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Abstract
Neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD) and amyotrophic lateral sclerosis (ALS), are typically characterized by progressive neuronal loss and neurological dysfunctions in the nervous system, affecting both memory and motor functions. Neuregulins (NRGs) belong to the epidermal growth factor (EGF)-like family of extracellular ligands and they play an important role in the development, maintenance, and repair of both the central nervous system (CNS) and peripheral nervous system (PNS) through the ErbB signaling pathway. They also regulate multiple intercellular signal transduction and participate in a wide range of biological processes, such as differentiation, migration, and myelination. In this review article, we summarized research on the changes and roles of NRGs in neurodegenerative diseases, especially in AD. We elaborated on the structural features of each NRG subtype and roles of NRG/ErbB signaling networks in neurodegenerative diseases. We also discussed the therapeutic potential of NRGs in the symptom remission of neurodegenerative diseases, which may offer hope for advancing related treatment.
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Affiliation(s)
- Guan-yong Ou
- Center for Neuroscience, Shantou University Medical College, Shantou, China
| | - Wen-wen Lin
- Center for Neuroscience, Shantou University Medical College, Shantou, China
| | - Wei-jiang Zhao
- Center for Neuroscience, Shantou University Medical College, Shantou, China
- Cell Biology Department, Wuxi School of Medicine, Jiangnan University, Wuxi, China
- *Correspondence: Wei-jiang Zhao
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2
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Parodi EM, Kuhn B. Signalling between microvascular endothelium and cardiomyocytes through neuregulin. Cardiovasc Res 2014; 102:194-204. [PMID: 24477642 PMCID: PMC3989448 DOI: 10.1093/cvr/cvu021] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 12/23/2013] [Accepted: 01/10/2014] [Indexed: 12/26/2022] Open
Abstract
Heterocellular communication in the heart is an important mechanism for matching circulatory demands with cardiac structure and function, and neuregulins (Nrgs) play an important role in transducing this signal between the hearts' vasculature and musculature. Here, we review the current knowledge regarding Nrgs, explaining their roles in transducing signals between the heart's microvasculature and cardiomyocytes. We highlight intriguing areas being investigated for developing new, Nrg-mediated strategies to heal the heart in acquired and congenital heart diseases, and note avenues for future research.
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Affiliation(s)
| | - Bernhard Kuhn
- Harvard Medical School, Boston Children's Hospital, 300 Longwood Avenue, Enders Building, Room 1212, Brookline, MA 02115, USA
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Hayes NVL, Gullick WJ. The neuregulin family of genes and their multiple splice variants in breast cancer. J Mammary Gland Biol Neoplasia 2008; 13:205-14. [PMID: 18415007 DOI: 10.1007/s10911-008-9078-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2008] [Accepted: 03/17/2008] [Indexed: 01/28/2023] Open
Abstract
The neuregulin family consists of four genes, NRG1-4 which can each encode products containing a domain related to the epidermal growth factor family of ligands. Each gene is subject to complex control of transcription and to splicing of their mRNA product to give many variant proteins. These do not contain secretory sequences but some, through their transmembrane sequence, are routed via the Golgi where they are glycosylated, to the cell surface. Here they may be released by regulated proteolysis to act as soluble proteins which can interact and activate members of the EGF receptor family of receptor tyrosine kinases. Other splice variants do not encode transmembrane sequences and these are found either in the cytoplasm or, if they encode a nuclear localisation sequence, in distinct compartments in the nucleoplasm. It has been shown that the variants containing a full EGF domain can act as receptor agonists but the function of the cytoplasmic and nuclear products is unknown as yet. All four neuregulin genes are expressed and play an important role in mammary gland development. They are also expressed at elevated levels in some cases of ductal carcinoma in situ of the breast and breast cancer. They seem to be active in this setting and their presence may affect the efficacy of treatment with endocrine agents or with signal transduction inhibitors directed at the EGF receptor family members. Much remains to be learned however of their normal function and their influence on breast cancer development, progression and response to therapy.
