1
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Stokes EG, Kim H, Ko J, Aoto J. A Systematic Structure-Function Characterization of a Human Mutation in Neurexin-3α Reveals an Extracellular Modulatory Sequence That Stabilizes Neuroligin-1 Binding to Enhance the Postsynaptic Properties of Excitatory Synapses. J Neurosci 2024; 44:e1847232024. [PMID: 39231636 PMCID: PMC11466067 DOI: 10.1523/jneurosci.1847-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 08/20/2024] [Accepted: 08/27/2024] [Indexed: 09/06/2024] Open
Abstract
α-Neurexins are essential and highly expressed presynaptic cell-adhesion molecules that are frequently linked to neuropsychiatric and neurodevelopmental disorders. Despite their importance, how the elaborate extracellular sequences of α-neurexins contribute to synapse function is poorly understood. We recently characterized the presynaptic gain-of-function phenotype caused by a missense mutation in an evolutionarily conserved extracellular sequence of neurexin-3α (A687T) that we identified in a patient diagnosed with profound intellectual disability and epilepsy. The striking A687T gain-of-function mutation on neurexin-3α prompted us to systematically test using mutants whether the presynaptic gain-of-function phenotype is a consequence of the addition of side-chain bulk (i.e., A687V) or polar/hydrophilic properties (i.e., A687S). We used multidisciplinary approaches in mixed-sex primary hippocampal cultures to assess the impact of the neurexin-3αA687 residue on synapse morphology, function and ligand binding. Unexpectedly, neither A687V nor A687S recapitulated the neurexin-3α A687T phenotype. Instead, distinct from A687T, molecular replacement with A687S significantly enhanced postsynaptic properties exclusively at excitatory synapses and selectively increased binding to neuroligin-1 and neuroligin-3 without changing binding to neuroligin-2 or LRRTM2. Importantly, we provide the first experimental evidence supporting the notion that the position A687 of neurexin-3α and the N-terminal sequences of neuroligins may contribute to the stability of α-neurexin-neuroligin-1 trans-synaptic interactions and that these interactions may specifically regulate the postsynaptic strength of excitatory synapses.
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Affiliation(s)
- Eric G Stokes
- Department of Pharmacology, University of Colorado Anschutz School of Medicine, Colorado 80045
| | - Hyeonho Kim
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
- Center for Synapse Diversity and Specificity, DGIST, Daegu 42988, Korea
| | - Jaewon Ko
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
- Center for Synapse Diversity and Specificity, DGIST, Daegu 42988, Korea
| | - Jason Aoto
- Department of Pharmacology, University of Colorado Anschutz School of Medicine, Colorado 80045
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2
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Jukic A, Lei Z, Cebul ER, Pinter K, Tadesse Y, Jarysta A, David S, Mosqueda N, Tarchini B, Kindt K. Presynaptic Nrxn3 is essential for ribbon-synapse maturation in hair cells. Development 2024; 151:dev202723. [PMID: 39254120 DOI: 10.1242/dev.202723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 08/28/2024] [Indexed: 09/11/2024]
Abstract
Hair cells of the inner ear and lateral-line system rely on specialized ribbon synapses to transmit sensory information to the central nervous system. The molecules required to assemble these synapses are not fully understood. We show that Nrxn3, a presynaptic adhesion molecule, is crucial for ribbon-synapse maturation in hair cells. In both mouse and zebrafish models, the loss of Nrxn3 results in significantly fewer intact ribbon synapses. We show in zebrafish that, initially, Nrxn3 loss does not alter pre- and postsynapse numbers but, later, synapses fail to pair, leading to postsynapse loss. We also demonstrate that Nrxn3 subtly influences synapse selectivity in zebrafish lateral-line hair cells that detect anterior flow. Loss of Nrxn3 leads to a 60% loss of synapses in zebrafish, which dramatically reduces pre- and postsynaptic responses. Despite fewer synapses, auditory responses in zebrafish and mice are unaffected. This work demonstrates that Nrxn3 is a crucial and conserved molecule required for the maturation of ribbon synapses. Understanding how ribbon synapses mature is essential to generating new therapies to treat synaptopathies linked to auditory or vestibular dysfunction.
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Affiliation(s)
- Alma Jukic
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD 20892, USA
| | - Zhengchang Lei
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD 20892, USA
| | - Elizabeth R Cebul
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD 20892, USA
| | - Katherine Pinter
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD 20892, USA
| | - Yommi Tadesse
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD 20892, USA
| | | | - Sandeep David
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD 20892, USA
| | - Natalie Mosqueda
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD 20892, USA
| | - Basile Tarchini
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Katie Kindt
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD 20892, USA
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3
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Brockhaus J, Kahl I, Ahmad M, Repetto D, Reissner C, Missler M. Conditional Knockout of Neurexins Alters the Contribution of Calcium Channel Subtypes to Presynaptic Ca 2+ Influx. Cells 2024; 13:981. [PMID: 38891114 PMCID: PMC11171642 DOI: 10.3390/cells13110981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 05/23/2024] [Accepted: 06/03/2024] [Indexed: 06/21/2024] Open
Abstract
Presynaptic Ca2+ influx through voltage-gated Ca2+ channels (VGCCs) is a key signal for synaptic vesicle release. Synaptic neurexins can partially determine the strength of transmission by regulating VGCCs. However, it is unknown whether neurexins modulate Ca2+ influx via all VGCC subtypes similarly. Here, we performed live cell imaging of synaptic boutons from primary hippocampal neurons with a Ca2+ indicator. We used the expression of inactive and active Cre recombinase to compare control to conditional knockout neurons lacking either all or selected neurexin variants. We found that reduced total presynaptic Ca2+ transients caused by the deletion of all neurexins were primarily due to the reduced contribution of P/Q-type VGCCs. The deletion of neurexin1α alone also reduced the total presynaptic Ca2+ influx but increased Ca2+ influx via N-type VGCCs. Moreover, we tested whether the decrease in Ca2+ influx induced by activation of cannabinoid receptor 1 (CB1-receptor) is modulated by neurexins. Unlike earlier observations emphasizing a role for β-neurexins, we found that the decrease in presynaptic Ca2+ transients induced by CB1-receptor activation depended more strongly on the presence of α-neurexins in hippocampal neurons. Together, our results suggest that neurexins have unique roles in the modulation of presynaptic Ca2+ influx through VGCC subtypes and that different neurexin variants may affect specific VGCCs.
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Affiliation(s)
- Johannes Brockhaus
- Institute of Anatomy and Molecular Neurobiology, University of Münster, 48149 Münster, Germany
| | - Iris Kahl
- Institute of Anatomy and Molecular Neurobiology, University of Münster, 48149 Münster, Germany
| | - Mohiuddin Ahmad
- Institute of Anatomy and Molecular Neurobiology, University of Münster, 48149 Münster, Germany
- Department of Cell Biology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Daniele Repetto
- Institute of Anatomy and Molecular Neurobiology, University of Münster, 48149 Münster, Germany
| | - Carsten Reissner
- Institute of Anatomy and Molecular Neurobiology, University of Münster, 48149 Münster, Germany
| | - Markus Missler
- Institute of Anatomy and Molecular Neurobiology, University of Münster, 48149 Münster, Germany
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4
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Jukic A, Lei Z, Cebul ER, Pinter K, Mosqueda N, David S, Tarchini B, Kindt K. Presynaptic Nrxn3 is essential for ribbon-synapse assembly in hair cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.14.580267. [PMID: 38410471 PMCID: PMC10896334 DOI: 10.1101/2024.02.14.580267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
Hair cells of the inner ear rely on specialized ribbon synapses to transmit sensory information to the central nervous system. The molecules required to assemble these synapses are not fully understood. We show that Nrxn3, a presynaptic adhesion molecule, is critical for ribbon-synapse assembly in hair cells. In both mouse and zebrafish models, loss of Nrxn3 results in significantly fewer intact ribbon synapses. In zebrafish we demonstrate that a 60% loss of synapses in nrxn3 mutants dramatically reduces both presynaptic responses in hair cells and postsynaptic responses in afferent neurons. Despite a reduction in synapse function in this model, we find no deficits in the acoustic startle response, a behavior reliant on these synapses. Overall, this work demonstrates that Nrxn3 is a critical and conserved molecule required to assemble ribbon synapses. Understanding how ribbon synapses assemble is a key step towards generating novel therapies to treat forms of age-related and noise-induced hearing loss that occur due to loss of ribbon synapses.
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Affiliation(s)
- Alma Jukic
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD, 20892, USA
| | - Zhengchang Lei
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD, 20892, USA
| | - Elizabeth R Cebul
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD, 20892, USA
| | - Katherine Pinter
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD, 20892, USA
| | - Natalie Mosqueda
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD, 20892, USA
| | - Sandeep David
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD, 20892, USA
| | | | - Katie Kindt
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD, 20892, USA
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5
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Mohrmann L, Seebach J, Missler M, Rohlmann A. Distinct Alterations in Dendritic Spine Morphology in the Absence of β-Neurexins. Int J Mol Sci 2024; 25:1285. [PMID: 38279285 PMCID: PMC10817056 DOI: 10.3390/ijms25021285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 01/12/2024] [Accepted: 01/18/2024] [Indexed: 01/28/2024] Open
Abstract
Dendritic spines are essential for synaptic function because they constitute the postsynaptic compartment of the neurons that receives the most excitatory input. The extracellularly shorter variant of the presynaptic cell adhesion molecules neurexins, β-neurexin, has been implicated in various aspects of synaptic function, including neurotransmitter release. However, its role in developing or stabilizing dendritic spines as fundamental computational units of excitatory synapses has remained unclear. Here, we show through morphological analysis that the deletion of β-neurexins in hippocampal neurons in vitro and in hippocampal tissue in vivo affects presynaptic dense-core vesicles, as hypothesized earlier, and, unexpectedly, alters the postsynaptic spine structure. Specifically, we observed that the absence of β-neurexins led to an increase in filopodial-like protrusions in vitro and more mature mushroom-type spines in the CA1 region of adult knockout mice. In addition, the deletion of β-neurexins caused alterations in the spine head dimension and an increase in spines with perforations of their postsynaptic density but no changes in the overall number of spines or synapses. Our results indicate that presynaptic β-neurexins play a role across the synaptic cleft, possibly by aligning with postsynaptic binding partners and glutamate receptors via transsynaptic columns.
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Affiliation(s)
| | | | - Markus Missler
- Institute of Anatomy and Molecular Neurobiology, University Münster, 48149 Münster, Germany; (L.M.); (J.S.)
| | - Astrid Rohlmann
- Institute of Anatomy and Molecular Neurobiology, University Münster, 48149 Münster, Germany; (L.M.); (J.S.)
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6
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Cowen MH, Reddy KC, Chalasani SH, Hart MP. Conserved autism-associated genes tune social feeding behavior in C. elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.05.570116. [PMID: 38106124 PMCID: PMC10723370 DOI: 10.1101/2023.12.05.570116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Animal foraging is an essential and evolutionarily conserved behavior that occurs in social and solitary contexts, but the underlying molecular pathways are not well defined. We discover that conserved autism-associated genes (NRXN1(nrx-1), NLGN3(nlg-1), GRIA1,2,3(glr-1), GRIA2(glr-2), and GLRA2,GABRA3(avr-15)) regulate aggregate feeding in C. elegans, a simple social behavior. NRX-1 functions in chemosensory neurons (ADL and ASH) independently of its postsynaptic partner NLG-1 to regulate social feeding. Glutamate from these neurons is also crucial for aggregate feeding, acting independently of NRX-1 and NLG-1. Compared to solitary counterparts, social animals show faster presynaptic release and more presynaptic release sites in ASH neurons, with only the latter requiring nrx-1. Disruption of these distinct signaling components additively converts behavior from social to solitary. Aggregation induced by circuit activation is also dependent on nrx-1. Collectively, we find that aggregate feeding is tuned by conserved autism-associated genes through complementary synaptic mechanisms, revealing molecular principles driving social feeding.
