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Title: Cellular Cholesterol Directly Activates Smoothened in Hedgehog Signaling

Abstract

In vertebrates, sterols are necessary for Hedgehog signaling, a pathway critical in embryogenesis and cancer. Sterols activate the membrane protein Smoothened by binding its extracellular, cysteine-rich domain (CRD). Major unanswered questions concern the nature of the endogenous, activating sterol and the mechanism by which it regulates Smoothened. We report crystal structures of CRD complexed with sterols and alone, revealing that sterols induce a dramatic conformational change of the binding site, which is sufficient for Smoothened activation and is unique among CRD-containing receptors. We demonstrate that Hedgehog signaling requires sterol binding to Smoothened and define key residues for sterol recognition and activity. We also show that cholesterol itself binds and activates Smoothened. Furthermore, the effect of oxysterols is abolished in Smoothened mutants that retain activation by cholesterol and Hedgehog. We propose that the endogenous Smoothened activator is cholesterol, not oxysterols, and that vertebrate Hedgehog signaling controls Smoothened by regulating its access to cholesterol.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); National Institutes of Health (NIH)
OSTI Identifier:
1336817
DOE Contract Number:
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cell; Journal Volume: 166; Journal Issue: 5
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES

Citation Formats

Huang, Pengxiang, Nedelcu, Daniel, Watanabe, Miyako, Jao, Cindy, Kim, Youngchang, Liu, Jing, and Salic, Adrian. Cellular Cholesterol Directly Activates Smoothened in Hedgehog Signaling. United States: N. p., 2016. Web. doi:10.1016/j.cell.2016.08.003.
Huang, Pengxiang, Nedelcu, Daniel, Watanabe, Miyako, Jao, Cindy, Kim, Youngchang, Liu, Jing, & Salic, Adrian. Cellular Cholesterol Directly Activates Smoothened in Hedgehog Signaling. United States. doi:10.1016/j.cell.2016.08.003.
Huang, Pengxiang, Nedelcu, Daniel, Watanabe, Miyako, Jao, Cindy, Kim, Youngchang, Liu, Jing, and Salic, Adrian. Mon . "Cellular Cholesterol Directly Activates Smoothened in Hedgehog Signaling". United States. doi:10.1016/j.cell.2016.08.003.
@article{osti_1336817,
title = {Cellular Cholesterol Directly Activates Smoothened in Hedgehog Signaling},
author = {Huang, Pengxiang and Nedelcu, Daniel and Watanabe, Miyako and Jao, Cindy and Kim, Youngchang and Liu, Jing and Salic, Adrian},
abstractNote = {In vertebrates, sterols are necessary for Hedgehog signaling, a pathway critical in embryogenesis and cancer. Sterols activate the membrane protein Smoothened by binding its extracellular, cysteine-rich domain (CRD). Major unanswered questions concern the nature of the endogenous, activating sterol and the mechanism by which it regulates Smoothened. We report crystal structures of CRD complexed with sterols and alone, revealing that sterols induce a dramatic conformational change of the binding site, which is sufficient for Smoothened activation and is unique among CRD-containing receptors. We demonstrate that Hedgehog signaling requires sterol binding to Smoothened and define key residues for sterol recognition and activity. We also show that cholesterol itself binds and activates Smoothened. Furthermore, the effect of oxysterols is abolished in Smoothened mutants that retain activation by cholesterol and Hedgehog. We propose that the endogenous Smoothened activator is cholesterol, not oxysterols, and that vertebrate Hedgehog signaling controls Smoothened by regulating its access to cholesterol.},
doi = {10.1016/j.cell.2016.08.003},
journal = {Cell},
number = 5,
volume = 166,
place = {United States},
year = {Mon Aug 01 00:00:00 EDT 2016},
month = {Mon Aug 01 00:00:00 EDT 2016}
}