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XB-ART-2788
Development December 1, 2004; 131 (23): 5871-81.

Six1 promotes a placodal fate within the lateral neurogenic ectoderm by functioning as both a transcriptional activator and repressor.

Brugmann SA , Pandur PD , Kenyon KL , Pignoni F , Moody SA .


Abstract
Cranial placodes, which give rise to sensory organs in the vertebrate head, are important embryonic structures whose development has not been well studied because of their transient nature and paucity of molecular markers. We have used markers of pre-placodal ectoderm (PPE) (six1, eya1) to determine that gradients of both neural inducers and anteroposterior signals are necessary to induce and appropriately position the PPE. Overexpression of six1 expands the PPE at the expense of neural crest and epidermis, whereas knock-down of Six1 results in reduction of the PPE domain and expansion of the neural plate, neural crest and epidermis. Using expression of activator and repressor constructs of six1 or co-expression of wild-type six1 with activating or repressing co-factors (eya1 and groucho, respectively), we demonstrate that Six1 inhibits neural crest and epidermal genes via transcriptional repression and enhances PPE genes via transcriptional activation. Ectopic expression of neural plate, neural crest and epidermal genes in the PPE demonstrates that these factors mutually influence each other to establish the appropriate boundaries between these ectodermal domains.

PubMed ID: 15525662
Article link: Development
Grant support: [+]
Genes referenced: bmp4 chrd.1 dlx5 dlx6 eya1 foxd3 frzb krt12.4 myc nog six1 sox11 sox2 wnt8a zic2
Morpholinos: six1 MO1 six1 MO2


Article Images: [+] show captions


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