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Geiser A, Foylan S, Tinning PW, Bryant NJ, Gould GW. GLUT4 dispersal at the plasma membrane of adipocytes: a super-resolved journey. Biosci Rep 2023; 43:BSR20230946. [PMID: 37791639 PMCID: PMC10600063 DOI: 10.1042/bsr20230946] [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: 09/07/2023] [Revised: 10/03/2023] [Accepted: 10/04/2023] [Indexed: 10/05/2023] Open
Abstract
In adipose tissue, insulin stimulates glucose uptake by mediating the translocation of GLUT4 from intracellular vesicles to the plasma membrane. In 2010, insulin was revealed to also have a fundamental impact on the spatial distribution of GLUT4 within the plasma membrane, with the existence of two GLUT4 populations at the plasma membrane being defined: (1) as stationary clusters and (2) as diffusible monomers. In this model, in the absence of insulin, plasma membrane-fused GLUT4 are found to behave as clusters. These clusters are thought to arise from exocytic events that retain GLUT4 at their fusion sites; this has been proposed to function as an intermediate hub between GLUT4 exocytosis and re-internalisation. By contrast, insulin stimulation induces the dispersal of GLUT4 clusters into monomers and favours a distinct type of GLUT4-vesicle fusion event, known as fusion-with-release exocytosis. Here, we review how super-resolution microscopy approaches have allowed investigation of the characteristics of plasma membrane-fused GLUT4 and further discuss regulatory step(s) involved in the GLUT4 dispersal machinery, introducing the scaffold protein EFR3 which facilitates localisation of phosphatidylinositol 4-kinase type IIIα (PI4KIIIα) to the cell surface. We consider how dispersal may be linked to the control of transporter activity, consider whether macro-organisation may be a widely used phenomenon to control proteins within the plasma membrane, and speculate on the origin of different forms of GLUT4-vesicle exocytosis.
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Affiliation(s)
- Angéline Geiser
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, U.K
| | - Shannan Foylan
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, U.K
| | - Peter W Tinning
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, U.K
| | - Nia J Bryant
- Department of Biology, University of York, Heslington, York, U.K
| | - Gwyn W Gould
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, U.K
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2
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Li Q, Huang L, Ding Y, Sherchan P, Peng W, Zhang JH. Recombinant Slit2 suppresses neuroinflammation and Cdc42-mediated brain infiltration of peripheral immune cells via Robo1-srGAP1 pathway in a rat model of germinal matrix hemorrhage. J Neuroinflammation 2023; 20:249. [PMID: 37899442 PMCID: PMC10613398 DOI: 10.1186/s12974-023-02935-2] [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: 03/22/2023] [Accepted: 10/17/2023] [Indexed: 10/31/2023] Open
Abstract
BACKGROUND Germinal matrix hemorrhage (GMH) is a devastating neonatal stroke, in which neuroinflammation is a critical pathological contributor. Slit2, a secreted extracellular matrix protein, plays a repulsive role in axon guidance and leukocyte chemotaxis via the roundabout1 (Robo1) receptor. This study aimed to explore effects of recombinant Slit2 on neuroinflammation and the underlying mechanism in a rat model of GMH. METHODS GMH was induced by stereotactically infusing 0.3 U of bacterial collagenase into the germinal matrix of 7-day-old Sprague Dawley rats. Recombinant Slit2 or its vehicle was administered intranasally at 1 h after GMH and daily for 3 consecutive days. A decoy receptor recombinant Robo1 was co-administered with recombinant Slit2 after GMH. Slit2 siRNA, srGAP1 siRNA or the scrambled sequences were administered intracerebroventricularly 24 h before GMH. Neurobehavior, brain water content, Western blotting, immunofluorescence staining and Cdc42 activity assays were performed. RESULTS The endogenous brain Slit2 and Robo1 expressions were increased after GMH. Robo1 was expressed on neuron, astrocytes and infiltrated peripheral immune cells in the brain. Endogenous Slit2 knockdown by Slit2 siRNA exacerbated brain edema and neurological deficits following GMH. Recombinant Slit2 (rSlit2) reduced neurological deficits, proinflammatory cytokines, intercellular adhesion molecules, peripheral immune cell markers, neuronal apoptosis and Cdc42 activity in the brain tissue after GMH. The anti-neuroinflammation effects were reversed by recombinant Robo1 co-administration or srGAP1 siRNA. CONCLUSIONS Recombinant Slit2 reduced neuroinflammation and neuron apoptosis after GMH. Its anti-neuroinflammation effects by suppressing onCdc42-mediated brain peripheral immune cells infiltration was at least in part via Robo1-srGAP1 pathway. These results imply that recombinant Slit2 may have potentials as a therapeutic option for neonatal brain injuries.
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Affiliation(s)
- Qian Li
- Department of Pediatrics, Army Medical Center, Army Medical University, 10 Changjiang Access Rd, Yuzhong District, Chongqing, 400042, China
- Women and Children's Hospital of Chongqing Medical University, 120 Longshan Access Rd, Yubei District, Chongqing, 400010, China
| | - Lei Huang
- Department of Physiology and Pharmacology, School of Medicine, Loma Linda University, 11041 Campus Street, Loma Linda, CA, 92354, USA
- Department of Neurosurgery, School of Medicine, Loma Linda University, 11234 Anderson Street, Loma Linda, CA, 92354, USA
| | - Yan Ding
- Department of Physiology and Pharmacology, School of Medicine, Loma Linda University, 11041 Campus Street, Loma Linda, CA, 92354, USA
| | - Prativa Sherchan
- Department of Physiology and Pharmacology, School of Medicine, Loma Linda University, 11041 Campus Street, Loma Linda, CA, 92354, USA
| | - Wenjie Peng
- Department of Pediatrics, Army Medical Center, Army Medical University, 10 Changjiang Access Rd, Yuzhong District, Chongqing, 400042, China
| | - John H Zhang
- Department of Physiology and Pharmacology, School of Medicine, Loma Linda University, 11041 Campus Street, Loma Linda, CA, 92354, USA.
