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Huene AL, Nicotra ML. Cell Aggregation Assays for Homophilic Interactions Between Cell Surface Proteins. Methods Mol Biol 2022; 2421:91-102. [PMID: 34870813 DOI: 10.1007/978-1-0716-1944-5_6] [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] [Indexed: 06/13/2023]
Abstract
Many proteins expressed on the cellular surface provide signaling and cell adhesion properties required for vital cellular functions. These binding interactions can occur between different but complementary proteins such as a ligand and receptor, or between the same protein acting as both ligand and receptor. The cell aggregation assay is a straightforward technique to identify homophilic interactions from such proteins. Here we describe the procedure for testing proteins via cell aggregation assays in HEK293T cells.
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Affiliation(s)
- Aidan L Huene
- Department of Surgery and Center for Evolutionary Biology and Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Matthew L Nicotra
- Departments of Surgery and Immunology, Thomas E. Starzl Transplantation Institute, and Center for Evolutionary Biology and Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
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2
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McLeod CM, Garrett AM. Mouse models for the study of clustered protocadherins. Curr Top Dev Biol 2022; 148:115-137. [PMID: 35461562 PMCID: PMC9152800 DOI: 10.1016/bs.ctdb.2021.12.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Since their first description, the clustered protocadherins (cPcdhs) have sparked interest for their potential to generate diverse cell-surface recognition cues and their widespread expression in the nervous system. Through the use of mouse models, we have learned a great deal about the functions served by cPcdhs, and how their molecular diversity is regulated. cPcdhs are essential contributors to a host of processes during neural circuit formation, including neuronal survival, dendritic and axonal branching, self-avoidance and targeting, and synapse formation. Their expression is controlled by the interplay of epigenetic marks with proximal and distal elements involving high order DNA looping, regulating transcription factor binding. Here, we will review various mouse models targeting the cPcdh locus and how they have been instructive in uncovering the regulation and function of the cPcdhs.
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Affiliation(s)
- Cathy M. McLeod
- Department of Pharmacology, Wayne State University School of Medicine
| | - Andrew M. Garrett
- Department of Pharmacology, Wayne State University School of Medicine,Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine
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3
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Abstract
Astrocytes are the most abundant glial cells in the mammalian brain and directly participate in the proper functioning of the nervous system by regulating ion homeostasis, controlling glutamate reuptake, and maintaining the blood-brain barrier. In the last two decades, a growing body of work also identified critical roles for astrocytes in regulating synaptic connectivity. Stemming from the observation that functional and morphological development of astrocytes occur concurrently with synapse formation and maturation, these studies revealed that both developmental processes are directly linked. In fact, astrocytes both physically contact numerous synaptic structures and actively instruct many aspects of synaptic development and function via a plethora of secreted and adhesion-based molecular signals. The complex astrocyte-to-neuron signaling modalities control different stages of synaptic development such as regulating the initial formation of structural synapses as well as their functional maturation. Furthermore, the synapse-modulating functions of astrocytes are evolutionarily conserved and contribute to the development and plasticity of diverse classes of synapses and circuits throughout the central nervous system. Importantly, because impaired synapse formation and function is a hallmark of many neurodevelopmental disorders, deficits in astrocytes are likely to be major contributors to disease pathogenesis. In this chapter, we review our current understanding of the cellular and molecular mechanisms by which astrocytes contribute to synapse development and discuss the bidirectional secretion-based and contact-mediated mechanisms responsible for these essential developmental processes.
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Affiliation(s)
- Christabel X Tan
- Department of Cell Biology, Duke University Medical Center, Durham, NC, United States
| | - Caley J Burrus Lane
- Department of Cell Biology, Duke University Medical Center, Durham, NC, United States; Department of Neurobiology, Duke University Medical Center, Durham, NC, United States
| | - Cagla Eroglu
- Department of Cell Biology, Duke University Medical Center, Durham, NC, United States; Department of Neurobiology, Duke University Medical Center, Durham, NC, United States; Duke Institute for Brain Sciences, Durham, NC, United States; Regeneration Next Initiative, Duke University, Durham, NC, United States.
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4
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Gan L, Yang C, Shu Y, Liu F, Sun R, Deng B, Xu J, Huang G, Qu C, Gong B, Li J. Identification of a novel homozygous nonsense mutation in the CDHR1 gene in a Chinese family with autosomal recessive retinitis pigmentosa. Clin Chim Acta 2020; 507:17-22. [PMID: 32277948 DOI: 10.1016/j.cca.2020.04.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 03/07/2020] [Accepted: 04/07/2020] [Indexed: 11/20/2022]
Abstract
BACKGROUND Retinitis pigmentosa (RP) is a group of hereditary retinal diseases that often lead to blindness. Although 80 genes associated with RP have been observed, the genetic mechanism of approximately 40% RP cases remains unknown. This study was to investigate the disease-causing gene in a Han Chinese family with autosomal recessive RP (arRP). METHODS A Chinese arRP family (RP-2373), consisting of three affected siblings and eight unaffected family members, was recruited in this study. All participants underwent complete ophthalmic examinations, including visual field testing, best-corrected visual acuity, fundus photography and electroretinography. Whole exome sequencing was performed on the three patients and Sanger sequencing was utilized to confirm the mutations identified in all family members and 2010 unrelated controls. RESULTS A novel homozygous nonsense mutation, c.1231C > T (p.Q411X) in the Cadherin-Related Family Member 1 (CDHR1) gene was identified in the RP-2373 family. The proband and her two affected sisters were found to carry a homozygous mutation that led to a substitution of Glutamine to a stop codon. Other unaffected members and 2010 ethnic-matched controls lacked this mutation. These data showed a complete co-segregation of the CDHR1 mutation with arRP in this family. The p.Q411X mutation was observed to affect highly conserved amino acid residue of CHDR1. CONCLUSION Our study expanded the CDHR1 mutation spectrum of RP in the Chinese population, which might help to better understand RP molecular pathogenesis.
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Affiliation(s)
- Li Gan
- Department of Laboratory Medicine and Key Laboratory for Human Disease Gene Study of Sichuan Province, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, China
| | - Chen Yang
- Department of Laboratory Medicine and Key Laboratory for Human Disease Gene Study of Sichuan Province, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, China
| | - Yi Shu
- School of Medical Technology, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Fang Liu
- College of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Ruiting Sun
- Department of Laboratory Medicine and Key Laboratory for Human Disease Gene Study of Sichuan Province, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, China
| | - Bolin Deng
- Department of Ophthalmology, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, China
| | - Jiaxin Xu
- Department of Laboratory Medicine and Key Laboratory for Human Disease Gene Study of Sichuan Province, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, China
| | - Guo Huang
- Department of Laboratory Medicine and Key Laboratory for Human Disease Gene Study of Sichuan Province, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, China
| | - Chao Qu
- Department of Ophthalmology, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, China
| | - Bo Gong
- Department of Laboratory Medicine and Key Laboratory for Human Disease Gene Study of Sichuan Province, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, China; Institute of Chengdu Biology, Sichuan Translational Medicine Hospital, Chinese Academy of Sciences, Chengdu 610072, China.
| | - Jing Li
- Department of Ophthalmology, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, China.
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5
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Pancho A, Aerts T, Mitsogiannis MD, Seuntjens E. Protocadherins at the Crossroad of Signaling Pathways. Front Mol Neurosci 2020; 13:117. [PMID: 32694982 PMCID: PMC7339444 DOI: 10.3389/fnmol.2020.00117] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 06/08/2020] [Indexed: 12/25/2022] Open
Abstract
Protocadherins (Pcdhs) are cell adhesion molecules that belong to the cadherin superfamily, and are subdivided into clustered (cPcdhs) and non-clustered Pcdhs (ncPcdhs) in vertebrates. In this review, we summarize their discovery, expression mechanisms, and roles in neuronal development and cancer, thereby highlighting the context-dependent nature of their actions. We furthermore provide an extensive overview of current structural knowledge, and its implications concerning extracellular interactions between cPcdhs, ncPcdhs, and classical cadherins. Next, we survey the known molecular action mechanisms of Pcdhs, emphasizing the regulatory functions of proteolytic processing and domain shedding. In addition, we outline the importance of Pcdh intracellular domains in the regulation of downstream signaling cascades, and we describe putative Pcdh interactions with intracellular molecules including components of the WAVE complex, the Wnt pathway, and apoptotic cascades. Our overview combines molecular interaction data from different contexts, such as neural development and cancer. This comprehensive approach reveals potential common Pcdh signaling hubs, and points out future directions for research. Functional studies of such key factors within the context of neural development might yield innovative insights into the molecular etiology of Pcdh-related neurodevelopmental disorders.
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Affiliation(s)
- Anna Pancho
- Laboratory of Developmental Neurobiology, Department of Biology, KU Leuven, Leuven, Belgium
| | - Tania Aerts
- Laboratory of Developmental Neurobiology, Department of Biology, KU Leuven, Leuven, Belgium
| | - Manuela D Mitsogiannis
- Laboratory of Developmental Neurobiology, Department of Biology, KU Leuven, Leuven, Belgium
| | - Eve Seuntjens
- Laboratory of Developmental Neurobiology, Department of Biology, KU Leuven, Leuven, Belgium
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Light SEW, Jontes JD. δ-Protocadherins: Organizers of neural circuit assembly. Semin Cell Dev Biol 2017; 69:83-90. [PMID: 28751249 DOI: 10.1016/j.semcdb.2017.07.037] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 07/21/2017] [Accepted: 07/21/2017] [Indexed: 02/08/2023]
Abstract
The δ-protocadherins comprise a small family of homophilic cell adhesion molecules within the larger cadherin superfamily. They are essential for neural development as mutations in these molecules give rise to human neurodevelopmental disorders, such as schizophrenia and epilepsy, and result in behavioral defects in animal models. Despite their importance to neural development, a detailed understanding of their mechanisms and the ways in which their loss leads to changes in neural function is lacking. However, recent results have begun to reveal roles for the δ-protocadherins in both regulation of neurogenesis and lineage-dependent circuit assembly, as well as in contact-dependent motility and selective axon fasciculation. These evolutionarily conserved mechanisms could have a profound impact on the robust assembly of the vertebrate nervous system. Future work should be focused on unraveling the molecular mechanisms of the δ-protocadherins and understanding how this family functions broadly to regulate neural development.
