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Cadosch N, Gil-Cruz C, Perez-Shibayama C, Ludewig B. Cardiac Fibroblastic Niches in Homeostasis and Inflammation. Circ Res 2024; 134:1703-1717. [PMID: 38843287 PMCID: PMC11149942 DOI: 10.1161/circresaha.124.323892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Revised: 04/12/2024] [Accepted: 04/18/2024] [Indexed: 06/09/2024]
Abstract
Fibroblasts are essential for building and maintaining the structural integrity of all organs. Moreover, fibroblasts can acquire an inflammatory phenotype to accommodate immune cells in specific niches and to provide migration, differentiation, and growth factors. In the heart, balancing of fibroblast activity is critical for cardiac homeostasis and optimal organ function during inflammation. Fibroblasts sustain cardiac homeostasis by generating local niche environments that support housekeeping functions and by actively engaging in intercellular cross talk. During inflammatory perturbations, cardiac fibroblasts rapidly switch to an inflammatory state and actively communicate with infiltrating immune cells to orchestrate immune cell migration and activity. Here, we summarize the current knowledge on the molecular landscape of cardiac fibroblasts, focusing on their dual role in promoting tissue homeostasis and modulating immune cell-cardiomyocyte interaction. In addition, we discuss potential future avenues for manipulating cardiac fibroblast activity during myocardial inflammation.
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Affiliation(s)
- Nadine Cadosch
- Institute of Immunobiology, Medical Research Center, Kantonsspital St. Gallen, St. Gallen, Switzerland (N.C., C.G.-C., C.P.-S., B.L.)
| | - Cristina Gil-Cruz
- Institute of Immunobiology, Medical Research Center, Kantonsspital St. Gallen, St. Gallen, Switzerland (N.C., C.G.-C., C.P.-S., B.L.)
- University Heart Center, University Hospital Zurich and University of Zurich, Zurich, Switzerland (C.G.-C., B.L.), University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Christian Perez-Shibayama
- Institute of Immunobiology, Medical Research Center, Kantonsspital St. Gallen, St. Gallen, Switzerland (N.C., C.G.-C., C.P.-S., B.L.)
| | - Burkhard Ludewig
- Institute of Immunobiology, Medical Research Center, Kantonsspital St. Gallen, St. Gallen, Switzerland (N.C., C.G.-C., C.P.-S., B.L.)
- University Heart Center, University Hospital Zurich and University of Zurich, Zurich, Switzerland (C.G.-C., B.L.), University Hospital Zurich and University of Zurich, Zurich, Switzerland
- Center for Translational and Experimental Cardiology (B.L.), University Hospital Zurich and University of Zurich, Zurich, Switzerland
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2
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Lysko DE, Talbot WS. Unmyelinated sensory neurons use Neuregulin signals to promote myelination of interneurons in the CNS. Cell Rep 2022; 41:111669. [PMID: 36384112 PMCID: PMC9719401 DOI: 10.1016/j.celrep.2022.111669] [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: 04/01/2022] [Revised: 09/06/2022] [Accepted: 10/25/2022] [Indexed: 11/17/2022] Open
Abstract
The signaling mechanisms neurons use to modulate myelination of circuits in the central nervous system (CNS) are only partly understood. Through analysis of isoform-specific neuregulin1 (nrg1) mutants in zebrafish, we demonstrate that nrg1 type II is an important regulator of myelination of two classes of spinal cord interneurons. Surprisingly, nrg1 type II expression is prominent in unmyelinated Rohon-Beard sensory neurons, whereas myelination of neighboring interneurons is reduced in nrg1 type II mutants. Cell-type-specific loss-of-function studies indicate that nrg1 type II is required in Rohon-Beard neurons to signal to other neurons, not oligodendrocytes, to modulate spinal cord myelination. Together, our data support a model in which unmyelinated neurons express Nrg1 type II proteins to regulate myelination of neighboring neurons, a mode of action that may coordinate the functions of unmyelinated and myelinated neurons in the CNS.
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Affiliation(s)
- Daniel E Lysko
- Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
| | - William S Talbot
- Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA.
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3
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Khaje NA, Eletsky A, Biehn SE, Mobley CK, Rogals MJ, Kim Y, Mishra SK, Doerksen RJ, Lindert S, Prestegard JH, Sharp JS. Validated determination of NRG1 Ig-like domain structure by mass spectrometry coupled with computational modeling. Commun Biol 2022; 5:452. [PMID: 35551273 PMCID: PMC9098640 DOI: 10.1038/s42003-022-03411-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 04/25/2022] [Indexed: 01/03/2023] Open
Abstract
High resolution hydroxyl radical protein footprinting (HR-HRPF) is a mass spectrometry-based method that measures the solvent exposure of multiple amino acids in a single experiment, offering constraints for experimentally informed computational modeling. HR-HRPF-based modeling has previously been used to accurately model the structure of proteins of known structure, but the technique has never been used to determine the structure of a protein of unknown structure. Here, we present the use of HR-HRPF-based modeling to determine the structure of the Ig-like domain of NRG1, a protein with no close homolog of known structure. Independent determination of the protein structure by both HR-HRPF-based modeling and heteronuclear NMR was carried out, with results compared only after both processes were complete. The HR-HRPF-based model was highly similar to the lowest energy NMR model, with a backbone RMSD of 1.6 Å. To our knowledge, this is the first use of HR-HRPF-based modeling to determine a previously uncharacterized protein structure. A mass spectrometry-based method guides computational modeling for de novo protein structure prediction.
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Affiliation(s)
- Niloofar Abolhasani Khaje
- Department of BioMolecular Sciences, University of Mississippi, University, MS, USA.,Analytical Operations Department, Gilead Sciences, Foster City, CA, USA
| | - Alexander Eletsky
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
| | - Sarah E Biehn
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH, USA
| | - Charles K Mobley
- Department of BioMolecular Sciences, University of Mississippi, University, MS, USA.,Protein Discovery Department, Impossible Foods, Redwood City, CA, USA
| | - Monique J Rogals
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
| | - Yoonkyoo Kim
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
| | - Sushil K Mishra
- Department of BioMolecular Sciences, University of Mississippi, University, MS, USA.,Glycoscience Center of Research Excellence, University of Mississippi, University, MS, USA
| | - Robert J Doerksen
- Department of BioMolecular Sciences, University of Mississippi, University, MS, USA.,Glycoscience Center of Research Excellence, University of Mississippi, University, MS, USA
| | - Steffen Lindert
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH, USA
| | - James H Prestegard
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
| | - Joshua S Sharp
- Department of BioMolecular Sciences, University of Mississippi, University, MS, USA. .,Glycoscience Center of Research Excellence, University of Mississippi, University, MS, USA. .,Department of Chemistry and Biochemistry, University of Mississippi, University, MS, USA.
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4
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Dong Y, Qian L, Liu J. Molecular and cellular basis of embryonic cardiac chamber maturation. Semin Cell Dev Biol 2021; 118:144-149. [PMID: 33994094 DOI: 10.1016/j.semcdb.2021.04.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 04/12/2021] [Accepted: 04/26/2021] [Indexed: 10/21/2022]
Abstract
Heart malformation is the leading cause of human birth defects, and many of the congenital heart diseases (CHDs) originate from genetic defects that impact cardiac development and maturation. During development, the vertebrate heart undergoes a series of complex morphogenetic processes that increase its ability to pump blood. One of these processes leads to the formation of the sheet-like muscular projections called trabeculae. Trabeculae increase cardiac output and permit nutrition and oxygen uptake in the embryonic myocardium prior to coronary vascularization without increasing heart size. Cardiac trabeculation is also crucial for the development of the intraventricular fast conduction system. Alterations in cardiac trabecular development can manifest as a variety of congenital defects such as left ventricular noncompaction. In this review, we discuss the latest advances in understanding the molecular and cellular mechanisms underlying cardiac trabecular development.
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Affiliation(s)
- Yanhan Dong
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA; McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Li Qian
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA; McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jiandong Liu
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA; McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA.
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5
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Del Monte-Nieto G, Fischer JW, Gorski DJ, Harvey RP, Kovacic JC. Basic Biology of Extracellular Matrix in the Cardiovascular System, Part 1/4: JACC Focus Seminar. J Am Coll Cardiol 2020; 75:2169-2188. [PMID: 32354384 DOI: 10.1016/j.jacc.2020.03.024] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 02/27/2020] [Accepted: 03/03/2020] [Indexed: 01/12/2023]
Abstract
The extracellular matrix (ECM) is the noncellular component of tissues in the cardiovascular system and other organs throughout the body. It is formed of filamentous proteins, proteoglycans, and glycosaminoglycans, which extensively interact and whose structure and dynamics are modified by cross-linking, bridging proteins, and cleavage by matrix degrading enzymes. The ECM serves important structural and regulatory roles in establishing tissue architecture and cellular function. The ECM of the developing heart has unique properties created by its emerging contractile nature; similarly, ECM lining blood vessels is highly elastic in order to sustain the basal and pulsatile forces imposed on their walls throughout life. In this part 1 of a 4-part JACC Focus Seminar, we focus on the role, function, and basic biology of the ECM in both heart development and in the adult.
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Affiliation(s)
- Gonzalo Del Monte-Nieto
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria, Australia.
| | - Jens W Fischer
- Institut für Pharmakologie und Klinische Pharmakologie, University Hospital, Heinrich-Heine-University Düsseldorf, Germany; Cardiovascular Research Institute Düsseldorf, University Hospital, Heinrich-Heine-University Düsseldorf, Germany.
| | - Daniel J Gorski
- Institut für Pharmakologie und Klinische Pharmakologie, University Hospital, Heinrich-Heine-University Düsseldorf, Germany; Cardiovascular Research Institute Düsseldorf, University Hospital, Heinrich-Heine-University Düsseldorf, Germany
| | - Richard P Harvey
- Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; St. Vincent's Clinical School, University of New South Wales, Darlinghurst, New South Wales, Australia; School of Biotechnology and Biomolecular Science, University of New South Wales, New South Wales, Australia.
| | - Jason C Kovacic
- Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; St. Vincent's Clinical School, University of New South Wales, Darlinghurst, New South Wales, Australia; The Zena and Michael A. Wiener Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, New York.
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6
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Ledonne A, Mercuri NB. On the Modulatory Roles of Neuregulins/ErbB Signaling on Synaptic Plasticity. Int J Mol Sci 2019; 21:ijms21010275. [PMID: 31906113 PMCID: PMC6981567 DOI: 10.3390/ijms21010275] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 12/27/2019] [Accepted: 12/29/2019] [Indexed: 12/14/2022] Open
Abstract
Neuregulins (NRGs) are a family of epidermal growth factor-related proteins, acting on tyrosine kinase receptors of the ErbB family. NRGs play an essential role in the development of the nervous system, since they orchestrate vital functions such as cell differentiation, axonal growth, myelination, and synapse formation. They are also crucially involved in the functioning of adult brain, by directly modulating neuronal excitability, neurotransmission, and synaptic plasticity. Here, we provide a review of the literature documenting the roles of NRGs/ErbB signaling in the modulation of synaptic plasticity, focusing on evidence reported in the hippocampus and midbrain dopamine (DA) nuclei. The emerging picture shows multifaceted roles of NRGs/ErbB receptors, which critically modulate different forms of synaptic plasticity (LTP, LTD, and depotentiation) affecting glutamatergic, GABAergic, and DAergic synapses, by various mechanisms. Further, we discuss the relevance of NRGs/ErbB-dependent synaptic plasticity in the control of brain processes, like learning and memory and the known involvement of NRGs/ErbB signaling in the modulation of synaptic plasticity in brain’s pathological conditions. Current evidence points to a central role of NRGs/ErbB receptors in controlling glutamatergic LTP/LTD and GABAergic LTD at hippocampal CA3–CA1 synapses, as well as glutamatergic LTD in midbrain DA neurons, thus supporting that NRGs/ErbB signaling is essential for proper brain functions, cognitive processes, and complex behaviors. This suggests that dysregulated NRGs/ErbB-dependent synaptic plasticity might contribute to mechanisms underlying different neurological and psychiatric disorders.
