Structural insights into the role of the Smoothened cysteine-rich domain in Hedgehog signalling

Rana, Rajashree; Carroll, Candace E.; Lee, Ho‐Jin; Bao, Jie; Marada, Suresh; Grace, Christy R.; Guibao, Cristina D.; Ogden, Stacey K.; Zheng, Jie

doi:10.1038/ncomms3965

Cited by 74 publications

(72 citation statements)

References 56 publications

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“…In vertebrates, 7-keto-27-OHC (Table 1) functions as an agonist at the SMO CRD 16 . Although Drosophila Smo does not respond to 20(S)-OHC 73,74 , the glucocorticoid budesonide ( Table 1) binds both Drosophila and human SMO CRDs using NMR chemical shift perturbations and can inhibit SMO activity 76 . The precise role of the SMO CRD in endogenous Hedgehog signaling is a key question.…”

Section: Smo Regulation Through Its Crdmentioning

confidence: 99%

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Regulation of the oncoprotein Smoothened by small molecules

Sharpe

Wang²,

Hannoush³

et al. 2015

Nat Chem Biol

108

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The Hedgehog pathway is critical for animal development and has been implicated in multiple human malignancies. Despite great interest in targeting the pathway pharmacologically, many of the principles underlying the signal transduction cascade remain poorly understood. Hedgehog ligands are recognized by a unique receptor system that features the transporter-like protein Patched and the G protein-coupled receptor (GPCR)-like Smoothened (SMO). The biochemical interaction between these transmembrane proteins is the subject of intensive efforts. Recent structural and functional studies have provided great insight into the small-molecule regulation of SMO through identification of two distinct ligand-binding sites. In this Perspective, we review these recent findings and relate them to potential mechanisms for the endogenous regulation of SMO.

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Section: Smo Regulation Through Its Crdmentioning

confidence: 99%

“…7a,25-OHC neither competes with 20(S)OHC for binding to SMO nor activates Hh signaling 16 . Multiple small molecules are capable of modulating the SMO CRD 75,76 . In vertebrates, 7-keto-27-OHC (Table 1) functions as an agonist at the SMO CRD 16 .…”

Section: Smo Regulation Through Its Crdmentioning

confidence: 99%

Regulation of the oncoprotein Smoothened by small molecules

Sharpe

Wang²,

Hannoush³

et al. 2015

Nat Chem Biol

108

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“…Curiously, the Drosophila Smo CRD does not bind to 20(S)-OHC (63), but it and human Smo CRD were recently shown to bind to the glucocorticoid budesonide (Fig. 4B), suggesting that sterol binding by the Smo CRD may be a conserved feature of Hh signaling (69). Glucocorticoids represent an interesting class of Smo modulators as both inhibitors and activators of the Hh pathway have been found with glucocorticoid scaffolds, and budesonide inhibits WT Smo, SmoD473H, and SmoM2 equally well, ideal features for a Smo-targeting drug (70).…”

Section: Smoothened: Cysteine-rich Domainmentioning

confidence: 99%

Smoothened Goes Molecular: New Pieces in the Hedgehog Signaling Puzzle

McCabe¹,

Leahy

2015

Journal of Biological Chemistry

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A general aim of studies of signal transduction is to identify mediators of specific signals, order them into pathways, and understand the nature of interactions between individual components and how these interactions alter pathway behavior. Despite years of intensive study and its central importance to animal development and human health, our understanding of the Hedgehog (Hh) signaling pathway remains riddled with gaps, question marks, assumptions, and poorly understood connections. In particular, understanding how interactions between Hh and Patched (Ptc), a 12-pass integral membrane protein, lead to modulation of the function of Smoothened (Smo), a 7-pass integral membrane protein, has defied standard biochemical characterization. Recent structural and biochemical characterizations of Smoothened domains have begun to unlock this riddle, however, and lay the groundwork for improved cancer therapies. Members of the Hedgehog (Hh)3 family of secreted signaling proteins are present in most metazoans and owe their name to the effects that loss of Hh function has on Drosophila embryos, which lose their normal segmented pattern and develop a uniform coat of bristles reminiscent of the coats of hedgehogs (1). As presaged by this phenotype, Hh proteins mediate essential tissue patterning events during many stages of animal development (2), and abnormal Hh function is associated with birth defects and cancer (3). Hh proteins are also involved in tissue maintenance and wound repair in adult animals (4). Hh proteins achieve their patterning effects by functioning as classical morphogens (5). That is, Hh proteins form gradients of decreasing concentration from sites of secretion and induce concentration-dependent differentiation of distinct cell types (6, 7). As befits a morphogen, Hh expression, release, diffusion, and signal reception are tightly regulated by multiple factors (8).Classical and modern genetic techniques have identified several cell-surface proteins and glycans involved in receiving or modifying Hh signals (9). The core components of this process, conserved in all organisms known to have active Hh signaling, are Patched (Ptc) and Smoothened (Smo) (Fig. 1) (10 -13). Ptc functions upstream of Smo and has been genetically and biochemically defined as a primary component of the Hh receptor (14,15). Ptc is a 12-pass integral membrane protein with distant homology to bacterial resistance-nodulation-cell division (RND) transporters (16,17). Transmembrane helices 2-6 of Ptc are also homologous to sterol-sensing domains, which are found in diverse integral membrane proteins and regulate activity in response to levels of free cellular sterols (18). Smo is a member of the Frizzled family (class F) of G-protein coupled receptors (GPCRs) (19), and contains an N-terminal, ϳ14-kDa extracellular cysteine-rich domain (CRD) connected via a linker to 7 membrane-spanning helices (7TM) and an extended (ϳ200 amino acids, human; ϳ450 amino acids, Drosophila) C-terminal tail.Hh signaling responses are modulated by additional ce...

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“…To test this hypothesis and gain structural and functional understanding of this domain, we determined the structure of the Drosophila Smo CRD by solution NMR spectroscopy. Our findings show that Smo CRD is a structured domain predominated by alpha helical secondary structures stabilized by disulfide bonds and maintains the tertiary fold similar to the FzD CRD [147]. The residues highlighted in yellow correspond to the "site 1" and the residues highlighted in green correspond to the "site 2" binding site in FzD-Wnt interaction.…”

Section: Introductionmentioning

confidence: 99%

“…To test this hypothesis we analyzed the interaction between the glucocorticoid Bud and the Drosophila and human Smo CRD by NMR CSP experiments [143,155]. Our results demonstrate that Bud binds to both Drosophila and human Smo CRD, albeit with different binding affinities [147]. † Furthermore, we generated the modelled structure of Drosophila Smo CRD in complex with the inhibitory glucocorticoid Bud, which showed that Bud docks in a conserved hydrophobic pocket in Smo CRD.…”

Section: Introductionmentioning

confidence: 99%

Novel Insights into the Role of the Smoothened Cysteine Rich Domain in Hedgehog Signalling

Rana¹

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Structural insights into the role of the Smoothened cysteine-rich domain in Hedgehog signalling

Cited by 74 publications

References 56 publications

Regulation of the oncoprotein Smoothened by small molecules

Regulation of the oncoprotein Smoothened by small molecules

Smoothened Goes Molecular: New Pieces in the Hedgehog Signaling Puzzle

Novel Insights into the Role of the Smoothened Cysteine Rich Domain in Hedgehog Signalling

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