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Affiliation(s)
- Nandini V L Hayes
- Department of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK
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4
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Hayes NVL, Blackburn E, Smart LV, Boyle MM, Russell GA, Frost TM, Morgan BJT, Baines AJ, Gullick WJ. Identification and characterization of novel spliced variants of neuregulin 4 in prostate cancer. Clin Cancer Res 2007; 13:3147-55. [PMID: 17545517 DOI: 10.1158/1078-0432.ccr-06-2237] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE The neuregulin (NRG) 1, 2, and 3 genes undergo extensive alternative mRNA splicing, which results in variants that show structural and functional diversity. The aims of this study were to establish whether the fourth member of this family, NRG4, is expressed in prostate cancer, if it is alternatively spliced and whether any functional differences between the variants could be observed. EXPERIMENTAL DESIGN The expression of NRG4 was determined using immunohistochemical staining of 40 cases of primary prostate cancer. Bioinformatic analysis and reverse transcription-PCR (RT-PCR) using NRG4 isotype-specific primers on a panel of normal and prostate cancer cell lines were used to identify alternatively spliced NRG4 variants. Expression of these variants was determined using isotype-specific antibodies. Transfection into Cos-7 cells of two of these green fluorescent protein-tagged variants allowed analysis of their subcellular location. Four of the variants were chemically synthesized and tested for their ability to activate the ErbB4 receptor. RESULTS NRG4 was variably expressed in the cytoplasm in the majority of prostate cancer cases, and in a subset of cases in the membrane, high levels were associated with advanced disease stage. Four novel NRG4 splice variants (NRGA2, NRG4 B1-3) were characterized, where each seemed to have a different subcellular location and were also expressed in the cytoplasm of the prostate tumors. NRG4 B3 was also present in endothelial cells. In transfected cells, the A type variant (NRG4 A1) was localized to the membrane, whereas the B type variant (NRG4 B1), which lacks the predicted transmembrane region, had an intracellular localization. Only the variants with an intact epidermal growth factor-like domain activated ErbB4 signaling. CONCLUSION NRG4 overexpression is associated with advanced-stage prostate cancer. The alternative splice variants may have different roles in cell signaling, some acting as classic receptor ligands and some with as-yet unknown functions.
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Affiliation(s)
- Nandini V L Hayes
- Cancer Biology Laboratory, Research School of Biosciences, Centre for Biomedical Informatics, Institute of Mathematics and Statistics, University of Kent, Canterbury, UK.
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5
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Abstract
The NRG4 gene is a member of a family of four genes that encode a class of epidermal growth factors. This gene has been reported to express a protein designated here as NRG4A1. We describe here a novel splice variant of the NRG4 gene, NRG4A2, which encodes a C-terminal region containing a predicted type I PDZ-binding peptide. Both NRG4A1 and NRG4A2 were shown to be expressed on the cell surface, as expected by the presence of a predicted transmembrane sequence, and were modified at a single N-linked glycosylation site in the extracellular domain. Significant stabilization of expression of both proteins was seen in the presence of the proteosome inhibitor MG-132 suggesting that they are normally degraded by this system. N-terminal cleavage was inhibited in both isotypes by the broad-spectrum matrix metalloproteinase inhibitor, galardin (GM 6001). A glycosylated, secreted form of NRG4A1 was detected in the cell medium which showed biological activity in two assays, phosphorylation of the HER4 receptor and stimulation of neurite formation in PC-12 cells stably expressing HER4. Transfection and expression of green fluorescent protein-tagged proteins and immunofluorescent staining with specific anti-peptide antibodies showed that NRG4A1 is localized to membrane ruffles, while NRG4A2 has a more punctate membrane distribution.
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Affiliation(s)
- N V L Hayes
- Cancer Biology Laboratory, Research School of Biosciences, University of Kent, Canterbury, UK
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Ponomareva ON, Ma H, Dakour R, Raabe TD, Lai C, Rimer M. Stimulation of acetylcholine receptor transcription by neuregulin-2 requires an N-box response element and is regulated by alternative splicing. Neuroscience 2005; 134:495-503. [PMID: 15961242 DOI: 10.1016/j.neuroscience.2005.04.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2005] [Accepted: 04/18/2005] [Indexed: 11/23/2022]
Abstract
The neuregulin (Nrg) family of growth/differentiation factors is encoded by at least four genes in the mammalian genome: nrg-1, nrg-2, nrg-3 and nrg-4. Nrg-1 and Nrg-2 share the highest homology within the family, and the primary RNA transcripts from their encoding genes are subjected to extensive alternative splicing. Although little is known about the biological function of Nrg-2-4, their structural similarity with Nrg-1 suggests that they could account for some of the activities presently attributed to Nrg-1. Thus, at the neuromuscular junction Nrg-1 has been a favored candidate for the signal that activates selective acetylcholine receptor (AChR) transcription in synaptic myonuclei. However, we have recently shown that like Nrg-1, Nrg-2 can also activate AChR transcription in cultured myotubes and accumulates at the synaptic site. Synapse-specific and Nrg-1-induced AChR transcription require an enhancer sequence, the N-box, which is also mutated in some patients with congenital myasthenia gravis. Here, we show that Nrg-2-induced AChR transcription requires an N-box motif and is regulated by alternative splicing. We also show that unique Nrg-2 isoforms are differentially distributed between spinal cord and skeletal muscle, the tissues that harbor the cellular components of the neuromuscular synapse.
