，我们发现P53抑癌基因产物可以抑制bcl2基因的表达。在这份报告中，我们利用p53表达载体和含有bcl2基因区域的氯霉素乙酰转移酶(CAT)报告基因构建的共转染方法，探讨了p53介导bcl2基因表达下调的分子基础。将报告基因导入p53缺陷型人肺癌细胞系H358后，只含有bc1-2启动子区域和上游序列的报告基因构建体不被p53抑制。然而，在bcl2/cat构建物中包含与5‘非翻译区对应的bcl2基因序列，导致p53依赖的下调。BCL-2基因5‘非翻译区的195个碱基对的片段能够在SV40即刻早期区启动子的控制下，对含有CAT的异源表达载体进行p53依赖的抑制。当放置在SV40-CAT转录单元的上游或下游时，这个P53阴性反应元件以一种与方向无关的方式发挥作用。这些结果表明，bcl2基因中存在一个负反应元件，p53可能通过它直接或间接转录下调该基因的表达，该基因参与了细胞程序性死亡的调节。
Recently, we have shown that the p53 tumor suppressor gene product can inhibit expression of the bcl-2 gene. In this report, we explored the molecular basis for p53-mediated down-regulation of bcl-2 gene expression using a cotransfection approach involving p53 expression plasmids and chloramphenicol acetyltransferase (CAT) reporter gene constructs containing regions from the bcl-2 gene. When transfected into a p53-deficient human lung cancer cell line H358, reporter gene constructs containing only the promoter region of bcl-2 and upstream sequences were not suppressed by p53. Inclusion of bcl-2 gene sequences corresponding to the 5' untranslated region in bcl-2/CAT constructs, however, resulted in p53-dependent down-regulation. A 195-base pair segment from the bcl-2 gene 5' untranslated region was found to be capable of conferring p53-dependent repression on a heterologous expression plasmid containing CAT under the control of an SV40 immediate early-region promoter. This p53-negative response element functioned in an orientation-independent manner when placed either upstream or downstream of the SV40-CAT transcription unit. The results demonstrate the existence of a negative response element in the bcl-2 gene through which p53 may either directly or indirectly transcriptionally down-regulate expression of this gene involved in the regulation of programmed cell death.