- Department of Neurosurgery, School of Medicine, Loma Linda University, 11234 Anderson Street, Loma Linda, CA, 92354, USA.
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3
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Miyaguchi M, Nakanishi Y, Maturana AD, Mizutani K, Niimi T. Conformational Change of the Hairpin-like-structured Robo2 Ectodomain Allows NELL1/2 Binding. J Mol Biol 2022; 434:167777. [DOI: 10.1016/j.jmb.2022.167777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 07/29/2022] [Accepted: 08/02/2022] [Indexed: 10/16/2022]
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4
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Qu Z, Zhang A, Yan D. Robo functions as an attractive cue for glial migration through SYG-1/Neph. eLife 2020; 9:e57921. [PMID: 33211005 PMCID: PMC7676865 DOI: 10.7554/elife.57921] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 11/02/2020] [Indexed: 01/06/2023] Open
Abstract
As one of the most-studied receptors, Robo plays functions in many biological processes, and its functions highly depend on Slit, the ligand of Robo. Here we uncover a Slit-independent role of Robo in glial migration and show that neurons can release an extracellular fragment of Robo upon cleavage to attract glia during migration in Caenorhabditis elegans. Furthermore, we identified the conserved cell adhesion molecule SYG-1/Neph as a receptor for the cleaved extracellular Robo fragment to mediate glial migration and SYG-1/Neph functions through regulation of the WAVE complex. Our studies reveal a previously unknown Slit-independent function and regulatory mechanism of Robo and show that the cleaved extracellular fragment of Robo can function as a ligand for SYG-1/Neph to guide glial migration. As Robo, the cleaved region of Robo, and SYG-1/Neph are all highly conserved across the animal kingdom, our findings may present a conserved Slit-independent Robo mechanism during brain development.
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Affiliation(s)
- Zhongwei Qu
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
| | - Albert Zhang
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
| | - Dong Yan
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
- Department of Neurobiology, Regeneration Next Initiative, Duke Center for Neurodegeneration and Neurotherapeutics, and Duke Institute for Brain Sciences, Duke University Medical CenterDurhamUnited States
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5
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Brown HE, Evans TA. Minimal structural elements required for midline repulsive signaling and regulation of Drosophila Robo1. PLoS One 2020; 15:e0241150. [PMID: 33091076 PMCID: PMC7580999 DOI: 10.1371/journal.pone.0241150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 10/08/2020] [Indexed: 02/07/2023] Open
Abstract
The Roundabout (Robo) family of axon guidance receptors has a conserved ectodomain arrangement of five immunoglobulin-like (Ig) domains plus three fibronectin type III (Fn) repeats. Based on the strong evolutionary conservation of this domain structure among Robo receptors, as well as in vitro structural and domain-domain interaction studies of Robo family members, this ectodomain arrangement is predicted to be important for Robo receptor signaling in response to Slit ligands. Here, we define the minimal ectodomain structure required for Slit binding and midline repulsive signaling in vivo by Drosophila Robo1. We find that the majority of the Robo1 ectodomain is dispensable for both Slit binding and repulsive signaling. We show that a significant level of midline repulsive signaling activity is retained when all Robo1 ectodomain elements apart from Ig1 are deleted, and that the combination of Ig1 plus one additional ectodomain element (Ig2, Ig5, or Fn3) is sufficient to restore midline repulsion to wild type levels. Further, we find that deleting four out of five Robo1 Ig domains (ΔIg2-5) does not affect negative regulation of Robo1 by Commissureless (Comm) or Robo2, while variants lacking all three fibronectin repeats (ΔFn1-3 and ΔIg2-Fn3) are insensitive to regulation by both Comm and Robo2, signifying a novel regulatory role for Robo1's Fn repeats. Our results provide an in vivo perspective on the importance of the conserved 5+3 ectodomain structure of Robo receptors, and suggest that specific biochemical properties and/or ectodomain structural conformations observed in vitro for domains other than Ig1 may have limited significance for in vivo signaling in the context of midline repulsion.
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Affiliation(s)
- Haley E. Brown
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas, United States of America
| | - Timothy A. Evans
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas, United States of America
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6
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Peregrina C, Del Toro D. FLRTing Neurons in Cortical Migration During Cerebral Cortex Development. Front Cell Dev Biol 2020; 8:578506. [PMID: 33043013 PMCID: PMC7527468 DOI: 10.3389/fcell.2020.578506] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 08/17/2020] [Indexed: 01/26/2023] Open
Abstract
During development, two coordinated events shape the morphology of the mammalian cerebral cortex, leading to the cortex's columnar and layered structure: the proliferation of neuronal progenitors and cortical migration. Pyramidal neurons originating from germinal zones migrate along radial glial fibers to their final position in the cortical plate by both radial migration and tangential dispersion. These processes rely on the delicate balance of intercellular adhesive and repulsive signaling that takes place between neurons interacting with different substrates and guidance cues. Here, we focus on the function of the cell adhesion molecules fibronectin leucine-rich repeat transmembrane proteins (FLRTs) in regulating both the radial migration of neurons, as well as their tangential spread, and the impact these processes have on cortex morphogenesis. In combining structural and functional analysis, recent studies have begun to reveal how FLRT-mediated responses are precisely tuned - from forming different protein complexes to modulate either cell adhesion or repulsion in neurons. These approaches provide a deeper understanding of the context-dependent interactions of FLRTs with multiple receptors involved in axon guidance and synapse formation that contribute to finely regulated neuronal migration.
