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Walker MF, Zhang J, Steiner W, Ku PI, Zhu JF, Michaelson Z, Yen YC, Lee A, Long AB, Casey MJ, Poddar A, Nelson IB, Arveseth CD, Nagel F, Clough R, LaPotin S, Kwan KM, Schulz S, Stewart RA, Tesmer JJG, Caspary T, Subramanian R, Ge X, Myers BR. GRK2 kinases in the primary cilium initiate SMOOTHENED-PKA signaling in the Hedgehog cascade. PLoS Biol 2024; 22:e3002685. [PMID: 39138140 PMCID: PMC11322411 DOI: 10.1371/journal.pbio.3002685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 05/21/2024] [Indexed: 08/15/2024] Open
Abstract
During Hedgehog (Hh) signal transduction in development and disease, the atypical G protein-coupled receptor (GPCR) SMOOTHENED (SMO) communicates with GLI transcription factors by binding the protein kinase A catalytic subunit (PKA-C) and physically blocking its enzymatic activity. Here, we show that GPCR kinase 2 (GRK2) orchestrates this process during endogenous mouse and zebrafish Hh pathway activation in the primary cilium. Upon SMO activation, GRK2 rapidly relocalizes from the ciliary base to the shaft, triggering SMO phosphorylation and PKA-C interaction. Reconstitution studies reveal that GRK2 phosphorylation enables active SMO to bind PKA-C directly. Lastly, the SMO-GRK2-PKA pathway underlies Hh signal transduction in a range of cellular and in vivo models. Thus, GRK2 phosphorylation of ciliary SMO and the ensuing PKA-C binding and inactivation are critical initiating events for the intracellular steps in Hh signaling. More broadly, our study suggests an expanded role for GRKs in enabling direct GPCR interactions with diverse intracellular effectors.
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Affiliation(s)
- Madison F. Walker
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Jingyi Zhang
- Department of Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, California, United States of America
| | - William Steiner
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Pei-I Ku
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Ju-Fen Zhu
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Zachary Michaelson
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Yu-Chen Yen
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Annabel Lee
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Alyssa B. Long
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Mattie J. Casey
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Abhishek Poddar
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Isaac B. Nelson
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Corvin D. Arveseth
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | | | - Ryan Clough
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Sarah LaPotin
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Kristen M. Kwan
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Stefan Schulz
- 7TM Antibodies GmbH, Jena, Germany
- Institute of Pharmacology and Toxicology, University Hospital Jena, Jena, Germany
| | - Rodney A. Stewart
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - John J. G. Tesmer
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, United States of America
| | - Tamara Caspary
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Radhika Subramanian
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Xuecai Ge
- Department of Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, California, United States of America
| | - Benjamin R. Myers
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
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2
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Hilgendorf KI, Myers BR, Reiter JF. Emerging mechanistic understanding of cilia function in cellular signalling. Nat Rev Mol Cell Biol 2024; 25:555-573. [PMID: 38366037 PMCID: PMC11199107 DOI: 10.1038/s41580-023-00698-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/21/2023] [Indexed: 02/18/2024]
Abstract
Primary cilia are solitary, immotile sensory organelles present on most cells in the body that participate broadly in human health, physiology and disease. Cilia generate a unique environment for signal transduction with tight control of protein, lipid and second messenger concentrations within a relatively small compartment, enabling reception, transmission and integration of biological information. In this Review, we discuss how cilia function as signalling hubs in cell-cell communication using three signalling pathways as examples: ciliary G-protein-coupled receptors (GPCRs), the Hedgehog (Hh) pathway and polycystin ion channels. We review how defects in these ciliary signalling pathways lead to a heterogeneous group of conditions known as 'ciliopathies', including metabolic syndromes, birth defects and polycystic kidney disease. Emerging understanding of these pathways' transduction mechanisms reveals common themes between these cilia-based signalling pathways that may apply to other pathways as well. These mechanistic insights reveal how cilia orchestrate normal and pathophysiological signalling outputs broadly throughout human biology.
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Affiliation(s)
- Keren I Hilgendorf
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA.
| | - Benjamin R Myers
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA.
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT, USA.
- Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, UT, USA.
| | - Jeremy F Reiter
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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3
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Del Giovane A, Russo M, Tirou L, Faure H, Ruat M, Balestri S, Sposato C, Basoli F, Rainer A, Kassoussi A, Traiffort E, Ragnini-Wilson A. Smoothened/AMP-Activated Protein Kinase Signaling in Oligodendroglial Cell Maturation. Front Cell Neurosci 2022; 15:801704. [PMID: 35082605 PMCID: PMC8784884 DOI: 10.3389/fncel.2021.801704] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 11/29/2021] [Indexed: 12/14/2022] Open
Abstract
The regeneration of myelin is known to restore axonal conduction velocity after a demyelinating event. Remyelination failure in the central nervous system contributes to the severity and progression of demyelinating diseases such as multiple sclerosis. Remyelination is controlled by many signaling pathways, such as the Sonic hedgehog (Shh) pathway, as shown by the canonical activation of its key effector Smoothened (Smo), which increases the proliferation of oligodendrocyte precursor cells via the upregulation of the transcription factor Gli1. On the other hand, the inhibition of Gli1 was also found to promote the recruitment of a subset of adult neural stem cells and their subsequent differentiation into oligodendrocytes. Since Smo is also able to transduce Shh signals via various non-canonical pathways such as the blockade of Gli1, we addressed the potential of non-canonical Smo signaling to contribute to oligodendroglial cell maturation in myelinating cells using the non-canonical Smo agonist GSA-10, which downregulates Gli1. Using the Oli-neuM cell line, we show that GSA-10 promotes Gli2 upregulation, MBP and MAL/OPALIN expression via Smo/AMP-activated Protein Kinase (AMPK) signaling, and efficiently increases the number of axonal contact/ensheathment for each oligodendroglial cell. Moreover, GSA-10 promotes the recruitment and differentiation of oligodendroglial progenitors into the demyelinated corpus callosum in vivo. Altogether, our data indicate that non-canonical signaling involving Smo/AMPK modulation and Gli1 downregulation promotes oligodendroglia maturation until axon engagement. Thus, GSA-10, by activation of this signaling pathway, represents a novel potential remyelinating agent.
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Affiliation(s)
- Alice Del Giovane
- Department of Biology, University of Rome “Tor Vergata”, Rome, Italy
| | - Mariagiovanna Russo
- CNRS, Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, Saclay, France
| | - Linda Tirou
- CNRS, Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, Saclay, France
| | - Hélène Faure
- CNRS, Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, Saclay, France
| | - Martial Ruat
- CNRS, Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, Saclay, France
| | - Sonia Balestri
- Department of Biology, University of Rome “Tor Vergata”, Rome, Italy
| | - Carola Sposato
- Department of Biology, University of Rome “Tor Vergata”, Rome, Italy
| | - Francesco Basoli
- Department of Engineering, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Alberto Rainer
- Department of Engineering, Università Campus Bio-Medico di Roma, Rome, Italy
- Institute of Nanotechnology (NANOTEC), National Research Council, Lecce, Italy
| | | | - Elisabeth Traiffort
- INSERM, U1195, Université Paris-Saclay, Le Kremlin-Bicêtre, France
- *Correspondence: Elisabeth Traiffort,
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4
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Rapid, Direct SMOOTHENED Activity Assays in Live Cells Using cAMP-Based Conformational Sensors. Methods Mol Biol 2021. [PMID: 34562252 DOI: 10.1007/978-1-0716-1701-4_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Communication between PATCHED1 (PTCH1) and SMOOTHENED (SMO) is fundamental to Hedgehog (Hh) signal transduction in development and disease. We describe a real-time cell-based SMO functional assay based on SMO activity-dependent changes in cellular cAMP concentrations. This assay is capable of detecting changes in SMO conformation within minutes of PTCH1 inactivation by Hh ligands. As a result, it expands the range of experimental perturbations that can be used to dissect PTCH1-SMO communication, enabling a deeper mechanistic understanding of a longstanding mystery in Hh signal transduction.
