Induced repatterning of type XVIII collagen associates with ectopic Sonic hedgehog and lung surfactant C gene expression and changes in epithelial epigenesis in the ureteric bud.

How cell and tissue interactions lead to complex organ structures and differentiated cell types during organogenesis is one of the most fundamental questions in developmental biology. The embryonic lung and kidney of the mouse are useful models for studying the molecular mechanisms of morphogenesis, and in both of these organs, the epithelial bud undergoes a characteristic branching process. This review discusses the potential role of an extracellular matrix molecule, type XVIII collagen, in the generation of the branching patterns in the lung and kidney and how its experimental respecification in tissue recombinants between the ureteric bud and lung mesenchyme correlates with changes in expression of signaling molecules such as sonic hedgehog and changes in cell fate as judged by ectopic expression of the lung surfactant C gene.