1
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Mitok KA, Keller MP, Attie AD. Sorting through the extensive and confusing roles of sortilin in metabolic disease. J Lipid Res 2022; 63:100243. [PMID: 35724703 PMCID: PMC9356209 DOI: 10.1016/j.jlr.2022.100243] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 06/10/2022] [Accepted: 06/13/2022] [Indexed: 01/06/2023] Open
Abstract
Sortilin is a post-Golgi trafficking receptor homologous to the yeast vacuolar protein sorting receptor 10 (VPS10). The VPS10 motif on sortilin is a 10-bladed β-propeller structure capable of binding more than 50 proteins, covering a wide range of biological functions including lipid and lipoprotein metabolism, neuronal growth and death, inflammation, and lysosomal degradation. Sortilin has a complex cellular trafficking itinerary, where it functions as a receptor in the trans-Golgi network, endosomes, secretory vesicles, multivesicular bodies, and at the cell surface. In addition, sortilin is associated with hypercholesterolemia, Alzheimer's disease, prion diseases, Parkinson's disease, and inflammation syndromes. The 1p13.3 locus containing SORT1, the gene encoding sortilin, carries the strongest association with LDL-C of all loci in human genome-wide association studies. However, the mechanism by which sortilin influences LDL-C is unclear. Here, we review the role sortilin plays in cardiovascular and metabolic diseases and describe in detail the large and often contradictory literature on the role of sortilin in the regulation of LDL-C levels.
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Affiliation(s)
- Kelly A Mitok
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Mark P Keller
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Alan D Attie
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA.
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2
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Dedoni S, Marras L, Olianas MC, Ingianni A, Onali P. Valproic acid upregulates the expression of the p75NTR/sortilin receptor complex to induce neuronal apoptosis. Apoptosis 2021; 25:697-714. [PMID: 32712736 PMCID: PMC7527367 DOI: 10.1007/s10495-020-01626-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The antiepileptic and mood stabilizer agent valproic acid (VPA) has been shown to exert anti-tumour effects and to cause neuronal damage in the developing brain through mechanisms not completely understood. In the present study we show that prolonged exposure of SH-SY5Y and LAN-1 human neuroblastoma cells to clinically relevant concentrations of VPA caused a marked induction of the protein and transcript levels of the common neurotrophin receptor p75NTR and its co-receptor sortilin, two promoters of apoptotic cell death in response to proneurotrophins. VPA induction of p75NTR and sortilin was associated with an increase in plasma membrane expression of the receptor proteins and was mimicked by cell treatment with several histone deacetylase (HDAC) inhibitors. VPA and HDAC1 knockdown decreased the level of EZH2, a core component of the polycomb repressive complex 2, and upregulated the transcription factor CASZ1, a positive regulator of p75NTR. CASZ1 knockdown attenuated VPA-induced p75NTR overexpression. Cell treatment with VPA favoured proNGF-induced p75NTR/sortilin interaction and the exposure to proNGF enhanced JNK activation and apoptotic cell death elicited by VPA. Depletion of p75NTR or addition of the sortilin agonist neurotensin to block proNGF/sortilin interaction reduced the apoptotic response to VPA and proNGF. Exposure of mouse cerebellar granule cells to VPA upregulated p75NTR and sortilin and induced apoptosis which was enhanced by proNGF. These results indicate that VPA upregulates p75NTR apoptotic cell signalling through an epigenetic mechanism involving HDAC inhibition and suggest that this effect may contribute to the anti-neuroblastoma and neurotoxic effects of VPA.
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Affiliation(s)
- Simona Dedoni
- Laboratory of Cellular and Molecular Pharmacology, Section of Neurosciences and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari, 09042, Monserrato, CA, Italy
| | - Luisa Marras
- Section of Microbiology, Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy
| | - Maria C Olianas
- Laboratory of Cellular and Molecular Pharmacology, Section of Neurosciences and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari, 09042, Monserrato, CA, Italy
| | - Angela Ingianni
- Section of Microbiology, Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy
| | - Pierluigi Onali
- Laboratory of Cellular and Molecular Pharmacology, Section of Neurosciences and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari, 09042, Monserrato, CA, Italy.
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3
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Schwarz E. Cystine knot growth factors and their functionally versatile proregions. Biol Chem 2017; 398:1295-1308. [PMID: 28771427 DOI: 10.1515/hsz-2017-0163] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 07/16/2017] [Indexed: 12/23/2022]
Abstract
The cystine knot disulfide pattern has been found to be widespread in nature, since it has been detected in proteins from plants, marine snails, spiders and mammals. Cystine knot proteins are secreted proteins. Their functions range from defense mechanisms as toxins, e.g. ion channel or enzyme inhibitors, to hormones, blood factors and growth factors. Cystine knot proteins can be divided into two superordinate groups. (i) The cystine knot peptides, also referred to - with other non-cystine knot proteins - as knottins, with linear and cyclic polypeptide chains. (ii) The cystine knot growth factor family, which is in the focus of this article. The disulfide ring structure of the cystine knot peptides is made up by the half-cystines 1-4 and 2-5, and the threading disulfide bond is formed by the half-cystines, 3-6. In the growth factor group, the disulfides of half-cystines 1 and 4 pass the ring structure formed by the half-cystines 2-5 and 3-6. In this review, special emphasis will be devoted to the growth factor cystine knot proteins and their proregions. The latter have shifted into the focus of scientific interest as their important biological roles are just to be unravelled.