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5
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Studies of SMOOTHENED Activation in Cell-Free and Reconstituted Systems. Methods Mol Biol 2021. [PMID: 34562251 DOI: 10.1007/978-1-0716-1701-4_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Much of our current understanding of Hedgehog signal transduction derives from studies involving intact cells and organisms. Here we describe the use of cell-free and reconstituted systems to study a key step in Hedgehog signal transduction: the activation of SMOOTHENED by membrane lipids. These methods can be adapted to study other steps in Hedgehog signal transduction, particularly those that occur at the membrane.
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6
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Turku A, Schihada H, Kozielewicz P, Bowin CF, Schulte G. Residue 6.43 defines receptor function in class F GPCRs. Nat Commun 2021; 12:3919. [PMID: 34168128 PMCID: PMC8225760 DOI: 10.1038/s41467-021-24004-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 05/28/2021] [Indexed: 12/15/2022] Open
Abstract
The class Frizzled of G protein-coupled receptors (GPCRs), consisting of ten Frizzled (FZD1-10) subtypes and Smoothened (SMO), remains one of the most enigmatic GPCR families. While SMO relies on cholesterol binding to the 7TM core of the receptor to activate downstream signaling, underlying details of receptor activation remain obscure for FZDs. Here, we aimed to investigate the activation mechanisms of class F receptors utilizing a computational biology approach and mutational analysis of receptor function in combination with ligand binding and downstream signaling assays in living cells. Our results indicate that FZDs differ substantially from SMO in receptor activation-associated conformational changes. SMO manifests a preference for a straight TM6 in both ligand binding and functional readouts. Similar to the majority of GPCRs, FZDs present with a kinked TM6 upon activation owing to the presence of residue P6.43. Functional comparison of FZD and FZD P6.43F mutants in different assay formats monitoring ligand binding, G protein activation, DVL2 recruitment and TOPflash activity, however, underlines further the functional diversity among FZDs and not only between FZDs and SMO.
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Affiliation(s)
- Ainoleena Turku
- Karolinska Institutet, Department of Physiology & Pharmacology, Sec. Receptor Biology & Signaling, Biomedicum 6D, Stockholm, Sweden
- Orion Pharma R&D, Espoo, Finland
| | - Hannes Schihada
- Karolinska Institutet, Department of Physiology & Pharmacology, Sec. Receptor Biology & Signaling, Biomedicum 6D, Stockholm, Sweden
| | - Pawel Kozielewicz
- Karolinska Institutet, Department of Physiology & Pharmacology, Sec. Receptor Biology & Signaling, Biomedicum 6D, Stockholm, Sweden
| | - Carl-Fredrik Bowin
- Karolinska Institutet, Department of Physiology & Pharmacology, Sec. Receptor Biology & Signaling, Biomedicum 6D, Stockholm, Sweden
| | - Gunnar Schulte
- Karolinska Institutet, Department of Physiology & Pharmacology, Sec. Receptor Biology & Signaling, Biomedicum 6D, Stockholm, Sweden.
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7
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Arveseth CD, Happ JT, Hedeen DS, Zhu JF, Capener JL, Klatt Shaw D, Deshpande I, Liang J, Xu J, Stubben SL, Nelson IB, Walker MF, Kawakami K, Inoue A, Krogan NJ, Grunwald DJ, Hüttenhain R, Manglik A, Myers BR. Smoothened transduces Hedgehog signals via activity-dependent sequestration of PKA catalytic subunits. PLoS Biol 2021; 19:e3001191. [PMID: 33886552 PMCID: PMC8096101 DOI: 10.1371/journal.pbio.3001191] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 05/04/2021] [Accepted: 03/16/2021] [Indexed: 12/13/2022] Open
Abstract
The Hedgehog (Hh) pathway is essential for organ development, homeostasis, and regeneration. Dysfunction of this cascade drives several cancers. To control expression of pathway target genes, the G protein-coupled receptor (GPCR) Smoothened (SMO) activates glioma-associated (GLI) transcription factors via an unknown mechanism. Here, we show that, rather than conforming to traditional GPCR signaling paradigms, SMO activates GLI by binding and sequestering protein kinase A (PKA) catalytic subunits at the membrane. This sequestration, triggered by GPCR kinase (GRK)-mediated phosphorylation of SMO intracellular domains, prevents PKA from phosphorylating soluble substrates, releasing GLI from PKA-mediated inhibition. Our work provides a mechanism directly linking Hh signal transduction at the membrane to GLI transcription in the nucleus. This process is more fundamentally similar between species than prevailing hypotheses suggest. The mechanism described here may apply broadly to other GPCR- and PKA-containing cascades in diverse areas of biology.
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Affiliation(s)
- Corvin D. Arveseth
- Department of Oncological Sciences, Department of Biochemistry, Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - John T. Happ
- Department of Oncological Sciences, Department of Biochemistry, Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Danielle S. Hedeen
- Department of Oncological Sciences, Department of Biochemistry, Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Ju-Fen Zhu
- Department of Oncological Sciences, Department of Biochemistry, Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Jacob L. Capener
- Department of Oncological Sciences, Department of Biochemistry, Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Dana Klatt Shaw
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Ishan Deshpande
- Department of Pharmaceutical Chemistry, Department of Anaesthesia and Perioperative Care, University of California, San Francisco, California, United States of America
| | - Jiahao Liang
- Department of Pharmaceutical Chemistry, Department of Anaesthesia and Perioperative Care, University of California, San Francisco, California, United States of America
| | - Jiewei Xu
- Department of Cellular and Molecular Pharmacology, Quantitative Biosciences Institute, University of California, San Francisco, California, United States of America
- J. David Gladstone Institutes, San Francisco, California, United States of America
| | - Sara L. Stubben
- Department of Oncological Sciences, Department of Biochemistry, Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Isaac B. Nelson
- Department of Oncological Sciences, Department of Biochemistry, Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Madison F. Walker
- Department of Oncological Sciences, Department of Biochemistry, Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Kouki Kawakami
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, Japan
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, Japan
| | - Nevan J. Krogan
- Department of Cellular and Molecular Pharmacology, Quantitative Biosciences Institute, University of California, San Francisco, California, United States of America
- J. David Gladstone Institutes, San Francisco, California, United States of America
| | - David J. Grunwald
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Ruth Hüttenhain
- Department of Cellular and Molecular Pharmacology, Quantitative Biosciences Institute, University of California, San Francisco, California, United States of America
- J. David Gladstone Institutes, San Francisco, California, United States of America
| | - Aashish Manglik
- Department of Pharmaceutical Chemistry, Department of Anaesthesia and Perioperative Care, University of California, San Francisco, California, United States of America
| | - Benjamin R. Myers
- Department of Oncological Sciences, Department of Biochemistry, Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
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8
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Tirou L, Russo M, Faure H, Pellegrino G, Demongin C, Daynac M, Sharif A, Amosse J, Le Lay S, Denis R, Luquet S, Taouis M, Benomar Y, Ruat M. Sonic Hedgehog receptor Patched deficiency in astrocytes enhances glucose metabolism in mice. Mol Metab 2021; 47:101172. [PMID: 33513436 PMCID: PMC7893488 DOI: 10.1016/j.molmet.2021.101172] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 01/12/2021] [Accepted: 01/21/2021] [Indexed: 01/06/2023] Open
Abstract
