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Mah KM, Weiner JA. Regulation of Wnt signaling by protocadherins. Semin Cell Dev Biol 2017; 69:158-171. [PMID: 28774578 PMCID: PMC5586504 DOI: 10.1016/j.semcdb.2017.07.043] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 07/21/2017] [Accepted: 07/28/2017] [Indexed: 12/23/2022]
Abstract
The ∼70 protocadherins comprise the largest group within the cadherin superfamily. Their diversity, the complexity of the mechanisms through which their genes are regulated, and their many critical functions in nervous system development have engendered a growing interest in elucidating the intracellular signaling pathways through which they act. Recently, multiple protocadherins across several subfamilies have been implicated as modulators of Wnt signaling pathways, and through this as potential tumor suppressors. Here, we review the extant data on the regulation by protocadherins of Wnt signaling pathways and components, and highlight some key unanswered questions that could shape future research.
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Affiliation(s)
- Kar Men Mah
- Department of Biology, The University of Iowa, Iowa City, IA, USA.
| | - Joshua A Weiner
- Department of Biology, The University of Iowa, Iowa City, IA, USA; Department of Psychiatry, The University of Iowa, Iowa City, IA, USA; Iowa Neuroscience Institute, The University of Iowa, Iowa City, IA, USA.
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52
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Elegheert J, Cvetkovska V, Clayton AJ, Heroven C, Vennekens KM, Smukowski SN, Regan MC, Jia W, Smith AC, Furukawa H, Savas JN, de Wit J, Begbie J, Craig AM, Aricescu AR. Structural Mechanism for Modulation of Synaptic Neuroligin-Neurexin Signaling by MDGA Proteins. Neuron 2017; 95:896-913.e10. [PMID: 28817804 PMCID: PMC5563082 DOI: 10.1016/j.neuron.2017.07.040] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Revised: 06/22/2017] [Accepted: 07/28/2017] [Indexed: 01/30/2023]
Abstract
Neuroligin-neurexin (NL-NRX) complexes are fundamental synaptic organizers in the central nervous system. An accurate spatial and temporal control of NL-NRX signaling is crucial to balance excitatory and inhibitory neurotransmission, and perturbations are linked with neurodevelopmental and psychiatric disorders. MDGA proteins bind NLs and control their function and interaction with NRXs via unknown mechanisms. Here, we report crystal structures of MDGA1, the NL1-MDGA1 complex, and a spliced NL1 isoform. Two large, multi-domain MDGA molecules fold into rigid triangular structures, cradling a dimeric NL to prevent NRX binding. Structural analyses guided the discovery of a broad, splicing-modulated interaction network between MDGA and NL family members and helped rationalize the impact of autism-linked mutations. We demonstrate that expression levels largely determine whether MDGAs act selectively or suppress the synapse organizing function of multiple NLs. These results illustrate a potentially brain-wide regulatory mechanism for NL-NRX signaling modulation. The MDGA1 extracellular region has an unusual triangular multi-domain arrangement The NL1-MDGA1 complex structure reveals how MDGA proteins block neurexin binding MDGA1 and MDGA2 bind all NL isoforms, a process fine-tuned by alternative splicing MDGA1 and MDGA2 suppress NL synaptogenic activity in a concentration-dependent manner
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Affiliation(s)
- Jonathan Elegheert
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK.
| | - Vedrana Cvetkovska
- Djavad Mowafaghian Centre for Brain Health and Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Amber J Clayton
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Christina Heroven
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK; MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Kristel M Vennekens
- VIB Center for Brain and Disease Research, Herestraat 49, B-3000 Leuven, Belgium; Department of Neurosciences, KU Leuven, Herestraat 49, B-3000 Leuven, Belgium
| | - Samuel N Smukowski
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Michael C Regan
- Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA
| | - Wanyi Jia
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Alexandra C Smith
- Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
| | - Hiro Furukawa
- Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA
| | - Jeffrey N Savas
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Joris de Wit
- VIB Center for Brain and Disease Research, Herestraat 49, B-3000 Leuven, Belgium; Department of Neurosciences, KU Leuven, Herestraat 49, B-3000 Leuven, Belgium
| | - Jo Begbie
- Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
| | - Ann Marie Craig
- Djavad Mowafaghian Centre for Brain Health and Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 2B5, Canada.
| | - A Radu Aricescu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK; MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.