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Affiliation(s)
- Sarah E W Light
- Department of Neuroscience, Neuroscience Graduate Program, Ohio State University, 1060 Carmack Rd., 113 Rightmire Hall, Columbus, OH 43210, United States
| | - James D Jontes
- Department of Neuroscience, Neuroscience Graduate Program, Ohio State University, 1060 Carmack Rd., 113 Rightmire Hall, Columbus, OH 43210, United States.
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7
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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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Cooper SR, Jontes JD, Sotomayor M. Structural determinants of adhesion by Protocadherin-19 and implications for its role in epilepsy. eLife 2016; 5. [PMID: 27787195 PMCID: PMC5115871 DOI: 10.7554/elife.18529] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 10/25/2016] [Indexed: 01/27/2023] Open
Abstract
Non-clustered δ-protocadherins are homophilic cell adhesion molecules essential for the development of the vertebrate nervous system, as several are closely linked to neurodevelopmental disorders. Mutations in protocadherin-19 (PCDH19) result in a female-limited, infant-onset form of epilepsy (PCDH19-FE). Over 100 mutations in PCDH19 have been identified in patients with PCDH19-FE, about half of which are missense mutations in the adhesive extracellular domain. Neither the mechanism of homophilic adhesion by PCDH19, nor the biochemical effects of missense mutations are understood. Here we present a crystallographic structure of the minimal adhesive fragment of the zebrafish Pcdh19 extracellular domain. This structure reveals the adhesive interface for Pcdh19, which is broadly relevant to both non-clustered δ and clustered protocadherin subfamilies. In addition, we show that several PCDH19-FE missense mutations localize to the adhesive interface and abolish Pcdh19 adhesion in in vitro assays, thus revealing the biochemical basis of their pathogenic effects during brain development. DOI:http://dx.doi.org/10.7554/eLife.18529.001 As the brain develops, its basic building blocks – cells called neurons – need to form the correct connections with one another in order to give rise to neural circuits. A mistake that leads to the formation of incorrect connections can result in a number of disorders or brain abnormalities. Proteins called cadherins that are present on the surface of neurons enable them to stick to their correct partners like Velcro. One of these proteins is called Protocadherin-19. However, it was not fully understood how this protein forms an adhesive bond with other Protocadherin-19 molecules, or how some of the proteins within the cadherin family are able to distinguish between one another. Cooper et al. used X-ray crystallography to visualize the molecular structure of Protocadherin-19 taken from zebrafish in order to better understand the adhesive bond that these proteins form with each other. In addition, the new structure showed the sites of the mutations that cause a form of epilepsy in infant females. From this, Cooper et al. could predict how the mutations would disrupt Protocadherin-19’s shape and function. The structures revealed that Protocadherin-19 molecules from adjacent cells engage in a “forearm handshake” to form the bond that connects neurons. Some of the mutations that cause epilepsy occur in the region responsible for this Protocadherin-19 forearm handshake. Laboratory experiments confirmed that these mutations impair the formation of the adhesive bond, revealing the molecular basis for some of the mutations that underlie Protocadherin-19-female-limited epilepsy. Other cadherin molecules may interact via a similar forearm handshake; this could be investigated in future experiments. It also remains to be discovered how brain wiring depends on Protocadherin-19 adhesion in animal development, and how altering these proteins can rewire developing brain circuits. DOI:http://dx.doi.org/10.7554/eLife.18529.002
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Affiliation(s)
- Sharon R Cooper
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, United States.,Department of Neuroscience, The Ohio State University, Columbus, United States
| | - James D Jontes
- Department of Neuroscience, The Ohio State University, Columbus, United States
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, United States
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9
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Shan M, Su Y, Kang W, Gao R, Li X, Zhang G. Aberrant expression and functions of protocadherins in human malignant tumors. Tumour Biol 2016; 37:12969-12981. [PMID: 27449047 DOI: 10.1007/s13277-016-5169-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 07/12/2016] [Indexed: 12/11/2022] Open
Abstract
Protocadherins (PCDHs) are a group of transmembrane proteins belonging to the cadherin superfamily and are subdivided into "clustered" and "non-clustered" groups. PCDHs vary in both structure and interaction partners and thus regulate multiple biological responses in complex and versatile patterns. Previous researches showed that PCDHs regulated the development of brain and were involved in some neuronal diseases. Recently, studies have revealed aberrant expression of PCDHs in various human malignant tumors. The down-regulation or absence of PCDHs in malignant cells has been associated with cancer progression. Further researches suggest that PCDHs may play major functions as tumor suppressor by inhibiting the proliferation and metastasis of cancer cells. In this review, we focus on the altered expression of PCDHs and their roles in the development of cancer progression. We also discuss the potential mechanisms, by which PCDHs are aberrantly expressed, and its implications in regulating cancers.
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Affiliation(s)
- Ming Shan
- Department of Breast Surgery, the Affiliated Tumor Hospital of Harbin Medical University, Harbin, China
| | - Yonghui Su
- Department of Breast Surgery, the Affiliated Tumor Hospital of Harbin Medical University, Harbin, China
| | - Wenli Kang
- Department of Oncology, General Hospital of Hei Longjiang Province Land Reclamation Headquarter, Harbin, China
| | - Ruixin Gao
- Department of Breast Surgery, The First Hospital of Qiqihaer City, Qiqihaer, China
| | - Xiaobo Li
- Department of Pathology, Harbin Medical University, Harbin, China.
| | - Guoqiang Zhang
- Department of Breast Surgery, the Affiliated Tumor Hospital of Harbin Medical University, Harbin, China.
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Nicoludis JM, Lau SY, Schärfe CPI, Marks DS, Weihofen WA, Gaudet R. Structure and Sequence Analyses of Clustered Protocadherins Reveal Antiparallel Interactions that Mediate Homophilic Specificity. Structure 2015; 23:2087-98. [PMID: 26481813 PMCID: PMC4635037 DOI: 10.1016/j.str.2015.09.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 09/14/2015] [Accepted: 09/15/2015] [Indexed: 01/07/2023]
Abstract
Clustered protocadherin (Pcdh) proteins mediate dendritic self-avoidance in neurons via specific homophilic interactions in their extracellular cadherin (EC) domains. We determined crystal structures of EC1-EC3, containing the homophilic specificity-determining region, of two mouse clustered Pcdh isoforms (PcdhγA1 and PcdhγC3) to investigate the nature of the homophilic interaction. Within the crystal lattices, we observe antiparallel interfaces consistent with a role in trans cell-cell contact. Antiparallel dimerization is supported by evolutionary correlations. Two interfaces, located primarily on EC2-EC3, involve distinctive clustered Pcdh structure and sequence motifs, lack predicted glycosylation sites, and contain residues highly conserved in orthologs but not paralogs, pointing toward their biological significance as homophilic interaction interfaces. These two interfaces are similar yet distinct, reflecting a possible difference in interaction architecture between clustered Pcdh subfamilies. These structures initiate a molecular understanding of clustered Pcdh assemblies that are required to produce functional neuronal networks.
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Affiliation(s)
- John M. Nicoludis
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA, 02138, USA
| | - Sze-Yi Lau
- Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA, 02138, USA
| | - Charlotta P. I. Schärfe
- Department of Systems Biology, Harvard Medical School, Boston, MA, 02115, USA,Applied Bioinformatics, Department of Computer Science, University of Tübingen, Tübingen, Germany
| | - Debora S. Marks
- Department of Systems Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Wilhelm A. Weihofen
- Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA, 02138, USA,Correspondence: (R. G.), (W. A.W.)
| | - Rachelle Gaudet
- Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA, 02138, USA,Correspondence: (R. G.), (W. A.W.)
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Rubinstein R, Thu CA, Goodman KM, Wolcott HN, Bahna F, Mannepalli S, Ahlsen G, Chevee M, Halim A, Clausen H, Maniatis T, Shapiro L, Honig B. Molecular logic of neuronal self-recognition through protocadherin domain interactions. Cell 2015; 163:629-42. [PMID: 26478182 DOI: 10.1016/j.cell.2015.09.026] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 07/17/2015] [Accepted: 08/27/2015] [Indexed: 12/27/2022]
Abstract
Self-avoidance, a process preventing interactions of axons and dendrites from the same neuron during development, is mediated in vertebrates through the stochastic single-neuron expression of clustered protocadherin protein isoforms. Extracellular cadherin (EC) domains mediate isoform-specific homophilic binding between cells, conferring cell recognition through a poorly understood mechanism. Here, we report crystal structures for the EC1-EC3 domain regions from four protocadherin isoforms representing the α, β, and γ subfamilies. All are rod shaped and monomeric in solution. Biophysical measurements, cell aggregation assays, and computational docking reveal that trans binding between cells depends on the EC1-EC4 domains, which interact in an antiparallel orientation. We also show that the EC6 domains are required for the formation of cis-dimers. Overall, our results are consistent with a model in which protocadherin cis-dimers engage in a head-to-tail interaction between EC1-EC4 domains from apposed cell surfaces, possibly forming a zipper-like protein assembly, and thus providing a size-dependent self-recognition mechanism.
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Affiliation(s)
- Rotem Rubinstein
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Department of Systems Biology, Columbia University, New York, NY 10032, USA
| | - Chan Aye Thu
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Kerry Marie Goodman
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Holly Noelle Wolcott
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Fabiana Bahna
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA
| | - Seetha Mannepalli
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Goran Ahlsen
- Department of Systems Biology, Columbia University, New York, NY 10032, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA
| | - Maxime Chevee
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Adnan Halim
- Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Henrik Clausen
- Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Tom Maniatis
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Lawrence Shapiro
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Department of Systems Biology, Columbia University, New York, NY 10032, USA.
| | - Barry Honig
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Department of Systems Biology, Columbia University, New York, NY 10032, USA; Department of Medicine, Columbia University, New York, NY 10032, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10032, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA.
