Enhancer hijacking activates TLX3 in t(5;14) leukemia. (A) Violin plot showing TLX3 mRNA expression in t(5;14)-containing samples vs other samples without t(5;14). (B) Genome browser tracks for ATAC-seq, H3K27ac ChIP-seq, RNA-seq, and 4C-seq for t(5;14)-positive (DND-41, UT242, and UT308) and t(5;14)-negative (Jurkat, HNT-34, and GM12878) cells. The purple arrowhead indicates the 4C-seq viewpoint. Coordinates correspond to hg19 genome assembly. Jurkat, HNT-34, and GM12878 represent negative controls for T-lymphoid, myeloid, and B-lymphoid lineages, respectively. (C) Schematic overview of CRISPRi-mediated perturbation of the BCL11B enhancers or the TLX3 transcription start site (TSS). (D) Expression of TLX3 mRNA upon CRISPRi-mediated enhancer and promoter repression in DND-41 cells normalized to GAPDH. Results are mean ± standard deviation (SD) (N = 3 biological replicates) and were analyzed by a Student t test. ∗∗P < .01, ∗∗∗∗P < .0001. (E) Schematic representation of enhancer hijacking for TLX3 activation in t(5;14) leukemia.