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Affiliation(s)
- Mara H. Cowen
- Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, PA
- Department of Genetics, University of Pennsylvania, Philadelphia, PA
- Autism Spectrum Program of Excellence, Perelman School of Medicine, Philadelphia, PA
| | - Kirthi C. Reddy
- Molecular Neurobiology Laboratory, Salk Institute, La Jolla, CA
| | | | - Michael P. Hart
- Department of Genetics, University of Pennsylvania, Philadelphia, PA
- Autism Spectrum Program of Excellence, Perelman School of Medicine, Philadelphia, PA
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7
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Oh KH, Xiong A, Choe JY, Richmond JE, Kim H. Active Zone Trafficking of CaV2/UNC-2 Channels Is Independent of β/CCB-1 and α2δ/UNC-36 Subunits. J Neurosci 2023; 43:5142-5157. [PMID: 37160370 PMCID: PMC10343168 DOI: 10.1523/jneurosci.2264-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 03/28/2023] [Accepted: 05/02/2023] [Indexed: 05/11/2023] Open
Abstract
The CaV2 voltage-gated calcium channel is the major conduit of calcium ions necessary for neurotransmitter release at presynaptic active zones (AZs). The CaV2 channel is a multimeric complex that consists of a pore-forming α1 subunit and two auxiliary β and α2δ subunits. Although auxiliary subunits are critical for channel function, whether they are required for α1 trafficking is unresolved. Using endogenously fluorescent protein-tagged CaV2 channel subunits in Caenorhabditis elegans, we show that UNC-2/α1 localizes to AZs even in the absence of CCB-1/β or UNC-36/α2δ, albeit at low levels. When UNC-2 is manipulated to be trapped in the endoplasmic reticulum (ER), CCB-1 and UNC-36 fail to colocalize with UNC-2 in the ER, indicating that they do not coassemble with UNC-2 in the ER. Moreover, blocking ER-associated degradation does not further increase presynaptic UNC-2 channels in ccb-1 or unc-36 mutants, indicating that UNC-2 levels are not regulated in the ER. An unc-2 mutant lacking C-terminal AZ protein interaction sites with intact auxiliary subunit binding sites displays persistent presynaptic UNC-2 localization and a prominent increase of UNC-2 channels in nonsynaptic axonal regions, underscoring a protective role of auxiliary subunits against UNC-2 degradation. In the absence of UNC-2, presynaptic CCB-1 and UNC-36 are profoundly diminished to barely detectable levels, indicating that UNC-2 is required for the presynaptic localization of CCB-1 and UNC-36. Together, our findings demonstrate that although the pore-forming subunit does not require auxiliary subunits for its trafficking and transport to AZs, it recruits auxiliary subunits to stabilize and expand calcium channel signalosomes.SIGNIFICANCE STATEMENT Synaptic transmission in the neuron hinges on the coupling of synaptic vesicle exocytosis with calcium influx. This calcium influx is mediated by CaV2 voltage-gated calcium channels. These channels consist of one pore-forming α1 subunit and two auxiliary β and α2δ subunits. The auxiliary subunits enhance channel function and regulate the overall level of channels at presynaptic terminals. However, it is not settled how these auxiliary subunits regulate the overall channel level. Our study in C. elegans finds that although the auxiliary subunits do not coassemble with α1 and aid trafficking, they are recruited to α1 and stabilize the channel complex at presynaptic terminals. Our study suggests that drugs that target the auxiliary subunits can directly destabilize and have an impact on CaV2 channels.
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Affiliation(s)
- Kelly H Oh
- Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois 60064
| | - Ame Xiong
- Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois 60064
| | - Jun-Yong Choe
- Department of Chemistry, East Carolina University, Greenville, North Carolina 27858
| | - Janet E Richmond
- Department of Biological Sciences, University of Illinois, Chicago, Illinois 60607
| | - Hongkyun Kim
- Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois 60064
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8
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Reyes Fernandez PC, Wright CS, Farach-Carson MC, Thompson WR. Examining Mechanisms for Voltage-Sensitive Calcium Channel-Mediated Secretion Events in Bone Cells. Calcif Tissue Int 2023; 113:126-142. [PMID: 37261463 PMCID: PMC11008533 DOI: 10.1007/s00223-023-01097-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 05/16/2023] [Indexed: 06/02/2023]
Abstract
In addition to their well-described functions in cell excitability, voltage-sensitive calcium channels (VSCCs) serve a critical role in calcium (Ca2+)-mediated secretion of pleiotropic paracrine and endocrine factors, including those produced in bone. Influx of Ca2+ through VSCCs activates intracellular signaling pathways to modulate a variety of cellular processes that include cell proliferation, differentiation, and bone adaptation in response to mechanical stimuli. Less well understood is the role of VSCCs in the control of bone and calcium homeostasis mediated through secreted factors. In this review, we discuss the various functions of VSCCs in skeletal cells as regulators of Ca2+ dynamics and detail how these channels might control the release of bioactive factors from bone cells. Because VSCCs are druggable, a better understanding of the multiple functions of these channels in the skeleton offers the opportunity for developing new therapies to enhance and maintain bone and to improve systemic health.
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Affiliation(s)
- Perla C Reyes Fernandez
- Department of Physical Therapy, School of Health and Human Sciences, Indiana University, Indianapolis, IN, 46202, USA
- Center for Musculoskeletal Health, Indiana University, Indianapolis, IN, 46202, USA
| | - Christian S Wright
- Department of Physical Therapy, School of Health and Human Sciences, Indiana University, Indianapolis, IN, 46202, USA
- Center for Musculoskeletal Health, Indiana University, Indianapolis, IN, 46202, USA
| | - Mary C Farach-Carson
- Department of Diagnostic and Biomedical Sciences, School of Dentistry, The University of Texas Health Science Center at Houston, Houston, TX, 77054, USA
- Departments of BioSciences and Bioengineering, Rice University, Houston, TX, 77005, USA
| | - William R Thompson
- Department of Physical Therapy, School of Health and Human Sciences, Indiana University, Indianapolis, IN, 46202, USA.
- Center for Musculoskeletal Health, Indiana University, Indianapolis, IN, 46202, USA.
- Department of Anatomy, Cell Biology and Physiology, School of Medicine, Indiana University, Indianapolis, IN, 46202, USA.
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9
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Lu H, Zuo L, Roddick KM, Zhang P, Oku S, Garden J, Ge Y, Bellefontaine M, Delhaye M, Brown RE, Craig AM. Alternative splicing and heparan sulfation converge on neurexin-1 to control glutamatergic transmission and autism-related behaviors. Cell Rep 2023; 42:112714. [PMID: 37384525 DOI: 10.1016/j.celrep.2023.112714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 04/16/2023] [Accepted: 06/13/2023] [Indexed: 07/01/2023] Open
Abstract
Neurexin synaptic organizing proteins are central to a genetic risk pathway in neuropsychiatric disorders. Neurexins also exemplify molecular diversity in the brain, with over a thousand alternatively spliced forms and further structural heterogeneity contributed by heparan sulfate glycan modification. Yet, interactions between these modes of post-transcriptional and post-translational modification have not been studied. We reveal that these regulatory modes converge on neurexin-1 splice site 5 (S5): the S5 insert increases the number of heparan sulfate chains. This is associated with reduced neurexin-1 protein level and reduced glutamatergic neurotransmitter release. Exclusion of neurexin-1 S5 in mice boosts neurotransmission without altering the AMPA/NMDA ratio and shifts communication and repetitive behavior away from phenotypes associated with autism spectrum disorders. Thus, neurexin-1 S5 acts as a synaptic rheostat to impact behavior through the intersection of RNA processing and glycobiology. These findings position NRXN1 S5 as a potential therapeutic target to restore function in neuropsychiatric disorders.
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Affiliation(s)
- Hong Lu
- Djavad Mowafaghian Centre for Brain Health and Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Long Zuo
- Djavad Mowafaghian Centre for Brain Health and Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Kyle M Roddick
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Peng Zhang
- Djavad Mowafaghian Centre for Brain Health and Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Shinichiro Oku
- Djavad Mowafaghian Centre for Brain Health and Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Jessica Garden
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Yuan Ge
- Djavad Mowafaghian Centre for Brain Health and Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Michael Bellefontaine
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Mathias Delhaye
- Djavad Mowafaghian Centre for Brain Health and Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Richard E Brown
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Ann Marie Craig
- Djavad Mowafaghian Centre for Brain Health and Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 2B5, Canada.
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10
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Leyva-Leyva M, Sandoval A, Morales-Lázaro SL, Corzo-López A, Felix R, González-Ramírez R. Identification of Dp140 and α1-syntrophin as novel molecular interactors of the neuronal Ca V2.1 channel. Pflugers Arch 2023; 475:595-606. [PMID: 36964781 DOI: 10.1007/s00424-023-02803-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 02/21/2023] [Accepted: 03/06/2023] [Indexed: 03/26/2023]
Abstract
The primary function of dystrophin is to form a link between the cytoskeleton and the extracellular matrix. In addition to this crucial structural function, dystrophin also plays an essential role in clustering and organizing several signaling proteins, including ion channels. Proteomic analysis of the whole rodent brain has stressed the role of some components of the dystrophin-associated glycoprotein complex (DGC) as potential interacting proteins of the voltage-gated Ca2+ channels of the CaV2 subfamily. The interaction of CaV2 with signaling and scaffolding proteins, such as the DGC components, may influence their function, stability, and location in neurons. This work aims to study the interaction between dystrophin and CaV2.1. Our immunoprecipitation data showed the presence of a complex formed by CaV2.1, CaVα2δ-1, CaVβ4e, Dp140, and α1-syntrophin in the brain. Furthermore, proximity ligation assays (PLA) showed that CaV2.1 and CaVα2δ-1 interact with dystrophin in the hippocampus and cerebellum. Notably, Dp140 and α1-syntrophin increase CaV2.1 protein stability, half-life, permanence in the plasma membrane, and current density through recombinant CaV2.1 channels. Therefore, we have identified the Dp140 and α1-syntrophin as novel interaction partners of CaV2.1 channels in the mammalian brain. Consistent with previous findings, our work provides evidence of the role of DGC in anchoring and clustering CaV channels in a macromolecular complex.
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Affiliation(s)
- Margarita Leyva-Leyva
- Department of Molecular Biology and Histocompatibility, "Dr. Manuel Gea González" General Hospital, Mexico City, Mexico
- Posgrado en Ciencias Biológicas, Unidad de Posgrado, Universidad Nacional Autónoma de México (UNAM), Ciudad de Mexico, México
| | - Alejandro Sandoval
- School of Medicine FES Iztacala, National Autonomous University of México (UNAM), Tlalnepantla, Mexico
| | - Sara Luz Morales-Lázaro
- Departamento de Neurociencia Cognitiva, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de Mexico, México
| | - Alejandra Corzo-López
- Department of Cell Biology, Centre for Research and Advanced Studies (Cinvestav), Mexico City, Mexico
| | - Ricardo Felix
- Department of Cell Biology, Centre for Research and Advanced Studies (Cinvestav), Mexico City, Mexico.
| | - Ricardo González-Ramírez
- Department of Molecular Biology and Histocompatibility, "Dr. Manuel Gea González" General Hospital, Mexico City, Mexico.
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11
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Uchigashima M, Hayashi Y, Futai K. Regulation of Presynaptic Release Machinery by Cell Adhesion Molecules. ADVANCES IN NEUROBIOLOGY 2023; 33:333-356. [PMID: 37615873 DOI: 10.1007/978-3-031-34229-5_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
The synapse is a highly specialized asymmetric structure that transmits and stores information in the brain. The size of pre- and postsynaptic structures and function is well coordinated at the individual synapse level. For example, large postsynaptic dendritic spines have a larger postsynaptic density with higher α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) number on their surface, while juxtaposing presynaptic terminals have a larger active zone and higher release probability. This indicates that pre- and postsynaptic domains bidirectionally communicate to coordinate assembly of specific molecules on both sides of the synaptic cleft. Cell adhesion molecules (CAMs) that localize at synapses form transsynaptic protein interactions across the synaptic cleft and play important roles in synapse formation and regulation. The extracellular domain of CAMs is essential for specific synapse formation and function. In contrast, the intracellular domain is necessary for binding with synaptic molecules and signal transduction. Therefore, CAMs play an essential role on synapse function and structure. In fact, ample evidence indicates that transsynaptic CAMs instruct and modulate functions at presynaptic sites. This chapter focuses on transsynaptic protein interactions that regulate presynaptic functions emphasizing the role of neuronal CAMs and the intracellular mechanism of their regulation.
