Total expression profiling of embryonic regions of EHF mouse embryos

Establishment of left-right (LR) asymmetry occurs shortly after gastrulation and utilizes a cascade of events. In the mouse, LR symmetry is broken at the node, involves signal relay to the lateral plate, and results in asymmetric organ morphogenesis. How information transmits from the node to the lateral plate remains unclear. Noting that embryos lacking Sox17 exhibit defects in both gut endoderm formation and LR patterning, we investigated a connection between these two processes. We noted an endoderm-specific absence of the critical gap junction component, Connexin43, in Sox17 mutants. Dye-coupling experiments revealed planar gap junction coupling across the gut endoderm in wild-type but not mutant embryos. The role for gap junction communication in LR patterning was confirmed by pharmacological inhibition. Collectively, our data demonstrate communication across gap junctions in gut endoderm as a mechanism for information relay between node and lateral plate critical for the establishment of LR asymmetry in mice. Total RNA isolated from embryonic regions of wild-type embryos at EHF stages, three samples per well, in triplicates