1
|
Visser N, Nelemans LC, He Y, Lourens HJ, Corrales MG, Huls G, Wiersma VR, Schuringa JJ, Bremer E. Signal regulatory protein beta 2 is a novel positive regulator of innate anticancer immunity. Front Immunol 2023; 14:1287256. [PMID: 38116002 PMCID: PMC10729450 DOI: 10.3389/fimmu.2023.1287256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 11/10/2023] [Indexed: 12/21/2023] Open
Abstract
In recent years, the therapeutic (re)activation of innate anticancer immunity has gained prominence, with therapeutic blocking of the interaction of Signal Regulatory Protein (SIRP)-α with its ligand CD47 yielding complete responses in refractory and relapsed B cell lymphoma patients. SIRP-α has as crucial inhibitory role on phagocytes, with e.g., its aberrant activation enabling the escape of cancer cells from immune surveillance. SIRP-α belongs to a family of paired receptors comprised of not only immune-inhibitory, but also putative immune-stimulatory receptors. Here, we report that an as yet uninvestigated SIRP family member, SIRP-beta 2 (SIRP-ß2), is strongly expressed under normal physiological conditions in macrophages and granulocytes at protein level. Endogenous expression of SIRP-ß2 on granulocytes correlated with trogocytosis of cancer cells. Further, ectopic expression of SIRP-ß2 stimulated macrophage adhesion, differentiation and cancer cell phagocytosis as well as potentiated macrophage-mediated activation of T cell Receptor-specific T cell activation. SIRP-ß2 recruited the immune activating adaptor protein DAP12 to positively regulate innate immunity, with the charged lysine 202 of SIRP-ß2 being responsible for interaction with DAP12. Mutation of lysine 202 to leucine lead to a complete loss of the increased adhesion and phagocytosis. In conclusion, SIRP-ß2 is a novel positive regulator of innate anticancer immunity and a potential costimulatory target for innate immunotherapy.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | - Edwin Bremer
- Department of Hematology, University of Groningen, University Medical Center Groningen (UMCG), Groningen, Netherlands
| |
Collapse
|
2
|
Gravina A, Tediashvili G, Zheng Y, Iwabuchi KA, Peyrot SM, Roodsari SZ, Gargiulo L, Kaneko S, Osawa M, Schrepfer S, Deuse T. Synthetic immune checkpoint engagers protect HLA-deficient iPSCs and derivatives from innate immune cell cytotoxicity. Cell Stem Cell 2023; 30:1538-1548.e4. [PMID: 37922880 DOI: 10.1016/j.stem.2023.10.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 08/23/2023] [Accepted: 10/04/2023] [Indexed: 11/07/2023]
Abstract
Immune rejection of allogeneic cell therapeutics remains a major problem for immuno-oncology and regenerative medicine. Allogeneic cell products so far have inferior persistence and efficacy when compared with autologous alternatives. Engineering of hypoimmune cells may greatly improve their therapeutic benefit. We present a new class of agonistic immune checkpoint engagers that protect human leukocyte antigen (HLA)-depleted induced pluripotent stem cell-derived endothelial cells (iECs) from innate immune cells. Engagers with agonistic functionality to their inhibitory receptors TIM3 and SIRPα effectively protect engineered iECs from natural killer (NK) cell and macrophage killing. The SIRPα engager can be combined with truncated CD64 to generate fully immune evasive iECs capable of escaping allogeneic cellular and immunoglobulin G (IgG) antibody-mediated rejection. Synthetic immune checkpoint engagers have high target specificity and lack retrograde signaling in the engineered cells. This modular design allows for the exploitation of more inhibitory immune pathways for immune evasion and could contribute to the advancement of allogeneic cell therapeutics.
Collapse
Affiliation(s)
- Alessia Gravina
- Transplant and Stem Cell Immunobiology (TSI)-Lab, Department of Surgery, University of California, San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143, USA
| | - Grigol Tediashvili
- Transplant and Stem Cell Immunobiology (TSI)-Lab, Department of Surgery, University of California, San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143, USA
| | - Yueting Zheng
- Shinobi Therapeutics, 2 Tower Place, South San Francisco, CA 94080, USA
| | - Kumiko A Iwabuchi
- Shinobi Therapeutics, 2 Tower Place, South San Francisco, CA 94080, USA
| | - Sara M Peyrot
- Shinobi Therapeutics, 2 Tower Place, South San Francisco, CA 94080, USA
| | - Susan Z Roodsari
- Shinobi Therapeutics, 2 Tower Place, South San Francisco, CA 94080, USA
| | - Lauren Gargiulo
- Shinobi Therapeutics, 2 Tower Place, South San Francisco, CA 94080, USA
| | - Shin Kaneko
- Laboratory of Regenerative Immunotherapy, Department of Cell Growth and Differentiation, Center for iPS cell Research, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Mitsujiro Osawa
- Shinobi Therapeutics, Med-Pharm Collaboration Building 46-29, Yoshida-Shimo-Adachi-Cho, Sakyo-Ku, Kyoto, Japan
| | - Sonja Schrepfer
- Transplant and Stem Cell Immunobiology (TSI)-Lab, Department of Surgery, University of California, San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143, USA
| | - Tobias Deuse
- Transplant and Stem Cell Immunobiology (TSI)-Lab, Department of Surgery, University of California, San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143, USA.
| |
Collapse
|
3
|
Hirai H, Hong J, Fujii W, Sanjoba C, Goto Y. Leishmania Infection-Induced Proteolytic Processing of SIRPα in Macrophages. Pathogens 2023; 12:pathogens12040593. [PMID: 37111479 PMCID: PMC10146913 DOI: 10.3390/pathogens12040593] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 04/06/2023] [Accepted: 04/11/2023] [Indexed: 04/29/2023] Open
Abstract
The shedding of cell surface receptors may bring synergistic outcomes through the loss of receptor-mediated cell signaling and competitive binding of the shed soluble receptor to its ligand. Thus, soluble receptors have both biological importance and diagnostic importance as biomarkers in immunological disorders. Signal regulatory protein α (SIRPα), one of the receptors responsible for the 'don't-eat-me' signal, is expressed by myeloid cells where its expression and function are in part regulated by proteolytic cleavage. However, reports on soluble SIRPα as a biomarker are limited. We previously reported that mice with experimental visceral leishmaniasis (VL) manifest anemia and enhanced hemophagocytosis in the spleen accompanied with decreased SIRPα expression. Here, we report increased serum levels of soluble SIRPα in mice infected with Leishmania donovani, a causative agent of VL. Increased soluble SIRPα was also detected in a culture supernatant of macrophages infected with L. donovani in vitro, suggesting the parasite infection promotes ectodomain shedding of SIRPα on macrophages. The release of soluble SIRPα was partially inhibited by an ADAM proteinase inhibitor in both LPS stimulation and L. donovani infection, suggesting a shared mechanism for cleavage of SIRPα in both cases. In addition to the ectodomain shedding of SIRPα, both LPS stimulation and L. donovani infection induced the loss of the cytoplasmic region of SIRPα. Although the effects of these proteolytic processes or changes in SIRPα still remain unclear, these proteolytic regulations on SIRPα during L. donovani infection may explain hemophagocytosis and anemia induced by infection, and serum soluble SIRPα may serve as a biomarker for hemophagocytosis and anemia in VL and the other inflammatory disorders.
Collapse
Affiliation(s)
- Hana Hirai
- Laboratory of Molecular Immunology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Jing Hong
- Laboratory of Molecular Immunology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Wataru Fujii
- Laboratory of Biomedical Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Chizu Sanjoba
- Laboratory of Molecular Immunology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yasuyuki Goto
- Laboratory of Molecular Immunology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| |
Collapse
|
4
|
A Proteome-Wide Effect of PHF8 Knockdown on Cortical Neurons Shows Downregulation of Parkinson's Disease-Associated Protein Alpha-Synuclein and Its Interactors. Biomedicines 2023; 11:biomedicines11020486. [PMID: 36831023 PMCID: PMC9953648 DOI: 10.3390/biomedicines11020486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 01/27/2023] [Accepted: 02/02/2023] [Indexed: 02/10/2023] Open
Abstract
Synaptic dysfunction may underlie the pathophysiology of Parkinson's disease (PD), a presently incurable condition characterized by motor and cognitive symptoms. Here, we used quantitative proteomics to study the role of PHD Finger Protein 8 (PHF8), a histone demethylating enzyme found to be mutated in X-linked intellectual disability and identified as a genetic marker of PD, in regulating the expression of PD-related synaptic plasticity proteins. Amongst the list of proteins found to be affected by PHF8 knockdown were Parkinson's-disease-associated SNCA (alpha synuclein) and PD-linked genes DNAJC6 (auxilin), SYNJ1 (synaptojanin 1), and the PD risk gene SH3GL2 (endophilin A1). Findings in this study show that depletion of PHF8 in cortical neurons affects the activity-induced expression of proteins involved in synaptic plasticity, synaptic structure, vesicular release and membrane trafficking, spanning the spectrum of pre-synaptic and post-synaptic transmission. Given that the depletion of even a single chromatin-modifying enzyme can affect synaptic protein expression in such a concerted manner, more in-depth studies will be needed to show whether such a mechanism can be exploited as a potential disease-modifying therapeutic drug target in PD.
