The same enhancer regulates the earliest Emx2 expression in caudal forebrain primordium, subsequent expression in dorsal telencephalon and later expression in the cortical ventricular zone.
We have analyzed Emx2 enhancers to determine how Emx2 functions during forebrain development are regulated. The FB (forebrain) enhancer we identified immediately 3' downstream of the last coding exon is well conserved among tetrapods and unexpectedly directed all the Emx2 expression in forebrain: caudal forebrain primordium at E8.5, dorsal telencephalon at E9.5-E10.5 and the cortical ventricular zone after E12.5. Otx, Tcf, Smad and two unknown transcription factor binding sites were essential to all these activities. The mutant that lacked this enhancer demonstrated that Emx2 expression under the enhancer is solely responsible for diencephalon development. However, in telencephalon, the FB enhancer did not have activities in cortical hem or Cajal-Retzius cells, nor was its activity in the cortex graded. Emx2 expression was greatly reduced, but persisted in the telencephalon of the enhancer mutant, indicating that there exists another enhancer for Emx2 expression unique to mammalian telencephalon.
Suda
Yoko
Y
Laboratory for Vertebrate Body Plan, Center for Developmental Biology, RIKEN Kobe, Chuo-ku, Kobe, Japan.
Kokura
Kenji
K
Kimura
Jun
J
Kajikawa
Eriko
E
Inoue
Fumitaka
F
Aizawa
Shinichi
S
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002540:Cerebral Cortex / Q000196:embryology / Q000378:metabolism; D017124:Conserved Sequence; D004247:DNA / Q000235:genetics / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004742:Enhancer Elements, Genetic; D005260:Female; D018507:Gene Expression Regulation, Developmental; D005865:Gestational Age; D018398:Homeodomain Proteins / Q000235:genetics*; D051379:Mice; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009154:Mutation; D051857:Otx Transcription Factors / Q000378:metabolism; D010641:Phenotype; D011247:Pregnancy; D016548:Prosencephalon / Q000196:embryology* / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D051785:Smad Proteins / Q000378:metabolism; D013045:Species Specificity; D051820:TCF Transcription Factors / Q000378:metabolism; D013687:Telencephalon / Q000196:embryology / Q000378:metabolism; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics*; D014981:Xenopus / Q000235:genetics; D000099260:Empty Spiracles Homeobox Proteins
D004247:DNA; D017931:DNA Primers; D018398:Homeodomain Proteins; D051857:Otx Transcription Factors; D051785:Smad Proteins; D051820:TCF Transcription Factors; D014157:Transcription Factors; D000099260:Empty Spiracles Homeobox Proteins