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12
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Massah S, Beischlag TV, Prefontaine GG. Epigenetic events regulating monoallelic gene expression. Crit Rev Biochem Mol Biol 2015; 50:337-58. [PMID: 26155735 DOI: 10.3109/10409238.2015.1064350] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In mammals, generally it is assumed that the genes inherited from each parent are expressed to similar levels. However, it is now apparent that in non-sex chromosomes, 6-10% of genes are selected for monoallelic expression. Monoallelic expression or allelic exclusion is established either in an imprinted (parent-of-origin) or a stochastic manner. The stochastic model explains random selection while the imprinted model describes parent-of-origin specific selection of alleles for expression. Allelic exclusion occurs during X chromosome inactivation, parent-of-origin expression of imprinted genes and stochastic monoallelic expression of cell surface molecules, clustered protocadherin (PCDH) genes. Mis-regulation or loss of allelic exclusion contributes to developmental diseases. Epigenetic mechanisms are fundamental players that determine this type of expression despite a homogenous genetic background. DNA methylation and histone modifications are two mediators of the epigenetic phenomena. The majority of DNA methylation is found on cytosines of the CpG dinucleotide in mammals. Several covalent modifications of histones change the electrostatic forces between DNA and histones modifying gene expression. Long-range chromatin interactions organize chromatin into transcriptionally permissive and prohibitive regions leading to simultaneous regulation of gene expression and repression. Non-coding RNAs (ncRNAs) are also players in regulating gene expression. Together, these epigenetic mechanisms fine-tune gene expression levels essential for normal development and survival. In this review, first we discuss what is known about monoallelic gene expression. Then, we focus on the molecular mechanisms that regulate expression of three monoallelically expressed gene classes: the X-linked genes, selected imprinted genes and PCDH genes.
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Affiliation(s)
- Shabnam Massah
- a The Faculty of Health Sciences , Simon Fraser University , Burnaby , BC , Canada
| | - Timothy V Beischlag
- a The Faculty of Health Sciences , Simon Fraser University , Burnaby , BC , Canada
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13
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Coughlin GM, Kurrasch DM. Protocadherins and hypothalamic development: do they play an unappreciated role? J Neuroendocrinol 2015; 27:544-55. [PMID: 25845440 DOI: 10.1111/jne.12280] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Revised: 03/26/2015] [Accepted: 03/27/2015] [Indexed: 12/17/2022]
Abstract
Normal brain development requires coordinated cell movements at precise times. It has long been established that cell-cell adhesion proteins of the cadherin superfamily are involved in the adhesion and sorting of cells during tissue morphogenesis. In the present review, we focus on protocadherins, which form the largest subfamily of the cadherin superfamily and mediate homophilic cell-cell adhesion in the developing brain. These molecules are highly expressed during neural development and the exact roles that they play are still emerging. Although, historically, protocadherins were considered to provide mechanical and chemical connections between adjacent cells, recent research suggests that they may also serve as molecular identity markers of neurones to help guide cell recognition and sorting, cell migration, outgrowth of neuronal processes, and synapse formation. This phenomenon of single cell diversity stems, in part, from the vast variation in protein structure, genomic organisation and molecular function of the protocadherins. Although expression profiles and genetic manipulations have provided evidence for the role of protocadherins in the developing brain, we have only begun to construct a complete understanding of protocadherin function. We examine our current understanding of how protocadherins influence brain development and discuss the possible roles for this large superfamily within the hypothalamus. We conclude that further research into these underappreciated but vitally important genes will shed insight into hypothalamic development and perhaps the underlying aetiology of neuroendocrine disorders.
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Affiliation(s)
- G M Coughlin
- Department of Medical Genetics, University of Calgary, Calgary, AB, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
| | - D M Kurrasch
- Department of Medical Genetics, University of Calgary, Calgary, AB, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
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Friedman LG, Benson DL, Huntley GW. Cadherin-based transsynaptic networks in establishing and modifying neural connectivity. Curr Top Dev Biol 2015; 112:415-65. [PMID: 25733148 DOI: 10.1016/bs.ctdb.2014.11.025] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
It is tacitly understood that cell adhesion molecules (CAMs) are critically important for the development of cells, circuits, and synapses in the brain. What is less clear is what CAMs continue to contribute to brain structure and function after the early period of development. Here, we focus on the cadherin family of CAMs to first briefly recap their multidimensional roles in neural development and then to highlight emerging data showing that with maturity, cadherins become largely dispensible for maintaining neuronal and synaptic structure, instead displaying new and narrower roles at mature synapses where they critically regulate dynamic aspects of synaptic signaling, structural plasticity, and cognitive function. At mature synapses, cadherins are an integral component of multiprotein networks, modifying synaptic signaling, morphology, and plasticity through collaborative interactions with other CAM family members as well as a variety of neurotransmitter receptors, scaffolding proteins, and other effector molecules. Such recognition of the ever-evolving functions of synaptic cadherins may yield insight into the pathophysiology of brain disorders in which cadherins have been implicated and that manifest at different times of life.
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Affiliation(s)
- Lauren G Friedman
- Fishberg Department of Neuroscience, Friedman Brain Institute and the Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Deanna L Benson
- Fishberg Department of Neuroscience, Friedman Brain Institute and the Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, USA
| | - George W Huntley
- Fishberg Department of Neuroscience, Friedman Brain Institute and the Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, USA.
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15
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Ortiz-Medina H, Emond MR, Jontes JD. Zebrafish calsyntenins mediate homophilic adhesion through their amino-terminal cadherin repeats. Neuroscience 2014; 286:87-96. [PMID: 25463516 DOI: 10.1016/j.neuroscience.2014.11.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 11/07/2014] [Accepted: 11/18/2014] [Indexed: 11/20/2022]
Abstract
The calsyntenins are atypical members of the cadherin superfamily that have been implicated in learning in Caenorhabditis elegans and memory formation in humans. As members of the cadherin superfamily, they could mediate cell-cell adhesion, although their adhesive properties have not been investigated. As an initial step in characterizing the calsyntenins, we have cloned clstn1, clstn2 and clstn3 from the zebrafish and determined their expression in the developing zebrafish nervous system. The three genes each have broad, yet distinct, expression patterns in the zebrafish brain. Each of the ectodomains mediates homophilic interactions through two, amino-terminal cadherin repeats. In bead sorting assays, the calsyntenin ectodomains do not exhibit homophilic preferences. These data support the idea that calsyntenins could either act as adhesion molecules or as diffusible, homophilic or heterophilic ligands in the vertebrate nervous system.
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Affiliation(s)
- H Ortiz-Medina
- Department of Neuroscience, Ohio State University Medical Center, United States
| | - M R Emond
- Department of Neuroscience, Ohio State University Medical Center, United States
| | - J D Jontes
- Department of Neuroscience, Ohio State University Medical Center, United States.
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16
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Wang KH, Lin CJ, Liu CJ, Liu DW, Huang RL, Ding DC, Weng CF, Chu TY. Global methylation silencing of clustered proto-cadherin genes in cervical cancer: serving as diagnostic markers comparable to HPV. Cancer Med 2014; 4:43-55. [PMID: 25418975 PMCID: PMC4312117 DOI: 10.1002/cam4.335] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 07/23/2014] [Accepted: 08/01/2014] [Indexed: 12/19/2022] Open
Abstract
Epigenetic remodeling of cell adhesion genes is a common phenomenon in cancer invasion. This study aims to investigate global methylation of cell adhesion genes in cervical carcinogenesis and to apply them in early detection of cancer from cervical scraping. Genome-wide methylation array was performed on an investigation cohort, including 16 cervical intraepithelial neoplasia 3 (CIN3) and 20 cervical cancers (CA) versus 12 each of normal, inflammation and CIN1 as controls. Twelve members of clustered proto-cadherin (PCDH) genes were collectively methylated and silenced, which were validated in cancer cells of the cervix, endometrium, liver, head and neck, breast, and lung. In an independent cohort including 107 controls, 66 CIN1, 85 CIN2/3, and 38 CA, methylated PCDHA4 and PCDHA13 were detected in 2.8%, 24.2%, 52.9%, and 84.2% (P < 10−25), and 2.8%, 24.2%, 50.6%, and 94.7% (P < 10−29), respectively. In diagnosis of CIN2 or more severe lesion of the cervix, a combination test of methylated PCDHA4 or PCDHA13 from cervical scraping had a sensitivity, specificity, positive predictive value, and negative predictive value of 74.8%, 80.3%, 73%, and 81.8%, respectively. Testing of this combination from cervical scraping is equally sensitive but more specific than human papillomavirus (HPV) test in diagnosis of CIN2 or more severe lesions. The study disclosed a collective methylation of PCDH genes in cancer of cervix and other sites. At least two of them can be promising diagnostic markers for cervical cancer noninferior to HPV.
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Affiliation(s)
- Kai-Hung Wang
- Department of Research, Center for Cervical Cancer Prevention, Buddhist Tzu Chi General HospitalHualien, Taiwan
- Institute of Medical Sciences, School of Medicine, Tzu Chi UniversityHualien, Taiwan
| | - Cuei-Jyuan Lin
- Department of Research, Center for Cervical Cancer Prevention, Buddhist Tzu Chi General HospitalHualien, Taiwan
- Institute of Medical Sciences, School of Medicine, Tzu Chi UniversityHualien, Taiwan
| | - Chou-Jen Liu
- Department of Life Science and Institute of Biotechnology, National Dong Hwa UniversityHualien, Taiwan
| | - Dai-Wei Liu
- Department of Radiation Oncology, Buddhist Tzu Chi General HospitalHualien, Taiwan
| | - Rui-Lan Huang
- Department of Obstetrics and Gynecology, Shuang Ho Hospital, Taipei Medical UniversityTaipei, Taiwan
| | - Dah-Ching Ding
- Institute of Medical Sciences, School of Medicine, Tzu Chi UniversityHualien, Taiwan
- Department of Obstetrics and Gynecology, Buddhist Tzu Chi General HospitalHualien, Taiwan
| | - Ching-Feng Weng
- Department of Life Science and Institute of Biotechnology, National Dong Hwa UniversityHualien, Taiwan
| | - Tang-Yuan Chu
- Department of Research, Center for Cervical Cancer Prevention, Buddhist Tzu Chi General HospitalHualien, Taiwan
- Institute of Medical Sciences, School of Medicine, Tzu Chi UniversityHualien, Taiwan
- Department of Obstetrics and Gynecology, Buddhist Tzu Chi General HospitalHualien, Taiwan
- Correspondence Tang-Yuan Chu, Department of Obstetrics and Gynecology, Buddhist Tzu Chi General Hospital, 707, Sec. 3, Jhung-Yang Road, Hualien 970, Taiwan., Tel: +886-38561825 (ext. 5610);, Fax: +886-38577161;, E-mail:
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Conservation weighting functions enable covariance analyses to detect functionally important amino acids. PLoS One 2014; 9:e107723. [PMID: 25379728 PMCID: PMC4224327 DOI: 10.1371/journal.pone.0107723] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 07/31/2014] [Indexed: 01/22/2023] Open
Abstract
The explosive growth in the number of protein sequences gives rise to the possibility of using the natural variation in sequences of homologous proteins to find residues that control different protein phenotypes. Because in many cases different phenotypes are each controlled by a group of residues, the mutations that separate one version of a phenotype from another will be correlated. Here we incorporate biological knowledge about protein phenotypes and their variability in the sequence alignment of interest into algorithms that detect correlated mutations, improving their ability to detect the residues that control those phenotypes. We demonstrate the power of this approach using simulations and recent experimental data. Applying these principles to the protein families encoded by Dscam and Protocadherin allows us to make testable predictions about the residues that dictate the specificity of molecular interactions.
