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Dev Cell April 1, 2009; 16 (4): 576-87.

Integration of telencephalic Wnt and hedgehog signaling center activities by Foxg1.

Danesin C , Peres JN , Johansson M , Snowden V , Cording A , Papalopulu N , Houart C .

The forebrain is patterned along the dorsoventral (DV) axis by Sonic Hedgehog (Shh). However, previous studies have suggested the presence of an Shh-independent mechanism. Our study identifies Wnt/beta-catenin-activated from the telencephalic roof-as an Shh-independent pathway that is essential for telencephalic pallial (dorsal) specification during neurulation. We demonstrate that the transcription factor Foxg1 coordinates the activity of two signaling centers: Foxg1 is a key downstream effector of the Shh pathway during induction of subpallial (ventral) identity, and it inhibits Wnt/beta-catenin signaling through direct transcriptional repression of Wnt ligands. This inhibition restricts the dorsal Wnt signaling center to the roof plate and consequently limits pallial identities. Concomitantly to these roles, Foxg1 controls the formation of the compartment boundary between telencephalon and basal diencephalon. Altogether, these findings identify a key direct target of Foxg1, and uncover a simple molecular mechanism by which Foxg1 integrates two opposing signaling centers.

PubMed ID: 19386266
Article link: Dev Cell
Grant support: [+]

Species referenced: Xenopus
Genes referenced: dlx2 elavl3 foxg1 isl1 lef1 lhx5 mst1 myod1 shh tbr1 wnt8b

Article Images: [+] show captions