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Affiliation(s)
- Claudia Peregrina
- Department of Biological Sciences, Faculty of Medicine, Institute of Neurosciences, University of Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Daniel Del Toro
- Department of Biological Sciences, Faculty of Medicine, Institute of Neurosciences, University of Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
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7
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Pak JS, DeLoughery ZJ, Wang J, Acharya N, Park Y, Jaworski A, Özkan E. NELL2-Robo3 complex structure reveals mechanisms of receptor activation for axon guidance. Nat Commun 2020; 11:1489. [PMID: 32198364 PMCID: PMC7083938 DOI: 10.1038/s41467-020-15211-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Accepted: 02/24/2020] [Indexed: 11/24/2022] Open
Abstract
Axon pathfinding is critical for nervous system development, and it is orchestrated by molecular cues that activate receptors on the axonal growth cone. Robo family receptors bind Slit guidance cues to mediate axon repulsion. In mammals, the divergent family member Robo3 does not bind Slits, but instead signals axon repulsion from its own ligand, NELL2. Conversely, canonical Robos do not mediate NELL2 signaling. Here, we present the structures of NELL-Robo3 complexes, identifying a mode of ligand engagement for Robos that is orthogonal to Slit binding. We elucidate the structural basis for differential binding between NELL and Robo family members and show that NELL2 repulsive activity is a function of its Robo3 affinity and is enhanced by ligand trimerization. Our results reveal a mechanism of oligomerization-induced Robo activation for axon guidance and shed light on Robo family member ligand binding specificity, conformational variability, divergent modes of signaling, and evolution.
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Affiliation(s)
- Joseph S Pak
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
- Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, University of Chicago, Chicago, IL, 60637, USA
| | - Zachary J DeLoughery
- Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI, 02912, USA
- Robert J. and Nancy D. Carney Institute for Brain Science, Providence, RI, 02912, USA
| | - Jing Wang
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
- Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, University of Chicago, Chicago, IL, 60637, USA
| | - Nischal Acharya
- Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI, 02912, USA
- Robert J. and Nancy D. Carney Institute for Brain Science, Providence, RI, 02912, USA
| | - Yeonwoo Park
- Department of Human Genetics, University of Chicago, Chicago, IL, 60637, USA
| | - Alexander Jaworski
- Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI, 02912, USA.
- Robert J. and Nancy D. Carney Institute for Brain Science, Providence, RI, 02912, USA.
| | - Engin Özkan
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA.
- Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, University of Chicago, Chicago, IL, 60637, USA.
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8
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Niimi T. Roles of Slit Ligands and Their Roundabout (Robo) Family of Receptors in Bone Remodeling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 21:143-154. [PMID: 32986130 DOI: 10.1007/5584_2020_586] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Slit guidance ligands (Slits) and their roundabout (Robo) family of receptors are well-known axon guidance molecules that were originally identified in Drosophila mutants with commissural axon pathfinding defects. However, Slit-Robo signaling has been shown to be involved in not only neurogenesis, but also the development of other organs such as the kidney and heart. Recently, it was also revealed that Slit-Robo signaling plays an important role in bone metabolism. For example, osteoclast-derived Slit3 plays an osteoprotective role by synchronously stimulating bone formation by osteoblasts and suppressing bone resorption by osteoclasts through Robo receptors expressed on osteoblastic and osteoclastic cell lineages, making it a potential therapeutic target for metabolic bone disorders. Furthermore, osteoblast-derived Slit3 promotes bone formation indirectly as a proangiogenic factor. This review summarizes the recent progress on defining the roles of the Slit-Robo signaling in bone metabolism, and discusses the possible roles of the interaction between Robo and neural epidermal growth factor-like (NEL)-like (NELL) proteins that are novel ligands for Robo receptors.
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Affiliation(s)
- Tomoaki Niimi
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan.
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9
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Barak R, Yom-Tov G, Guez-Haddad J, Gasri-Plotnitsky L, Maimon R, Cohen-Berkman M, McCarthy AA, Perlson E, Henis-Korenblit S, Isupov MN, Opatowsky Y. Structural Principles in Robo Activation and Auto-inhibition. Cell 2019; 177:272-285.e16. [PMID: 30853216 DOI: 10.1016/j.cell.2019.02.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Revised: 12/06/2018] [Accepted: 02/06/2019] [Indexed: 01/28/2023]
Abstract
Proper brain function requires high-precision neuronal expansion and wiring, processes controlled by the transmembrane Roundabout (Robo) receptor family and their Slit ligands. Despite their great importance, the molecular mechanism by which Robos' switch from "off" to "on" states remains unclear. Here, we report a 3.6 Å crystal structure of the intact human Robo2 ectodomain (domains D1-8). We demonstrate that Robo cis dimerization via D4 is conserved through hRobo1, 2, and 3 and the C. elegans homolog SAX-3 and is essential for SAX-3 function in vivo. The structure reveals two levels of auto-inhibition that prevent premature activation: (1) cis blocking of the D4 dimerization interface and (2) trans interactions between opposing Robo receptors that fasten the D4-blocked conformation. Complementary experiments in mouse primary neurons and C. elegans support the auto-inhibition model. These results suggest that Slit stimulation primarily drives the release of Robo auto-inhibition required for dimerization and activation.
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Affiliation(s)
- Reut Barak
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Israel
| | - Galit Yom-Tov
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Israel
| | - Julia Guez-Haddad
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Israel
| | | | - Roy Maimon
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Israel
| | - Moran Cohen-Berkman
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Israel
| | | | - Eran Perlson
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Israel
| | | | | | - Yarden Opatowsky
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Israel.
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10
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Approaching the Roundabout: cis and trans Robo1 Contacts Revealed. Structure 2019; 26:183-184. [PMID: 29413320 DOI: 10.1016/j.str.2018.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In this issue of Structure,Aleksandrova et al. (2018) present low- and high-resolution structures of Robo1, a key player in axonal guidance. The structures shed light on the arrangement of Robo1 at the plasma membrane and provide evidence for back-to-back trans Robo1 contacts.
