Notochord to endoderm signaling is required for pancreas development

TLDR

The notochord is known to induce and pattern adjacent neural and mesodermal tissues. Our experiments show that the notochord is essential for early pancreatic specification, as its removal abolishes dorsal pancreas markers and its presence can induce pancreatic genes in prepancreatic endoderm but not in non‑pancreatic endoderm, indicating a permissive, stepwise signaling role.

Abstract

ABSTRACT The role of the notochord in inducing and patterning adjacent neural and mesodermal tissues is well established. We provide evidence that the notochord is also required for one of the earliest known steps in the development of the pancreas, an endodermally derived organ. At a developmental stage in chick embryos when the notochord touches the endoderm, removal of notochord eliminates subsequent expression of several markers of dorsal pancreas bud development, including insulin, glucagon and carboxypeptidase A. Pancreatic gene expression can be initiated and maintained in prepancreatic chick endoderm grown in vitro with notochord. Non-pancreatic endoderm, however, does not express pancreatic genes when recombined with the same notochord. The results suggest that the notochord provides a permissive signal to endoderm to specify pan-creatic fate in a stepwise manner.