Objective Astrocytes are glial cells proposed as the main Sonic hedgehog (Shh)-responsive cells in the adult brain. Their roles in mediating Shh functions are still poorly understood. In the hypothalamus, astrocytes support neuronal circuits implicated in the regulation of energy metabolism. In this study, we investigated the impact of genetic activation of Shh signaling on hypothalamic astrocytes and characterized its effects on energy metabolism. Methods We analyzed the distribution of gene transcripts of the Shh pathway (Ptc, Gli1, Gli2, and Gli3) in astrocytes using single molecule fluorescence in situ hybridization combined with immunohistofluorescence of Shh peptides by Western blotting in the adult mouse hypothalamus. Based on the metabolic phenotype, we characterized Glast-CreERT2-YFP-Ptc−/− (YFP-Ptc−/−) mice and their controls over time and under a high-fat diet (HFD) to investigate the potential effects of conditional astrocytic deletion of the Shh receptor Patched (Ptc) on metabolic efficiency, insulin sensitivity, and systemic glucose metabolism. Molecular and biochemical assays were used to analyze the alteration of key pathways modulating energy metabolism, insulin sensitivity, glucose uptake, and inflammation. Primary astrocyte cultures were used to evaluate a potential role of Shh signaling in astrocytic glucose uptake. Results Shh peptides were the highest in the hypothalamic extracts of adult mice and a large population of hypothalamic astrocytes expressed Ptc and Gli1-3 mRNAs. Characterization of Shh signaling after conditional Ptc deletion in the YFP-Ptc−/− mice revealed heterogeneity in hypothalamic astrocyte populations. Interestingly, activation of Shh signaling in Glast+ astrocytes enhanced insulin responsiveness as evidenced by glucose and insulin tolerance tests. This effect was maintained over time and associated with lower blood insulin levels and also observed under a HFD. The YFP-Ptc−/− mice exhibited a lean phenotype with the absence of body weight gain and a marked reduction of white and brown adipose tissues accompanied by increased whole-body fatty acid oxidation. In contrast, food intake, locomotor activity, and body temperature were not altered. At the cellular level, Ptc deletion did not affect glucose uptake in primary astrocyte cultures. In the hypothalamus, activation of the astrocytic Shh pathway was associated with the upregulation of transcripts coding for the insulin receptor and liver kinase B1 (LKB1) after 4 weeks and the glucose transporter GLUT-4 after 32 weeks. Conclusions Here, we define hypothalamic Shh action on astrocytes as a novel master regulator of energy metabolism. In the hypothalamus, astrocytic Shh signaling could be critically involved in preventing both aging- and obesity-related metabolic disorders. Astrocytes exhibit differences in regulating the hedgehog signaling pathway. Deletion of Ptc in Glast+ cells prevents body weight gain and insulin resistance. Deletion of Ptc in Glast+ cells increases β oxidation. Central hedgehog signaling participates in the regulation of whole-body metabolism.
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Affiliation(s)
- Linda Tirou
- CNRS, Paris-Saclay University, UMR-9197, Neuroscience Paris-Saclay Institute, F-91198, Gif-sur-Yvette, France
| | - Mariagiovanna Russo
- CNRS, Paris-Saclay University, UMR-9197, Neuroscience Paris-Saclay Institute, F-91198, Gif-sur-Yvette, France
| | - Helene Faure
- CNRS, Paris-Saclay University, UMR-9197, Neuroscience Paris-Saclay Institute, F-91198, Gif-sur-Yvette, France
| | - Giuliana Pellegrino
- CNRS, Paris-Saclay University, UMR-9197, Neuroscience Paris-Saclay Institute, F-91198, Gif-sur-Yvette, France
| | - Clement Demongin
- CNRS, Paris-Saclay University, UMR-9197, Neuroscience Paris-Saclay Institute, F-91198, Gif-sur-Yvette, France
| | - Mathieu Daynac
- CNRS, Paris-Saclay University, UMR-9197, Neuroscience Paris-Saclay Institute, F-91198, Gif-sur-Yvette, France
| | - Ariane Sharif
- Univ. Lille, Inserm, CHU Lille, U1172 - LilNCog (JPARC) - Lille Neurosciences & Cognition, F-59000, Lille, France
| | - Jeremy Amosse
- Univ. Angers SFR ICAT, F-49100, Angers, France; IRSET Laboratory, Inserm, UMR, 1085, Rennes, France
| | - Soazig Le Lay
- Univ. Angers SFR ICAT, F-49100, Angers, France; Univ. Nantes, CNRS, Inserm, Thorax Institut, F-44000, Nantes, France
| | - Raphaël Denis
- Univ. Paris, BFA, UMR 8251, CNRS, F-75013, Paris, France
| | - Serge Luquet
- Univ. Paris, BFA, UMR 8251, CNRS, F-75013, Paris, France
| | - Mohammed Taouis
- CNRS, Paris-Saclay University, UMR 9197, Neuroscience Paris-Saclay Institute, Molecular Neuroendocrinology of Food Intake, Orsay, France
| | - Yacir Benomar
- CNRS, Paris-Saclay University, UMR 9197, Neuroscience Paris-Saclay Institute, Molecular Neuroendocrinology of Food Intake, Orsay, France
| | - Martial Ruat
- CNRS, Paris-Saclay University, UMR-9197, Neuroscience Paris-Saclay Institute, F-91198, Gif-sur-Yvette, France.
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Kozielewicz P, Turku A, Bowin CF, Petersen J, Valnohova J, Cañizal MCA, Ono Y, Inoue A, Hoffmann C, Schulte G. Structural insight into small molecule action on Frizzleds. Nat Commun 2020; 11:414. [PMID: 31964872 PMCID: PMC6972889 DOI: 10.1038/s41467-019-14149-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 12/09/2019] [Indexed: 01/05/2023] Open
Abstract
WNT-Frizzled (FZD) signaling plays a critical role in embryonic development, stem cell regulation and tissue homeostasis. FZDs are linked to severe human pathology and are seen as a promising target for therapy. Despite intense efforts, no small molecule drugs with distinct efficacy have emerged. Here, we identify the Smoothened agonist SAG1.3 as a partial agonist of FZD6 with limited subtype selectivity. Employing extensive in silico analysis, resonance energy transfer- and luciferase-based assays we describe the mode of action of SAG1.3. We define the ability of SAG1.3 to bind to FZD6 and to induce conformational changes in the receptor, recruitment and activation of G proteins and dynamics in FZD–Dishevelled interaction. Our results provide the proof-of-principle that FZDs are targetable by small molecules acting on their seven transmembrane spanning core. Thus, we provide a starting point for a structure-guided and mechanism-based drug discovery process to exploit the potential of FZDs as therapeutic targets. WNT-Frizzled (FZD) signaling plays a critical role in embryonic development, tissue homeostasis and human disease but no small molecule drugs targeting FZD with distinct efficacy have emerged so far. Here, authors identify the Smoothened agonist SAG1.3 as a partial agonist for FZD6 with limited subtype selectivity.
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Affiliation(s)
- Paweł Kozielewicz
- Section of Receptor Biology & Signaling, Department of Physiology & Pharmacology, Karolinska Institutet, S-17165, Stockholm, Sweden
| | - Ainoleena Turku
- Section of Receptor Biology & Signaling, Department of Physiology & Pharmacology, Karolinska Institutet, S-17165, Stockholm, Sweden
| | - Carl-Fredrik Bowin
- Section of Receptor Biology & Signaling, Department of Physiology & Pharmacology, Karolinska Institutet, S-17165, Stockholm, Sweden
| | - Julian Petersen
- Section of Receptor Biology & Signaling, Department of Physiology & Pharmacology, Karolinska Institutet, S-17165, Stockholm, Sweden
| | - Jana Valnohova
- Section of Receptor Biology & Signaling, Department of Physiology & Pharmacology, Karolinska Institutet, S-17165, Stockholm, Sweden
| | - Maria Consuelo Alonso Cañizal
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Str. 9, 97078, Würzburg, Germany.,Institute for Molecular Cell Biology, CMB-Center for Molecular Biomedicine, University Hospital Jena, Friedrich-Schiller University Jena, Hans-Knöll-Strasse 2, 07745, Jena, Germany
| | - Yuki Ono
- Department of Pharmacological Sciences, Tohoku University, Sendai, 980-8578, Japan
| | - Asuka Inoue
- Department of Pharmacological Sciences, Tohoku University, Sendai, 980-8578, Japan
| | - Carsten Hoffmann
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Str. 9, 97078, Würzburg, Germany.,Institute for Molecular Cell Biology, CMB-Center for Molecular Biomedicine, University Hospital Jena, Friedrich-Schiller University Jena, Hans-Knöll-Strasse 2, 07745, Jena, Germany
| | - Gunnar Schulte
- Section of Receptor Biology & Signaling, Department of Physiology & Pharmacology, Karolinska Institutet, S-17165, Stockholm, Sweden.
