Co-ordination of recombination and allelic exclusion at IgH and Igk loci

描述(由申请人提供)：在发育中的B淋巴细胞的复杂染色质环境中，如何维持忠实的DNA重排的分子细节是我实验室正在进行的研究的重点。我们有新的数据表明，IgH基因受Ig基因座调控，并已确定了两个Ig基因调控元件，3‘E？增强子和Sis(沉默因子)参与了相互作用的序列。当重组酶的靶点从IgH位点转移到Ig？时，通过在前B细胞向前B细胞转变时两个基因座的瞬时关联来实现调节。轨迹。我们的目的是阐明两个基因座之间关联的功能意义，并从分子细节上了解关联是如何实现的。我们的假设是，免疫球蛋白和免疫球蛋白基因座的关联在加强免疫球蛋白基因座的等位基因排除中起着核心作用，这对于维持重组过程的完整性和确保基因组的稳定至关重要。由于重组和等位基因排斥的解调可导致免疫缺陷、自身免疫和涉及Ig基因座的易位，因此了解其潜在的机制是非常必要的。此外，这些研究对整个基因调控具有重要意义。公共卫生相关声明：免疫球蛋白(Ig)基因的有序重排是适应性免疫所必需的一个高度调控的过程，通过等位基因排除来协调B和T淋巴细胞受体的表达，确保克隆，同时保护基因组免受这些固有的不稳定重组事件的影响。在发育中的B淋巴细胞复杂的染色质环境中，如何维持忠实的DNA重排的分子细节是我实验室正在进行的研究的重点。我们最近的研究表明，着丝粒周长Ig？等位基因将未重排的IgH等位基因导向一个共享的着丝粒周围簇。在这种抑制环境中，这两个基因座的关联随后会导致非功能等位基因上的IgH基因座去牵连。这确定了一种协调可获得性和表达方式变化的新机制。需要检验的假设是IgH和Ig之间的联系？基因座在执行等位基因排斥中起着核心作用，这对于维持重组过程的完整性和确保基因组的稳定性至关重要。这笔赠款的目的是为了从分子上详细了解免疫球蛋白基因座关联有助于等位基因排除和基因组稳定的机制。了解这两个基因座的变化是如何协调的，并确定涉及的途径在该领域是至关重要的，因为重组和等位基因排斥的去调节可导致涉及Ig基因座的免疫缺陷、自身免疫和易位。这些研究为连接免疫球蛋白基因转录和重排的基本机制提供了新的细节，并描绘了一幅高度动态和有序的核结构图，这将对基因调控具有重要意义。

DESCRIPTION (provided by applicant): The molecular details of how faithful DNA rearrangements are maintained in the context of the complex chromatin environment of the developing B lymphocyte is the focus of ongoing research in my lab. We have new data indicating that the IgH locus is regulated by the Ig??locus and have identified the involvement of two Ig??regulatory elements, the 3'E??enhancer and Sis (silencer in the intervening sequence. Regulation is achieved through transient association of the two loci at the pro- to pre-B cell transition when the recombinase enzymes are targeted away from the IgH locus to the Ig? locus. We aim to elucidate the functional significance of association between the two loci and to understand in molecular detail how association is achieved. It is our hypothesis that association of the IgH and Ig??loci plays a central role in enforcing allelic exclusion of the IgH locus, which is critical for maintaining the integrity of the recombination process and ensuring genome stability. Because de-regulation of recombination and allelic exclusion can result in immune deficiency, autoimmunity and translocations involving Ig loci, it is essential to understand the underlying mechanisms. In addition these studies have important implications for gene regulation as a whole. Public Health Relevance Statement: The ordered rearrangement of immunoglobulin (Ig) genes is a highly regulated process essential for adaptive immunity, orchestrating the expression of B and T lymphocyte receptors through allelic exclusion that ensures clonality, all the while protecting the genome from these inherently unstable recombination events. The molecular details of how faithful DNA rearrangements are maintained in the context of the complex chromatin environment of the developing B lymphocyte is the focus of ongoing research in my lab. Our recent studies indicate that the pericentric Ig? allele directs the unrearranged IgH allele towards a shared pericentromeric cluster. Association of the two loci in this repressive environment subsequently induces IgH locus decontraction on the non-functional allele. This identifies a novel mechanism for co-ordinating changes in accessibility and expression. The hypothesis to be tested is that association of IgH and Ig? loci plays a central role in enforcing allelic exclusion of the IgH locus, which is critical for maintaining the integrity of the recombination process and ensuring genome stability. The aims in this grant are designed to understand in molecular detail the mechanisms by which association of Ig loci contributes to allelic exclusion and genome stability. Understanding how changes at the two loci are co-ordinated and identifying the pathways involved is of fundamental importance in the field because de-regulation of recombination and allelic exclusion can result in immune deficiency, autoimmunity and translocations that involve Ig loci. These studies provide new detail to the basic mechanisms linking immunoglobulin gene transcription and rearrangement and paint a picture of a highly dynamic and ordered nuclear architecture that will have important implications for gene regulation in general.