REGULATION OF IGH MU LOCUS CLASS SWITCH RECOMBINATION

IGH MU 位点类别开关重组的调控

• 批准号: 6260412
• 负责人: Andrea Bottaro
• 金额: $ 34.94万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-02-01 至 2006-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6260412
• 关键词: B lymphocyte; antibody formation; gene rearrangement; genetic regulation; genetic regulatory element; genetically modified animals; immunoglobulin M; immunoglobulin genes; laboratory mouse; site directed mutagenesis; transcription factor

DESCRIPTION (investigator's abstract): During a humoral immune response, immunoglobulin (Ig) class switching changes the effector function of an antibody, without altering its specificity for antigen, by replacing the heavy chain constant region (CH) sequences of the u gene with those of a gamma, epsilon or alpha gene. This is accomplished via recombination of DNA sequences (S regions) 5' of Cu and of the "downstream" CH genes. According to the current model, regulation of class switch recombination (CSR) in response to specific B cell stimuli is achieved by modulation of the transcriptional activity of the target CH genes to generate so-called "germline" (or "switch") transcripts. The u locus plays a particularly important role in class switching, since Su is the obligate donor of every CSR event. Yet, the present models of CSR regulation do not satisfactorily explain all the features of u CSR activity, since the u locus switch transcripts are expressed throughout B cell development in the absence of detectable CSR activity. Moreover, deletions of the known regulatory and structural elements of the u switch transcripts have only a partial effect on u CSR. In a series of experiments stemming from these observations, we have recently identified novel u locus transcription units that may be involved in CSR regulation. Taking advantage of this new information, we propose here a series of experiments aimed at elucidating the regulatory mechanisms that affect CSR at the u locus. Specifically, we will characterize the elements that regulate expression of the new transcripts, and assess their function by targeted mutagenesis. To test whether generation and splicing of u switch transcripts is essential for CSR, as recently suggested for other CH genes, we are going to replace the entire u switch transcript region with exogenous DNA sequences. In transgenic experiments, we will assay for the role of cis- and trans-acting regulatory mechanisms in controlling Su recombination. Finally, by replacing the endogenous Su with different types of sequences (repetitive and non-repetitive, S-related or not) we will establish the molecular requirements for the Su region sequences as efficient CSR substrates.

描述（研究者摘要）：在体液免疫反应期间， 免疫球蛋白 (Ig) 类别转换改变了免疫球蛋白的效应功能 抗体，通过替换重链而不改变其对抗原的特异性 u基因的链恒定区（CH）序列与γ基因的链恒定区（CH）序列， epsilon 或 alpha 基因。这是通过 DNA 序列重组来完成的 （S 区）Cu 和“下游”CH 基因的 5'。根据目前的 模型，响应特定 B 的类别转换重组 (CSR) 调节 细胞刺激是通过调节转录活性来实现的 靶向 CH 基因以生成所谓的“种系”（或“转换”）转录本。 u 基因座在类别转换中起着特别重要的作用，因为 Su 是 每个企业社会责任活动的义务捐助者。然而，目前的企业社会责任模式 监管并不能令人满意地解释企业社会责任活动的所有特征， 因为 u 位点开关转录本在整个 B 细胞中表达 在缺乏可检测的企业社会责任活动的情况下发展。此外，删除 u 开关转录物的已知调控和结构元件具有 对企业社会责任仅产生部分影响。在一系列的实验中 观察，我们最近发现了新的 u 位点转录单位 可能涉及企业社会责任监管。利用这个新的优势 信息，我们在这里提出一系列实验，旨在阐明 影响 u 位点 CSR 的监管机制。具体来说，我们将 描述调节新转录本表达的元件，以及 通过定向诱变评估其功能。测试是否生成和 正如最近所建议的，u switch 转录本的剪接对于 CSR 至关重要 对于其他 CH 基因，我们将替换整个 u switch 转录本 具有外源DNA序列的区域。在转基因实验中，我们将检测 顺式和反式调节机制在控制 Su 中的作用 重组。最后，通过用不同类型的Su替换内源性Su 我们将建立序列（重复和非重复、S 相关或不相关） Su 区序列作为有效 CSR 的分子要求 基材。