Regulation of neural crest cell proliferation, differentiation and death in normal development and diseases

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We have used chromatin immunoprecipitation to screen for target genes for Ncx (Tlx2, Enx, Hox11 L1). This screen led to the identification of novel KRAB zinc finger protein termed Nczf. Nczf is co-expressed with Ncx in enteric neurons. Promoter region of Nczf gene contains 4 consensus sequences for Ncx binding motifs. The luciferase reporter gene analysis with various amount of Ncx expression vector showed dose dependent increase of the Nczf promoter activity. The Nczf mRNA expression was analyzed in mouse development. The mRNA was detected in 7.5 days of embryogenesis (E7.5) and was maximal at E9.5 by RT-PCR. The expression was further examined in various tissues from embryos and newborns by in situ hybridization. It was detected throughout the body between E7.5 and E9.5. High level of expression was detected in neuroepithelium at E10.5, and subsequently in the ventricular zone of central nervous system from E12.5. Strong signal was also detected in external granular layer of the developing cerebellum at P7. Nczf mRNA was also expressed in postmitotic neurons of the cranial ganglia and dorsal root ganglia, and pachytene stage spermatocytes at first meiotic cell division in spermatogenesis. These results suggest that Nczf plays a crucial role in rapid cell proliferation at early organogenesis as well as neuronal cell differentiation and meiotic cell division in spermatogenesis.In order to elucidate the function of Nczf, we generated Nczf deficient (KO) mice by homologous recombination. Nczf KO mice were embryonic lethal and died around E8.5-9.5. Cell numbers are reduced and many apoptotic cells were observed. Organogenesis took place normally but embryos could not turn their body as normally occurred in E8.5. We are now investigating the function of Nczf using these KO mice and also creating conditional KO mice using Cre-LoaP system.