The long-term goal of this research is to expand our understanding of the biological basis of craniofacial morphogensesis and the underlying causes of craniofacial abnormalities. Craniofacial abnormalities affect hundreds of thousands of children each year resulting in physical, emotional and economic hardships for affected individuals and their families. The causes of these malformations are largely unknown. Mouse models provide an increasingly important resource for identification of genes important in normal and abnormal craniofacial development. We have identified a cellular nucleic acid binding protein (CNBP) null mutant mouse strain with forebrain truncation. Heterozygous mutants survive to birth with various craniofacial abnormalities, including absence of anterior head structures, lower jaw and eyes. We have demonstrated that the expression of CNBP is restricted to the anterior of the early mouse embryos, including the anterior visceral endoderm (AVE), anterior definitive endoderm (ADE) and telencephalon, and showed that some AVE, ADE and telencephalon marker genes are absent in CNBP-/- mutants. Based on our preliminary data, we propose that: CNBP plays an essential role in head formation by regulating the development of AVE, ADE and telencephalon respectively. We will test this hypothesis through three specific aims. First, we will examine the tissue-specific role of CNBP during forebrain development using chimeric embryos technology to characterize the origin of the forebrain defects in CNBP mutant embryos. Mouse chimeras will be generated such that either the extraembryonic or embryonic tissue is CNBP deficient in order to identify in which tissue CNBP acts. In Aim 2, we will characterize the genetic interactions of CNBP with the transcriptional regulator HNF3. CNBP+/- mutants will be crossed with HNF3+/-mutants to generate double heterozygous in order to determine whether these genes interact to begin to identify their role in anterior patterning. Finally, we will generate and characterize CNBP telencephalon tissue-specific targeted disruption mice (CNBPflox/flox/Cre) using Cre/loxP technology and the Foxg1-Cre mouse line, and will examine the role of CNBP in the development of the telencephalon and its derivatives, as well as other head structures. Collectively, these studies will provide insight into the biological and molecular basis of normal craniofacial morphogenesis and associated abnormalities.