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4
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Garcia TB, Hollborn M, Bringmann A. Expression and signaling of NGF in the healthy and injured retina. Cytokine Growth Factor Rev 2017; 34:43-57. [PMID: 27964967 DOI: 10.1016/j.cytogfr.2016.11.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 11/28/2016] [Indexed: 01/02/2023]
Abstract
This review summarizes the present knowledge concerning the retinal localization of the nerve growth factor (NGF), its precursor proNGF, and the receptors TrkA and p75NTR in the developing and mature rodent retina. We further discuss the changes in the expression of NGF and the receptors in experimental models of retinal disorders and diseases like inherited retinitis pigmentosa, retinal detachment, glaucoma, and diabetic retinopathy. Since proNGF is now recognized as a bioactive signaling molecule which induces cell death through p75NTR activation, the role of proNGF in the induction of retinal cell loss under neurodegenerative conditions is also highlighted. In addition, we present the evidences for a potential therapeutic intervention with NGF for the treatment of retinal neurodegenerative diseases. Different strategies have been developed and experimentally tested in mice and rats in order to reduce cell loss and Müller cell gliosis, e.g., increasing the availability of endogenous NGF, administration of exogenous NGF, activation of TrkA, and inhibition of p75NTR. Here, we discuss the several lines of evidence supporting a protective effect of NGF on retinal cell loss, with specific emphasis on photoreceptor and retinal ganglion cell degeneration. A better understanding of the mechanisms underlying the effects of NGF and proNGF in the modulation of neurodegeneration and gliosis in the retina will help to develop efficient therapeutic strategies for various retinal diseases.
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Affiliation(s)
| | - Margrit Hollborn
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany
| | - Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany
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5
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Kimura A, Namekata K, Guo X, Harada C, Harada T. Neuroprotection, Growth Factors and BDNF-TrkB Signalling in Retinal Degeneration. Int J Mol Sci 2016; 17:ijms17091584. [PMID: 27657046 PMCID: PMC5037849 DOI: 10.3390/ijms17091584] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 09/01/2016] [Accepted: 09/14/2016] [Indexed: 12/18/2022] Open
Abstract
Neurotrophic factors play key roles in the development and survival of neurons. The potent neuroprotective effects of neurotrophic factors, including brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), glial cell-line derived neurotrophic factor (GDNF) and nerve growth factor (NGF), suggest that they are good therapeutic candidates for neurodegenerative diseases. Glaucoma is a neurodegenerative disease of the eye that causes irreversible blindness. It is characterized by damage to the optic nerve, usually due to high intraocular pressure (IOP), and progressive degeneration of retinal neurons called retinal ganglion cells (RGCs). Current therapy for glaucoma focuses on reduction of IOP, but neuroprotection may also be beneficial. BDNF is a powerful neuroprotective agent especially for RGCs. Exogenous application of BDNF to the retina and increased BDNF expression in retinal neurons using viral vector systems are both effective in protecting RGCs from damage. Furthermore, induction of BDNF expression by agents such as valproic acid has also been beneficial in promoting RGC survival. In this review, we discuss the therapeutic potential of neurotrophic factors in retinal diseases and focus on the differential roles of glial and neuronal TrkB in neuroprotection. We also discuss the role of neurotrophic factors in neuroregeneration.
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Affiliation(s)
- Atsuko Kimura
- Visual Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
| | - Kazuhiko Namekata
- Visual Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
| | - Xiaoli Guo
- Visual Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
| | - Chikako Harada
- Visual Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
| | - Takayuki Harada
- Visual Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
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6
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Campbell C, Beug S, Nickerson PEB, Peng J, Mazerolle C, Bassett EA, Ringuette R, Jama FA, Morales C, Christ A, Wallace VA. Sortilin regulates sorting and secretion of Sonic hedgehog. J Cell Sci 2016; 129:3832-3844. [PMID: 27632999 DOI: 10.1242/jcs.183541] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 08/26/2016] [Indexed: 01/03/2023] Open
Abstract
Sonic Hedgehog (Shh) is a secreted morphogen that is an essential regulator of patterning and growth. The Shh full-length protein undergoes autocleavage in the endoplasmic reticulum to generate the biologically active N-terminal fragment (ShhN), which is destined for secretion. We identified sortilin (Sort1), a member of the VPS10P-domain receptor family, as a new Shh trafficking receptor. We demonstrate that Sort-Shh interact by performing coimmunoprecipitation and proximity ligation assays in transfected cells and that they colocalize at the Golgi. Sort1 overexpression causes re-distribution of ShhN and, to a lesser extent, of full-length Shh to the Golgi and reduces Shh secretion. We show loss of Sort1 can partially rescue Hedgehog-associated patterning defects in a mouse model that is deficient in Shh processing, and we show that Sort1 levels negatively regulate anterograde Shh transport in axons in vitro and Hedgehog-dependent axon-glial interactions in vivo Taken together, we conclude that Shh and Sort1 can interact at the level of the Golgi and that Sort1 directs Shh away from the pathways that promote its secretion.