Collapse
|
5
|
Jiang D, Burger CA, Akhanov V, Liang JH, Mackin RD, Albrecht NE, Andrade P, Schafer DP, Samuel MA. Neuronal signal-regulatory protein alpha drives microglial phagocytosis by limiting microglial interaction with CD47 in the retina. Immunity 2022; 55:2318-2335.e7. [PMID: 36379210 PMCID: PMC9772037 DOI: 10.1016/j.immuni.2022.10.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 07/15/2022] [Accepted: 10/21/2022] [Indexed: 11/16/2022]
Abstract
Microglia utilize their phagocytic activity to prune redundant synapses and refine neural circuits during precise developmental periods. However, the neuronal signals that control this phagocytic clockwork remain largely undefined. Here, we show that neuronal signal-regulatory protein alpha (SIRPα) is a permissive cue for microglial phagocytosis in the developing murine retina. Removal of neuronal, but not microglial, SIRPα reduced microglial phagocytosis, increased synpase numbers, and impaired circuit function. Conversely, prolonging neuronal SIRPα expression extended developmental microglial phagocytosis. These outcomes depended on the interaction of presynaptic SIRPα with postsynaptic CD47. Global CD47 deficiency modestly increased microglial phagocytosis, while CD47 overexpression reduced it. This effect was rescued by coexpression of neuronal SIRPα or codeletion of neuronal SIRPα and CD47. These data indicate that neuronal SIRPα regulates microglial phagocytosis by limiting microglial SIRPα access to neuronal CD47. This discovery may aid our understanding of synapse loss in neurological diseases.
Collapse
Affiliation(s)
- Danye Jiang
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Courtney A Burger
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Viktor Akhanov
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Justine H Liang
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Robert D Mackin
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Nicholas E Albrecht
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Pilar Andrade
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Dorothy P Schafer
- Department of Neurobiology, Brudnick Neuropsychiatric Research Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Melanie A Samuel
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA.
| |
Collapse
|
6
|
Thomas SS, Wu J, Davogustto G, Holliday MW, Eckel-Mahan K, Verzola D, Garibotto G, Hu Z, Mitch WE, Taegtmeyer H. SIRPα Mediates IGF1 Receptor in Cardiomyopathy Induced by Chronic Kidney Disease. Circ Res 2022; 131:207-221. [PMID: 35722884 PMCID: PMC10010047 DOI: 10.1161/circresaha.121.320546] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Chronic kidney disease (CKD) is characterized by increased myocardial mass despite near-normal blood pressure, suggesting the presence of a separate trigger. A potential driver is SIRPα (signal regulatory protein alpha)-a mediator impairing insulin signaling. The objective of this study is to assess the role of circulating SIRPα in CKD-induced adverse cardiac remodeling. METHODS SIRPα expression was evaluated in mouse models and patients with CKD. Specifically, mutant, muscle-specific, or cardiac muscle-specific SIRPα KO (knockout) mice were examined after subtotal nephrectomy. Cardiac function was assessed by echocardiography. Metabolic responses were confirmed in cultured muscle cells or cardiomyocytes. RESULTS We demonstrate that SIRPα regulates myocardial insulin/IGF1R (insulin growth factor-1 receptor) signaling in CKD. First, in the serum of both mice and patients, SIRPα was robustly secreted in response to CKD. Second, cardiac muscle upregulation of SIRPα was associated with impaired insulin/IGF1R signaling, myocardial dysfunction, and fibrosis. However, both global and cardiac muscle-specific SIRPα KO mice displayed improved cardiac function when compared with control mice with CKD. Third, both muscle-specific or cardiac muscle-specific SIRPα KO mice did not significantly activate fetal genes and maintained insulin/IGF1R signaling with suppressed fibrosis despite the presence of CKD. Importantly, SIRPα directly interacted with IGF1R. Next, rSIRPα (recombinant SIRPα) protein was introduced into muscle-specific SIRPα KO mice reestablishing the insulin/IGF1R signaling activity. Additionally, overexpression of SIRPα in myoblasts and cardiomyocytes impaired pAKT (phosphorylation of AKT) and insulin/IGF1R signaling. Furthermore, myotubes and cardiomyocytes, but not adipocytes treated with high glucose or cardiomyocytes treated with uremic toxins, stimulated secretion of SIRPα in culture media, suggesting these cells are the origin of circulating SIRPα in CKD. Both intracellular and extracellular SIRPα exert biologically synergistic effects impairing intracellular myocardial insulin/IGF1R signaling. CONCLUSIONS Myokine SIRPα expression impairs insulin/IGF1R functions in cardiac muscle, affecting cardiometabolic signaling pathways. Circulating SIRPα constitutes an important readout of insulin resistance in CKD-induced cardiomyopathy.
Collapse
Affiliation(s)
- Sandhya S Thomas
- Nephrology Division, Department of Medicine, Michael E. Debakey VA Medical Center, Houston, TX (S.S.T.).,Nephrology Division, Department of Medicine, Baylor College of Medicine, Houston, TX (S.S.T., J.W., M.W.H., Z.H., W.E.M.)
| | - Jiao Wu
- Nephrology Division, Department of Medicine, Baylor College of Medicine, Houston, TX (S.S.T., J.W., M.W.H., Z.H., W.E.M.)
| | - Giovanni Davogustto
- Cardiology Division, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN (G.D.)
| | - Michael W Holliday
- Nephrology Division, Department of Medicine, Baylor College of Medicine, Houston, TX (S.S.T., J.W., M.W.H., Z.H., W.E.M.)
| | - Kristin Eckel-Mahan
- Center for Metabolic and Degenerative Diseases, Institute of Molecular Medicine, The University of Texas Health Science Center, Houston (K.E.-M.)
| | - Daniela Verzola
- Nephrology Division, Department of Medicine, Università degli Studi di Genova, Genoa, Italy (D.V., G.G.)
| | - Giacomo Garibotto
- Nephrology Division, Department of Medicine, Università degli Studi di Genova, Genoa, Italy (D.V., G.G.)
| | - Zhaoyong Hu
- Nephrology Division, Department of Medicine, Baylor College of Medicine, Houston, TX (S.S.T., J.W., M.W.H., Z.H., W.E.M.)
| | - William E Mitch
- Nephrology Division, Department of Medicine, Baylor College of Medicine, Houston, TX (S.S.T., J.W., M.W.H., Z.H., W.E.M.)
| | - Heinrich Taegtmeyer
- Cardiology Division, Department of Medicine, McGovern Medical School at the University of Texas Health Science Center, Houston (H.T.)
| |
Collapse
|
7
|
Vladimirova YV, Mølmer MK, Antonsen KW, Møller N, Rittig N, Nielsen MC, Møller HJ. A New Serum Macrophage Checkpoint Biomarker for Innate Immunotherapy: Soluble Signal-Regulatory Protein Alpha (sSIRPα). Biomolecules 2022; 12:biom12070937. [PMID: 35883493 PMCID: PMC9312483 DOI: 10.3390/biom12070937] [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] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Revised: 06/24/2022] [Accepted: 06/30/2022] [Indexed: 12/10/2022] Open
Abstract
Background and Aims: The macrophage “don’t eat me” pathway CD47/SIRPα is a target for promising new immunotherapy. We hypothesized that a soluble variant of SIRPα is present in the blood and may function as a biomarker. Methods: Monocyte derived macrophages (MDMs) from human buffy-coats were stimulated into macrophage subtypes by LPS and IFN-γ (M1), IL-4 and IL-13 (M2a), IL-10 (M2c) and investigated using flow cytometry. Soluble SIRPα (sSIRPα) was measured in cell cultures and serum by Western blotting and an optimized ELISA. Serum samples were obtained from 120 healthy individuals and from 8 individuals challenged by an LPS injection. Results: All macrophage phenotypes expressed SIRPα by flowcytometry, and sSIRPα was present in all culture supernatants including unstimulated cells. M1 macrophages expressed the lowest level of SIRPαand released the highest level of sSIRPα (p < 0.05). In vivo, the serum level of sSIRPα increased significantly (p < 0.0001) after an LPS challenge in humans. The median concentration in healthy individuals was 28.7 µg/L (19.8−41.1, 95% reference interval), and 20.5 µg/L in an IFCC certified serum reference material. The protein was stable in serum for prolonged storage and repeated freeze/thawing. Conclusions: We demonstrate that sSIRPα is produced constitutively and the concentration increases upon macrophage activation both in vitro and in vivo. It is present in human serum where it may function as a biomarker for the activity of tumor-associated macrophages (TAMs), and for monitoring the effect of immunotherapy.