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10
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Rapid, direct activity assays for Smoothened reveal Hedgehog pathway regulation by membrane cholesterol and extracellular sodium. Proc Natl Acad Sci U S A 2017; 114:E11141-E11150. [PMID: 29229834 DOI: 10.1073/pnas.1717891115] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Hedgehog signaling specifies tissue patterning and renewal, and pathway components are commonly mutated in certain malignancies. Although central to ensuring appropriate pathway activity in all Hedgehog-responsive cells, how the transporter-like receptor Patched1 regulates the seven-transmembrane protein Smoothened remains mysterious, partially due to limitations in existing tools and experimental systems. Here we employ direct, real-time, biochemical and physiology-based approaches to monitor Smoothened activity in cellular and in vitro contexts. Patched1-Smoothened coupling is rapid, dynamic, and can be recapitulated without cilium-specific proteins or lipids. By reconstituting purified Smoothened in vitro, we show that cholesterol within the bilayer is sufficient for constitutive Smoothened activation. Cholesterol effects occur independently of the lipid-binding Smoothened extracellular domain, a region that is dispensable for Patched1-Smoothened coupling. Finally, we show that Patched1 specifically requires extracellular Na+ to regulate Smoothened in our assays, raising the possibility that a Na+ gradient provides the energy source for Patched1 catalytic activity. Our work suggests a hypothesis wherein Patched1, chemiosmotically driven by the transmembrane Na+ gradient common to metazoans, regulates Smoothened by shielding its heptahelical domain from cholesterol, or by providing an inhibitor that overrides this cholesterol activation.
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11
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Manetti F, Petricci E, Gabrielli A, Mann A, Faure H, Gorojankina T, Brasseur L, Hoch L, Ruat M, Taddei M. Design, synthesis and biological characterization of a new class of osteogenic (1H)-quinolone derivatives. Eur J Med Chem 2016; 121:747-757. [DOI: 10.1016/j.ejmech.2016.05.062] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 05/26/2016] [Accepted: 05/27/2016] [Indexed: 12/11/2022]
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12
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Gorojankina T. Hedgehog signaling pathway: a novel model and molecular mechanisms of signal transduction. Cell Mol Life Sci 2016; 73:1317-32. [PMID: 26762301 PMCID: PMC11108571 DOI: 10.1007/s00018-015-2127-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 12/23/2015] [Accepted: 12/23/2015] [Indexed: 12/21/2022]
Abstract
The Hedgehog (Hh) signaling pathway has numerous roles in the control of cell proliferation, tissue patterning and stem cell maintenance. In spite of intensive study, the mechanisms of Hh signal transduction are not completely understood. Here I review published data and present a novel model of vertebrate Hh signaling suggesting that Smoothened (Smo) functions as a G-protein-coupled receptor in cilia. This is the first model to propose molecular mechanisms for the major steps of Hh signaling, including inhibition of Smo by Patched, Smo activation, and signal transduction from active Smo to Gli transcription factors. It also suggests a novel role for the negative pathway regulators Sufu and PKA in these processes.
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Affiliation(s)
- Tatiana Gorojankina
- Neuroscience Paris-Saclay Institute (Neuro-PSI), UMR 9197, CNRS, Université Paris-Sud, Bât. 32/33, CNRS, 91190, Gif-sur-Yvette, France.
- Institut Curie, Centre de Recherche, Orsay, France.
- CNRS UMR3347, 91400, Orsay, France.
- Univ. Paris Sud, Université Paris Saclay, Orsay, France.
- INSERM U1021, 91400, Orsay, France.
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13
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Villanueva H, Visbal AP, Obeid NF, Ta AQ, Faruki AA, Wu MF, Hilsenbeck SG, Shaw CA, Yu P, Plummer NW, Birnbaumer L, Lewis MT. An essential role for Gα(i2) in Smoothened-stimulated epithelial cell proliferation in the mammary gland. Sci Signal 2015; 8:ra92. [PMID: 26373672 DOI: 10.1126/scisignal.aaa7355] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Hedgehog (Hh) signaling is critical for organogenesis, tissue homeostasis, and stem cell maintenance. The gene encoding Smoothened (SMO), the primary effector of Hh signaling, is expressed aberrantly in human breast cancer, as well as in other cancers. In mice that express a constitutively active form of SMO that does not require Hh stimulation in mammary glands, the cells near the transgenic cells proliferate and participate in hyperplasia formation. Although SMO is a seven-transmembrane receptor like G protein-coupled receptors (GPCRs), SMO-mediated activation of the Gli family of transcription factors is not known to involve G proteins. However, data from Drosophila and mammalian cell lines indicate that SMO functions as a GPCR that couples to heterotrimeric G proteins of the pertussis toxin (PTX)-sensitive Gαi class. Using genetically modified mice, we demonstrated that SMO signaling through G proteins occurred in the mammary gland in vivo. SMO-induced stimulation of proliferation was PTX-sensitive and required Gαi2, but not Gαi1, Gαi3, or activation of Gli1 or Gli2. Our findings show that activated SMO functions as a GPCR to stimulate proliferation in vivo, a finding that may have clinical importance because most SMO-targeted agents have been selected based largely on their ability to block Gli-mediated transcription.
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Affiliation(s)
- Hugo Villanueva
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA. Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Adriana P Visbal
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA. Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Nadine F Obeid
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Andrew Q Ta
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Adeel A Faruki
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Meng-Fen Wu
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Susan G Hilsenbeck
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA. Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Chad A Shaw
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Peng Yu
- Department of Electrical and Computer Engineering, TEES-AgriLife Center for Bioinformatics and Genomic Systems Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Nicholas W Plummer
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Lutz Birnbaumer
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Michael T Lewis
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA. Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA. Department of Radiology, Baylor College of Medicine, Houston, TX 77030, USA.
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14
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Hoch L, Faure H, Roudaut H, Schoenfelder A, Mann A, Girard N, Bihannic L, Ayrault O, Petricci E, Taddei M, Rognan D, Ruat M. MRT-92 inhibits Hedgehog signaling by blocking overlapping binding sites in the transmembrane domain of the Smoothened receptor. FASEB J 2015; 29:1817-29. [PMID: 25636740 DOI: 10.1096/fj.14-267849] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 12/18/2014] [Indexed: 12/28/2022]
Abstract
The Smoothened (Smo) receptor, a member of class F G protein-coupled receptors, is the main transducer of the Hedgehog (Hh) signaling pathway implicated in a wide range of developmental and adult processes. Smo is the target of anticancer drugs that bind to a long and narrow cavity in the 7-transmembrane (7TM) domain. X-ray structures of human Smo (hSmo) bound to several ligands have revealed 2 types of 7TM-directed antagonists: those binding mostly to extracellular loops (site 1, e.g., LY2940680) and those penetrating deeply in the 7TM cavity (site 2, e.g., SANT-1). Here we report the development of the acylguanidine MRT-92, which displays subnanomolar antagonist activity against Smo in various Hh cell-based assays. MRT-92 inhibits rodent cerebellar granule cell proliferation induced by Hh pathway activation through pharmacologic (half maximal inhibitory concentration [IC50] = 0.4 nM) or genetic manipulation. Using [(3)H]MRT-92 (Kd = 0.3 nM for hSmo), we created a comprehensive framework for the interaction of small molecule modulators with hSmo and for understanding chemoresistance linked to hSmo mutations. Guided by molecular docking and site-directed mutagenesis data, our work convincingly confirms that MRT-92 simultaneously recognized and occupied both sites 1 and 2. Our data demonstrate the existence of a third type of Smo antagonists, those entirely filling the Smo binding cavity from the upper extracellular part to the lower cytoplasmic-proximal subpocket. Our studies should help design novel potent Smo antagonists and more effective therapeutic strategies for treating Hh-linked cancers and associated chemoresistance.
