The epigenetic reader BRWD1 in peripheral adaptive immunity

项目摘要 最近，我们证明了含有表观遗传阅读器的谱系限制性BROMO和WD 40结构域， BRWD 1打开Igk并诱导表观遗传景观，使RAG蛋白能够在Jk组装。我们现在 BRWD 1在晚期B细胞发育中具有更广泛的作用。BRWD 1重塑染色质景观 通过关闭在B细胞发育早期表达的基因的增强子和打开在B细胞发育早期表达的基因的增强子， 晚期BRWD 1不影响关键转录因子（TF）的表达。相反，如图所示， 对于IRF 4，BRWD 1决定了它们在整个基因组中结合的位点。BRWD 1差异调节超过7000 基因，抑制增殖和诱导分化程序。值得注意的是，BRWD 1协同抑制 Myc和Myc靶基因。此外，在人类中，BRWD 1突变与以下疾病相关： 低丙种球蛋白血症这些数据表明，在小鼠和人类中，BRWD 1都是一个主协调者。 增强子可及性，与TF网络合作驱动晚期B细胞发育。 BRWD 1首先在小的前B细胞中表达。然而，Brwd 1在幼稚卵泡（FO）中的表达更高。 在生发中心（GC）暗区（DZ）细胞中。GC DZ和光照差异表达基因分析 区（LZ）细胞，与小前B细胞中BRWD 1差异调节的细胞相比，预测BRWD 1 抑制DZ程序并诱导LZ程序。此外，差异基因组范围的结合， BRWD 1在DZ和LZ细胞中的表达表明在每个GC亚群中具有不同的功能。免疫Brwd 1fl/fl x Aicda（AID）- Cre小鼠揭示BRWD 1是正常抗体同种型转换和亲和力成熟所必需的。 在组织学上，GC的大小和数量都大大减少，并且缺乏滤泡树突状细胞。因此，我们认为， 我们假设BRWD 1调节表观遗传状态和对DZ协调至关重要的增强子景观， 和LZ转录程序和GC功能。我们将在以下具体目标中检验这一假设： 目标1。确定正常生发中心反应的转录调节。 目标2.确定BRWD 1在获得性免疫中的作用。 目标3。确定BRWD 1在启动GC反应和维持FO B细胞身份中的作用。!

PROJECT SUMMARY Recently, we demonstrated that the lineage-restricted BROMO and WD40 domain containing epigenetic reader BRWD1 opens Igk and induces an epigenetic landscape that enables assembly of RAG proteins at Jk. We now report that BRWD1 has a much broader role in late B cell development. BRWD1 reshapes chromatin landscapes by closing enhancers of genes expressed early in B cell development and opening those of genes expressed in late stages. BRWD1 did not affect the expression of critical transcription factors (TFs). Rather, as demonstrated for IRF4, BRWD1 determines the sites they bind across the genome. BRWD1 differentially regulated over 7000 genes, repressing proliferative and inducing differentiation programs. Notably, BRWD1 coordinately repressed Myc and Myc target genes. Furthermore, in humans, BRWD1 mutations are associated with hypogammaglobulinemia. These data indicate that, in both mice and humans, BRWD1 is a master orchestrator of enhancer accessibility that cooperates with TF networks to drive late B cell development. BRWD1 is first expressed in small pre-B cells. However, Brwd1 expression is higher in naïve follicular (FO) and in germinal center (GC) dark zone (DZ) cells. Analysis of genes differentially expressed in GC DZ and light zone (LZ) cells, compared to those differentially regulated by BRWD1 in small pre-B cells, predicts that BRWD1 represses the DZ program and induces the LZ program. Furthermore, differential genome-wide binding of BRWD1 in DZ and LZ cells suggests different functions in each GC subset. Immunizing Brwd1fl/fl x Aicda (AID)- Cre mice revealed that BRWD1 was required for normal antibody isotype switching and affinity maturation. Histologically, GCs were greatly reduced in both size, and number, and lacked follicular dendritic cells. Therefore, we hypothesize that BRWD1 regulates epigenetic states and enhancer landscapes critical for coordination of DZ and LZ transcriptional programs and GC function. We will test this hypothesis in the following Specific Aims: Aim 1. Determine the transcriptional regulation of normal germinal center responses. Aim 2. Determine the role of BRWD1 in adaptive immunity. Aim 3. Determine the role of BRWD1 in initiating GC responses and in maintaining FO B cell identity. !