Transcriptomic and nuclear architecture of immune cells after LPS-activation

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 in immune cells subjected to activation upon bacterial infection. Using the pig as a model organism, we focused our study on monocytes-derived macrophages and neutrophils, the first lines of defense against pathogens. We examine whether changes in gene expression due to LPS-activation imply genes repositioning in the nuclear space. A transcriptomic analysis was first performed to identify the genes differentially expressed and analyse the networks implicated during LPS-IFNγ activation in monocytes-derived macrophages. This allowed us to select 4 up-regulated (IL1β, IL8, CXCL10 and TNFα) and 4 down-regulated (VIM, LGALS3, TUBA3, and IGF2) genes to be further studied by 3D-FISH for their behavior in the nuclear space, particularly towards their chromosome territories (CT) during macrophages activation. Among the 4 up-regulated genes, 3 changed their position during the activation process while the 4 down-regulated ones did not. The analysis of gene behaviors towards their CT was extended to neutrophils for 3 up- and 2 down-regulated genes and similar results were obtained. Our data suggest that relocation in the nuclear space of genes differentially expressed in activated immune cells is gene specific and concern mostly up-regulated ones. Porcine monocyte-derived macrophages: Control vs. LPS-IFNγ activated vs. T-2 toxin/LPS-IFNγ activated. A common reference hybridization scheme was used to compare the three-condition experiment, CM vs. AM vs. TAM. The reference consisted of a pool of RNA from all samples. Biological replicates: 5 control, 5 LPS-IFNγ activated, 5 T-2 toxin/LPS-IFNγ activated independently. One replicate per array.