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Affiliation(s)
- Motokazu Uchigashima
- Department of Cellular Neuropathology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Yasunori Hayashi
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Kensuke Futai
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA, USA.
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12
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Hessenberger M, Haddad S, Obermair GJ. Pathophysiological Roles of Auxiliary Calcium Channel α 2δ Subunits. Handb Exp Pharmacol 2023; 279:289-316. [PMID: 36598609 DOI: 10.1007/164_2022_630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
α2δ proteins serve as auxiliary subunits of voltage-gated calcium channels, which are essential components of excitable cells such as skeletal and heart muscles, nerve cells of the brain and the peripheral nervous system, as well as endocrine cells. Over the recent years, α2δ proteins have been identified as critical regulators of synaptic functions, including the formation and differentiation of synapses. These functions require signalling mechanisms which are partly independent of calcium channels. Hence, in light of these features it is not surprising that the genes encoding for the four α2δ isoforms have recently been linked to neurological and neurodevelopmental disorders including epilepsy, autism spectrum disorders, schizophrenia, and depressive and bipolar disorders. Despite the increasing number of identified disease-associated mutations, the underlying pathophysiological mechanisms are only beginning to emerge. However, a thorough understanding of the pathophysiological role of α2δ proteins ideally serves two purposes: first, it will contribute to our understanding of general pathological mechanisms in synaptic disorders. Second, it may support the future development of novel and specific treatments for brain disorders. In this context, it is noteworthy that the antiepileptic and anti-allodynic drugs gabapentin and pregabalin both act via binding to α2δ proteins and are among the top sold drugs for treating neuropathic pain. In this book chapter, we will discuss recent developments in our understanding of the functions of α2δ proteins, both as calcium channel subunits and as independent regulatory entities. Furthermore, we present and summarize recently identified and likely pathogenic mutations in the genes encoding α2δ proteins and discuss potential underlying pathophysiological consequences at the molecular and structural level.
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Affiliation(s)
- Manuel Hessenberger
- Division Physiology, Department Pharmacology, Physiology and Microbiology, Karl Landsteiner University of Health Sciences, Krems, Austria
| | - Sabrin Haddad
- Division Physiology, Department Pharmacology, Physiology and Microbiology, Karl Landsteiner University of Health Sciences, Krems, Austria
- Institute of Physiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Gerald J Obermair
- Division Physiology, Department Pharmacology, Physiology and Microbiology, Karl Landsteiner University of Health Sciences, Krems, Austria.
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13
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Pilch KS, Ramgoolam KH, Dolphin AC. Involvement of Ca V 2.2 channels and α 2 δ-1 in homeostatic synaptic plasticity in cultured hippocampal neurons. J Physiol 2022; 600:5333-5351. [PMID: 36377048 PMCID: PMC10107484 DOI: 10.1113/jp283600] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 11/08/2022] [Indexed: 11/16/2022] Open
Abstract
In the mammalian brain, presynaptic CaV 2 channels play a pivotal role in synaptic transmission by mediating fast neurotransmitter exocytosis via influx of Ca2+ into the active zone of presynaptic terminals. However, the distribution and modulation of CaV 2.2 channels at plastic hippocampal synapses remains to be elucidated. Here, we assess CaV 2.2 channels during homeostatic synaptic plasticity, a compensatory form of homeostatic control preventing excessive or insufficient neuronal activity during which extensive active zone remodelling has been described. We show that chronic silencing of neuronal activity in mature hippocampal cultures resulted in elevated presynaptic Ca2+ transients, mediated by increased levels of CaV 2.2 channels at the presynaptic site. This work focused further on the role of α2 δ-1 subunits, important regulators of synaptic transmission and CaV 2.2 channel abundance at the presynaptic membrane. We found that α2 δ-1 overexpression reduces the contribution of CaV 2.2 channels to total Ca2+ flux without altering the amplitude of the Ca2+ transients. Levels of endogenous α2 δ-1 decreased during homeostatic synaptic plasticity, whereas the overexpression of α2 δ-1 prevented homeostatic synaptic plasticity in hippocampal neurons. Together, this study reveals a key role for CaV 2.2 channels and novel roles for α2 δ-1 during synaptic plastic adaptation. KEY POINTS: The roles of CaV 2.2 channels and α2 δ-1 in homeostatic synaptic plasticity in hippocampal neurons in culture were examined. Chronic silencing of neuronal activity resulted in elevated presynaptic Ca2+ transients, mediated by increased levels of CaV 2.2 channels at presynaptic sites. The level of endogenous α2 δ-1 decreased during homeostatic synaptic plasticity, whereas overexpression of α2 δ-1 prevented homeostatic synaptic plasticity in hippocampal neurons. Together, this study reveals a key role for CaV 2.2 channels and novel roles for α2 δ-1 during synaptic plastic adaptation.
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Affiliation(s)
- Kjara S. Pilch
- Department of NeurosciencePhysiology and PharmacologyUniversity College LondonLondonUK
| | - Krishma H. Ramgoolam
- Department of NeurosciencePhysiology and PharmacologyUniversity College LondonLondonUK
| | - Annette C. Dolphin
- Department of NeurosciencePhysiology and PharmacologyUniversity College LondonLondonUK
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14
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Reyes Fernandez PC, Wright CS, Warden SJ, Hum J, Farach-Carson MC, Thompson WR. Effects of Gabapentin and Pregabalin on Calcium Homeostasis: Implications for Physical Rehabilitation of Musculoskeletal Tissues. Curr Osteoporos Rep 2022; 20:365-378. [PMID: 36149592 PMCID: PMC10108402 DOI: 10.1007/s11914-022-00750-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/22/2022] [Indexed: 01/30/2023]
Abstract
PURPOSE OF REVIEW In this review, we discuss the mechanism of action of gabapentinoids and the potential consequences of long-term treatment with these drugs on the musculoskeletal system. RECENT FINDINGS Gabapentinoids, such as gabapentin (GBP) and pregabalin (PGB) were designed as antiepileptic reagents and are now commonly used as first-line treatment for neuropathic pain and increasingly prescribed off-label for other pain disorders such as migraines and back pain. GBP and PGB exert their analgesic actions by selectively binding the α2δ1 auxiliary subunit of voltage-sensitive calcium channels, thereby inhibiting channel function. Numerous tissues express the α2δ1 subunit where GBP and PGB can alter calcium-mediated signaling events. In tissues such as bone, muscle, and cartilage, α2δ1 has important roles in skeletal formation, mechanosensation, and normal tissue function/repair that may be affected by chronic use of gabapentinoids. Long-term use of gabapentinoids is associated with detrimental musculoskeletal outcomes, including increased fracture risk. Therefore, understanding potential complications is essential for clinicians to guide appropriate treatments.
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Affiliation(s)
- Perla C Reyes Fernandez
- Department of Physical Therapy, School of Health and Human Sciences, Indiana University, Indianapolis, IN, 46202, USA
- Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN, 46202, USA
| | - Christian S Wright
- Department of Physical Therapy, School of Health and Human Sciences, Indiana University, Indianapolis, IN, 46202, USA
- Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN, 46202, USA
| | - Stuart J Warden
- Department of Physical Therapy, School of Health and Human Sciences, Indiana University, Indianapolis, IN, 46202, USA
- Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN, 46202, USA
| | - Julia Hum
- Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN, 46202, USA
- College of Osteopathic Medicine, Marian University, Indianapolis, IN, 4622, USA
| | - Mary C Farach-Carson
- Department of Diagnostic & Biomedical Sciences, University of Texas Health Science Center at Houston School of Dentistry, Houston, TX, 77054, USA
| | - William R Thompson
- Department of Physical Therapy, School of Health and Human Sciences, Indiana University, Indianapolis, IN, 46202, USA.
- Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN, 46202, USA.
- College of Osteopathic Medicine, Marian University, Indianapolis, IN, 4622, USA.
- Department of Anatomy and Cell Biology, Indiana University, Indianapolis, IN, 46202, USA.
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15
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Janz P, Bainier M, Marashli S, Schoenenberger P, Valencia M, Redondo RL. Neurexin1α knockout rats display oscillatory abnormalities and sensory processing deficits back-translating key endophenotypes of psychiatric disorders. Transl Psychiatry 2022; 12:455. [PMID: 36307390 PMCID: PMC9616904 DOI: 10.1038/s41398-022-02224-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 10/14/2022] [Accepted: 10/18/2022] [Indexed: 11/09/2022] Open
Abstract
Neurexins are presynaptic transmembrane proteins crucial for synapse development and organization. Deletion and missense mutations in all three Neurexin genes have been identified in psychiatric disorders, with mutations in the NRXN1 gene most strongly linked to schizophrenia (SZ) and autism spectrum disorder (ASD). While the consequences of NRXN1 deletion have been extensively studied on the synaptic and behavioral levels, circuit endophenotypes that translate to the human condition have not been characterized yet. Therefore, we investigated the electrophysiology of cortico-striatal-thalamic circuits in Nrxn1α-/- rats and wildtype littermates focusing on a set of translational readouts, including spontaneous oscillatory activity, auditory-evoked oscillations and potentials, as well as mismatch negativity-like (MMN) responses and responses to social stimuli. On the behavioral level Nrxn1α-/- rats showed locomotor hyperactivity. In vivo freely moving electrophysiology revealed pronounced increases of spontaneous oscillatory power within the gamma band in all studied brain areas and elevation of gamma coherence in cortico-striatal and thalamocortical circuits of Nrxn1α-/- rats. In contrast, auditory-evoked oscillations driven by chirp-modulated tones showed reduced power in cortical areas confined to slower oscillations. Finally, Nrxn1α-/- rats exhibited altered auditory evoked-potentials and profound deficits in MMN-like responses, explained by reduced prediction error. Despite deficits for auditory stimuli, responses to social stimuli appeared intact. A central hypothesis for psychiatric and neurodevelopmental disorders is that a disbalance of excitation-to-inhibition is underlying oscillatory and sensory deficits. In a first attempt to explore the impact of inhibitory circuit modulation, we assessed the effects of enhancing tonic inhibition via δ-containing GABAA receptors (using Gaboxadol) on endophenotypes possibly associated with network hyperexcitability. Pharmacological experiments applying Gaboxadol showed genotype-specific differences, but failed to normalize oscillatory or sensory processing abnormalities. In conclusion, our study revealed endophenotypes in Nrxn1α-/- rats that could be used as translational biomarkers for drug development in psychiatric disorders.
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Affiliation(s)
- Philipp Janz
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery & Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland.
| | - Marie Bainier
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery & Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Samuel Marashli
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery & Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Philipp Schoenenberger
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery & Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Miguel Valencia
- Universidad de Navarra, CIMA, Program of Neuroscience, 31080, Pamplona, Spain
- IdiSNA, Navarra Institute for Health Research, 31080, Pamplona, Spain
- Institute of Data Science and Artificial Intelligence, Universidad de Navarra, 31080, Pamplona, Spain
| | - Roger L Redondo
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery & Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
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16
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Lichter K, Paul MM, Pauli M, Schoch S, Kollmannsberger P, Stigloher C, Heckmann M, Sirén AL. Ultrastructural analysis of wild-type and RIM1α knockout active zones in a large cortical synapse. Cell Rep 2022; 40:111382. [PMID: 36130490 DOI: 10.1016/j.celrep.2022.111382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 06/14/2022] [Accepted: 08/28/2022] [Indexed: 11/18/2022] Open
Abstract
Rab3A-interacting molecule (RIM) is crucial for fast Ca2+-triggered synaptic vesicle (SV) release in presynaptic active zones (AZs). We investigated hippocampal giant mossy fiber bouton (MFB) AZ architecture in 3D using electron tomography of rapid cryo-immobilized acute brain slices in RIM1α-/- and wild-type mice. In RIM1α-/-, AZs are larger with increased synaptic cleft widths and a 3-fold reduced number of tightly docked SVs (0-2 nm). The distance of tightly docked SVs to the AZ center is increased from 110 to 195 nm, and the width of their electron-dense material between outer SV membrane and AZ membrane is reduced. Furthermore, the SV pool in RIM1α-/- is more heterogeneous. Thus, RIM1α, besides its role in tight SV docking, is crucial for synaptic architecture and vesicle pool organization in MFBs.