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Affiliation(s)
- Charles Campbell
- Regenerative Medicine Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6 Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5
| | - Shawn Beug
- Regenerative Medicine Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6 Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5
| | - Philip E B Nickerson
- Vision Science Division, Krembil Research Institute, University Health Network and Department of Ophthalmology and Vision Sciences, University of Toronto, 60 Leonard Street, Toronto ON M5T 2S8
| | - Jimmy Peng
- Department of Biology, McGill University, 1205 Ave Docteur Penfield Room W4/8, Montreal, Quebec, Canada H3A 1B1 Institut de recherches cliniques de Montréal (IRCM), 110 Avenue des Pins Ouest, Montréal, Quebec, Canada H2W 1R7
| | - Chantal Mazerolle
- Regenerative Medicine Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6
| | - Erin A Bassett
- Regenerative Medicine Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6
| | - Randy Ringuette
- Regenerative Medicine Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6 Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5
| | - Fadumo A Jama
- Regenerative Medicine Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6 Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5
| | - Carlos Morales
- Department of Anatomy and Cell Biology, McGill University, 3640 Rue University, Montréal, Quebec, Canada H3A 0C7
| | - Annabel Christ
- Max-Delbrück-Center for Molecular Medicine, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Valerie A Wallace
- Regenerative Medicine Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6 Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5 Vision Science Division, Krembil Research Institute, University Health Network and Department of Ophthalmology and Vision Sciences, University of Toronto, 60 Leonard Street, Toronto ON M5T 2S8
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7
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Trigos AS, Longart M, García L, Castillo C, Forsyth P, Medina R. ProNGF derived from rat sciatic nerves downregulates neurite elongation and axon specification in PC12 cells. Front Cell Neurosci 2015; 9:364. [PMID: 26441535 PMCID: PMC4569732 DOI: 10.3389/fncel.2015.00364] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 09/02/2015] [Indexed: 01/19/2023] Open
Abstract
Several reports have shown that a sciatic nerve conditioned media (CM) causes neuronal-like differentiation in PC12 cells. This differentiation is featured by neurite outgrowth, which are exclusively dendrites, without axon or sodium current induction. In previous studies, our group reported that the CM supplemented with a generic inhibitor for tyrosine kinase receptors (k252a) enhanced the CM-induced morphological differentiation upregulating neurite outgrowth, axonal formation and sodium current elicitation. Sodium currents were also induced by depletion of endogenous precursor of nerve growth factorr (proNGF) from the CM (pNGFd-CM). Given that sodium currents, neurite outgrowth and axon specification are important features of neuronal differentiation, in the current manuscript, first we investigated if proNGF was hindering the full PC12 cell neuronal-like differentiation. Second, we studied the effects of exogenous wild type (pNGFwt) and mutated (pNGFmut) proNGF isoforms over sodium currents and whether or not their addition to the pNGFd-CM would prevent sodium current elicitation. Third, we investigated if proNGF was exerting its negative regulation through the sortilin receptor, and for this, the proNGF action was blocked with neurotensin (NT), a factor known to compete with proNGF for sortilin. Thereby, here we show that pNGFd-CM enhanced cell differentiation, cell proportion with long neurites, total neurite length, induced axonal formation and sodium current elicitation. Interestingly, treatment of PC12 cells with wild type or mutated proNGF isoforms elicited sodium currents. Supplementing pNGFd-CM with pNGFmut reduced 35% the sodium currents. On the other hand, pNGFd-CM+pNGFwt induced larger sodium currents than pNGFd-CM. Finally, treatments with CM supplemented with NT showed that sortilin was mediating proNGF negative regulation, since its blocking induced similar effects than the pNGFd-CM treatment. Altogether, our results suggest that proNGF within the CM, is one of the main inhibitors of full neuronal differentiation, acting through sortilin receptor.
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Affiliation(s)
- Anna Sofía Trigos
- Unidad de Neurociencias, Instituto de Estudios Avanzados (IDEA) Caracas, Venezuela ; Departamento de Biología Celular, Universidad Simón Bolívar (USB) Caracas, Venezuela
| | - Marines Longart
- Unidad de Neurociencias, Instituto de Estudios Avanzados (IDEA) Caracas, Venezuela
| | - Lisbeth García
- Unidad de Neurociencias, Instituto de Estudios Avanzados (IDEA) Caracas, Venezuela
| | - Cecilia Castillo
- Unidad de Neurociencias, Instituto de Estudios Avanzados (IDEA) Caracas, Venezuela
| | - Patricia Forsyth
- Unidad de Neurociencias, Instituto de Estudios Avanzados (IDEA) Caracas, Venezuela
| | - Rafael Medina
- Unidad de Neurociencias, Instituto de Estudios Avanzados (IDEA) Caracas, Venezuela
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8
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Abstract
The sortilin family of Vps10p-domain receptors includes sortilin, SorLA, and SorCS1-3. These type-I transmembrane receptors predominate in distinct neuronal tissues, but expression is also present in certain specialized non-neuronal cell populations including hepatocytes and cells of the immune system. The biology of sortilins is complex as they participate in both cell signaling and in intracellular protein sorting. Sortilins function physiologically in signaling by pro- and mature neurotrophins in neuronal viability and functionality. Recent genome-wide association studies have linked members to neurological disorders such as Alzheimer's disease and bipolar disorder and outside the nervous system to development of coronary artery disease and type-2 diabetes. Particularly well described are the receptor functions in neuronal signaling by pro- (proNT) and mature (NT) neurotrophins and in the processing/metabolism of amyloid precursor protein (APP).
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Affiliation(s)
- S Glerup
- Danish Research Institute of Translational Neuroscience DANDRITE, Nordic EMBL Partnership, and The Lundbeck Foundation Research Center MIND, Department of Biomedicine, University of Aarhus, Ole Worms Allé 3, 8000, Aarhus C, Denmark
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9
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Duan L, Chen BY, Sun XL, Luo ZJ, Rao ZR, Wang JJ, Chen LW. LPS-induced proNGF synthesis and release in the N9 and BV2 microglial cells: a new pathway underling microglial toxicity in neuroinflammation. PLoS One 2013; 8:e73768. [PMID: 24040063 PMCID: PMC3767823 DOI: 10.1371/journal.pone.0073768] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 07/23/2013] [Indexed: 01/22/2023] Open
Abstract
Purpose While aberrant activation of microglial cells was evidently involved in neuroinflammation and neurotoxicity in the neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease, objective of study was to address if activated microglias deliver their effect by releasing pro-neurotrophins. Materials and methods By in vitro culture of N9 and BV2 cell lines and lipopolysaccharide (LPS) stimulation model, generation and release of proNGF, proBDNF and MMP-9 was studied in the activated microglial cells by immunocytochemistry, western blotting and bioassay methods. Results Activation of microglial cells was observed with obvious increasing iba1-immunoreactivity following LPS stimulation in cell culture. Synthesis and up-regulation of proNGF protein significantly occurred in N9 and BV2 cells 12h-48h after LPS exposure, whereas no significant changes of proBDNF and MMP9 were observed in these microglial cell lines with LPS insult. More interestingly, extracellular release or secretion of proNGF molecule was also detected in culture medium of N9 cells after LPS stimulation. Finally, bioassay using MTT, Hoechst/PI and TUNEL staining in SH-SY5Y cells further confirmed that proNGF treatment could result in apoptotic cell death but it did not significantly influence cell viability of SH-SY5Y cells. Conclusions This in vitro study revealed LPS-stimulated proNGF synthesis and release in activated N9/BV2 microglial cell lines, also suggesting that proNGF may appeal a new pathway or possible mechanism underlying microglial toxicity in the neuroinflammation and a potential target for therapeutic manipulation of the neurodegenerative diseases.