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Affiliation(s)
- Ada Ledonne
- Department of Experimental Neuroscience, Santa Lucia Foundation, Via del Fosso di Fiorano, no 64, 00143 Rome, Italy;
- Correspondence: ; Tel.: +3906-501703160; Fax: +3906-501703307
| | - Nicola B. Mercuri
- Department of Experimental Neuroscience, Santa Lucia Foundation, Via del Fosso di Fiorano, no 64, 00143 Rome, Italy;
- Department of Systems Medicine, University of Rome “Tor Vergata”, Via Montpellier no 1, 00133 Rome, Italy
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7
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Swenarchuk LE. Nerve, Muscle, and Synaptogenesis. Cells 2019; 8:cells8111448. [PMID: 31744142 PMCID: PMC6912269 DOI: 10.3390/cells8111448] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 11/06/2019] [Accepted: 11/06/2019] [Indexed: 12/21/2022] Open
Abstract
The vertebrate skeletal neuromuscular junction (NMJ) has long served as a model system for studying synapse structure, function, and development. Over the last several decades, a neuron-specific isoform of agrin, a heparan sulfate proteoglycan, has been identified as playing a central role in synapse formation at all vertebrate skeletal neuromuscular synapses. While agrin was initially postulated to be the inductive molecule that initiates synaptogenesis, this model has been modified in response to work showing that postsynaptic differentiation can develop in the absence of innervation, and that synapses can form in transgenic mice in which the agrin gene is ablated. In place of a unitary mechanism for neuromuscular synapse formation, studies in both mice and zebrafish have led to the proposal that two mechanisms mediate synaptogenesis, with some synapses being induced by nerve contact while others involve the incorporation of prepatterned postsynaptic structures. Moreover, the current model also proposes that agrin can serve two functions, to induce synaptogenesis and to stabilize new synapses, once these are formed. This review examines the evidence for these propositions, and concludes that it remains possible that a single molecular mechanism mediates synaptogenesis at all NMJs, and that agrin acts as a stabilizer, while its role as inducer is open to question. Moreover, if agrin does not act to initiate synaptogenesis, it follows that as yet uncharacterized molecular interactions are required to play this essential inductive role. Several alternatives to agrin for this function are suggested, including focal pericellular proteolysis and integrin signaling, but all require experimental validation.
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8
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Kataria H, Alizadeh A, Karimi-Abdolrezaee S. Neuregulin-1/ErbB network: An emerging modulator of nervous system injury and repair. Prog Neurobiol 2019; 180:101643. [PMID: 31229498 DOI: 10.1016/j.pneurobio.2019.101643] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Revised: 06/07/2019] [Accepted: 06/11/2019] [Indexed: 12/20/2022]
Abstract
Neuregulin-1 (Nrg-1) is a member of the Neuregulin family of growth factors with essential roles in the developing and adult nervous system. Six different types of Nrg-1 (Nrg-1 type I-VI) and over 30 isoforms have been discovered; however, their specific roles are not fully determined. Nrg-1 signals through a complex network of protein-tyrosine kinase receptors, ErbB2, ErbB3, ErbB4 and multiple intracellular pathways. Genetic and pharmacological studies of Nrg-1 and ErbB receptors have identified a critical role for Nrg-1/ErbB network in neurodevelopment including neuronal migration, neural differentiation, myelination as well as formation of synapses and neuromuscular junctions. Nrg-1 signaling is best known for its characterized role in development and repair of the peripheral nervous system (PNS) due to its essential role in Schwann cell development, survival and myelination. However, our knowledge of the impact of Nrg-1/ErbB on the central nervous system (CNS) has emerged in recent years. Ongoing efforts have uncovered a multi-faceted role for Nrg-1 in regulating CNS injury and repair processes. In this review, we provide a timely overview of the most recent updates on Nrg-1 signaling and its role in nervous system injury and diseases. We will specifically highlight the emerging role of Nrg-1 in modulating the glial and immune responses and its capacity to foster neuroprotection and remyelination in CNS injury. Nrg-1/ErbB network is a key regulatory pathway in the developing nervous system; therefore, unraveling its role in neuropathology and repair can aid in development of new therapeutic approaches for nervous system injuries and associated disorders.
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Affiliation(s)
- Hardeep Kataria
- Department of Physiology and Pathophysiology, Regenerative Medicine Program, Spinal Cord Research Centre, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Arsalan Alizadeh
- Department of Physiology and Pathophysiology, Regenerative Medicine Program, Spinal Cord Research Centre, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Soheila Karimi-Abdolrezaee
- Department of Physiology and Pathophysiology, Regenerative Medicine Program, Spinal Cord Research Centre, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada.
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9
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Liu J, Allender E, Wang J, Simpson EH, Loeb JA, Song F. Slowing disease progression in the SOD1 mouse model of ALS by blocking neuregulin-induced microglial activation. Neurobiol Dis 2017; 111:118-126. [PMID: 29278738 DOI: 10.1016/j.nbd.2017.12.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 11/05/2017] [Accepted: 12/19/2017] [Indexed: 12/13/2022] Open
Abstract
There are no effective treatments to slow disease progression in ALS. We previously reported that neuregulin (NRG) receptors are constitutively activated on microglia in the ventral horns in both ALS patients and SOD1 mice and in the corticospinal tracts of ALS patients, and that NRG receptor activation occurs prior to significant clinical disease onset in SOD1 mice. Here, we hypothesize that blocking NRG signaling on microglia would slow disease progression in SOD1 mice using a targeted NRG antagonist (HBD-S-H4). Recombinant HBD-S-H4 directly delivered into the central nervous system (CNS) through implanted intracerebroventricular cannulas showed no signs of toxicity and significantly inhibited NRG receptor activation on microglia resulting in reduced microglial activation and motor neuron loss. The treatment also resulted in a delay in disease onset and an increase in survival. The therapeutic effect was dose-dependent that varied as a function of genetic background in two different strains of SOD1 mice. As a complementary drug delivery approach, transgenic mice expressing HBD-S-H4 driven by an astrocytic promoter (GFAP) had slower disease progression in a dose dependent manner, based on the level of HBD-S-H4 expression. These studies provide mechanistic insights into how NRG signaling on microglia may lead to disease progression and demonstrate the utility of a humanized fusion protein that blocks NRG as a novel therapeutic for human ALS.
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Affiliation(s)
- Jianguo Liu
- Department of Neurology and Rehabilitation, University of Illinois at Chicago, IL 60612, United States
| | - Elise Allender
- Department of Neurology and Rehabilitation, University of Illinois at Chicago, IL 60612, United States
| | - Jiajing Wang
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, United States
| | - Eleanor H Simpson
- Department of Psychiatry, Columbia University, New York, NY 10032, United States
| | - Jeffrey A Loeb
- Department of Neurology and Rehabilitation, University of Illinois at Chicago, IL 60612, United States
| | - Fei Song
- Department of Neurology and Rehabilitation, University of Illinois at Chicago, IL 60612, United States.
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10
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Wang J, Song F, Loeb JA. Neuregulin1 fine-tunes pre-, post-, and perisynaptic neuromuscular junction development. Dev Dyn 2017; 246:368-380. [PMID: 28245533 DOI: 10.1002/dvdy.24494] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 02/13/2017] [Accepted: 02/16/2017] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Neuromuscular junction (NMJ) development is a multistep process mediated by coordinated interactions between the nerve terminal, target muscle, and perisynaptic Schwann cell that require constant back-and-forth communication. Retrograde and anterograde growth and differentiation factors have been postulated to participate in this communication. While neuregulin1 (NRG1) has been shown to be potent anterograde signal that activates acetylcholine receptor (AChR) transcription and clustering in vitro, its roles in NMJ development in vivo remain elusive. RESULTS Using the model of chicken embryo, we measured the effects of NRG1 signaling during NMJ development in ovo using quantitative, sequential measures of AChR cluster size and density, pre- and postsynaptic apposition, and the alignment of perisynaptic Schwann cells. Using in ovo electroporation at early stages and a targeted soluble neuregulin antagonist through all developmental stages, we found soluble NRG1 regulates AChR cluster density and size at the earliest stage prior to nerve-AChR cluster contact. Once the nerve contacts with muscle AChRs, NRG1 has pronounced effects on presynaptic specialization and on the alignment of perisynaptic Schwann cells at endplates. CONCLUSION These findings suggest that, while NRG1 may not be critical for overall development, it appears to be important in fine-tuning pre-, post-, and perisynaptic development of the NMJ. Developmental Dynamics 246:368-380, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Jiajing Wang
- The Center for Molecular Medicine & Genetics, Wayne State University School of Medicine, Detroit, Michigan
| | - Fei Song
- Department of Neurology and Rehabilitation, The University of Illinois at Chicago, Chicago, Illinois
| | - Jeffrey A Loeb
- Department of Neurology and Rehabilitation, The University of Illinois at Chicago, Chicago, Illinois
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11
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Lenihan DJ, Anderson SA, Lenneman CG, Brittain E, Muldowney JA, Mendes L, Zhao PZ, Iaci J, Frohwein S, Zolty R, Eisen A, Sawyer DB, Caggiano AO. A Phase I, Single Ascending Dose Study of Cimaglermin Alfa (Neuregulin 1β3) in Patients With Systolic Dysfunction and Heart Failure. JACC Basic Transl Sci 2016; 1:576-586. [PMID: 30167542 PMCID: PMC6113538 DOI: 10.1016/j.jacbts.2016.09.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 09/27/2016] [Accepted: 09/28/2016] [Indexed: 01/03/2023]
Abstract
A first-in-human, phase 1, double blind, placebo-controlled, single ascending dose study examined the safety, tolerability, and exploratory efficacy of intravenous infusion of a recombinant growth factor, cimaglermin alfa, in patients with heart failure and left ventricular systolic dysfunction (LVSD). In these patients on optimal guideline-directed medical therapy, cimaglermin treatment was generally tolerated except for transient nausea and headache and a dose-limiting toxicity was noted at the highest planned dose. There was a dose-dependent improvement in left ventricular ejection fraction lasting 90 days following infusion. Thus, cimaglermin is a potential therapy to enhance cardiac function in LVSD and warrants further investigation.
