title: EMG1 is essential for mouse pre-implantation embryo development.
abstract: BACKGROUND
  Essential for mitotic growth 1 (EMG1) is a highly conserved nucleolar protein identified in yeast to have a critical function in ribosome biogenesis. A mutation in the human EMG1 homolog causes Bowen-Conradi syndrome (BCS), a developmental disorder characterized by severe growth failure and psychomotor retardation leading to death in early childhood. To begin to understand the role of EMG1 in mammalian development, and how its deficiency could lead to Bowen-Conradi syndrome, we have used mouse as a model. The expression of Emg1 during mouse development was examined and mice carrying a null mutation for Emg1 were generated and characterized.
  
  
  RESULTS
  Our studies indicated that Emg1 is broadly expressed during early mouse embryonic development. However, in late embryonic stages and during postnatal development, Emg1 exhibited specific expression patterns. To assess a developmental role for EMG1 in vivo, we exploited a mouse gene-targeting approach. Loss of EMG1 function in mice arrested embryonic development prior to the blastocyst stage. The arrested Emg1-/- embryos exhibited defects in early cell lineage-specification as well as in nucleologenesis. Further, loss of p53, which has been shown to rescue some phenotypes resulting from defects in ribosome biogenesis, failed to rescue the Emg1-/- pre-implantation lethality.
  
  
  CONCLUSIONS
  Our data demonstrate that Emg1 is highly expressed during mouse embryonic development, and essential for mouse pre-implantation development. The absolute requirement for EMG1 in early embryonic development is consistent with its essential role in yeast. Further, our findings also lend support to the previous study that showed Bowen-Conradi syndrome results from a partial EMG1 deficiency. A complete deficiency would not be expected to be compatible with a live birth.
authors.affiliation: Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Canada.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Wu
authors.forename: Sumit
authors.initials: S
authors.lastname: Sandhu
authors.forename: Nehal
authors.initials: N
authors.lastname: Patel
authors.forename: Barbara
authors.initials: B
authors.lastname: Triggs-Raine
authors.forename: Hao
authors.initials: H
authors.lastname: Ding
mesh_terms: D000818:Animals; D019070:Cell Lineage; D004622:Embryo, Mammalian / Q000033:anatomy & histology / Q000502:physiology*; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D005317:Fetal Growth Retardation / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D005838:Genotype; D006801:Humans; D008297:Male; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011596:Psychomotor Disorders / Q000235:genetics / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
chemical_list: C556162:EMG1 protein, mouse; D009687:Nuclear Proteins; D016159:Tumor Suppressor Protein p53; D008780:Methyltransferases