CHARACTERIZATION OF RAT EPIMORPHIN SYNTAXIN-2 EXPRESSION SUGGESTS A ROLE IN CRYPT-VILLUS MORPHOGENESIS/

The rodent intestinal mucosa undergoes a remarkable morphogenesis as t he crypt-villus axis is formed. Endoderm-mesenchymal interactions play a critical role in this process. Epimorphin is a mesenchymal protein postulated to play a role in lung and skin morphogenesis. The rat homo logue, syntaxin 2, belongs to a family of integral membrane proteins t hat function in vesicle docking and fusion. To clarify its role in fet al gut morphogenesis, epimorphin expression was examined during ontoge ny, in an isograft model of ischemic injury and mucosal repair, and du ring intestinal adaptation after small bowel resection. Epimorphin/syn taxin 2 mRNA levels were increased in fetal gut during lumen formation and villus morphogenesis. mRNA levels remained elevated in the first 2 wk after birth and then declined at weaning. In situ hybridization s howed epimorphin/ syntaxin 2 mRNA in gestational day 14 (G14) and G15 intestinal mesenchymal cells and in the mucosal lamina propria during villus formation. Epimorphin/syntaxin 2 mRNA expression increased duri ng villus repair in the isograft. In contrast, in the early stages of intestinal adaptation after small bowel resection, epimorphin/syntaxin 2 mRNA expression was suppressed in the adapting gut. We conclude the cell-specific and temporal patterns of epimorphin expression in the m odels used in this study suggest a role in the morphogenesis of the cr ypt-villus axis.