Scatter factor/hepatocyte growth factor and its receptor, the c-met tyrosine kinase, can mediate a signal exchange between mesenchyme and epithelia during mouse development.

TLDR

Scatter factor/hepatocyte growth factor (SF/HGF) is a potent motogenic, mitogenic, and morphogenetic factor for epithelial cells that signals through its receptor c‑met, a receptor‑type tyrosine kinase, and mesenchymal signals are known to govern epithelial differentiation and morphogenesis, though their molecular identity has been unclear. The study reports novel, distinct expression patterns of SF/HGF and its receptor during mouse development using in situ hybridization and RNase protection. During mouse development, c‑met transcripts are found in epithelial cells of multiple organs while SF/HGF is expressed in adjacent mesenchymal cells, with transient expression also observed at muscle formation sites and in developing motoneurons. These expression patterns suggest that SF/HGF and c‑met mediate mesenchymal‑to‑epithelial signaling during development, playing multiple roles in morphogenesis.

Abstract

Scatter factor/hepatocyte growth factor (SF/HGF) has potent motogenic, mitogenic, and morphogenetic activities on epithelial cells in vitro. The cell surface receptor for this factor was recently identified: it is the product of the c-met protooncogene, a receptor-type tyrosine kinase. We report here the novel and distinct expression patterns of SF/HGF and its receptor during mouse development, which was determined by a combination of in situ hybridization and RNase protection experiments. Predominantly, we detect transcripts of c-met in epithelial cells of various developing organs, whereas the ligand is expressed in distinct mesenchymal cells in close vicinity. In addition, transient SF/HGF and c-met expression is found at certain sites of muscle formation; transient expression of the c-met gene is also detected in developing motoneurons. SF/HGF and the c-met receptor might thus play multiple developmental roles, most notably, mediate a signal given by mesenchyme and received by epithelial. Mesenchymal signals are known to govern differentiation and morphogenesis of many epithelia, but the molecular nature of the signals has remained poorly understood. Therefore, the known biological activities of SF/HGF in vitro and the embryonal expression pattern reported here indicate that this mesenchymal factor can transmit morphogenetic signals in epithelial development and suggest a molecular mechanism for mesenchymal epithelial interactions.