Isotype specific regulation of lg class switching

LG 类别转换的同种型特异性调节

• 批准号: 6965565
• 负责人: Janet M. Stavnezer
• 金额: $ 32.4万
• 依托单位: UNIV OF MASSACHUSETTS MED SCH WORCESTER
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-15 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6965565
• 关键词: B lymphocyte; DNA binding protein; chromatin immunoprecipitation; flow cytometry; gene rearrangement; genetic transcription; immunoglobulin A; immunoglobulin genes; immunoglobulin isotypes; laboratory mouse; methyltransferase; protein binding; tissue /cell culture

DESCRIPTION (provided by applicant): Upon activation by antigen, B cells undergo antibody class (isotype) switching, changing from expression of IgM to expression of IgG, IgA or IgE, while maintaining specificity for the same antigen. Since the isotype determines the effector function of the antibody, class switching allows the humoral immune response to adaptively respond to different infectious organisms. Class switching occurs by a DNA recombination event between switch (S) region sequences located upstream of each heavy chain constant (Ch) region gene. Numerous studies (including many from this laboratory) have established that transcription of specific unrearranged Ch genes occurs prior to switching and that this transcription is required for switching. Recent data, however, indicate that isotype specificity of switch recombination is regulated at additional undefined levels. Regulation of IgA switching is especially mysterious because it can only be induced to low levels in culture and yet is the most abundant antibody class in the body, expressed specifically in mucosal tissues. IgA is an important first line of defense against pathogens entering through body orifices. Data from our lab indicate that LSF/CP2/LBP-1c binds the switch (S) region DNA sequences associated with the IgA Ch gene and regulates switching to IgA in the l.29u B cell line. We have also found that the histone methyltransferase Suv39h1 specifically increases IgA switching in a plasmid switch substrate. The goal of this proposal is to investigate the mechanism of this regulation and to provide evidence for the hypothesis that chromatin accessibility and histone modifications of specific S regions regulate class switch recombination. In Aim 1 we propose to investigate the role of Suv39h1 in endogenous switch recombination and the mechanism of its function. We will investigate the hypothesis that Suv39h1 inhibits the activity of a sequence-specific DNA binding protein to repress switch recombination to IgA. The most likely candidate for this inhibitory protein is LSF/CP-2/LBP-1c, which is known to bind histone deacetylases and polychrome group proteins. Aim 2 will be to determine whether LSF specifically inhibits IgA switch recombination in normal splenic B cells and to examine the mechanism of inhibition of IgA switching by LSF.

描述（由申请方提供）：在被抗原激活后，B细胞经历抗体类别（同种型）转换，从IgM表达变为IgG、伊加或IgE表达，同时保持对相同抗原的特异性。由于同种型决定了抗体的效应子功能，类别转换允许体液免疫应答适应性地应答不同的感染性生物体。类别转换通过位于每个重链恒定（Ch）区基因上游的转换（S）区序列之间的DNA重组事件发生。许多研究（包括本实验室的许多研究）已经确定，特定的未重排Ch基因的转录发生在转换之前，并且这种转录是转换所必需的。然而，最近的数据表明，开关重组的同种型特异性在其他未定义的水平进行调节。伊加转换的调节是特别神秘的，因为它只能在培养物中被诱导到低水平，但它是体内最丰富的抗体类别，特异性地在粘膜组织中表达。伊加是抵抗病原体通过身体孔口进入的重要的第一道防线。来自我们实验室的数据表明，LSF/CP 2/LBP-1c结合与伊加Ch基因相关的开关（S）区DNA序列，并调节l.29 u B细胞系中向伊加的转换。我们还发现组蛋白甲基转移酶Suv 39 h1特异性地增加了质粒开关底物中的伊加开关。本提案的目的是调查这种调节的机制，并提供证据的假设，染色质的可及性和组蛋白修饰的特定S区调节类转换重组。在目的1中，我们提出研究Suv 39 h1在内源性开关重组中的作用及其功能机制。我们将研究Suv 39 h1抑制序列特异性DNA结合蛋白的活性以抑制开关重组为伊加的假设。这种抑制蛋白最可能的候选者是LSF/CP-2/LBP-1c，已知其结合组蛋白脱乙酰酶和多色组蛋白。目的2将确定LSF是否特异性抑制正常脾B细胞中的伊加转换重组，并检查LSF抑制伊加转换的机制。