The LHX1 Gene Regulatory Network Represses Pluripotency to Specify the Embryonic Head
The development of the embryonic head in mice relies on the activity of the transcription factor LIM homeobox 1 (LHX1) in the anterior epiblast.  In this study, we sought to unravel the molecular role of LHX1 during and immediately following gastrulation. We utilized  CRISPR-Cas9 gene editing in embryo models as well as DamID-seq, RNA-seq, and ATAC-seq in mouse embryos. These techniques enabled us to reveal the genome wide targets of LHX1 for the first time in gastrulation stage mouse embryos. Integrated analysis of the omics datasets uncovered that LHX1 is instrumental in decommissioning the pluripotency network and determining the anterior fate of the precursor tissue of the embryonic head. We found that LHX1 directly binds to and regulates genes involved in WNT and FGF signaling pathway inhibition. We also identified a downstream target of LHX1, Kctd1, expressed in the anterior tissue, which acts to modulate canonical WNT activity. These findings identified a component of the gene regulatory network anchored by LHX1 that governs the development of the embryonic head. Overall design: RNA-seq was run on day zero, two, four and six embryoid bodies derived from wild type (R1 ESC) or Lhx1-knockout Lhx1KO mouse embryonic stem cells.