CDEBP, a site-specific DNA-binding protein of the 'APP-like' family, is required during the early development of the mouse.

A murine protein, termed CDEBP, was previously shown to bind the double-stranded DNA motif GTCACATG, identical to the yeast centromeric element CDEI. The cDNA sequence showed three domains with extensive similarities to the amyloid beta precursor protein (APP). The protein is homologous over its entire length to the human protein designated APPH. In situ immunofluorescence assays using antibodies raised against distinct parts of CDEBP detected discrete sites of accumulation inside the interphase nucleus, and the bulk of the protein was not associated with mitotic chromosomes. One of the complexes with double-stranded CDEI oligonucleotides detected by gel shift assay was not present when the protein had been selectively removed from nuclear extracts by immunoprecipitation. We reported previously that microinjection into one-cell mouse embryos of DNA fragments including the CDEI sequence results in an early arrest of development with abnormal nuclei containing variable amounts of DNA. The same characteristic figures were observed when embryos were treated with antisense oligonucleotides complementary to parts of the CDEBP coding region. Complexes between the CDEBP protein and CDEI sites in the mouse genome thus appear to play a critical role in the replication/segregation of the embryonic genome.