FUNCTIONS OF ANTIBODY SWITCH REGIONS

申请者描述：班级切换DNA重组对 B细胞中的同型转换，似乎也与染色体有关 一些癌基因易位。然而，人们对这种转换知之甚少 机制。位于所有H链抗体上游的Tandemly重复序列 恒定区基因通常被认为在 定向和/或类切换重组的机制。我们已经使用了基因 目标是从相关的开关(S)区域中删除串联重复序列 与小鼠体内的铜恒定区。令人惊讶的是，这些突变的小鼠仍然 能够进行同型转换，尽管该过程的效率是 适度降价。我们的发现表明，SU。串联重复不是 切换过程所需的。目前的建议旨在延长我们的 分析班级转换DNA的几个方面的初步结果 重组。据报道，DNA错配修复(MMR)酶还 影响转班效率和接班地点选择。我们希望 研究SU串联重复序列与MMR的相互关系 在转换过程中的酶通过产生双突变动物而缺乏 SU重复和特定的单个MMR蛋白。第二，我们想要 确定在缺乏的ASU JH-Cu内含子中是否能形成RNA：DNA复合体 串联重复序列元件，以探索先前提出的 这些复合体在转换过程中。最后，对亲属进行调查 与已发现的串联重复序列相比，SU串联重复序列的重要性 与下游的CH基因相关联，我们将通过基因打靶产生突变 缺乏Sa或同时缺乏Sa和Sa的小鼠。对这些系统中的交换进行分析 突变的小鼠应该表明S下游的区域是否更多 在控制重组过程中很重要，正如已经由 人工开关基板的一些研究。

APPLICANT'S DESCRIPTION: 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 about the switching mechanism. Tandemly-repeated sequences located upstream of all H-chain antibody constant regions 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 Cu constant region in mice. Surprisingly, these mutant mice are still able to undergo isotype switching, although the efficiency of the process is modestly reduced. Our findings indicate that the Su. tandem repeats are not required for the switching process. The current proposal seeks to extend our preliminary results to analyze several aspects of class switch DNA recombination. It has been reported that DNA mismatch repair (MMR) enzymes also affect the efficiency and joining site selection of class switching. We wish to investigate the mutual relationships between the Su tandem repeats and MMR enzymes in the switching process by producing double-mutant animals that lack both the Su repeats and specific individual MMR proteins. Second, we want to determine whether RNA:DNA complexes can form in the ASu JH-Cu intron that lacks the tandem repeat element to explore the previously suggested importance of these complexes in the switching process. Finally, to investigate the relative importance of the Su tandem repeats, in comparison to the tandem repeats found associated with downstream CH genes, we will produce, by gene targeting, mutant mice that lack either Sa or both Su and Sa. Analysis of switching in these mutant mice should indicate whether downstream S regions are much more important in controlling the recombination process as has been suggested by some studies of artificial switch substrates.