Immunity in Transgenic Mice

描述（由申请人提供）：类别转换DNA重组是 对于B细胞中的同种型转换很重要，并且似乎也参与了 一些癌基因的染色体易位然而，关于这些基因的染色体易位， 切换机制串联重复序列位于所有 H链抗体恒定区基因通常被认为是 在类别转换重组的靶向和/或机制中是重要的。 我们已经使用基因靶向技术从开关（S）中删除串联重复序列 小鼠中与C-mu恒定区相关的区域。令人惊讶的是，这些 突变小鼠仍然能够进行同种型转换，尽管效率 的过程被减少。我们还发现，切换到不同的同种型是 受S-mu串联重复序列缺失的差异影响。当前 应用程序试图扩展我们的初步结果，分析几个方面 DNA重组的过程首先，缺乏S-mu的小鼠将 分析以确定IgA转换是否如所示基本上完整 通过初步数据，并评估S-mu缺失对IgE转换的影响。 S-mu对开关的不同影响的潜在分子解释 将通过表征开关来研究对不同同种型的影响 同种型的重组连接位点显示最大和最小的 由于S-mu缺失的影响。第二，双链DNA断裂， 将在野生型和S-mu突变小鼠中分析JH-C mu内含子，以评估 DNA切割位点是否会受到S-mu缺失的影响。第三，基因 靶向将用于删除JH-C μ内含子内的额外序列 来定位同种型转换所需的序列。和 第四，通过基因打靶将特异性DNA序列引入IgH中， 在研究最小序列时转换有缺陷的等位基因 可以恢复切换能力。

DESCRIPTION (provided by applicant): Class switch DNA recombinations are important for isotype switching in B-cells and also appear to be involved in chromosomal translocations of some oncogenes However, little is known bout the switching mechanism. Tandemly-repeated sequences located upstream of all H-chain antibody constant region genes have generally been thought to be important in the targeting and/or the mechanism of class switch recombination. We have used gene targeting to delete the tandem repeats from the switch (S) region associated with the C-mu constant region in mice. Surprisingly, these mutant mice are still able to undergo isotype switching, though the efficiency of the process is reduced. We also find that switching to different isotypes is differentially affected by deletion of the S-mu tandem repeats. The current application seeks to extend our preliminary results to analyze several aspects of class switch DNA recombination. First, the mice lacking S-mu will be analyzed to determine whether IgA-switching is essentially intact as indicated by preliminary data and to assess the effect of S-mu deletion of IgE switching. Potential molecular explanations for the different effects of S-mu on switching to the different isotypes will be investigated by characterizing switch recombination junction sites for isotypes that show the greatest and least effect due to S-mu deletion. Second , double stranded DNA breaks within the JH-C mu intron will be analyzed in wild-type and S-mu mutant mice to assess whether DNA cleavage sites might be affected by S-mu deletion. Third, gene targeting will be used to delete additional sequences within the JH-C mu intron to localize those sequences that are required for isotype switching. And fourth, specific DNA sequences will be introduce by gene targeting into an IgH allele that is defective for switching to investigate the minimal sequences that can restore the capacity for switching.