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Affiliation(s)
- Lucile Hoch
- *Centre National de la Recherche Scientifique, Unité Mixte de Recherche-9197, Neuroscience Paris-Saclay Institute, Molecules Circuits Department, Signal Transduction and Developmental Neuropharmacology Team, Gif-sur-Yvette, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-7200, Laboratoire d'Innovation Thérapeutique, Université de Strasbourg, Illkirch, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-3306, Institut National de la Santé et de la Recherche Médicale U1005, Institut Curie, Centre Universitaire, Orsay, France; and Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy
| | - Helene Faure
- *Centre National de la Recherche Scientifique, Unité Mixte de Recherche-9197, Neuroscience Paris-Saclay Institute, Molecules Circuits Department, Signal Transduction and Developmental Neuropharmacology Team, Gif-sur-Yvette, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-7200, Laboratoire d'Innovation Thérapeutique, Université de Strasbourg, Illkirch, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-3306, Institut National de la Santé et de la Recherche Médicale U1005, Institut Curie, Centre Universitaire, Orsay, France; and Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy
| | - Hermine Roudaut
- *Centre National de la Recherche Scientifique, Unité Mixte de Recherche-9197, Neuroscience Paris-Saclay Institute, Molecules Circuits Department, Signal Transduction and Developmental Neuropharmacology Team, Gif-sur-Yvette, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-7200, Laboratoire d'Innovation Thérapeutique, Université de Strasbourg, Illkirch, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-3306, Institut National de la Santé et de la Recherche Médicale U1005, Institut Curie, Centre Universitaire, Orsay, France; and Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy
| | - Angele Schoenfelder
- *Centre National de la Recherche Scientifique, Unité Mixte de Recherche-9197, Neuroscience Paris-Saclay Institute, Molecules Circuits Department, Signal Transduction and Developmental Neuropharmacology Team, Gif-sur-Yvette, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-7200, Laboratoire d'Innovation Thérapeutique, Université de Strasbourg, Illkirch, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-3306, Institut National de la Santé et de la Recherche Médicale U1005, Institut Curie, Centre Universitaire, Orsay, France; and Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy
| | - Andre Mann
- *Centre National de la Recherche Scientifique, Unité Mixte de Recherche-9197, Neuroscience Paris-Saclay Institute, Molecules Circuits Department, Signal Transduction and Developmental Neuropharmacology Team, Gif-sur-Yvette, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-7200, Laboratoire d'Innovation Thérapeutique, Université de Strasbourg, Illkirch, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-3306, Institut National de la Santé et de la Recherche Médicale U1005, Institut Curie, Centre Universitaire, Orsay, France; and Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy
| | - Nicolas Girard
- *Centre National de la Recherche Scientifique, Unité Mixte de Recherche-9197, Neuroscience Paris-Saclay Institute, Molecules Circuits Department, Signal Transduction and Developmental Neuropharmacology Team, Gif-sur-Yvette, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-7200, Laboratoire d'Innovation Thérapeutique, Université de Strasbourg, Illkirch, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-3306, Institut National de la Santé et de la Recherche Médicale U1005, Institut Curie, Centre Universitaire, Orsay, France; and Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy
| | - Laure Bihannic
- *Centre National de la Recherche Scientifique, Unité Mixte de Recherche-9197, Neuroscience Paris-Saclay Institute, Molecules Circuits Department, Signal Transduction and Developmental Neuropharmacology Team, Gif-sur-Yvette, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-7200, Laboratoire d'Innovation Thérapeutique, Université de Strasbourg, Illkirch, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-3306, Institut National de la Santé et de la Recherche Médicale U1005, Institut Curie, Centre Universitaire, Orsay, France; and Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy
| | - Olivier Ayrault
- *Centre National de la Recherche Scientifique, Unité Mixte de Recherche-9197, Neuroscience Paris-Saclay Institute, Molecules Circuits Department, Signal Transduction and Developmental Neuropharmacology Team, Gif-sur-Yvette, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-7200, Laboratoire d'Innovation Thérapeutique, Université de Strasbourg, Illkirch, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-3306, Institut National de la Santé et de la Recherche Médicale U1005, Institut Curie, Centre Universitaire, Orsay, France; and Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy
| | - Elena Petricci
- *Centre National de la Recherche Scientifique, Unité Mixte de Recherche-9197, Neuroscience Paris-Saclay Institute, Molecules Circuits Department, Signal Transduction and Developmental Neuropharmacology Team, Gif-sur-Yvette, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-7200, Laboratoire d'Innovation Thérapeutique, Université de Strasbourg, Illkirch, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-3306, Institut National de la Santé et de la Recherche Médicale U1005, Institut Curie, Centre Universitaire, Orsay, France; and Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy
| | - Maurizio Taddei
- *Centre National de la Recherche Scientifique, Unité Mixte de Recherche-9197, Neuroscience Paris-Saclay Institute, Molecules Circuits Department, Signal Transduction and Developmental Neuropharmacology Team, Gif-sur-Yvette, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-7200, Laboratoire d'Innovation Thérapeutique, Université de Strasbourg, Illkirch, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-3306, Institut National de la Santé et de la Recherche Médicale U1005, Institut Curie, Centre Universitaire, Orsay, France; and Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy
| | - Didier Rognan
- *Centre National de la Recherche Scientifique, Unité Mixte de Recherche-9197, Neuroscience Paris-Saclay Institute, Molecules Circuits Department, Signal Transduction and Developmental Neuropharmacology Team, Gif-sur-Yvette, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-7200, Laboratoire d'Innovation Thérapeutique, Université de Strasbourg, Illkirch, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-3306, Institut National de la Santé et de la Recherche Médicale U1005, Institut Curie, Centre Universitaire, Orsay, France; and Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy
| | - Martial Ruat
- *Centre National de la Recherche Scientifique, Unité Mixte de Recherche-9197, Neuroscience Paris-Saclay Institute, Molecules Circuits Department, Signal Transduction and Developmental Neuropharmacology Team, Gif-sur-Yvette, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-7200, Laboratoire d'Innovation Thérapeutique, Université de Strasbourg, Illkirch, France; Centre National de la Recherche Scientifique, Unité Mixte de Recherche-3306, Institut National de la Santé et de la Recherche Médicale U1005, Institut Curie, Centre Universitaire, Orsay, France; and Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy
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15
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Abstract
The Smoothened (Smo) receptor is a major component involved in signal transduction of the Hedgehog (Hh) morphogens both during embryogenesis and in the adult. Smo antagonists represent a promi-sing alternative for the treatment of cancers linked to abnormal Hh signalling. The crystal structure of the human Smo receptor bound to an antitumour agent demonstrates that this receptor belongs to the superfamily of G-protein coupled receptors. The antagonist binds to a pocket localized at the extracellular side formed by the seven transmembrane domains and the complex arrangement of the unusually long extracellular loops. The structure of the Smo receptor will promote the development of small molecules interacting with a key therapeutic target with interests in regenerative medicine and cancer.
