Chromatin modifications in immunoglobulin switch recombination

免疫球蛋白开关重组中的染色质修饰

• 批准号: 7734113
• 负责人: MARTIN F. GELLERT
• 金额: $ 41.97万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7734113
• 关键词: Acetylation; Allergic; Antibodies; B-Lymphocytes; Cell Proliferation; Cell surface; Cells; Chromatin; Cytidine Deaminase; Cytokine Activation; DNA Methylation; Deoxycytidine; Event; Genetic Transcription; Histone H4; Histones; Human; IL4 gene; IgE; Immunoglobulin Class Switching; Immunoglobulin Genes; Immunoglobulin Switch Recombination; Immunoglobulins; Interleukin-4; Maps; Mediating; Modification; Nucleosomes; Pattern; RNA Splicing; Relative (related person); Reporting; Resolution; TNFRSF5 gene; Transcript; Variant; Work; constant region gene; promoter; receptor; response

Switching to IgE can be activated by a combination of IL4, which induces transcription in that region, and activation of the cell surface CD40 receptor, which induces cell proliferation. Activation can be produced by anti-CD40 antibody or by a trimeric form of CD40 ligand.Our studies have focused on the human CL-01 line of B cells, which has been reported to undergo switch recombination. We have shown that IL4 causes a 100X increase in transcript, both unspliced and spliced, over the IgE switch region. We also observed a sizable (5X) increase in transcription of AID, the cytidine deaminase that is responsible for initiating CSR. A high resolution study of histone modifications in uninduced and induced CL-01 cells has been carried out, focusing on the region between the I-epsilon promoter and the 3 end of the IgE switch region, the most important region associated with this CSR event. The largest increases were found for acetyl-H3K9/14 (or acetyl-H3K9 alone) and for trimethyl-H3 K4, while other modifications including histone H4 tetra-acetylation (K5/8/12/16) and H3 K27 trimethylation were not greatly altered following IL4 induction. This pattern is consistent with broad activation of the region. Furthermore, the distribution of a given modification was in most cases non-uniform: for example, dimethyl-H3K4, tetraacetyl-H4, and acetyl-H3 K9/14 all showed relative peaks over the I-epsilon promoter. To interpret these results the abundance of nucleosomes was mapped across the same region, and a relative depletion over I-epsilon was observed, without any further change on induction. We are now extending these observations to studying the distribution of the histone variants H3.3 and H2A.Z. In addition we are studying DNA methylation in the same region. We have shown that treatment of the cells with 5-aza-deoxycytidine, a known demethylating agent, leads to an additional increase in IL4-stimulated transcription.

切换到IgE可以通过IL4的组合（诱导该区域的转录）的组合以及诱导细胞增殖的细胞表面CD40受体的激活来激活。激活可以由抗CD40抗体或三聚体形式的CD40配体产生。我们的研究集中在人体CL-01线的B细胞中，据报道，该系列的B细胞已进行开关重组。我们已经证明，IL4在IgE开关区域上的转录本（未贴合和剪接）增加了100倍。我们还观察到了负责启动CSR的胞苷脱氨酶的AID转录的大幅度（5倍）。 已经进行了对未诱导和诱导CL-01细胞的组蛋白修饰的高分辨率研究，重点是I-EPSILON启动子和IgE开关区域的3端之间的区域，IgE开关区域的3端是与该CSR事件相关的最重要区域。发现乙酰基-H3K9/14（或单独的乙酰H3K9）和三甲基-H3 K4的最大增加是，而包括组蛋白H4二乙酰基（K5/8/12/16）和H3 K27三甲基化在内的其他修饰没有大大改变IL4诱导后。这种模式与该区域的广泛激活一致。此外，在大多数情况下，给定修饰的分布是不均匀的：例如，二甲基-H3K4，四乙酰基-H4和乙酰基-H3 K9/14均显示了I-EPSILON启动子上的相对峰。为了解释这些结果，在同一区域映射了核小体的丰度，观察到I-Epsilon的相对耗竭，而没有进一步改变诱导。现在，我们将这些观察结果扩展到研究组蛋白变体H3.3和H2A.Z的分布。此外，我们正在研究同一区域的DNA甲基化。我们已经表明，用5-aza-脱氧胞苷（一种已知的脱甲基剂）治疗细胞会导致IL4刺激的转录增加。