MOLECULAR BIOLOGY OF CELLULAR INJURY

在细菌和酵母中，许多在细胞反应中起重要作用的基因 DNA损伤是由这种损伤引起的。直到最近，证据表明， 哺乳动物细胞对遗传毒性应激的特异性反应不是 决定性的在过去的一年里，我们集团一直处于前列， 证明哺乳动物细胞中的某些基因可以特异性地 诱导的特定类型的DNA损伤和SOS样反应存在 在哺乳动物细胞中。我们开发了一种杂交减法技术， 分离编码DNA损伤诱导型（DDI）转录物的cDNA克隆，和 已经分离了20多种不同的新DDI基因的cDNA克隆。最 仅由DNA损伤引起，而不是其他类型的压力，如热， 冲击.我们已经对这些cDNA克隆中的大多数进行了测序， 这些序列中的一些的分离的基因组克隆。一个cDNA克隆，DDIA 18 被发现编码一种mRNA，该mRNA仅由DNA损伤剂诱导， 核苷酸切除（UV型）修复，并被发现编码一个 单链DNA结合蛋白。人和啮齿动物的cDNA克隆 DDIA 18 mRNA已经测序;预测的肽序列已经测序。 非常保守，这意味着这种蛋白质在 细胞作用。我们的其他几个DDI基因被发现是协调的 由DNA损伤或细胞生长抑制引起。有好 在细菌和真核生物中都有证据表明， 在DNA损伤后可以具有保护作用;例如，一个SOS基因 是一种生长停滞基因。与D合作。尼伯特，我们找到了 这些基因在突变小鼠中协同过表达， 可能会让我们深入了解他们的监管。其中两个基因 已测序和新描述的调控区已被初步 鉴定;已经开发了针对其中一种蛋白质的抗体。在 与I合作。Hickson和L.巴罗，我们DDI的表达 DNA修复突变体中的转录本进行了研究。几个例子 在突变体中表达转录的增加和减少 细胞被观察到。我们的大多数DDI序列的功能是 未知的，但它是可能的，至少有一些蛋白质产品的 这些转录物在细胞对DNA损伤的反应中起作用。

In bacteria and yeast, many of the genes important in the cellular response to DNA damage are induced by such damage. Until recently, evidence for such specific responses to genotoxic stress in mammalian cells was not definitive. In the last year, our group has been in the forefront in demonstrating that certain genes in mammalian cells can be specifically induced by specific types of DNA damage and that SOS-like responses exist in mammalian cells. We developed a hybridization subtraction technique to isolate cDNA clones coding for DNA-damage-inducible (DDI) transcripts, and have isolated cDNA clones for more than 20 different new DDI genes. Most were only induced by DNA damage and not other types of stress such as heat shock. We have sequenced most of these cDNA clones and recently have isolated genomic clones for some of these sequences. One cDNA clone, DDIA18 was found to encode an mRNA only induced by DNA-damaging agents repaired by nucleotide excision (UV-type) repair, and was found to code for a single-stranded-DNA binding protein. cDNA clones for both human and rodent DDIA18 mRNA have been sequenced; the predicted peptide sequence has been very highly conserved which implies that this protein plays an important cellular role. Several other of our DDI genes were found to be coordinately induced by either DNA damage or inhibition of cell growth. There is good evidence in both bacteria and eukaryotes that inhibition of cell growth after DNA damage can have a protective effect; e.g., one of the SOS genes is a growth arrest gene. In collaboration with D. Nebert, we have found that these genes were coordinately overexpressed in a mouse mutant which may provide insight into their regulation. Two of these genes have been sequenced and newly described regulatory regions have been tentatively identified; antibodies to one of the proteins have been developed. In collaboration with I. Hickson and L. Barrows, expression of our DDI transcripts in DNA repair mutants has been investigated. Several examples of both increased and decreased expression transcription in the mutant cells has been observed. The functions of most of our DDI sequences are unknown, but it is probable that the protein products of at least some of these transcripts play a role in the cellular response to DNA damage.