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Synaptic Adhesion Molecule Pcdh-γC5 Mediates Synaptic Dysfunction in Alzheimer's Disease. J Neurosci 2017; 37:9259-9268. [PMID: 28842416 DOI: 10.1523/jneurosci.1051-17.2017] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 07/22/2017] [Accepted: 08/14/2017] [Indexed: 11/21/2022] Open
Abstract
Synaptic dysfunction and neuronal excitatory/inhibitory imbalance have been implicated in Alzheimer's disease (AD) pathogenesis. Although intensive studies have been focused on the excitatory synaptic system, much less is known concerning the mechanisms mediating inhibitory synaptic dysfunction in AD. We reported previously that protocadherin-γC5 (Pcdh-γC5), a member of clustered Pcdh-γ subfamily of cadherin-type synaptic adhesion proteins, functions to promote GABAergic synaptic transmission. We reveal here that Pcdh-γC5 is enriched in vesicular GABA transporter-positive synaptic puncta and its expression levels are increased in neuronal hyperexcitation conditions, upon β-amyloid (Aβ) treatment, and in amyloid precursor protein (APP)/presenilin-1 (PS1)-transgenic mice of both sexes. This is associated with elevated levels of GABAergic proteins and enhanced synaptic inhibition. Genetic knock-down experiments showed that Pcdh-γC5 modulates spontaneous synaptic currents and Aβ-induced synaptic alterations directly. Our results support a model in which Pcdh-γC5 senses neuronal hyperexcitation to augment GABAergic inhibition. This adaptive mechanism may be dysregulated under chronic excitation conditions such as AD, leading to aberrant Pcdh-γC5 expression and associated synaptic dysfunction.SIGNIFICANCE STATEMENT Synaptic dysfunction is causal for Alzheimer's disease (AD). Here, we reveal a novel pathway that contributes GABAergic synaptic dysfunction in AD mediated by protocadherin-γC5. Our study not only identifies a new mechanism mediating excitatory/inhibitory balance in AD, but may also offer a new target for potential therapeutic intervention.
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Rubinstein R, Goodman KM, Maniatis T, Shapiro L, Honig B. Structural origins of clustered protocadherin-mediated neuronal barcoding. Semin Cell Dev Biol 2017; 69:140-150. [PMID: 28743640 DOI: 10.1016/j.semcdb.2017.07.023] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 07/14/2017] [Accepted: 07/18/2017] [Indexed: 12/20/2022]
Abstract
Clustered protocadherins mediate neuronal self-recognition and non-self discrimination-neuronal "barcoding"-which underpin neuronal self-avoidance in vertebrate neurons. Recent structural, biophysical, computational, and cell-based studies on protocadherin structure and function have led to a compelling molecular model for the barcoding mechanism. Protocadherin isoforms assemble into promiscuous cis-dimeric recognition units and mediate cell-cell recognition through homophilic trans-interactions. Each recognition unit is composed of two arms extending from the membrane proximal EC6 domains. A cis-dimeric recognition unit with each arm coding adhesive trans homophilic specificity can generate a zipper-like assembly that in turn suggests a chain termination mechanism for self-vs-non-self-discrimination among vertebrate neurons.
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Affiliation(s)
- Rotem Rubinstein
- Department of Biochemistry and Molecular Biophysics, New York, NY 10032, USA; Department of Systems Biology, New York, NY 10032, USA
| | - Kerry Marie Goodman
- Department of Biochemistry and Molecular Biophysics, New York, NY 10032, USA
| | - Tom Maniatis
- Department of Biochemistry and Molecular Biophysics, New York, NY 10032, USA; Zuckerman Mind Brain and Behavior Institute, New York, NY 10032, USA.
| | - Lawrence Shapiro
- Department of Biochemistry and Molecular Biophysics, New York, NY 10032, USA; Zuckerman Mind Brain and Behavior Institute, New York, NY 10032, USA.
| | - Barry Honig
- Department of Biochemistry and Molecular Biophysics, New York, NY 10032, USA; Department of Systems Biology, New York, NY 10032, USA; Zuckerman Mind Brain and Behavior Institute, New York, NY 10032, USA; Howard Hughes Medical Institute, New York, NY 10032, USA; Department of Medicine, Columbia University, New York, NY 10032, USA.
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Epigenetic dysregulation of protocadherins in human disease. Semin Cell Dev Biol 2017; 69:172-182. [PMID: 28694114 DOI: 10.1016/j.semcdb.2017.07.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 07/03/2017] [Accepted: 07/06/2017] [Indexed: 12/12/2022]
Abstract
Protocadherins (Pcdhs) are a group of cell-cell adhesion molecules that are highly expressed in the nervous system and have a major function in dendrite development and neural circuit formation. However, the role protocadherins play in human health and disease remains unclear. Several recent studies have associated epigenetic dysregulation of protocadherins with possible implications for disease pathogenesis. In this review, we briefly recap the various epigenetic mechanisms regulating protocadherin genes, particularly the clustered Pcdhs. We further outline research describing altered epigenetic regulation of protocadherins in neurological and psychiatric disorders, as well as in cancer and during aging. We additionally present preliminary data on DNA methylation dynamics of clustered protocadherins during fetal brain development, as well as the epigenetic differences distinguishing adult neuronal and glial cells. A deeper understanding of the role of protocadherins in disease is crucial for designing novel diagnostic tools and therapies targeting brain disorders.
