Single-cell RNA-seq of wild-type and Pbx1/Pbx2 double-knockout EpiSCs differentiated in vitro to pre-somitic mesoderm in the first 48 hours of differentiation.

In vertebrates, body axis elongation is fuelled by bipotent neuromesodermal progenitors (NMPs), which support the development of both spinal cord and paraxial mesoderm (PM). HOX transcription factors have been historically implicated in axial elongation, with their sequential activation playing a fundamental role in timing PM development. PBX1 and PBX2 are obligate anterior HOX cofactors, and therefore they represent prominent candidates for controlling the distinct response to individual HOX factors. To pinpoint the role of PBX proteins in the development of pre-somitic mesoderm (PSM), wild-type (WT) and Pbx1/Pbx2 double-mutant (Pbx1/2-DKO) EpiSCs were differentiated in vitro to PSM. Single cells from different time-points (WT: EpiSCs, 6 hours, 12 hours, 24 hours, 36 hours, 48 hours; Pbx1/2-DKO: 24 hours, 36 hours, 48 hours) were FACS-sorted into 384-well capture plates, and single-cell RNA-sequencing was performed using MARS-seq (Jaitin D.A. et al., Science, 343, 776-779 (2014)). Two wells were left empty in each plate, as a no-cell control during data analysis.