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Key Words
- AE, adverse event
- AUC, area under the curve
- DLT, dose-limiting toxicity
- GGF, glial growth factor
- HF, heart failure
- LVEF, left ventricular ejection fraction
- LVSD, left ventricular systolic dysfunction
- NRG, neuregulin
- NYHA, New York Heart Association functional class
- TEAE, treatment-emergent adverse event
- cardiac repair
- growth factor
- neuregulin
- systolic dysfunction
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Affiliation(s)
- Daniel J. Lenihan
- Division of Cardiovascular Medicine, Vanderbilt University, Nashville, Tennessee
| | - Sarah A. Anderson
- Division of Cardiovascular Medicine, Vanderbilt University, Nashville, Tennessee
| | | | - Evan Brittain
- Division of Cardiovascular Medicine, Vanderbilt University, Nashville, Tennessee
| | - James A.S. Muldowney
- Division of Cardiovascular Medicine, Vanderbilt University, Nashville, Tennessee
| | - Lisa Mendes
- Division of Cardiovascular Medicine, Vanderbilt University, Nashville, Tennessee
| | | | | | - Stephen Frohwein
- Emory Heart and Vascular Center at Emory Saint Joseph’s, Atlanta, Georgia
| | - Ronald Zolty
- University of Nebraska Medical Center, Omaha, Nebraska
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12
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Kamezaki A, Sato F, Aoki K, Asakawa K, Kawakami K, Matsuzaki F, Sehara-Fujisawa A. Visualization of Neuregulin 1 ectodomain shedding reveals its local processing in vitro and in vivo. Sci Rep 2016; 6:28873. [PMID: 27364328 PMCID: PMC4929465 DOI: 10.1038/srep28873] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 06/09/2016] [Indexed: 11/17/2022] Open
Abstract
Neuregulin1 (NRG1) plays diverse developmental roles and is likely involved in several neurological disorders including schizophrenia. The transmembrane NRG1 protein is proteolytically cleaved and released as a soluble ligand for ErbB receptors. Such post-translational processing, referred to as 'ectodomain shedding', is thought to be crucial for NRG1 function. However, little is known regarding the regulatory mechanism of NRG1 cleavage in vivo. Here, we developed a fluorescent probe, NRG1 Cleavage Indicating SenSOR (N-CISSOR), by fusing mCherry and GFP to the extracellular and intracellular domains of NRG1, respectively. N-CISSOR mimicked the subcellular localization and biochemical properties of NRG1 including cleavage dynamics and ErbB phosphorylation in cultured cells. mCherry/GFP ratio imaging of phorbol-12-myristate-13-acetate-stimulated N-CISSOR-expressing HEK293T cells enabled to monitor rapid ectodomain shedding of NRG1 at the subcellular level. Utilizing N-CISSOR in zebrafish embryos revealed preferential axonal NRG1 ectodomain shedding in developing motor neurons, demonstrating that NRG1 ectodomain shedding is spatially regulated at the subcellular level. Thus, N-CISSOR will be a valuable tool for elucidating the spatiotemporal regulation of NRG1 ectodomain shedding, both in vitro and in vivo.
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Affiliation(s)
- Aosa Kamezaki
- Department of Animal Development and Physiology, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Fuminori Sato
- Department of Growth Regulation, Institute for Frontier Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
| | - Kazuhiro Aoki
- Imaging Platform for Spatio-Temporal Information, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Kazuhide Asakawa
- Division of Molecular and Developmental Biology, National Institute of Genetics, and Department of Genetics, SOKENDAI, Graduate University for Advanced Studies, Mishima, Shizuoka 411-8540, Japan
| | - Koichi Kawakami
- Division of Molecular and Developmental Biology, National Institute of Genetics, and Department of Genetics, SOKENDAI, Graduate University for Advanced Studies, Mishima, Shizuoka 411-8540, Japan
| | - Fumio Matsuzaki
- Laboratory of Cell Asymmetry, RIKEN Center of Developmental Biology, Kobe 650-0047, Japan
| | - Atsuko Sehara-Fujisawa
- Department of Growth Regulation, Institute for Frontier Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
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13
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Hatakeyama J, Wald JH, Rafidi H, Cuevas A, Sweeney C, Carraway KL. The ER structural protein Rtn4A stabilizes and enhances signaling through the receptor tyrosine kinase ErbB3. Sci Signal 2016; 9:ra65. [PMID: 27353365 DOI: 10.1126/scisignal.aaf1604] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
ErbB3 and ErbB4 are receptor tyrosine kinases that are activated by the neuregulin (NRG) family of growth factors. These receptors govern various developmental processes, and their dysregulation contributes to several human disease states. The abundance of ErbB3 and ErbB4, and thus signaling through these receptors, is limited by the E3 ubiquitin ligase Nrdp1, which targets ErbB3 and ErbB4 for degradation. Reticulons are proteins that influence the morphology of the endoplasmic reticulum (ER) by promoting the formation of tubules, a response of cells to some stressors. We found that the ER structural protein reticulon 4A (Rtn4A, also known as Nogo-A) increased ErbB3 abundance and proliferative signaling by suppressing Nrdp1 function. Rtn4A interacted with Nrdp1 and stabilized ErbB3 in an Nrdp1-dependent manner. Rtn4A overexpression induced the redistribution of Nrdp1 from a cytosolic or perinuclear localization to ER tubules. Rtn4A knockdown in human breast tumor cells decreased ErbB3 abundance, NRG-stimulated signaling, and cellular proliferation and migration. Because proteins destined for the plasma membrane are primarily synthesized in the sheet portions of the ER, our observations suggest that Rtn4A counteracts the Nrdp1-mediated degradation of ErbB3 by sequestering the ubiquitin ligase into ER tubules. The involvement of a reticulon suggests a molecular link between ER structure and the sensitivity of cells to receptor tyrosine kinase-mediated survival signals at the cell surface.
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Affiliation(s)
- Jason Hatakeyama
- Department of Biochemistry and Molecular Medicine, and UC Davis Comprehensive Cancer Center, UC Davis School of Medicine, Sacramento, CA 95817, USA
| | - Jessica H Wald
- Department of Biochemistry and Molecular Medicine, and UC Davis Comprehensive Cancer Center, UC Davis School of Medicine, Sacramento, CA 95817, USA
| | - Hanine Rafidi
- Department of Biochemistry and Molecular Medicine, and UC Davis Comprehensive Cancer Center, UC Davis School of Medicine, Sacramento, CA 95817, USA
| | - Antonio Cuevas
- Department of Biochemistry and Molecular Medicine, and UC Davis Comprehensive Cancer Center, UC Davis School of Medicine, Sacramento, CA 95817, USA
| | - Colleen Sweeney
- Department of Biochemistry and Molecular Medicine, and UC Davis Comprehensive Cancer Center, UC Davis School of Medicine, Sacramento, CA 95817, USA
| | - Kermit L Carraway
- Department of Biochemistry and Molecular Medicine, and UC Davis Comprehensive Cancer Center, UC Davis School of Medicine, Sacramento, CA 95817, USA.
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Eshed-Eisenbach Y, Gordon A, Sukhanov N, Peles E. Specific inhibition of secreted NRG1 types I-II by heparin enhances Schwann Cell myelination. Glia 2016; 64:1227-34. [PMID: 27143444 DOI: 10.1002/glia.22995] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 04/13/2016] [Indexed: 12/25/2022]
Abstract
Primary cultures of mixed neuron and Schwann cells prepared from dorsal root ganglia (DRG) are extensively used as a model to study myelination. These dissociated DRG cultures have the particular advantage of bypassing the difficulty in purifying mouse Schwann cells, which is often required when using mutant mice. However, the drawback of this experimental system is that it yields low amounts of myelin. Here we report a simple and efficient method to enhance myelination in vitro. We show that the addition of heparin or low molecular weight heparin to mixed DRG cultures markedly increases Schwann cells myelination. The myelin promoting activity of heparin results from specific inhibition of the soluble immunoglobulin (Ig)-containing isoforms of neuregulin 1 (i.e., NRG1 types I and II) that negatively regulates myelination. Heparin supplement provides a robust and reproducible method to increase myelination in a simple and commonly used culture system. GLIA 2016;64:1227-1234.
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Affiliation(s)
- Yael Eshed-Eisenbach
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Aaron Gordon
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Natalya Sukhanov
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Elior Peles
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
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15
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Chang KA, Shin KY, Nam E, Lee YB, Moon C, Suh YH, Lee SH. Plasma soluble neuregulin-1 as a diagnostic biomarker for Alzheimer's disease. Neurochem Int 2016; 97:1-7. [PMID: 27133777 DOI: 10.1016/j.neuint.2016.04.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 04/12/2016] [Accepted: 04/26/2016] [Indexed: 01/14/2023]
Abstract
To identify some apparent biomarker candidates for the diagnosis of Alzheimer's disease (AD) pathology, we investigated whether there would be a significant difference between the levels of the plasma proteins of AD patients and healthy people. A total of 115 subjects were enrolled, 60 individuals with AD and 55 healthy controls. There was a statistical difference in the mini-mental status exam (MMSE) scores and the clinical dementia rating (CDR) scores between the two groups. We used the immunoblotting assay to analyze several plasma proteins in the subjects. Amyloid-β (Aβ), S100a9, and soluble neuregulin-1 (sNRG-1), including α-synuclein (α-Syn) as a detection control were detected in the plasma samples. Unlike Aβ, S100a9 and α-Syn, the level of sNRG-1 of the AD patients was significantly higher than that of the healthy control subjects. The AD patients were divided into mild and moderate groups according to their MMSE and CDR scores. We found a significant correlation between the level of sNRG-1 and MMSE scores. The sNRG-1 level was significantly higher in mild AD patients as well as in moderate AD patients compared with that of the control subjects. These new findings indicate that increased plasma sNRG-1 levels might be a novel and reliable biological marker for the early diagnosis of AD.
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Affiliation(s)
- Keun-A Chang
- Department of Pharmacology, College of Medicine, Neuroscience Research Institute, Gachon University, Incheon, 406-799, South Korea
| | - Ki Young Shin
- Department of Microbiology, College of Natural Science, Dankook University, Cheonan-si, Chungnam, 330-714, South Korea
| | - Eunjoo Nam
- Department of Pharmacology, College of Medicine, Neuroscience Research Institute, Gachon University, Incheon, 406-799, South Korea
| | - Yeong-Bae Lee
- Department of Neurology, Gil Medical Center, Gachon University, Incheon, 405-760, South Korea
| | - Cheil Moon
- Department of Brain Science, Graduate School, Daegu Gyeungbuk Institute of Science and Technology, Daegu, 711-873, South Korea
| | - Yoo-Hun Suh
- Department of Pharmacology, College of Medicine, Neuroscience Research Institute, Gachon University, Incheon, 406-799, South Korea.
| | - Sang Hyung Lee
- Department of Neurosurgery, SMG-SNU Boramae Medical Center, Seoul National University College of Medicine, Seoul, 110-799, South Korea.