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Affiliation(s)
- Katharina Lichter
- Department of Neurosurgery, University Hospital of Würzburg, 97080 Würzburg, Germany; Institute for Physiology, Department of Neurophysiology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany; Center of Mental Health, Department of Psychiatry, Psychosomatics and Psychotherapy, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Mila Marie Paul
- Institute for Physiology, Department of Neurophysiology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany; Department of Orthopedic Trauma, Hand, Plastic and Reconstructive Surgery, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Martin Pauli
- Institute for Physiology, Department of Neurophysiology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany
| | - Susanne Schoch
- Department of Neuropathology and Department of Epileptology, University Hospital Bonn, 53127 Bonn, Germany
| | - Philip Kollmannsberger
- Center for Computational and Theoretical Biology, Julius-Maximilians-University Würzburg, 97074 Würzburg, Germany
| | - Christian Stigloher
- Imaging Core Facility, Biocenter, University of Würzburg, 97074 Würzburg, Germany.
| | - Manfred Heckmann
- Institute for Physiology, Department of Neurophysiology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany.
| | - Anna-Leena Sirén
- Department of Neurosurgery, University Hospital of Würzburg, 97080 Würzburg, Germany; Institute for Physiology, Department of Neurophysiology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany.
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17
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Abstract
Voltage-gated Ca2+ (Cav) channels play pivotal roles in regulating gene transcription, neuronal excitability, and neurotransmitter release. To meet the spatial and temporal demands of visual signaling, Cav channels exhibit unusual properties in the retina compared to their counterparts in other areas of the nervous system. In this article, we review current concepts regarding the specific subtypes of Cav channels expressed in the retina, their intrinsic properties and forms of modulation, and how their dysregulation could lead to retinal disease.
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Affiliation(s)
- Brittany Williams
- Department of Cell Biology & Physiology, Carolina Institute for Developmental Disabilities, and Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina, USA
| | - J Wesley Maddox
- Department of Neuroscience, University of Texas, Austin, Texas, USA;
| | - Amy Lee
- Department of Neuroscience, University of Texas, Austin, Texas, USA;
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18
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Ablinger C, Eibl C, Geisler SM, Campiglio M, Stephens GJ, Missler M, Obermair GJ. α 2δ-4 and Cachd1 Proteins Are Regulators of Presynaptic Functions. Int J Mol Sci 2022; 23:9885. [PMID: 36077281 PMCID: PMC9456004 DOI: 10.3390/ijms23179885] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 08/15/2022] [Accepted: 08/24/2022] [Indexed: 11/17/2022] Open
Abstract
The α2δ auxiliary subunits of voltage-gated calcium channels (VGCC) were traditionally regarded as modulators of biophysical channel properties. In recent years, channel-independent functions of these subunits, such as involvement in synapse formation, have been identified. In the central nervous system, α2δ isoforms 1, 2, and 3 are strongly expressed, regulating glutamatergic synapse formation by a presynaptic mechanism. Although the α2δ-4 isoform is predominantly found in the retina with very little expression in the brain, it was recently linked to brain functions. In contrast, Cachd1, a novel α2δ-like protein, shows strong expression in brain, but its function in neurons is not yet known. Therefore, we aimed to investigate the presynaptic functions of α2δ-4 and Cachd1 by expressing individual proteins in cultured hippocampal neurons. Both α2δ-4 and Cachd1 are expressed in the presynaptic membrane and could rescue a severe synaptic defect present in triple knockout/knockdown neurons that lacked the α2δ-1-3 isoforms (α2δ TKO/KD). This observation suggests that presynaptic localization and the regulation of synapse formation in glutamatergic neurons is a general feature of α2δ proteins. In contrast to this redundant presynaptic function, α2δ-4 and Cachd1 differentially regulate the abundance of presynaptic calcium channels and the amplitude of presynaptic calcium transients. These functional differences may be caused by subtle isoform-specific differences in α1-α2δ protein-protein interactions, as revealed by structural homology modelling. Taken together, our study identifies both α2δ-4 and Cachd1 as presynaptic regulators of synapse formation, differentiation, and calcium channel functions that can at least partially compensate for the loss of α2δ-1-3. Moreover, we show that regulating glutamatergic synapse formation and differentiation is a critical and surprisingly redundant function of α2δ and Cachd1.
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Affiliation(s)
- Cornelia Ablinger
- Institute of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Clarissa Eibl
- Division Physiology, Department of Pharmacology, Physiology and Microbiology, Karl Landsteiner University of Health Sciences, 3500 Krems, Austria
| | - Stefanie M. Geisler
- Department Pharmacology and Toxicology, University of Innsbruck, 6020 Innsbruck, Austria
| | - Marta Campiglio
- Institute of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Gary J. Stephens
- Reading School of Pharmacy, University of Reading, Reading RG6 6UB, UK
| | - Markus Missler
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, 48149 Münster, Germany
| | - Gerald J. Obermair
- Institute of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria
- Division Physiology, Department of Pharmacology, Physiology and Microbiology, Karl Landsteiner University of Health Sciences, 3500 Krems, Austria
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19
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Rhoades R, Henry B, Prichett D, Fang Y, Teng S. Computational Saturation Mutagenesis to Investigate the Effects of Neurexin-1 Mutations on AlphaFold Structure. Genes (Basel) 2022; 13:789. [PMID: 35627176 PMCID: PMC9141173 DOI: 10.3390/genes13050789] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 04/20/2022] [Accepted: 04/23/2022] [Indexed: 02/05/2023] Open
Abstract
Neurexin-1 (NRXN1) is a membrane protein essential in synapse formation and cell signaling as a cell-adhesion molecule and cell-surface receptor. NRXN1 and its binding partner neuroligin have been associated with deficits in cognition. Recent genetics research has linked NRXN1 missense mutations to increased risk for brain disorders, including schizophrenia (SCZ) and autism spectrum disorder (ASD). Investigation of the structure-function relationship in NRXN1 has proven difficult due to a lack of the experimental full-length membrane protein structure. AlphaFold, a deep learning-based predictor, succeeds in high-quality protein structure prediction and offers a solution for membrane protein model construction. In the study, we applied a computational saturation mutagenesis method to analyze the systemic effects of missense mutations on protein functions in a human NRXN1 structure predicted from AlphaFold and an experimental Bos taurus structure. The folding energy changes were calculated to estimate the effects of the 29,540 mutations of AlphaFold model on protein stability. The comparative study on the experimental and computationally predicted structures shows that these energy changes are highly correlated, demonstrating the reliability of the AlphaFold structure for the downstream bioinformatics analysis. The energy calculation revealed that some target mutations associated with SCZ and ASD could make the protein unstable. The study can provide helpful information for characterizing the disease-causing mutations and elucidating the molecular mechanisms by which the variations cause SCZ and ASD. This methodology could provide the bioinformatics protocol to investigate the effects of target mutations on multiple AlphaFold structures.
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Affiliation(s)
- Raina Rhoades
- Department of Biology, Howard University, Washington, DC 20059, USA; (R.R.); (B.H.); (D.P.)
| | - Brianna Henry
- Department of Biology, Howard University, Washington, DC 20059, USA; (R.R.); (B.H.); (D.P.)
| | - Dominique Prichett
- Department of Biology, Howard University, Washington, DC 20059, USA; (R.R.); (B.H.); (D.P.)
| | - Yayin Fang
- Department of Biochemistry and Molecular Biology, Howard University, Washington, DC 20059, USA;
| | - Shaolei Teng
- Department of Biology, Howard University, Washington, DC 20059, USA; (R.R.); (B.H.); (D.P.)
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20
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Cervantes González A, Irwin DJ, Alcolea D, McMillan CT, Chen-Plotkin A, Wolk D, Sirisi S, Dols-Icardo O, Querol-Vilaseca M, Illán-Gala I, Santos-Santos MA, Fortea J, Lee EB, Trojanowski JQ, Grossman M, Lleó A, Belbin O. Multimarker synaptic protein cerebrospinal fluid panels reflect TDP-43 pathology and cognitive performance in a pathological cohort of frontotemporal lobar degeneration. Mol Neurodegener 2022; 17:29. [PMID: 35395770 PMCID: PMC8991834 DOI: 10.1186/s13024-022-00534-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 03/30/2022] [Indexed: 12/13/2022] Open
Abstract
Background Synapse degeneration is an early event in pathological frontotemporal lobar degeneration (FTLD). Consequently, a surrogate marker of synapse loss could be used to monitor early pathologic changes in patients with underlying FTLD. The aim of this study was to evaluate the relationship of antemortem cerebrospinal fluid (CSF) levels of 8 synaptic proteins with postmortem global tau and TDP-43 burden and cognitive performance and to assess their diagnostic capacity in a neuropathological FTLD cohort. Methods We included patients with a neuropathological confirmation of FTLD-Tau (n = 24, mean age-at-CSF 67 years ± 11), FTLD-TDP (n = 25, 66 years ± 9) or AD (n = 25, 73 years ± 6) as well as cognitively normal controls (n = 35, 69 years ± 7) from the Penn FTD Center and ADRC. We used a semi-quantitative measure of tau and TDP-43 inclusions to quantify pathological burden across 16 brain regions. Statistical methods included Spearman rank correlations, one-way analysis of covariance, ordinal regression, step-wise multiple linear regression and receiver-operating characteristic curves. Result CSF calsyntenin-1 and neurexin-2a were correlated in all patient groups (rs = .55 to .88). In FTLD-TDP, we observed low antemortem CSF levels of calsyntenin-1 and neurexin-2a compared to AD (.72-fold, p = .001, .77-fold, p = .04, respectively) and controls (.80-fold, p = .02, .78-fold, p = .02, respectively), which were inversely associated with post-mortem global TDP-43 burden (regression r2 = .56, p = .007 and r2 = .57, p = .006, respectively). A multimarker panel including calsyntenin-1 was associated with TDP-43 burden (r2 = .69, p = .003) and MMSE score (r2 = .19, p = .03) in FTLD. A second multimarker synaptic panel, also including calsyntenin-1, was associated with MMSE score in FTLD-tau (r2 = .49, p = .04) and improved diagnostic performance to discriminate FTLD-Tau and FTLD-TDP neuropathologic subtypes (AUC = .83). Conclusion These synaptic panels have potential in the differential diagnosis of FTLD neuropathologic subtypes and as surrogate markers of cognitive performance in future clinical trials targeting TDP-43 or tau. Supplementary Information The online version contains supplementary material available at 10.1186/s13024-022-00534-y.
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Affiliation(s)
- Alba Cervantes González
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - David J Irwin
- Penn FTD Center, Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Daniel Alcolea
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - Corey T McMillan
- Penn FTD Center, Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Alice Chen-Plotkin
- Penn Alzheimer's Disease Research Center, Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - David Wolk
- Penn Alzheimer's Disease Research Center, Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Sònia Sirisi
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - Oriol Dols-Icardo
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - Marta Querol-Vilaseca
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - Ignacio Illán-Gala
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - Miguel Angel Santos-Santos
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - Juan Fortea
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - Edward B Lee
- Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - John Q Trojanowski
- Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Murray Grossman
- Penn FTD Center, Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Alberto Lleó
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - Olivia Belbin
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain. .,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain. .,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain.
