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Griffiths SC, Tan J, Wagner A, Blazer LL, Adams JJ, Srinivasan S, Moghisaei S, Sidhu SS, Siebold C, Ho HYH. Structure and function of the ROR2 cysteine-rich domain in vertebrate noncanonical WNT5A signaling. eLife 2024; 13:e71980. [PMID: 38780011 PMCID: PMC11219042 DOI: 10.7554/elife.71980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 05/17/2024] [Indexed: 05/25/2024] Open
Abstract
The receptor tyrosine kinase ROR2 mediates noncanonical WNT5A signaling to orchestrate tissue morphogenetic processes, and dysfunction of the pathway causes Robinow syndrome, brachydactyly B, and metastatic diseases. The domain(s) and mechanisms required for ROR2 function, however, remain unclear. We solved the crystal structure of the extracellular cysteine-rich (CRD) and Kringle (Kr) domains of ROR2 and found that, unlike other CRDs, the ROR2 CRD lacks the signature hydrophobic pocket that binds lipids/lipid-modified proteins, such as WNTs, suggesting a novel mechanism of ligand reception. Functionally, we showed that the ROR2 CRD, but not other domains, is required and minimally sufficient to promote WNT5A signaling, and Robinow mutations in the CRD and the adjacent Kr impair ROR2 secretion and function. Moreover, using function-activating and -perturbing antibodies against the Frizzled (FZ) family of WNT receptors, we demonstrate the involvement of FZ in WNT5A-ROR signaling. Thus, ROR2 acts via its CRD to potentiate the function of a receptor super-complex that includes FZ to transduce WNT5A signals.
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Affiliation(s)
- Samuel C Griffiths
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of OxfordOxfordUnited Kingdom
| | - Jia Tan
- Department of Cell Biology and Human Anatomy, University of California, Davis School of MedicineDavisUnited States
| | - Armin Wagner
- Science Division, Diamond Light Source, Harwell Science and Innovation CampusDidcotUnited Kingdom
| | - Levi L Blazer
- School of Pharmacy, University of WaterlooWaterlooCanada
| | | | - Srisathya Srinivasan
- Department of Cell Biology and Human Anatomy, University of California, Davis School of MedicineDavisUnited States
| | - Shayan Moghisaei
- Department of Cell Biology and Human Anatomy, University of California, Davis School of MedicineDavisUnited States
| | | | - Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of OxfordOxfordUnited Kingdom
| | - Hsin-Yi Henry Ho
- Department of Cell Biology and Human Anatomy, University of California, Davis School of MedicineDavisUnited States
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Tehranchinia Z, Abdollahimajd F, Haghighatkhah H, Talebi A, Yarahmadi A, Zoghi G. The frequency of fatty liver in patients with alopecia areata: A case-control study. J Cosmet Dermatol 2023; 22:2579-2583. [PMID: 37017934 DOI: 10.1111/jocd.15754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 02/03/2023] [Accepted: 03/21/2023] [Indexed: 04/06/2023]
Abstract
BACKGROUND Alopecia areata (AA) is an immune-mediated nonscarring hair loss disorder with multiple subtypes, including alopecia universalis (AU). Previous studies have shown a link between serum lipid profile and alopecia. We aimed to investigate the frequency of fatty liver in patients with AU and patchy alopecia areata (PAA) compared to a control group. METHODS This case-control study included patients with AU and PAA referred to a dermatology clinic from September 23, 2019 to September 23, 2020. A group of individuals without hair loss disorders attending the same clinic were selected as controls. Participants' general information, including age, sex, weight, height, and waist circumference (WC), was recorded. Body mass index (BMI) was calculated for all participants. Also, hyperlipidemia and statin use were noted and liver enzymes were evaluated. For AU and PAA patients, disease duration and the Severity of Alopecia Tool (SALT) score were also recorded. Then, all subjects underwent ultrasound to assess fatty liver and its grade. RESULTS Overall, 32 patients were included in each group. All three groups were comparable in age, sex, weight, height, BMI, WC, hyperlipidemia, abnormal liver enzymes, and statin use. Disease duration and SALT score were significantly higher in the AU than in the PAA group (p = 0.009 and p < 0.001, respectively). The frequency of fatty liver was the highest in AU patients (40.6%), followed by 34.4% in PAA patients, and 21.9% in controls (p = 0.263). This was also the case for grade-1 fatty liver, while grade-2 was more common in PAA patients, and grade-3 was only observed in one patient from the AU group (p = 0.496). CONCLUSIONS Fatty liver was more frequent in AU and PAA patients than controls, without statistically significant differences. There might be an association between fatty liver and AA, particularly the AU subtype.
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Affiliation(s)
- Zohreh Tehranchinia
- Skin Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Fahimeh Abdollahimajd
- Department of Dermatology, Shohada-e-Tajrish Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hamidreza Haghighatkhah
- Radiology Department of Diagnosis Imaging, Shohada-e-Tajrish Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Atefeh Talebi
- Colorectal Research Center, Rasool Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - Amin Yarahmadi
- Skin Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ghazal Zoghi
- Endocrinology and Metabolism Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
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Abstract
Ligands of the Hedgehog (HH) pathway are paracrine signaling molecules that coordinate tissue development in metazoans. A remarkable feature of HH signaling is the repeated use of cholesterol in steps spanning ligand biogenesis, secretion, dispersal, and reception on target cells. A cholesterol molecule covalently attached to HH ligands is used as a molecular baton by transfer proteins to guide their secretion, spread, and reception. On target cells, a signaling circuit composed of a cholesterol transporter and sensor regulates transmission of HH signals across the plasma membrane to the cytoplasm. The repeated use of cholesterol in signaling supports the view that the HH pathway likely evolved by coopting ancient systems to regulate the abundance or organization of sterol-like lipids in membranes.
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Affiliation(s)
- Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom;
| | - Rajat Rohatgi
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, California, USA;
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Kantaputra P, Jatooratthawichot P, Tantachamroon O, Nanekrungsan K, Intachai W, Olsen B, Tongsima S, Ngamphiw C, Cairns JRK. Novel Dental Anomaly-associated Mutations in WNT10A Protein Binding Sites. Int Dent J 2022; 73:79-86. [PMID: 35537890 PMCID: PMC9875279 DOI: 10.1016/j.identj.2022.04.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 04/06/2022] [Indexed: 01/28/2023] Open
Abstract
OBJECTIVE WNT/β-catenin signaling is initiated by binding of a WNT protein to a Frizzled (FZD) receptor and a co-receptor, low-density lipoprotein (LDL) receptor-related protein 5 or 6 (LRP5/6). The objective of this study was to find the genetic variants responsible for dental anomalies found in 4 families. METHODS Clinical and radiographic examination and whole exome sequencing were performed on 5 patients affected with dental anomalies and the mutant proteins modeled. RESULTS Five patients were heterozygous for the WNT10A variants, including c.877C>T; p.Arg293Cys, c.874A>G; p.Ser292Gly, c.1042C>T; p.Arg348Cys, and c.1039G>T; p.347GluX. The p.Arg293Cys and p.Ser292Gly mutations are located in the WNT10A N-terminal domain region with binding sites for FZD receptor, porcupine, WNTLESS, and extracellular binding proteins, so they are likely to have adverse effects on binding these proteins. The p.Arg348Cys mutation, which is located in the binding site of LRP5/6 co-receptors, is postulated to result in impaired binding to these co-receptors. The nonsense mutation p.347GluX is predicted to result in the truncation of most of the C-terminal domain, which is likely to disrupt the binding of WNT10A to WNTLESS, the membrane protein that binds lipid-acylated WNT proteins to carry them from the endoplasmic reticulum to the cell surface and FZD. CONCLUSIONS Four novel mutations in WNT10A were identified in patients with isolated tooth agenesis. The mutations in the N-terminal domain and the interface between the N- and C-terminal domains of WNT10A in our patients are likely to disrupt its binding with FZD, LRP5/6, and various other proteins involved in WNT10A processing and transport, impair WNT and SHH signaling, and subsequently result in tooth agenesis, microdontia, and root maldevelopment.
