Forebrain and midbrain regions are deleted in Otx2-/- mutants due to a defective anterior neuroectoderm specification during gastrulation.
We have replaced part of the mouse homeogene Otx2 coding region with the E. coli lacZ coding sequence, thus creating a null allele of Otx2. By 9.5 dpc, homozygous mutant embryos are characterized by the absence of forebrain and midbrain regions. From the early to midstreak stages, endomesodermal cells expressing lacZ fail to be properly localized anteriorly. In the ectodermal layer, lacZ transcription is progressively extinguished, being barely detectable by the late streak stage. These data suggest that Otx2 expression in endomesoderm and ectoderm is required for anterior neuroectoderm specification. In gastrulating heterozygous embryos, a post-transcriptional repression acts on lacZ transcripts in the ectoderm, but not in the external layer, suggesting that different post-transcriptional mechanisms control Otx2 expression in both layers.
Acampora
D
D
International Institute of Genetics and Biophysics CNR, Naples, Italy.
Mazan
S
S
Lallemand
Y
Y
Avantaggiato
V
V
Maury
M
M
Simeone
A
A
Brûlet
P
P
D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000196:embryology*; D017931:DNA Primers / Q000235:genetics; D004475:Ectoderm / Q000502:physiology; D004627:Embryonic Induction / Q000502:physiology*; D005775:Gastrula / Q000502:physiology*; D005801:Genes, Homeobox; D018398:Homeodomain Proteins; D017403:In Situ Hybridization; D007763:Lac Operon; D008636:Mesencephalon / Q000196:embryology; D051379:Mice; D008817:Mice, Mutant Strains; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000235:genetics*; D051857:Otx Transcription Factors; D010641:Phenotype; D016548:Prosencephalon / Q000196:embryology; D015534:Trans-Activators / Q000235:genetics*
D017931:DNA Primers; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D051857:Otx Transcription Factors; C497660:Otx2 protein, mouse; D015534:Trans-Activators