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16
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Thomas JT, Chhuy-Hy L, Andrykovich KR, Moos M. SMOC Binds to Pro-EGF, but Does Not Induce Erk Phosphorylation via the EGFR. PLoS One 2016; 11:e0154294. [PMID: 27101391 PMCID: PMC4839742 DOI: 10.1371/journal.pone.0154294] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 04/12/2016] [Indexed: 12/20/2022] Open
Abstract
In an attempt to identify the cell-associated protein(s) through which SMOC (Secreted Modular Calcium binding protein) induces mitogen-activated protein kinase (MAPK) signaling, the epidermal growth factor receptor (EGFR) became a candidate. However, although in 32D/EGFR cells, the EGFR was phosphorylated in the presence of a commercially available human SMOC-1 (hSMOC-1), only minimal phosphorylation was observed in the presence of Xenopus SMOC-1 (XSMOC-1) or human SMOC-2. Analysis of the commercial hSMOC-1 product demonstrated the presence of pro-EGF as an impurity. When the pro-EGF was removed, only minimal EGFR activation was observed, indicating that SMOC does not signal primarily through EGFR and its receptor remains unidentified. Investigation of SMOC/pro-EGF binding affinity revealed a strong interaction that does not require the C-terminal extracellular calcium-binding (EC) domain of SMOC or the EGF domain of pro-EGF. SMOC does not appear to potentiate or inhibit MAPK signaling in response to pro-EGF, but the interaction could provide a mechanism for retaining soluble pro-EGF at the cell surface.
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Affiliation(s)
- J. Terrig Thomas
- FDA/Center for Biologics Evaluation and Research, Division of Cellular and Gene Therapies Office of Cellular, Tissue, and Gene Therapies, Silver Spring, MD, United States of America
- * E-mail:
| | - Lina Chhuy-Hy
- FDA/Center for Biologics Evaluation and Research, Division of Cellular and Gene Therapies Office of Cellular, Tissue, and Gene Therapies, Silver Spring, MD, United States of America
| | - Kristin R. Andrykovich
- FDA/Center for Biologics Evaluation and Research, Division of Cellular and Gene Therapies Office of Cellular, Tissue, and Gene Therapies, Silver Spring, MD, United States of America
| | - Malcolm Moos
- FDA/Center for Biologics Evaluation and Research, Division of Cellular and Gene Therapies Office of Cellular, Tissue, and Gene Therapies, Silver Spring, MD, United States of America
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17
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Song F, Chiang P, Ravits J, Loeb JA. Activation of microglial neuregulin1 signaling in the corticospinal tracts of ALS patients with upper motor neuron signs. Amyotroph Lateral Scler Frontotemporal Degener 2013; 15:77-83. [DOI: 10.3109/21678421.2013.853802] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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18
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The tanapoxvirus 15L protein is a virus-encoded neuregulin that promotes viral replication in human endothelial cells. J Virol 2012; 87:3018-26. [PMID: 23269801 DOI: 10.1128/jvi.02112-12] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Studies on large double-stranded DNA (dsDNA) viruses such as poxviruses have been helpful in identifying a number of viral and cellular growth factors that contribute to our broad understanding of virus-host interaction. Orthopoxviruses and leporipoxviruses are among the most studied viruses in this aspect. However, tanapoxvirus (TPV), a member of the genus Yatapoxvirus, still remains largely unexplored, as the only known hosts for this virus are humans and monkeys. Here, we describe the initial characterization of an epidermal growth factor (EGF)-like growth factor mimicking human neuregulin from TPV, expressed by the TPV-15L gene. Assays using a baculovirus-expressed and tagged TPV-15L protein demonstrated the ability to phosphorylate neuregulin receptors. Neuregulins represent a large family of EGF-like growth factors that play important roles in embryonic endocardium development, Schwann and oligodendrocyte survival and differentiation, localized acetylcholine receptor expression at the neuromuscular junction, and epithelial morphogenesis. Interestingly, certain neuregulin molecules are able to target specific tissues through interactions with heparin sulfate proteoglycans via an immunoglobulin (Ig)-like domain. Analyses of TPV-15L revealed no Ig-like domain, but it retains the ability to bind heparin and phosphorylate neuregulin receptors, providing compelling evidence that TPV-15L is a functional mimetic of neuregulin. TPV-15L knockout virus experiments demonstrate that the virus replicates in human umbilical vein endothelial cells less efficiently than wild-type TPV-Kenya, indicating that this is a nonessential protein for virus viability but can serve a stimulatory role for replication in some cultured cells. However, the precise role of this protein in host-virus interaction still remains to be deduced.
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19
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Butchar JP, Cain D, Manivannan SN, McCue AD, Bonanno L, Halula S, Truesdell S, Austin CL, Jacobsen TL, Simcox A. New negative feedback regulators of Egfr signaling in Drosophila. Genetics 2012; 191:1213-26. [PMID: 22595244 PMCID: PMC3416002 DOI: 10.1534/genetics.112.141093] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 05/07/2012] [Indexed: 12/18/2022] Open
Abstract
The highly conserved epidermal growth factor receptor (Egfr) pathway is required in all animals for normal development and homeostasis; consequently, aberrant Egfr signaling is implicated in a number of diseases. Genetic analysis of Drosophila melanogaster Egfr has contributed significantly to understanding this conserved pathway and led to the discovery of new components and targets. Here we used microarray analysis of third instar wing discs, in which Egfr signaling was perturbed, to identify new Egfr-responsive genes. Upregulated transcripts included five known targets, suggesting the approach was valid. We investigated the function of 29 previously uncharacterized genes, which had pronounced responses. The Egfr pathway is important for wing-vein patterning and using reverse genetic analysis we identified five genes that showed venation defects. Three of these genes are expressed in vein primordia and all showed transcriptional changes in response to altered Egfr activity consistent with being targets of the pathway. Genetic interactions with Egfr further linked two of the genes, Sulfated (Sulf1), an endosulfatase gene, and CG4096, an A Disintegrin And Metalloproteinase with ThromboSpondin motifs (ADAMTS) gene, to the pathway. Sulf1 showed a strong genetic interaction with the neuregulin-like ligand vein (vn) and may influence binding of Vn to heparan-sulfated proteoglycans (HSPGs). How Drosophila Egfr activity is modulated by CG4096 is unknown, but interestingly vertebrate EGF ligands are regulated by a related ADAMTS protein. We suggest Sulf1 and CG4096 are negative feedback regulators of Egfr signaling that function in the extracellular space to influence ligand activity.
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Affiliation(s)
- Jonathan P. Butchar
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210
| | - Donna Cain
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210
| | | | - Andrea D. McCue
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210
| | - Liana Bonanno
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210
| | - Sarah Halula
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210
| | - Sharon Truesdell
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210
| | - Christina L. Austin
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210
| | - Thomas L. Jacobsen
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210
| | - Amanda Simcox
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210
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20
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Choi W, Kolbe L, Hearing VJ. Characterization of the bioactive motif of neuregulin-1, a fibroblast-derived paracrine factor that regulates the constitutive color and the function of melanocytes in human skin. Pigment Cell Melanoma Res 2012; 25:477-81. [PMID: 22494484 DOI: 10.1111/j.1755-148x.2012.01002.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Interactions between melanocytes and neighboring cells in the skin (keratinocytes and fibroblasts) play important roles in regulating human skin color. We recently reported that neuregulin-1 (NRG1) is highly expressed in fibroblasts from Fitzpatrick type VI skin (the darkest) and at least in part determines the constitutive color of human skin. We have now characterized the bioactive motif of NRG1 that is involved in modulating melanin production in human melanocytes. We found that 8-mer motifs (PSRYLCKC and LCKCPNEF) increased melanin production but did not increase the proliferation of melanocytes; the minimum fragment that could elicit that effect was the tetrapeptide LCKC. This smaller bioactive peptide might have an advantage in clinical applications in which it modulates only pigmentation and does not stimulate melanocyte proliferation.
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Affiliation(s)
- Wonseon Choi
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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21
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Autism-like socio-communicative deficits and stereotypies in mice lacking heparan sulfate. Proc Natl Acad Sci U S A 2012; 109:5052-6. [PMID: 22411800 DOI: 10.1073/pnas.1117881109] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Heparan sulfate regulates diverse cell-surface signaling events, and its roles in the development of the nervous system recently have been increasingly uncovered by studies using genetic models carrying mutations of genes encoding enzymes for its synthesis. On the other hand, the role of heparan sulfate in the physiological function of the adult brain has been poorly characterized, despite several pieces of evidence suggesting its role in the regulation of synaptic function. To address this issue, we eliminated heparan sulfate from postnatal neurons by conditionally inactivating Ext1, the gene encoding an enzyme essential for heparan sulfate synthesis. Resultant conditional mutant mice show no detectable morphological defects in the cytoarchitecture of the brain. Remarkably, these mutant mice recapitulate almost the full range of autistic symptoms, including impairments in social interaction, expression of stereotyped, repetitive behavior, and impairments in ultrasonic vocalization, as well as some associated features. Mapping of neuronal activation by c-Fos immunohistochemistry demonstrates that neuronal activation in response to social stimulation is attenuated in the amygdala in these mice. Electrophysiology in amygdala pyramidal neurons shows an attenuation of excitatory synaptic transmission, presumably because of the reduction in the level of synaptically localized AMPA-type glutamate receptors. Our results demonstrate that heparan sulfate is critical for normal functioning of glutamatergic synapses and that its deficiency mediates socio-communicative deficits and stereotypies characteristic for autism.
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22
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Abstract
Neuregulin 1 (NRG1) is a neuron-derived trophic molecule that supports axoglial and neuromuscular development through several alternatively spliced isoforms; its possible role in the pathogenesis and progression of amyotrophic lateral sclerosis (ALS) is not known. We analyzed the relationship of NRG1 isoform expression to glial cell activation and motor neuron loss in spinal cords of ALS patients and during disease progression in the superoxide dismutase 1 (SOD1) ALS mouse model. Microgliosis, astrocytosis, and motor neuron loss were observed in the ventral horns in ALS patients and were increased in SOD1 mice along with disease progression. Type III (membrane-bound) NRG1 expression was reduced in parallel with motor neuron loss, but Type I (secreted) NRG1 expression was increased and was associated with glial activation. Increased NRG1 receptor activation was observed on activated microglia in both ALS patients and in SOD1 mice. This activation was observed at the time of disease onset and before upregulation of NRG1 gene expression in the mice. The downregulation of membrane-bound Type III NRG1 forms may reflect motor neuron loss, but increased signaling by secreted-type NRG1 isoforms could contribute to disease pathogenesis through glial cell activation. NRG1 might, therefore, represent a novel therapeutic target against disease progression in ALS.
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23
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Ngo ST, Cole RN, Sunn N, Phillips WD, Noakes PG. Neuregulin-1 potentiates agrin-induced acetylcholine receptor clustering through muscle-specific kinase phosphorylation. J Cell Sci 2012; 125:1531-43. [PMID: 22328506 DOI: 10.1242/jcs.095109] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
At neuromuscular synapses, neural agrin (n-agrin) stabilizes embryonic postsynaptic acetylcholine receptor (AChR) clusters by signalling through the muscle-specific kinase (MuSK) complex. Live imaging of cultured myotubes showed that the formation and disassembly of primitive AChR clusters is a dynamic and reversible process favoured by n-agrin, and possibly other synaptic signals. Neuregulin-1 is a growth factor that can act through muscle ErbB receptor kinases to enhance synaptic gene transcription. Recent studies suggest that neuregulin-1-ErbB signalling can modulate n-agrin-induced AChR clustering independently of its effects on transcription. Here we report that neuregulin-1 increased the size of developing AChR clusters when injected into muscles of embryonic mice. We investigated this phenomenon using cultured myotubes, and found that in the ongoing presence of n-agrin, neuregulin-1 potentiates AChR clustering by increasing the tyrosine phosphorylation of MuSK. This potentiation could be blocked by inhibiting Shp2, a postsynaptic tyrosine phosphatase known to modulate the activity of MuSK. Our results provide new evidence that neuregulin-1 modulates the signaling activity of MuSK and hence might function as a second-order regulator of postsynaptic AChR clustering at the neuromuscular synapse. Thus two classic synaptic signalling systems (neuregulin-1 and n-agrin) converge upon MuSK to regulate postsynaptic differentiation.
