The Sonic Hedgehog Receptor Patched Associates with Caveolin-1 in Cholesterol-rich Microdomains of the Plasma Membrane

• DOI: 10.1074/jbc.m010832200
• Publication Date: 2002-07-26T15:09:24Z
• Authors: Heidi E. Karpen; John T. Bukowski; Thomas Hughes; Jean-Philíppe Gra...; William C. Sessa; Mae R. Gailani
• Keywords: Smoothened; Patched; Lipid raft; Caveolin

The Hedgehog signaling pathway is involved in early embryonic patterning as well cancer; however, little known about the subcellular localization of receptor complex Patched and Smoothened. Since Hh has been found lipid rafts Drosophila, we hypothesized that Smoothened might also be these cholesterol-rich microdomains. In this study, demonstrate both are caveolin-1-enriched/raft Immunoprecipitation studies show specifically interacts with caveolin-1, whereas does not. Fractionation caveolin-1 can co-isolated from buoyant density fractions represent caveolae/raft microdomains co-localize by confocal microscopy. GlutathioneS-transferase fusion protein experiments interaction between involves scaffolding domain a consensus binding site. Immunocytochemistry data fractionation seems to required for transport membrane. Depletion plasmalemmal cholesterol influences distribution caveolin-enriched/raft These suggest may integral sequestering caveolin-enriched microdomains, which act scaffold interactions protein. green fluorescent phosphate-buffered saline endoplasmic reticulum glutathione S-transferase methyl-β-cyclodextrin pathway, first described inDrosophila conserved vertebrates, fundamental many structures, including neural tube, axial skeleton, limbs, lungs. Sonic (Shh), most studied three vertebrate homologs ofDrosophila Hedgehog, secreted acts on target cells increase transcription several genes, members Wnt transforming growth factor-β families, its Patched. (Ptc) predicted encode large transmembrane negative regulator pathway. It associates second protein, (Smo), positive Prior genetic biochemical indicate two proteins form an unusual at membrane inactive absence Shh ligand. Once binds Ptc, relieves inhibition Smo (by unknown mechanisms) allows transduction signal. 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