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Affiliation(s)
- Piranit Kantaputra
- Center of Excellence in Medical Genetics Research, Chiang Mai University, Chiang Mai, Thailand,Division of Pediatric Dentistry, Department of Orthodontics and Pediatric Dentistry, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand,Corresponding author. Division of Pediatric Dentistry, Department of Orthodontics and Pediatric Dentistry; Faculty of Dentistry, Chiang Mai University; Chiang Mai 50200, Thailand.
| | - Peeranat Jatooratthawichot
- School of Chemistry, Institute of Science, and Center for Biomolecular Structure, Function and Application, Suranaree University of Technology, Nakhon Ratchasima, Thailand
| | | | | | - Worrachet Intachai
- Center of Excellence in Medical Genetics Research, Chiang Mai University, Chiang Mai, Thailand
| | - Bjorn Olsen
- Department of Developmental Biology, Harvard School of Dental Medicine, Harvard University, Boston, Massachusetts, USA
| | - Sissades Tongsima
- National Biobank of Thailand, National Science and Technology Development Agency (NSTDA), Thailand Science Park, Pathum Thani, Thailand
| | - Chumpol Ngamphiw
- National Biobank of Thailand, National Science and Technology Development Agency (NSTDA), Thailand Science Park, Pathum Thani, Thailand
| | - James R. Ketudat Cairns
- School of Chemistry, Institute of Science, and Center for Biomolecular Structure, Function and Application, Suranaree University of Technology, Nakhon Ratchasima, Thailand,Laboratory of Biochemistry, Chulabhorn Research Institute, Bangkok, Thailand
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Daggubati V, Raleigh DR, Sever N. Sterol regulation of developmental and oncogenic Hedgehog signaling. Biochem Pharmacol 2022; 196:114647. [PMID: 34111427 PMCID: PMC8648856 DOI: 10.1016/j.bcp.2021.114647] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 06/02/2021] [Accepted: 06/04/2021] [Indexed: 02/03/2023]
Abstract
The Hedgehog (Hh) family of lipid-modified signaling proteins directs embryonic tissue patterning and postembryonic tissue homeostasis, and dysregulated Hh signaling drives familial and sporadic cancers. Hh ligands bind to and inhibit the tumor suppressor Patched and allow the oncoprotein Smoothened (SMO) to accumulate in cilia, which in turn activates the GLI family of transcription factors. Recent work has demonstrated that endogenous cholesterol and oxidized cholesterol derivatives (oxysterols) bind and modulate SMO activity. Here we discuss the myriad sterols that activate or inhibit the Hh pathway, with emphasis on endogenous 24(S),25-epoxycholesterol and 3β,5α-dihydroxycholest-7-en-6-one, and propose models of sterol regulation of SMO. Synthetic inhibitors of SMO have long been the focus of drug development efforts. Here, we discuss the possible utility of steroidal SMO ligands or inhibitors of enzymes involved in sterol metabolism as cancer therapeutics.
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Affiliation(s)
- Vikas Daggubati
- Departments of Radiation Oncology and Neurological Surgery, and Biomedical Sciences Graduate Program, University of California, San Francisco, CA, USA,Medical Scientist Training Program, University of California, San Francisco, CA, USA
| | - David R. Raleigh
- Departments of Radiation Oncology and Neurological Surgery, and Biomedical Sciences Graduate Program, University of California, San Francisco, CA, USA
| | - Navdar Sever
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA,Corresponding author: Navdar Sever, Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, LHRRB 405, Boston, MA 02115, USA, , Telephone: (617) 432-1612
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6
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Griffiths SC, Schwab RA, El Omari K, Bishop B, Iverson EJ, Malinauskas T, Dubey R, Qian M, Covey DF, Gilbert RJC, Rohatgi R, Siebold C. Hedgehog-Interacting Protein is a multimodal antagonist of Hedgehog signalling. Nat Commun 2021; 12:7171. [PMID: 34887403 PMCID: PMC8660895 DOI: 10.1038/s41467-021-27475-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 11/19/2021] [Indexed: 01/20/2023] Open
Abstract
Hedgehog (HH) morphogen signalling, crucial for cell growth and tissue patterning in animals, is initiated by the binding of dually lipidated HH ligands to cell surface receptors. Hedgehog-Interacting Protein (HHIP), the only reported secreted inhibitor of Sonic Hedgehog (SHH) signalling, binds directly to SHH with high nanomolar affinity, sequestering SHH. Here, we report the structure of the HHIP N-terminal domain (HHIP-N) in complex with a glycosaminoglycan (GAG). HHIP-N displays a unique bipartite fold with a GAG-binding domain alongside a Cysteine Rich Domain (CRD). We show that HHIP-N is required to convey full HHIP inhibitory function, likely by interacting with the cholesterol moiety covalently linked to HH ligands, thereby preventing this SHH-attached cholesterol from binding to the HH receptor Patched (PTCH1). We also present the structure of the HHIP C-terminal domain in complex with the GAG heparin. Heparin can bind to both HHIP-N and HHIP-C, thereby inducing clustering at the cell surface and generating a high-avidity platform for SHH sequestration and inhibition. Our data suggest a multimodal mechanism, in which HHIP can bind two specific sites on the SHH morphogen, alongside multiple GAG interactions, to inhibit SHH signalling.
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Affiliation(s)
- Samuel C Griffiths
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
- Evotec (UK) Ltd., Milton Park, Abingdon, UK
| | - Rebekka A Schwab
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Kamel El Omari
- Science Division, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Benjamin Bishop
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Ellen J Iverson
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Tomas Malinauskas
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Ramin Dubey
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Mingxing Qian
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MI, USA
| | - Douglas F Covey
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MI, USA
| | - Robert J C Gilbert
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Rajat Rohatgi
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.