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11
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Yamamoto N, Kashiwagi M, Ishihara M, Kojima T, Maturana AD, Kuroda S, Niimi T. Robo2 contains a cryptic binding site for neural EGFL-like (NELL) protein 1/2. J Biol Chem 2019; 294:4693-4703. [PMID: 30700556 DOI: 10.1074/jbc.ra118.005819] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 01/14/2019] [Indexed: 12/15/2022] Open
Abstract
The signaling pathways that are mediated by Slit ligands and their Roundabout (Robo) family of receptors play multifunctional roles in the development of the nervous system and other organs. A recent study identified neural epidermal growth factor-like (NEL)-like 2 (NELL2) as a novel ligand for Robo3. In this study, we carried out a comprehensive analysis of the interaction between NELL1 and the Robo family of receptors and demonstrated that Robo2 contains a cryptic binding site for both NELL1 and NELL2. NELL1/2 binds to the first fibronectin type III (FNIII) domain of Robo2 but not to intact Robo2. Mutation analysis revealed that several amino acids within the first FNIII domain are critical for NELL1 binding to Robo2 but not to Robo1. The Robo2 deletion mutants without the fourth immunoglobulin domain and single amino acid substitution mutants that can influence the architecture of the ectodomain facilitated binding to NELL1/2. Acidic conditions increased the binding affinity of Robo2 for NELL1. These results suggest that Robo2 functions as a receptor for NELL1/2, particularly under circumstances where Robo2 undergoes proteolytic digestion. If this is not the case, conformational changes of the ectodomain of Robo2 may unmask the binding site for NELL1/2.
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Affiliation(s)
- Naoka Yamamoto
- From the Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan and
| | - Manabu Kashiwagi
- From the Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan and
| | - Manami Ishihara
- From the Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan and
| | - Takaaki Kojima
- From the Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan and
| | - Andrés D Maturana
- From the Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan and
| | - Shun'ichi Kuroda
- the Institute of Scientific and Industrial Research, Osaka University, Osaka 567-0047, Japan
| | - Tomoaki Niimi
- From the Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan and
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12
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Abstract
The creation of complex neuronal networks relies on ligand-receptor interactions that mediate attraction or repulsion towards specific targets. Roundabouts comprise a family of single-pass transmembrane receptors facilitating this process upon interaction with the soluble extracellular ligand Slit protein family emanating from the midline. Due to the complexity and flexible nature of Robo receptors , their overall structure has remained elusive until now. Recent structural studies of the Robo 1 and Robo 2 ectodomains have provided the basis for a better understanding of their signalling mechanism. These structures reveal how Robo receptors adopt an auto-inhibited conformation on the cell surface that can be further stabilised by cis and/or trans oligmerisation arrays. Upon Slit -N binding Robo receptors must undergo a conformational change for Ig4 mediated dimerisation and signaling, probably via endocytosis. Furthermore, it's become clear that Robo receptors do not only act alone, but as large and more complex cell surface receptor assemblies to manifest directional and growth effects in a concerted fashion. These context dependent assemblies provide a mechanism to fine tune attractive and repulsive signals in a combinatorial manner required during neuronal development. While a mechanistic understanding of Slit mediated Robo signaling has advanced significantly further structural studies on larger assemblies are required for the design of new experiments to elucidate their role in cell surface receptor complexes. These will be necessary to understand the role of Slit -Robo signaling in neurogenesis, angiogenesis, organ development and cancer progression. In this chapter, we provide a review of the current knowledge in the field with a particular focus on the Roundabout receptor family.
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Affiliation(s)
- Francesco Bisiak
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue Des Martyrs, 38042, Grenoble, France.
| | - Andrew A McCarthy
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue Des Martyrs, 38042, Grenoble, France.
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13
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Pilling D, Chinea LE, Consalvo KM, Gomer RH. Different Isoforms of the Neuronal Guidance Molecule Slit2 Directly Cause Chemoattraction or Chemorepulsion of Human Neutrophils. THE JOURNAL OF IMMUNOLOGY 2018; 202:239-248. [PMID: 30510066 DOI: 10.4049/jimmunol.1800681] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 11/02/2018] [Indexed: 12/11/2022]
Abstract
The movement of neutrophils between blood and tissues appears to be regulated by chemoattractants and chemorepellents. Compared with neutrophil chemoattractants, relatively little is known about neutrophil chemorepellents. Slit proteins are endogenously cleaved into a variety of N- and C-terminal fragments, and these fragments are neuronal chemorepellents and inhibit chemoattraction of many cell types, including neutrophils. In this report, we show that the ∼140-kDa N-terminal Slit2 fragment (Slit2-N) is a chemoattractant and the ∼110-kDa N-terminal Slit2 fragment (Slit2-S) is a chemorepellent for human neutrophils. The effects of both Slit2 fragments were blocked by Abs to the Slit2 receptor Roundabout homolog 1 or the Slit2 coreceptor Syndecan-4. Slit2-N did not appear to activate Ras but increased phosphatidylinositol 3,4,5-triphosphate levels. Slit2-N-induced chemoattraction was unaffected by Ras inhibitors, reversed by PI3K inhibitors, and blocked by Cdc42 and Rac inhibitors. In contrast, Slit2-S activated Ras but did not increase phosphatidylinositol 3,4,5-triphosphate levels. Slit2-S-induced chemorepulsion was blocked by Ras and Rac inhibitors, not affected by PI3K inhibitors, and reversed by Cdc42 inhibitors. Slit2-N, but not Slit2-S, increased neutrophil adhesion, myosin L chain 2 phosphorylation, and polarized actin formation and single pseudopods at the leading edge of cells. Slit2-S induced multiple pseudopods. These data suggest that Slit2 isoforms use similar receptors but different intracellular signaling pathways and have different effects on the cytoskeleton and pseudopods to induce neutrophil chemoattraction or chemorepulsion.
