A conserved transcriptional backbone and rewiring of gene-regulatory networks in activated human CD4? T cells
CD4+ T cells are components of the adaptive immune system with a plethora of subtype-specific functions. In order to further dissect the  activation and differentiation  regulatory program(s) of individual CD4+ T cell subsets, we performed an in vitro activation and differentiation of human primary naive CD4+ T cells towards Th1, Th2, Th17 and Treg subtypes followed by the single-cell RNA-seq and ATAC-seq (multiome) analysis.  Resulting multiome data were used for constructing the subtype-specific gene regulatory networks, which were next assessed for their differences/similarities among the subtypes.  Surprisingly, a conserved set of 8 “backbone” transcription factors (TFs) was identified as highly central in all subtypes, however, with  unique differentiation-driven rewiring tendency.  Subtype-specific “driver” TFs were identified in the case of Th1-Th1_17-Th17 lineage (EOMES, HLF), naive Tregs (ESR1, DACH1), and memory Tregs (SOX13). Finally, we applied community detection algorithms to identify potential non-obvious groups of genes that regulate diverse molecular functions within the differentiated subtypes, linked to the backbone TFs. Our atlas aims at providing a high resolution understanding of the gene regulatory networks and their  rewiring in human primary CD4+ T cells, upon activation and differentiation. Overall design: Human naive CD4+ T cells were negatively selected, stimulated under lineage-specific cytokines, and profiled using 10x Multiome; data processed with Cell Ranger ARC.