Journal: bioRxiv
Article Title: Enhancer hubs govern chromatin topology and Th17 identity
doi: 10.64898/2026.04.02.715458
Figure Lengend Snippet: a) Schematic of project design. Stage 1: Isolate ATAC-seq fragments from in vitro derived Th0, Th1, Th2, Th17 and Treg CD4+ subsets to build ATAC-STARR-seq libraries. Stage 2: Assay all the unified pool of CD4+ OCRs in each CD4+ subset. Stage 3: Endogenous perturbations of Th17 OCRs using CRISPR-based epigenome editing screens. Stage 4: in vitro and in vivo validation of Th17 enhancer function followed by flow cytometry readouts for cell phenotype b) Genome browser track depicting the union ATAC-STARR-seq input library (grey) and STARR-seq activity score (Log2 CPM RNA/DNA; coloured) at the Bach2 locus for each subset. c) Upset plot of OCR intersections between all CD4 T cell subsets, with the proportion of STARR-seq active OCRs for each intersection highlighted in yellow. d) Stacked bar plots indicating the total number of OCRs tested in ATAC-STARR-seq and the proportion of OCRs with significant STARR-seq activity in that subset (dark colour), any subset (light colour) or tested but not significant (grey; fdr < 0.05). e) Total STARR-seq enhancer calls by subset (FDR < 0.05) with the proportion of functional OCRs by chromatin category (Subset shared = purple; multiple subsets = blue; subset unique = red) f) Effect sizes of significant enhancer calls for each cell type (Log2 RNA/DNA) g) Genome annotation of OCRs mapped by ATAC-seq (grey) or functional OCRs determined by STARR-seq (active = red; repressive = blue) for each subset. h) Violin plot showing distribution and median transcript abundance of genes nearest to OCRs categorized by ATAC-STARR-seq enhancer call significance for that subset (sig = STARR FDR < 0.05; n.s = non-significant; all p ∼ 0 for sig vs n.s, Mann-Whitney U Test) i) Radial plot of STARR-seq regulatory activity preference across CD4+ T cell subsets. Each axis represents a tested subset (Th0, Th1, Th2, Th17, Treg), and each point represents an active OCR with significant STARR-seq activity in at least one subset (FDR < 0.01). A weighted activity score (|Log2FC| x -log10(FDR)) of each OCR was calculated for each subset, normalized to sum to one across all subsets, and projected into 2D using angular coordinates. OCRs with STARR-seq activity biased toward a single subset fall near the corresponding spoke, while OCRs with equivalent activity across subsets fall near the center. Points are coloured by the subset in which the OCR exhibits its highest activity score. j) Odds ratio of top enriched motif families at subset-preferred OCRs. For each enhancer-preference group (subset-preferred, r = 0.85; subset-shared, r=0.3), odds ratios were computed for the preferred OCR set against all others. Top motif families are shown.
Article Snippet: Specifically, we empirically determined MNase (Worthington Biochemical, Cat #LS004797) chromatin fragmentation conditions for Naïve and Th17 cells to be 2U MNase for 12 minutes at 37C per 1M cells.
Techniques: In Vitro, Derivative Assay, CRISPR, In Vivo, Biomarker Discovery, Flow Cytometry, Activity Assay, Functional Assay, MANN-WHITNEY