At the end of gastrulation in avians and mammals, the endoderm germ layer is an undetermined sheet of cells. Over the next 24-48 h, endoderm forms a primitive tube and becomes regionally specified along the anterior-posterior @entity2270 . @entity10008 is expressed in gastrulation and somite stage embryos in the vicinity of posterior endoderm that gives rise to the posterior gut. Moreover, the posterior endoderm adjacent to @entity10008 -expressing mesoderm expresses the FGF-target genes @entity5743 suggesting that endoderm respond to an FGF signal in vivo. Here, we report the first evidence suggesting that @entity10008 -mediated signaling is required for establishing gut tube domains along the A-P @entity2270 in vivo. At the gastrula stage, exposing endoderm to recombinant @entity10008 protein results in an anterior shift in the @entity5908 and CdxB expression domains. These expression domains remain sensitive to @entity10008 levels throughout early somite stages. Additionally, @entity10008 represses the anterior endoderm markers @entity38984 and @entity7457 and disrupts foregut morphogenesis. FGF signaling directly patterns endoderm and not via a secondary induction from another germ layer, as shown by expression of dominant-active @entity7167 specifically in endoderm, which results in ectopic anterior expression of @entity5908 . Loss-of-function studies using the FGF receptor antagonist @entity7795 demonstrate that FGF signaling is necessary for establishing midgut gene expression and for maintaining gene expression boundaries between the midgut and hindgut from gastrulation through somitogenesis. Moreover, FGF signaling in the primitive streak is necessary to restrict @entity38984 expression to anterior endoderm. These data show that FGF signaling is critical for patterning the gut tube by promoting posterior and inhibiting anterior endoderm cell fate.

FGF signaling is necessary for establishing gut tube domains along the anterior-posterior XXXX in vivo.

@entity5908 :: ('3651', 'Gene') :: ['Pdx1'] @entity5743 :: ('10253', 'Gene') :: ['Sprouty1 and 2'] @entity7795 :: ('MESH:C105686', 'Chemical') :: ['SU5402'] @entity7457 :: ('7080', 'Gene') :: ['Nkx2.1'] @entity2270 :: ('MESH:C566610', 'Disease') :: ['axis'] @entity10008 :: ('2249', 'Gene') :: ['Fgf4', 'FGF4'] @entity7167 :: ('2260', 'Gene') :: ['FGFR1'] @entity38984 :: ('9156', 'Gene') :: ['Hex1']
@entity2270 :: (MESH:C566610,Disease) :: ['axis']
