Solinhac Romain, Mompart Florence, Martin Pascal, Robelin David, Pinton Philippe, Iannuccelli Eddie, Lahbib-Mansais Yvette, Oswald Isabelle P, Yerle-Bouissou Martine
Laboratoire de Génétique Cellulaire, INRA, Castanet-Tolosan, France.
Chromosoma. 2011 Oct;120(5):501-20. doi: 10.1007/s00412-011-0328-7. Epub 2011 Jun 22.
Changes in the nuclear positioning of specific genes, depending on their expression status, have been observed in a large diversity of physiological processes. However, gene position is poorly documented for immune cells which have been subjected to activation following bacterial infection. Using a pig model, we focused our study on monocyte-derived macrophages and neutrophils, as they are the first lines of defence against pathogens. We examined whether changes in gene expression due to LPS activation imply that genes have repositioned in the nuclear space. We first performed a transcriptomic analysis to identify the differentially expressed genes and then analysed the networks involved during lypopolysaccharide/interferon gamma activation in monocyte-derived macrophages. This allowed us to select four up-regulated (IL1β, IL8, CXCL10 and TNFα) and four down-regulated (VIM, LGALS3, TUBA3 and IGF2) genes. Their expression statuses were verified by quantitative real-time RT-PCR before studying their behaviour in the nuclear space during macrophage activation by means of 3D fluorescence in situ hybridization. No global correlation was found between gene activity and radial positioning. Only TNFα belonging to the highly transcribed MHC region on chromosome 7 became more peripherally localized in relation to the less decondensed state of its chromosome territory (CT) in activated macrophages. The analysis of gene positioning towards their CT revealed that IL8 increases significantly its tendency to be outside its CT during the activation process. In addition, the gene to CT edge distances increase for the three up-regulated genes (IL8, CXCL10 and TNFα) among the four analysed. Contrarily, the four down-regulated genes did not change their position. The analysis of gene behaviour towards their CT was extended to include neutrophils for three (TNFα, IL8 and IL1β) up- and two (IGF2 and TUBA3) down-regulated genes, and similar results were obtained. The analysis was completed by studying the four up-regulated genes in fibroblasts, not involved in immune response. Our data suggest that relocation in the nuclear space of genes that are differentially expressed in activated immune cells is gene and cell type specific but also closely linked to the entire up-regulation status of their chromosomal regions.
在多种生理过程中，已观察到特定基因的核定位会根据其表达状态而发生变化。然而，对于细菌感染后被激活的免疫细胞，基因定位的相关记录却很少。利用猪模型，我们将研究重点放在单核细胞衍生的巨噬细胞和中性粒细胞上，因为它们是抵御病原体的第一道防线。我们研究了脂多糖（LPS）激活导致的基因表达变化是否意味着基因在核空间中重新定位。我们首先进行了转录组分析以鉴定差异表达基因，然后分析了单核细胞衍生的巨噬细胞在脂多糖/干扰素γ激活过程中涉及的网络。这使我们能够选择四个上调基因（IL1β、IL8、CXCL10和TNFα）和四个下调基因（VIM、LGALS3、TUBA3和IGF2）。在通过三维荧光原位杂交研究它们在巨噬细胞激活过程中的核空间行为之前，通过定量实时RT-PCR验证了它们的表达状态。未发现基因活性与径向定位之间存在全局相关性。只有位于7号染色体上高度转录的MHC区域的TNFα，在激活的巨噬细胞中，与其染色体区域（CT）较少凝聚的状态相关，其定位更偏向于外周。对基因相对于其CT的定位分析表明，IL8在激活过程中显著增加了其位于CT外部的趋势。此外，在所分析的四个基因中，三个上调基因（IL8、CXCL10和TNFα）的基因到CT边缘的距离增加。相反，四个下调基因的位置没有改变。对基因相对于其CT的行为分析扩展到包括中性粒细胞中的三个上调基因（TNFα、IL8和IL1β）和两个下调基因（IGF2和TUBA3），并获得了类似的结果。通过研究不参与免疫反应的成纤维细胞中的四个上调基因完成了分析。我们的数据表明，激活的免疫细胞中差异表达基因在核空间中的重新定位是基因和细胞类型特异性的，但也与其染色体区域的整体上调状态密切相关。