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Affiliation(s)
- Darrell Pilling
- Department of Biology, Texas A&M University, College Station, TX 77843-3474
| | - Luis E Chinea
- Department of Biology, Texas A&M University, College Station, TX 77843-3474
| | - Kristen M Consalvo
- Department of Biology, Texas A&M University, College Station, TX 77843-3474
| | - Richard H Gomer
- Department of Biology, Texas A&M University, College Station, TX 77843-3474
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14
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Marsango S, Ward RJ, Alvarez-Curto E, Milligan G. Muscarinic receptor oligomerization. Neuropharmacology 2018; 136:401-410. [PMID: 29146505 PMCID: PMC6078712 DOI: 10.1016/j.neuropharm.2017.11.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 11/01/2017] [Accepted: 11/13/2017] [Indexed: 12/30/2022]
Abstract
G protein-coupled receptors (GPCRs) have been classically described as monomeric entities that function by binding in a 1:1 stoichiometric ratio to both ligand and downstream signalling proteins. However, in recent years, a growing number of studies has supported the hypothesis that these receptors can interact to form dimers and higher order oligomers although the molecular basis for these interactions, the overall quaternary arrangements and the functional importance of GPCR oligomerization remain topics of intense speculation. Muscarinic acetylcholine receptors belong to class A of the GPCR family. Each muscarinic receptor subtype has its own particular distribution throughout the central and peripheral nervous systems. In the central nervous system, muscarinic receptors regulate several sensory, cognitive, and motor functions while, in the peripheral nervous system, they are involved in the regulation of heart rate, stimulation of glandular secretion and smooth muscle contraction. Muscarinic acetylcholine receptors have long been used as a model for the study of GPCR structure and function and to address aspects of GPCR dimerization using a broad range of approaches. In this review, the prevailing knowledge regarding the quaternary arrangement for the various muscarinic acetylcholine receptors has been summarized by discussing work ranging from initial results obtained using more traditional biochemical approaches to those generated with more modern biophysical techniques. This article is part of the Special Issue entitled 'Neuropharmacology on Muscarinic Receptors'.
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Affiliation(s)
- Sara Marsango
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
| | - Richard J Ward
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
| | - Elisa Alvarez-Curto
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - Graeme Milligan
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
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15
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Aleksandrova N, Gutsche I, Kandiah E, Avilov SV, Petoukhov MV, Seiradake E, McCarthy AA. Robo1 Forms a Compact Dimer-of-Dimers Assembly. Structure 2018; 26:320-328.e4. [PMID: 29307485 PMCID: PMC5807052 DOI: 10.1016/j.str.2017.12.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 09/28/2017] [Accepted: 12/04/2017] [Indexed: 01/27/2023]
Abstract
Roundabout (Robo) receptors provide an essential repulsive cue in neuronal development following Slit ligand binding. This important signaling pathway can also be hijacked in numerous cancers, making Slit-Robo an attractive therapeutic target. However, little is known about how Slit binding mediates Robo activation. Here we present the crystal structure of Robo1 Ig1-4 and Robo1 Ig5, together with a negative stain electron microscopy reconstruction of the Robo1 ectodomain. These results show how the Robo1 ectodomain is arranged as compact dimers, mainly mediated by the central Ig domains, which can further interact in a "back-to-back" fashion to generate a tetrameric assembly. We also observed no change in Robo1 oligomerization upon interaction with the dimeric Slit2-N ligand using fluorescent imaging. Taken together with previous studies we propose that Slit2-N binding results in a conformational change of Robo1 to trigger cell signaling.
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Affiliation(s)
- Nataliia Aleksandrova
- European Molecular Biology Laboratory, Grenoble Outstation, 71 avenue des Martyrs, 38042 Grenoble, France
| | - Irina Gutsche
- University Grenoble Alpes, CNRS, CEA, IBS, 71 avenue des Martyrs, 38044 Grenoble, France
| | - Eaazhisai Kandiah
- University Grenoble Alpes, CNRS, CEA, IBS, 71 avenue des Martyrs, 38044 Grenoble, France
| | - Sergiy V Avilov
- European Molecular Biology Laboratory, Grenoble Outstation, 71 avenue des Martyrs, 38042 Grenoble, France
| | - Maxim V Petoukhov
- European Molecular Biology Laboratory, Hamburg Unit, Notkestrasse 85, Hamburg 22607, Germany; Federal Scientific Research Centre "Crystallography and Photonics" of Russian Academy of Sciences, Leninsky Prospect 59, 119333 Moscow, Russian Federation; A. N. Frumkin Institute of Physical Chemistry and Electrochemistry RAS, Leninsky Prospect 31, 119071 Moscow, Russian Federation; N.N. Semenov Institute of Chemical Physics of Russian Academy of Sciences, Kosygina Street 4, 119991 Moscow, Russian Federation
| | - Elena Seiradake
- Department of Biochemistry, University of Oxford, South Parks Road, OX1 3QU Oxford, UK
| | - Andrew A McCarthy
- European Molecular Biology Laboratory, Grenoble Outstation, 71 avenue des Martyrs, 38042 Grenoble, France.
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16
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Dunsing V, Mayer M, Liebsch F, Multhaup G, Chiantia S. Direct evidence of amyloid precursor-like protein 1 trans interactions in cell-cell adhesion platforms investigated via fluorescence fluctuation spectroscopy. Mol Biol Cell 2017; 28:3609-3620. [PMID: 29021345 PMCID: PMC5706989 DOI: 10.1091/mbc.e17-07-0459] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/13/2017] [Accepted: 10/04/2017] [Indexed: 01/25/2023] Open
Abstract
The amyloid precursor–like protein 1 (APLP1) plays a role in synaptic adhesion and synaptogenesis. In this work, we use quantitative fluorescence microscopy to demonstrate the existence of APLP1–APLP1 trans interaction across cell–cell junctions and propose a model explaining the molecular mechanism driving APLP1 multimerization. The amyloid precursor–like protein 1 (APLP1) is a type I transmembrane protein that plays a role in synaptic adhesion and synaptogenesis. Past investigations indicated that APLP1 is involved in the formation of protein–protein complexes that bridge the junctions between neighboring cells. Nevertheless, APLP1–APLP1 trans interactions have never been directly observed in higher eukaryotic cells. Here, we investigated APLP1 interactions and dynamics directly in living human embryonic kidney cells using fluorescence fluctuation spectroscopy techniques, namely cross-correlation scanning fluorescence correlation spectroscopy and number and brightness analysis. Our results show that APLP1 forms homotypic trans complexes at cell–cell contacts. In the presence of zinc ions, the protein forms macroscopic clusters, exhibiting an even higher degree of trans binding and strongly reduced dynamics. Further evidence from giant plasma membrane vesicles suggests that the presence of an intact cortical cytoskeleton is required for zinc-induced cis multimerization. Subsequently, large adhesion platforms bridging interacting cells are formed through APLP1–APLP1 trans interactions. Taken together, our results provide direct evidence that APLP1 functions as a neuronal zinc-dependent adhesion protein and allow a more detailed understanding of the molecular mechanisms driving the formation of APLP1 adhesion platforms.
