REARRANGEMENT AND REGULATION OF IMMUNOGLOBULIN GENES

免疫球蛋白基因表达需要重链和轻链的重排， 在B细胞发育过程中， 元件进入增强子元件附近。 的重点 一项建议是继续研究控制IG基因重排的事件 以及在小鼠和人的B细胞个体发育早期的表达。 这 包括对调节生殖系转录的元件的表征 以及它们在靶向基因片段中的潜在作用， 重排 kappa内含子和3 '端的发育激活 增强子将通过转基因小鼠研究来检验。 的具体作用 内含子增强子的作用将通过检查 正常重排的A-MuLV转化细胞系中的增强子缺失 kappa基因和用于产生基因改变小鼠的ES细胞。 的 包含κ内含子的结构和功能组分 增强子将通过定义序列和蛋白质-DNA相互作用来研究 其有助于模型细胞中转录激活和抑制 文化体系。 这包括克隆一种新的诱导因子， 结合增强子中的一个区域，以及定义 所有序列基序的空间排列， 增强子活性 核心内含子增强子侧翼的序列， 作为增强子活性的沉默剂将被表征。 其中一些 研究将涉及小鼠和人类增强子的直接比较 组织和功能。 最后，一项正在进行的合作研究将 维持以研究T细胞依赖性、重链增强子介导的 抑制鼠杂交瘤中IgE表达。

Immunoglobulin gene expression requires rearrangement of heavy and light chain gene segments during B cell development, that brings promoter elements into the proximity of enhancer elements. The focus of this proposal is to continue to study events that control Ig gene rearrangement and expression early in B cell ontogeny, in both mouse and human. This includes characterization of elements which regulate germline transcription of the kappa locus, and their potential role in targeting gene segments for rearrangement. The developmental activation of the kappa intron and 3' enhancers will be examined by transgenic mouse studies. The specific role of the intron enhancer will be determined by examining the effects of enhancer deletion in A-MuLV transformed cell lines that normally rearrange kappa genes, and ES cells used to generate genetically altered mice. The structural and functional components that comprise the kappa intron enhancer will be studied by defining sequences and protein-DNA interactions that contribute to transcriptional activation and suppression in model cell culture systems. This includes cloning a novel, inducible factor that binds a region in the enhancer, as well as defining requirements for spatial arrangements of all the sequence motifs that contribute to full enhancer activity. Sequences that flank the core intron enhancer and act as silencers of enhancer activity will be characterized. A number of these studies will involve direct comparisons of mouse and human enhancer organization and function. Finally, an ongoing collaborative study will be maintained to study the T cell dependent, heavy chain enhancer-mediated suppression of IgE expression in murine hybridomas.