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Affiliation(s)
- Martial Ruat
- CNRS, Institut de neurobiologie Alfred Fessard, laboratoire de neurobiologie et du développement, UPR 3294, équipe transduction du signal et neuropharmacologie développementale, bâtiment 33, 1, avenue de la Terrasse, 91198 Gif-sur-Yvette, France
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16
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Giovinazzo F, Malpeli G, Zanini S, Parenti M, Piemonti L, Colombatti M, Valenti MT, Dalle Carbonare L, Scarpa A, Sinnett-Smith J, Rozengurt E, Bassi C, Innamorati G. Ectopic expression of the heterotrimeric G15 protein in pancreatic carcinoma and its potential in cancer signal transduction. Cell Signal 2013; 25:651-9. [PMID: 23200847 DOI: 10.1016/j.cellsig.2012.11.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Revised: 11/07/2012] [Accepted: 11/22/2012] [Indexed: 11/22/2022]
Abstract
G15 is a heterotrimeric G protein selectively expressed in immature cell lineages in adult tissues that feature higher cell renewal potential. It promiscuously couples a wide variety of G protein-coupled receptors (GPCRs) to phospholipase C. Intriguingly, G15 is poorly affected by GPCR desensitization. We show here that G15 α-subunit (Gα15) supports sustained stimulation of PKD1 by a constitutively desensitized GPCR co-transfected over a negative cell background. Based on the fact that PKD1 is a multifunctional protein kinase activated by PKC and known for promoting oncogenic signaling, we hypothesized that, if expressed out of its natural cell context, G15 might promote tumor growth. A screening for Gα15 mRNA expression pointed to pancreatic carcinoma among different human cancer cell types and revealed significant expression in human tumor biopsies xenografted in mice. In addition, G15 ectopic presence could functionally contribute to the transformation process since siRNA-induced depletion of Gα15 in pancreatic carcinoma cell lines dramatically inhibited anchorage-independent growth and resistance to the lack of nutrients. Altogether, our findings suggest that G15 supports tumorigenic signaling in pancreas and hence it may be considered as a novel potential target for the therapy of this form of cancer.
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Affiliation(s)
- Francesco Giovinazzo
- Laboratory of Translational Surgery, University Laboratories of Medical Research (LURM), University of Verona, 37134 Verona, Italy
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17
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Gorojankina T, Hoch L, Faure H, Roudaut H, Traiffort E, Schoenfelder A, Girard N, Mann A, Manetti F, Solinas A, Petricci E, Taddei M, Ruat M. Discovery, molecular and pharmacological characterization of GSA-10, a novel small-molecule positive modulator of Smoothened. Mol Pharmacol 2013; 83:1020-9. [PMID: 23448715 DOI: 10.1124/mol.112.084590] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Activation of the Smoothened (Smo) receptor mediates Hedgehog (Hh) signaling. Hh inhibitors are in clinical trials for cancer, and small-molecule Smo agonists may have therapeutic interests in regenerative medicine. Here, we have generated and validated a pharmacophoric model for Smo agonists and used this model for the virtual screening of a library of commercially available compounds. Among the 20 top-scoring ligands, we have identified and characterized a novel quinolinecarboxamide derivative, propyl 4-(1-hexyl-4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxamido) benzoate, (GSA-10), as a Smo agonist. GSA-10 fits to the agonist pharmacophoric model with two hydrogen bond acceptor groups and four hydrophobic regions. Using pharmacological, biochemical, and molecular approaches, we provide compelling evidence that GSA-10 acts at Smo to promote the differentiation of multipotent mesenchymal progenitor cells into osteoblasts. However, this molecule does not display the hallmarks of reference Smo agonists. Remarkably, GSA-10 does not recognize the classic bodipy-cyclopamine binding site. Its effect on cell differentiation is inhibited by Smo antagonists, such as MRT-83, SANT-1, LDE225, and M25 in the nanomolar range, by GDC-0449 in the micromolar range, but not by cyclopamine and CUR61414. Thus, GSA-10 allows the pharmacological characterization of a novel Smo active site, which is notably not targeted to the primary cilium and strongly potentiated by forskolin and cholera toxin. GSA-10 belongs to a new class of Smo agonists and will be helpful for dissecting Hh mechanism of action, with important implications in physiology and in therapy.
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Affiliation(s)
- Tatiana Gorojankina
- CNRS, UPR-3294, Laboratoire de Neurobiologie et Développement, Institut de Neurobiologie Alfred Fessard IFR2118, Gif-sur-Yvette, France
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18
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Solinas A, Faure H, Roudaut H, Traiffort E, Schoenfelder A, Mann A, Manetti F, Taddei M, Ruat M. Acylthiourea, Acylurea, and Acylguanidine Derivatives with Potent Hedgehog Inhibiting Activity. J Med Chem 2012; 55:1559-71. [DOI: 10.1021/jm2013369] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Antonio Solinas
- Dipartimento Farmaco Chimico Tecnologico, Università degli Studi di Siena, Via A. Moro
2, I-53100 Siena, Italy
| | - Hélène Faure
- CNRS, UPR-3294, Laboratoire de Neurobiologie et Développement, Institut de Neurobiologie Alfred Fessard IFR2118, Signal
Transduction and Developmental Neuropharmacology Team, 1 Avenue de
la Terrasse, F-91198 Gif-sur-Yvette, France
| | - Hermine Roudaut
- CNRS, UPR-3294, Laboratoire de Neurobiologie et Développement, Institut de Neurobiologie Alfred Fessard IFR2118, Signal
Transduction and Developmental Neuropharmacology Team, 1 Avenue de
la Terrasse, F-91198 Gif-sur-Yvette, France
| | - Elisabeth Traiffort
- CNRS, UPR-3294, Laboratoire de Neurobiologie et Développement, Institut de Neurobiologie Alfred Fessard IFR2118, Signal
Transduction and Developmental Neuropharmacology Team, 1 Avenue de
la Terrasse, F-91198 Gif-sur-Yvette, France
| | - Angèle Schoenfelder
- Laboratoire d’Innovation Thérapeutique,
UMR-7200, CNRS—Université de Strasbourg, 74 Route du Rhin, F-67401 Illkirch, France
| | - André Mann
- Laboratoire d’Innovation Thérapeutique,
UMR-7200, CNRS—Université de Strasbourg, 74 Route du Rhin, F-67401 Illkirch, France
| | - Fabrizio Manetti
- Dipartimento Farmaco Chimico Tecnologico, Università degli Studi di Siena, Via A. Moro
2, I-53100 Siena, Italy
| | - Maurizio Taddei
- Dipartimento Farmaco Chimico Tecnologico, Università degli Studi di Siena, Via A. Moro
2, I-53100 Siena, Italy
| | - Martial Ruat
- CNRS, UPR-3294, Laboratoire de Neurobiologie et Développement, Institut de Neurobiologie Alfred Fessard IFR2118, Signal
Transduction and Developmental Neuropharmacology Team, 1 Avenue de
la Terrasse, F-91198 Gif-sur-Yvette, France
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19
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Yoshimura K, Kawate T, Takeda S. Signaling through the primary cilium affects glial cell survival under a stressed environment. Glia 2011; 59:333-44. [PMID: 21125655 DOI: 10.1002/glia.21105] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Sensing extracellular milieu is a fundamental requirement of cells. To facilitate and specify sensory reception, mammalian cells develop an antenna-like structure denoted as the primary cilia. Nearly all interphase and nondividing cells in vertebrates have a single, nonmotile seemingly unspecialized cilium (called a primary cilium). In the central nervous system, astrocytes express primary cilia, but their function in astrocytes has not been examined. Recent studies have shown that primary cilia unite receptors and the machinery of signal-transduction components, such as Wnt and Hedgehog (Hh) signaling cascades. Although, Hh signaling cascades are known to be activated in various cells during development, their physiological functions in the adult nervous system, especially in glial cells, are still unknown. In this study, we reveal that glial primary cilia receive the Hh signal and regulate the survival of astrocytes under stressed conditions such as starvation. Interestingly, increased astrocyte survival was reversed by knockdown of Ift20, which is one of the main components for building primary cilia. These results collectively indicate that the activation of Hh signaling in the primary cilia plays an important role in the survival of astrocytes under stressed conditions.