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Affiliation(s)
- Shyuan T Ngo
- School of Biomedical Sciences, University of Queensland, St. Lucia, 4072, Queensland, Australia
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24
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Fricker FR, Bennett DL. The role of neuregulin-1 in the response to nerve injury. FUTURE NEUROLOGY 2011; 6:809-822. [PMID: 22121335 DOI: 10.2217/fnl.11.45] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Axons and Schwann cells exist in a highly interdependent relationship: damage to one cell type invariably leads to pathophysiological changes in the other. Greater understanding of communication between these cell types will not only give insight into peripheral nerve development, but also the reaction to and recovery from peripheral nerve injury. The type III isoform of neuregulin-1 (NRG1) has emerged as a key signaling factor that is expressed on axons and, through binding to erbB2/3 receptors on Schwann cells, regulates multiple phases of their development. In adulthood, NRG1 is dispensable for the maintenance of the myelin sheath; however, this factor is required for both axon regeneration and remyelination following nerve injury. The outcome of NRG1 signaling depends on interactions with other pathways within Schwann cells such as Notch, integrin and cAMP signaling. In certain circumstances, this signaling pathway may be maladaptive; for instance, direct binding of Mycobacterium leprae onto erbB2 receptors produces excessive activation and can actually promote demyelination. Attempts to modulate this pathway in order to promote nerve repair will therefore need to give consideration to the exact isoform used, as well as how it is processed and the context in which it is presented to the Schwann cell.
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Critical period of axoglial signaling between neuregulin-1 and brain-derived neurotrophic factor required for early Schwann cell survival and differentiation. J Neurosci 2011; 31:9630-40. [PMID: 21715628 DOI: 10.1523/jneurosci.1659-11.2011] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
During peripheral nervous system development, successful communication between axons and Schwann cells is required for proper function of both myelinated and nonmyelinated nerve fibers. Alternatively spliced proteins belonging to the neuregulin1 (NRG1) gene family of growth and differentiation factors are essential for Schwann cell survival and peripheral nerve development. Although recent studies have strongly implicated membrane-bound NRG1 forms (type III) in the myelination at late stages, little is known about the role of soluble, heparin-binding forms of NRG1 (type I/II) in regulating early Schwann cell development in vivo. These forms are rapidly released from axons in vitro by Schwann-cell-secreted neurotrophic factors and, unlike membrane-bound forms, have a unique ability to diffuse and adhere to heparan sulfate-rich cell surfaces. Here, we show that axon-derived soluble NRG1 translocates from axonal to Schwann cell surfaces in the embryonic chick between days 5 and 7, corresponding to the critical period of Schwann cell survival. Downregulating endogenous type I/II NRG1 signaling either with a targeted NRG1 antagonist or by shRNA blocks their differentiation from precursors into immature Schwann cells and increases programmed cell death, whereas upregulating NRG1 rescues Schwann cells. Exogenous BDNF also promotes Schwann cell survival through promoting the local release of axonal NRG1. Consistently, increased Schwann cell death occurs both in trkB knock-out mice and after knocking down axonal trkB in chick embryos, which can then be rescued with soluble NRG1. These findings suggest a localized, axoglial feedback loop through soluble NRG1 and BDNF critical for early Schwann cell survival and differentiation.
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26
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Rösler TW, Depboylu C, Arias-Carrión O, Wozny W, Carlsson T, Höllerhage M, Oertel WH, Schrattenholz A, Höglinger GU. Biodistribution and brain permeability of the extracellular domain of neuregulin-1-β1. Neuropharmacology 2011; 61:1413-8. [PMID: 21903113 DOI: 10.1016/j.neuropharm.2011.08.033] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 07/26/2011] [Accepted: 08/19/2011] [Indexed: 10/17/2022]
Abstract
Neuregulin-1 (NRG1) belongs to a large family of growth and differentiation factors with a key role in the development and maintenance of the brain. Genetic association of NRG1 within brain disorders such as Alzheimer's disease, schizophrenia and neuroprotective properties of certain NRG1 isoforms have led to a variety of studies in corresponding disease models. In the present work, we investigated NRG1 with regard to its peripheral and central biodistribution after systemic application. We first-time radiolabeled the entire biologically active extracellular domain of NRG1 isotype-β1 (NRG1-β1 ECD; aa 2-246) with iodine-125 and administered it peripherally to healthy adult C57Bl6 mice. Blood kinetics and relative organ distribution of (125)I-labeled NRG1-β1 ECD were determined. The blood level of NRG1-β1 ECD peaked within the first hour after intraperitoneal (i.p.) application. The brain-blood ratios of (125)I-labeled NRG1-β1 ECD were time-dependently 150-370% higher compared to the brain impermeable control, (131)I-labeled bovine serum albumin. Autoradiographs of brain slices demonstrated that (125)I-labeled NRG1-β1 ECD accumulated in several regions of the brain e.g. frontal cortex, striatum and ventral midbrain containing the substantia nigra. In addition we found histochemical and biochemical evidence that phosphorylation of the NRG1 prototype receptor ErbB4 was increased in these regions after systemic application of NRG1-β1 ECD. Our data suggest that NRG1-β1 ECD passes the blood-brain barrier and activates cerebral ErbB4 receptors.
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Affiliation(s)
- Thomas W Rösler
- Experimental Neurology, Department of Neurology, Philipps University, Marburg, Germany
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27
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Neuregulin-1 signals from the periphery regulate AMPA receptor sensitivity and expression in GABAergic interneurons in developing neocortex. J Neurosci 2011; 31:5699-709. [PMID: 21490211 DOI: 10.1523/jneurosci.3477-10.2011] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neuregulin-1 (NRG1) signaling is thought to contribute to both neuronal development and schizophrenia neuropathology. Here, we describe the developmental effects of excessive peripheral NRG1 signals on synaptic activity and AMPA receptor expression of GABAergic interneurons in postnatal rodent neocortex. A core peptide common to all NRG1 variants (eNRG1) was subcutaneously administered to mouse pups. Injected eNRG1 penetrated the blood-brain barrier and activated ErbB4 NRG1 receptors in the neocortex, in which ErbB4 mRNA is predominantly expressed by parvalbumin-positive GABAergic interneurons. We prepared neocortical slices from juvenile mice that were receiving eNRG1 subchronically and recorded inhibitory synaptic activity from layer V pyramidal neurons. Postnatal eNRG1 treatment significantly enhanced polysynaptic IPSCs, although monosynaptic IPSCs were not affected. Examination of excitatory inputs to parvalbumin-containing GABAergic interneurons revealed that eNRG1 treatment significantly increased AMPA-triggered inward currents and the amplitudes and frequencies of miniature EPSCs (mEPSCs). Similar effects on mEPSCs were observed in mice treated with a soluble, full-length form of NRG1 type I. Consistent with the electrophysiologic data, expression of the AMPA receptor GluA1 (i.e., GluR1, GluRA) was upregulated in the postsynaptic density/cytoskeletal fraction prepared from eNRG1-treated mouse neocortices. Cortical GABAergic neurons cultured with eNRG1 exhibited a significant increase in surface GluA1 immunoreactivity at putative synaptic sites on their dendrites. These results indicate that NRG1 circulating in the periphery influences postnatal development of synaptic AMPA receptor expression in cortical GABAergic interneurons and may play a role in conditions characterized by GABA-associated neuropathologic processes.
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28
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Lockhart M, Wirrig E, Phelps A, Wessels A. Extracellular matrix and heart development. ACTA ACUST UNITED AC 2011; 91:535-50. [PMID: 21618406 DOI: 10.1002/bdra.20810] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 02/04/2011] [Accepted: 02/21/2011] [Indexed: 12/23/2022]
Abstract
The extracellular matrix (ECM) of the developing heart contains numerous molecules that form a dynamic environment that plays an active and crucial role in the regulation of cellular events. ECM molecules found in the heart include hyaluronan, fibronectin, fibrillin, proteoglycans, and collagens. Tight regulation of the spatiotemporal expression, and the proteolytic processing of ECM components by proteases including members of the ADAMTS family, is essential for normal cardiac development. Perturbation of the expression of genes involved in matrix composition and remodeling can interfere with a myriad of events involved in the formation of the four-chambered heart and result in prenatal lethality or cardiac malformations as seen in humans with congenital heart disease. In this review, we summarize what is known about the specific importance of some of the components of the ECM in relation to the cardiovascular development.
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Affiliation(s)
- Marie Lockhart
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425, USA
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29
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Abstract
BACKGROUND Therapies targeting ERBB2 have shown success in the clinic. However, response is not determined solely by expression of ERBB2. Levels of ERBB3, its preferred heterodimerisation partner and ERBB ligands may also have a role. METHODS We measured NRG1 expression by real-time quantitative RT-PCR and ERBB receptors by western blotting and immunohistochemistry in bladder tumours and cell lines. RESULTS NRG1α and NRG1β showed significant coordinate expression. NRG1β was upregulated in 78% of cell lines. In tumours, there was a greater range of expression with a trend towards increased NRG1α with higher stage and grade. Increased expression of ERBB proteins was detected in 15% (EGFR), 20% (ERBB2), 41% (ERBB3) and 0% (ERBB4) of cell lines. High EGFR expression was detected in 28% of tumours, associated with grade and stage (P=0.05; P=0.04). Moderate or high expression of ERBB2 was detected in 22% and was associated with stage (P=0.025). Cytoplasmic ERBB3 was associated with high tumour grade (P=0.01) and with ERBB2 positivity. In cell lines, NRG1β expression was significantly inversely related to ERBB3, but this was not confirmed in tumours. CONCLUSION There is a wide spectrum of NRG1 and ERBB receptor expression in bladder cancer. In advanced tumours, EGFR, ERBB2 and ERBB3 upregulation is common and there is a relationship between expression of ERBB2 and ERBB3 but not the NRG1 ligand.