Collapse
Affiliation(s)
- Yoanna V. Vladimirova
- Department of Clinical Biochemistry, Aarhus University Hospital, 8200 Aarhus N, Denmark; (Y.V.V.); (M.K.M.); (K.W.A.); (M.C.N.)
| | - Marie K. Mølmer
- Department of Clinical Biochemistry, Aarhus University Hospital, 8200 Aarhus N, Denmark; (Y.V.V.); (M.K.M.); (K.W.A.); (M.C.N.)
| | - Kristian W. Antonsen
- Department of Clinical Biochemistry, Aarhus University Hospital, 8200 Aarhus N, Denmark; (Y.V.V.); (M.K.M.); (K.W.A.); (M.C.N.)
| | - Niels Møller
- Department of Endocrinology and Internal Medicine, Medical/Steno Research Laboratories, Aarhus University Hospital, 8200 Aarhus N, Denmark; (N.M.); (N.R.)
| | - Nikolaj Rittig
- Department of Endocrinology and Internal Medicine, Medical/Steno Research Laboratories, Aarhus University Hospital, 8200 Aarhus N, Denmark; (N.M.); (N.R.)
| | - Marlene C. Nielsen
- Department of Clinical Biochemistry, Aarhus University Hospital, 8200 Aarhus N, Denmark; (Y.V.V.); (M.K.M.); (K.W.A.); (M.C.N.)
| | - Holger J. Møller
- Department of Clinical Biochemistry, Aarhus University Hospital, 8200 Aarhus N, Denmark; (Y.V.V.); (M.K.M.); (K.W.A.); (M.C.N.)
- Department of Clinical Medicine, Aarhus University, 8200 Aarhus N, Denmark
- Correspondence:
| |
Collapse
|
8
|
An activity-dependent determinant of synapse elimination in the mammalian brain. Neuron 2021; 109:1333-1349.e6. [PMID: 33770504 DOI: 10.1016/j.neuron.2021.03.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/26/2021] [Accepted: 03/04/2021] [Indexed: 01/06/2023]
Abstract
To establish functional neural circuits in the brain, synaptic connections are refined by neural activity during development, where active connections are maintained and inactive ones are eliminated. However, the molecular signals that regulate synapse refinement remain to be elucidated. When we inactivate a subset of neurons in the mouse cingulate cortex, their callosal connections are eliminated through activity-dependent competition. Using this system, we identify JAK2 tyrosine kinase as a key regulator of inactive synapse elimination. We show that JAK2 is necessary and sufficient for elimination of inactive connections; JAK2 is activated at inactive synapses in response to signals from other active synapses; STAT1, a substrate of JAK2, mediates inactive synapse elimination; JAK2 signaling is critical for physiological refinement of synapses during normal development; and JAK2 regulates synapse refinement in multiple brain regions. We propose that JAK2 is an activity-dependent switch that serves as a determinant of inactive synapse elimination.
Collapse
|
9
|
Rodríguez Cruz PM, Cossins J, Beeson D, Vincent A. The Neuromuscular Junction in Health and Disease: Molecular Mechanisms Governing Synaptic Formation and Homeostasis. Front Mol Neurosci 2020; 13:610964. [PMID: 33343299 PMCID: PMC7744297 DOI: 10.3389/fnmol.2020.610964] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 10/30/2020] [Indexed: 12/28/2022] Open
Abstract
The neuromuscular junction (NMJ) is a highly specialized synapse between a motor neuron nerve terminal and its muscle fiber that are responsible for converting electrical impulses generated by the motor neuron into electrical activity in the muscle fibers. On arrival of the motor nerve action potential, calcium enters the presynaptic terminal, which leads to the release of the neurotransmitter acetylcholine (ACh). ACh crosses the synaptic gap and binds to ACh receptors (AChRs) tightly clustered on the surface of the muscle fiber; this leads to the endplate potential which initiates the muscle action potential that results in muscle contraction. This is a simplified version of the events in neuromuscular transmission that take place within milliseconds, and are dependent on a tiny but highly structured NMJ. Much of this review is devoted to describing in more detail the development, maturation, maintenance and regeneration of the NMJ, but first we describe briefly the most important molecules involved and the conditions that affect their numbers and function. Most important clinically worldwide, are myasthenia gravis (MG), the Lambert-Eaton myasthenic syndrome (LEMS) and congenital myasthenic syndromes (CMS), each of which causes specific molecular defects. In addition, we mention the neurotoxins from bacteria, snakes and many other species that interfere with neuromuscular transmission and cause potentially fatal diseases, but have also provided useful probes for investigating neuromuscular transmission. There are also changes in NMJ structure and function in motor neuron disease, spinal muscle atrophy and sarcopenia that are likely to be secondary but might provide treatment targets. The NMJ is one of the best studied and most disease-prone synapses in the nervous system and it is amenable to in vivo and ex vivo investigation and to systemic therapies that can help restore normal function.
Collapse
Affiliation(s)
- Pedro M Rodríguez Cruz
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.,Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - Judith Cossins
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.,Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.,Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - Angela Vincent
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.,Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| |
Collapse
|
10
|
Szczurkowska J, Pischedda F, Pinto B, Managò F, Haas CA, Summa M, Bertorelli R, Papaleo F, Schäfer MK, Piccoli G, Cancedda L. NEGR1 and FGFR2 cooperatively regulate cortical development and core behaviours related to autism disorders in mice. Brain 2019; 141:2772-2794. [PMID: 30059965 PMCID: PMC6113639 DOI: 10.1093/brain/awy190] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 06/04/2018] [Indexed: 12/15/2022] Open
Abstract
Autism spectrum disorders are neurodevelopmental conditions with diverse aetiologies, all characterized by common core symptoms such as impaired social skills and communication, as well as repetitive behaviour. Cell adhesion molecules, receptor tyrosine kinases and associated downstream signalling have been strongly implicated in both neurodevelopment and autism spectrum disorders. We found that downregulation of the cell adhesion molecule NEGR1 or the receptor tyrosine kinase fibroblast growth factor receptor 2 (FGFR2) similarly affects neuronal migration and spine density during mouse cortical development in vivo and results in impaired core behaviours related to autism spectrum disorders. Mechanistically, NEGR1 physically interacts with FGFR2 and modulates FGFR2-dependent extracellular signal-regulated kinase (ERK) and protein kinase B (AKT) signalling by decreasing FGFR2 degradation from the plasma membrane. Accordingly, FGFR2 overexpression rescues all defects due to Negr1 knockdown in vivo. Negr1 knockout mice present phenotypes similar to Negr1-downregulated animals. These data indicate that NEGR1 and FGFR2 cooperatively regulate cortical development and suggest a role for defective NEGR1-FGFR2 complex and convergent downstream ERK and AKT signalling in autism spectrum disorders.
Collapse
Affiliation(s)
- Joanna Szczurkowska
- Local Micro-environment and Brain Development Laboratory, Italian Institute of Technology, Genoa, Italy.,Università degli Studi di Genova, Via Balbi, 5, Genoa, Italy
| | - Francesca Pischedda
- Laboratory of Biology of Synapse. Center for Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Bruno Pinto
- Local Micro-environment and Brain Development Laboratory, Italian Institute of Technology, Genoa, Italy.,Bio@SNS, Scuola Normale Superiore, Pisa, Italy
| | - Francesca Managò
- Genetics of Cognition Laboratory, Italian Institute of Technology, Genoa, Italy
| | - Carola A Haas
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Maria Summa
- Department of Drug Discovery and Development, Italian Institute of Technology, Genoa, Italy
| | - Rosalia Bertorelli
- Department of Drug Discovery and Development, Italian Institute of Technology, Genoa, Italy
| | - Francesco Papaleo
- Genetics of Cognition Laboratory, Italian Institute of Technology, Genoa, Italy
| | - Michael K Schäfer
- Department of Anesthesiology and Focus Program Translational Neurosciences, University Medical Center of the Johannes Gutenberg-University Mainz, Germany
| | - Giovanni Piccoli
- Laboratory of Biology of Synapse. Center for Integrative Biology (CIBIO), University of Trento, Trento, Italy.,Dulbecco Telethon Institute, Varese Street 16b - 00185 Rome, Italy
| | - Laura Cancedda
- Local Micro-environment and Brain Development Laboratory, Italian Institute of Technology, Genoa, Italy.,Dulbecco Telethon Institute, Varese Street 16b - 00185 Rome, Italy
| |
Collapse
|
11
|
Nagappan-Chettiar S, Johnson-Venkatesh EM, Umemori H. Tyrosine phosphorylation of the transmembrane protein SIRPα: Sensing synaptic activity and regulating ectodomain cleavage for synapse maturation. J Biol Chem 2018; 293:12026-12042. [PMID: 29914984 DOI: 10.1074/jbc.ra117.001488] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 06/08/2018] [Indexed: 11/06/2022] Open
Abstract
Synapse maturation is a neural activity-dependent process during brain development, in which active synapses preferentially undergo maturation to establish efficient neural circuits in the brain. Defects in this process are implicated in various neuropsychiatric disorders. We have previously reported that a postsynaptic transmembrane protein, signal regulatory protein-α (SIRPα), plays an important role in activity-dependently directing synapse maturation. In the presence of synaptic activity, the ectodomain of SIRPα is cleaved and released and then acts as a retrograde signal to induce presynaptic maturation. However, how SIRPα detects synaptic activity to promote its ectodomain cleavage and synapse maturation is unknown. Here, we show that activity-dependent tyrosine phosphorylation of SIRPα is critical for SIRPα cleavage and synapse maturation. We found that during synapse maturation and in response to neural activity, SIRPα is highly phosphorylated on its tyrosine residues in the hippocampus, a structure critical for learning and memory. Tyrosine phosphorylation of SIRPα was necessary for SIRPα cleavage and presynaptic maturation, as indicated by the fact that a phosphorylation-deficient SIRPα variant underwent much less cleavage and could not drive presynaptic maturation. However, SIRPα phosphorylation did not affect its synaptic localization. Finally, we show that inhibitors of the Src and JAK kinase family suppress neural activity-dependent SIRPα phosphorylation and cleavage. Together, our results indicate that SIRPα phosphorylation serves as a mechanism for detecting synaptic activity and linking it to the ectodomain cleavage of SIRPα, which in turn drives synapse maturation in an activity-dependent manner.