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Hirayama T, Yagi T. Regulation of clustered protocadherin genes in individual neurons. Semin Cell Dev Biol 2017; 69:122-130. [PMID: 28591566 DOI: 10.1016/j.semcdb.2017.05.026] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 05/16/2017] [Accepted: 05/17/2017] [Indexed: 02/06/2023]
Abstract
Individual neurons are basic functional units in the complex system of the brain. One aspect of neuronal individuality is generated by stochastic and combinatorial expression of diverse clustered protocadherins (Pcdhs), encoded by the Pcdha, Pcdhb, and Pcdhg gene clusters, that are critical for several aspects of neural circuit formation. Each clustered Pcdh gene has its own promoter containing conserved sequences and is transcribed by a promoter choice mechanism involving interaction between the promoter and enhancers. A CTCF/Cohesin complex induces this interaction by configuration of DNA-looping in the chromatin structure. At the same time, the semi-stochastic expression of clustered Pcdh genes is regulated in individual neurons by DNA methylation: the methyltransferase Dnmt3b regulates methylation state of individual clustered Pcdh genes during early embryonic stages prior to the establishment of neural stem cells. Several other factors, including Smchd1, also contribute to the regulation of clustered Pcdh gene expression. In addition, psychiatric diseases and early life experiences of individuals can influence expression of clustered Pcdh genes in the brain, through epigenetic alterations. Clustered Pcdh gene expression is thus a significant and highly regulated step in establishing neuronal individuality and generating functional neural circuits in the brain.
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Affiliation(s)
- Teruyoshi Hirayama
- KOKORO-Biology Group, Laboratories for Integrated Biology, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Takeshi Yagi
- KOKORO-Biology Group, Laboratories for Integrated Biology, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
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Phillips GR, LaMassa N, Nie YM. Clustered protocadherin trafficking. Semin Cell Dev Biol 2017; 69:131-139. [PMID: 28478299 DOI: 10.1016/j.semcdb.2017.05.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 04/26/2017] [Accepted: 05/03/2017] [Indexed: 12/20/2022]
Abstract
The cluster of almost 60 protocadherin genes, divided into the α, β and γ subgroups, is a hallmark of vertebrate nervous system evolution. These clustered protocadherins (Pcdhs) are of interest for several reasons, one being the arrangement of the genes, which allows epigenetic regulation at the cluster and single-cell identity. Another reason is the still ambiguous effect of Pcdhs on cell-cell interaction. Unlike the case for classical cadherins, which typically mediate strong cell adhesion and formation of adherens junctions, it has been challenging to ascertain exactly how Pcdhs affect interacting cells. In some instances, Pcdhs appear to promote the association of membranes, while in other cases the Pcdhs are anti-adhesive and cause avoidance of interacting membranes. It is clear that Pcdh extracellular domains bind homophillically in an antiparallel conformation, typical of adhesive interactions. How can molecules that would seemingly bind cells together be able to promote the avoidance of membranes? It is possible that Pcdh trafficking will eventually provide insights into the role of these molecules at the cell surface. We have found that endogenous and expressed Pcdhs are generally less efficient at targeting to cell junctions and synapses than are classical cadherins. Instead, Pcdhs are prominently sequestered in the endolysosome system or other intracellular compartments. What role this trafficking plays in the unique mode of cell-cell interaction is a current topic of investigation. It is tempting to speculate that modulation of endocytosis and endolysosomal trafficking may be a part of the mechanism by which Pcdhs convert from adhesive to avoidance molecules.
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Affiliation(s)
- Greg R Phillips
- Department of Biology, Center for Developmental Neuroscience, College of Staten Island, City University of New York, United States; Program in Neuroscience, The Graduate Center, City University of New York, United States.