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7
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Radhakrishnan A, Rohatgi R, Siebold C. Cholesterol access in cellular membranes controls Hedgehog signaling. Nat Chem Biol 2020; 16:1303-1313. [PMID: 33199907 PMCID: PMC7872078 DOI: 10.1038/s41589-020-00678-2] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 09/18/2020] [Indexed: 12/11/2022]
Abstract
The Hedgehog (Hh) signaling pathway coordinates cell-cell communication in development and regeneration. Defects in this pathway underlie diseases ranging from birth defects to cancer. Hh signals are transmitted across the plasma membrane by two proteins, Patched 1 (PTCH1) and Smoothened (SMO). PTCH1, a transporter-like tumor-suppressor protein, binds to Hh ligands, but SMO, a G-protein-coupled-receptor family oncoprotein, transmits the Hh signal across the membrane. Recent structural, biochemical and cell-biological studies have converged at the surprising model that a specific pool of plasma membrane cholesterol, termed accessible cholesterol, functions as a second messenger that conveys the signal between PTCH1 and SMO. Beyond solving a central puzzle in Hh signaling, these studies are revealing new principles in membrane biology: how proteins respond to and remodel cholesterol accessibility in membranes and how the cholesterol composition of organelle membranes is used to regulate protein function.
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Affiliation(s)
- Arun Radhakrishnan
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Rajat Rohatgi
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, CA, USA.
| | - Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.
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8
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Disorders of FZ-CRD; insights towards FZ-CRD folding and therapeutic landscape. Mol Med 2019; 26:4. [PMID: 31892318 PMCID: PMC6938638 DOI: 10.1186/s10020-019-0129-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Accepted: 12/13/2019] [Indexed: 02/08/2023] Open
Abstract
The ER is hub for protein folding. Proteins that harbor a Frizzled cysteine-rich domain (FZ-CRD) possess 10 conserved cysteine motifs held by a unique disulfide bridge pattern which attains a correct fold in the ER. Little is known about implications of disease-causing missense mutations within FZ-CRD families. Mutations in FZ-CRD of Frizzled class receptor 4 (FZD4) and Muscle, skeletal, receptor tyrosine kinase (MuSK) and Receptor tyrosine kinase-like orphan receptor 2 (ROR2) cause Familial Exudative Vitreoretinopathy (FEVR), Congenital Myasthenic Syndrome (CMS), and Robinow Syndrome (RS) respectively. We highlight reported pathogenic inherited missense mutations in FZ-CRD of FZD4, MuSK and ROR2 which misfold, and traffic abnormally in the ER, with ER-associated degradation (ERAD) as a common pathogenic mechanism for disease. Our review shows that all studied FZ-CRD mutants of RS, FEVR and CMS result in misfolded proteins and/or partially misfolded proteins with an ERAD fate, thus we coin them as “disorders of FZ-CRD”. Abnormal trafficking was demonstrated in 17 of 29 mutants studied; 16 mutants were within and/or surrounding the FZ-CRD with two mutants distant from FZ-CRD. These ER-retained mutants were improperly N-glycosylated confirming ER-localization. FZD4 and MuSK mutants were tagged with polyubiquitin chains confirming targeting for proteasomal degradation. Investigating the cellular and molecular mechanisms of these mutations is important since misfolded protein and ER-targeted therapies are in development. The P344R-MuSK kinase mutant showed around 50% of its in-vitro autophosphorylation activity and P344R-MuSK increased two-fold on proteasome inhibition. M105T-FZD4, C204Y-FZD4, and P344R-MuSK mutants are thermosensitive and therefore, might benefit from extending the investigation to a larger number of chemical chaperones and/or proteasome inhibitors. Nonetheless, FZ-CRD ER-lipidation it less characterized in the literature and recent structural data sheds light on the importance of lipidation in protein glycosylation, proper folding, and ER trafficking. Current treatment strategies in-place for the conformational disease landscape is highlighted. From this review, we envision that disorders of FZ-CRD might be receptive to therapies that target FZ-CRD misfolding, regulation of fatty acids, and/or ER therapies; thus paving the way for a newly explored paradigm to treat different diseases with common defects.
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9
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Rudolf AF, Kinnebrew M, Kowatsch C, Ansell TB, El Omari K, Bishop B, Pardon E, Schwab RA, Malinauskas T, Qian M, Duman R, Covey DF, Steyaert J, Wagner A, Sansom MSP, Rohatgi R, Siebold C. The morphogen Sonic hedgehog inhibits its receptor Patched by a pincer grasp mechanism. Nat Chem Biol 2019; 15:975-982. [PMID: 31548691 PMCID: PMC6764859 DOI: 10.1038/s41589-019-0370-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 07/25/2019] [Indexed: 12/29/2022]
Abstract
Hedgehog (HH) ligands, classical morphogens that pattern embryonic tissues in all animals, are covalently coupled to two lipids-a palmitoyl group at the N terminus and a cholesteroyl group at the C terminus. While the palmitoyl group binds and inactivates Patched 1 (PTCH1), the main receptor for HH ligands, the function of the cholesterol modification has remained mysterious. Using structural and biochemical studies, along with reassessment of previous cryo-electron microscopy structures, we find that the C-terminal cholesterol attached to Sonic hedgehog (Shh) binds the first extracellular domain of PTCH1 and promotes its inactivation, thus triggering HH signaling. Molecular dynamics simulations show that this interaction leads to the closure of a tunnel through PTCH1 that serves as the putative conduit for sterol transport. Thus, Shh inactivates PTCH1 by grasping its extracellular domain with two lipidic pincers, the N-terminal palmitate and the C-terminal cholesterol, which are both inserted into the PTCH1 protein core.
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Affiliation(s)
- Amalie F Rudolf
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Maia Kinnebrew
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Christiane Kowatsch
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - T Bertie Ansell
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Kamel El Omari
- Science Division, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Benjamin Bishop
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Els Pardon
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Rebekka A Schwab
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Tomas Malinauskas
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Mingxing Qian
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Ramona Duman
- Science Division, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Douglas F Covey
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Armin Wagner
- Science Division, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Rajat Rohatgi
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, CA, USA.
| | - Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.
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10
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Kowatsch C, Woolley RE, Kinnebrew M, Rohatgi R, Siebold C. Structures of vertebrate Patched and Smoothened reveal intimate links between cholesterol and Hedgehog signalling. Curr Opin Struct Biol 2019; 57:204-214. [PMID: 31247512 PMCID: PMC6744280 DOI: 10.1016/j.sbi.2019.05.015] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 05/16/2019] [Accepted: 05/18/2019] [Indexed: 12/21/2022]
Abstract
The Hedgehog (HH) signalling pathway is a cell-cell communication system that controls the patterning of multiple tissues during embryogenesis in metazoans. In adults, HH signals regulate tissue stem cells and regenerative responses. Abnormal signalling can cause birth defects and cancer. The HH signal is received on target cells by Patched (PTCH1), the receptor for HH ligands, and then transmitted across the plasma membrane by Smoothened (SMO). Recent structural and biochemical studies have pointed to a sterol lipid, likely cholesterol itself, as the elusive second messenger that communicates the HH signal between PTCH1 and SMO, thus linking ligand reception to transmembrane signalling.
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Affiliation(s)
- Christiane Kowatsch
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Rachel E Woolley
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Maia Kinnebrew
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, CA, United States
| | - Rajat Rohatgi
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, CA, United States.
| | - Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.
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11
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Abstract
Signaling pathways that mediate cell-cell communication are essential for collective cell behaviors in multicellular systems. The hedgehog (HH) pathway, first discovered and elucidated in Drosophila, is one of these iconic signaling systems that plays many roles during embryogenesis and in adults; abnormal HH signaling can lead to birth defects and cancer. We review recent structural and biochemical studies that have advanced our understanding of the vertebrate HH pathway, focusing on the mechanisms by which the HH signal is received by patched on target cells, transduced across the cell membrane by smoothened, and transmitted to the nucleus by GLI proteins to influence gene-expression programs.