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Affiliation(s)
- Kentaro Yoshimura
- Department of Anatomy and Cell Biology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi, 409-3898, Japan
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20
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Schulte G. International Union of Basic and Clinical Pharmacology. LXXX. The class Frizzled receptors. Pharmacol Rev 2011; 62:632-67. [PMID: 21079039 DOI: 10.1124/pr.110.002931] [Citation(s) in RCA: 160] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The receptor class Frizzled, which has recently been categorized as a separate group of G protein-coupled receptors by the International Union of Basic and Clinical Pharmacology, consists of 10 Frizzleds (FZD(1-10)) and Smoothened (SMO). The FZDs are activated by secreted lipoglycoproteins of the Wingless/Int-1 (WNT) family, whereas SMO is indirectly activated by the Hedgehog (HH) family of proteins acting on the transmembrane protein Patched (PTCH). Recent years have seen major advances in our knowledge about these seven-transmembrane-spanning proteins, including: receptor function, molecular mechanisms of signal transduction, and the receptor's role in embryonic patterning, physiology, cancer, and other diseases. Despite intense efforts, many question marks and challenges remain in mapping receptor-ligand interaction, signaling routes, mechanisms of specificity and how these molecular details underlie disease and also the receptor's important role in physiology. This review therefore focuses on the molecular aspects of WNT/FZD and HH/SMO signaling discussing receptor structure, mechanisms of signal transduction, accessory proteins, receptor dynamics, and the possibility of targeting these signaling pathways pharmacologically.
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Affiliation(s)
- Gunnar Schulte
- Section of Receptor Biology & Signaling, Dept. of Physiology & Pharmacology, Karolinska Institutet, Stockholm, Sweden.
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21
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Sonic hedgehog regulates discrete populations of astrocytes in the adult mouse forebrain. J Neurosci 2010; 30:13597-608. [PMID: 20943901 DOI: 10.1523/jneurosci.0830-10.2010] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Astrocytes are an essential component of the CNS, and recent evidence points to an increasing diversity of their functions. Identifying molecular pathways that mediate distinct astrocyte functions, is key to understanding how the nervous system operates in the intact and pathological states. In this study, we demonstrate that the Hedgehog (Hh) pathway, well known for its roles in the developing CNS, is active in astrocytes of the mature mouse forebrain in vivo. Using multiple genetic approaches, we show that regionally distinct subsets of astrocytes receive Hh signaling, indicating a molecular diversity between specific astrocyte populations. Furthermore, we identified neurons as a source of Sonic hedgehog (Shh) in the adult forebrain, suggesting that Shh signaling is involved in neuron-astrocyte communication. Attenuation of Shh signaling in postnatal astrocytes by targeted removal of Smoothened, an obligate Shh coreceptor, resulted in upregulation of GFAP and cellular hypertrophy specifically in astrocyte populations regulated by Shh signaling. Collectively, our findings demonstrate a role for neuron-derived Shh in regulating specific populations of differentiated astrocytes.
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22
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Faure H, Gorojankina T, Rice N, Dauban P, Dodd RH, Bräuner-Osborne H, Rognan D, Ruat M. Molecular determinants of non-competitive antagonist binding to the mouse GPRC6A receptor. Cell Calcium 2010; 46:323-32. [PMID: 19836834 DOI: 10.1016/j.ceca.2009.09.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Accepted: 09/16/2009] [Indexed: 10/20/2022]
Abstract
GPRC6A displays high sequence homology to the Ca2+-sensing receptor (CaSR). Here we report that the calcimimetic Calindol and the calcilytic NPS2143 antagonize increases in inositol phosphate elicited by L-ornithine-induced activation of mouse GPRC6A after transient coexpression with Galpha(qG66D) in HEK293 cells. The calcilytic Calhex 231 did not modulate this response. A three-dimensional model of the GPRC6A seven transmembrane domains (TMs) was constructed. It was used to identify seven residues strictly conserved within the CaSR and GPRC6A allosteric binding pockets, and previously demonstrated to interact with calcilytics or calcimimetics. The mutations F666A(3.32), F670A(3.36), W797A(6.48) caused a loss of L-ornithine ability to activate GPRC6A mutants. The F800A(6.51) mutant was not implicated in either Calindol or NPS 2143 recognition. The E816Q(7.39) mutation led to a loss of Calindol antagonist activity but was without effect on NPS2143 inhibitory response. In summary, these data suggest that Calindol is primarily anchored through an H-bond to E816(7.39) in TM7 and highlight important local differences at the level of the CaSR and GPRC6A allosteric binding pockets. We have identified the first antagonists of GPRC6A that could represent new tools to analyze GPRC6A functions and serve as chemical leads for the development of more specific modulators.
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Affiliation(s)
- Helene Faure
- CNRS, UPR9040, Institut de Neurobiologie Alfred Fessard-IFR 2118, Signal Transduction and Developmental Neuropharmacology Team, 1 Avenue de la Terrasse, F-91198 Gif-sur-Yvette, France
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23
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Manetti F, Faure H, Roudaut H, Gorojankina T, Traiffort E, Schoenfelder A, Mann A, Solinas A, Taddei M, Ruat M. Virtual screening-based discovery and mechanistic characterization of the acylthiourea MRT-10 family as smoothened antagonists. Mol Pharmacol 2010; 78:658-65. [PMID: 20664000 DOI: 10.1124/mol.110.065102] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The seven-transmembrane receptor Smoothened (Smo) is the major component involved in signal transduction of the Hedgehog (Hh) morphogens. Smo inhibitors represent a promising alternative for the treatment of several types of cancers linked to abnormal Hh signaling. Here, on the basis of experimental data, we generated and validated a pharmacophoric model for Smo inhibitors constituted by three hydrogen bond acceptor groups and three hydrophobic regions. We used this model for the virtual screening of a library of commercially available compounds. Visual and structural criteria allowed the selection of 20 top scoring ligands, and an acylthiourea, N-(3-benzamidophenylcarbamothioyl)-3,4,5-trimethoxybenzamide (MRT-10), was identified and characterized as a Smo antagonist. The corresponding acylurea, N-(3-benzamidophenylcarbamoyl)-3,4,5-trimethoxybenzamide (MRT-14), was synthesized and shown to display, in various Hh assays, an inhibitory potency comparable to or greater than that of reference Smo antagonists cyclopamine and N-((3S,5S)-1-(benzo[d][1,3]dioxol-5-ylmethyl)-5-(piperazine-1-carbonyl)pyrrolidin-3-yl)-N-(3-methoxybenzyl)-3,3-dimethylbutanamide (Cur61414). Focused virtual screening of the same library further identified five additional related antagonists. MRT-10 and MRT-14 constitute the first members of novel families of Smo antagonists. The described virtual screening approach is aimed at identifying novel modulators of Smo and of other G-protein coupled receptors.