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Transient exposure of neonatal mice to neuregulin-1 results in hyperdopaminergic states in adulthood: implication in neurodevelopmental hypothesis for schizophrenia. Mol Psychiatry 2011; 16:307-20. [PMID: 20142818 DOI: 10.1038/mp.2010.10] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Neuregulin-1 (NRG1) is implicated in the etiology or pathology of schizophrenia, although its biological roles in this illness are not fully understood. Human midbrain dopaminergic neurons highly express NRG1 receptors (ErbB4). To test its neuropathological role in the neurodevelopmental hypothesis of schizophrenia, we administered type-1 NRG1 protein to neonatal mice and evaluated the immediate and subsequent effects on dopaminergic neurons and their associated behaviors. Peripheral NRG1 administration activated midbrain ErbB4 and elevated the expression, phosphorylation and enzyme activity of tyrosine hydroxylase (TH), which ultimately increased dopamine levels. The hyperdopaminergic state was sustained in the medial prefrontal cortex after puberty. There were marked increases in dopaminergic terminals and TH levels. In agreement, higher amounts of dopamine were released from this brain region of NRG1-treated mice following high potassium stimulation. Furthermore, NRG1-treated mice exhibited behavioral impairments in prepulse inhibition, latent inhibition, social behaviors and hypersensitivity to methamphetamine. However, there were no gross abnormalities in brain structures or other phenotypic features of neurons and glial cells. Collectively, our findings provide novel insights into neurotrophic contribution of NRG1 to dopaminergic maldevelopment and schizophrenia pathogenesis.
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31
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Yurchenco PD. Basement membranes: cell scaffoldings and signaling platforms. Cold Spring Harb Perspect Biol 2011; 3:cshperspect.a004911. [PMID: 21421915 DOI: 10.1101/cshperspect.a004911] [Citation(s) in RCA: 605] [Impact Index Per Article: 46.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Basement membranes are widely distributed extracellular matrices that coat the basal aspect of epithelial and endothelial cells and surround muscle, fat, and Schwann cells. These extracellular matrices, first expressed in early embryogenesis, are self-assembled on competent cell surfaces through binding interactions among laminins, type IV collagens, nidogens, and proteoglycans. They form stabilizing extensions of the plasma membrane that provide cell adhesion and that act as solid-phase agonists. Basement membranes play a role in tissue and organ morphogenesis and help maintain function in the adult. Mutations adversely affecting expression of the different structural components are associated with developmental arrest at different stages as well as postnatal diseases of muscle, nerve, brain, eye, skin, vasculature, and kidney.
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Affiliation(s)
- Peter D Yurchenco
- Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
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32
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Esper RM, Loeb JA. Neurotrophins induce neuregulin release through protein kinase Cdelta activation. J Biol Chem 2009; 284:26251-60. [PMID: 19648576 PMCID: PMC2785313 DOI: 10.1074/jbc.m109.002915] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 07/28/2009] [Indexed: 12/20/2022] Open
Abstract
Proper, graded communication between different cell types is essential for normal development and function. In the nervous system, heart, and for some cancer cells, part of this communication requires signaling by soluble and membrane-bound factors produced by the NRG1 gene. We have previously shown that glial-derived neurotrophic factors activate a rapid, localized release of soluble neuregulin from neuronal axons that can, in turn promote proper axoglial development (Esper, R. M., and Loeb, J. A. (2004) J. Neurosci. 24, 6218-6227). Here we elucidate the mechanism of this localized, regulated release by implicating the delta isoform of protein kinase C (PKC). Blocking the PKC delta isoform with either rottlerin, a selective antagonist, or small interference RNA blocks the regulated release of neuregulin from both transfected cells and primary neuronal cultures. PKC activation also leads to the rapid phosphorylation of the pro-NRG1 cytoplasmic tail on serine residues adjacent to the membrane-spanning segment, that, when mutated markedly reduce the rate of NRG1 activity release. These findings implicate this specific PKC isoform as an important factor for the cleavage and neurotrophin-regulated release of soluble NRG1 forms that have important effects in nervous system development and disease.
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Affiliation(s)
- Raymond M. Esper
- the Center for Molecular Medicine and Genetics, Wayne State University, Detroit, Michigan 48201
| | - Jeffrey A. Loeb
- From the Department of Neurology and
- the Center for Molecular Medicine and Genetics, Wayne State University, Detroit, Michigan 48201
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Ma Z, Li Q, An H, Pankonin MS, Wang J, Loeb JA. Targeting human epidermal growth factor receptor signaling with the neuregulin's heparin-binding domain. J Biol Chem 2009; 284:32108-15. [PMID: 19717564 DOI: 10.1074/jbc.m109.032714] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
A major limitation in biopharmaceutical development is selectively targeting drugs to diseased tissues. Growth factors and viruses have solved this problem by targeting tissue-specific cell-surface heparan sulfates. Neuregulin (NRG), a growth factor important in both nervous system development and cancer, has a unique heparin-binding domain (HBD) that targets to cell surfaces expressing its HER2/3/4 receptors (Esper, R. M., Pankonin, M. S., and Loeb, J. A. (2006) Brain Res. Rev. 51, 161-175). We have harnessed this natural targeting ability of NRG by fusing the HBD of NRG to soluble HER4. This fusion protein retains high affinity heparin binding to heparin and to cells that express heparan sulfates resulting in a more potent NRG antagonist. In vivo, it is targeted to peripheral nerve segments where it blocks the activity of NRG as a Schwann cell survival factor. The fusion protein also efficiently blocks autocrine and paracrine signaling and reduces the proliferation of MCF10CA1 breast cancer cells. These findings demonstrate the utility of the HBD of NRG in biopharmaceutical targeting and provide a new way to block HER signaling in cancer cells.
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Affiliation(s)
- Zhenzhong Ma
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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Pankonin MS, Sohi J, Kamholz J, Loeb JA. Differential distribution of neuregulin in human brain and spinal fluid. Brain Res 2008; 1258:1-11. [PMID: 19150438 DOI: 10.1016/j.brainres.2008.12.047] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 12/01/2008] [Accepted: 12/12/2008] [Indexed: 01/08/2023]
Abstract
The neuregulins are a family of polypeptide factors implicated in a wide range of neurological and psychiatric disorders including multiple sclerosis, schizophrenia, and Alzheimer's disease. Many alternatively-spliced forms of the NRG1 gene are released as soluble factors that can diffuse to near and distant sites within the nervous system where they can accumulate through binding to highly specific heparan-sulfate proteoglycans in the extracellular matrix. Here we have determined the sites of synthesis and accumulation of heparin-binding neuregulin forms in human neocortex, white matter, cerebral spinal fluid, and serum by immunostaining and measurement of neuregulin activity. While neuregulin precursors are expressed predominately within cortical neurons, soluble neuregulin accumulates preferentially on the surface of white matter astrocytes. Consistently, neuregulin activity can be released from the extracellular matrix of human brain by protease treatment. Neuregulin activity is also detectable in human cerebral spinal fluid where its expression appears to be altered in neuronal disorders. While cerebral spinal fluid neuregulin levels were unaltered in patients with multiple sclerosis, they were slightly reduced in amyotrophic lateral sclerosis and Parkinson's disease (p<0.15), but significantly increased in Alzheimer's disease (p<0.01). While not detected in human serum, a novel neuregulin antagonist activity was identified in human serum that could have prevented its detection. These results suggest that human neuregulin is selectively targeted from cortical neurons to white matter extracellular matrix where it exists in steady-state equilibrium with cerebral spinal fluid where it has the potential to serve as a biological marker in human neuronal disorders.
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Affiliation(s)
- Mark S Pankonin
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI 48201 , USA
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35
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Abstract
Increasing evidence indicates that many signaling pathways involve not only ligands and receptors but also various types of coreceptors and matrix components as additional layers of regulation. Signaling by Eph receptors and their ephrin ligands plays a key role in a variety of biological processes, such as axon guidance and topographic map formation, synaptic plasticity, angiogenesis, and cancer. Little is known about whether the ephrin-Eph receptor signaling system is subject to such additional layers of regulation. Here, we show that ephrin-A3 binds to heparan sulfate, and that the presence of cell surface heparan sulfate is required for the full biological activity of ephrin-A3. Among the ephrins tested, including ephrin-A1, -A2, -A5, -B1, and -B2, only ephrin-A3 binds heparin or heparan sulfate. Ephrin-A3-dependent EphA receptor activation is reduced in mutant cells that are defective in heparan sulfate synthesis, in wild-type cells from which cell surface heparan sulfate has been removed, and in the hippocampus of conditional knockout mice defective in heparan sulfate synthesis. Ephrin-A3-dependent cell rounding is impaired in CHO cells lacking heparan sulfate, and cortical neurons lacking heparan sulfate exhibit impaired growth cone collapse. In contrast, cell rounding and growth cone collapse in response to ephrin-A5, which does not bind heparan sulfate, are not affected by the absence of heparan sulfate. These results show that heparan sulfate modulates ephrin/Eph signaling and suggest a physiological role for heparan sulfate proteoglycans in the regulation of ephrin-A3-dependent biological processes.
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Zhang Z, Prentiss L, Heitzman D, Stahl RC, DiPino F, Carey DJ. Neuregulin isoforms in dorsal root ganglion neurons: effects of the cytoplasmic domain on localization and membrane shedding of Nrg-1 type I. J Neurosci Res 2006; 84:1-12. [PMID: 16615045 DOI: 10.1002/jnr.20861] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Embryonic sensory neurons express membrane-anchored growth factors that stimulate proliferation and differentiation of Schwann cells. The most important of these are members of the neuregulin-1 (Nrg-1) family that activate the erbB2/erbB3 receptor kinase on Schwann cells. Nrg-1 growth factors display a complex pattern of alternative mRNA splicing. We investigated the expression of the Nrg-1 type I in rat embryo dorsal root ganglion (DRG) neurons. Nrg-1 type I mRNA was abundantly expressed in DRG neurons; molecular cloning identified three distinct isoforms. The most prominent structural difference produced by alternative splicing was truncation of the C-terminal cytoplasmic domain. In sensory neurons and other cells, Nrg-1 type I proteins with the full-length 374-amino-acid cytoplasmic domain were expressed on the cell surface. In contrast, an isoform with a partially truncated cytoplasmic domain was retained in an intracellular compartment. Deletion studies demonstrated the presence of a cryptic intracellular retention signal that was exposed in the truncated cytoplasmic domain. Cell surface Nrg-1 type I molecules were subject to protease-dependent release of the biologically active ectodomain. As a consequence of their intracellular localization, the Nrg-1 type I isoform with a truncated cytoplasmic domain was not subject to membrane shedding. Nrg-1 type I ectodomain release was accelerated by factors present in Schwann cell-conditioned medium. In cells with active Nrg-1 type I ectodomain, shedding products corresponding to the cytoplasmic domain were not detected, because of rapid gamma-secretase- and proteasome-dependent degradation. These results demonstrate that sensory neurons express alternatively spliced neuregulin polypeptides with distinct subcellular localizations and processing.