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Affiliation(s)
- Jennifer H Kong
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Rajat Rohatgi
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
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12
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Byrne EF, Luchetti G, Rohatgi R, Siebold C. Multiple ligand binding sites regulate the Hedgehog signal transducer Smoothened in vertebrates. Curr Opin Cell Biol 2018; 51:81-88. [PMID: 29268141 PMCID: PMC5949240 DOI: 10.1016/j.ceb.2017.10.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 10/16/2017] [Indexed: 12/31/2022]
Abstract
The Hedgehog (Hh) pathway plays a central role in the development of multicellular organisms, guiding cell differentiation, proliferation and survival. While many components of the vertebrate pathway were discovered two decades ago, the mechanism by which the Hh signal is transmitted across the plasma membrane remains mysterious. This fundamental task in signalling is carried out by Smoothened (SMO), a human oncoprotein and validated cancer drug target that is a member of the G-protein coupled receptor protein family. Recent structural and functional studies have advanced our mechanistic understanding of SMO activation, revealing its unique regulation by two separable but allosterically-linked ligand-binding sites. Unexpectedly, these studies have nominated cellular cholesterol as having an instructive role in SMO signalling.
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Affiliation(s)
- Eamon Fx Byrne
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Giovanni Luchetti
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, CA, United States
| | - Rajat Rohatgi
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, CA, United States.
| | - Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.
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13
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Mukhopadhyay S, Badgandi HB, Hwang SH, Somatilaka B, Shimada IS, Pal K. Trafficking to the primary cilium membrane. Mol Biol Cell 2017; 28:233-239. [PMID: 28082521 PMCID: PMC5231892 DOI: 10.1091/mbc.e16-07-0505] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 11/14/2016] [Accepted: 11/15/2016] [Indexed: 12/13/2022] Open
Abstract
The primary cilium has been found to be associated with a number of cellular signaling pathways, such as vertebrate hedgehog signaling, and implicated in the pathogenesis of diseases affecting multiple organs, including the neural tube, kidney, and brain. The primary cilium is the site where a subset of the cell's membrane proteins is enriched. However, pathways that target and concentrate membrane proteins in cilia are not well understood. Processes determining the level of proteins in the ciliary membrane include entry into the compartment, removal, and retention by diffusion barriers such as the transition zone. Proteins that are concentrated in the ciliary membrane are also localized to other cellular sites. Thus it is critical to determine the particular role for ciliary compartmentalization in sensory reception and signaling pathways. Here we provide a brief overview of our current understanding of compartmentalization of proteins in the ciliary membrane and the dynamics of trafficking into and out of the cilium. We also discuss major unanswered questions regarding the role that defects in ciliary compartmentalization might play in disease pathogenesis. Understanding the trafficking mechanisms that underlie the role of ciliary compartmentalization in signaling might provide unique approaches for intervention in progressive ciliopathies.
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Affiliation(s)
- Saikat Mukhopadhyay
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390
| | - Hemant B Badgandi
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390
| | - Sun-Hee Hwang
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390
| | | | - Issei S Shimada
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390
| | - Kasturi Pal
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390
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14
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Griffiths WJ, Abdel-Khalik J, Yutuc E, Morgan AH, Gilmore I, Hearn T, Wang Y. Cholesterolomics: An update. Anal Biochem 2017; 524:56-67. [PMID: 28087213 PMCID: PMC5378159 DOI: 10.1016/j.ab.2017.01.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 12/23/2016] [Accepted: 01/09/2017] [Indexed: 01/04/2023]
Abstract
Cholesterolomics can be regarded as the identification and quantification of cholesterol, its precursors post squalene, and metabolites of cholesterol and of its precursors, in a biological sample. These molecules include 1,25-dihydroxyvitamin D3, steroid hormones and bile acids and intermediates in their respective biosynthetic pathways. In this short article we will concentrate our attention on intermediates in bile acid biosynthesis pathways, in particular oxysterols and cholestenoic acids. These molecular classes are implicated in the aetiology of a diverse array of diseases including autoimmune disease, Parkinson's disease, motor neuron disease, breast cancer, the lysosomal storage disease Niemann-Pick type C and the autosomal recessive disorder Smith-Lemli-Opitz syndrome. Mass spectrometry (MS) is the dominant technology for sterol analysis including both gas-chromatography (GC)-MS and liquid chromatography (LC)-MS and more recently matrix-assisted laser desorption/ionisation (MALDI)-MS for tissue imaging studies. Here we will discuss exciting biological findings and recent analytical improvements.
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Affiliation(s)
| | | | - Eylan Yutuc
- Swansea University Medical School, Singleton Park, Swansea SA2 8PP, UK
| | - Alwena H Morgan
- Swansea University Medical School, Singleton Park, Swansea SA2 8PP, UK
| | - Ian Gilmore
- Swansea University Medical School, Singleton Park, Swansea SA2 8PP, UK
| | - Thomas Hearn
- Swansea University Medical School, Singleton Park, Swansea SA2 8PP, UK
| | - Yuqin Wang
- Swansea University Medical School, Singleton Park, Swansea SA2 8PP, UK.
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15
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Sharpe H. A new trick for an old lipid. eLife 2016; 5. [PMID: 27885984 PMCID: PMC5123860 DOI: 10.7554/elife.22492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 11/22/2016] [Indexed: 11/16/2022] Open
Abstract
Cholesterol can regulate the Hedgehog signalling pathway by directly binding to a receptor on the cell surface.
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Affiliation(s)
- Hayley Sharpe
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
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16
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Luchetti G, Sircar R, Kong JH, Nachtergaele S, Sagner A, Byrne EFX, Covey DF, Siebold C, Rohatgi R. Cholesterol activates the G-protein coupled receptor Smoothened to promote Hedgehog signaling. eLife 2016; 5:e20304. [PMID: 27705744 PMCID: PMC5123864 DOI: 10.7554/elife.20304] [Citation(s) in RCA: 174] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 10/03/2016] [Indexed: 12/12/2022] Open
Abstract
Cholesterol is necessary for the function of many G-protein coupled receptors (GPCRs). We find that cholesterol is not just necessary but also sufficient to activate signaling by the Hedgehog (Hh) pathway, a prominent cell-cell communication system in development. Cholesterol influences Hh signaling by directly activating Smoothened (SMO), an orphan GPCR that transmits the Hh signal across the membrane in all animals. Unlike many GPCRs, which are regulated by cholesterol through their heptahelical transmembrane domains, SMO is activated by cholesterol through its extracellular cysteine-rich domain (CRD). Residues shown to mediate cholesterol binding to the CRD in a recent structural analysis also dictate SMO activation, both in response to cholesterol and to native Hh ligands. Our results show that cholesterol can initiate signaling from the cell surface by engaging the extracellular domain of a GPCR and suggest that SMO activity may be regulated by local changes in cholesterol abundance or accessibility.