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Affiliation(s)
- O N Ponomareva
- Section of Neurobiology, University of Texas at Austin, Austin, TX 78712, USA
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7
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Marshall C, Blackburn E, Clark M, Humphreys S, Gullick WJ. Neuregulins 1-4 are expressed in the cytoplasm or nuclei of ductal carcinoma (in situ) of the human breast. Breast Cancer Res Treat 2005; 96:163-8. [PMID: 16261396 DOI: 10.1007/s10549-005-9073-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2005] [Accepted: 09/06/2005] [Indexed: 10/25/2022]
Abstract
A new family of epidermal growth factor-like proteins, the Neuregulins (NRGs), have recently been identified and are expressed in a range of normal tissues and in some forms of cancer including breast cancer. In this study we examined using immunohistochemical staining expression of NRG1alpha, NRG1beta, NRG2alpha, NRG2beta, NRG3 and NRG4 in sixty cases of pre-invasive ductal carcinoma in situ of the breast representing different degrees of differentiation. Each protein was expressed in a high proportion of these cases showing a predominantly homogenous cytoplasmic staining pattern. Nuclear expression of NRG1alpha, NRG1beta, and NRG3 was however also observed in a significant fraction of cases. High levels of expression of NRG2beta and NRG4 were associated with high-grade tumours (p< or =0.005), NRG2beta staining was associated with tumour size >25 mm (p=0.005) while NRG3 nuclear staining was present more often in low-grade tumours (p=0.039). This data demonstrates that each member of the NRG family of ligands is present in pre-invasive ductal breast cancer and that they may be involved in regulating cell behaviour. The significance of intranuclear expression remains to be determined but suggests a novel mechanism of action for some of these proteins.
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Abstract
The neuregulins (NRGs) are a family of four structurally related growth factors that are expressed in the developing and adult brain. NRG-1 is essential for normal heart formation and has been implicated in the development and maintenance of both neurons and glia. NRG-2 was identified on the basis of its homology to NRG-1 and, like NRG-1, is expressed predominantly by neurons in the central nervous system. We have generated mice with the active domain of NRG-2 deleted in an effort to characterize the biological function of NRG-2 in vivo. In contrast to the NRG-1 knockout animals, NRG-2 knockouts have no apparent heart defects and survive embryogenesis. Mutant mice display early growth retardation and reduced reproductive capacity. No obvious histological differences were observed in the major sites of NRG-2 expression. Our results indicate that in vivo NRG-2 activity differs substantially from that of NRG-1 and that it is not essential for normal development in utero.
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Affiliation(s)
- Joanne M Britto
- Western Australian Institute for Medical Research and UWA Centre for Medical Research, University of Western Australia, Perth, Australia
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9
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Affiliation(s)
- D A Talmage
- Institute for Human Nutrition and Department of Pediatrics, Columbia University, New York, New York 10032, USA
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10
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Rimer M, Prieto AL, Weber JL, Colasante C, Ponomareva O, Fromm L, Schwab MH, Lai C, Burden SJ. Neuregulin-2 is synthesized by motor neurons and terminal Schwann cells and activates acetylcholine receptor transcription in muscle cells expressing ErbB4. Mol Cell Neurosci 2004; 26:271-81. [PMID: 15207852 DOI: 10.1016/j.mcn.2004.02.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2003] [Revised: 01/29/2004] [Accepted: 02/11/2004] [Indexed: 12/24/2022] Open
Abstract
Acetylcholine receptor (AChR) genes are transcribed selectively in synaptic nuclei of skeletal muscle fibers, leading to accumulation of the mRNAs encoding AChR subunits at synaptic sites. The signals that regulate synapse-specific transcription remain elusive, though Neuregulin-1 is considered a favored candidate. Here, we show that motor neurons and terminal Schwann cells express neuregulin-2, a neuregulin-1-related gene. In skeletal muscle, Neuregulin-2 protein is concentrated at synaptic sites, where it accumulates adjacent to terminal Schwann cells. Neuregulin-2 stimulates AChR transcription in cultured myotubes expressing ErbB4, as well as ErbB3 and ErbB2, but not in myotubes expressing only ErbB3 and ErbB2. Thus, Neuregulin-2 is a candidate for a signal that regulates synaptic differentiation.
