Isoforms of the TAL1 transcription factor have different roles in hematopoiesis and cell growth
Fig 4
TAL1-short promotes transcription of apoptotic genes and is a stronger transcription factor compared to TAL1-long. (A-H) Jurkat cells were infected with empty vector, FLAG-TAL1-short or FLAG-TAL1-long. FLAG was immunoprecipitated and known TAL1 interacting proteins were detected with indicated antibodies (A). (B-H) FLAG-TAL1-short, TAL1-long, and empty vector’s chromatin were immunoprecipitated using FLAG antibody. In addition, TAL1-total ChIP-seq data were analyzed (see methods). Heatmap showing signal enrichment over 5,876 TAL1-total binding sites (±1,000 kb from the center). Heatmap is sorted by strength of TAL1-short signal centered on ChIP-seq summits. A color scale indicating the relative signal intensity plotted on each heatmap is shown (B). ChIP-seq average signal for TAL1-total, TAL1-short, and TAL1-long and empty vector as a function of distance from TAL1-total peaks (C). Most abundant DNA sequence motifs were identified in TAL1-total, TAL1-short, and TAL1-long ChIP-seq peaks. Percentage of loci was calculated by dividing % of target sequences with motifs by % of background sequences with the motif for ETS (D), GATA (E), RUNX (F), MAF (G), and E-box (H). (I-L) Jurkat cells were infected with inducible shRNA against the 3′ UTR of TAL1. In addition, the cells were infected with either empty vector, TAL1-short or TAL1-long. Following induction with tetracycline for 72 h, RNA was extracted and subjected to sequencing. In addition, analysis was performed on available data of TAL1-total (see methods). Venn diagram representing the overlap of TAL1-short, TAL1-long, and TAL-total target genes (I). Gene Set Enrichment Analysis (GSEA) for apoptotic pathway for TAL1-short and TAL1-long (J). Cells were seeded and counted every day following labeling by trypan blue. Live cells are plotted in (K); trypan blue-labeled cells are plotted in (L). Plots represents the mean of 3 independent experiments (*P < 0.05, ***P < 0.001, and ****P < 0.0001 Student t test). Underyling data can be found in S1 Data and S1 Raw Images.