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Affiliation(s)
- Zhiyou Zhang
- Weis Center for Research, Geisinger Clinic, Danville, Pennsylvania 17822-02601, USA
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37
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Hapner SJ, Nielsen KM, Chaverra M, Esper RM, Loeb JA, Lefcort F. NT-3 and CNTF exert dose-dependent, pleiotropic effects on cells in the immature dorsal root ganglion: Neuregulin-mediated proliferation of progenitor cells and neuronal differentiation. Dev Biol 2006; 297:182-97. [PMID: 16784738 DOI: 10.1016/j.ydbio.2006.05.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2005] [Revised: 05/01/2006] [Accepted: 05/10/2006] [Indexed: 01/19/2023]
Abstract
Neurons in the nascent dorsal root ganglia are born and differentiate in a complex cellular milieu composed of postmitotic neurons, and mitotically active glial and neural progenitor cells. Neurotrophic factors such as NT-3 are critically important for promoting the survival of postmitotic neurons in the DRG. However, the factors that regulate earlier events in the development of the DRG such as the mitogenesis of DRG progenitor cells and the differentiation of neurons are less defined. Here we demonstrate that both NT-3 and CNTF induce distinct dose-dependent responses on cells in the immature DRG: at low concentrations, they induce the proliferation of progenitor cells while at higher concentrations they promote neuronal differentiation. Furthermore, the mitogenic response is indirect; that is, NT-3 and CNTF first bind to nascent neurons in the DRG--which then stimulates those neurons to release mitogenic factors including neuregulin. Blockade of this endogenous neuregulin activity completely blocks the CNTF-induced proliferation and reduces about half of the NT-3-mediated proliferation. Thus, the genesis and differentiation of neurons and glia in the DRG are dependent upon reciprocal interactions among nascent neurons, glia, and mitotically active progenitor cells.
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Affiliation(s)
- Sharon J Hapner
- Department of Cell Biology and Neuroscience, Montana State University, Bozeman, MT 59717, USA
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38
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Cattaruzza S, Perris R. Approaching theProteoglycome: Molecular Interactions of Proteoglycans and Their Functional Output. Macromol Biosci 2006; 6:667-80. [PMID: 16881045 DOI: 10.1002/mabi.200600100] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
[Image: see text] Through their diverse core protein modules and glycan/glycosaminoglycan moieties, proteoglycans may engage in numerous cellular and molecular interactions which are dispensable during embryogenesis, are essential for the maintenance of a healthy state and are prone to modulation in pathological conditions. Proteoglycan interactions may involve binding to other structural components of the ECM, to cell surface receptors, to membrane-associated components, and to soluble signaling molecules, which through this interaction may become entrapped in the ECM or sequestered at the cell surface. Understanding of these multiple interplays is therefore of paramount importance and requires a detailed mapping through what we define as the proteoglycome.
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Affiliation(s)
- Sabrina Cattaruzza
- Department of Evolutionary and Functional Biology, University of Parma, Viale delle Scienze 11/A, Parma (PR) 43100, Italy
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Esper RM, Pankonin MS, Loeb JA. Neuregulins: Versatile growth and differentiation factors in nervous system development and human disease. ACTA ACUST UNITED AC 2006; 51:161-75. [PMID: 16412517 DOI: 10.1016/j.brainresrev.2005.11.006] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2005] [Revised: 11/02/2005] [Accepted: 11/04/2005] [Indexed: 12/29/2022]
Abstract
The neuregulins are a family of growth and differentiation factors with a wide range of functions in the nervous system. The power and diversity of the neuregulin signaling system comes in part from a large number of alternatively-spliced forms of the NRG1 gene that can produce both soluble and membrane-bound forms. The soluble forms of neuregulin are unique from other factors in that they have a structurally distinct heparin-binding domain that targets and potentiates its actions. In addition, a finely tuned, bidirectional mechanism regulates when and where neuregulin is released from neurons in response to neurotrophic factors produced by both neuronal targets and supporting glial cells. Together, this produces a balanced intercellular signaling system that can be localized to distinct regions for both normal development and maintenance of the mature nervous system. Recent evidence suggests that neuregulin signaling plays important roles in many neurological disorders including multiple sclerosis, traumatic brain and spinal cord injury, peripheral neuropathy, and schizophrenia. Here, we review the basic biology of neuregulins and relate this to research suggesting their involvement with and potential therapeutic uses for neurological disorders.
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Affiliation(s)
- Raymond M Esper
- Department of Neurology, Wayne State University, Detroit, MI 48201, USA
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40
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Harrison PJ, Law AJ. Neuregulin 1 and schizophrenia: genetics, gene expression, and neurobiology. Biol Psychiatry 2006; 60:132-40. [PMID: 16442083 DOI: 10.1016/j.biopsych.2005.11.002] [Citation(s) in RCA: 361] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2005] [Revised: 11/14/2005] [Accepted: 11/22/2005] [Indexed: 12/23/2022]
Abstract
Neuregulin 1 (NRG1) is a leading schizophrenia susceptibility gene. The NRG1 locus on chromosome 8p shows linkage to the disorder, and genetic association has been found between schizophrenia and various non-coding polymorphisms and haplotypes, especially at the 5' end of the NRG1 gene, in many but not all case-control and family studies. NRG1 is a pleiotropic growth factor, important in nervous system development and functioning; roles include the modulation of neuronal migration, synaptogenesis, gliogenesis, neuron-glia communication, myelination, and neurotransmission. Understanding the neurobiology of NRG1 and its involvement in schizophrenia is challenged by the complexity of the gene, which gives rise to multiple functionally distinct isoforms, including six "types" of NRG1 defined by 5' exon usage. Type IV and type I NRG1 may be particularly relevant to schizophrenia, with initial data showing altered expression of these isoforms in the disorder or in association with NRG1 risk alleles. We review the structure and functions of NRG1, consider the evidence for and against it being a schizophrenia susceptibility gene, and discuss mechanisms that might underlie the contribution of NRG1 to disease pathophysiology.
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Affiliation(s)
- Paul J Harrison
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, United Kingdom.
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41
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Warren CM, Kani K, Landgraf R. The N-terminal domains of neuregulin 1 confer signal attenuation. J Biol Chem 2006; 281:27306-16. [PMID: 16825199 DOI: 10.1074/jbc.m512887200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Degradation of activated ERBB receptors is an important mechanism for signal attenuation. However, compared with epidermal growth factor (EGF) receptor, the ERBB2/ERBB3 signaling pair is considered to be attenuation-deficient. The ERBB2/ERBB3 ligands of the neuregulin family rely on an EGF-like domain for signaling and are generated from larger membrane-bound precursors. In contrast to EGF, which is processed to yield a 6-kDa peptide ligand, mature neuregulins retain a variety of segments N-terminal to the EGF-like domain. Here we evaluate the role of the N-terminal domain of neuregulin 1 in signaling and turnover of ERBB2/ERBB3. Our data suggest that whereas the EGF-like domain of neuregulin 1 is required and sufficient for the formation of active receptor heterodimers, the presence of the N-terminal Ig-like domain is required for efficient signal attenuation. This manifests itself for both ERBB2 and ERBB3 but is more pronounced and coupled directly to degradation for ERBB3. When stimulated with only the EGF-like domain, ERBB3 shows degradation rates comparable with constitutive turnover, but stimulation with full-length neuregulin 1 resulted in receptor degradation at rates that are comparable with activated EGF receptor. Most of the enhancement in down-regulation was maintained after replacing the Ig-like domain with a thioredoxin protein of comparable size but different amino acid composition, suggesting that the physical presence but not specific properties of the Ig-like domain are needed. This sequence-independent effect of the N-terminal domain correlates with an enhanced ability of full-size neuregulin 1 to disrupt higher order oligomers of the ERBB3 extracellular domains in vitro.
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Affiliation(s)
- Carmen M Warren
- Department of Medicine, , Molecular Biology Institute, UCLA, Los Angeles, California 90095-1678, USA
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42
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Warren CM, Landgraf R. Signaling through ERBB receptors: Multiple layers of diversity and control. Cell Signal 2006; 18:923-33. [PMID: 16460914 DOI: 10.1016/j.cellsig.2005.12.007] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Accepted: 12/16/2005] [Indexed: 11/27/2022]
Abstract
The four known ERBB receptors in humans are involved in a broad range of cellular responses, and their deregulation is a significant aspect in a large number of disease states. However, their mechanism of action and modes of control are still poorly understood. This is largely due to the fact that the control of ERBB activity is a multilayered process with significant differences between the various ERBB members. In contrast to other receptor tyrosine kinases, the kinase domain of EGFR (ERBB1) does not require phosphorylation for activation. Consequently, the overall activation state of the receptor is controlled by constant balancing of activity favoring and activity suppressing actions within the receptor molecule. Influences of the membrane microenvironment and context dependent interactions with varying sets of signaling partners are superimposed on this system of intramolecular checks and balances. We will discuss current models of the control of ERBB signaling with an emphasis on the multilayered nature of activation control and aspects that give rise to diversity between ERBB receptors.
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Affiliation(s)
- Carmen M Warren
- University of California Los Angeles, Department of Medicine, Biological Chemistry, United States
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Cote GM, Miller TA, Lebrasseur NK, Kuramochi Y, Sawyer DB. Neuregulin-1alpha and beta isoform expression in cardiac microvascular endothelial cells and function in cardiac myocytes in vitro. Exp Cell Res 2005; 311:135-46. [PMID: 16185687 DOI: 10.1016/j.yexcr.2005.08.017] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2004] [Revised: 08/26/2005] [Accepted: 08/29/2005] [Indexed: 12/12/2022]
Abstract
Neuregulins (NRGs) are a family of alternatively spliced growth factors that act through receptor tyrosine kinases of the epidermal growth factor (EGF) receptor family in diverse tissues. The NRG-erbB signaling axis is a critical mediator of cardiac development, and growing evidence supports a role for this system in the intricate cross-talk between the microvascular endothelium and myocytes in the adult heart. The purpose of this study was first to examine the expression of splice variants of the NRG1 gene in adult rat cardiac microvascular endothelial cells and second to compare the function of these variants in cardiac myocytes. We demonstrate that cardiac microvascular endothelial cells in rat culture express multiple Type I NRG1 gene products, including both alpha and beta variants. Comparison of the activity of recombinant NRG1alpha and NRG1beta EGF-like domain proteins in cardiac myocytes shows that the beta ligand is a more potent activator of receptor phosphorylation and intracellular signaling than the alpha ligand, and only the beta ligand stimulated glucose uptake and protein synthesis in these culture conditions. Thus, cardiac microvascular endothelial cells express multiple NRG1 isotypes, but only beta-variants are biologically active on cardiac myocytes.
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Affiliation(s)
- Gregory M Cote
- Whitaker Cardiovascular Institute and Molecular Stress Response Unit, Cardiovascular Division, Department of Medicine, Boston University Medical Center, 650 Albany Street, Boston, X-320, MA 02118, USA
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Ding K, Lopez-Burks M, Sánchez-Duran JA, Korc M, Lander AD. Growth factor-induced shedding of syndecan-1 confers glypican-1 dependence on mitogenic responses of cancer cells. ACTA ACUST UNITED AC 2005; 171:729-38. [PMID: 16286510 PMCID: PMC2171561 DOI: 10.1083/jcb.200508010] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The cell surface heparan sulfate proteoglycan (HSPG) glypican-1 is up-regulated by pancreatic and breast cancer cells, and its removal renders such cells insensitive to many growth factors. We sought to explain why the cell surface HSPG syndecan-1, which is also up-regulated by these cells and is a known growth factor coreceptor, does not compensate for glypican-1 loss. We show that the initial responses of these cells to the growth factor FGF2 are not glypican dependent, but they become so over time as FGF2 induces shedding of syndecan-1. Manipulations that retain syndecan-1 on the cell surface make long-term FGF2 responses glypican independent, whereas those that trigger syndecan-1 shedding make initial FGF2 responses glypican dependent. We further show that syndecan-1 shedding is mediated by matrix metalloproteinase-7 (MMP7), which, being anchored to cells by HSPGs, also causes its own release in a complex with syndecan-1 ectodomains. These results support a specific role for shed syndecan-1 or MMP7-syndecan-1 complexes in tumor progression and add to accumulating evidence that syndecans and glypicans have nonequivalent functions in vivo.
