Regulation of alternative SRC promoter usage in HepG2 hepatocellular carcinoma cells
Regulation of alternative SRC promoter usage in HepG2 hepatocellular carcinoma cells
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DOI：
10.1016/j.gene.2004.04.021
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发表时间：
2004-08-04
期刊：
影响因子：
3.5
通讯作者：
Bonham, K
中科院分区：
文献类型：
--
作者：
Dehm, SM;Bonham, K
替代启动子允许单个基因表达模式的空间和时间多样性增加。人SRC基因编码非受体c-Src酪氨酸激酶，由两个间隔约1 kb的交替启动子调控。远端SRC 1 α启动子是组织限制性的，而近端SRC 1A启动子的表达似乎是普遍存在的。阐明SRC转录调控机制的障碍是发现SRC启动子单独的强度与体内使用的相对强度不匹配。例如，在HepG 2肝细胞癌细胞中，SRC 1A在分离时比SRC 1 α显著更强，尽管SRC 1 α是该细胞系中使用的主要启动子。以前，我们已经表明，HepG 2细胞，以及各种结肠癌细胞系，显示激活SRC转录，这是与升高的c-Src表达和活性所必需的这些细胞的生长和生存。因此，这些发现强调了理解SRC转录调控机制在人类癌症中的重要性。我们假设个体SRC启动子强度和体内相对使用之间的差异源于缺乏连接的启动子上下文。因此，我们已经开发并验证了一种新的双SRC启动子报告策略，以允许在其自然连接的背景下同时研究两个SRC启动子的机制。这种方法已经产生了证据表明SRC激活通过HepG 2细胞中启动子区域外的基因组元件进行。因此，我们进行了初步的研究DNasel超敏（DH）的SRC基因座内的网站组成。这种方法确定了一个HepG 2特异性DH位点，该位点显示了对SRC 1 α启动子的激活潜力。因此，这些结果提供了重要的洞察肝癌细胞中SRC转录激活的机制。(C)2004 Elsevier B. V.保留所有权利。
Alternative promoters allow for increased spatial and temporal diversity in expression patterns for a single gene. The human SRC gene, encoding the non-receptor c-Src tyrosine kinase, is regulated by two alternative promoters separated by approximately I kb. The distal SRC1alpha promoter is tissue-restricted, while expression of the proximal SRC1A promoter appears to be ubiquitous. A barrier to elucidating the mechanisms of SRC transcriptional regulation has been the finding that the individual strengths of the SRC promoters in isolation do not match their relative strength of use seen in vivo. For example, in HepG2 hepatocellular carcinoma cells, SRC1A is significantly stronger in isolation than SRClalpha, despite SRC1alpha being the predominant promoter used in this cell line. Previously, we have shown that HepG2 cells, as well as various colon cancer cell lines, display activated SRC transcription, which is linked to the elevated c-Src expression and activity necessary for growth and survival of these cells. These findings thus highlight the importance of understanding the mechanisms of SRC transcriptional regulation in human cancer. We hypothesize the discrepancy between individual SRC promoter strength and relative usage in vivo stems from a lack of linked promoter context. Therefore, we have developed and validated a novel dual SRC promoter reporter strategy to allow the simultaneous mechanistic study of both SRC promoters in their natural linked context. This approach has yielded evidence that SRC activation proceeds through genomic element(s) outside the promoter region in HepG2 cells. Therefore, we performed a preliminary study of DNasel hypersensitive (DH) site composition within the SRC locus. This approach identified a HepG2-specific DH site that displayed activating potential towards the SRC1alpha promoter. These results thus provide important insight to the mechanism of SRC transcriptional activation in liver cancer cells. (C) 2004 Elsevier B.V. All rights reserved.