Analysis of unique genes in neural tube development and closure

Analysis of unique genes in neural tube development and closure.

BSF grant 2007470Final ReportDr. Ohad Birk (Israel), Dr. Heiner Westphal (USA)ABSTRACTWe set out to identify genes that are likely involved in mammalian neurogenesis and neural tube (NT) closure. The underlying assumption was that genes involved in NT closure are likely expressed in open sections of the NT prior to its closure. In contrast, mRNA expression of genes involved in neurogenesis is likely to be turned on after NT closure, when neuronal differentiation ensues. Therefore, we micro-dissected open versus closed sections of NTs of mouse embryos at embryonic days E8.5 and E9.5 and compared mRNA expression arrays of closed and open sections at both time points. Our studies identified many of the known genes involved in tube closure as well as novel molecular candidates for tube closure. Through whole exome sequencing of familial human NT closure defects cases, we are seeking mutations in those genes. For neurogenesis, many known neurogenesis-related genes were identified, corroborating our hypothesis. Moreover, ~25 novel genes were identified as likely involved in neurogenesis. Our whole mount in situ hybridization studies showed that 4 of these genes were expressed specifically in embryonic mouse NT and brain. Moreover, we showed that mRNA expression of human orthologs of two of these genes was significantly enhanced during neuronal differentiation of human ES cells. We knocked down one of these genes in mammalian neuronal cell lines and studied its ortholog in C. elegans; however, no phenotype was evident. We went on to generate knockout mice for these genes, achieving heterozygous null mutants for one of the genes. Their analysis is underway.