Collapse
Affiliation(s)
- Sivapratha Nagappan-Chettiar
- Department of Neurology, F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts 02115; Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02115
| | - Erin M Johnson-Venkatesh
- Department of Neurology, F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts 02115
| | - Hisashi Umemori
- Department of Neurology, F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts 02115; Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02115.
| |
Collapse
|
12
|
Lieberman OJ, McGuirt AF, Tang G, Sulzer D. Roles for neuronal and glial autophagy in synaptic pruning during development. Neurobiol Dis 2018; 122:49-63. [PMID: 29709573 DOI: 10.1016/j.nbd.2018.04.017] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 03/22/2018] [Accepted: 04/24/2018] [Indexed: 12/29/2022] Open
Abstract
The dendritic protrusions known as spines represent the primary postsynaptic location for excitatory synapses. Dendritic spines are critical for many synaptic functions, and their formation, modification, and turnover are thought to be important for mechanisms of learning and memory. At many excitatory synapses, dendritic spines form during the early postnatal period, and while many spines are likely being formed and removed throughout life, the net number are often gradually "pruned" during adolescence to reach a stable level in the adult. In neurodevelopmental disorders, spine pruning is disrupted, emphasizing the importance of understanding its governing processes. Autophagy, a process through which cytosolic components and organelles are degraded, has recently been shown to control spine pruning in the mouse cortex, but the mechanisms through which autophagy acts remain obscure. Here, we draw on three widely studied prototypical synaptic pruning events to focus on two governing principles of spine pruning: 1) activity-dependent synaptic competition and 2) non-neuronal contributions. We briefly review what is known about autophagy in the central nervous system and its regulation by metabolic kinases. We propose a model in which autophagy in both neurons and non-neuronal cells contributes to spine pruning, and how other processes that regulate spine pruning could intersect with autophagy. We further outline future research directions to address outstanding questions on the role of autophagy in synaptic pruning.
Collapse
Affiliation(s)
- Ori J Lieberman
- Department of Psychiatry, Columbia University Medical Center, New York, NY 10032, United States
| | - Avery F McGuirt
- Department of Psychiatry, Columbia University Medical Center, New York, NY 10032, United States
| | - Guomei Tang
- Department of Neurology, Columbia University Medical Center, New York, NY 10032, United States
| | - David Sulzer
- Department of Psychiatry, Columbia University Medical Center, New York, NY 10032, United States; Department of Neurology, Columbia University Medical Center, New York, NY 10032, United States; Department of Pharmacology, Columbia University Medical Center, New York, NY 10032, United States; Research Foundation for Mental Hygiene, New York State Psychiatric Institute, New York, NY 10032, United States.
| |
Collapse
|
13
|
Nagappan-Chettiar S, Johnson-Venkatesh EM, Umemori H. Activity-dependent proteolytic cleavage of cell adhesion molecules regulates excitatory synaptic development and function. Neurosci Res 2017; 116:60-69. [PMID: 27965136 PMCID: PMC5376514 DOI: 10.1016/j.neures.2016.12.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2016] [Revised: 11/29/2016] [Accepted: 11/30/2016] [Indexed: 01/21/2023]
Abstract
Activity-dependent remodeling of neuronal connections is critical to nervous system development and function. These processes rely on the ability of synapses to detect neuronal activity and translate it into the appropriate molecular signals. One way to convert neuronal activity into downstream signaling is the proteolytic cleavage of cell adhesion molecules (CAMs). Here we review studies demonstrating the mechanisms by which proteolytic processing of CAMs direct the structural and functional remodeling of excitatory glutamatergic synapses during development and plasticity. Specifically, we examine how extracellular proteolytic cleavage of CAMs switches on or off molecular signals to 1) permit, drive, or restrict synaptic maturation during development and 2) strengthen or weaken synapses during adult plasticity. We will also examine emerging studies linking improper activity-dependent proteolytic processing of CAMs to neurological disorders such as schizophrenia, brain tumors, and Alzheimer's disease. Together these findings suggest that the regulation of activity-dependent proteolytic cleavage of CAMs is vital to proper brain development and lifelong function.
Collapse
Affiliation(s)
- Sivapratha Nagappan-Chettiar
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
| | - Erin M Johnson-Venkatesh
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Hisashi Umemori
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA.
| |
Collapse
|
14
|
Pinto MJ, Almeida RD. Puzzling out presynaptic differentiation. J Neurochem 2016; 139:921-942. [PMID: 27315450 DOI: 10.1111/jnc.13702] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 05/27/2016] [Accepted: 06/10/2016] [Indexed: 12/24/2022]
Abstract
Proper brain function in the nervous system relies on the accurate establishment of synaptic contacts during development. Countless synapses populate the adult brain in an orderly fashion. In each synapse, a presynaptic terminal loaded with neurotransmitters-containing synaptic vesicles is perfectly aligned to an array of receptors in the postsynaptic membrane. Presynaptic differentiation, which encompasses the events underlying assembly of new presynaptic units, has seen notable advances in recent years. It is now consensual that as a growing axon encounters the receptive dendrites of its partner, presynaptic assembly will be triggered and specified by multiple postsynaptically-derived factors including soluble molecules and cell adhesion complexes. Presynaptic material that reaches these distant sites by axonal transport in the form of pre-assembled packets will be retained and clustered, ultimately giving rise to a presynaptic bouton. This review focuses on the cellular and molecular aspects of presynaptic differentiation in the central nervous system, with a particular emphasis on the identity of the instructive factors and the intracellular processes used by neuronal cells to assemble functional presynaptic terminals. We provide a detailed description of the mechanisms leading to the formation of new presynaptic terminals. In brief, soma-derived packets of pre-assembled material are trafficked to distant axonal sites. Synaptogenic factors from dendritic or glial provenance activate downstream intra-axonal mediators to trigger clustering of passing material and their correct organization into a new presynaptic bouton. This article is part of a mini review series: "Synaptic Function and Dysfunction in Brain Diseases".
Collapse
Affiliation(s)
- Maria J Pinto
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,PhD Programme in Experimental Biology and Biomedicine (PDBEB), Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Ramiro D Almeida
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,School of Allied Health Technologies, Polytechnic Institute of Oporto, Vila Nova de Gaia, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| |
Collapse
|
15
|
Kumral A, Iscan B, Engur D, Tuzun F, Ozbal S, Ergur BU, Kaynak Turkmen M, Duman N, Ozkan H. Intranasal surfactant protein D as neuroprotective rescue in a neonatal rat model of periventricular leukomalacia. J Matern Fetal Neonatal Med 2016; 30:446-451. [PMID: 27109442 DOI: 10.1080/14767058.2016.1174996] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
BACKGROUND Periventricular leukomalacia (PVL) is the leading cause of neurocognitive deficits in children with prematurity. We previously hypothesized that surfactant protein D (SPD) with its ability to bind toll-like receptors may have a possible ameliorating effect in PVL. METHODS Three groups were defined as: LPS-administered and postnatal intranasal saline administered group, LPS-administered and postnatal intranasal SPD-treated group, and control group. Twenty-eight offspring rats were reared with their dams until their sacrifice for histological evaluation on day 7. RESULTS A significant loss of brain weight occurred in the LPS group compared with controls. The postnatal intranasal SPD treatment significantly reduced the number of TUNEL-positive cells in the periventricular white matter as compared with the LPS-treated group. Compared with the control group, LPS injection in the rat brain significantly reduced the MBP-positive staining. Postnatal SPD treatment greatly prevented LPS-stimulated loss of MBP staining. CONCLUSIONS Present study demonstrated a neuroprotective effect of SPD in a rat model of PVL. Our results offer future implications towards increasing our understanding about multifactorial mechanisms underlying periventricular leukomalacia and developing plausible therapeutic strategies in order to prevent neurocognitive deficits in preterm infants.