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21
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Uemura T, Suzuki-Kouyama E, Kawase S, Kurihara T, Yasumura M, Yoshida T, Fukai S, Yamazaki M, Fei P, Abe M, Watanabe M, Sakimura K, Mishina M, Tabuchi K. Neurexins play a crucial role in cerebellar granule cell survival by organizing autocrine machinery for neurotrophins. Cell Rep 2022; 39:110624. [PMID: 35385735 DOI: 10.1016/j.celrep.2022.110624] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 02/22/2022] [Accepted: 03/15/2022] [Indexed: 01/22/2023] Open
Abstract
Neurexins (NRXNs) are key presynaptic cell adhesion molecules that regulate synapse formation and function via trans-synaptic interaction with postsynaptic ligands. Here, we generate cerebellar granule cell (CGC)-specific Nrxn triple-knockout (TKO) mice for complete deletion of all NRXNs. Unexpectedly, most CGCs die in these mice, and this requirement for NRXNs for cell survival is reproduced in cultured CGCs. The axons of cultured Nrxn TKO CGCs that are not in contact with a postsynaptic structure show defects in the formation of presynaptic protein clusters and in action-potential-induced Ca2+ influxes. These cells also show impaired secretion of depolarization-induced, fluorescence-tagged brain-derived neurotrophic factor (BDNF) from their axons, and the cell-survival defect is rescued by the application of BDNF. These results suggest that CGC survival is maintained by autocrine neurotrophic factors and that NRXNs organize the presynaptic protein clusters and the autocrine neurotrophic-factor secretory machinery independent of contact with postsynaptic ligands.
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Affiliation(s)
- Takeshi Uemura
- Division of Gene Research, Research Center for Advanced Science, Shinshu University, Nagano 390-8621, Japan; Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Nagano 390-8621, Japan; Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano 390-8621, Japan; Department of Molecular Neurobiology and Pharmacology, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan; JST CREST, Saitama 332-0012, Japan.
| | - Emi Suzuki-Kouyama
- Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano 390-8621, Japan; JST CREST, Saitama 332-0012, Japan
| | - Shiori Kawase
- Division of Gene Research, Research Center for Advanced Science, Shinshu University, Nagano 390-8621, Japan; Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano 390-8621, Japan; JST CREST, Saitama 332-0012, Japan
| | - Taiga Kurihara
- Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano 390-8621, Japan
| | - Misato Yasumura
- Department of Molecular Neurobiology and Pharmacology, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan; Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Tomoyuki Yoshida
- Department of Molecular Neurobiology and Pharmacology, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan; Department of Molecular Neuroscience, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan; JST PRESTO, Saitama 332-0012, Japan
| | - Shuya Fukai
- JST CREST, Saitama 332-0012, Japan; Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Maya Yamazaki
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Peng Fei
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Manabu Abe
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata 951-8585, Japan; Department of Animal Model Development, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Masahiko Watanabe
- Department of Anatomy, Faculty of Medicine, Hokkaido University, Sapporo 060-8638, Japan
| | - Kenji Sakimura
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata 951-8585, Japan; Department of Animal Model Development, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Masayoshi Mishina
- Department of Molecular Neurobiology and Pharmacology, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan; Brain Science Laboratory, Research Organization of Science and Technology, Ritsumeikan University, Shiga 525-8577, Japan
| | - Katsuhiko Tabuchi
- Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Nagano 390-8621, Japan; Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano 390-8621, Japan; JST PRESTO, Saitama 332-0012, Japan.
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22
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Ferdos S, Brockhaus J, Missler M, Rohlmann A. Deletion of β-Neurexins in Mice Alters the Distribution of Dense-Core Vesicles in Presynapses of Hippocampal and Cerebellar Neurons. Front Neuroanat 2022; 15:757017. [PMID: 35173587 PMCID: PMC8841415 DOI: 10.3389/fnana.2021.757017] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 12/16/2021] [Indexed: 11/17/2022] Open
Abstract
Communication between neurons through synapses includes the release of neurotransmitter-containing synaptic vesicles (SVs) and of neuromodulator-containing dense-core vesicles (DCVs). Neurexins (Nrxns), a polymorphic family of cell surface molecules encoded by three genes in vertebrates (Nrxn1–3), have been proposed as essential presynaptic organizers and as candidates for cell type-specific or even synapse-specific regulation of synaptic vesicle exocytosis. However, it remains unknown whether Nrxns also regulate DCVs. Here, we report that at least β-neurexins (β-Nrxns), an extracellularly smaller Nrxn variant, are involved in the distribution of presynaptic DCVs. We found that conditional deletion of all three β-Nrxn isoforms in mice by lentivirus-mediated Cre recombinase expression in primary hippocampal neurons reduces the number of ultrastructurally identified DCVs in presynaptic boutons. Consistently, colabeling against marker proteins revealed a diminished population of chromogranin A- (ChrgA-) positive DCVs in synapses and axons of β-Nrxn-deficient neurons. Moreover, we validated the impaired DCV distribution in cerebellar brain tissue from constitutive β-Nrxn knockout (β-TKO) mice, where DCVs are normally abundant and β-Nrxn isoforms are prominently expressed. Finally, we observed that the ultrastructure and marker proteins of the Golgi apparatus, responsible for packaging neuropeptides into DCVs, seem unchanged. In conclusion, based on the validation from the two deletion strategies in conditional and constitutive KO mice, two neuronal populations from the hippocampus and cerebellum, and two experimental protocols in cultured neurons and in the brain tissue, this study presented morphological evidence that the number of DCVs at synapses is altered in the absence of β-Nrxns. Our results therefore point to an unexpected contribution of β-Nrxns to the organization of neuropeptide and neuromodulator function, in addition to their more established role in synaptic vesicle release.
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23
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Heck J, Palmeira Do Amaral AC, Weißbach S, El Khallouqi A, Bikbaev A, Heine M. More than a pore: How voltage-gated calcium channels act on different levels of neuronal communication regulation. Channels (Austin) 2021; 15:322-338. [PMID: 34107849 PMCID: PMC8205089 DOI: 10.1080/19336950.2021.1900024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/04/2021] [Accepted: 03/04/2021] [Indexed: 02/06/2023] Open
Abstract
Voltage-gated calcium channels (VGCCs) represent key regulators of the calcium influx through the plasma membrane of excitable cells, like neurons. Activated by the depolarization of the membrane, the opening of VGCCs induces very transient and local changes in the intracellular calcium concentration, known as calcium nanodomains, that in turn trigger calcium-dependent signaling cascades and the release of chemical neurotransmitters. Based on their central importance as concierges of excitation-secretion coupling and therefore neuronal communication, VGCCs have been studied in multiple aspects of neuronal function and malfunction. However, studies on molecular interaction partners and recent progress in omics technologies have extended the actual concept of these molecules. With this review, we want to illustrate some new perspectives of VGCCs reaching beyond their function as calcium-permeable pores in the plasma membrane. Therefore, we will discuss the relevance of VGCCs as voltage sensors in functional complexes with ryanodine receptors, channel-independent actions of auxiliary VGCC subunits, and provide an insight into how VGCCs even directly participate in gene regulation. Furthermore, we will illustrate how structural changes in the intracellular C-terminus of VGCCs generated by alternative splicing events might not only affect the biophysical channel characteristics but rather determine their molecular environment and downstream signaling pathways.
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Affiliation(s)
- Jennifer Heck
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
| | - Ana Carolina Palmeira Do Amaral
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
| | - Stephan Weißbach
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
- Computational Genomics and Bioinformatics, Johannes Gutenberg-University Mainz, University Medical Center Mainz, Institute for Human Genetics, Mainz, Germany
| | - Abderazzaq El Khallouqi
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
| | - Arthur Bikbaev
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
| | - Martin Heine
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
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24
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Dagar S, Teng Z, Gottmann K. Transsynaptic N-Cadherin Adhesion Complexes Control Presynaptic Vesicle and Bulk Endocytosis at Physiological Temperature. Front Cell Neurosci 2021; 15:713693. [PMID: 34759800 PMCID: PMC8573734 DOI: 10.3389/fncel.2021.713693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Accepted: 09/13/2021] [Indexed: 11/30/2022] Open
Abstract
At mammalian glutamatergic synapses, most basic elements of synaptic transmission have been shown to be modulated by specific transsynaptic adhesion complexes. However, although crucial for synapse homeostasis, a physiological regulation of synaptic vesicle endocytosis by adhesion molecules has not been firmly established. The homophilic adhesion protein N-cadherin is localized at the peri-active zone, where the highly temperature-dependent endocytosis of vesicles occurs. Here, we demonstrate an important modulatory role of N-cadherin in endocytosis at near physiological temperature by synaptophysin-pHluorin imaging. Different modes of endocytosis including bulk endocytosis were dependent on N-cadherin expression and function. N-cadherin modulation might be mediated by actin filaments because actin polymerization ameliorated the knockout-induced endocytosis defect. Using super-resolution imaging, we found strong recruitment of N-cadherin to glutamatergic synapses upon massive vesicle release, which might in turn enhance vesicle endocytosis. This provides a novel, adhesion protein-mediated mechanism for efficient coupling of exo- and endocytosis.
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Affiliation(s)
- Sushma Dagar
- Institute of Neuro- and Sensory Physiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Zenghui Teng
- Institute of Neuro- and Sensory Physiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Kurt Gottmann
- Institute of Neuro- and Sensory Physiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
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25
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Luo JK, Melland H, Nithianantharajah J, Gordon SL. Postsynaptic Neuroligin-1 Mediates Presynaptic Endocytosis During Neuronal Activity. Front Mol Neurosci 2021; 14:744845. [PMID: 34690694 PMCID: PMC8531268 DOI: 10.3389/fnmol.2021.744845] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 09/15/2021] [Indexed: 01/31/2023] Open
Abstract
Fast, high-fidelity neurotransmission and synaptic efficacy requires tightly regulated coordination of pre- and postsynaptic compartments and alignment of presynaptic release sites with postsynaptic receptor nanodomains. Neuroligin-1 (Nlgn1) is a postsynaptic cell-adhesion protein exclusively localised to excitatory synapses that is crucial for coordinating the transsynaptic alignment of presynaptic release sites with postsynaptic AMPA receptors as well as postsynaptic transmission and plasticity. However, little is understood about whether the postsynaptic machinery can mediate the molecular architecture and activity of the presynaptic nerve terminal, and thus it remains unclear whether there are presynaptic contributions to Nlgn1-dependent control of signalling and plasticity. Here, we employed a presynaptic reporter of neurotransmitter release and synaptic vesicle dynamics, synaptophysin-pHluorin (sypHy), to directly assess the presynaptic impact of loss of Nlgn1. We show that lack of Nlgn1 had no effect on the size of the readily releasable or entire recycling pool of synaptic vesicles, nor did it impact exocytosis. However, we observed significant changes in the retrieval of synaptic vesicles by compensatory endocytosis, specifically during activity. Our data extends growing evidence that synaptic adhesion molecules critical for forming transsynaptic scaffolds are also important for regulating activity-induced endocytosis at the presynapse.
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Affiliation(s)
- Jiaqi Keith Luo
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Holly Melland
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia.,Melbourne Dementia Research Centre, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Jess Nithianantharajah
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Sarah L Gordon
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia.,Melbourne Dementia Research Centre, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
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26
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Klatt O, Repetto D, Brockhaus J, Reissner C, El Khallouqi A, Rohlmann A, Heine M, Missler M. Endogenous β-neurexins on axons and within synapses show regulated dynamic behavior. Cell Rep 2021; 35:109266. [PMID: 34133920 DOI: 10.1016/j.celrep.2021.109266] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 12/21/2020] [Accepted: 05/26/2021] [Indexed: 11/25/2022] Open
Abstract
Neurexins are key organizer molecules that regulate synaptic function and are implicated in autism and schizophrenia. β-neurexins interact with numerous cell adhesion and receptor molecules, but their neuronal localization remains elusive. Using single-molecule tracking and high-resolution microscopy to detect neurexin1β and neurexin3β in primary hippocampal neurons from knockin mice, we demonstrate that endogenous β-neurexins are present in fewer than half of excitatory and inhibitory synapses. Moreover, we observe a large extrasynaptic pool of β-neurexins on axons and show that axonal β-neurexins diffuse with higher surface mobility than those transiently confined within synapses. Stimulation of neuronal activity further increases the mobility of synaptic and axonal β-neurexins, whereas inhibition causes the opposite. Blocking ectodomain cleavage by metalloproteases also reduces β-neurexin mobility and enhances glutamate release. These findings suggest that the surface mobility of endogenous β-neurexins inside and outside of synapses is dynamically regulated and linked to neuronal activity.