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Affiliation(s)
- Li Duan
- Institute of Neurosciences, The Fourth Military Medical University, Xi’an, China
| | - Bei-Yu Chen
- Department of Orthopedics, Xijing Hospital, The Fourth Military Medical University, Xi’an, China
| | - Xiao-Long Sun
- Institute of Neurosciences, The Fourth Military Medical University, Xi’an, China
- Department of Neurology, Xijing Hospital, The Fourth Military Medical University, Xi’an, China
| | - Zhuo-Jing Luo
- Department of Orthopedics, Xijing Hospital, The Fourth Military Medical University, Xi’an, China
| | - Zhi-Ren Rao
- Institute of Neurosciences, The Fourth Military Medical University, Xi’an, China
| | - Jing-Jie Wang
- Department of Gastroenterology, Tangdu Hospital, The Fourth Military Medical University, Xi’an, China
- * E-mail: (JW); (LC)
| | - Liang-Wei Chen
- Institute of Neurosciences, The Fourth Military Medical University, Xi’an, China
- * E-mail: (JW); (LC)
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Saadipour K, Yang M, Lim Y, Georgiou K, Sun Y, Keating D, Liu J, Wang YR, Gai WP, Zhong JH, Wang YJ, Zhou XF. Amyloid beta1-42
(Aβ42
) up-regulates the expression of sortilin via the p75NTR
/RhoA signaling pathway. J Neurochem 2013; 127:152-62. [DOI: 10.1111/jnc.12383] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 07/04/2013] [Accepted: 07/05/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Khalil Saadipour
- School of Pharmacy and Medical Sciences; Faculty of Health Sciences; University of South Australia; Adelaide SA Australia
- Department of Human Physiology; Centre for Neuroscience; University of Flinders; Adelaide SA Australia
| | - Miao Yang
- School of Pharmacy and Medical Sciences; Faculty of Health Sciences; University of South Australia; Adelaide SA Australia
| | - Yoon Lim
- School of Pharmacy and Medical Sciences; Faculty of Health Sciences; University of South Australia; Adelaide SA Australia
| | - Kristen Georgiou
- School of Pharmacy and Medical Sciences; Faculty of Health Sciences; University of South Australia; Adelaide SA Australia
| | - Ying Sun
- School of Pharmacy and Medical Sciences; Faculty of Health Sciences; University of South Australia; Adelaide SA Australia
| | - Damien Keating
- Department of Human Physiology; Centre for Neuroscience; University of Flinders; Adelaide SA Australia
| | - Jia Liu
- School of Pharmacy and Medical Sciences; Faculty of Health Sciences; University of South Australia; Adelaide SA Australia
| | - Ye-Ran Wang
- School of Pharmacy and Medical Sciences; Faculty of Health Sciences; University of South Australia; Adelaide SA Australia
- Department of Neurology and Center for Clinical Neuroscience; Daping Hospital; Chongqing China
| | - Wei-ping Gai
- Department of Human Physiology; Centre for Neuroscience; University of Flinders; Adelaide SA Australia
| | - Jin-hua Zhong
- School of Pharmacy and Medical Sciences; Faculty of Health Sciences; University of South Australia; Adelaide SA Australia
| | - Yan-Jiang Wang
- Department of Neurology and Center for Clinical Neuroscience; Daping Hospital; Chongqing China
| | - Xin-Fu Zhou
- School of Pharmacy and Medical Sciences; Faculty of Health Sciences; University of South Australia; Adelaide SA Australia
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11
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Xia Y, Chen BY, Sun XL, Duan L, Gao GD, Wang JJ, Yung KKL, Chen LW. Presence of proNGF-sortilin signaling complex in nigral dopamine neurons and its variation in relation to aging, lactacystin and 6-OHDA insults. Int J Mol Sci 2013; 14:14085-104. [PMID: 23880857 PMCID: PMC3742233 DOI: 10.3390/ijms140714085] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 06/20/2013] [Accepted: 06/25/2013] [Indexed: 12/15/2022] Open
Abstract
Growing evidence has shown that proNGF-p75NTR-sortilin signaling might be a crucial factor in neurodegeneration, but it remains unclear if it may function in nigral neurons under aging and disease. The purpose of this study is to examine and quantify proNGF and sortilin expression in the substantia nigra and dynamic changes of aging in lactacystin and 6-hydroxydopamine (6-OHDA) rat models of Parkinson’s disease using immunofluorescence, electronic microscopy, western blot and FLIVO staining methods. The expression of proNGF and sortilin was abundantly and selectively identified in tyrosine hydroxylase (TH)-containing dopamine neurons in the substantia nigra. These proNGF/TH, sortilin/TH-positive neurons were densely distributed in the ventral tier, while they were less distributed in the dorsal tier, where calbindin-D28K-containing neurons were numerously located. A correlated decrease of proNGF, sortilin and TH was also detected during animal aging process. While increase of proNGF, sortilin and cleaved (active) caspase-3 expression was found in the lactacystin model, dynamic proNGF and sortilin changes along with dopamine neuronal loss were demonstrated in the substantia nigra of both the lactacystin and 6-OHDA models. This study has thus revealed the presence of the proNGF-sortilin signaling complex in nigral dopamine neurons and its response to aging, lactacystin and 6-OHDA insults, suggesting that it might contribute to neuronal apoptosis or neurodegeneration during pathogenesis and disease progression of Parkinson’s disease; the underlying mechanism and key signaling pathways involved warrant further investigation.
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Affiliation(s)
- Yi Xia
- Institute of Neurosciences, Fourth Military Medical University, Xi’an 710032, China; E-Mails: (Y.X.); (X.-L.S.); (L.D.)
