FUNCTIONS OF ANTIBODY SWITCH REGIONS

申请人的描述：类别转换DNA重组对于 B细胞中的同种型转换，并且似乎也参与染色体 一些致癌基因的易位。然而，人们对这种转换知之甚少 机制位于所有H链抗体上游的串联重复序列 恒定区基因通常被认为是重要的， 靶向和/或类别转换重组的机制。我们用基因 靶向以从相关的开关（S）区域删除串联重复序列， 与小鼠的铜恒定区的关系。令人惊讶的是，这些突变小鼠仍然 能够经历同种型转换，尽管该过程的效率是 适度减少。我们的研究结果表明，苏。串联重复序列不是 切换过程所需的。目前的建议旨在扩大我们的 分析类转换DNA的几个方面的初步结果 重组据报道，DNA错配修复（MMR）酶也 影响了类切换的效率和加入站点的选择。我们希望 探讨Su串联重复序列与MMR的相互关系 通过生产缺乏双突变体的动物， Su重复序列和特定的单个MMR蛋白。第二，我们要 确定RNA：DNA复合物是否可以在缺乏的ASu JH-Cu内含子中形成 串联重复元件，以探索先前提出的重要性， 这些复合物在切换过程中。最后，调查相对 与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CH基因相关，我们将通过基因打靶， 缺乏Sa或Su和Sa两者的小鼠。分析开关在这些 突变小鼠应该指出下游S区是否比 重要的是控制重组过程，如已经提出的， 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.