Organization and regulation of the human insulin locus

我们正在对人类胰岛细胞中胰岛素基因位点及其邻域的组蛋白修饰进行研究，试图确定可能影响胰岛素基因表达的长期调节影响。我们正在进行胰岛素启动子和其他基因组位点之间的长距离物理接触的测量。为了检测这种相互作用，我们在人类胰岛上进行了4C（扩展染色质构象捕获）实验，绘制了细胞核内Ins启动子与11号染色体上远端位点之间的接触图谱。我们选择了Syt8 （synaptotagmin 8）基因作为进一步研究的候选基因，该基因与胰岛素位点一样，在附近有一个CTCF结合位点。我们在论文中表明，Ins- syt8接触是存在的，它们被添加葡萄糖刺激，当Ins启动子被阻断以沉默Ins基因活性时被抑制。接触增加与Syt8表达增加相关。CTCF的缺失导致接触缺失和Syt8（不包括Ins）表达缺失。此外，我们发现Syt8的消耗导致胰岛胰岛素分泌减少。这些结果揭示了导致耦合调节控制的远程相互作用的物理网络。这些类型的调控网络似乎在整个基因组中都存在。本文所描述的方法可以应用于其他基因座。

We are carrying out studies of the histone modifications over the insulin gene locus and its neighborhood in human islet cells, in an attempt to identify long range regulatory influences that may affect insulin gene expression. We are carrying out measurements of long range physical contacts within the nucleus between the insulin promoter and other genomic sites. To detect such interactions we carried out 4C (an extended chromatin conformation capture) experiments in human islets, to map contacts within the nucleus between the Ins promoter and distant sites on chromosome 11. We selected for further study a single candidate, the synaptotagmin 8 (Syt8) gene, which like the insulin locus, has a nearby CTCF binding site. We show in this paper that Ins-Syt8 contacts are present, that they are stimulated by addition of glucose and inhibited when the Ins promoter is blocked to silence Ins gene activity. Increased contact is correlated with increased Syt8 expression. Depletion of CTCF results in loss of contact and loss of Syt8 (but not Ins) expression. Furthermore, we show that depletion of Syt8 results in decreased secretion of insulin from the islets. These results reveal a physical network of long range interactions that leads to coupled regulatory control. It seems likely that these kinds of regulatory networks occur throughout the genome. The methods described in this paper can be applied to other loci.