Collapse
Affiliation(s)
- Abdullah Kumral
- a Department of Pediatrics , Division of Neonatology, School of Medicine, Dokuz Eylul University , Izmir , Turkey
| | - Burcin Iscan
- a Department of Pediatrics , Division of Neonatology, School of Medicine, Dokuz Eylul University , Izmir , Turkey
| | - Defne Engur
- b Department of Pediatrics , Division of Neonatology, School of Medicine, Adnan Menderes University , Aydin , Turkey , and
| | - Funda Tuzun
- a Department of Pediatrics , Division of Neonatology, School of Medicine, Dokuz Eylul University , Izmir , Turkey
| | - Seda Ozbal
- c Department of Histology , School of Medicine, Dokuz Eylul University , Izmir , Turkey
| | - Bekir Ugur Ergur
- c Department of Histology , School of Medicine, Dokuz Eylul University , Izmir , Turkey
| | - Munevver Kaynak Turkmen
- b Department of Pediatrics , Division of Neonatology, School of Medicine, Adnan Menderes University , Aydin , Turkey , and
| | - Nuray Duman
- a Department of Pediatrics , Division of Neonatology, School of Medicine, Dokuz Eylul University , Izmir , Turkey
| | - Hasan Ozkan
- a Department of Pediatrics , Division of Neonatology, School of Medicine, Dokuz Eylul University , Izmir , Turkey
| |
Collapse
|
16
|
von Bernhardi R, Heredia F, Salgado N, Muñoz P. Microglia Function in the Normal Brain. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 949:67-92. [PMID: 27714685 DOI: 10.1007/978-3-319-40764-7_4] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The activation of microglia has been recognized for over a century by their morphological changes. Long slender microglia acquire a short sturdy ramified shape when activated. During the past 20 years, microglia have been accepted as an essential cellular component for understanding the pathogenic mechanism of many brain diseases, including neurodegenerative diseases. More recently, functional studies and imaging in mouse models indicate that microglia are active in the healthy central nervous system. It has become evident that microglia release several signal molecules that play key roles in the crosstalk among brain cells, i.e., astrocytes and oligodendrocytes with neurons, as well as with regulatory immune cells. Recent studies also reveal the heterogeneous nature of microglia diverse functions depending on development, previous exposure to stimulation events, brain region of residence, or pathological state. Subjects to approach by future research are still the unresolved questions regarding the conditions and mechanisms that render microglia protective, capable of preventing or reducing damage, or deleterious, capable of inducing or facilitating the progression of neuropathological diseases. This novel knowledge will certainly change our view on microglia as therapeutic target, shifting our goal from their general silencing to the generation of treatments able to change their activation pattern.
Collapse
Affiliation(s)
- Rommy von Bernhardi
- Escuela de Medicina. Departamento de Neurología, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile.
| | - Florencia Heredia
- Escuela de Medicina. Departamento de Neurología, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Nicole Salgado
- Escuela de Medicina. Departamento de Neurología, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Paola Muñoz
- Escuela de Medicina. Departamento de Neurología, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| |
Collapse
|
17
|
Mosca TJ. On the Teneurin track: a new synaptic organization molecule emerges. Front Cell Neurosci 2015; 9:204. [PMID: 26074772 PMCID: PMC4444827 DOI: 10.3389/fncel.2015.00204] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 05/11/2015] [Indexed: 11/16/2022] Open
Abstract
To achieve proper synaptic development and function, coordinated signals must pass between the pre- and postsynaptic membranes. Such transsynaptic signals can be comprised of receptors and secreted ligands, membrane associated receptors, and also pairs of synaptic cell adhesion molecules. A critical open question bridging neuroscience, developmental biology, and cell biology involves identifying those signals and elucidating how they function. Recent work in Drosophila and vertebrate systems has implicated a family of proteins, the Teneurins, as a new transsynaptic signal in both the peripheral and central nervous systems. The Teneurins have established roles in neuronal wiring, but studies now show their involvement in regulating synaptic connections between neurons and bridging the synaptic membrane and the cytoskeleton. This review will examine the Teneurins as synaptic cell adhesion molecules, explore how they regulate synaptic organization, and consider how some consequences of human Teneurin mutations may have synaptopathic origins.
Collapse
Affiliation(s)
- Timothy J Mosca
- Department of Biology, Stanford University Stanford, CA, USA
| |
Collapse
|
18
|
Soto-Pantoja DR, Kaur S, Roberts DD. CD47 signaling pathways controlling cellular differentiation and responses to stress. Crit Rev Biochem Mol Biol 2015; 50:212-30. [PMID: 25708195 DOI: 10.3109/10409238.2015.1014024] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CD47 is a widely expressed integral membrane protein that serves as the counter-receptor for the inhibitory phagocyte receptor signal-regulatory protein-α (SIRPα) and as a signaling receptor for the secreted matricellular protein thrombospondin-1. Recent studies employing mice and somatic cells lacking CD47 have revealed important pathophysiological functions of CD47 in cardiovascular homeostasis, immune regulation, resistance of cells and tissues to stress and chronic diseases of aging including cancer. With the emergence of experimental therapeutics targeting CD47, a more thorough understanding of CD47 signal transduction is essential. CD47 lacks a substantial cytoplasmic signaling domain, but several cytoplasmic binding partners have been identified, and lateral interactions of CD47 with other membrane receptors play important roles in mediating signaling resulting from the binding of thrombospondin-1. This review addresses recent advances in identifying the lateral binding partners, signal transduction pathways and downstream transcription networks regulated through CD47 in specific cell lineages. Major pathways regulated by CD47 signaling include calcium homeostasis, cyclic nucleotide signaling, nitric oxide and hydrogen sulfide biosynthesis and signaling and stem cell transcription factors. These pathways and other undefined proximal mediators of CD47 signaling regulate cell death and protective autophagy responses, mitochondrial biogenesis, cell adhesion and motility and stem cell self-renewal. Although thrombospondin-1 is the best characterized agonist of CD47, the potential roles of other members of the thrombospondin family, SIRPα and SIRPγ binding and homotypic CD47 interactions as agonists or antagonists of signaling through CD47 should also be considered.
Collapse
Affiliation(s)
- David R Soto-Pantoja
- a Laboratory of Pathology , Center for Cancer Research, National Cancer Institute, National Institutes of Health , Bethesda , MD , USA
| | | | | |
Collapse
|
19
|
Terauchi A, Timmons KM, Kikuma K, Pechmann Y, Kneussel M, Umemori H. Selective synaptic targeting of the excitatory and inhibitory presynaptic organizers FGF22 and FGF7. J Cell Sci 2014; 128:281-92. [PMID: 25431136 DOI: 10.1242/jcs.158337] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Specific formation of excitatory and inhibitory synapses is crucial for proper functioning of the brain. Fibroblast growth factor 22 (FGF22) and FGF7 are postsynaptic-cell-derived presynaptic organizers necessary for excitatory and inhibitory presynaptic differentiation, respectively, in the hippocampus. For the establishment of specific synaptic networks, these FGFs must localize to appropriate synaptic locations - FGF22 to excitatory and FGF7 to inhibitory postsynaptic sites. Here, we show that distinct motor and adaptor proteins contribute to intracellular microtubule transport of FGF22 and FGF7. Excitatory synaptic targeting of FGF22 requires the motor proteins KIF3A and KIF17 and the adaptor protein SAP102 (also known as DLG3). By contrast, inhibitory synaptic targeting of FGF7 requires the motor KIF5 and the adaptor gephyrin. Time-lapse imaging shows that FGF22 moves with SAP102, whereas FGF7 moves with gephyrin. These results reveal the basis of selective targeting of the excitatory and inhibitory presynaptic organizers that supports their different synaptogenic functions. Finally, we found that knockdown of SAP102 or PSD95 (also known as DLG4), which impairs the differentiation of excitatory synapses, alters FGF7 localization, suggesting that signals from excitatory synapses might regulate inhibitory synapse formation by controlling the distribution of the inhibitory presynaptic organizer.
Collapse
Affiliation(s)
- Akiko Terauchi
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA Molecular & Behavioral Neuroscience Institute, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Kendall M Timmons
- Molecular & Behavioral Neuroscience Institute, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Koto Kikuma
- Molecular & Behavioral Neuroscience Institute, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Yvonne Pechmann
- Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Falkenried 94, D-20251 Hamburg, Germany
| | - Matthias Kneussel
- Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Falkenried 94, D-20251 Hamburg, Germany
| | - Hisashi Umemori
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA Molecular & Behavioral Neuroscience Institute, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| |
Collapse
|
20
|
Darabid H, Perez-Gonzalez AP, Robitaille R. Neuromuscular synaptogenesis: coordinating partners with multiple functions. Nat Rev Neurosci 2014; 15:630-1. [DOI: 10.1038/nrn3821] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
21
|
Barclay AN, van den Berg TK. The Interaction Between Signal Regulatory Protein Alpha (SIRPα) and CD47: Structure, Function, and Therapeutic Target. Annu Rev Immunol 2014; 32:25-50. [DOI: 10.1146/annurev-immunol-032713-120142] [Citation(s) in RCA: 448] [Impact Index Per Article: 44.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- A. Neil Barclay
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK;
| | - Timo K. van den Berg
- Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, 1066 CX Amsterdam, The Netherlands;
| |
Collapse
|
22
|
Biederer T. Synaptic uSIRPation: the active neuron reigns over presynaptic partners. Nat Neurosci 2013; 16:1361-2. [PMID: 24067286 DOI: 10.1038/nn.3523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Thomas Biederer
- Department of Molecular Biophysics and Biochemistry and Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University, New Haven, Connecticut, USA
| |
Collapse
|
23
|
Toth AB, Terauchi A, Zhang LY, Johnson-Venkatesh EM, Larsen DJ, Sutton MA, Umemori H. Synapse maturation by activity-dependent ectodomain shedding of SIRPα. Nat Neurosci 2013; 16:1417-25. [PMID: 24036914 PMCID: PMC3820962 DOI: 10.1038/nn.3516] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 08/13/2013] [Indexed: 01/11/2023]
Abstract
Formation of appropriate synaptic connections is critical for proper functioning of the brain. After initial synaptic differentiation, active synapses are stabilized by neural activity-dependent signals to establish functional synaptic connections. However, the molecular mechanisms underlying activity-dependent synapse maturation remain to be elucidated. Here we show that activity-dependent ectodomain shedding of SIRPα mediates presynaptic maturation. Two target-derived molecules, FGF22 and SIRPα, sequentially organize the glutamatergic presynaptic terminals during the initial synaptic differentiation and synapse maturation stages, respectively, in the mouse hippocampus. SIRPα drives presynaptic maturation in an activity-dependent fashion. Remarkably, neural activity cleaves the extracellular domain of SIRPα, and the shed ectodomain, in turn, promotes the maturation of the presynaptic terminal. This process involves CaM kinase, matrix metalloproteinases, and the presynaptic receptor CD47. Finally, SIRPα-dependent synapse maturation has significant impacts on synaptic function and plasticity. Thus, ectodomain shedding of SIRPα is an activity-dependent trans-synaptic mechanism for the maturation of functional synapses.
