Regulation of laminin gene expression in preimplantation mammalian development by COUP-TF

The deposition of a basement membrane by primitive endoderm cells is necessary for polarization of the epiblast and formation of the proamniotic cavity in periimplantation mammalian embryos. The synthesis of this basement membrane is in turn dependent upon laminin expression. Here we have used embryoid bodies derived from mouse embryonic stem cells to investigate the molecular mechanisms controlling laminin gene expression in differentiating primitive endoderm cells. We demonstrate that COUP-TFs are dramatically up-regulated in primitive endoderm cells, and that these factors are sufficient to induce expression of LAMB1 and LAMC1 genes. These results indicate that COUP-TFs play a hitherto unsuspected role in early embryonic development by regulating basement membrane deposition.