- Department of Neurosurgery, Tangdou Hospital, Fourth Military Medical University, Xi’an 710038, China; E-Mail:
| | - Bei-Yu Chen
- Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi’an 710032, China; E-Mail:
| | - Xiao-Long Sun
- Institute of Neurosciences, Fourth Military Medical University, Xi’an 710032, China; E-Mails: (Y.X.); (X.-L.S.); (L.D.)
| | - Li Duan
- Institute of Neurosciences, Fourth Military Medical University, Xi’an 710032, China; E-Mails: (Y.X.); (X.-L.S.); (L.D.)
| | - Guo-Dong Gao
- Department of Neurosurgery, Tangdou Hospital, Fourth Military Medical University, Xi’an 710038, China; E-Mail:
| | - Jing-Jie Wang
- Department of Gastroenterology, Tangdou Hospital, Fourth Military Medical University, Xi’an 710038, China
- Authors to whom correspondence should be addressed; E-Mails: (J.-J.W.); (L.-W.C.); Tel.: +86-29-8477-6840 (L.-W.C.); Fax: +86-29-8324-6270 (L.-W.C.)
| | - Ken Kam-Lin Yung
- Department of Biology, Baptist University of Hong Kong, Hong Kong, China; E-Mail:
| | - Liang-Wei Chen
- Institute of Neurosciences, Fourth Military Medical University, Xi’an 710032, China; E-Mails: (Y.X.); (X.-L.S.); (L.D.)
- Authors to whom correspondence should be addressed; E-Mails: (J.-J.W.); (L.-W.C.); Tel.: +86-29-8477-6840 (L.-W.C.); Fax: +86-29-8324-6270 (L.-W.C.)
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12
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Sortilin participates in light-dependent photoreceptor degeneration in vivo. PLoS One 2012; 7:e36243. [PMID: 22558402 PMCID: PMC3338683 DOI: 10.1371/journal.pone.0036243] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2011] [Accepted: 04/03/2012] [Indexed: 11/20/2022] Open
Abstract
Both proNGF and the neurotrophin receptor p75 (p75NTR) are known to regulate photoreceptor cell death caused by exposure of albino mice to intense illumination. ProNGF-induced apoptosis requires the participation of sortilin as a necessary p75NTR co-receptor, suggesting that sortilin may participate in the photoreceptor degeneration triggered by intense lighting. We report here that light-exposed albino mice showed sortilin, p75NTR, and proNGF expression in the outer nuclear layer, the retinal layer where photoreceptor cell bodies are located. In addition, cone progenitor-derived 661W cells subjected to intense illumination expressed sortilin and p75NTR and released proNGF into the culture medium. Pharmacological blockade of sortilin with either neurotensin or the “pro” domain of proNGF (pro-peptide) favored the survival of 661W cells subjected to intense light. In vivo, the pro-peptide attenuated retinal cell death in light-exposed albino mice. We propose that an auto/paracrine proapoptotic mechanism based on the interaction of proNGF with the receptor complex p75NTR/sortilin participates in intense light-dependent photoreceptor cell death. We therefore propose sortilin as a putative target for intervention in hereditary retinal dystrophies.
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13
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Nykjaer A, Willnow TE. Sortilin: a receptor to regulate neuronal viability and function. Trends Neurosci 2012; 35:261-70. [DOI: 10.1016/j.tins.2012.01.003] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Revised: 01/08/2012] [Accepted: 01/10/2012] [Indexed: 11/26/2022]
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14
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Armugam A, Koh DCI, Ching CS, Chandrasekaran K, Kaur P, Jeyaseelan K. Pro-domain in precursor nerve growth factor mediates cell death. Neurochem Int 2012; 60:852-63. [PMID: 22480846 DOI: 10.1016/j.neuint.2012.03.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 03/05/2012] [Accepted: 03/08/2012] [Indexed: 11/30/2022]
Abstract
Nerve growth factor (NGF) is synthesized as a precursor, proNGF that undergoes post-translational processing to generate the biologically active mature NGF. While the neurotrophic function of NGF is well established, the activity of the proNGF precursor is still unclear. In this study, we have cloned the pro-domain of the precursor NGF molecule and have elucidated its function. We have used both mature and the furin resistant pro((R/G))NGF as controls in our experiments. Both pro((R/G))NGF and mature NGF (NGF) exhibited neurotrophic activity on PC12 cells while the pro-domain itself promoted cell death. The pro-domain, has been found to mediate apoptosis possibly by promoting the formation of a signaling complex comprising of endogenous p75(NTR) receptor, Bim/Bcl2 group of proteins and JNK and MEK1/2 signaling pathways.
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Affiliation(s)
- Arunmozhiarasi Armugam
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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15
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Abstract
Dock3, a new member of the guanine nucleotide exchange factors, causes cellular morphological changes by activating the small GTPase Rac1. Overexpression of Dock3 in neural cells promotes axonal outgrowth downstream of brain-derived neurotrophic factor (BDNF) signaling. We previously showed that Dock3 forms a complex with Fyn and WASP (Wiskott-Aldrich syndrome protein) family verprolin-homologous (WAVE) proteins at the plasma membrane, and subsequent Rac1 activation promotes actin polymerization. Here we show that Dock3 binds to and inactivates glycogen synthase kinase-3β (GSK-3β) at the plasma membrane, thereby increasing the nonphosphorylated active form of collapsin response mediator protein-2 (CRMP-2), which promotes axon branching and microtubule assembly. Exogenously applied BDNF induced the phosphorylation of GSK-3β and dephosphorylation of CRMP-2 in hippocampal neurons. Moreover, increased phosphorylation of GSK-3β was detected in the regenerating axons of transgenic mice overexpressing Dock3 after optic nerve injury. These results suggest that Dock3 plays important roles downstream of BDNF signaling in the CNS, where it regulates cell polarity and promotes axonal outgrowth by stimulating dual pathways: actin polymerization and microtubule assembly.
