Chromosome movements that regulate tissue-specific gene expression

在2014财年，我们完成了以下工作： 1.完成了免疫球蛋白基因座组织特异性染色体构象的逐步建立研究。具体地说，我们发现依赖于CTCF的位置压缩相互作用不需要Pax5或E。然而，依赖于E的长程相互作用需要YY1和Pax5。所有环的形成只在B系细胞中发生。这些研究是与Ann Feeney博士(圣地亚哥斯克里普斯研究所)合作进行的。 2.我们发展了3-4kb FISH探针用于高分辨率FISH研究染色体构象。我们利用这些探针分别研究了12号和15号染色体上的IgH和c-Myc基因座之间的染色体间相互作用。 3.对老年小鼠原代骨髓PRO-B细胞进行了IgH基因位点构象分析。初步实验表明，陈旧的PRO-B细胞中的轨迹致密程度严重减弱。这种去紧密化可能会导致VDJ重组的效率随着年龄的增加而降低，并导致可用于有效免疫的B细胞库减少。

During FY14 we accomplished the following: 1. Completed studies on the step-wise establishment of tissue-specific chromosome conformation of the IgH locus. Specifically we found the CTCF-dependent locus compacting interactions did not require Pax5 or E. However E-dependent long-range interactions required both YY1 and Pax5. All loop formation occurred only in B lineage cells. These studies were carried out in collaboration Dr. Ann Feeney (The Scripps Research Institute, San Diego). 2. We developed the use of 3-4kb FISH probes for high resolution FISH studies of chromosome conformation. We used these probes to study inter-chromosomal interaction between IgH and c-Myc loci on chromosomes 12 and 15, respectively. 3. We assayed IgH locus conformation in primary bone marrow pro-B cells from old mice. Preliminary experiments indicate severely attenuated locus compaction in old pro-B cells. Such de-compaction may lead to reduced efficiency of VDJ recombination with age, and result in a smaller repertoire of B cells available for effective immunity.