1
|
Chowdhury D, Watters K, Biederer T. Synaptic recognition molecules in development and disease. Curr Top Dev Biol 2021; 142:319-370. [PMID: 33706921 DOI: 10.1016/bs.ctdb.2020.12.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Synaptic connectivity patterns underlie brain functions. How recognition molecules control where and when neurons form synapses with each other, therefore, is a fundamental question of cellular neuroscience. This chapter delineates adhesion and signaling complexes as well as secreted factors that contribute to synaptic partner recognition in the vertebrate brain. The sections follow a developmental perspective and discuss how recognition molecules (1) guide initial synaptic wiring, (2) provide for the rejection of incorrect partner choices, (3) contribute to synapse specification, and (4) support the removal of inappropriate synapses once formed. These processes involve a rich repertoire of molecular players and key protein families are described, notably the Cadherin and immunoglobulin superfamilies, Semaphorins/Plexins, Leucine-rich repeat containing proteins, and Neurexins and their binding partners. Molecular themes that diversify these recognition systems are defined and highlighted throughout the text, including the neuron-type specific expression and combinatorial action of recognition factors, alternative splicing, and post-translational modifications. Methodological innovations advancing the field such as proteomic approaches and single cell expression studies are additionally described. Further, the chapter highlights the importance of choosing an appropriate brain region to analyze synaptic recognition factors and the advantages offered by laminated structures like the hippocampus or retina. In a concluding section, the profound disease relevance of aberrant synaptic recognition for neurodevelopmental and psychiatric disorders is discussed. Based on the current progress, an outlook is presented on research goals that can further advance insights into how recognition molecules provide for the astounding precision and diversity of synaptic connections.
Collapse
Affiliation(s)
| | - Katherine Watters
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States; Neuroscience Graduate Program, Tufts University School of Medicine, Boston, MA, United States
| | - Thomas Biederer
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States.
| |
Collapse
|
2
|
Yumoto T, Kimura M, Nagatomo R, Sato T, Utsunomiya S, Aoki N, Kitaura M, Takahashi K, Takemoto H, Watanabe H, Okano H, Yoshida F, Nao Y, Tomita T. Autism-associated variants of neuroligin 4X impair synaptogenic activity by various molecular mechanisms. Mol Autism 2020; 11:68. [PMID: 32873342 PMCID: PMC7465329 DOI: 10.1186/s13229-020-00373-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 08/20/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Several genetic alterations, including point mutations and copy number variations in NLGN genes, have been associated with psychiatric disorders, such as autism spectrum disorder (ASD) and X-linked mental retardation (XLMR). NLGN genes encode neuroligin (NL) proteins, which are adhesion molecules that are important for proper synaptic formation and maturation. Previously, we and others found that the expression level of murine NL1 is regulated by proteolytic processing in a synaptic activity-dependent manner. METHODS In this study, we analyzed the effects of missense variants associated with ASD and XLMR on the metabolism and function of NL4X, a protein which is encoded by the NLGN4X gene and is expressed only in humans, using cultured cells, primary neurons from rodents, and human induced pluripotent stem cell-derived neurons. RESULTS NL4X was found to undergo proteolytic processing in human neuronal cells. Almost all NL4X variants caused a substantial decrease in the levels of mature NL4X and its synaptogenic activity in a heterologous culture system. Intriguingly, the L593F variant of NL4X accelerated the proteolysis of mature NL4X proteins located on the cell surface. In contrast, other variants decreased the cell-surface trafficking of NL4X. Notably, protease inhibitors as well as chemical chaperones rescued the expression of mature NL4X. LIMITATIONS Our study did not reveal whether these dysfunctional phenotypes occurred in individuals carrying NLGN4X variant. Moreover, though these pathological mechanisms could be exploited as potential drug targets for ASD, it remains unclear whether these compounds would have beneficial effects on ASD model animals and patients. CONCLUSIONS These data suggest that reduced amounts of the functional NL4X protein on the cell surface is a common mechanism by which point mutants of the NL4X protein cause psychiatric disorders, although different molecular mechanisms are thought to be involved. Furthermore, these results highlight that the precision medicine approach based on genetic and cell biological analyses is important for the development of therapeutics for psychiatric disorders.