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Affiliation(s)
- Oliver Klatt
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, 48149 Münster, Germany; Functional Neurobiology Group, Institute for Developmental Biology and Neurobiology, Johannes Gutenberg University, 55128 Mainz, Germany
| | - Daniele Repetto
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, 48149 Münster, Germany
| | - Johannes Brockhaus
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, 48149 Münster, Germany
| | - Carsten Reissner
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, 48149 Münster, Germany
| | - Abderazzaq El Khallouqi
- Functional Neurobiology Group, Institute for Developmental Biology and Neurobiology, Johannes Gutenberg University, 55128 Mainz, Germany
| | - Astrid Rohlmann
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, 48149 Münster, Germany
| | - Martin Heine
- Functional Neurobiology Group, Institute for Developmental Biology and Neurobiology, Johannes Gutenberg University, 55128 Mainz, Germany.
| | - Markus Missler
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, 48149 Münster, Germany.
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27
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Meyer JO, Dolphin AC. Rab11-dependent recycling of calcium channels is mediated by auxiliary subunit α 2δ-1 but not α 2δ-3. Sci Rep 2021; 11:10256. [PMID: 33986433 PMCID: PMC8119971 DOI: 10.1038/s41598-021-89820-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/16/2021] [Indexed: 11/18/2022] Open
Abstract
N-type voltage-gated calcium channels (CaV2.2) are predominantly expressed at presynaptic terminals, and their function is regulated by auxiliary α2δ and β subunits. All four mammalian α2δ subunits enhance calcium currents through CaV1 and CaV2 channels, and this increase is attributed, in part, to increased CaV expression at the plasma membrane. In the present study we provide evidence that α2δ-1, like α2δ-2, is recycled to the plasma membrane through a Rab11a-dependent endosomal recycling pathway. Using a dominant-negative Rab11a mutant, Rab11a(S25N), we show that α2δ-1 increases plasma membrane CaV2.2 expression by increasing the rate and extent of net forward CaV2.2 trafficking in a Rab11a-dependent manner. Dominant-negative Rab11a also reduces the ability of α2δ-1 to increase CaV2.2 expression on the cell-surface of hippocampal neurites. In contrast, α2δ-3 does not enhance rapid forward CaV2.2 trafficking, regardless of whether Rab11a(S25N) is present. In addition, whole-cell CaV2.2 currents are reduced by co-expression of Rab11a(S25N) in the presence of α2δ-1, but not α2δ-3. Taken together these data suggest that α2δ subtypes participate in distinct trafficking pathways which in turn influence the localisation and function of CaV2.2.
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Affiliation(s)
- James O Meyer
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
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28
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Schöpf CL, Ablinger C, Geisler SM, Stanika RI, Campiglio M, Kaufmann WA, Nimmervoll B, Schlick B, Brockhaus J, Missler M, Shigemoto R, Obermair GJ. Presynaptic α 2δ subunits are key organizers of glutamatergic synapses. Proc Natl Acad Sci U S A 2021; 118:e1920827118. [PMID: 33782113 PMCID: PMC8040823 DOI: 10.1073/pnas.1920827118] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
In nerve cells the genes encoding for α2δ subunits of voltage-gated calcium channels have been linked to synaptic functions and neurological disease. Here we show that α2δ subunits are essential for the formation and organization of glutamatergic synapses. Using a cellular α2δ subunit triple-knockout/knockdown model, we demonstrate a failure in presynaptic differentiation evidenced by defective presynaptic calcium channel clustering and calcium influx, smaller presynaptic active zones, and a strongly reduced accumulation of presynaptic vesicle-associated proteins (synapsin and vGLUT). The presynaptic defect is associated with the downscaling of postsynaptic AMPA receptors and the postsynaptic density. The role of α2δ isoforms as synaptic organizers is highly redundant, as each individual α2δ isoform can rescue presynaptic calcium channel trafficking and expression of synaptic proteins. Moreover, α2δ-2 and α2δ-3 with mutated metal ion-dependent adhesion sites can fully rescue presynaptic synapsin expression but only partially calcium channel trafficking, suggesting that the regulatory role of α2δ subunits is independent from its role as a calcium channel subunit. Our findings influence the current view on excitatory synapse formation. First, our study suggests that postsynaptic differentiation is secondary to presynaptic differentiation. Second, the dependence of presynaptic differentiation on α2δ implicates α2δ subunits as potential nucleation points for the organization of synapses. Finally, our results suggest that α2δ subunits act as transsynaptic organizers of glutamatergic synapses, thereby aligning the synaptic active zone with the postsynaptic density.
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Affiliation(s)
- Clemens L Schöpf
- Institute of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Cornelia Ablinger
- Institute of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Stefanie M Geisler
- Institute of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
- Department of Pharmacology and Toxicology, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Ruslan I Stanika
- Division of Physiology, Karl Landsteiner University of Health Sciences, A-3500 Krems, Austria
| | - Marta Campiglio
- Institute of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Walter A Kaufmann
- Institute of Science and Technology Austria, A-3400 Klosterneuburg, Austria
| | - Benedikt Nimmervoll
- Institute of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Bettina Schlick
- Institute of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Johannes Brockhaus
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms University, 48149 Münster, Germany
| | - Markus Missler
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms University, 48149 Münster, Germany
| | - Ryuichi Shigemoto
- Institute of Science and Technology Austria, A-3400 Klosterneuburg, Austria
| | - Gerald J Obermair
- Institute of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria;
- Division of Physiology, Karl Landsteiner University of Health Sciences, A-3500 Krems, Austria
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29
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Khalaj AJ, Sterky FH, Sclip A, Schwenk J, Brunger AT, Fakler B, Südhof TC. Deorphanizing FAM19A proteins as pan-neurexin ligands with an unusual biosynthetic binding mechanism. J Cell Biol 2021; 219:151974. [PMID: 32706374 PMCID: PMC7480106 DOI: 10.1083/jcb.202004164] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 06/01/2020] [Accepted: 06/05/2020] [Indexed: 12/14/2022] Open
Abstract
Neurexins are presynaptic adhesion molecules that organize synapses by binding to diverse trans-synaptic ligands, but how neurexins are regulated is incompletely understood. Here we identify FAM19A/TAFA proteins, “orphan" cytokines, as neurexin regulators that interact with all neurexins, except for neurexin-1γ, via an unusual mechanism. Specifically, we show that FAM19A1-A4 bind to the cysteine-loop domain of neurexins by forming intermolecular disulfide bonds during transport through the secretory pathway. FAM19A-binding required both the cysteines of the cysteine-loop domain and an adjacent sequence of neurexins. Genetic deletion of neurexins suppressed FAM19A1 expression, demonstrating that FAM19As physiologically interact with neurexins. In hippocampal cultures, expression of exogenous FAM19A1 decreased neurexin O-glycosylation and suppressed its heparan sulfate modification, suggesting that FAM19As regulate the post-translational modification of neurexins. Given the selective expression of FAM19As in specific subtypes of neurons and their activity-dependent regulation, these results suggest that FAM19As serve as cell type–specific regulators of neurexin modifications.
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Affiliation(s)
- Anna J Khalaj
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA
| | - Fredrik H Sterky
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA
| | - Alessandra Sclip
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA
| | - Jochen Schwenk
- Institute of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Axel T Brunger
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA
| | - Bernd Fakler
- Institute of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Centres for Biological Signalling Studies (BIOSS) and Integrative Biological Signalling Studies (CIBSS), Freiburg, Germany.,Center for Basics in NeuroModulation, Freiburg, Germany
| | - Thomas C Südhof
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA
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30
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Abstract
The function of neuronal circuits relies on the properties of individual neuronal cells and their synapses. We propose that a substantial degree of synapse formation and function is instructed by molecular codes resulting from transcriptional programmes. Recent studies on the Neurexin protein family and its ligands provide fundamental insight into how synapses are assembled and remodelled, how synaptic properties are specified and how single gene mutations associated with neurodevelopmental and psychiatric disorders might modify the operation of neuronal circuits and behaviour. In this Review, we first summarize insights into Neurexin function obtained from various model organisms. We then discuss the mechanisms and logic of the cell type-specific regulation of Neurexin isoforms, in particular at the level of alternative mRNA splicing. Finally, we propose a conceptual framework for how combinations of synaptic protein isoforms act as 'senders' and 'readers' to instruct synapse formation and the acquisition of cell type-specific and synapse-specific functional properties.
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31
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Gandini MA, Zamponi GW. Voltage‐gated calcium channel nanodomains: molecular composition and function. FEBS J 2021; 289:614-633. [DOI: 10.1111/febs.15759] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/05/2021] [Accepted: 02/10/2021] [Indexed: 12/16/2022]
Affiliation(s)
- Maria A. Gandini
- Department of Physiology and Pharmacology Alberta Children’s Hospital Research Institute Hotchkiss Brain Institute Cumming School of Medicine University of Calgary AB Canada
| | - Gerald W. Zamponi
- Department of Physiology and Pharmacology Alberta Children’s Hospital Research Institute Hotchkiss Brain Institute Cumming School of Medicine University of Calgary AB Canada
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32
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Geisler SM, Benedetti A, Schöpf CL, Schwarzer C, Stefanova N, Schwartz A, Obermair GJ. Phenotypic Characterization and Brain Structure Analysis of Calcium Channel Subunit α 2δ-2 Mutant (Ducky) and α 2δ Double Knockout Mice. Front Synaptic Neurosci 2021; 13:634412. [PMID: 33679366 PMCID: PMC7933509 DOI: 10.3389/fnsyn.2021.634412] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 01/11/2021] [Indexed: 01/19/2023] Open
Abstract
Auxiliary α2δ subunits of voltage-gated calcium channels modulate channel trafficking, current properties, and synapse formation. Three of the four isoforms (α2δ-1, α2δ-2, and α2δ-3) are abundantly expressed in the brain; however, of the available knockout models, only α2δ-2 knockout or mutant mice display an obvious abnormal neurological phenotype. Thus, we hypothesize that the neuronal α2δ isoforms may have partially specific as well as redundant functions. To address this, we generated three distinct α2δ double knockout mouse models by crossbreeding single knockout (α2δ-1 and -3) or mutant (α2δ-2/ducky) mice. Here, we provide a first phenotypic description and brain structure analysis. We found that genotypic distribution of neonatal litters in distinct α2δ-1/-2, α2δ-1/-3, and α2δ-2/-3 breeding combinations did not conform to Mendel's law, suggesting premature lethality of single and double knockout mice. Notably, high occurrences of infant mortality correlated with the absence of specific α2δ isoforms (α2Δ-2 > α2δ-1 > α2δ-3), and was particularly observed in cages with behaviorally abnormal parenting animals of α2δ-2/-3 cross-breedings. Juvenile α2δ-1/-2 and α2δ-2/-3 double knockout mice displayed a waddling gate similar to ducky mice. However, in contrast to ducky and α2δ-1/-3 double knockout animals, α2δ-1/-2 and α2δ-2/-3 double knockout mice showed a more severe disease progression and highly impaired development. The observed phenotypes within the individual mouse lines may be linked to differences in the volume of specific brain regions. Reduced cortical volume in ducky mice, for example, was associated with a progressively decreased space between neurons, suggesting a reduction of total synaptic connections. Taken together, our findings show that α2δ subunits differentially regulate premature survival, postnatal growth, brain development, and behavior, suggesting specific neuronal functions in health and disease.
