A single TCF transcription factor, regardless of its activation capacity, is sufficient for effective trilineage differentiation of ES cells

Co-expression and cross-regulation of the four TCF/LEFs render their redundant and unique functions ambiguous. Here, we describe quadruple-knockout (QKO) mouse ES cells lacking all full-length TCF/LEFs and cell lines rescued with TCF7 or TCF7L1. QKO cells self-renew, despite gene expression patterns that differ significantly from WT, and display delayed, neurectoderm-biased, embryoid body (EB) differentiation. QKO EBs have no contracting cardiomyocytes and differentiate poorly into mesendoderm, but readily generate neuronal cells. QKO cells and TCF7L1-rescued cells cannot efficiently activate TCF reporters, whereas TCF7-rescued cells exhibit significant reporter responsiveness. Surprisingly, despite dramatically different transactivation capacities, re-expression of TCF7L1 or TCF7 in QKO cells restores their tri-lineage differentiation ability, with similar lineage marker expression patterns and beating cardiomyocyte frequencies observed in EBs. Both factors also similarly affect the transcriptome of QKO cells. Our data reveal that a single TCF, regardless of its activation capacity, is sufficient for effective trilineage differentiation of ES cells. Overall design: Total RNA was isolated from mouse ES cells lacking all full-length TCF/LEFs (Quadruple Knock Outs) and QKOs rescued with a single copy of TCF7 or TCF7L1 compared to wildtype E14TG2a mouse ES cells, cultured for 48 hours in 15% serum + LIF.