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18
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Humphreys GI, Ziegler YS, Nardulli AM. 17β-estradiol modulates gene expression in the female mouse cerebral cortex. PLoS One 2014; 9:e111975. [PMID: 25372139 PMCID: PMC4221195 DOI: 10.1371/journal.pone.0111975] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 10/10/2014] [Indexed: 01/13/2023] Open
Abstract
17β-estradiol (E2) plays critical roles in a number of target tissues including the mammary gland, reproductive tract, bone, and brain. Although it is clear that E2 reduces inflammation and ischemia-induced damage in the cerebral cortex, the molecular mechanisms mediating the effects of E2 in this brain region are lacking. Thus, we examined the cortical transcriptome using a mouse model system. Female adult mice were ovariectomized and implanted with silastic tubing containing oil or E2. After 7 days, the cerebral cortices were dissected and RNA was isolated and analyzed using RNA-sequencing. Analysis of the transcriptomes of control and E2-treated animals revealed that E2 treatment significantly altered the transcript levels of 88 genes. These genes were associated with long term synaptic potentiation, myelination, phosphoprotein phosphatase activity, mitogen activated protein kinase, and phosphatidylinositol 3-kinase signaling. E2 also altered the expression of genes linked to lipid synthesis and metabolism, vasoconstriction and vasodilation, cell-cell communication, and histone modification. These results demonstrate the far-reaching and diverse effects of E2 in the cerebral cortex and provide valuable insight to begin to understand cortical processes that may fluctuate in a dynamic hormonal environment.
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Affiliation(s)
- Gwendolyn I. Humphreys
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Yvonne S. Ziegler
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Ann M. Nardulli
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
- * E-mail:
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19
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Emond MR, Jontes JD. Bead aggregation assays for the characterization of putative cell adhesion molecules. J Vis Exp 2014:e51762. [PMID: 25350770 DOI: 10.3791/51762] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Cell-cell adhesion is fundamental to multicellular life and is mediated by a diverse array of cell surface proteins. However, the adhesive interactions for many of these proteins are poorly understood. Here we present a simple, rapid method for characterizing the adhesive properties of putative homophilic cell adhesion molecules. Cultured HEK293 cells are transfected with DNA plasmid encoding a secreted, epitope-tagged ectodomain of a cell surface protein. Using functionalized beads specific for the epitope tag, the soluble, secreted fusion protein is captured from the culture medium. The coated beads can then be used directly in bead aggregation assays or in fluorescent bead sorting assays to test for homophilic adhesion. If desired, mutagenesis can then be used to elucidate the specific amino acids or domains required for adhesion. This assay requires only small amounts of expressed protein, does not require the production of stable cell lines, and can be accomplished in 4 days.
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20
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Leonardi E, Sartori S, Vecchi M, Bettella E, Polli R, Palma LD, Boniver C, Murgia A. Identification of four novel PCDH19 Mutations and prediction of their functional impact. Ann Hum Genet 2014; 78:389-98. [PMID: 25227595 DOI: 10.1111/ahg.12082] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 07/10/2014] [Indexed: 11/29/2022]
Abstract
The PCDH19 gene encodes protocadherin-19, a transmembrane protein with six cadherin (EC) domains, containing adhesive interfaces likely to be involved in neuronal connection. Over a hundred mostly private mutations have been identified in girls with epilepsy, with or without intellectual disability (ID). Furthermore, transmitting hemizygous males are devoid of seizures or ID, making it difficult to establish the pathogenic nature of newly identified variants. Here, we describe an integrated approach to evaluate the pathogenicity of four novel PCDH19 mutations. Segregation analysis has been complemented with an in silico analysis of mutation effects at the protein level. Using sequence information, we compared different computational prediction methods. We used homology modeling to build structural models of two PCDH19 EC-domains, and compared wild-type and mutant models to identify differences in residue interactions or biochemical properties of the model surfaces. Our analysis suggests different molecular effects of the novel mutations in exerting their pathogenic role. Two of them interfere with or alter functional residues predicted to mediate ligand or protein binding, one alters the EC-domain folding stability; the frame-shift mutation produces a truncated protein lacking the intracellular domain. Interestingly, the girl carrying the putative loss of function mutation presents the most severe phenotype.
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Affiliation(s)
- Emanuela Leonardi
- Molecular Genetics of Neurodevelopment, Department of Women's and Children's Health, University of Padua, Padua, Italy
| | - Stefano Sartori
- Pediatric Neurology Unit, Department of Women's and Children's Health, University of Padua, Padua, Italy
| | - Marilena Vecchi
- Pediatric Neurophysiology Unit, Department of Women's and Children's Health, University of Padua, Padua, Italy
| | - Elisa Bettella
- Molecular Genetics of Neurodevelopment, Department of Women's and Children's Health, University of Padua, Padua, Italy
| | - Roberta Polli
- Molecular Genetics of Neurodevelopment, Department of Women's and Children's Health, University of Padua, Padua, Italy
| | - Luca De Palma
- Pediatric Neurophysiology Unit, Department of Women's and Children's Health, University of Padua, Padua, Italy
| | - Clementina Boniver
- Pediatric Neurophysiology Unit, Department of Women's and Children's Health, University of Padua, Padua, Italy
| | - Alessandra Murgia
- Molecular Genetics of Neurodevelopment, Department of Women's and Children's Health, University of Padua, Padua, Italy
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21
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Sotomayor M, Gaudet R, Corey DP. Sorting out a promiscuous superfamily: towards cadherin connectomics. Trends Cell Biol 2014; 24:524-36. [PMID: 24794279 DOI: 10.1016/j.tcb.2014.03.007] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 03/23/2014] [Accepted: 03/25/2014] [Indexed: 12/21/2022]
Abstract
Members of the cadherin superfamily of proteins are involved in diverse biological processes such as morphogenesis, sound transduction, and neuronal connectivity. Key to cadherin function is their extracellular domain containing cadherin repeats, which can mediate interactions involved in adhesion and cell signaling. Recent cellular, biochemical, and structural studies have revealed that physical interaction among cadherins is more complex than originally thought. Here we review work on new cadherin complexes and discuss how the classification of the mammalian family can be used to search for additional cadherin-interacting partners. We also highlight some of the challenges in cadherin research; namely, the characterization of a cadherin connectome in biochemical and structural terms, as well as the elucidation of molecular mechanisms underlying the functional diversity of nonclassical cadherins in vivo.
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Affiliation(s)
- Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus OH 43210, USA.
| | - Rachelle Gaudet
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
| | - David P Corey
- Howard Hughes Medical Institute, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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22
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Abstract
The mammalian brain is a complex multicellular system involving enormous numbers of neurons. The neuron is the basic functional unit of the brain, and neurons are organized by specialized intercellular connections into circuits with many other neurons. Physiological studies have revealed that individual neurons have remarkably selective response properties, and this individuality is a fundamental requirement for building complex and functionally diverse neural networks. Recent molecular biological studies have revealed genetic bases for neuronal individuality in the mammalian brain. For example, in the rodent olfactory epithelium, individual olfactory neurons express only one type of odorant receptor (OR) out of the over 1000 ORs encoded in the genome. The expressed OR determines the neuron's selective chemosensory response and specifies its axonal targeting to a particular olfactory glomerulus in the olfactory bulb. Neuronal diversity can also be generated in individual cells by the independent and stochastic expression of autosomal alleles, which leads to functional heterozygosity among neurons. Among the many genes that show autosomal stochastic monoallelic expression, approximately 50 members of the clustered protocadherins (Pcdhs) are stochastically expressed in individual neurons in distinct combinations. The clustered Pcdhs belong to a large subfamily of the cadherin superfamily of homophilic cell-adhesion proteins. Loss-of-function analyses show that the clustered Pcdhs have critical functions in the accuracy of axonal projections, synaptic formation, dendritic arborization, and neuronal survival. In addition, cis-tetramers, composed of heteromultimeric clustered Pcdh members, represent selective binding units for cell-cell interactions, and provide exponential numbers of possible cell-surface relationships between individual neurons. The extensive molecular diversity of neuronal cell-surface proteins affects neurons’ individual properties and connectivities. The molecular features of the diverse clustered Pcdh molecules suggest that they provide a genetic basis for neuronal individuality and appropriate neuronal wiring in the brain.
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Affiliation(s)
- Takeshi Yagi
- KOKORO-Biology Group, Laboratories for Integrated Biology, Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan.
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23
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Weiner JA, Jontes JD. Protocadherins, not prototypical: a complex tale of their interactions, expression, and functions. Front Mol Neurosci 2013; 6:4. [PMID: 23515683 PMCID: PMC3601302 DOI: 10.3389/fnmol.2013.00004] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 03/01/2013] [Indexed: 12/30/2022] Open
Abstract
The organization of functional neural circuits requires the precise and coordinated control of cell-cell interactions at nearly all stages of development, including neuronal differentiation, neuronal migration, axon outgrowth, dendrite arborization, and synapse formation and stabilization. This coordination is brought about by the concerted action of a large number of cell surface receptors, whose dynamic regulation enables neurons (and astrocytes) to adopt their proper roles within developing neural circuits. The protocadherins (Pcdhs) comprise a major family of cell surface receptors expressed in the developing vertebrate nervous system whose cellular and developmental roles are only beginning to be elucidated. In this review, we highlight selected recent results in several key areas of Pcdh biology and discuss their implications for our understanding of neural circuit formation and function.