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16
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Le Moan N, Houslay DM, Christian F, Houslay MD, Akassoglou K. Oxygen-dependent cleavage of the p75 neurotrophin receptor triggers stabilization of HIF-1α. Mol Cell 2011; 44:476-90. [PMID: 22055192 PMCID: PMC3212815 DOI: 10.1016/j.molcel.2011.08.033] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Revised: 05/23/2011] [Accepted: 08/15/2011] [Indexed: 12/23/2022]
Abstract
Homeostatic control of oxygen availability allows cells to survive oxygen deprivation. Although the transcription factor hypoxia-inducible factor 1α (HIF-1α) is the main regulator of the hypoxic response, the upstream mechanisms required for its stabilization remain elusive. Here, we show that p75 neurotrophin receptor (p75(NTR)) undergoes hypoxia-induced γ-secretase-dependent cleavage to provide a positive feed-forward mechanism required for oxygen-dependent HIF-1α stabilization. The intracellular domain of p75(NTR) directly interacts with the evolutionarily conserved zinc finger domains of the E3 RING ubiquitin ligase Siah2 (seven in absentia homolog 2), which regulates HIF-1α degradation. p75(NTR) stabilizes Siah2 by decreasing its auto-ubiquitination. Genetic loss of p75(NTR) dramatically decreases Siah2 abundance, HIF-1α stabilization, and induction of HIF-1α target genes in hypoxia. p75(NTR-/-) mice show reduced HIF-1α stabilization, vascular endothelial growth factor (VEGF) expression, and neoangiogenesis after retinal hypoxia. Thus, hypoxia-induced intramembrane proteolysis of p75(NTR) constitutes an apical oxygen-dependent mechanism to control the magnitude of the hypoxic response.
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Affiliation(s)
- Natacha Le Moan
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA
| | - Daniel M. Houslay
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA
| | - Frank Christian
- Molecular Pharmacology Group, Biochemistry & Molecular Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - Miles D. Houslay
- Molecular Pharmacology Group, Biochemistry & Molecular Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - Katerina Akassoglou
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA
- Department of Neurology, University of California, San Francisco, CA 94158, USA
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17
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Zeng F, Lu JJ, Zhou XF, Wang YJ. Roles of p75NTR in the pathogenesis of Alzheimer's disease: A novel therapeutic target. Biochem Pharmacol 2011; 82:1500-9. [DOI: 10.1016/j.bcp.2011.06.040] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 06/25/2011] [Accepted: 06/28/2011] [Indexed: 12/17/2022]
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18
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Chen CKM, Chan NL, Wang AHJ. The many blades of the β-propeller proteins: conserved but versatile. Trends Biochem Sci 2011; 36:553-61. [PMID: 21924917 DOI: 10.1016/j.tibs.2011.07.004] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Revised: 07/14/2011] [Accepted: 07/18/2011] [Indexed: 11/20/2022]
Abstract
The β-propeller is a highly symmetrical structure with 4-10 repeats of a four-stranded antiparallel β-sheet motif. Although β-propeller proteins with different blade numbers all adopt disc-like shapes, they are involved in a diverse set of functions, and defects in this family of proteins have been associated with human diseases. However, it has remained ambiguous how variations in blade number could alter the function of β-propellers. In addition to the regularly arranged β-propeller topology, a recently discovered β-pinwheel propeller has been found. Here, we review the structural and functional diversity of β-propeller proteins, including β-pinwheels, as well as recent advances in the typical and atypical propeller structures.
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Affiliation(s)
- Cammy K-M Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan
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19
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Evans SF, Irmady K, Ostrow K, Kim T, Nykjaer A, Saftig P, Blobel C, Hempstead BL. Neuronal brain-derived neurotrophic factor is synthesized in excess, with levels regulated by sortilin-mediated trafficking and lysosomal degradation. J Biol Chem 2011; 286:29556-67. [PMID: 21730062 DOI: 10.1074/jbc.m111.219675] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) regulates neuronal differentiation, synaptic plasticity, and morphology, and modest changes in BDNF levels results in complex behavioral phenotypes. BDNF levels and intracellular localization in neurons are regulated by multiple mechanisms, including use of distinct promoters, mRNA and protein transport, and regulated cleavage of proBDNF to mature BDNF. Sortilin is an intracellular chaperone that binds to the prodomain of BDNF to traffic it to the regulated secretory pathway. However, sortilin binds to numerous ligands and plays a major role in mannose 6-phosphate receptor-independent transport of lysosomal hydrolases utilizing motifs in the intracellular domain that mediate trafficking from the Golgi and late endosomes. Sortilin is modified by ectodomain shedding, although the biological implications of this are not known. Here we demonstrate that ADAM10 is the preferred protease to cleave sortilin in the extracellular stalk region, to release the ligand binding sortilin ectodomain from the transmembrane and cytoplasmic domains. We identify sortilin shedding at the cell surface and in an intracellular compartment. Both sortilin and BDNF are trafficked to and degraded by the lysosome in neurons, and this is dependent upon the sortilin cytoplasmic tail. Indeed, expression of the sortilin ectodomain, which corresponds to the domain released after shedding, impairs lysosomal targeting and degradation of BDNF. These findings characterize the regulation of sortilin shedding and identify a novel mechanism by which sortilin ectodomain shedding acts as a regulatory switch for delivery of BDNF to the secretory pathway or to the lysosome, thus modulating the bioavailability of endogenous BDNF.
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Affiliation(s)
- Sarah Felice Evans
- Graduate Program in Neuroscience, Weill Medical College of Cornell University, New York, New York 10065, USA
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20
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Teng KK, Felice S, Kim T, Hempstead BL. Understanding proneurotrophin actions: Recent advances and challenges. Dev Neurobiol 2010; 70:350-9. [PMID: 20186707 DOI: 10.1002/dneu.20768] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Neurotrophins are initially synthesized as larger precursors (proneurotrophins), which undergo proteolytic cleavage to yield mature forms. Although the functions of the mature neurotrophins have been well established during neural development and in the adult nervous system, roles for the proneurotrophins in developmental and injury-induced cell death, as well as in synaptic plasticity, have only recently been appreciated. Interestingly, both mature neurotrophins and proneurotrophins utilize dual-receptor complexes to mediate their actions. The mature neurotrophin coreceptors consist of the Trk receptor tyrosine kinases and p75(NTR), wherein Trk transduces survival and differentiative signaling, and p75(NTR) modulates the affinity and selectivity of Trk activation. On the other hand, proneurotrophins engage p75(NTR) and the structurally distinct coreceptor sortilin, to initiate p75(NTR)-dependent signal transduction cascade. Although the specificity of mature neurotrophins vs. proneurotrophins actions is due in part to the formation of distinct coreceptor complexes, a number of recent studies highlight how different p75(NTR)-mediated cellular actions are modulated. Here, we review emerging evidence for a novel transmembrane mechanism for ligand-specific p75(NTR) activation and several mechanisms by which p75(NTR)-dependent apoptotic and nonapoptotic responses can be selective activated.