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Affiliation(s)
- Giovanni Luchetti
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
- Department of Medicine, Stanford University School of Medicine, Stanford, United States
| | - Ria Sircar
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
- Department of Medicine, Stanford University School of Medicine, Stanford, United States
| | - Jennifer H Kong
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
- Department of Medicine, Stanford University School of Medicine, Stanford, United States
| | - Sigrid Nachtergaele
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
- Department of Medicine, Stanford University School of Medicine, Stanford, United States
| | - Andreas Sagner
- Mill Hill Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Eamon FX Byrne
- Division of Structural Biology, University of Oxford, Oxford, United Kingdom
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Douglas F Covey
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, United States
| | - Christian Siebold
- Division of Structural Biology, University of Oxford, Oxford, United Kingdom
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Rajat Rohatgi
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
- Department of Medicine, Stanford University School of Medicine, Stanford, United States
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17
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Huang P, Nedelcu D, Watanabe M, Jao C, Kim Y, Liu J, Salic A. Cellular Cholesterol Directly Activates Smoothened in Hedgehog Signaling. Cell 2016; 166:1176-1187.e14. [PMID: 27545348 DOI: 10.1016/j.cell.2016.08.003] [Citation(s) in RCA: 268] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Revised: 06/14/2016] [Accepted: 07/30/2016] [Indexed: 12/28/2022]
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.
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Affiliation(s)
- Pengxiang Huang
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Daniel Nedelcu
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Miyako Watanabe
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Cindy Jao
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Youngchang Kim
- Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Jing Liu
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Adrian Salic
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
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18
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Byrne EF, Sircar R, Miller PS, Hedger G, Luchetti G, Nachtergaele S, Tully MD, Mydock-McGrane L, Covey DF, Rambo RP, Sansom MSP, Newstead S, Rohatgi R, Siebold C. Structural basis of Smoothened regulation by its extracellular domains. Nature 2016; 535:517-522. [PMID: 27437577 PMCID: PMC4970916 DOI: 10.1038/nature18934] [Citation(s) in RCA: 254] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 06/15/2016] [Indexed: 01/04/2023]
Abstract
Developmental signals of the Hedgehog (Hh) and Wnt families are transduced across the membrane by Frizzledclass G-protein-coupled receptors (GPCRs) composed of both a heptahelical transmembrane domain (TMD) and an extracellular cysteine-rich domain (CRD). How the large extracellular domains of GPCRs regulate signalling by the TMD is unknown. We present crystal structures of the Hh signal transducer and oncoprotein Smoothened, a GPCR that contains two distinct ligand-binding sites: one in its TMD and one in the CRD. The CRD is stacked a top the TMD, separated by an intervening wedge-like linker domain. Structure-guided mutations show that the interface between the CRD, linker domain and TMD stabilizes the inactive state of Smoothened. Unexpectedly, we find a cholesterol molecule bound to Smoothened in the CRD binding site. Mutations predicted to prevent cholesterol binding impair the ability of Smoothened to transmit native Hh signals. Binding of a clinically used antagonist, vismodegib, to the TMD induces a conformational change that is propagated to the CRD, resulting in loss of cholesterol from the CRD-linker domain-TMD interface. Our results clarify the structural mechanism by which the activity of a GPCR is controlled by ligand-regulated interactions between its extracellular and transmembrane domains.
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Affiliation(s)
- Eamon F.X. Byrne
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Ria Sircar
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, California, United States of America
| | - Paul S. Miller
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - George Hedger
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Giovanni Luchetti
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, California, United States of America
| | - Sigrid Nachtergaele
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, California, United States of America
| | - Mark D. Tully
- Diamond Light Source Ltd, Harwell Science &Innovation Campus, Didcot, UK
| | - Laurel Mydock-McGrane
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Douglas F. Covey
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Robert P. Rambo
- Diamond Light Source Ltd, Harwell Science &Innovation Campus, Didcot, UK
| | | | - Simon Newstead
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Rajat Rohatgi
- Departments of Biochemistry and Medicine, Stanford University School of Medicine, Stanford, California, United States of America
| | - Christian Siebold
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
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19
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Kaemmerer E, Gassler N. Wnt Lipidation and Modifiers in Intestinal Carcinogenesis and Cancer. Cancers (Basel) 2016; 8:E69. [PMID: 27438855 PMCID: PMC4963811 DOI: 10.3390/cancers8070069] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 07/14/2016] [Accepted: 07/14/2016] [Indexed: 12/16/2022] Open
Abstract
The wingless (Wnt) signaling is suggested as a fundamental hierarchical pathway in regulation of proliferation and differentiation of cells. The Wnt ligands are small proteins of about 40 kDa essentially for regulation and initiation of the Wnt activity. They are secreted proteins requiring acylation for activity in the Wnt signaling cascade and for functional interactivity with transmembrane proteins. Dual lipidation is important for posttranslational activation of the overwhelming number of Wnt proteins and is probably involved in their spatial distribution. The intestinal mucosa, where Wnt signaling is essential in configuration and maintenance, is an established model to study Wnt proteins and their role in carcinogenesis and cancer. The intestinal crypt-villus/crypt-plateau axis, a cellular system with self-renewal, proliferation, and differentiation, is tightly coordinated by a Wnt gradient. In the review, some attention is given to Wnt3, Wnt3A, and Wnt2B as important members of the Wnt family to address the role of lipidation and modifiers of Wnt proteins in intestinal carcinogenesis. Wnt3 is an important player in establishing the Wnt gradient in intestinal crypts and is mainly produced by Paneth cells. Wnt2B is characterized as a mitochondrial protein and shuttles between mitochondria and the nucleus. Porcupine and ACSL5, a long-chain fatty acid activating enzyme, are introduced as modifiers of Wnts and as interesting strategy to targeting Wnt-driven carcinogenesis.
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Affiliation(s)
- Elke Kaemmerer
- Institute of Pathology, RWTH Aachen University, Aachen 52074, Germany.
- Department of Pediatrics, RWTH Aachen University, Aachen 52074, Germany.
| | - Nikolaus Gassler
- Institute of Pathology, RWTH Aachen University, Aachen 52074, Germany.
- Institute of Pathology, Klinikum Braunschweig, Braunschweig 38114, Germany.
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20
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Regulation of the oncoprotein Smoothened by small molecules. Nat Chem Biol 2015; 11:246-55. [PMID: 25785427 DOI: 10.1038/nchembio.1776] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 02/19/2015] [Indexed: 01/01/2023]
Abstract
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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21
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McCabe JM, Leahy DJ. Smoothened goes molecular: new pieces in the hedgehog signaling puzzle. J Biol Chem 2014; 290:3500-7. [PMID: 25519909 DOI: 10.1074/jbc.r114.617936] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
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.