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Affiliation(s)
- Valentin Dunsing
- Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany
| | - Magnus Mayer
- Institute of Chemistry and Biochemistry, Free University of Berlin, 14195 Berlin, Germany
| | - Filip Liebsch
- Department of Pharmacology and Therapeutics/Integrated Program in Neuroscience, McGill University, Montreal, QC H3G 1Y63, Canada
| | - Gerhard Multhaup
- Department of Pharmacology and Therapeutics/Integrated Program in Neuroscience, McGill University, Montreal, QC H3G 1Y63, Canada
| | - Salvatore Chiantia
- Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany
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17
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Pediani JD, Ward RJ, Marsango S, Milligan G. Spatial Intensity Distribution Analysis: Studies of G Protein-Coupled Receptor Oligomerisation. Trends Pharmacol Sci 2017; 39:175-186. [PMID: 29032835 PMCID: PMC5783713 DOI: 10.1016/j.tips.2017.09.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/04/2017] [Accepted: 09/14/2017] [Indexed: 02/08/2023]
Abstract
Spatial intensity distribution analysis (SpIDA) is a recently developed approach for determining quaternary structure information on fluorophore-labelled proteins of interest in situ. It can be applied to live or fixed cells and native tissue. Using confocal images, SpIDA generates fluorescence intensity histograms that are analysed by super-Poissonian distribution functions to obtain density and quantal brightness values of the fluorophore-labelled protein of interest. This allows both expression level and oligomerisation state of the protein to be determined. We describe the application of SpIDA to investigate the oligomeric state of G protein-coupled receptors (GPCRs) at steady state and following cellular challenge, and consider how SpIDA may be used to explore GPCR quaternary organisation in pathophysiology and to stratify medicines. GPCRs may exist and function as monomers: however, abundant evidence suggests they can form dimers/oligomers. This concept has implications for drug discovery as it may offer opportunities to modulate the effects of known pharmaceuticals or identify new drug therapies. A variety of approaches have been applied to this issue from traditional biochemical techniques, via resonance energy transfer approaches to recently developed image analysis-based techniques such as SpIDA. This uses mathematical analysis of confocal microscopy images to generate quantal brightness and density information for a fluorophore-tagged receptor. SpIDA can be applied to live or fixed cells and native tissue. SpIDA has been applied to GPCRs from each of the major subfamilies to explore their oligomerisation status at steady state and their regulation by receptor density and ligand binding.
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Affiliation(s)
- John D Pediani
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Richard J Ward
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Sara Marsango
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Graeme Milligan
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
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18
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Yom-Tov G, Barak R, Matalon O, Barda-Saad M, Guez-Haddad J, Opatowsky Y. Robo Ig4 Is a Dimerization Domain. J Mol Biol 2017; 429:3606-3616. [PMID: 29017837 DOI: 10.1016/j.jmb.2017.10.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 10/02/2017] [Accepted: 10/02/2017] [Indexed: 01/06/2023]
Abstract
Robo receptors play pivotal roles in axonal guidance as well as in neurogenesis, angiogenesis, cell migration, and cancer progression and invasiveness. They are considered to be attractive drug targets for the treatment of cancer, ocular neovascular disorders, chronic kidney diseases, and more. Despite their great importance, the mechanisms by which Robo receptors switch from their "off" to "on" states remain obscure. One possibility involves a monomer-to-dimer or dimer-to-monomer transition that facilitates the recruitment and activation of enzymatic effectors to instigate intracellular signaling. However, it is not known which domains mediate Robo dimerization, or the structural properties of the dimeric interactions. Here, we identify the extracellular Ig4 (D4) as a Robo dimerization domain. We have determined the crystal structure of the tandem Ig4-5 domains (D4-5) of human Robo2 and found that a hydrophobic surface on D4 mediates close homotypic contacts with a reciprocal D4. Analytical ultracentrifugation measurements of intact and mutated D4-5 shows that dimerization through the D4 interface is specific and has a dimerization dissociation constant of 16.9μM in solution. Direct fluorescence resonance energy transfer dimerization measurements in HEK293 cells corroborate the dimerization of transmembrane hRobo2 through D4, and a functional COS-7 cell collapse assay links D4-mediated dimerization with Robo intracellular signaling. The high level of conservation in the D4 dimerization interface throughout all Robo orthologs and paralogs implies that D4-mediated dimerization is a central hallmark in Robo activation and signaling.
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Affiliation(s)
- Galit Yom-Tov
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Reut Barak
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Omri Matalon
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Mira Barda-Saad
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Julia Guez-Haddad
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Yarden Opatowsky
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel.
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19
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Jonas KC, Hanyaloglu AC. Impact of G protein-coupled receptor heteromers in endocrine systems. Mol Cell Endocrinol 2017; 449:21-27. [PMID: 28115188 DOI: 10.1016/j.mce.2017.01.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 01/05/2017] [Accepted: 01/19/2017] [Indexed: 12/26/2022]
Abstract
The fine-tuning of endocrine homeostasis is regulated by dynamic receptor mediated processes. The superfamily of G protein-coupled receptors (GPCRs) have diverse roles in the modulation of all endocrine axes, thus understanding the mechanisms underpinning their functionality is paramount for treatment of endocrinopathies. Evidence over the last 20 years has highlighted homo and heteromerization as a key mode of mediating GPCR functional diversity. This review will discuss the concept of GPCR heteromerization and its relevance to endocrine function, detailing in vitro and in vivo evidence, and exploring current and potential pharmacological strategies for specific targeting of GPCR heteromers in endocrine heath and disease.
