GROWTH ARREST AND DNA DAMAGE INDUCIBLE GENE GADD153--REGULATION BY DNA DAMAGE

尽管所有细胞都对氧化应激和DNA损伤做出反应， 大量基因的诱导，人们对其背后的原因知之甚少 在真核生物中参与这些反应的机制。GADD153是一个 CCAAT/增强子结合蛋白(C/EBP)相关基因 对包括DNA在内的各种应激反应高度诱导 损伤和氧化应激，并提供了一个有用的模型 引起庆大霉素反应的分子机制 压力。它可能是其他C/EBP的负调控因子 转录激活子，因此可能在 确定哪些其他基因表达或抑制作为对 这些压力。我们最近的研究集中在这些途径上。 介导GADD153对DNA损伤的诱导和 氧化应激。与其他基因转录激活相反 DNA损伤诱导基因，GADD153诱导似乎涉及 既不是蛋白激酶C也不是酪氨酸激酶，而是需要一个 未知的丝氨酸-苏氨酸激酶，因此代表着一种独特的 细胞对庆大霉素应激反应的途径。此外, 根据它们对细胞内谷胱甘肽水平的相对敏感性， 似乎氧化应激和dna损伤调节转录。 通过不同的途径。使用凝胶迁移率变化分析，我们有 鉴定GADD153启动子区域的几个顺式元件 显示了与核裂解物中存在的因子的增强结合 用DNA损伤剂处理过的细胞制备的。这些是 可能代表重要的转录因子的结合 介导基因的转录激活以响应 压力。 探讨DNA损伤和/或修复能力之间的关系 和GADD153的表达我们检测了GADD153的激活情况 顺铂耐药与顺铂耐药HeLa细胞启动子的比较 在他们接受基因毒剂治疗后。我们观察到更低的 GADD153在耐药细胞中的表达 它们所源自的细胞。这些发现支持这样的观点 GADD153的表达与细胞对 DNA损伤剂的细胞毒性作用。

Although all cells respond to oxidative stress and DNA damage with the induction of numerous genes, little is known about the underlying mechanisms involved in these responses in eucaryotes. GADD153 is a CCAAT/enhancer-binding protein (C/EBP)-related gene that is rapidly and highly induced in response to a variety of stresses including DNA damage and oxidative stress and provides a useful model for examining the molecular mechanisms involved in eliciting the response to gentoxic stress. It is a putative negative regulator of other C/EBP transcriptional activators, and as such could play a key role in determining what other genes are expressed or repressed in response to these stresses. Our recent studies have concentrated on the pathways mediating the induction of GADD153 in response to DNA damage and oxidative stress. In contrast to transcriptional activation of other DNA damage inducible genes, GADD153 induction appears to involve neither protein kinase C nor tyrosine kinases, but rather requires an unidentified serine-threonine kinase, thus representing a unique pathway in the cellular response to gentoxic stress. In addition, based on their relative sensitivity to cellular levels of glutathione, it appears that oxidative stress and DNA damage regulate transcription through different pathways. Using gel mobility shift assays we have identified several cis elements in the promoter region of the GADD153 which show enhanced binding to factors present in nuclear lysates prepared from cells treated with DNA damaging agents. These are likely to represent binding of transcription factors important in mediating the gene's transcriptional activation in response to the stress. To explore the relationship between DNA damage and/or repair capacity and the expression of GADD153 we examined the activation of the GADD153 promoter in cisplatin-resistant versus cisplatin resistant HeLa cells following their treatment with the genotoxic agent. We observed lower GADD153 expression in the resistant cells relative to the sensitive cells from which they were derived. These findings support the notion that the expression of GADD153 is related to the cell's sensitivity to cytotoxic effects of the DNA damaging agent.