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Affiliation(s)
- Kenneth K Teng
- Department of Medicine, Weill Cornell Medical College, New York, New York 10065, USA
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21
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Dock3 induces axonal outgrowth by stimulating membrane recruitment of the WAVE complex. Proc Natl Acad Sci U S A 2010; 107:7586-91. [PMID: 20368433 DOI: 10.1073/pnas.0914514107] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Atypical Rho-guanine nucleotide exchange factors (Rho-GEFs) that contain Dock homology regions (DHR-1 and DHR-2) are expressed in a variety of tissues; however, their functions and mechanisms of action remain unclear. We identify key conserved amino acids in the DHR-2 domain that are critical for the catalytic activity of Dock-GEFs (Dock1-4). We further demonstrate that Dock-GEFs directly associate with WASP family verprolin-homologous (WAVE) proteins through the DHR-1 domain. Brain-derived neurotrophic factor (BDNF)-TrkB signaling recruits the Dock3/WAVE1 complex to the plasma membrane, whereupon Dock3 activates Rac and dissociates from the WAVE complex in a phosphorylation-dependent manner. BDNF induces axonal sprouting through Dock-dependent Rac activation, and adult transgenic mice overexpressing Dock3 exhibit enhanced optic nerve regeneration after injury without affecting WAVE expression levels. Our results highlight a unique mechanism through which Dock-GEFs achieve spatial and temporal restriction of WAVE signaling, and identify Dock-GEF activity as a potential therapeutic target for axonal regeneration.
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22
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Serup Andersen O, Boisguerin P, Glerup S, Skeldal S, Volkmer R, Willnow TE, Nykjaer A, Andersen OM. Identification of a linear epitope in sortilin that partakes in pro-neurotrophin binding. J Biol Chem 2010; 285:12210-22. [PMID: 20159974 DOI: 10.1074/jbc.m109.062364] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Sortilin acts as a cell surface receptor for pro-neurotrophins (pro-NT) that upon complex formation with the p75 neurotrophin receptor (p75(NTR)) is able to signal neuronal cell death. Here we screened a sortilin peptide library comprising 16-mer overlapping sequences for binding of the pro-domains of nerve growth factor and brain-derived neurotrophic factor. We find that a linear surface-exposed sequence, (163)RIFRSSDFAKNF(174), constitutes an important pro-NT binding epitope in sortilin. Systematic mutational analysis revealed residues Arg(163), Phe(165), Arg(166), and Phe(170) to be critical for the interaction. Expression of a sortilin mutant in which these four amino acids were substituted by alanines disrupted pro-NT binding without affecting receptor heterodimerization with p75(NTR) or binding of ligands that selectively engages the centrally located tunnel in the beta-propeller of sortilin. We furthermore demonstrate that a peptide comprising the ligand-binding epitope can prevent pro-NT-induced apoptosis in RN22 schwannoma cells.
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Affiliation(s)
- Olga Serup Andersen
- Department of Medical Biochemistry, Membrane Receptors in Neuronal Disease (MIND) Center, University of Aarhus, OleWorms Allé, Aarhus C, Denmark
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23
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Feng D, Kim T, Ozkan E, Light M, Torkin R, Teng KK, Hempstead BL, Garcia KC. Molecular and structural insight into proNGF engagement of p75NTR and sortilin. J Mol Biol 2009; 396:967-84. [PMID: 20036257 PMCID: PMC2847487 DOI: 10.1016/j.jmb.2009.12.030] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Accepted: 12/15/2009] [Indexed: 12/21/2022]
Abstract
Nerve growth factor (NGF) is initially synthesized as a precursor, proNGF, that is cleaved to release its C-terminal mature form. Recent studies suggested that proNGF is not an inactive precursor but acts as a signaling ligand distinct from its mature counterpart. proNGF and mature NGF initiate opposing biological responses by utilizing both distinct and shared receptor components. In this study, we carried out structural and biochemical characterization of proNGF interactions with p75NTR and sortilin. We crystallized proNGF complexed to p75NTR and present the structure at 3.75-A resolution. The structure reveals a 2:2 symmetric binding mode, as compared with the asymmetric structure of a previously reported crystal structure of mature NGF complexed to p75NTR and the 2:2 symmetric complex of neurotrophin-3 (NT-3) and p75NTR. Here, we discuss the possible origins and implications of the different stoichiometries. In the proNGF-p75NTR complex, the pro regions of proNGF are mostly disordered and two hairpin loops (loop 2) at the top of the NGF dimer have undergone conformational changes in comparison with mature NT structures, suggesting possible interactions with the propeptide. We further explored the binding characteristics of proNGF to sortilin using surface plasmon resonance and cell-based assays and determined that calcium ions promote the formation of a stable ternary complex of proNGF-sortilin-p75NTR. These results, together with those of previous structural and mechanistic studies of NT-receptor interactions, suggest the potential for distinct signaling activities through p75NTR mediated by different NT-induced conformational changes.