| | - Nicole LaMassa
- Department of Biology, Center for Developmental Neuroscience, College of Staten Island, City University of New York, United States
| | - Yan Mei Nie
- Department of Biology, Center for Developmental Neuroscience, College of Staten Island, City University of New York, United States
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Hasegawa S, Kobayashi H, Kumagai M, Nishimaru H, Tarusawa E, Kanda H, Sanbo M, Yoshimura Y, Hirabayashi M, Hirabayashi T, Yagi T. Clustered Protocadherins Are Required for Building Functional Neural Circuits. Front Mol Neurosci 2017; 10:114. [PMID: 28484370 PMCID: PMC5401904 DOI: 10.3389/fnmol.2017.00114] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 04/05/2017] [Indexed: 01/08/2023] Open
Abstract
Neuronal identity is generated by the cell-surface expression of clustered protocadherin (Pcdh) isoforms. In mice, 58 isoforms from three gene clusters, Pcdhα, Pcdhβ, and Pcdhγ, are differentially expressed in neurons. Since cis-heteromeric Pcdh oligomers on the cell surface interact homophilically with that in other neurons in trans, it has been thought that the Pcdh isoform repertoire determines the binding specificity of synapses. We previously described the cooperative functions of isoforms from all three Pcdh gene clusters in neuronal survival and synapse formation in the spinal cord. However, the neuronal loss and the following neonatal lethality prevented an analysis of the postnatal development and characteristics of the clustered-Pcdh-null (Δαβγ) neural circuits. Here, we used two methods, one to generate the chimeric mice that have transplanted Δαβγ neurons into mouse embryos, and the other to generate double mutant mice harboring null alleles of both the Pcdh gene and the proapoptotic gene Bax to prevent neuronal loss. First, our results showed that the surviving chimeric mice that had a high contribution of Δαβγ cells exhibited paralysis and died in the postnatal period. An analysis of neuronal survival in postnatally developing brain regions of chimeric mice clarified that many Δαβγ neurons in the forebrain were spared from apoptosis, unlike those in the reticular formation of the brainstem. Second, in Δαβγ/Bax null double mutants, the central pattern generator (CPG) for locomotion failed to create a left-right alternating pattern even in the absence of neurodegeneraton. Third, calcium imaging of cultured hippocampal neurons showed that the network activity of Δαβγ neurons tended to be more synchronized and lost the variability in the number of simultaneously active neurons observed in the control network. Lastly, a comparative analysis for trans-homophilic interactions of the exogenously introduced single Pcdh-γA3 isoforms between the control and the Δαβγ neurons suggested that the isoform-specific trans-homophilic interactions require a complete match of the expressed isoform repertoire at the contacting sites between interactive neurons. These results suggested that combinations of clustered Pcdh isoforms are required for building appropriate neural circuits.
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Affiliation(s)
- Sonoko Hasegawa
- KOKORO-Biology Group, Laboratories for Integrated Biology, Graduate School of Frontier Biosciences, Osaka UniversitySuita, Japan.,Japan Science and Technology Agency-Core Research for Evolutional Science and Technology, CREST, Osaka UniversitySuita, Osaka, Japan
| | - Hiroaki Kobayashi
- KOKORO-Biology Group, Laboratories for Integrated Biology, Graduate School of Frontier Biosciences, Osaka UniversitySuita, Japan.,Japan Science and Technology Agency-Core Research for Evolutional Science and Technology, CREST, Osaka UniversitySuita, Osaka, Japan
| | - Makiko Kumagai
- KOKORO-Biology Group, Laboratories for Integrated Biology, Graduate School of Frontier Biosciences, Osaka UniversitySuita, Japan.,Japan Science and Technology Agency-Core Research for Evolutional Science and Technology, CREST, Osaka UniversitySuita, Osaka, Japan
| | - Hiroshi Nishimaru
- System Emotional Science, Graduate School of Medicine, University of ToyamaToyama, Japan
| | - Etsuko Tarusawa
- Section of Visual Information Processing, National Institute for Physiological Sciences, National Institutes of Natural SciencesOkazaki, Japan
| | - Hiro Kanda
- KOKORO-Biology Group, Laboratories for Integrated Biology, Graduate School of Frontier Biosciences, Osaka UniversitySuita, Japan.,Japan Science and Technology Agency-Core Research for Evolutional Science and Technology, CREST, Osaka UniversitySuita, Osaka, Japan
| | - Makoto Sanbo
- Section of Mammalian Transgenesis, Center for Genetic Analysis of Behavior, National Institute for Physiological SciencesOkazaki, Japan
| | - Yumiko Yoshimura
- Section of Visual Information Processing, National Institute for Physiological Sciences, National Institutes of Natural SciencesOkazaki, Japan
| | - Masumi Hirabayashi
- Section of Mammalian Transgenesis, Center for Genetic Analysis of Behavior, National Institute for Physiological SciencesOkazaki, Japan
| | - Takahiro Hirabayashi
- KOKORO-Biology Group, Laboratories for Integrated Biology, Graduate School of Frontier Biosciences, Osaka UniversitySuita, Japan.,Japan Science and Technology Agency-Core Research for Evolutional Science and Technology, CREST, Osaka UniversitySuita, Osaka, Japan
| | - Takeshi Yagi
- KOKORO-Biology Group, Laboratories for Integrated Biology, Graduate School of Frontier Biosciences, Osaka UniversitySuita, Japan.,Japan Science and Technology Agency-Core Research for Evolutional Science and Technology, CREST, Osaka UniversitySuita, Osaka, Japan
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