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MESH Headings
- Animals
- Cell Differentiation/genetics
- Cells, Cultured
- Choline O-Acetyltransferase/metabolism
- ErbB Receptors/genetics
- ErbB Receptors/metabolism
- Gene Expression Regulation, Developmental/genetics
- Glycoproteins/genetics
- Glycoproteins/metabolism
- Motor Neurons/cytology
- Motor Neurons/metabolism
- Muscle Fibers, Skeletal/cytology
- Muscle Fibers, Skeletal/metabolism
- Muscle, Skeletal/cytology
- Muscle, Skeletal/innervation
- Muscle, Skeletal/metabolism
- Nerve Growth Factors/genetics
- Nerve Growth Factors/metabolism
- Neuromuscular Junction/cytology
- Neuromuscular Junction/metabolism
- Phosphorylation
- Rats
- Rats, Sprague-Dawley
- Rats, Wistar
- Receptor, ErbB-2
- Receptor, ErbB-3/genetics
- Receptor, ErbB-3/metabolism
- Receptor, ErbB-4
- Receptors, Cholinergic/genetics
- Receptors, Cholinergic/metabolism
- Schwann Cells/cytology
- Schwann Cells/metabolism
- Synaptic Membranes/genetics
- Synaptic Membranes/metabolism
- Transcriptional Activation/genetics
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Affiliation(s)
- Mendell Rimer
- Molecular Neurobiology Program, Skirball Institute of Biomolecular Medicine, NYU Medical School, New York, NY 10016, USA.
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Nakano N, Higashiyama S, Ohmoto H, Ishiguro H, Taniguchi N, Wada Y. The N-terminal region of NTAK/neuregulin-2 isoforms has an inhibitory activity on angiogenesis. J Biol Chem 2004; 279:11465-70. [PMID: 14722120 DOI: 10.1074/jbc.m311045200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
NTAK (neural- and thymus-derived activator for ErbB kinases), also known as neuregulin-2, is a member of the epidermal growth factor (EGF) family, which binds directly to ErbB3 and ErbB4 and transactivates ErbB2. Because ErbB signaling has been implicated in various angiogenic mechanisms, the effect of NTAK (which has at least nine isoforms due to alternative splicing) in angiogenesis is explored. One isoform, NTAKgamma, inhibited cell growth in terms of DNA synthesis and cell numbers in vascular endothelial cells specifically, whereas NTAKalpha and beta had no activity. On the other hand, NTAKgamma secreted by transfected MDA-MB-231 cells inhibited endothelial cell growth, and NTAKgamma expressed in endothelial cells by adenovirus infection suppressed cell growth in a dose-dependent manner. The EGF-like domain of NTAKgamma did not have this activity. The NTAKdelta isoform, which had the Ig-like domain but not the EGF-like domain, inhibited proliferation of endothelial cells. NTAKdelta prevented hyper-phosphorylation of the retinoblastoma tumor suppressor protein and caused G(1) arrest in endothelial cells. Both NTAKgamma and delta isoforms displayed anti-angiogenic activity in the chick embryo chorioallantoic membrane in vivo. These results suggest that the active site of NTAK is localized outside of the EGF-like domain but within the N-terminal region, including the Ig-like domain, of NTAK.
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Affiliation(s)
- Norihiko Nakano
- Department of Molecular Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, 840 Murodo-cho, Izumi, Osaka 594-1101, Japan.
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12
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Abstract
Neuregulin-1 (NRG-1) regulates numerous aspects of neural development and synaptic plasticity; the functions of NRG-2 and NRG-3 are presently unknown. As a first step toward understanding how NRGs contribute to distinct aspects of neural development and function, we characterized their regional and subcellular expression patterns in developing brain. The expression of NRG-1-3 mRNAs was compared postnatally (P0, P7, adult) by using in situ hybridization. NRG-1 expression is highest at birth, whereas NRG-2 mRNA levels increase with development; expression of both genes is restricted to distinct brain regions. In contrast, NRG-3 transcripts are abundant in most brain regions throughout development. NRG-2 antibodies were generated to analyze protein processing, expression, and subcellular distribution. As with NRG-1, the transmembrane NRG-2 proprotein is proteolytically processed in transfected HEK 293 cells and in neural tissues, and its ectodomain is exposed and accumulates on the neuron surface. Despite the structural similarities between NRG-1 and NRG-2, we unexpectedly found that NRG-2 colocalizes with MAP2 in proximal primary dendrites of hippocampal neurons in culture and in vivo, although it is not detectable in axons or in axon terminals. These findings were confirmed with NRG-2 ectodomain antisera and epitope-tagged recombinant protein. In cerebellum, NRG-2 colocalizes with calbindin in proximal dendrites and soma of Purkinje cells. In contrast, NRG-1 is highly expressed in axons of dissociated hippocampal neurons, as well as in somas and dendrites. The distinct temporal, regional, and subcellular expression of NRG-2 suggests its unique and nonredundant role in neural function.
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Affiliation(s)
- Marines Longart
- Section on Molecular Neurobiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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