Activation and Inactivation of Immunoglubulin VH Genes

描述（由申请方提供）：免疫球蛋白重链的组装 (IgH)在B细胞分化过程中的基因需要两个重组事件。 首先，几个DH基因片段之一重排为JH基因片段， DJH加入。第二，数百个VH基因片段中的一个重排为DJH， 连接以产生V（D）J重组等位基因。一小部分V（D）J 重组等位基因将编码IgH蛋白。那些制造IgH蛋白的细胞 将终止IgH基因的重组，这一过程被称为等位基因重组。 排斥。早期的研究表明，等位基因排斥作用的步骤， VH到DJH的重组。VH重组停止的机制 不知道。 在最近对IgH基因座的染色质结构的研究中，我们发现VH 基因由三种不同的机制激活。最大的VH J558基因 位于该基因座5 ′端的IL-7家族被IL-7激活。3'最 由VH 8 1X和VHSM 7表示的VHS仅在含有以下物质的细胞中被激活： DJH重组等位基因。位于VHJ 558和VHSM 7之间的基因，由 VH 10在V-abl转化的细胞中被激活，表明它们可能是 由酪氨酸激酶激活。 在本申请中，我们提出严格建立激活 中间体和3？VH基因（Aim 1）。然后，我们建议测试模型 等位基因排斥是终止激活VH的信号的结果， 基因（Aim 2）。这将通过体外和 在遗传改变的小鼠品系中的体内分析。 这些研究不仅对全面了解IgH具有重要意义， 基因组装，也是为了深入了解更普遍的问题， 基因组的大片段被激活。

DESCRIPTION (provided by the applicant): Assembly of immunoglobulin heavy chain (IgH) genes during B cell differentiation requires two recombination events. First, one of several DH gene segments rearrange to JH gene segments to produce DJH joins. Second, one of several hundred VH gene segments rearrange to the DJH join to produce V(D)J recombined alleles. A small proportion of V(D)J recombined alleles will encode IgH protein. Those cells that make IgH protein will terminate recombination of the IgH gene, a process referred to as allelic exclusion. Earlier studies indicate that allelic exclusion operates at the step of VH to DJH recombination. The mechanism by which VH recombination is stopped is not known. In recent studies of the chromatin structure of the IgH locus we found that VH genes are activated by three distinct mechanisms. The largest VH J558 gene family, that is at the 5' end of the locus, is activated by IL-7. The 3' -most VHS, represented by VH8 1X and VHSM7, are activated only in cells that contain DJH recombined alleles. Genes that lie between VHJ558 and VHSM7, represented by VH10, are activated in V-abl transformed cells suggesting that they may be activated by tyrosine kinases. In this application we propose to rigorously establish mechanisms that activate the intermediate and 3?-VH genes (Aim 1). We then propose to test the model that allelic exclusion is a consequence of terminating signals that activate VH genes (Aim 2). This will be accomplished by a combination of in-vitro and in-vivo analyses in genetically altered mouse strains. These studies are important not only for a comprehensive understanding of IgH gene assembly, but also for insights into the more general question of how large segments of the genome are activated.