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Affiliation(s)
- Joshua A Weiner
- Department of Biology, The University of Iowa Iowa City, IA, USA
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24
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Multiple autism-linked genes mediate synapse elimination via proteasomal degradation of a synaptic scaffold PSD-95. Cell 2013; 151:1581-94. [PMID: 23260144 DOI: 10.1016/j.cell.2012.11.040] [Citation(s) in RCA: 219] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Revised: 08/29/2012] [Accepted: 11/20/2012] [Indexed: 01/19/2023]
Abstract
The activity-dependent transcription factor myocyte enhancer factor 2 (MEF2) induces excitatory synapse elimination in mouse neurons, which requires fragile X mental retardation protein (FMRP), an RNA-binding protein implicated in human cognitive dysfunction and autism. We report here that protocadherin 10 (Pcdh10), an autism-spectrum disorders gene, is necessary for this process. MEF2 and FMRP cooperatively regulate the expression of Pcdh10. Upon MEF2 activation, PSD-95 is ubiquitinated by the ubiquitin E3 ligase murine double minute 2 (Mdm2) and then binds to Pcdh10, which links it to the proteasome for degradation. Blockade of the Pcdh10-proteasome interaction inhibits MEF2-induced PSD-95 degradation and synapse elimination. In FMRP-lacking neurons, elevated protein levels of eukaryotic translation elongation factor 1 α (EF1α), an Mdm2-interacting protein and FMRP target mRNA, sequester Mdm2 and prevent MEF2-induced PSD-95 ubiquitination and synapse elimination. Together, our findings reveal roles for multiple autism-linked genes in activity-dependent synapse elimination.
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Hirayama T, Yagi T. Clustered protocadherins and neuronal diversity. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 116:145-67. [PMID: 23481194 DOI: 10.1016/b978-0-12-394311-8.00007-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Neuronal diversity is a fundamental requirement for complex neuronal networks and brain function. The clustered protocadherin (Pcdh) family possesses several characteristic features that are important for the molecular basis of neuronal diversity. Clustered Pcdhs are expressed predominantly in the central nervous system, in neurites, growth cones, and synapses. They consist of about 60 isoforms, and their expression is stochastically and combinatorially regulated in individual neurons. The multiple clustered Pcdhs expressed in individual neurons form heteromultimeric protein complexes that exhibit homophilic adhesion properties. Theoretically, the clustered Pcdhs could generate more than 3×10(10) possible variations in each neuron and 12,720 types of cis-tetramers per neuron. The clustered Pcdhs are important for normal neuronal development. The clustered Pcdh genes have also attracted attention as a target for epigenetic regulation.
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Affiliation(s)
- Teruyoshi Hirayama
- KOKORO Biology Group and JST-CREST, Laboratories for Integrated Biology, Graduate School of Frontier Biosciences, Osaka University, Yamadaoka, Suita, Osaka, Japan
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26
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Abstract
We have found that the γ2 subunit of the GABA(A) receptor (γ2-GABA(A)R) specifically interacts with protocadherin-γC5 (Pcdh-γC5) in the rat brain. The interaction occurs between the large intracellular loop of the γ2-GABA(A)R and the cytoplasmic domain of Pcdh-γC5. In brain extracts, Pcdh-γC5 coimmunoprecipitates with GABA(A)Rs. In cotransfected HEK293 cells, Pcdh-γC5 promotes the transfer of γ2-GABA(A)R to the cell surface. We have previously shown that, in cultured hippocampal neurons, endogenous Pcdh-γC5 forms clusters, some of which associate with GABAergic synapses. Overexpression of Pcdh-γC5 in hippocampal neurons increases the density of γ2-GABA(A)R clusters but has no significant effect on the number of GABAergic contacts that these neurons receive, indicating that Pcdh-γC5 is not synaptogenic. Deletion of the cytoplasmic domain of Pcdh-γC5 enhanced its surface expression but decreased the association with both γ2-GABA(A)R clusters and presynaptic GABAergic contacts. Cultured hippocampal neurons from the Pcdh-γ triple C-type isoform knock-out (TCKO) mouse (Pcdhg(tcko/tcko)) showed plenty of GABAergic synaptic contacts, although their density was reduced compared with sister cultures from wild-type and heterozygous mice. Knocking down Pcdh-γC5 expression with shRNA decreased γ2-GABA(A)R cluster density and GABAergic innervation. The results indicate that, although Pcdh-γC5 is not essential for GABAergic synapse formation or GABA(A)R clustering, (1) Pcdh-γC5 regulates the surface expression of GABA(A)Rs via cis-cytoplasmic interaction with γ2-GABA(A)R, and (2) Pcdh-γC5 plays a role in the stabilization and maintenance of some GABAergic synapses.
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27
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Becker SF, Langhe R, Huang C, Wedlich D, Kashef J. Giving the right tug for migration: Cadherins in tissue movements. Arch Biochem Biophys 2012; 524:30-42. [DOI: 10.1016/j.abb.2012.02.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 02/16/2012] [Accepted: 02/17/2012] [Indexed: 01/01/2023]
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28
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Abstract
Cadherins are Ca(2+)-dependent cell-cell adhesion molecules that play critical roles in animal morphogenesis. Various cadherin-related molecules have also been identified, which show diverse functions, not only for the regulation of cell adhesion but also for that of cell proliferation and planar cell polarity. During the past decade, understanding of the roles of these molecules in the nervous system has significantly progressed. They are important not only for the development of the nervous system but also for its functions and, in turn, for neural disorders. In this review, we discuss the roles of cadherins and related molecules in neural development and function in the vertebrate brain.
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Affiliation(s)
- Shinji Hirano
- Department of Neurobiology and Anatomy, Kochi Medical School, Okoh-cho Kohasu, Nankoku-City 783–8505, Japan.
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29
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Guo H, Nairn A, dela Rosa M, Nagy T, Zhao S, Moremen K, Pierce M. Transcriptional regulation of the protocadherin β cluster during Her-2 protein-induced mammary tumorigenesis results from altered N-glycan branching. J Biol Chem 2012; 287:24941-54. [PMID: 22665489 DOI: 10.1074/jbc.m112.369355] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Changes in the levels of N-acetylglucosaminyltransferase V (GnT-V) can alter the function of several types of cell surface receptors and adhesion molecules by causing altered N-linked glycan branching. Using a her-2 mammary tumor mouse model, her-2 receptor signaling was down-regulated by GnT-V knock-out, resulting in a significant delay in the onset of her-2-induced mammary tumors. To identify the genes that contributed to this GnT-V regulation of early events in tumorigenesis, microarray analysis was performed using her-2 induced mammary tumors from wild-type and GnT-V-null mice. We found that 142 genes were aberrantly expressed (>2.0-fold) with 64 genes up-regulated and 78 genes down-regulated after deletion of GnT-V. Among differentially expressed genes, the expression of a subgroup of the cadherin superfamily, the protocadherin β (Pcdhβ) cluster, was up-regulated in GnT-V-null tumors. Altered expression of the Pcdhβ cluster in GnT-V-null tumors was not due to changes in promoter methylation; instead, impaired her-2-mediated signaling pathways were implicated at least in part resulting from reduced microRNA-21 expression. Overexpression of Pcdhβ genes inhibited tumor cell growth, decreased the proportion of tumor-initiating cells, and decreased tumor formation in vivo, demonstrating that expression of the Pcdhβ gene cluster can serve as an inhibitor of the transformed phenotype. Our results suggest the up-regulation of the Pcdhβ gene cluster as a mechanism for reduced her-2-mediated tumorigenesis resulting from GnT-V deletion.
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Affiliation(s)
- Huabei Guo
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
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Biswas S, Emond MR, Jontes JD. The clustered protocadherins Pcdhα and Pcdhγ form a heteromeric complex in zebrafish. Neuroscience 2012; 219:280-9. [PMID: 22659564 DOI: 10.1016/j.neuroscience.2012.05.058] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 04/26/2012] [Accepted: 05/23/2012] [Indexed: 12/11/2022]
Abstract
The clustered protocadherin genes encode a diverse collection of neuronal cell surface receptors. These genes have been proposed to play roles in axon targeting, synaptic development and neuronal survival, although their specific cellular roles remain poorly defined. In zebrafish there are four clustered protocadherin genes, two pcdhα clusters and two pcdhγ clusters, that give rise to over 100 distinct proteins, each with a distinct ectodomain (EC). The zebrafish is an excellent model in which to address the function of protocadherins during neural development, as the embryos are transparent, develop rapidly, and are amenable to experimental manipulation. As a first step to investigating the clustered protocadherins during zebrafish development, we have generated antibodies against the common cytodomains of zebrafish Pcdhγ. We compare the distribution of Pcdhγ with Pcdhα and find a similar pan-neuronal pattern, with strong labeling of neurons within all major regions of the central nervous system. Pcdhα and Pcdhγ are particularly enriched in the developing visual system, with strong labeling found in the synaptic layers of the retina, as well as the optic tectum. Consistent with studies in mouse, we find that Pcdhα and Pcdhγ are present in a complex, as they can be co-immunoprecipitated from zebrafish larval extracts. This interaction is direct and occurs through the ECs of these proteins. Using standard bead aggregation assays, we find no evidence for intrinsic adhesive ability by either Pcdhγ or Pcdhα, suggesting that they do not function as cell adhesion molecules.
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Affiliation(s)
- S Biswas
- Department of Neuroscience, Ohio State University, Columbus, OH 43210, USA
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Brasch J, Harrison OJ, Honig B, Shapiro L. Thinking outside the cell: how cadherins drive adhesion. Trends Cell Biol 2012; 22:299-310. [PMID: 22555008 DOI: 10.1016/j.tcb.2012.03.004] [Citation(s) in RCA: 242] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 03/19/2012] [Accepted: 03/26/2012] [Indexed: 12/15/2022]
Abstract
Cadherins are a superfamily of cell surface glycoproteins whose ectodomains contain multiple repeats of β-sandwich extracellular cadherin (EC) domains that adopt a similar fold to immunoglobulin domains. The best characterized cadherins are the vertebrate 'classical' cadherins, which mediate adhesion via trans homodimerization between their membrane-distal EC1 domains that extend from apposed cells, and assemble intercellular adherens junctions through cis clustering. To form mature trans adhesive dimers, cadherin domains from apposed cells dimerize in a 'strand-swapped' conformation. This occurs in a two-step binding process involving a fast-binding intermediate called the 'X-dimer'. Trans dimers are less flexible than cadherin monomers, a factor that drives junction assembly following cell-cell contact by reducing the entropic cost associated with the formation of lateral cis oligomers. Cadherins outside the classical subfamily appear to have evolved distinct adhesive mechanisms that are only now beginning to be understood.