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Affiliation(s)
- K C Jonas
- Cell Biology and Genetics Research Centre, Centre for Medical and Biomedical Education, St George's, University of London, UK.
| | - A C Hanyaloglu
- Institute of Reproductive and Developmental Biology, Dept. Surgery and Cancer, Imperial College London, UK
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20
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Spatial intensity distribution analysis quantifies the extent and regulation of homodimerization of the secretin receptor. Biochem J 2017; 474:1879-1895. [PMID: 28424368 PMCID: PMC5442643 DOI: 10.1042/bcj20170184] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 04/18/2017] [Accepted: 04/19/2017] [Indexed: 01/02/2023]
Abstract
Previous studies have indicated that the G-protein-coupled secretin receptor is present as a homodimer, organized through symmetrical contacts in transmembrane domain IV, and that receptor dimerization is critical for high-potency signalling by secretin. However, whether all of the receptor exists in the dimeric form or if this is regulated is unclear. We used measures of quantal brightness of the secretin receptor tagged with monomeric enhanced green fluorescent protein (mEGFP) and spatial intensity distribution analysis to assess this. Calibration using cells expressing plasma membrane-anchored forms of mEGFP initially allowed us to demonstrate that the epidermal growth factor receptor is predominantly monomeric in the absence of ligand and while wild-type receptor was rapidly converted into a dimeric form by ligand, a mutated form of this receptor remained monomeric. Equivalent studies showed that, at moderate expression levels, the secretin receptor exists as a mixture of monomeric and dimeric forms, with little evidence of higher-order complexity. However, sodium butyrate-induced up-regulation of the receptor resulted in a shift from monomeric towards oligomeric organization. In contrast, a form of the secretin receptor containing a pair of mutations on the lipid-facing side of transmembrane domain IV was almost entirely monomeric. Down-regulation of the secretin receptor-interacting G-protein Gαs did not alter receptor organization, indicating that dimerization is defined specifically by direct protein–protein interactions between copies of the receptor polypeptide, while short-term treatment with secretin had no effect on organization of the wild-type receptor but increased the dimeric proportion of the mutated receptor variant.
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21
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Friocourt F, Chédotal A. The Robo3 receptor, a key player in the development, evolution, and function of commissural systems. Dev Neurobiol 2017; 77:876-890. [DOI: 10.1002/dneu.22478] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 12/04/2016] [Accepted: 12/06/2016] [Indexed: 12/15/2022]
Affiliation(s)
- François Friocourt
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision; 17 Rue Moreau Paris 75012 France
| | - Alain Chédotal
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision; 17 Rue Moreau Paris 75012 France
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22
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Abstract
Axon guidance relies on a combinatorial code of receptor and ligand interactions that direct adhesive/attractive and repulsive cellular responses. Recent structural data have revealed many of the molecular mechanisms that govern these interactions and enabled the design of sophisticated mutant tools to dissect their biological functions. Here, we discuss the structure/function relationships of four major classes of guidance cues (ephrins, semaphorins, slits, netrins) and examples of morphogens (Wnt, Shh) and of cell adhesion molecules (FLRT). These cell signaling systems rely on specific modes of receptor-ligand binding that are determined by selective binding sites; however, defined structure-encoded receptor promiscuity also enables cross talk between different receptor/ligand families and can also involve extracellular matrix components. A picture emerges in which a multitude of highly context-dependent structural assemblies determines the finely tuned cellular behavior required for nervous system development.
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Affiliation(s)
- Elena Seiradake
- Department of Biochemistry, Oxford University, Oxford OX1 3QU, United Kingdom;
| | - E Yvonne Jones
- Wellcome Trust Centre for Human Genetics, Oxford University, Oxford OX3 7BN, United Kingdom;
| | - Rüdiger Klein
- Max Planck Institute of Neurobiology, 82152 Munich-Martinsried, Germany;
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
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23
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Godin AG, Rappaz B, Potvin-Trottier L, Kennedy TE, De Koninck Y, Wiseman PW. Spatial Intensity Distribution Analysis Reveals Abnormal Oligomerization of Proteins in Single Cells. Biophys J 2016; 109:710-21. [PMID: 26287623 DOI: 10.1016/j.bpj.2015.06.068] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 06/09/2015] [Accepted: 06/22/2015] [Indexed: 12/30/2022] Open
Abstract
Knowledge of membrane receptor organization is essential for understanding the initial steps in cell signaling and trafficking mechanisms, but quantitative analysis of receptor interactions at the single-cell level and in different cellular compartments has remained highly challenging. To achieve this, we apply a quantitative image analysis technique-spatial intensity distribution analysis (SpIDA)-that can measure fluorescent particle concentrations and oligomerization states within different subcellular compartments in live cells. An important technical challenge faced by fluorescence microscopy-based measurement of oligomerization is the fidelity of receptor labeling. In practice, imperfect labeling biases the distribution of oligomeric states measured within an aggregated system. We extend SpIDA to enable analysis of high-order oligomers from fluorescence microscopy images, by including a probability weighted correction algorithm for nonemitting labels. We demonstrated that this fraction of nonemitting probes could be estimated in single cells using SpIDA measurements on model systems with known oligomerization state. Previously, this artifact was measured using single-step photobleaching. This approach was validated using computer-simulated data and the imperfect labeling was quantified in cells with ion channels of known oligomer subunit count. It was then applied to quantify the oligomerization states in different cell compartments of the proteolipid protein (PLP) expressed in COS-7 cells. Expression of a mutant PLP linked to impaired trafficking resulted in the detection of PLP tetramers that persist in the endoplasmic reticulum, while no difference was measured at the membrane between the distributions of wild-type and mutated PLPs. Our results demonstrate that SpIDA allows measurement of protein oligomerization in different compartments of intact cells, even when fractional mislabeling occurs as well as photobleaching during the imaging process, and reveals insights into the mechanism underlying impaired trafficking of PLP.