Collapse
Affiliation(s)
- Takafumi Yumoto
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Misaki Kimura
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Ryota Nagatomo
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Tsukika Sato
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan
| | - Shun Utsunomiya
- Neuroscience 2, Laboratory for Drug Discovery and Disease Research, Shionogi, Osaka, Japan
- Business-Academia Collaborative Laboratory (Shionogi), Graduate School of Pharmaceutical Science, The University of Tokyo, Tokyo, Japan
| | - Natsue Aoki
- Neuroscience 2, Laboratory for Drug Discovery and Disease Research, Shionogi, Osaka, Japan
- Business-Academia Collaborative Laboratory (Shionogi), Graduate School of Pharmaceutical Science, The University of Tokyo, Tokyo, Japan
| | - Motoji Kitaura
- Research Administration SPRC, R&D General Administration Unit, General Administration Division, Shionogi Administration Service, Osaka, Japan
| | - Koji Takahashi
- Drug Discovery Technology 3, Laboratory for Innovative Therapy Research, Shionogi, Osaka, Japan
| | - Hiroshi Takemoto
- Neuroscience 2, Laboratory for Drug Discovery and Disease Research, Shionogi, Osaka, Japan
- Business-Academia Collaborative Laboratory (Shionogi), Graduate School of Pharmaceutical Science, The University of Tokyo, Tokyo, Japan
| | - Hirotaka Watanabe
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan
| | - Hideyuki Okano
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan
| | - Fumiaki Yoshida
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Yosuke Nao
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Taisuke Tomita
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
| |
Collapse
|
3
|
Banerjee S, Riordan M, Bhat MA. Genetic aspects of autism spectrum disorders: insights from animal models. Front Cell Neurosci 2014; 8:58. [PMID: 24605088 PMCID: PMC3932417 DOI: 10.3389/fncel.2014.00058] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 02/07/2014] [Indexed: 01/26/2023] Open
Abstract
Autism spectrum disorders (ASDs) are a complex neurodevelopmental disorder that display a triad of core behavioral deficits including restricted interests, often accompanied by repetitive behavior, deficits in language and communication, and an inability to engage in reciprocal social interactions. ASD is among the most heritable disorders but is not a simple disorder with a singular pathology and has a rather complex etiology. It is interesting to note that perturbations in synaptic growth, development, and stability underlie a variety of neuropsychiatric disorders, including ASD, schizophrenia, epilepsy, and intellectual disability. Biological characterization of an increasing repertoire of synaptic mutants in various model organisms indicates synaptic dysfunction as causal in the pathophysiology of ASD. Our understanding of the genes and genetic pathways that contribute toward the formation, stabilization, and maintenance of functional synapses coupled with an in-depth phenotypic analysis of the cellular and behavioral characteristics is therefore essential to unraveling the pathogenesis of these disorders. In this review, we discuss the genetic aspects of ASD emphasizing on the well conserved set of genes and genetic pathways implicated in this disorder, many of which contribute to synapse assembly and maintenance across species. We also review how fundamental research using animal models is providing key insights into the various facets of human ASD.
Collapse
Affiliation(s)
- Swati Banerjee
- Department of Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center San Antonio, TX, USA
| | - Maeveen Riordan
- Department of Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center San Antonio, TX, USA
| | - Manzoor A Bhat
- Department of Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center San Antonio, TX, USA
| |
Collapse
|
4
|
Grabrucker AM, Schmeisser MJ, Schoen M, Boeckers TM. Postsynaptic ProSAP/Shank scaffolds in the cross-hair of synaptopathies. Trends Cell Biol 2011; 21:594-603. [PMID: 21840719 DOI: 10.1016/j.tcb.2011.07.003] [Citation(s) in RCA: 180] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 07/10/2011] [Accepted: 07/14/2011] [Indexed: 01/31/2023]
Abstract
Intact synaptic homeostasis is a fundamental prerequisite for a healthy brain. Thus, it is not surprising that altered synaptic morphology and function are involved in the molecular pathogenesis of so-called synaptopathies including autism, schizophrenia (SCZ) and Alzheimer's disease (AD). Intriguingly, various recent studies revealed a crucial role of postsynaptic ProSAP/Shank scaffold proteins in all of the aforementioned disorders. Considering these findings, we follow the hypothesis that ProSAP/Shank proteins are key regulators of synaptic development and plasticity with clear-cut isoform-specific roles. We thus propose a model where ProSAP/Shank proteins are in the center of a postsynaptic signaling pathway that is disrupted in several neuropsychiatric disorders.
Collapse
|
6
|
Suckow AT, Comoletti D, Waldrop MA, Mosedale M, Egodage S, Taylor P, Chessler SD. Expression of neurexin, neuroligin, and their cytoplasmic binding partners in the pancreatic beta-cells and the involvement of neuroligin in insulin secretion. Endocrinology 2008; 149:6006-17. [PMID: 18755801 PMCID: PMC2613060 DOI: 10.1210/en.2008-0274] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The composition of the beta-cell exocytic machinery is very similar to that of neuronal synapses, and the developmental pathway of beta-cells and neurons substantially overlap. beta-Cells secrete gamma-aminobutyric acid and express proteins that, in the brain, are specific markers of inhibitory synapses. Recently, neuronal coculture experiments have identified three families of synaptic cell-surface molecules (neurexins, neuroligins, and SynCAM) that drive synapse formation in vitro and that control the differentiation of nascent synapses into either excitatory or inhibitory fully mature nerve terminals. The inhibitory synapse-like character of the beta-cells led us to hypothesize that members of these families of synapse-inducing adhesion molecules would be expressed in beta-cells and that the pattern of expression would resemble that associated with neuronal inhibitory synaptogenesis. Here, we describe beta-cell expression of the neuroligins, neurexins, and SynCAM, and show that neuroligin expression affects insulin secretion in INS-1 beta-cells and rat islet cells. Our findings demonstrate that neuroligins and neurexins are expressed outside the central nervous system and help confer an inhibitory synaptic-like phenotype onto the beta-cell surface. Analogous to their role in synaptic neurotransmission, neurexin-neuroligin interactions may play a role in the formation of the submembrane insulin secretory apparatus.
Collapse
Affiliation(s)
- Arthur T Suckow
- Department of Medicine, Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, California 92093, USA
| | | | | | | | | | | | | |
Collapse
|