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Affiliation(s)
- Julia Brasch
- Department of Biochemistry and Molecular Biophysics, Columbia University, 1150 Saint Nicholas Avenue, New York, NY 10032, USA
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32
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Dunne E, Spring CM, Reheman A, Jin W, Berndt MC, Newman DK, Newman PJ, Ni H, Kenny D. Cadherin 6 has a functional role in platelet aggregation and thrombus formation. Arterioscler Thromb Vasc Biol 2012; 32:1724-31. [PMID: 22539596 DOI: 10.1161/atvbaha.112.250464] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
OBJECTIVE Thrombosis occurs at sites of vascular injury when platelets adhere to subendothelial matrix proteins and to each other. Platelets express many surface receptor proteins, the function of several of these remains poorly characterized. Cadherin 6 is expressed on the platelet surface and contains an arginine-glycine-aspartic acid motif, suggesting that it might have a supportive role in thrombus formation. The aim of this study was to characterize the role of cadherin 6 in platelet function. METHODS AND RESULTS Platelet aggregation was inhibited by both antibodies and exogenous soluble cadherin 6. Platelet adhesion to immobilized cadherin 6 was inhibited by arginine-glycine-aspartic acid-serine tetrapeptides. Antibodies to α(IIb)β(3) inhibited platelet adhesion to cadherin 6. Because platelet aggregation occurs in fibrinogen and von Willebrand factor double-deficient mice, we investigated whether cadherin 6 is an alternative ligand for the integrin α(IIb)β(3). Platelet aggregation in fibrinogen and von Willebrand factor double-deficient mice was significantly inhibited by an antibody to cadherin 6. In flow-based assays, inhibition of cadherin 6 caused a marked reduction in thrombus formation in both human and mouse blood. CONCLUSIONS This study demonstrates the role of cadherin 6 as a novel ligand for α(IIb)β(3) and highlights its function in thrombus formation.
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Affiliation(s)
- Eimear Dunne
- Royal College of Surgeons in Ireland, Dublin, Ireland
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Yagi T. Molecular codes for neuronal individuality and cell assembly in the brain. Front Mol Neurosci 2012; 5:45. [PMID: 22518100 PMCID: PMC3324988 DOI: 10.3389/fnmol.2012.00045] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2012] [Accepted: 03/22/2012] [Indexed: 11/13/2022] Open
Abstract
The brain contains an enormous, but finite, number of neurons. The ability of this limited number of neurons to produce nearly limitless neural information over a lifetime is typically explained by combinatorial explosion; that is, by the exponential amplification of each neuron's contribution through its incorporation into "cell assemblies" and neural networks. In development, each neuron expresses diverse cellular recognition molecules that permit the formation of the appropriate neural cell assemblies to elicit various brain functions. The mechanism for generating neuronal assemblies and networks must involve molecular codes that give neurons individuality and allow them to recognize one another and join appropriate networks. The extensive molecular diversity of cell-surface proteins on neurons is likely to contribute to their individual identities. The clustered protocadherins (Pcdh) is a large subfamily within the diverse cadherin superfamily. The clustered Pcdh genes are encoded in tandem by three gene clusters, and are present in all known vertebrate genomes. The set of clustered Pcdh genes is expressed in a random and combinatorial manner in each neuron. In addition, cis-tetramers composed of heteromultimeric clustered Pcdh isoforms represent selective binding units for cell-cell interactions. Here I present the mathematical probabilities for neuronal individuality based on the random and combinatorial expression of clustered Pcdh isoforms and their formation of cis-tetramers in each neuron. Notably, clustered Pcdh gene products are known to play crucial roles in correct axonal projections, synaptic formation, and neuronal survival. Their molecular and biological features induce a hypothesis that the diverse clustered Pcdh molecules provide the molecular code by which neuronal individuality and cell assembly permit the combinatorial explosion of networks that supports enormous processing capability and plasticity of the brain.
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Affiliation(s)
- Takeshi Yagi
- KOKORO-Biology Group, Graduate School of Frontier Biosciences, Laboratories for Integrated Biology, Osaka University, Yamadaoka, Suita Osaka, Japan
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Emond MR, Biswas S, Blevins CJ, Jontes JD. A complex of Protocadherin-19 and N-cadherin mediates a novel mechanism of cell adhesion. ACTA ACUST UNITED AC 2011; 195:1115-21. [PMID: 22184198 PMCID: PMC3246890 DOI: 10.1083/jcb.201108115] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
During embryonic morphogenesis, adhesion molecules are required for selective cell-cell interactions. The classical cadherins mediate homophilic calcium-dependent cell adhesion and are founding members of the large and diverse cadherin superfamily. The protocadherins are the largest subgroup within this superfamily, yet their participation in calcium-dependent cell adhesion is uncertain. In this paper, we demonstrate a novel mechanism of adhesion, mediated by a complex of Protocadherin-19 (Pcdh19) and N-cadherin (Ncad). Although Pcdh19 alone is only weakly adhesive, the Pcdh19-Ncad complex exhibited robust adhesion in bead aggregation assays, and Pcdh19 appeared to play the dominant role. Adhesion by the Pcdh19-Ncad complex was unaffected by mutations that disrupt Ncad homophilic binding but was inhibited by a mutation in Pcdh19. In addition, the complex exhibited homophilic specificity, as beads coated with Pcdh19-Ncad did not intermix with Ncad- or Pcdh17-Ncad-coated beads. We propose a model in which association of a protocadherin with Ncad acts as a switch, converting between distinct binding specificities.
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Affiliation(s)
- Michelle R Emond
- Department of Neuroscience, School of Biomedical Science, The Ohio State University, Columbus, OH 43210, USA
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Blevins CJ, Emond MR, Biswas S, Jontes JD. Differential expression, alternative splicing, and adhesive properties of the zebrafish δ1-protocadherins. Neuroscience 2011; 199:523-34. [PMID: 22001682 DOI: 10.1016/j.neuroscience.2011.09.061] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 09/11/2011] [Accepted: 09/22/2011] [Indexed: 12/16/2022]
Abstract
Protocadherins comprise the largest family within the cadherin superfamily of cell surface receptors. Here, we characterize the δ1-protocadherin subfamily during the development of the zebrafish nervous system. In zebrafish, there are five δ1-protocadherins: pcdh1a, pcdh1b, pcdh7a, pcdh7b, andpcdh9. Each protocadherin gene is highly homologous to its human ortholog. While the expression pattern in the developing CNS is similar for each δ1-protocadherin, with labeling observed in all major subdivisions, the detailed patterns are distinct. In addition, we provide evidence for alternative splicing of the pcdh7b and pcdh9 genes, resulting in variation in their respective cytoplasmic domains. As protocadherins are widely regarded to act as cell adhesion molecules, we used in vitro assays of δ1-pcdh ectodomains to directly test their adhesive properties. We found no evidence for calcium-dependent, homophilic adhesion, contrasting sharply with the behavior of classical cadherins.
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Affiliation(s)
- C J Blevins
- Department of Neuroscience, Ohio State University Medical Center, Columbus, OH 43210, USA
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Zipursky SL, Sanes JR. Chemoaffinity revisited: dscams, protocadherins, and neural circuit assembly. Cell 2010; 143:343-53. [PMID: 21029858 DOI: 10.1016/j.cell.2010.10.009] [Citation(s) in RCA: 229] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 09/24/2010] [Accepted: 10/06/2010] [Indexed: 12/11/2022]
Abstract
The chemoaffinity hypothesis for neural circuit assembly posits that axons and their targets bear matching molecular labels that endow neurons with unique identities and specify synapses between appropriate partners. Here, we focus on two intriguing candidates for fulfilling this role, Drosophila Dscams and vertebrate clustered protocadherins (Pcdhs). In each, a complex genomic locus encodes large numbers of neuronal transmembrane proteins with homophilic binding specificity, individual members of which are expressed combinatorially. Although these properties suggest that Dscams and Pcdhs could act as specificity molecules, they may do so in ways that challenge traditional views of how neural circuits assemble.
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Affiliation(s)
- S Lawrence Zipursky
- Department of Biological Chemistry, Howard Hughes Medical Institute, University of California, Los Angeles, 90095, USA.
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Abstract
Synaptic junctions are generated by adhesion proteins that bridge the synaptic cleft to firmly anchor pre- and postsynaptic membranes. Several cell adhesion molecule (CAM) families localize to synapses, but it is not yet completely understood how each synaptic CAM family contributes to synapse formation and/or structure, and whether or how smaller groups of CAMs serve as minimal, functionally cooperative adhesive units upon which structure is based. Synapse structure and function evolve over the course of development, and in mature animals, synapses are composed of a greater number of proteins, surrounded by a stabilizing extracellular matrix, and often contacted by astrocytic processes. Thus, in mature networks undergoing plasticity, persistent changes in synapse strength, morphology, or number must be accompanied by selective and regulated remodeling of the neuropil. Recent work indicates that regulated, extracellular proteolysis may be essential for this, and rather than simply acting permissively to enable synapse plasticity, is more likely playing a proactive role in driving coordinated synaptic structural and functional modifications that underlie persistent changes in network activity.
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Affiliation(s)
- Deanna L Benson
- Fishberg Department of Neuroscience and Friedman Brain Institute, Mount Sinai School of Medicine, New York, New York 10029, USA.
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Proteolytic processing of protocadherin proteins requires endocytosis. Proc Natl Acad Sci U S A 2010; 107:17774-9. [PMID: 20876099 DOI: 10.1073/pnas.1013105107] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The α-, β-, and γ-protocadherins (Pcdhα, Pcdhβ, and Pcdhγ) comprise a large family of single-pass transmembrane proteins predominantly expressed in the nervous system. These proteins contain six cadherin-like extracellular domains, and proteolysis of Pcdhα and Pcdhγ by the γ-secretase complex releases their intracellular domains into the cytoplasm where they may function locally and/or enter the nucleus and affect gene expression. Thus, cleavage of Pcdhs may function to link intercellular contacts and intracellular signaling. Here we report that shedding of the Pcdhα extracellular domain and subsequent processing by γ-secretase require endocytosis and that Pcdhs interact with the regulator of vesicular sorting ESCRT-0 in undifferentiated cells. We also find that the accumulation of Pcdh cleavage products is regulated during development. Differentiation leads to an increase in the interactions between Pcdh proteins and a decrease in the accumulation of cleavage products. We conclude that Pcdh processing requires endocytosis and that the level of cleavage products is regulated during neuronal differentiation.
