Contribution of cranial neural crest cells to mouse skull development.

The mammalian skull vault is a highly regulated structure that evolutionally protects brain growth during vertebrate development. It consists of several membrane bones with different tissue origins (e.g. neural crest-derived frontal bone and mesoderm-derived parietal bone). Although membrane bones are formed through intramembranous ossification, the neural crest-derived frontal bone has superior capabilities for osteoblast activities and bone regeneration via TGF, BMP, Wnt, and FGF signaling pathways. Neural crest (NC) cells are multipotent, and once induced, will follow specific paths to migrate to different locations of the body where they give rise to a diverse array of cell types and tissues. Recent studies using genetic mouse models have greatly advanced our knowledge of NC cell induction, proliferation, migration and differentiation. Perturbations or disruptions of neural crest patterning lead to severe developmental defects or diseases. This review summarizes recent discoveries including novel functions of genes or signaling molecules that are capable of governing developmental processes of neural crest patterning, which may function as a gene regulatory network in controlling skull development. The proposed regulatory network will be important to understand how the signaling pathways and genes converge to regulate osteoblast activities and bone formation, which will be beneficial for the potential identification of molecular targets to prevent or alleviate human diseases or disorders involving defective neural crest development.