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Affiliation(s)
- Stefanie M. Geisler
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Ariane Benedetti
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Clemens L. Schöpf
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Christoph Schwarzer
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
| | - Nadia Stefanova
- Division of Neurobiology, Department of Neurology, Medical University Innsbruck, Innsbruck, Austria
| | - Arnold Schwartz
- Department of Pharmacology and Systems Physiology, College of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - Gerald J. Obermair
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
- Division Physiology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
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Serwach K, Gruszczynska-Biegala J. Target Molecules of STIM Proteins in the Central Nervous System. Front Mol Neurosci 2020; 13:617422. [PMID: 33424550 PMCID: PMC7786003 DOI: 10.3389/fnmol.2020.617422] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 12/02/2020] [Indexed: 12/16/2022] Open
Abstract
Stromal interaction molecules (STIMs), including STIM1 and STIM2, are single-pass transmembrane proteins that are located predominantly in the endoplasmic reticulum (ER). They serve as calcium ion (Ca2+) sensors within the ER. In the central nervous system (CNS), they are involved mainly in Orai-mediated store-operated Ca2+ entry (SOCE). The key molecular components of the SOCE pathway are well-characterized, but the molecular mechanisms that underlie the regulation of this pathway need further investigation. Numerous intracellular target proteins that are located in the plasma membrane, ER, cytoskeleton, and cytoplasm have been reported to play essential roles in concert with STIMs, such as conformational changes in STIMs, their translocation, the stabilization of their interactions with Orai, and the activation of other channels. The present review focuses on numerous regulators, such as Homer, SOCE-associated regulatory factor (SARAF), septin, synaptopodin, golli proteins, partner of STIM1 (POST), and transcription factors and proteasome inhibitors that regulate STIM-Orai interactions in the CNS. Further we describe novel roles of STIMs in mediating Ca2+ influx via other than Orai pathways, including TRPC channels, VGCCs, AMPA and NMDA receptors, and group I metabotropic glutamate receptors. This review also summarizes recent findings on additional molecular targets of STIM proteins including SERCA, IP3Rs, end-binding proteins (EB), presenilin, and CaMKII. Dysregulation of the SOCE-associated toolkit, including STIMs, contributes to the development of neurodegenerative disorders (e.g., Alzheimer's disease, Parkinson's disease, and Huntington's disease), traumatic brain injury, epilepsy, and stroke. Emerging evidence points to the role of STIM proteins and several of their molecular effectors and regulators in neuronal and glial physiology and pathology, suggesting their potential application for future therapeutic strategies.
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Affiliation(s)
- Karolina Serwach
- Molecular Biology Unit, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
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Different functions of two putative Drosophila α 2δ subunits in the same identified motoneurons. Sci Rep 2020; 10:13670. [PMID: 32792569 PMCID: PMC7426832 DOI: 10.1038/s41598-020-69748-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 07/15/2020] [Indexed: 11/24/2022] Open
Abstract
Voltage gated calcium channels (VGCCs) regulate neuronal excitability and translate activity into calcium dependent signaling. The α1 subunit of high voltage activated (HVA) VGCCs associates with α2δ accessory subunits, which may affect calcium channel biophysical properties, cell surface expression, localization and transport and are thus important players in calcium-dependent signaling. In vertebrates, the functions of the different combinations of the four α2δ and the seven HVA α1 subunits are incompletely understood, in particular with respect to partially redundant or separate functions in neurons. This study capitalizes on the relatively simpler situation in the Drosophila genetic model containing two neuronal putative α2δ subunits, straightjacket and CG4587, and one Cav1 and Cav2 homolog each, both with well-described functions in different compartments of identified motoneurons. Straightjacket is required for normal Cav1 and Cav2 current amplitudes and correct Cav2 channel function in all neuronal compartments. By contrast, CG4587 does not affect Cav1 or Cav2 current amplitudes or presynaptic function, but is required for correct Cav2 channel allocation to the axonal versus the dendritic domain. We suggest that the two different putative α2δ subunits are required in the same neurons to regulate different functions of VGCCs.
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Ablinger C, Geisler SM, Stanika RI, Klein CT, Obermair GJ. Neuronal α 2δ proteins and brain disorders. Pflugers Arch 2020; 472:845-863. [PMID: 32607809 PMCID: PMC7351808 DOI: 10.1007/s00424-020-02420-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/08/2020] [Accepted: 06/12/2020] [Indexed: 01/31/2023]
Abstract
α2δ proteins are membrane-anchored extracellular glycoproteins which are abundantly expressed in the brain and the peripheral nervous system. They serve as regulatory subunits of voltage-gated calcium channels and, particularly in nerve cells, regulate presynaptic and postsynaptic functions independently from their role as channel subunits. α2δ proteins are the targets of the widely prescribed anti-epileptic and anti-allodynic drugs gabapentin and pregabalin, particularly for the treatment of neuropathic pain conditions. Recently, the human genes (CACNA2D1-4) encoding for the four known α2δ proteins (isoforms α2δ-1 to α2δ-4) have been linked to a large variety of neurological and neuropsychiatric disorders including epilepsy, autism spectrum disorders, bipolar disorders, schizophrenia, and depressive disorders. Here, we provide an overview of the hitherto identified disease associations of all known α2δ genes, hypothesize on the pathophysiological mechanisms considering their known physiological roles, and discuss the most immanent future research questions. Elucidating their specific physiological and pathophysiological mechanisms may open the way for developing entirely novel therapeutic paradigms for treating brain disorders.
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Affiliation(s)
- Cornelia Ablinger
- Institute of Physiology, Medical University Innsbruck, 6020, Innsbruck, Austria
| | - Stefanie M Geisler
- Department of Pharmacology and Toxicology, University of Innsbruck, 6020, Innsbruck, Austria
| | - Ruslan I Stanika
- Division Physiology, Karl Landsteiner University of Health Sciences, 3500, Krems, Austria
| | - Christian T Klein
- Department of Life Sciences, IMC University of Applied Sciences, 3500, Krems, Austria
| | - Gerald J Obermair
- Institute of Physiology, Medical University Innsbruck, 6020, Innsbruck, Austria.
- Division Physiology, Karl Landsteiner University of Health Sciences, 3500, Krems, Austria.
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Bikbaev A, Ciuraszkiewicz-Wojciech A, Heck J, Klatt O, Freund R, Mitlöhner J, Enrile Lacalle S, Sun M, Repetto D, Frischknecht R, Ablinger C, Rohlmann A, Missler M, Obermair GJ, Di Biase V, Heine M. Auxiliary α2δ1 and α2δ3 Subunits of Calcium Channels Drive Excitatory and Inhibitory Neuronal Network Development. J Neurosci 2020; 40:4824-4841. [PMID: 32414783 PMCID: PMC7326358 DOI: 10.1523/jneurosci.1707-19.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 03/31/2020] [Accepted: 05/09/2020] [Indexed: 01/21/2023] Open
Abstract
VGCCs are multisubunit complexes that play a crucial role in neuronal signaling. Auxiliary α2δ subunits of VGCCs modulate trafficking and biophysical properties of the pore-forming α1 subunit and trigger excitatory synaptogenesis. Alterations in the expression level of α2δ subunits were implicated in several syndromes and diseases, including chronic neuropathic pain, autism, and epilepsy. However, the contribution of distinct α2δ subunits to excitatory/inhibitory imbalance and aberrant network connectivity characteristic for these pathologic conditions remains unclear. Here, we show that α2δ1 overexpression enhances spontaneous neuronal network activity in developing and mature cultures of hippocampal neurons. In contrast, overexpression, but not downregulation, of α2δ3 enhances neuronal firing in immature cultures, whereas later in development it suppresses neuronal activity. We found that α2δ1 overexpression increases excitatory synaptic density and selectively enhances presynaptic glutamate release, which is impaired on α2δ1 knockdown. Overexpression of α2δ3 increases the excitatory synaptic density as well but also facilitates spontaneous GABA release and triggers an increase in the density of inhibitory synapses, which is accompanied by enhanced axonaloutgrowth in immature interneurons. Together, our findings demonstrate that α2δ1 and α2δ3 subunits play distinct but complementary roles in driving formation of structural and functional network connectivity during early development. An alteration in α2δ surface expression during critical developmental windows can therefore play a causal role and have a profound impact on the excitatory-to-inhibitory balance and network connectivity.SIGNIFICANCE STATEMENT The computational capacity of neuronal networks is determined by their connectivity. Chemical synapses are the main interface for transfer of information between individual neurons. The initial formation of network connectivity requires spontaneous electrical activity and the calcium channel-mediated signaling. We found that, in early development, auxiliary α2δ3 subunits of calcium channels foster presynaptic release of GABA, trigger formation of inhibitory synapses, and promote axonal outgrowth in inhibitory interneurons. In contrast, later in development, α2δ1 subunits promote the glutamatergic neurotransmission and synaptogenesis, as well as strongly enhance neuronal network activity. We propose that formation of connectivity in neuronal networks is associated with a concerted interplay of α2δ1 and α2δ3 subunits of calcium channels.
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Affiliation(s)
- Arthur Bikbaev
- RG Functional Neurobiology, Institute for Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, 55128, Germany
| | - Anna Ciuraszkiewicz-Wojciech
- RG Molecular Physiology, Leibniz Institute for Neurobiology, Magdeburg, 39118, Germany
- Center for Behavioral Brain Sciences, Otto-von-Guericke University Magdeburg, Magdeburg, 39106, Germany
| | - Jennifer Heck
- RG Functional Neurobiology, Institute for Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, 55128, Germany
| | - Oliver Klatt
- Institute for Anatomy and Molecular Neurobiology, University of Münster, Münster, 48149, Germany
| | - Romy Freund
- RG Molecular Physiology, Leibniz Institute for Neurobiology, Magdeburg, 39118, Germany
| | - Jessica Mitlöhner
- RG Brain Extracellular Matrix, Leibniz Institute for Neurobiology, Magdeburg, 39118, Germany
| | - Sara Enrile Lacalle
- RG Molecular Physiology, Leibniz Institute for Neurobiology, Magdeburg, 39118, Germany
| | - Miao Sun
- Institute for Anatomy and Molecular Neurobiology, University of Münster, Münster, 48149, Germany
| | - Daniele Repetto
- Institute for Anatomy and Molecular Neurobiology, University of Münster, Münster, 48149, Germany
| | - Renato Frischknecht
- RG Brain Extracellular Matrix, Leibniz Institute for Neurobiology, Magdeburg, 39118, Germany
- Department of Biology, Animal Physiology, Friedrich Alexander University of Erlangen-Nuremberg, Erlangen, 91058, Germany
| | - Cornelia Ablinger
- Institute of Physiology, Medical University Innsbruck, Innsbruck, 6020, Austria
| | - Astrid Rohlmann
- Institute for Anatomy and Molecular Neurobiology, University of Münster, Münster, 48149, Germany
| | - Markus Missler
- Institute for Anatomy and Molecular Neurobiology, University of Münster, Münster, 48149, Germany
| | - Gerald J Obermair
- Division Physiology, Karl Landsteiner University of Health Sciences, Krems, 3500, Austria
| | - Valentina Di Biase
- Institute of Molecular and Clinical Pharmacology, Medical University Innsbruck, Innsbruck, 6020, Austria
| | - Martin Heine
- RG Functional Neurobiology, Institute for Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, 55128, Germany
- Center for Behavioral Brain Sciences, Otto-von-Guericke University Magdeburg, Magdeburg, 39106, Germany
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Risher WC, Eroglu C. Emerging roles for α2δ subunits in calcium channel function and synaptic connectivity. Curr Opin Neurobiol 2020; 63:162-169. [PMID: 32521436 DOI: 10.1016/j.conb.2020.04.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 04/29/2020] [Indexed: 12/17/2022]
Abstract
Central nervous system function requires the proper formation and function of synapses. The α2δ auxiliary subunits of voltage-gated calcium channels have emerged as regulators of a number of critical events associated with regulation of synaptic function, including channel trafficking and localization, as well as the initial establishment of synaptic structures. In this review, we will discuss some of these recent studies which have uncovered novel mechanisms for α2δ function at the synapse, including the regulation of calcium channel α1 subunit specificity and the promotion of dendritic spine growth. Moreover, we will cover recent advances that have been made in understanding the consequences of aberrant α2δ signaling in injury and disease.