Collapse
Affiliation(s)
- Anna B Toth
- 1] Molecular & Behavioral Neuroscience Institute, University of Michigan Medical School, Ann Arbor, Michigan, USA. [2]
| | | | | | | | | | | | | |
Collapse
|
24
|
Bicchi I, Morena F, Montesano S, Polidoro M, Martino S. MicroRNAs and Molecular Mechanisms of Neurodegeneration. Genes (Basel) 2013; 4:244-63. [PMID: 24705162 PMCID: PMC3899972 DOI: 10.3390/genes4020244] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 05/09/2013] [Accepted: 05/10/2013] [Indexed: 12/21/2022] Open
Abstract
During the last few years microRNAs (miRNAs) have emerged as key mediators of post-transcriptional and epigenetic regulation of gene expression. MiRNAs targets, identified through gene expression profiling and studies in animal models, depict a scenario where miRNAs are fine-tuning metabolic pathways and genetic networks in both plants and animals. MiRNAs have shown to be differentially expressed in brain areas and alterations of miRNAs homeostasis have been recently correlated to pathological conditions of the nervous system, such as cancer and neurodegeneration. Here, we review and discuss the most recent insights into the involvement of miRNAs in the neurodegenerative mechanisms and their correlation with significant neurodegenerative disorders.
Collapse
Affiliation(s)
- Ilaria Bicchi
- Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Via del Giochetto, 06126 Perugia, Italy.
| | - Francesco Morena
- Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Via del Giochetto, 06126 Perugia, Italy.
| | - Simona Montesano
- Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Via del Giochetto, 06126 Perugia, Italy.
| | - Mario Polidoro
- Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Via del Giochetto, 06126 Perugia, Italy.
| | - Sabata Martino
- Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Via del Giochetto, 06126 Perugia, Italy.
| |
Collapse
|
25
|
Abstract
Compelling evidence from in vivo model systems within the past decade shows that the APP family of proteins is important for synaptic development and function in the central and peripheral nervous systems. The synaptic role promises to be complex and multifaceted for several reasons. The three family members have overlapping and redundant functions in mammals. They have both adhesive and signaling properties and may, in principle, act as both ligands and receptors. Moreover, they bind a multitude of synapse-specific proteins, and we predict that additional interacting protein partners will be discovered. Transgenic mice with modified or abolished expression of APP and APLPs have synaptic defects that are readily apparent. Studies of the neuromuscular junction (NMJ) in these transgenic mice have revealed molecular and functional deficits in neurotransmitter release, in organization of the postsynaptic receptors, and in coordinated intercellular development. The results summarized here from invertebrate and vertebrate systems confirm that the NMJ with its accessibility, large size, and homogeneity provides a model synapse for identifying and analyzing molecular pathways of APP actions.
Collapse
|
26
|
Wu H, Lu Y, Shen C, Patel N, Gan L, Xiong WC, Mei L. Distinct roles of muscle and motoneuron LRP4 in neuromuscular junction formation. Neuron 2012; 75:94-107. [PMID: 22794264 DOI: 10.1016/j.neuron.2012.04.033] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/23/2012] [Indexed: 01/07/2023]
Abstract
Neuromuscular junction (NMJ) formation requires precise interaction between motoneurons and muscle fibers. LRP4 is a receptor of agrin that is thought to act in cis to stimulate MuSK in muscle fibers for postsynaptic differentiation. Here we dissected the roles of LRP4 in muscle fibers and motoneurons in NMJ formation by cell-specific mutation. Studies of muscle-specific mutants suggest that LRP4 is involved in deciding where to form AChR clusters in muscle fibers, postsynaptic differentiation, and axon terminal development. LRP4 in HEK293 cells increased synapsin or SV2 puncta in contacting axons of cocultured neurons, suggesting a synaptogenic function. Analysis of LRP4 muscle and motoneuron double mutants and mechanistic studies suggest that NMJ formation may also be regulated by LRP4 in motoneurons, which could serve as agrin's receptor in trans to induce AChR clusters. These observations uncovered distinct roles of LRP4 in motoneurons and muscles in NMJ development.
Collapse
Affiliation(s)
- Haitao Wu
- Institute of Molecular Medicine and Genetics and Department of Neurology, Medical College of Georgia, Georgia Health Sciences University, Augusta, GA 30912, USA
| | | | | | | | | | | | | |
Collapse
|
27
|
Marschinke F, Hashemian S, Matozaki T, Oldenborg PA, Strömberg I. The absence of CD47 promotes nerve fiber growth from cultured ventral mesencephalic dopamine neurons. PLoS One 2012; 7:e45218. [PMID: 23049778 PMCID: PMC3458886 DOI: 10.1371/journal.pone.0045218] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 08/14/2012] [Indexed: 11/19/2022] Open
Abstract
In ventral mesencephalic organotypic tissue cultures, two timely separated sequences of nerve fiber growth have been observed. The first appearing nerve fiber pattern is a long-distance outgrowth that occurs before astrocytes start to proliferate and migrate to form an astrocytic monolayer that finally surrounds the tissue slice. These long-distance growing nerve fibers are retracted as the astrocytes migrate, and are followed by a secondary outgrowth. The secondary outgrowth is persistent in time but reaches short distances, comparable with outgrowth seen from a dopaminergic graft implanted to the brain. The present study was focused on the interaction between the astrocytes and the long-distance growing non-glial associated nerve fibers. Cross talk between astroglia and neurite formation might occur through the integrin-associated protein CD47. CD47 serves as a ligand for signal regulatory protein (SIRP) α and as a receptor for the extracellular matrix protein thrombospondin-1 (TSP-1). Embryonic day 14 ventral mesencephalic tissue from CD47+/+ and CD47−/− mice was used to investigate astrocytic migration and the tyrosine hydroxylase (TH) –positive outgrowth that occurred remote from the astrocytes. TH-immunohistochemistry demonstrated that the non-glial-associated nerve fiber outgrowth in CD47−/− cultures reached significantly longer distances and higher density compared to nerve fibers formed in CD47+/+ cultures at 14 days in vitro. These nerve fibers often had a dotted appearance in CD47+/+ cultures. No difference in the astrocytic migration was observed. Further investigations revealed that the presence of CD47 in control culture did neither hamper non-glial-associated growth through SIRPα nor through TSP-1 since similar outgrowth was found in SIRPα mutant cultures and in CD47+/+ cultures treated with blocking antibodies against the TSP-1, respectively, as in the control cultures. In conclusion, long-distance growing nerve fiber formation is promoted by the absence of CD47, even though the presence of astrocytes is not inhibited.
Collapse
Affiliation(s)
| | - Sanaz Hashemian
- Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
| | - Takashi Matozaki
- Division of Molecular and Cellular Signaling, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Per-Arne Oldenborg
- Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
| | - Ingrid Strömberg
- Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
- * E-mail:
| |
Collapse
|
28
|
Lrp4 is a retrograde signal for presynaptic differentiation at neuromuscular synapses. Nature 2012; 489:438-42. [PMID: 22854782 PMCID: PMC3448831 DOI: 10.1038/nature11348] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 06/22/2012] [Indexed: 01/28/2023]
Abstract
Motor axons receive retrograde signals from skeletal muscle that are essential for the differentiation and stabilization of motor nerve terminals 1. Identification of these retrograde signals has proved elusive, but their production by muscle depends upon the receptor tyrosine kinase, MuSK, and Lrp4, a LDLR family member that forms a complex with MuSK, binds neural Agrin and stimulates MuSK kinase activity 2–5. Here, we show that Lrp4 also functions as a direct muscle-derived retrograde signal for early steps in presynaptic differentiation. We demonstrate that Lrp4 is necessary, independent of MuSK activation, for presynaptic differentiation in vivo, and we show that Lrp4 binds to motor axons and induces clustering of synaptic vesicle and active zone proteins. Thus, Lrp4 acts bi-directionally and coordinates synapse formation by binding Agrin, activating MuSK and stimulating postsynaptic differentiation and in turn functioning as a muscle-derived retrograde signal that is necessary and sufficient for presynaptic differentiation.