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Affiliation(s)
- Antoine G Godin
- Department of Physics, McGill University, Montréal, Québec, Canada; Institut Universitaire en Santé Mentale de Québec, Québec, Canada
| | - Benjamin Rappaz
- Department of Physics, McGill University, Montréal, Québec, Canada; Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, Québec, Canada; Program in NeuroEngineering, McGill University, Montréal, Québec, Canada
| | | | - Timothy E Kennedy
- Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, Québec, Canada; Program in NeuroEngineering, McGill University, Montréal, Québec, Canada
| | - Yves De Koninck
- Institut Universitaire en Santé Mentale de Québec, Québec, Canada; Département de Psychiatrie et Neurosciences, Université Laval, Québec, Canada; Department of Pharmacology & Therapeutics, McGill University, Montréal, Québec, Canada; Alan Edwards Center for Research of Pain, McGill University, Montréal, Québec, Canada
| | - Paul W Wiseman
- Department of Physics, McGill University, Montréal, Québec, Canada; Program in NeuroEngineering, McGill University, Montréal, Québec, Canada; Department of Chemistry, McGill University, Montréal, Québec, Canada.
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24
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Pediani JD, Ward RJ, Godin AG, Marsango S, Milligan G. Dynamic Regulation of Quaternary Organization of the M1 Muscarinic Receptor by Subtype-selective Antagonist Drugs. J Biol Chem 2016; 291:13132-46. [PMID: 27080256 PMCID: PMC4933229 DOI: 10.1074/jbc.m115.712562] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Indexed: 12/14/2022] Open
Abstract
Although rhodopsin-like G protein-coupled receptors can exist as both monomers and non-covalently associated dimers/oligomers, the steady-state proportion of each form and whether this is regulated by receptor ligands are unknown. Herein we address these topics for the M1 muscarinic acetylcholine receptor, a key molecular target for novel cognition enhancers, by using spatial intensity distribution analysis. This method can measure fluorescent particle concentration and assess oligomerization states of proteins within defined regions of living cells. Imaging and analysis of the basolateral surface of cells expressing some 50 molecules·μm−2 human muscarinic M1 receptor identified a ∼75:25 mixture of receptor monomers and dimers/oligomers. Both sustained and shorter term treatment with the selective M1 antagonist pirenzepine resulted in a large shift in the distribution of receptor species to favor the dimeric/oligomeric state. Although sustained treatment with pirenzepine also resulted in marked up-regulation of the receptor, simple mass action effects were not the basis for ligand-induced stabilization of receptor dimers/oligomers. The related antagonist telenzepine also produced stabilization and enrichment of the M1 receptor dimer population, but the receptor subtype non-selective antagonists atropine and N-methylscopolamine did not. In contrast, neither pirenzepine nor telenzepine altered the quaternary organization of the related M3 muscarinic receptor. These data provide unique insights into the selective capacity of receptor ligands to promote and/or stabilize receptor dimers/oligomers and demonstrate that the dynamics of ligand regulation of the quaternary organization of G protein-coupled receptors is markedly more complex than previously appreciated. This may have major implications for receptor function and behavior.
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Affiliation(s)
- John D Pediani
- From the Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom and
| | - Richard J Ward
- From the Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom and
| | - Antoine G Godin
- Institut d'Optique and CNRS, Laboratoire Photonique, Numérique et Nanosciences (LP2N) and Université de Bordeaux, LP2N, F-33405, UMR 5298, 33405 Talence Cedex, France
| | - Sara Marsango
- From the Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom and
| | - Graeme Milligan
- From the Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom and
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25
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Ward RJ, Pediani JD, Godin AG, Milligan G. Regulation of oligomeric organization of the serotonin 5-hydroxytryptamine 2C (5-HT2C) receptor observed by spatial intensity distribution analysis. J Biol Chem 2015; 290:12844-57. [PMID: 25825490 PMCID: PMC4432300 DOI: 10.1074/jbc.m115.644724] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Indexed: 12/19/2022] Open
Abstract
The questions of whether G protein-coupled receptors exist as monomers, dimers, and/or oligomers and if these species interconvert in a ligand-dependent manner are among the most contentious current issues in biology. When employing spatial intensity distribution analysis to laser scanning confocal microscope images of cells stably expressing either a plasma membrane-associated form of monomeric enhanced green fluorescent protein (eGFP) or a tandem version of this fluorophore, the eGFP tandem was identified as a dimer. Similar studies on cells stably expressing an eGFP-tagged form of the epidermal growth factor receptor demonstrated that, although largely a monomer in the basal state, this receptor rapidly became predominantly dimeric upon the addition of its ligand epidermal growth factor. In cells induced to express an eGFP-tagged form of the serotonin 5-hydroxytryptamine 2C (5-HT2C) receptor, global analysis of construct quantal brightness was consistent with the predominant form of the receptor being dimeric. However, detailed spatial intensity distribution analysis demonstrated the presence of multiple forms ranging from monomers to higher-order oligomers. Furthermore, treatment with chemically distinct 5-HT2C receptor antagonists resulted in a time-dependent change in the quaternary organization to one in which there was a preponderance of receptor monomers. This antagonist-mediated effect was reversible, because washout of the ligand resulted in the regeneration of many of the oligomeric forms of the receptor.
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Affiliation(s)
- Richard J Ward
- From the Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - John D Pediani
- From the Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Antoine G Godin
- the University of Bordeaux, LP2N, UMR 5298, F-33405 Talence, France, and the Institut d'Optique Graduate School and CNRS, LP2N, UMR 5298, F-33405 Talence, France
| | - Graeme Milligan
- From the Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom,
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