| Seq #268 | Saturday, 12 March 2005 | |||||||
| 8:00 AM-8:45 AM Baltimore Convention Center Ballroom 1, Plenary | ||||||||
| Hedgehog Signaling Network | ||||||||
Sponsored by: none | ||||||||
| Description: In the hedgehog signaling network, mutations result in various phenotypes, including, among others, holoprosencephaly, nevoid basal cell carcinoma syndrome, Pallister-Hall syndrome, Greig cephalopolysyndactyly, Rubinstein-Taybi syndrome, isolated basal cell carcinoma, and medulloblastoma. Active Hedgehog ligand is double-lipid-modified, with a C-terminal cholesterol moiety and an N-terminal palmitate. Transport of active Hedgehog from the signaling cell to the responding cell occurs by three mechanisms: (1) formation of multimeric Hedgehog, which make it soluble; (2) dispatched, which releases the lipid-anchored protein from the signaling cell; and (3) movement across the plasma membrane of the responding cell by Tout-velu-dependent synthesis of heparin sulfate proteoglycan. In the responding cell, active Hedgehog binds to its receptor Patched, which frees Smoothened for downstream signaling. Patched and Smoothened may shuttle oppositely between the plasma membrane and endocytic vesicles in response to active Hedgehog ligand. In downstream signaling, Cubitus interruptus (Gli proteins in vertebrates), Costal 2, Fused, and Suppressor of Fused form a tetrameric complex. Cubitus interruptus is a bifunctional transcription regulator. In the absence of active Hedgehog ligand, a truncated transcriptional repressor is generated that binds target genes and blocks their transcription. In the presence of active Hedgehog ligand, a full-length transcriptional activator binds target genes and up-regulates their transcription. Target genes include Wingless (Wnt gene family in vertebrates), Decapentaplegic (BMPs in vertebrates), and Patched. This session is graciously sponsored by Quintessence Publishing | ||||||||
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Back to the IADR/AADR/CADR 83rd General Session (March 9-12, 2005)