Collapse
|
29
|
Abstract
Microglial cells are the resident macrophages in the central nervous system. These cells of mesodermal/mesenchymal origin migrate into all regions of the central nervous system, disseminate through the brain parenchyma, and acquire a specific ramified morphological phenotype termed "resting microglia." Recent studies indicate that even in the normal brain, microglia have highly motile processes by which they scan their territorial domains. By a large number of signaling pathways they can communicate with macroglial cells and neurons and with cells of the immune system. Likewise, microglial cells express receptors classically described for brain-specific communication such as neurotransmitter receptors and those first discovered as immune cell-specific such as for cytokines. Microglial cells are considered the most susceptible sensors of brain pathology. Upon any detection of signs for brain lesions or nervous system dysfunction, microglial cells undergo a complex, multistage activation process that converts them into the "activated microglial cell." This cell form has the capacity to release a large number of substances that can act detrimental or beneficial for the surrounding cells. Activated microglial cells can migrate to the site of injury, proliferate, and phagocytose cells and cellular compartments.
Collapse
|
30
|
Dabrowski A, Umemori H. Orchestrating the synaptic network by tyrosine phosphorylation signalling. J Biochem 2011; 149:641-53. [PMID: 21508038 PMCID: PMC3143439 DOI: 10.1093/jb/mvr047] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2011] [Accepted: 04/08/2011] [Indexed: 01/07/2023] Open
Abstract
The establishment of a functional brain requires coordinated and stereotyped formation of synapses between neurons. For this, trans-synaptic molecular cues (synaptic organizers) are exchanged between a neuron and its target to organize appropriate synapses. The understanding of signalling mechanisms by which such synaptic organizers lead to synapse formation is just being elucidated. However, recent studies revealed that some of these cues act through receptor protein tyrosine kinases (RPTKs) or phosphatases (RPTPs). Synaptogenic RPTKs and RPTPs pattern synaptic network through affecting local protein-protein binding dynamics, changing the phosphorylation state of signalling cascades, or promoting gene expression. Each RPTK or RPTP has distinct roles in synapse formation, serving at different synapses or showing differential synaptogenic effects. Thus, tyrosine phosphorylation signalling plays critical roles in building the orchestrated synaptic circuitry in the brain.
Collapse
Affiliation(s)
- Ania Dabrowski
- Molecular & Behavioral Neuroscience Institute, Medical Scientist Training Program, Neuroscience Graduate Program and Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Hisashi Umemori
- Molecular & Behavioral Neuroscience Institute, Medical Scientist Training Program, Neuroscience Graduate Program and Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| |
Collapse
|
31
|
Siddiqui TJ, Craig AM. Synaptic organizing complexes. Curr Opin Neurobiol 2010; 21:132-43. [PMID: 20832286 DOI: 10.1016/j.conb.2010.08.016] [Citation(s) in RCA: 210] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 08/09/2010] [Accepted: 08/14/2010] [Indexed: 01/01/2023]
Abstract
A number of synaptogenic factors induce presynaptic or postsynaptic differentiation when presented to axons or dendrites. Many such factors participate in bidirectional trans-synaptic adhesion complexes. Axonal neurexins interacting in an isoform-specific code with multiple dendritic partners (neuroligins, LRRTMs, or Cbln-GluRδ), and axonal protein tyrosine phosphatase receptors interacting with dendritic NGL-3, nucleate local networks of high-affinity protein-protein interactions leading to aligned presynaptic and postsynaptic differentiation. Additional secreted target-derived factors such as fibroblast growth factors and glial-derived factors such as thrombospondin bind specific axonal or dendritic receptors stimulating signal transduction mechanisms to promote selective aspects of synapse development. Together with classical adhesion molecules and controlled by transcriptional cascades, these synaptogenic adhesion complexes and secreted factors organize the molecular composition and thus functional properties of central synapses.
Collapse
Affiliation(s)
- Tabrez J Siddiqui
- Brain Research Centre and Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada V6T 2B5
| | | |
Collapse
|
32
|
Lee WY, Weber DA, Laur O, Stowell SR, McCall I, Andargachew R, Cummings RD, Parkos CA. The role of cis dimerization of signal regulatory protein alpha (SIRPalpha) in binding to CD47. J Biol Chem 2010; 285:37953-63. [PMID: 20826801 DOI: 10.1074/jbc.m110.180018] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Interaction of SIRPα with its ligand, CD47, regulates leukocyte functions, including transmigration, phagocytosis, oxidative burst, and cytokine secretion. Recent progress has provided significant insights into the structural details of the distal IgV domain (D1) of SIRPα. However, the structural roles of proximal IgC domains (D2 and D3) have been largely unstudied. The high degree of conservation of D2 and D3 among members of the SIRP family as well as the propensity of known IgC domains to assemble in cis has led others to hypothesize that SIRPα forms higher order structures on the cell surface. Here we report that SIRPα forms noncovalently linked cis homodimers. Treatment of SIRPα-expressing cells with a membrane-impermeable cross-linker resulted in the formation of SDS-stable SIRPα dimers and oligomers. Biochemical analyses of soluble recombinant extracellular regions of SIRPα, including domain truncation mutants, revealed that each of the three extracellular immunoglobulin loops of SIRPα formed dimers in solution. Co-immunoprecipitation experiments using cells transfected with different affinity-tagged SIRPα molecules revealed that SIRPα forms cis dimers. Interestingly, in cells treated with tunicamycin, SIRPα dimerization but not CD47 binding was inhibited, suggesting that a SIRPα dimer is probably bivalent. Last, we demonstrate robust dimerization of SIRPa in adherent, stimulated human neutrophils. Collectively, these data are consistent with SIRPα being expressed on the cell surface as a functional cis-linked dimer.
Collapse
Affiliation(s)
- Winston Y Lee
- Epithelial Pathobiology Unit, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | | | | | | | | | | | | | | |
Collapse
|
33
|
Jones K, Basson MA. FGF ligands emerge as potential specifiers of synaptic identity. CELLSCIENCE 2010; 7:33-42. [PMID: 20890457 PMCID: PMC2948530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The central nervous system (CNS) consists of trillions of interconnected neurons. The specialised regions of intercellular contact between neurons where information, usually in chemical form, is transmitted are called synapses. The last decade has seen an unprecedented advance in our understanding of the molecular nature, formation and maintenance of synapses. A major question that remains is how synaptic identity is established to ensure the coordinated recruitment of the correct synaptic components on both sides of the synapse so that the neurotransmitter accumulating on the presynaptic side is matched with its cognate receptor on the postsynaptic membrane. Until recently, Fibroblast Growth Factors (FGFs) have been thought of as general regulators of synaptic aptitude through their ability to increase the expression of synaptic proteins or promote neurite branching. A recent study shows that the decision to form an excitatory vs. inhibitory synapse may to a large extent be determined by the identity of the FGF ligand present at the postsynaptic membrane. This observation establishes FGFs as key target-derived cues that are involved in determining synaptic identity.
Collapse
Affiliation(s)
- Kieran Jones
- King's College London, Department of Craniofacial Development and MRC Centre for Developmental Neurobiology, Floor 27, Guy's Tower, London SE1 9RT, UK
| | | |
Collapse
|
34
|
Abstract
A critical step in synaptic development is the differentiation of presynaptic and postsynaptic compartments. This complex process is regulated by a variety of secreted factors that serve as synaptic organizers. Specifically, fibroblast growth factors, Wnts, neurotrophic factors and various other intercellular signaling molecules are proposed to regulate presynaptic and/or postsynaptic differentiation. Many of these factors appear to function at both the neuromuscular junction and in the central nervous system, although the specific function of the molecules differs between the two. Here we review secreted molecules that organize the synaptic compartments and discuss how these molecules shape synaptic development, focusing on mammalian in vivo systems. Their critical role in shaping a functional neural circuit is underscored by their possible link to a wide range of neurological and psychiatric disorders both in animal models and by mutations identified in human patients.
Collapse
Affiliation(s)
- Erin M Johnson-Venkatesh
- Molecular & Behavioral Neuroscience Institute, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | | |
Collapse
|
35
|
Terauchi A, Johnson-Venkatesh EM, Toth AB, Javed D, Sutton MA, Umemori H. Distinct FGFs promote differentiation of excitatory and inhibitory synapses. Nature 2010; 465:783-7. [PMID: 20505669 DOI: 10.1038/nature09041] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Accepted: 03/19/2010] [Indexed: 02/06/2023]
Abstract
The differential formation of excitatory (glutamate-mediated) and inhibitory (GABA-mediated) synapses is a critical step for the proper functioning of the brain. An imbalance in these synapses may lead to various neurological disorders such as autism, schizophrenia, Tourette's syndrome and epilepsy. Synapses are formed through communication between the appropriate synaptic partners. However, the molecular mechanisms that mediate the formation of specific synaptic types are not known. Here we show that two members of the fibroblast growth factor (FGF) family, FGF22 and FGF7, promote the organization of excitatory and inhibitory presynaptic terminals, respectively, as target-derived presynaptic organizers. FGF22 and FGF7 are expressed by CA3 pyramidal neurons in the hippocampus. The differentiation of excitatory or inhibitory nerve terminals on dendrites of CA3 pyramidal neurons is specifically impaired in mutants lacking FGF22 or FGF7. These presynaptic defects are rescued by postsynaptic expression of the appropriate FGF. FGF22-deficient mice are resistant to epileptic seizures, and FGF7-deficient mice are prone to them, as expected from the alterations in excitatory/inhibitory balance. Differential effects of FGF22 and FGF7 involve both their distinct synaptic localizations and their use of different signalling pathways. These results demonstrate that specific FGFs act as target-derived presynaptic organizers and help to organize specific presynaptic terminals in the mammalian brain.