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Affiliation(s)
- Jacqueline M McCabe
- From the Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Daniel J Leahy
- From the Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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22
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Cheng H, Schaeffer RD, Liao Y, Kinch LN, Pei J, Shi S, Kim BH, Grishin NV. ECOD: an evolutionary classification of protein domains. PLoS Comput Biol 2014; 10:e1003926. [PMID: 25474468 PMCID: PMC4256011 DOI: 10.1371/journal.pcbi.1003926] [Citation(s) in RCA: 225] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 09/22/2014] [Indexed: 01/02/2023] Open
Abstract
Understanding the evolution of a protein, including both close and distant relationships, often reveals insight into its structure and function. Fast and easy access to such up-to-date information facilitates research. We have developed a hierarchical evolutionary classification of all proteins with experimentally determined spatial structures, and presented it as an interactive and updatable online database. ECOD (Evolutionary Classification of protein Domains) is distinct from other structural classifications in that it groups domains primarily by evolutionary relationships (homology), rather than topology (or "fold"). This distinction highlights cases of homology between domains of differing topology to aid in understanding of protein structure evolution. ECOD uniquely emphasizes distantly related homologs that are difficult to detect, and thus catalogs the largest number of evolutionary links among structural domain classifications. Placing distant homologs together underscores the ancestral similarities of these proteins and draws attention to the most important regions of sequence and structure, as well as conserved functional sites. ECOD also recognizes closer sequence-based relationships between protein domains. Currently, approximately 100,000 protein structures are classified in ECOD into 9,000 sequence families clustered into close to 2,000 evolutionary groups. The classification is assisted by an automated pipeline that quickly and consistently classifies weekly releases of PDB structures and allows for continual updates. This synchronization with PDB uniquely distinguishes ECOD among all protein classifications. Finally, we present several case studies of homologous proteins not recorded in other classifications, illustrating the potential of how ECOD can be used to further biological and evolutionary studies.
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Affiliation(s)
- Hua Cheng
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - R. Dustin Schaeffer
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Yuxing Liao
- Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Lisa N. Kinch
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Jimin Pei
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Shuoyong Shi
- Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Bong-Hyun Kim
- Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Nick V. Grishin
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- * E-mail:
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23
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Malinauskas T, Jones EY. Extracellular modulators of Wnt signalling. Curr Opin Struct Biol 2014; 29:77-84. [PMID: 25460271 DOI: 10.1016/j.sbi.2014.10.003] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 09/26/2014] [Accepted: 10/02/2014] [Indexed: 10/24/2022]
Abstract
Wnt morphogens are secreted signalling proteins that play leading roles in embryogenesis and tissue homeostasis throughout life. Wnt signalling is controlled by multiple mechanisms, including posttranslational modification of Wnts, antagonist binding (to Wnts or their receptors), and regulation of the availability of Wnt receptors. Recent crystallographic, structure-guided biophysical and cell-based studies have advanced our understanding of how Wnt signalling is regulated at the cell surface. Structures include Wnt in complex with the cysteine-rich domain (CRD) of Frizzled, extracellular fragments of Wnt co-receptor LRP6, LRP6-binding antagonists Dickkopf and Sclerostin, antagonists 5T4/WAIF1 and Wnt inhibitory factor 1 (WIF-1), as well as Frizzled-ubiquitin ligases ZNRF3/RNF43 (in isolation and in complexes with Wnt signalling promoters R-spondins and LGR5). We review recent discoveries and remaining questions.
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Affiliation(s)
- Tomas Malinauskas
- Cold Spring Harbor Laboratory, W. M. Keck Structural Biology Laboratory, Cold Spring Harbor, NY 11724, USA
| | - E Yvonne Jones
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom.
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24
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Nachtergaele S, Whalen DM, Mydock LK, Zhao Z, Malinauskas T, Krishnan K, Ingham PW, Covey DF, Siebold C, Rohatgi R. Structure and function of the Smoothened extracellular domain in vertebrate Hedgehog signaling. eLife 2013; 2:e01340. [PMID: 24171105 PMCID: PMC3809587 DOI: 10.7554/elife.01340] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 09/26/2013] [Indexed: 12/14/2022] Open
Abstract
The Hedgehog (Hh) signal is transduced across the membrane by the heptahelical protein Smoothened (Smo), a developmental regulator, oncoprotein and drug target in oncology. We present the 2.3 Å crystal structure of the extracellular cysteine rich domain (CRD) of vertebrate Smo and show that it binds to oxysterols, endogenous lipids that activate Hh signaling. The oxysterol-binding groove in the Smo CRD is analogous to that used by Frizzled 8 to bind to the palmitoleyl group of Wnt ligands and to similar pockets used by other Frizzled-like CRDs to bind hydrophobic ligands. The CRD is required for signaling in response to native Hh ligands, showing that it is an important regulatory module for Smo activation. Indeed, targeting of the Smo CRD by oxysterol-inspired small molecules can block signaling by all known classes of Hh activators and by clinically relevant Smo mutants. DOI:http://dx.doi.org/10.7554/eLife.01340.001.
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MESH Headings
- Animals
- Binding Sites
- Crystallography, X-Ray
- Embryo, Nonmammalian
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Gene Expression Regulation, Developmental
- Hedgehog Proteins/chemistry
- Hedgehog Proteins/genetics
- Hedgehog Proteins/metabolism
- Ligands
- Mice
- Models, Molecular
- Protein Binding
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Receptors, G-Protein-Coupled/antagonists & inhibitors
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Signal Transduction
- Smoothened Receptor
- Sterols/chemistry
- Structure-Activity Relationship
- Zebrafish/genetics
- Zebrafish/growth & development
- Zebrafish/metabolism
- Zebrafish Proteins/antagonists & inhibitors
- Zebrafish Proteins/chemistry
- Zebrafish Proteins/genetics
- Zebrafish Proteins/metabolism
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Affiliation(s)
- Sigrid Nachtergaele
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
| | - Daniel M Whalen
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Laurel K Mydock
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, United States
| | - Zhonghua Zhao
- A*STAR Institute of Molecular and Cell Biology, Singapore, Singapore
| | - Tomas Malinauskas
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Kathiresan Krishnan
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, United States
| | - Philip W Ingham
- A*STAR Institute of Molecular and Cell Biology, Singapore, Singapore
- Lee Kong Chian School of Medicine, Imperial College London/Nanyang Technological University, Singapore, Singapore
| | - Douglas F Covey
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, United States
| | - Christian Siebold
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Rajat Rohatgi
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
- Department of Medicine, Stanford University School of Medicine, Stanford, United States
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25
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Pons T, Paramonov I, Boullosa C, Ibáñez K, Rojas AM, Valencia A. A common structural scaffold in CTD phosphatases that supports distinct catalytic mechanisms. Proteins 2013; 82:103-18. [PMID: 23900790 DOI: 10.1002/prot.24376] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 06/28/2013] [Accepted: 07/12/2013] [Indexed: 01/01/2023]
Abstract
The phosphorylation and dephosphorylation of the carboxyl-terminal domain (CTD) of the largest RNA polymerase II (RNAPII) subunit is a critical regulatory checkpoint for transcription and mRNA processing. This CTD is unique to eukaryotic organisms and it contains multiple tandem-repeats with the consensus sequence Tyr(1) -Ser(2) -Pro(3) -Thr(4) -Ser(5) -Pro(6) -Ser(7) . Traditionally, CTD phosphatases that use metal-ion-independent (cysteine-based) and metal-ion-assisted (aspartate-based) catalytic mechanisms have been considered to belong to two independent groups. However, using structural comparisons we have identified a common structural scaffold in these two groups of CTD phosphatases. This common scaffold accommodates different catalytic processes with the same substrate specificity, in this case phospho-serine/threonine residues flanked by prolines. Furthermore, this scaffold provides a structural connection between two groups of protein tyrosine phosphatases (PTPs): Cys-based (classes I, II, and III) and Asp-based (class IV) PTPs. Redundancy in catalytic mechanisms is not infrequent and may arise in specific biological settings. To better understand the activity of the CTD phosphatases, we combined our structural analyses with data on CTD phosphatase expression in different human and mouse tissues. The results suggest that aspartate- and cysteine-based CTD-dephosphorylation acts in concert during cellular stress, when high levels of reactive oxygen species can inhibit the nucleophilic function of the catalytic cysteine, as occurs in mental and neurodegenerative disorders like schizophrenia, Alzheimer's and Parkinson's diseases. Moreover, these findings have significant implications for the study of the RNAPII-CTD dephosphorylation in eukaryotes.