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Affiliation(s)
- Kan Ding
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697
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Abstract
The human epidermal growth factor (EGF) receptor (HER) family of receptor tyrosine kinases has frequently been implicated in cancer. Apart from overexpression or mutation of these receptors, also the aberrant autocrine or paracrine activation of HERs by EGF-like ligands may be important in cancer progression. Neuregulins constitute a family of EGF-like ligands that bind to HER3 or HER4, preferably forming heterodimers with the orphan receptor HER2. Mesenchymal neuregulin typically serves as a pro-survival and pro-differentiation signal for adjacent epithelia. Disruption of the balance between proliferation and differentiation, because of autocrine production by the epithelial cells, increased sensitivity to paracrine signals or disruption of the spatial organization, may lead to constitutive receptor activation, in the absence of receptor overexpression. Consequently, the analysis of ligand expression and/or activated receptors in tumor samples may broaden the group of patients that can benefit from targeted therapies.
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Affiliation(s)
- Christophe Stove
- Laboratory of Experimental Cancerology, Department of Radiotherapy and Nuclear Medicine, Ghent University Hospital, Ghent, Belgium
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Donaldson T, Wang SH, Jacobsen TL, Schnepp B, Price J, Simcox A. Regulation of the Drosophila epidermal growth factor-ligand vein is mediated by multiple domains. Genetics 2005; 167:687-98. [PMID: 15238521 PMCID: PMC1470887 DOI: 10.1534/genetics.103.019588] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Vein (Vn), a ligand for the Drosophila epidermal growth factor receptor (Egfr), has a complex structure including a PEST, Ig, and EGF domain. We analyzed the structure-function relationships of Vn by assaying deletion mutants. The results show that each conserved domain influences Vn activity. A PEST deletion increases Vn potency and genetic evidence suggests that Vn is regulated by proteasomal degradation. The Ig deletion causes toxic effects not seen following expression of native Vn, but the Ig domain is not required for Vn localization or for the activation of Egfr signaling in wing vein patterning. Remarkably, when the EGF domain is deleted, Vn functions as a dominant negative ligand, implying that Vn normally physically interacts with another factor to promote its activity. We identified additional highly conserved sequences and found several regions that affect Vn potency and one that may mediate the effect of dominant negative Vn molecules. Together the results show that the activity of Vn is controlled both positively and negatively, demonstrating the existence of additional levels at which Egfr signaling can be regulated.
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Affiliation(s)
- Timothy Donaldson
- Department of Molecular Genetics, Ohio State University, Columbus, 43210, USA
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Abstract
During peripheral nervous system development, Schwann cells are precisely matched to the axons that they support. This is mediated by axonal neuregulins that are essential for Schwann cell survival and differentiation. Here, we show that sensory and motor axons rapidly release heparin-binding forms of neuregulin in response to Schwann cell-derived neurotrophic factors in a dose-dependent manner. Neuregulin release occurs within minutes, is saturable, and occurs from axons that were isolated using a newly designed chamber slide apparatus. Although NGF and glial cell line-derived neurotrophic factor (GDNF) were the most potent neurotrophic factors to release neuregulin from sensory neurons, GDNF and BDNF were most potent for motor neurons and were the predominant neuregulin-releasing neurotrophic factors produced by cultured Schwann cells. Comparable levels of neuregulin could be released at a similar rate from neurons after protein kinase C activation with the phorbol ester, phorbol 12-myristate 13-acetate, which has also been shown to promote the cleavage and release of neuregulin from its transmembrane precursor. The rapid release of neuregulin from axons in response to Schwann cell-derived neurotrophic factors may be part of a spatially restricted system of communication at the axoglial interface important for proper peripheral nerve development, function, and repair.
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MESH Headings
- Animals
- Axons/drug effects
- Axons/physiology
- Cells, Cultured
- Chick Embryo
- Culture Media, Conditioned/pharmacology
- Diffusion Chambers, Culture
- Dose-Response Relationship, Drug
- Ganglia, Spinal/cytology
- Ganglia, Spinal/embryology
- Heparin/metabolism
- Motor Neurons/cytology
- Motor Neurons/drug effects
- Motor Neurons/metabolism
- Nerve Growth Factors/biosynthesis
- Nerve Growth Factors/genetics
- Nerve Growth Factors/pharmacology
- Neuregulin-1/metabolism
- Neuregulin-1/pharmacology
- Neurons, Afferent/cytology
- Neurons, Afferent/drug effects
- Neurons, Afferent/metabolism
- RNA, Messenger/biosynthesis
- Rats
- Schwann Cells/cytology
- Schwann Cells/drug effects
- Schwann Cells/metabolism
- Sciatic Nerve/metabolism
- Signal Transduction/drug effects
- Signal Transduction/physiology
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Affiliation(s)
- Raymond M Esper
- Department of Neurology, Wayne State University, Detroit, Michigan 48201, USA
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Li Q, Ahmed S, Loeb JA. Development of an autocrine neuregulin signaling loop with malignant transformation of human breast epithelial cells. Cancer Res 2004; 64:7078-85. [PMID: 15466203 DOI: 10.1158/0008-5472.can-04-1152] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Neuregulin (NRG) is a heparin-binding factor that activates members of the epidermal growth factor family of tyrosine kinase receptors including erbB2 that is overexpressed in more aggressive types of breast cancer. The exact role that NRG plays in breast cancer is complicated by the fact that NRG has been shown to have both proliferative and antiproliferative effects, depending on the breast cancer cell line used. Using an isogenic series of breast epithelial cell lines (MCF10A) ranging from benign to malignant, we found that the actions of NRG changed from antiproliferative to proliferative as the cells progress to cancer. This correlated with a progressive inability of NRG to down-regulate a group of proliferation genes identified previously using cDNA microarrays. As the cells progress to malignancy, they expressed higher levels of erbB2 and lower levels of erbB3 and secreted high levels of NRG into the culture media, resulting in high basal levels of erbB receptor phosphorylation. Disruption of this autocrine signaling loop by blocking ligand-induced receptor activation inhibited cancer cell proliferation. These results demonstrate that the transition of MCF10A cells from normal to premalignant to malignant correlates with the development of a constitutively active autocrine NRG signaling loop that promotes cell proliferation and suggest that disrupting this autocrine loop may provide an important therapeutic measure to control breast cancer cell growth.
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Affiliation(s)
- Qunfang Li
- Department of Neurology and Center for Molecular Medicine and Genetics, Wayne State University, Detroit, Michigan 48201, USA
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Pankonin MS, Gallagher JT, Loeb JA. Specific structural features of heparan sulfate proteoglycans potentiate neuregulin-1 signaling. J Biol Chem 2004; 280:383-8. [PMID: 15528194 DOI: 10.1074/jbc.m402645200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Neuregulins are a family of growth and differentiation factors that act through activation of cell-surface erbB receptor tyrosine kinases and have essential functions both during development and on the growth of cancer cells. One alternatively spliced neuregulin-1 form has a distinct heparin-binding immunoglobulin-like domain that enables it to adhere to heparan sulfate proteoglycans at key locations during development and substantially potentiates its activity. We examined the structural specificity needed for neuregulin-1-heparin interactions using a gel mobility shift assay together with an assay that measures the ability of specific oligosaccharides to block erbB receptor phosphorylation in L6 muscle cells. Whereas the N-sulfate group of heparin was most important, the 2-O-sulfate and 6-O-sulfate groups also contributed to neuregulin-1 binding in these two assays. Optimal binding to neuregulin-1 required eight or more heparin disaccharides; however, as few as two disaccharides were still able to bind neuregulin-1 to a lesser extent. The physiological importance of this specificity was shown both by chemical and siRNA treatment of cultured muscle cells. Pretreatment of muscle cells with chlorate that blocks all sulfation or with an siRNA that selectively blocks N-sulfation significantly reduced erbB receptor activation by neuregulin-1 but had no effect on the activity of neuregulin-1 that lacks the heparin-binding domain. These results suggest that the regulation of glycosaminoglycan sulfation is an important biological mechanism that can modulate both the localization and potentiation of neuregulin-1 signaling.
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Affiliation(s)
- Mark S Pankonin
- Department of Neurology, Wayne State University, Detroit, Michigan 48201, USA
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50
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Li Q, Esper RM, Loeb JA. Synergistic effects of neuregulin and agrin on muscle acetylcholine receptor expression. Mol Cell Neurosci 2004; 26:558-69. [PMID: 15276157 DOI: 10.1016/j.mcn.2004.04.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2004] [Revised: 04/19/2004] [Accepted: 04/27/2004] [Indexed: 11/24/2022] Open
Abstract
The proper function of neuromuscular junctions requires an extremely high density of acetylcholine receptors (AChRs) that may be achieved from neuron-derived factors including agrin and neuregulin. Here, we show that neuregulin-1 and agrin co-localize at neuromuscular junctions in vivo and form complexes when co-transfected into COS-7 cells. When these COS-7 cells are cultured with myotubes, synergistic effects are observed for AChR clustering, membrane insertion of new AChRs, and induction of AChR mRNA. Even a muscle form of agrin that lacks intrinsic clustering activities by itself, significantly enhances neuregulin-induced clustering and insertion of AChRs. While the heparin-binding (A) domain of agrin is required for agrin localization in the extracellular matrix adjacent to AChR clusters, the heparan sulfate-containing domain of agrin is needed for the synergistic effects and co-localization with neuregulin-1. These results suggest that matrix interactions between exogenously supplied agrin and neuregulin-1 on the muscle surface provide a localized source of signaling factors needed to produce high densities of AChRs at neuromuscular junctions.
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MESH Headings
- Agrin/genetics
- Agrin/metabolism
- Agrin/pharmacology
- Animals
- Avian Proteins
- Binding Sites/genetics
- COS Cells
- Cell Membrane/drug effects
- Cell Membrane/genetics
- Cell Membrane/metabolism
- Chick Embryo
- Coculture Techniques
- Extracellular Matrix/drug effects
- Extracellular Matrix/genetics
- Extracellular Matrix/metabolism
- Gene Expression Regulation, Developmental/drug effects
- Gene Expression Regulation, Developmental/genetics
- Heparin/metabolism
- Heparitin Sulfate/metabolism
- Muscle Fibers, Skeletal/cytology
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Muscle, Skeletal/embryology
- Muscle, Skeletal/innervation
- Muscle, Skeletal/metabolism
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Nerve Tissue Proteins/pharmacology
- Neuregulin-1
- Neuromuscular Junction/embryology
- Neuromuscular Junction/genetics
- Neuromuscular Junction/metabolism
- Protein Binding/drug effects
- Protein Binding/genetics
- Protein Structure, Tertiary/genetics
- RNA, Messenger/drug effects
- RNA, Messenger/metabolism
- Receptor Aggregation/drug effects
- Receptor Aggregation/genetics
- Receptors, Nicotinic/genetics
- Receptors, Nicotinic/metabolism
- Transfection
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Affiliation(s)
- Qunfang Li
- Department of Neurology and The Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA
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