Collapse
Affiliation(s)
- Akiko Terauchi
- Molecular and Behavioral Neuroscience Institute, University of Michigan Medical School, Ann Arbor, Michigan 48109-2200, USA
| | | | | | | | | | | |
Collapse
|
36
|
Synaptic localization and function of Sidekick recognition molecules require MAGI scaffolding proteins. J Neurosci 2010; 30:3579-88. [PMID: 20219992 DOI: 10.1523/jneurosci.6319-09.2010] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Four transmembrane adhesion molecules-Sidekick-1, Sidekick-2, Down's syndrome cell adhesion molecule (Dscam), and Dscam-like-are determinants of lamina-specific synapse formation in the vertebrate retina. Their C termini are predicted to bind postsynaptic density (PSD)-95/Discs Large/ZO-1 (PDZ) domains, which are present in many synaptic scaffolding proteins. We identify members of the membrane-associated guanylate kinase with inverted orientation (MAGI) and PSD-95 subfamilies of multi-PDZ domain proteins as binding partners for Sidekicks and Dscams. Specific MAGI and PSD-95 family members are present in distinct subsets of retinal synapses, as are Sidekicks and Dscams. Using Sidekick-2 as an exemplar, we show that its PDZ-binding C terminus is required for both its synaptic localization in photoreceptors and its ability to promote lamina-specific arborization of presynaptic and postsynaptic processes in the inner plexiform layer. In photoreceptor synapses that contain both MAGI-1 and PSD-95, Sidekick-2 preferentially associates with MAGI-1. Depletion of MAGI-1 from photoreceptors by RNA interference blocks synaptic localization of Sidekick-2 in photoreceptors without affecting localization of PSD-95. Likewise, depletion of MAGI-2 from retinal ganglion cells and interneurons interferes with Sidekick-2-dependent laminar targeting of processes. These results demonstrate that localization and function of Sidekick-2 require its incorporation into a MAGI-containing synaptic scaffold.
Collapse
|
37
|
Wu H, Xiong WC, Mei L. To build a synapse: signaling pathways in neuromuscular junction assembly. Development 2010; 137:1017-33. [PMID: 20215342 DOI: 10.1242/dev.038711] [Citation(s) in RCA: 379] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Synapses, as fundamental units of the neural circuitry, enable complex behaviors. The neuromuscular junction (NMJ) is a synapse type that forms between motoneurons and skeletal muscle fibers and that exhibits a high degree of subcellular specialization. Aided by genetic techniques and suitable animal models, studies in the past decade have brought significant progress in identifying NMJ components and assembly mechanisms. This review highlights recent advances in the study of NMJ development, focusing on signaling pathways that are activated by diffusible cues, which shed light on synaptogenesis in the brain and contribute to a better understanding of muscular dystrophy.
Collapse
Affiliation(s)
- Haitao Wu
- Program of Developmental Neurobiology, Institute of Molecular Medicine and Genetics, Department of Neurology, Medical College of Georgia, Augusta, GA 30912, USA
| | | | | |
Collapse
|
38
|
Su J, Gorse K, Ramirez F, Fox MA. Collagen XIX is expressed by interneurons and contributes to the formation of hippocampal synapses. J Comp Neurol 2010; 518:229-53. [PMID: 19937713 DOI: 10.1002/cne.22228] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Extracellular matrix (ECM) molecules contribute to the formation and maintenance of synapses in the mammalian nervous system. We previously discovered a family of nonfibrillar collagens that organize synaptic differentiation at the neuromuscular junction (NMJ). Although many NMJ-organizing cues contribute to central nervous system (CNS) synaptogenesis, whether similar roles for collagens exist at central synapses remained unclear. In the present study we discovered that col19a1, the gene encoding nonfibrillar collagen XIX, is expressed by subsets of hippocampal neurons. Colocalization with the interneuron-specific enzyme glutamate decarboxylase 67 (Gad67), but not other cell-type-specific markers, suggests that hippocampal expression of col19a1 is restricted to interneurons. However, not all hippocampal interneurons express col19a1 mRNA; subsets of neuropeptide Y (NPY)-, somatostatin (Som)-, and calbindin (Calb)-immunoreactive interneurons express col19a1, but those containing parvalbumin (Parv) or calretinin (Calr) do not. To assess whether collagen XIX is required for the normal formation of hippocampal synapses, we examined synaptic morphology and composition in targeted mouse mutants lacking collagen XIX. We show here that subsets of synaptotagmin 2 (Syt2)-containing hippocampal nerve terminals appear malformed in the absence of collagen XIX. The presence of Syt2 in inhibitory hippocampal synapses, the altered distribution of Gad67 in collagen XIX-deficient subiculum, and abnormal levels of gephyrin in collagen XIX-deficient hippocampal extracts all suggest inhibitory synapses are affected by the loss of collagen XIX. Together, these data not only reveal that collagen XIX is expressed by central neurons, but show for the first time that a nonfibrillar collagen is necessary for the formation of hippocampal synapses.
Collapse
Affiliation(s)
- Jianmin Su
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, Virginia 23298, USA
| | | | | | | |
Collapse
|
39
|
Williams AH, Valdez G, Moresi V, Qi X, McAnally J, Elliott JL, Bassel-Duby R, Sanes JR, Olson EN. MicroRNA-206 delays ALS progression and promotes regeneration of neuromuscular synapses in mice. Science 2009; 326:1549-54. [PMID: 20007902 PMCID: PMC2796560 DOI: 10.1126/science.1181046] [Citation(s) in RCA: 569] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by loss of motor neurons, denervation of target muscles, muscle atrophy, and paralysis. Understanding ALS pathogenesis may require a fuller understanding of the bidirectional signaling between motor neurons and skeletal muscle fibers at neuromuscular synapses. Here, we show that a key regulator of this signaling is miR-206, a skeletal muscle-specific microRNA that is dramatically induced in a mouse model of ALS. Mice that are genetically deficient in miR-206 form normal neuromuscular synapses during development, but deficiency of miR-206 in the ALS mouse model accelerates disease progression. miR-206 is required for efficient regeneration of neuromuscular synapses after acute nerve injury, which probably accounts for its salutary effects in ALS. miR-206 mediates these effects at least in part through histone deacetylase 4 and fibroblast growth factor signaling pathways. Thus, miR-206 slows ALS progression by sensing motor neuron injury and promoting the compensatory regeneration of neuromuscular synapses.
Collapse
Affiliation(s)
- Andrew H. Williams
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| | - Gregorio Valdez
- Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, Massachusetts, 02138, USA
| | - Viviana Moresi
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| | - Xiaoxia Qi
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| | - John McAnally
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| | - Jeffrey L. Elliott
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| | - Rhonda Bassel-Duby
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| | - Joshua R. Sanes
- Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, Massachusetts, 02138, USA
| | - Eric N. Olson
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| |
Collapse
|
40
|
Barclay AN. Signal regulatory protein alpha (SIRPalpha)/CD47 interaction and function. Curr Opin Immunol 2009; 21:47-52. [PMID: 19223164 PMCID: PMC3128989 DOI: 10.1016/j.coi.2009.01.008] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Accepted: 01/20/2009] [Indexed: 12/12/2022]
Abstract
SIRPalpha is an inhibitory receptor present on myeloid cells that interacts with a widely distributed membrane protein CD47. The activating member SIRPbeta, despite extensive sequence similarity to SIRPalpha in the extracellular region, shows negligible binding to CD47. The SIRPalpha/CD47 interaction is unusual in that it can lead to bidirectional signalling through both SIRPalpha and CD47. This review concentrates on the interactions of SIRPalpha with CD47 where recent data have shed light on the structure of the proteins including determining why the activating SIRPbeta does not bind CD47, evidence of extensive polymorphisms and implication for the evolution and function of this protein and paired receptors in general. The interaction may be modified by endocytosis of the receptors, cleavage by proteolysis and through interactions of surfactant proteins.
Collapse
Affiliation(s)
- A Neil Barclay
- Sir William Dunn School of Pathology, University of Oxford, United Kingdom.
| |
Collapse
|
41
|
Tian L, Rauvala H, Gahmberg CG. Neuronal regulation of immune responses in the central nervous system. Trends Immunol 2009; 30:91-9. [PMID: 19144568 DOI: 10.1016/j.it.2008.11.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 11/21/2008] [Accepted: 11/21/2008] [Indexed: 10/21/2022]
Abstract
The central nervous system (CNS) has traditionally been considered to be immunologically privileged, but over the years there has been a re-evaluation of this dogma. To date, studies have tended to focus on the immune functions of glial cells, whereas the roles of neurons have been regarded as passive and their immune-regulatory properties have been less examined. However, recent findings indicate that CNS neurons actively participate in immune regulation by controlling their glial cell counterparts and infiltrated T cells. Here, we describe the immune-regulatory roles of CNS neurons by both contact-dependent and contact-independent mechanisms. In addition, we specifically deal with the immune functions of neuronal cell adhesion molecules, many of which are key modulators of neuronal synaptic formation and plasticity.
Collapse
Affiliation(s)
- Li Tian
- Neuroscience Center, University of Helsinki, Viikinkaari 4, FIN-00014, Helsinki, Finland.
| | | | | |
Collapse
|