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Fernández-Monreal M, Oung T, Hanson HH, O'Leary R, Janssen WG, Dolios G, Wang R, Phillips GR. γ-protocadherins are enriched and transported in specialized vesicles associated with the secretory pathway in neurons. Eur J Neurosci 2010; 32:921-31. [PMID: 20849527 DOI: 10.1111/j.1460-9568.2010.07386.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Gamma protocadherins (Pcdh-γs) resemble classical cadherins and have the potential to engage in cell-cell interactions with homophilic properties. Emerging evidence suggests non-conventional roles for some protocadherins in neural development. We sought to determine whether Pcdh-γ trafficking in neurons is consistent with an intracellular role for these molecules. Here we show that, in contrast to the largely surface localization of classical cadherins, endogenous Pcdh-γs are primarily intracellular in rat neurons in vivo and are equally distributed within organelles of subsynaptic dendritic and axonal compartments. A strikingly higher proportion of Pcdh-γ-containing organelles in synaptic compartments was observed at postnatal day 16. To determine the origin of Pcdh-γ-trafficking organelles, we isolated organelles with Pcdh-γ antibody-coupled magnetic beads from brain organelle suspensions. Vesicles with high levels of COPII and endoplasmic reticulum-Golgi intermediate compartment (ERGIC) components were isolated with the Pcdh-γ antibody but not with the classical cadherin antibody. In cultured hippocampal neurons, Pcdh-γ immunolabeling partially overlapped with calnexin- and COPII-positive puncta in dendrites. Mobile Pcdh-γ-GFP profiles dynamically codistributed with a DsRed construct coupled to ER retention signals by live imaging. Pcdh-γ expression correlated with accumulations of tubulovesicular and ER-like organelles in dendrites. Our results are consistent with the possibility that Pcdh-γs could have a unique function within the secretory pathway in addition to their documented surface roles.
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Ostergaard E, Batbayli M, Duno M, Vilhelmsen K, Rosenberg T. Mutations in PCDH21 cause autosomal recessive cone-rod dystrophy. J Med Genet 2010; 47:665-9. [PMID: 20805371 PMCID: PMC2976051 DOI: 10.1136/jmg.2009.069120] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Background Cone-rod dystrophy is a retinal dystrophy with early loss of cone photoreceptors and a parallel or subsequent loss of rod photoreceptors. It may be syndromic, but most forms are non-syndromic with autosomal dominant, autosomal recessive or X-linked recessive inheritance. Methods and results We identified a small consanguineous family with six patients with cone-rod dystrophy from the Faroe Islands. Homozygosity mapping revealed a single homozygous locus of 4.2 Mb on chromosome 10q23.1–q23.2, encompassing 11 genes. All patients were homozygous for a 1-bp duplication in PCDH21, c.524dupA, which results in a frameshift and a premature stop codon (p.Q175QfsX47). Conclusion To our knowledge, this is the first report of mutations in PCDH21 as a cause of human disease. PCDH21 is highly expressed in the retinal photoreceptor cells. It encodes protocadherin 21, which belongs to the cadherin superfamily of large cell surface proteins characterised by a variable number of extracellular cadherin domains. A PCDH21 knockout mouse model has previously shown loss of photoreceptor cells and abnormal cone and rod function, similar to the findings in the patients.
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Affiliation(s)
- E Ostergaard
- Department of Clinical Genetics 4062, National University Hospital Rigshospitalet, Blegdamsvej 9, Copenhagen 2100, Denmark.
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41
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Combinatorial homophilic interaction between gamma-protocadherin multimers greatly expands the molecular diversity of cell adhesion. Proc Natl Acad Sci U S A 2010; 107:14893-8. [PMID: 20679223 DOI: 10.1073/pnas.1004526107] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The specificity of interactions between neurons is believed to be mediated by diverse cell adhesion molecules, including members of the cadherin superfamily. Whereas mechanisms of classical cadherin adhesion have been studied extensively, much less is known about the related protocadherins (Pcdhs), which together make up the majority of the superfamily. Here we use quantitative cell aggregation assays and biochemical analyses to characterize cis and trans interactions among the 22-member gamma-Pcdh family, which have been shown to be critical for the control of synaptogenesis and neuronal survival. We show that gamma-Pcdh isoforms engage in trans interactions that are strictly homophilic. In contrast to classical cadherins, gamma-Pcdh interactions are only partially Ca(2+)-dependent, and their specificity is mediated through the second and third extracellular cadherin (EC) domains (EC2 and EC3), rather than through EC1. The gamma-Pcdhs also interact both covalently and noncovalently in the cis-orientation to form multimers both in vitro and in vivo. In contrast to gamma-Pcdh trans interactions, cis interactions are highly promiscuous, with no isoform specificity. We present data supporting a model in which gamma-Pcdh cis-tetramers represent the unit of their adhesive trans interactions. Unrestricted tetramerization in cis, coupled with strictly homophilic interactions in trans, predicts that the 22 gamma-Pcdhs could form 234,256 distinct adhesive interfaces. Given the demonstrated role of the gamma-Pcdhs in synaptogenesis, our data have important implications for the molecular control of neuronal specificity.
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Hanson HH, Kang S, Fernández-Monreal M, Oung T, Yildirim M, Lee R, Suyama K, Hazan RB, Phillips GR. LC3-dependent intracellular membrane tubules induced by gamma-protocadherins A3 and B2: a role for intraluminal interactions. J Biol Chem 2010; 285:20982-92. [PMID: 20439459 DOI: 10.1074/jbc.m109.092031] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Clustered protocadherins (Pcdhs) are a family of cadherin-like molecules arranged in gene clusters (alpha, beta, and gamma). gamma-Protocadherins (Pcdh-gammas) are involved in cell-cell interactions, but their prominent intracellular distribution in vivo and different knock-out phenotypes suggest that these molecules participate in still unidentified processes. We found using correlative light and electron microscopy that Pcdh-gammaA3 and -gammaB2, but not -gammaC4, -alpha1, or N-cadherin, generate intracellular juxtanuclear membrane tubules when expressed in cells. These tubules recruit the autophagy marker MAP1A/1B LC3 (LC3) but are not associated with autophagic vesicles. Lipidation of LC3 is required for its coclustering with Pcdh-gamma tubules, suggesting the involvement of an autophagic-like molecular cascade. Expression of wild-type LC3 with Pcdh-gammaA3 increased tubule length whereas expression of lipidation-defective LC3 decreased tubule length relative to Pcdh-gammaA3 expressed alone. The tubules were found to emanate from lysosomes. Deletion of the luminal/extracellular domain of Pcdh-gammaA3 preserved lysosomal targeting but eliminated tubule formation whereas cytoplasmic deletion eliminated both lysosomal targeting and tubule formation. Deletion of the membrane-proximal three cadherin repeats resulted in tubes that were narrower than those produced by full-length molecules. These results suggest that Pcdh-gammaA and -gammaB families can influence the shape of intracellular membranes by mediating intraluminal interactions within organelles.
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Affiliation(s)
- Hugo H Hanson
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY 10029, USA
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Jiang XJ, Li S, Ravi V, Venkatesh B, Yu WP. Identification and comparative analysis of the protocadherin cluster in a reptile, the green anole lizard. PLoS One 2009; 4:e7614. [PMID: 19898614 PMCID: PMC2764143 DOI: 10.1371/journal.pone.0007614] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2009] [Accepted: 10/06/2009] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The vertebrate protocadherins are a subfamily of cell adhesion molecules that are predominantly expressed in the nervous system and are believed to play an important role in establishing the complex neural network during animal development. Genes encoding these molecules are organized into a cluster in the genome. Comparative analysis of the protocadherin subcluster organization and gene arrangements in different vertebrates has provided interesting insights into the history of vertebrate genome evolution. Among tetrapods, protocadherin clusters have been fully characterized only in mammals. In this study, we report the identification and comparative analysis of the protocadherin cluster in a reptile, the green anole lizard (Anolis carolinensis). METHODOLOGY/PRINCIPAL FINDINGS We show that the anole protocadherin cluster spans over a megabase and encodes a total of 71 genes. The number of genes in the anole protocadherin cluster is significantly higher than that in the coelacanth (49 genes) and mammalian (54-59 genes) clusters. The anole protocadherin genes are organized into four subclusters: the delta, alpha, beta and gamma. This subcluster organization is identical to that of the coelacanth protocadherin cluster, but differs from the mammalian clusters which lack the delta subcluster. The gene number expansion in the anole protocadherin cluster is largely due to the extensive gene duplication in the gammab subgroup. Similar to coelacanth and elephant shark protocadherin genes, the anole protocadherin genes have experienced a low frequency of gene conversion. CONCLUSIONS/SIGNIFICANCE Our results suggest that similar to the protocadherin clusters in other vertebrates, the evolution of anole protocadherin cluster is driven mainly by lineage-specific gene duplications and degeneration. Our analysis also shows that loss of the protocadherin delta subcluster in the mammalian lineage occurred after the divergence of mammals and reptiles. We present a model for the evolutionary history of the protocadherin cluster in tetrapods.
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Affiliation(s)
- Xiao-Juan Jiang
- Gene Regulation Laboratory, National Neuroscience Institute, Singapore, Singapore
- School of Life Sciences, Shandong University, Jinan, China
| | - Shaobing Li
- Gene Regulation Laboratory, National Neuroscience Institute, Singapore, Singapore
| | - Vydianathan Ravi
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Byrappa Venkatesh
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Wei-Ping Yu
- Gene Regulation Laboratory, National Neuroscience Institute, Singapore, Singapore
- * E-mail:
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Protocadherin-alpha family is required for serotonergic projections to appropriately innervate target brain areas. J Neurosci 2009; 29:9137-47. [PMID: 19625505 DOI: 10.1523/jneurosci.5478-08.2009] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Serotonergic axons from the raphe nuclei in the brainstem project to every region of the brain, where they make connections through their extensive terminal arborizations. This serotonergic innervation contributes to various normal behaviors and psychiatric disorders. The protocadherin-alpha (Pcdha) family of clustered protocadherins consists of 14 cadherin-related molecules generated from a single gene cluster. We found that the Pcdhas were strongly expressed in the serotonergic neurons. To elucidate their roles, we examined serotonergic fibers in a mouse mutant (Pcdha(Delta CR/Delta CR)) lacking the Pcdha cytoplasmic region-encoding exons, which are common to the gene cluster. In the first week after birth, the distribution pattern of serotonergic fibers in Pcdha(Delta CR/Delta CR) mice was similar to wild-type, but by 3 weeks of age, when the serotonergic axonal termini complete their arborizations, the distribution of the projections was abnormal. In some target regions, notably the globus pallidus and substantia nigra, the normally even distribution of serotonin axonal terminals was, in the mutants, dense at the periphery of each region, but sparse in the center. In the stratum lacunosum-molecular of the hippocampus, the mutants showed denser serotonergic innervation than in wild-type, and in the dentate gyrus of the hippocampus and the caudate-putamen, the innervation was sparser. Together, the abnormalities suggested that Pcdha proteins are important in the late-stage maturation of serotonergic projections. Further examination of alternatively spliced exons encoding the cytoplasmic tail showed that the A-type (but not the B-type) cytoplasmic tail was essential for the normal development of serotonergic projections.