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Affiliation(s)
- Fabrizio Manetti
- Dipartimento Farmaco Chimico Tecnologico, Università degli Studi di Siena, Siena, Italy
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24
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Zebrafish inositol polyphosphate kinases: new effectors of cilia and developmental signaling. ACTA ACUST UNITED AC 2009; 50:309-23. [PMID: 19914277 DOI: 10.1016/j.advenzreg.2009.10.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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25
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Chemoattractive Activity of Sonic Hedgehog in the Adult Subventricular Zone Modulates the Number of Neural Precursors Reaching the Olfactory Bulb. Stem Cells 2008; 26:2311-20. [DOI: 10.1634/stemcells.2008-0297] [Citation(s) in RCA: 340] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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26
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Zhang X, Harrington N, Moraes RC, Wu MF, Hilsenbeck SG, Lewis MT. Cyclopamine inhibition of human breast cancer cell growth independent of Smoothened (Smo). Breast Cancer Res Treat 2008; 115:505-21. [PMID: 18563554 DOI: 10.1007/s10549-008-0093-3] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Accepted: 06/04/2008] [Indexed: 11/25/2022]
Abstract
Altered hedgehog signaling is implicated in the development of approximately 20-25% of all cancers, especially those of soft tissues. Genetic evidence in mice as well as immunolocalization studies in human breast cancer specimens suggest that deregulated hedgehog signaling may contribute to breast cancer development. Indeed, two recent studies demonstrated that anchorage-dependent growth of some human breast cancer cell lines is impaired by cyclopamine, a potent hedgehog signaling antagonist targeting the Smoothened (SMO) protein. However, specificity of cyclopamine at the dosage required for growth inhibition (> or =10 microM) remained an open question. In this paper we demonstrate that hedgehog signaling antagonists, including cyclopamine, and a second compound, CUR0199691, can inhibit growth of estrogen receptor (ER)-positive and ER-negative tumorigenic breast cancer cells at elevated doses. However, our results indicate that, for most breast cancer cell lines, growth inhibition by these compounds can be independent of detectable Smo gene expression. Rather, our results suggest that cyclopamine and CUR0199691 have unique secondary molecular targets at the dosages required for growth inhibition that are unrelated to hedgehog signaling.
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MESH Headings
- Apoptosis/drug effects
- Binding, Competitive
- Breast Neoplasms/drug therapy
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Cell Adhesion/drug effects
- Cell Line, Tumor
- Cell Proliferation/drug effects
- Cholesterol/metabolism
- Drug Resistance, Neoplasm/drug effects
- Female
- Flow Cytometry
- Fluorescent Antibody Technique
- Gene Expression Regulation, Neoplastic/drug effects
- Hedgehog Proteins/genetics
- Hedgehog Proteins/metabolism
- Humans
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Estrogen/metabolism
- Receptors, G-Protein-Coupled/antagonists & inhibitors
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction
- Smoothened Receptor
- Veratrum Alkaloids/pharmacology
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Affiliation(s)
- Xiaomei Zhang
- Lester and Sue Smith Breast Center and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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27
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Grimaldi A, Tettamanti G, Acquati F, Bossi E, Guidali ML, Banfi S, Monti L, Valvassori R, de Eguileor M. A hedgehog homolog is involved in muscle formation and organization of Sepia officinalis (mollusca) mantle. Dev Dyn 2008; 237:659-71. [PMID: 18265019 DOI: 10.1002/dvdy.21453] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Our study focuses on the possible involvement of the Hedgehog (Hh) pathway in the differentiation of striated muscle fibres in cuttlefish (Sepia officinalis) mantle. We show here that both an hh-homolog signalling molecule and its receptor Patched (Ptc) are expressed in a specific population of myoblasts which differentiates into the radial fast fibres. To evaluate the functional significance of hh expression in developing cuttlefish, we inhibited the Hedgehog signalling pathway by means of cyclopamine treatment in cuttlefish embryos. In treated embryos, the gross anatomy was considerably compromised, displaying an extremely reduced mantle with a high degree of morphological abnormalities. TUNEL and BrdU assays showed that the absence of an hh signalling induces apoptosis and reduces the proliferation rate of muscle precursors. We therefore hypothesize a possible involvement of Hh and its receptor Ptc in the formation of striated muscle fibres in cuttlefish.
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Affiliation(s)
- Annalisa Grimaldi
- Dipartimento di Biologia Strutturale e Funzionale, Università dell'Insubria, Varese, Italy.
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28
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Masdeu C, Bernard V, Faure H, Traiffort E, Ruat M. Distribution of Smoothened at hippocampal mossy fiber synapses. Neuroreport 2007; 18:395-9. [PMID: 17435610 DOI: 10.1097/wnr.0b013e32801421ce] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The seven-transmembrane receptor Smoothened is essential for hedgehog signal transduction. In adulthood, the highest density of Smoothened mRNA is found in the granule cell layer of the dentate gyrus. There, Smoothened expression is regulated by the synaptic activity involving the glutamatergic transmission. The precise localization of Smoothened proteins, however, has not yet been reported. Here, we describe Smoothened protein distribution in the hippocampal mossy fibers using specific Smoothened antibodies. We provide evidences for their presynaptic localization, and using electron microscopy, show that Smoothened is located in close association with synaptic vesicles and rarely with the plasma membrane. These findings demonstrate that Smoothened is localized presynaptically and suggest that Smoothened signal transduction may be implicated in the complex aspects of mossy fiber function.
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Affiliation(s)
- Christelle Masdeu
- Laboratory of Cellular and Molecular Neurobiology, Neurobiology Institute Alfred Fessard-IFR 2118, Signal Transduction and Developmental Neuropharmacology Team, Gif-sur-Yvette, France
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29
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Abstract
Signalling by Hh (Hedgehog) proteins is among the most actively studied receptor-mediated phenomena relevant to development and post-embryonic homoeostatic events. The impact of signalling by the Hh proteins is profound, and work pertaining to the presentation of these proteins and the pathways engaged by them continues to yield unique insights into basic aspects of morphogenic signalling. We review here the mechanisms of signalling relevant to the actions of Hh proteins in vertebrates. We emphasize findings within the past several years on the recognition of, in particular, Sonic hedgehog by target cells, pathways of transduction employed by the seven-pass transmembrane protein Smoothened and end points of action, as manifest in the regulation of the Gli transcription factors. Topics of extended interest are those regarding the employment of heterotrimeric G-proteins and G-protein-coupled receptor kinases by Smoothened. We also address the pathways, insofar as known, linking Smoothened to the expression and stability of Gli1, Gli2 and Gli3. The mechanisms by which Hh proteins signal have few, if any, parallels. It is becoming clear in vertebrates, however, that several facets of signalling are shared in common with other venues of signalling. The challenge in understanding both the actions of Hh proteins and the overlapping forms of regulation will be in understanding, in molecular terms, both common and divergent signalling events.
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Affiliation(s)
- Natalia A Riobo
- Department of Emergency Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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30
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Lewis MT, Visbal AP. The hedgehog signaling network, mammary stem cells, and breast cancer: connections and controversies. ERNST SCHERING FOUNDATION SYMPOSIUM PROCEEDINGS 2007:181-217. [PMID: 17939302 DOI: 10.1007/2789_2007_051] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Several signal transduction networks have been implicated in the regulation of mammary epithelial stem cell self-renewal and maintenance (Kalirai and Clarke 2006; Liu et al. 2005). These signaling networks include those of the Wnt, Notch, TGFO, EGF, FGF, IGF, and most recently, the Hedgehog (Hh) families of secreted ligands. However, we currently know very little about the cellular and molecular mechanisms by which these signaling pathways function to regulate normal epithelial stem/progenitor cells. What is clear is that the regulatory signaling networks thought to control normal stem/progenitor cell self-renewal and maintenance are, with the current sole exception of the hedgehog network, well-documented to have contributory roles in mammary cancer development and disease progression when misregulated. In this review, genetic regulation of mammary gland development by hedgehog network genes is outlined, highlighting a developing controversy as to whether activated hedgehog signaling regulates normal regenerative mammary epithelial stem cells or, indeed, whether activated hedgehog signaling functions at all in ductal development. In addition, the question of whether inappropriate hedgehog network activation influences breast cancer development is addressed, with emphasis on the prospects for using hedgehog signaling antagonists clinically for breast cancer treatment or prevention.
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Affiliation(s)
- M T Lewis
- Baylor Breast Center and Department of Molecular and Cellular Biology, Baylor College of Medicine, Room N1210; MS:BCM600, One Baylor Plaza, 77030 Houston, TX, USA.
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