Craniofacial defects in mice lacking BMP type I receptor Alk2 in neural crest cells.

Neural crest cells (NCCs) are pluripotent migratory cells that contribute to the development of various craniofacial structures. Many signaling molecules have been implicated in the formation, migration and differentiation of NCCs including bone morphogenetic proteins (BMPs). BMPs signal through a receptor complex composed of type I and type II receptors. Type I receptors (Alk2, Alk3 and Alk6) are the primary determinants of signaling specificity and therefore understanding their function is important in revealing the developmental roles of molecular pathways regulated by BMPs. Here we used a Cre/loxP system for neural crest specific deletion of Alk2. Our results show that mice lacking Alk2 in the neural crest display multiple craniofacial defects including cleft palate and a hypotrophic mandible. Based on the present results we conclude that signaling via Alk2 receptors is non-redundant and regulates normal development of a restricted set of structures derived from the cranial neural crest.