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Affiliation(s)
- Tirso Pons
- Structural Biology and BioComputing Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
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26
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Myers BR, Sever N, Chong YC, Kim J, Belani JD, Rychnovsky S, Bazan JF, Beachy PA. Hedgehog pathway modulation by multiple lipid binding sites on the smoothened effector of signal response. Dev Cell 2013; 26:346-57. [PMID: 23954590 DOI: 10.1016/j.devcel.2013.07.015] [Citation(s) in RCA: 146] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 07/17/2013] [Accepted: 07/18/2013] [Indexed: 01/06/2023]
Abstract
Hedgehog (Hh) signaling during development and in postembryonic tissues requires activation of the 7TM oncoprotein Smoothened (Smo) by mechanisms that may involve endogenous lipidic modulators. Exogenous Smo ligands previously identified include the plant sterol cyclopamine (and its therapeutically useful synthetic mimics) and hydroxylated cholesterol derivatives (oxysterols); Smo is also highly sensitive to cellular sterol levels. The relationships between these effects are unclear because the relevant Smo structural determinants are unknown. We identify the conserved extracellular cysteine-rich domain (CRD) as the site of action for oxysterols on Smo, involving residues structurally analogous to those contacting the Wnt lipid adduct in the homologous Frizzled CRD; this modulatory effect is distinct from that of cyclopamine mimics, from Hh-mediated regulation, and from the permissive action of cellular sterol pools. These results imply that Hh pathway activity is sensitive to lipid binding at several Smo sites, suggesting mechanisms for tuning by multiple physiological inputs.
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Affiliation(s)
- Benjamin R Myers
- Department of Biochemistry, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
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Nedelcu D, Liu J, Xu Y, Jao C, Salic A. Oxysterol binding to the extracellular domain of Smoothened in Hedgehog signaling. Nat Chem Biol 2013; 9:557-64. [PMID: 23831757 PMCID: PMC3749252 DOI: 10.1038/nchembio.1290] [Citation(s) in RCA: 164] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 06/05/2013] [Indexed: 01/02/2023]
Abstract
Oxysterols bind the seven-transmembrane protein Smo (Smo) and potently activate vertebrate Hedgehog (Hh) signaling, a pathway essential in embryonic development, adult stem cell maintenance and cancer. It is unknown, however, whether oxysterols are important for normal vertebrate Hh signaling and whether antagonizing oxysterols can inhibit the Hh pathway. We developed azasterols that block Hh signaling by binding the oxysterol-binding site of Smo. We show that the binding site for oxysterols and azasterols maps to the extracellular, cysteine-rich domain of Smo and is completely separable from the site bound by other small-molecule modulators, located within the heptahelical bundle of Smo. Smo mutants in which oxysterol binding is abolished no longer respond to oxysterols and cannot be maximally activated by the Hh ligand. Our results show that oxysterol binding to vertebrate Smo is required for normal Hh signaling and that targeting the oxysterol-binding site is an effective strategy to inhibit Smo.
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Affiliation(s)
- Daniel Nedelcu
- 1] Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA. [2]
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28
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Abstract
PURPOSE OF REVIEW Wnt proteins are morphogens encoded by 19 mammalian genes that play essential roles in embryonic development, stem cell renewal, and adult tissue homeostasis. The recent publication of the first crystal structure of a Wnt protein represents a key step in the study of Wnt signaling. RECENT FINDINGS We discuss the basic aspects of Wnt signaling, provide historical background for why the proteins have been so challenging to study from a biochemical perspective, describe the lipid modifications that occur to Wnt proteins, and then discuss the implications of the recently reported crystal structure. SUMMARY The recent determination of the Wnt8-Fz8 structure has created new opportunities to better understand the mechanisms by which Wnt proteins activate downstream signaling pathways and has further clarified why lipid modification of Wnt is required for activation.
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Affiliation(s)
- Jiyuan Ke
- Laboratory of Structural Studies, Van Andel Research Institute, Grand Rapids, MI 49503, USA
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29
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Abstract
Polo-like kinases (PLKs) are marked by C-terminal polo box modules with critical protein interaction and subcellular targeting roles. Slevin et al. in this issue of Structure reveal the architecture of a hidden set of polo boxes from the divergent PLK4, a critical player in centrosome duplication, shedding new light on the evolution of PLKs and their functionally related kinase ZYG-1.
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30
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Abstract
The crystal structure of a Wnt morphogen bound to its Frizzled receptor ectodomain provides insights into the evolutionary provenance of this complex fold and offers an explanation for why Wnts utilize both lipid- and protein-mediated contacts to engage Frizzleds.
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Pei J, Grishin NV. Cysteine-rich domains related to Frizzled receptors and Hedgehog-interacting proteins. Protein Sci 2012; 21:1172-84. [PMID: 22693159 PMCID: PMC3537238 DOI: 10.1002/pro.2105] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 05/22/2012] [Accepted: 05/31/2012] [Indexed: 01/08/2023]
Abstract
Frizzled and Smoothened are homologous seven-transmembrane proteins functioning in the Wnt and Hedgehog signaling pathways, respectively. They harbor an extracellular cysteine-rich domain (FZ-CRD), a mobile evolutionary unit that has been found in a number of other metazoan proteins and Frizzled-like proteins in Dictyostelium. Domains distantly related to FZ-CRDs, in Hedgehog-interacting proteins (HHIPs), folate receptors and riboflavin-binding proteins (FRBPs), and Niemann-Pick Type C1 proteins (NPC1s), referred to as HFN-CRDs, exhibit similar structures and disulfide connectivity patterns compared with FZ-CRDs. We used computational analyses to expand the homologous set of FZ-CRDs and HFN-CRDs, providing a better understanding of their evolution and classification. First, FZ-CRD-containing proteins with various domain compositions were identified in several major eukaryotic lineages including plants and Chromalveolata, revealing a wider phylogenetic distribution of FZ-CRDs than previously recognized. Second, two new and distinct groups of highly divergent FZ-CRDs were found by sensitive similarity searches. One of them is present in the calcium channel component Mid1 in fungi and the uncharacterized FAM155 proteins in metazoans. Members of the other new FZ-CRD group occur in the metazoan-specific RECK (reversion-inducing-cysteine-rich protein with Kazal motifs) proteins that are putative tumor suppressors acting as inhibitors of matrix metalloproteases. Finally, sequence and three-dimensional structural comparisons helped us uncover a divergent HFN-CRD in glypicans, which are important morphogen-binding heparan sulfate proteoglycans. Such a finding reinforces the evolutionary ties between the Wnt and Hedgehog signaling pathways and underscores the importance of gene duplications in creating essential signaling components in metazoan evolution.