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Emond MR, Biswas S, Jontes JD. Protocadherin-19 is essential for early steps in brain morphogenesis. Dev Biol 2009; 334:72-83. [PMID: 19615992 DOI: 10.1016/j.ydbio.2009.07.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2009] [Revised: 07/02/2009] [Accepted: 07/08/2009] [Indexed: 10/20/2022]
Abstract
One of the earliest stages of brain morphogenesis is the establishment of the neural tube during neurulation. While some of the cellular mechanisms responsible for neurulation have been described in a number of vertebrate species, the underlying molecular processes are not fully understood. We have identified the zebrafish homolog of protocadherin-19, a member of the cadherin superfamily, which is expressed in the anterior neural plate and is required for brain morphogenesis. Interference with Protocadherin-19 function with antisense morpholino oligonucleotides leads to a severe disruption in early brain morphogenesis. Despite these pronounced effects on neurulation, axial patterning of the neural tube appears normal, as assessed by in situ hybridization for otx2, pax2.1 and krox20. Characterization of embryos early in development by in vivo 2-photon timelapse microscopy reveals that the observed disruption of morphogenesis results from an arrest of cell convergence in the anterior neural plate. These results provide the first functional data for protocadherin-19, demonstrating an essential role in early brain development.
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Affiliation(s)
- Michelle R Emond
- Center for Molecular Neurobiology and Department of Neuroscience, 115 Rightmire Hall, Ohio State University, Columbus, OH 43210, USA
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46
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Fernández-Monreal M, Kang S, Phillips GR. Gamma-protocadherin homophilic interaction and intracellular trafficking is controlled by the cytoplasmic domain in neurons. Mol Cell Neurosci 2008; 40:344-53. [PMID: 19136062 DOI: 10.1016/j.mcn.2008.12.002] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 11/26/2008] [Accepted: 12/01/2008] [Indexed: 11/19/2022] Open
Abstract
Gamma-protocadherins (Pcdh-gammas) are good candidates to mediate specificity in synaptogenesis but their role in cell-cell interactions is a matter of debate. We proposed that Pcdh-gammas modify preformed synapses via trafficking of Pcdh-gammas-containing organelles, insertion into synaptic membranes and homophilic transcellular interaction. Here we provide evidence in support of this model. We show for the first time that Pcdh-gammas have homophilic properties and that they accumulate at dendro-dendritic and axo-dendritic interfaces during neuronal development. Pcdh-gammas are maintained in a substantial mobile intracellular pool in dendrites and cytoplasmic deletion shifts the molecule to the surface and reduces the number and velocity of the mobile packets. We monitored Pcdh-gamma temporal and spatial dynamics in transport organelles. Pcdh-gamma organelles bud and fuse with stationary clusters near synapses. These results suggest that Pcdh-gamma-mediated cell-cell interactions in synapse development or maintenance are tightly regulated by control of intracellular trafficking via the cytoplasmic domain.
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Hulpiau P, van Roy F. Molecular evolution of the cadherin superfamily. Int J Biochem Cell Biol 2008; 41:349-69. [PMID: 18848899 DOI: 10.1016/j.biocel.2008.09.027] [Citation(s) in RCA: 305] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 09/19/2008] [Accepted: 09/24/2008] [Indexed: 02/02/2023]
Abstract
This review deals with the large and pleiotropic superfamily of cadherins and its molecular evolution. We compiled literature data and an in-depth phylogenetic analysis of more than 350 members of this superfamily from about 30 species, covering several but not all representative branches within metazoan evolution. We analyzed the sequence homology between either ectodomains or cytoplasmic domains, and we reviewed protein structural data and genomic architecture. Cadherins and cadherin-related molecules are defined by having an ectodomain in which at least two consecutive calcium-binding cadherin repeats are present. There are usually 5 or 6 domains, but in some cases as many as 34. Additional protein modules in the ectodomains point at adaptive evolution. Despite the occurrence of several conserved motifs in subsets of cytoplasmic domains, these domains are even more diverse than ectodomains and most likely have evolved separately from the ectodomains. By fine tuning molecular classifications, we reduced the number of solitary superfamily members. We propose a cadherin major branch, subdivided in two families and 8 subfamilies, and a cadherin-related major branch, subdivided in four families and 11 subfamilies. Accordingly, we propose a more appropriate nomenclature. Although still fragmentary, our insight into the molecular evolution of these remarkable proteins is steadily growing. Consequently, we can start to propose testable hypotheses for structure-function relationships with impact on our models of molecular evolution. An emerging concept is that the ever evolving diversity of cadherin structures is serving dual and important functions: specific cell adhesion and intricate cell signaling.
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Affiliation(s)
- Paco Hulpiau
- Department for Molecular Biomedical Research, VIB, Ghent, Belgium
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48
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Fukuda E, Hamada S, Hasegawa S, Katori S, Sanbo M, Miyakawa T, Yamamoto T, Yamamoto H, Hirabayashi T, Yagi T. Down-regulation of protocadherin-α A isoforms in mice changes contextual fear conditioning and spatial working memory. Eur J Neurosci 2008; 28:1362-76. [DOI: 10.1111/j.1460-9568.2008.06428.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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49
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Pedrosa E, Stefanescu R, Margolis B, Petruolo O, Lo Y, Nolan K, Novak T, Stopkova P, Lachman HM. Analysis of protocadherin alpha gene enhancer polymorphism in bipolar disorder and schizophrenia. Schizophr Res 2008; 102:210-9. [PMID: 18508241 PMCID: PMC2862380 DOI: 10.1016/j.schres.2008.04.013] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Revised: 04/07/2008] [Accepted: 04/10/2008] [Indexed: 02/06/2023]
Abstract
Cadherins and protocadherins are cell adhesion proteins that play an important role in neuronal migration, differentiation and synaptogenesis, properties that make them targets to consider in schizophrenia (SZ) and bipolar disorder (BD) pathogenesis. Consequently, allelic variation occurring in protocadherin and cadherin encoding genes that map to regions of the genome targeted in SZ and BD linkage studies are particularly strong candidates to consider. One such set of candidate genes is the 5q31-linked PCDH family, which consists of more than 50 exons encoding three related, though distinct family members--alpha, beta, and gamma--which can generate thousands of different protocadherin proteins through alternative promoter usage and cis-alternative splicing. In this study, we focused on a SNP, rs31745, which is located in a putative PCDHalpha enhancer mapped by ChIP-chip using antibodies to covalently modified histone H3. A striking increase in homozygotes for the minor allele at this locus was detected in patients with BD. Molecular analysis revealed that the SNP causes allele-specific changes in binding to a brain protein. The findings suggest that the 5q31-linked PCDH locus should be more thoroughly considered as a disease-susceptibility locus in psychiatric disorders.
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Affiliation(s)
- Erika Pedrosa
- Department of Psychiatry and Behavioral Sciences, Division of Basic Research, Albert Einstein College of Medicine, Bronx, New York
| | - Radu Stefanescu
- Department of Psychiatry and Behavioral Sciences, Division of Basic Research, Albert Einstein College of Medicine, Bronx, New York
| | - Benjamin Margolis
- Department of Psychiatry and Behavioral Sciences, Division of Basic Research, Albert Einstein College of Medicine, Bronx, New York
| | - Oriana Petruolo
- Department of Psychiatry and Behavioral Sciences, Division of Basic Research, Albert Einstein College of Medicine, Bronx, New York
| | - Yungtai Lo
- Department of Epidemiology and Population Health Montefiore Medical Center, Albert Einstein College of Medicine
| | - Karen Nolan
- Department of Psychiatry, Nathan Kline Institute, Orangeburg, New York
| | - Tomas Novak
- Prague Psychiatric Center, Prague, Czech Republic
| | | | - Herbert M. Lachman
- Department of Psychiatry and Behavioral Sciences, Division of Basic Research, Albert Einstein College of Medicine, Bronx, New York
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Emond MR, Jontes JD. Inhibition of protocadherin-alpha function results in neuronal death in the developing zebrafish. Dev Biol 2008; 321:175-87. [PMID: 18602383 DOI: 10.1016/j.ydbio.2008.06.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 06/05/2008] [Accepted: 06/05/2008] [Indexed: 01/10/2023]
Abstract
The pcdhalpha/CNR gene comprises a diverse array of neuronal cell-surface proteins of the cadherin superfamily, although very little is known about their role in neural development. Here we provide the first in-depth characterization of pcdh1alpha in zebrafish. Whole-mount immunocytochemistry demonstrates that a large proportion of endogenous cytoplasmic domain immunoreactivity is present in the nucleus, suggesting that endoproteolytic cleavage and nuclear translocation of the intracellular domain are important aspects of pcdh1alpha activity in vivo. Using whole-mount immunocytochemistry and BAC-based expression of Pcdh1alpha-GFP fusion proteins, we find that Pcdh1alpha does not appear to form stable, synaptic puncta at early stages of synaptogenesis. We also demonstrate that the presence of the Pcdh1alpha cytoplasmic domain is essential for normal function. Truncation of Pcdh1alpha proteins, using splice-blocking antisense morpholinos to prevent the addition of the common intracellular domain to the entire pcdh1alpha cluster, results in neuronal apoptosis throughout the developing brain and spinal cord, demonstrating an essential role for pcdh1alpha in early neural development. This cell death phenotype can be attenuated by the expression of a soluble Pcdh1alpha cytoplasmic domain.
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Affiliation(s)
- Michelle R Emond
- Center for Molecular Neurobiology and Department of Neuroscience, 115 Rightmire Hall, 1060 Carmack Road, The Ohio State University Medical Center, Columbus, OH 43210, USA
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