Multiple N-cadherin enhancers identified by systematic functional screening indicate its Group B1 SOX-dependent regulation in neural and placodal development.
Neural plate and sensory placodes share the expression of N-cadherin and Group B1 Sox genes, represented by Sox2. A 219-kb region of the chicken genome centered by the N-cadherin gene was scanned for neural and placodal enhancers. Random subfragments of 4.5 kb average length were prepared and inserted into tkEGFP reporter vector to construct a library with threefold coverage of the region. Each clone was then transfected into N-cadherin-positive (lens, retina and forebrain) or -negative embryonic cells, or electroporated into early chicken embryos to examine enhancer activity. Enhancers 1-4 active in the CNS/placode derivatives and non-specific Enhancer 5 were identified by transfection, while electroporation of early embryos confirmed enhancers 2-4 as having activity in the early CNS and/or sensory placodes but with unique spatiotemporal specificities. Enhancers 2-4 are dependent on SOX-binding sites, and misexpression of Group B1 Sox genes in the head ectoderm caused ectopic development of placodes expressing N-cadherin, indicating the involvement of Group B1 Sox functions in N-cadherin regulation. Enhancers 1, 2 and 4 correspond to sequence blocks conserved between the chicken and mammalian genomes, but enhancers 3 and 5 are unique to the chicken.
Matsumata
Miho
M
Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
Uchikawa
Masanori
M
Kamachi
Yusuke
Y
Kondoh
Hisato
H
D000818:Animals; D001665:Binding Sites; D015820:Cadherins / Q000235:genetics*; D002642:Chick Embryo; D002645:Chickens; D004268:DNA-Binding Proteins / Q000235:genetics*; D004475:Ectoderm / Q000166:cytology; D004742:Enhancer Elements, Genetic; D024002:HMGB Proteins / Q000235:genetics*; D007908:Lens, Crystalline / Q000196:embryology; D016548:Prosencephalon / Q000196:embryology / Q000254:growth & development*; D012160:Retina / Q000196:embryology; D055748:SOXB1 Transcription Factors; D014157:Transcription Factors / Q000235:genetics*; D014162:Transfection
D015820:Cadherins; D004268:DNA-Binding Proteins; D024002:HMGB Proteins; D055748:SOXB1 Transcription Factors; D014157:Transcription Factors