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Affiliation(s)
- Dan Feng
- Department of Cellular and Molecular Physiology, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
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24
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Yano H, Torkin R, Martin LA, Chao MV, Teng KK. Proneurotrophin-3 is a neuronal apoptotic ligand: evidence for retrograde-directed cell killing. J Neurosci 2009; 29:14790-802. [PMID: 19940174 PMCID: PMC2824605 DOI: 10.1523/jneurosci.2059-09.2009] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Revised: 09/01/2009] [Accepted: 10/13/2009] [Indexed: 12/20/2022] Open
Abstract
Although mature neurotrophins are well described trophic factors that elicit retrograde survival signaling, the precursor forms of neurotrophins (i.e., proneurotrophins) can function as high-affinity apoptotic ligands for selected neural populations. An outstanding question is whether target-derived proneurotrophins might affect neuronal survival/death decisions through a retrograde transport mechanism. Since neurotrophin-3 (NT-3) is highly expressed in non-neural tissues that receive peripheral innervation, we investigated the localized actions of its precursor (proNT-3) on sympathetic neurons in the present study. Pharmacological inhibition of intracellular furin proteinase activity in 293T cells resulted in proNT-3 release instead of mature NT-3, whereas membrane depolarization in cerebellar granule neurons stimulated endogenous proNT-3 secretion, suggesting that proNT-3 is an inducible bona fide ligand in the nervous system. Our data also indicate that recombinant proNT-3 induced sympathetic neuron death that is p75(NTR)- and sortilin-dependent, with hallmark features of apoptosis including JNK (c-Jun N-terminal kinase) activation and nuclear fragmentation. Using compartmentalized culture systems that segregate neuronal cell bodies from axons, proNT-3, acting within the distal axon compartment, elicited sympathetic neuron death and overrode the survival-promoting actions of NGF. Together, these results raise the intriguing possibility that dysregulation of proneurotrophin processing/release by innervated targets can be deleterious to the neurons projecting to these sites.
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Affiliation(s)
- Hiroko Yano
- Molecular Neurobiology Program, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York 10016
| | - Risa Torkin
- Department of Medicine, Weill Cornell Medical College, New York, New York 10065, and
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
| | - Laura Andrés Martin
- Department of Medicine, Weill Cornell Medical College, New York, New York 10065, and
| | - Moses V. Chao
- Molecular Neurobiology Program, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York 10016
| | - Kenneth K. Teng
- Department of Medicine, Weill Cornell Medical College, New York, New York 10065, and
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25
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Kim T, Hempstead BL. NRH2 is a trafficking switch to regulate sortilin localization and permit proneurotrophin-induced cell death. EMBO J 2009; 28:1612-23. [PMID: 19407813 DOI: 10.1038/emboj.2009.118] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Accepted: 03/30/2009] [Indexed: 12/25/2022] Open
Abstract
Proneurotrophins mediate neuronal apoptosis using a dual receptor complex of sortilin and p75(NTR). Although p75(NTR) is highly expressed on the plasma membrane and accessible to proneurotrophin ligands, sortilin is primarily localized to intracellular membranes, limiting the formation of a cell surface co-receptor complex. Here, we show that the mammalian p75(NTR) homologue NRH2 critically regulates the expression of sortilin on the neuronal cell surface and promotes p75(NTR) and sortilin receptor complex formation, rendering cells responsive to proneurotrophins. This is accomplished by interactions between the cytoplasmic domains of NRH2 and sortilin that impair lysosomal degradation of sortilin. In proneurotrophin-responsive neurons, acute silencing of endogenous NRH2 significantly reduces cell surface-expressed sortilin and abolishes proneurotrophin-induced neuronal death. Thus, these data suggest that NRH2 acts as a trafficking switch to impair lysosomal-dependant sortilin degradation and to redistribute sortilin to the cell surface, rendering p75(NTR)-expressing cells susceptible to proneurotrophin-induced death.
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Affiliation(s)
- Taeho Kim
- Graduate Program in Neuroscience, Weill Medical College of Cornell University, New York, NY 10065, USA
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26
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Ligands bind to Sortilin in the tunnel of a ten-bladed β-propeller domain. Nat Struct Mol Biol 2009; 16:96-8. [DOI: 10.1038/nsmb.1543] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Accepted: 12/03/2008] [Indexed: 11/08/2022]
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27
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VPS10P-domain receptors — regulators of neuronal viability and function. Nat Rev Neurosci 2008; 9:899-909. [DOI: 10.1038/nrn2516] [Citation(s) in RCA: 189] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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28
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Althaus HH, Klöppner S, Klopfleisch S, Schmitz M. Oligodendroglial Cells and Neurotrophins: A Polyphonic Cantata in Major and Minor. J Mol Neurosci 2008; 35:65-79. [DOI: 10.1007/s12031-008-9053-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Accepted: 01/25/2008] [Indexed: 01/12/2023]
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29
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Arnett MG, Ryals JM, Wright DE. Pro-NGF, sortilin, and p75NTR: potential mediators of injury-induced apoptosis in the mouse dorsal root ganglion. Brain Res 2007; 1183:32-42. [PMID: 17964555 PMCID: PMC2156563 DOI: 10.1016/j.brainres.2007.09.051] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Revised: 09/07/2007] [Accepted: 09/12/2007] [Indexed: 11/30/2022]
Abstract
The nerve growth factor precursor (pro-NGF) may function as a death-inducing ligand that mediates its apoptotic effects via p75NTR. Pro-NGF-induced apoptosis is postulated to be dependent upon membrane expression of the sortilin receptor, which interacts with p75NTR to promote a high-affinity binding site for pro-NGF. Here, we explore the expression of pro-NGF, sortilin and p75NTR in the mouse lumbar dorsal root ganglion (DRG) to understand the potential for this trimeric signaling complex to function in injury-induced neuronal death of DRG neurons. Our results reveal the expression of all 3 components within the DRG and that a subpopulation of neurons coexpresses sortilin and p75NTR. Following sciatic nerve transection, the expression of these proteins appears insensitive to injury; however, the majority of small p75NTR-sortilin coexpressing neurons are lost 25 days after sciatic nerve transection. These results propose pro-NGF-induced, p75NTR-sortilin-mediated neuronal death as a critical aspect of nerve injury-induced death in the DRG.
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Affiliation(s)
- Melinda G Arnett
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, 3901 Rainbow Blvd., Kansas City, KS 66160, USA
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