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Affiliation(s)
- Jimin Pei
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
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Janda CY, Waghray D, Levin AM, Thomas C, Garcia KC. Structural basis of Wnt recognition by Frizzled. Science 2012; 337:59-64. [PMID: 22653731 DOI: 10.1126/science.1222879] [Citation(s) in RCA: 612] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Wnts are lipid-modified morphogens that play critical roles in development principally through engagement of Frizzled receptors. The 3.25 angstrom structure of Xenopus Wnt8 (XWnt8) in complex with mouse Frizzled-8 (Fz8) cysteine-rich domain (CRD) reveals an unusual two-domain Wnt structure, not obviously related to known protein folds, resembling a "hand" with "thumb" and "index" fingers extended to grasp the Fz8-CRD at two distinct binding sites. One site is dominated by a palmitoleic acid lipid group projecting from serine 187 at the tip of Wnt's thumb into a deep groove in the Fz8-CRD. In the second binding site, the conserved tip of Wnt's "index finger" forms hydrophobic amino acid contacts with a depression on the opposite side of the Fz8-CRD. The conservation of amino acids in both interfaces appears to facilitate ligand-receptor cross-reactivity, which has important implications for understanding Wnt's functional pleiotropy and for developing Wnt-based drugs for cancer and regenerative medicine.
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Affiliation(s)
- Claudia Y Janda
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
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Role for B-cell adapter for PI3K (BCAP) as a signaling adapter linking Toll-like receptors (TLRs) to serine/threonine kinases PI3K/Akt. Proc Natl Acad Sci U S A 2011; 109:273-8. [PMID: 22187460 DOI: 10.1073/pnas.1118579109] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Toll like receptors (TLRs) use Toll-IL-1 receptor (TIR) domain-containing adapters, such as myeloid differentiation primary response gene 88 (MyD88) and TIR domain-containing adapter inducing IFN-β (TRIF), to induce activation of transcription factors, including NF-κB, MAP kinases, and IFN regulatory factors. TLR signaling also leads to activation of PI3K, but the molecular mechanism is not understood. Here we have discovered a unique role for B-cell adapter for PI3K (BCAP) in the TLR-signaling pathway. We find that BCAP has a functional N-terminal TIR homology domain and links TLR signaling to activation of PI3K. In addition, BCAP negatively regulates proinflammatory cytokine secretion upon TLR stimulation. In vivo, the absence of BCAP leads to exaggerated recruitment of inflammatory myeloid cells following infections and enhanced susceptibility to dextran sulfate sodium-induced colitis. Our results demonstrate that BCAP is a unique TIR domain-containing TLR signaling adapter crucial for linking TLRs to PI3K activation and regulating the inflammatory response.
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Malinauskas T, Aricescu AR, Lu W, Siebold C, Jones EY. Modular mechanism of Wnt signaling inhibition by Wnt inhibitory factor 1. Nat Struct Mol Biol 2011; 18:886-93. [PMID: 21743455 DOI: 10.1038/nsmb.2081] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 05/06/2011] [Indexed: 01/12/2023]
Abstract
Wnt morphogens control embryonic development and homeostasis in adult tissues. In vertebrates the N-terminal WIF domain (WIF-1(WD)) of Wnt inhibitory factor 1 (WIF-1) binds Wnt ligands. Our crystal structure of WIF-1(WD) reveals a previously unidentified binding site for phospholipid; two acyl chains extend deep into the domain, and the head group is exposed to the surface. Biophysical and cellular assays indicate that there is a WIF-1(WD) Wnt-binding surface proximal to the lipid head group but also implicate the five epidermal growth factor (EGF)-like domains (EGFs I-V) in Wnt binding. The six-domain WIF-1 crystal structure shows that EGFs I-V are wrapped back, interfacing with WIF-1(WD) at EGF III. EGFs II-V contain a heparan sulfate proteoglycan (HSPG)-binding site, consistent with conserved positively charged residues on EGF IV. This combination of HSPG- and Wnt-binding properties suggests a modular model for the localization of WIF-1 and for signal inhibition within morphogen gradients.
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Affiliation(s)
- Tomas Malinauskas
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
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Doubravska L, Krausova M, Gradl D, Vojtechova M, Tumova L, Lukas J, Valenta T, Pospichalova V, Fafilek B, Plachy J, Sebesta O, Korinek V. Fatty acid modification of Wnt1 and Wnt3a at serine is prerequisite for lipidation at cysteine and is essential for Wnt signalling. Cell Signal 2011; 23:837-48. [DOI: 10.1016/j.cellsig.2011.01.007] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 12/27/2010] [Accepted: 01/10/2011] [Indexed: 12/30/2022]
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Dorsal-ventral patterning: Crescent is a dorsally secreted Frizzled-related protein that competitively inhibits Tolloid proteases. Dev Biol 2011; 352:317-28. [PMID: 21295563 DOI: 10.1016/j.ydbio.2011.01.029] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Revised: 01/25/2011] [Accepted: 01/26/2011] [Indexed: 11/20/2022]
Abstract
In Xenopus, dorsal-ventral (D-V) patterning can self-regulate after embryo bisection. This is mediated by an extracellular network of proteins secreted by the dorsal and ventral centers of the gastrula. Different proteins of similar activity can be secreted at these two poles, but under opposite transcriptional control. Here we show that Crescent, a dorsal protein, can compensate for the loss of Sizzled, a ventral protein. Crescent is a secreted Frizzled-Related Protein (sFRP) known to regulate Wnt8 and Wnt11 activity. We now find that Crescent also regulates the BMP pathway. Crescent expression was increased by the BMP antagonist Chordin and repressed by BMP4, while the opposite was true for Sizzled. Crescent knock-down increased the expression of BMP target genes, and synergized with Sizzled morpholinos. Thus, Crescent loss-of-function is compensated by increased expression of its ventral counterpart Sizzled. Crescent overexpression dorsalized whole embryos but not ventral half-embryos, indicating that Crescent requires a dorsal component to exert its anti-BMP activity. Crescent protein lost its dorsalizing activity in Chordin-depleted embryos. When co-injected, Crescent and Chordin proteins greatly synergized in the dorsalization of Xenopus embryos. The molecular mechanism of these phenotypes is explained by the ability of Crescent to inhibit Tolloid metalloproteinases, which normally degrade Chordin. Enzyme kinetic studies showed that Crescent was a competitive inhibitor of Tolloid activity, which bound to Tolloid/BMP1 with a K(D) of 11 nM. In sum, Crescent is a new component of the D-V pathway, which functions as the dorsal counterpart of Sizzled, through the regulation of chordinases of the Tolloid family.
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Abstract
Little attention has been given to the impact of lipid metabolism on hair follicle biology and pathology. Three recent papers (one in the current issue) describe a major effect of altered lipid metabolism on hair growth. A direct link was made to at least one form of cicatricial alopecia, but the role lipids play in other follicular pathologies, such as the acneiform conditions, are inadequately explored and must be tested.
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Affiliation(s)
- Kurt S Stenn
- Aderans Research Institute, Inc., Philadelphia, Pennsylvania, USA.
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