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Affiliation(s)
- William Christopher Risher
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine at Marshall University, Huntington, WV 25705, United States.
| | - Cagla Eroglu
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, United States; Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, United States; Duke Institute for Brain Sciences (DIBS), Durham, NC 27710, United States; Regeneration Next Initiative, Duke University, Durham, NC 27710, United States
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38
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Taylor CP, Harris EW. Analgesia with Gabapentin and Pregabalin May Involve N-Methyl-d-Aspartate Receptors, Neurexins, and Thrombospondins. J Pharmacol Exp Ther 2020; 374:161-174. [DOI: 10.1124/jpet.120.266056] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 04/17/2020] [Indexed: 11/22/2022] Open
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Alles SRA, Cain SM, Snutch TP. Pregabalin as a Pain Therapeutic: Beyond Calcium Channels. Front Cell Neurosci 2020; 14:83. [PMID: 32351366 PMCID: PMC7174704 DOI: 10.3389/fncel.2020.00083] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 03/20/2020] [Indexed: 12/12/2022] Open
Abstract
Initially developed to generate new treatments for epilepsy, gabapentin, and pregabalin (“gabapentinoids”) were engineered to mimic the action of GABA and to modulate GABA metabolism. Rather than their intended pharmacological action on GABA neurotransmission, instead, they exhibit a high affinity for the α2δ-1 and α2δ-2 subunits of voltage-activated calcium channels, wherein binding of gabapentinoids inhibits cellular calcium influx and attenuates neurotransmission. Despite a lack of activity on GABA levels, gabapentin and pregabalin are effective at suppressing seizures and subsequently approved as a new class of antiepileptic therapy for partial-onset epilepsy. Through the same hypothesized molecular mechanism and by controlling neuronal hyperexcitability, gabapentinoids demonstrate clear efficacy in pain management, which has arguably been their most extensively prescribed application to date. In this review, we focus on pregabalin as a second-generation gabapentinoid widely employed in the treatment of a variety of pain conditions. We also discuss the wider functional roles of α2δ subunits and the contributions that pregabalin might play in affecting physiological and pathophysiological processes.
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Affiliation(s)
- Sascha R A Alles
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada.,Djavad Mowafaghian Center for Brain Health, University of British Columbia, Vancouver, BC, Canada.,Department of Anesthesiology and Critical Care Medicine, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Stuart M Cain
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada.,Djavad Mowafaghian Center for Brain Health, University of British Columbia, Vancouver, BC, Canada
| | - Terrance P Snutch
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada.,Djavad Mowafaghian Center for Brain Health, University of British Columbia, Vancouver, BC, Canada
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40
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B Hughes R, Whittingham-Dowd J, Simmons RE, Clapcote SJ, Broughton SJ, Dawson N. Ketamine Restores Thalamic-Prefrontal Cortex Functional Connectivity in a Mouse Model of Neurodevelopmental Disorder-Associated 2p16.3 Deletion. Cereb Cortex 2020; 30:2358-2371. [PMID: 31812984 PMCID: PMC7175007 DOI: 10.1093/cercor/bhz244] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Revised: 05/01/2019] [Accepted: 06/24/2019] [Indexed: 12/20/2022] Open
Abstract
2p16.3 deletions, involving heterozygous NEUREXIN1 (NRXN1) deletion, dramatically increase the risk of developing neurodevelopmental disorders, including autism and schizophrenia. We have little understanding of how NRXN1 heterozygosity increases the risk of developing these disorders, particularly in terms of the impact on brain and neurotransmitter system function and brain network connectivity. Thus, here we characterize cerebral metabolism and functional brain network connectivity in Nrxn1α heterozygous mice (Nrxn1α+/- mice), and assess the impact of ketamine and dextro-amphetamine on cerebral metabolism in these animals. We show that heterozygous Nrxn1α deletion alters cerebral metabolism in neural systems implicated in autism and schizophrenia including the thalamus, mesolimbic system, and select cortical regions. Nrxn1α heterozygosity also reduces the efficiency of functional brain networks, through lost thalamic "rich club" and prefrontal cortex (PFC) hub connectivity and through reduced thalamic-PFC and thalamic "rich club" regional interconnectivity. Subanesthetic ketamine administration normalizes the thalamic hypermetabolism and partially normalizes thalamic disconnectivity present in Nrxn1α+/- mice, while cerebral metabolic responses to dextro-amphetamine are unaltered. The data provide new insight into the systems-level impact of heterozygous Nrxn1α deletion and how this increases the risk of developing neurodevelopmental disorders. The data also suggest that the thalamic dysfunction induced by heterozygous Nrxn1α deletion may be NMDA receptor-dependent.
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Affiliation(s)
- Rebecca B Hughes
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster LA1 4YQ, UK
| | - Jayde Whittingham-Dowd
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster LA1 4YQ, UK
| | - Rachel E Simmons
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster LA1 4YQ, UK
| | - Steven J Clapcote
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Susan J Broughton
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster LA1 4YQ, UK
| | - Neil Dawson
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster LA1 4YQ, UK
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Dolphin AC, Lee A. Presynaptic calcium channels: specialized control of synaptic neurotransmitter release. Nat Rev Neurosci 2020; 21:213-229. [PMID: 32161339 PMCID: PMC7873717 DOI: 10.1038/s41583-020-0278-2] [Citation(s) in RCA: 126] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/12/2020] [Indexed: 11/09/2022]
Abstract
Chemical synapses are heterogeneous junctions formed between neurons that are specialized for the conversion of electrical impulses into the exocytotic release of neurotransmitters. Voltage-gated Ca2+ channels play a pivotal role in this process as they are the major conduits for the Ca2+ ions that trigger the fusion of neurotransmitter-containing vesicles with the presynaptic membrane. Alterations in the intrinsic function of these channels and their positioning within the active zone can profoundly alter the timing and strength of synaptic output. Advances in optical and electron microscopic imaging, structural biology and molecular techniques have facilitated recent breakthroughs in our understanding of the properties of voltage-gated Ca2+ channels that support their presynaptic functions. Here we examine the nature of these channels, how they are trafficked to and anchored within presynaptic boutons, and the mechanisms that allow them to function optimally in shaping the flow of information through neural circuits.
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Affiliation(s)
- Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK.
| | - Amy Lee
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, USA.
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Luo F, Sclip A, Jiang M, Südhof TC. Neurexins cluster Ca 2+ channels within the presynaptic active zone. EMBO J 2020; 39:e103208. [PMID: 32134527 PMCID: PMC7110102 DOI: 10.15252/embj.2019103208] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 01/30/2020] [Accepted: 02/03/2020] [Indexed: 02/05/2023] Open
Abstract
To achieve ultrafast neurotransmission, neurons assemble synapses with highly organized presynaptic and postsynaptic nanomachines that are aligned by synaptic adhesion molecules. How functional assembly of presynaptic active zones is controlled via trans-synaptic interactions remains unknown. Here, we conditionally deleted all three neurexin adhesion molecules from presynaptic neurons of the calyx of Held in the mouse auditory system, a model synapse that allows precise biophysical analyses of synaptic properties. The pan-neurexin deletion had no effect on synapse development or the basic release machinery, but dramatically impaired fast neurotransmitter release. The overall properties of presynaptic calcium ion channels appeared normal, as reflected by the similar characteristics of calcium currents recorded at the nerve terminals. However, the pan-neurexin deletion significantly impaired the tight coupling of calcium influx to exocytosis, thereby suppressing neurotransmitter release. Furthermore, the pan-neurexin deletion reduced the function of calcium-activated BK potassium channels, whose activation depends on their tight association with presynaptic calcium channels. Together, these results suggest that neurexins perform a major function at the calyx synapse in coupling presynaptic calcium channels to release sites.
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Affiliation(s)
- Fujun Luo
- Department of Molecular and Cellular PhysiologyHoward Hughes Medical InstituteStanford University Medical SchoolStanfordCAUSA
| | - Alessandra Sclip
- Department of Molecular and Cellular PhysiologyHoward Hughes Medical InstituteStanford University Medical SchoolStanfordCAUSA
| | - Man Jiang
- Department of Molecular and Cellular PhysiologyHoward Hughes Medical InstituteStanford University Medical SchoolStanfordCAUSA
| | - Thomas C Südhof
- Department of Molecular and Cellular PhysiologyHoward Hughes Medical InstituteStanford University Medical SchoolStanfordCAUSA
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α2δ-2 Protein Controls Structure and Function at the Cerebellar Climbing Fiber Synapse. J Neurosci 2020; 40:2403-2415. [PMID: 32086258 DOI: 10.1523/jneurosci.1514-19.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 12/18/2019] [Accepted: 01/07/2020] [Indexed: 12/14/2022] Open
Abstract
α2δ proteins (Cacna2d1-4) are auxiliary subunits of voltage-dependent calcium channels that also drive synapse formation and maturation. Because cerebellar Purkinje cells (PCs) predominantly, if not exclusively, express one isoform of this family, α2δ-2 (Cacna2d2), we used PCs as a model system to examine roles of α2δ in excitatory synaptic function in male and female Cacna2d2 knock-out (KO) mice. Whole-cell recordings of PCs from acute cerebellar slices revealed altered climbing fiber (CF)-evoked complex spike generation, as well as increased amplitude and faster decay of CF-evoked EPSCs. CF terminals in the KO were localized more proximally on PC dendrites, as indicated by VGLUT2+ immunoreactive puncta, and computational modeling demonstrated that the increased EPSC amplitude can be partly attributed to the more proximal location of CF terminals. In addition, CFs in KO mice exhibited increased multivesicular transmission, corresponding to greater sustained responses during repetitive stimulation, despite a reduction in the measured probability of release. Electron microscopy demonstrated that mutant CF terminals had twice as many vesicle release sites, providing a morphologic explanation for the enhanced glutamate release. Though KO CFs evoked larger amplitude EPSCs, the charge transfer was the same as wild-type as a result of increased glutamate reuptake, producing faster decay kinetics. Together, the larger, faster EPSCs in the KO explain the altered complex spike responses, which degrade information transfer from PCs and likely contribute to ataxia in Cacna2d2 KO mice. Our results also illustrate the multidimensional synaptic roles of α2δ proteins.SIGNIFICANCE STATEMENT α2δ proteins (Cacna2d1-4) regulate synaptic transmission and synaptogenesis, but coexpression of multiple α2δ isoforms has obscured a clear understanding of how various α2δ proteins control synaptic function. We focused on roles of the α2δ-2 protein (Cacna2d2), the deletion of which causes cerebellar ataxia and epilepsy in mice and humans. Because cerebellar Purkinje cells (PCs) only express this single isoform, we studied excitatory climbing fiber synaptic function onto PCs in Cacna2d2 KO mice. Using optical and electrophysiological analysis, we provide a detailed description of the changes in PCs lacking α2δ-2, and provide a comprehensive mechanistic explanation for how functional synaptic phenotypes contribute to the altered cerebellar output.
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Avazzadeh S, McDonagh K, Reilly J, Wang Y, Boomkamp SD, McInerney V, Krawczyk J, Fitzgerald J, Feerick N, O'Sullivan M, Jalali A, Forman EB, Lynch SA, Ennis S, Cosemans N, Peeters H, Dockery P, O'Brien T, Quinlan LR, Gallagher L, Shen S. Increased Ca 2+ signaling in NRXN1α +/- neurons derived from ASD induced pluripotent stem cells. Mol Autism 2019; 10:52. [PMID: 31893021 PMCID: PMC6937972 DOI: 10.1186/s13229-019-0303-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 12/05/2019] [Indexed: 12/28/2022] Open
Abstract
Background Autism spectrum disorder (ASD) is a neurodevelopmental disorder with a high co-morbidity of epilepsy and associated with hundreds of rare risk factors. NRXN1 deletion is among the commonest rare genetic factors shared by ASD, schizophrenia, intellectual disability, epilepsy, and developmental delay. However, how NRXN1 deletions lead to different clinical symptoms is unknown. Patient-derived cells are essential to investigate the functional consequences of NRXN1 lesions to human neurons in different diseases. Methods Skin biopsies were donated by five healthy donors and three ASD patients carrying NRXN1α+/− deletions. Seven control and six NRXN1α+/− iPSC lines were derived and differentiated into day 100 cortical excitatory neurons using dual SMAD inhibition. Calcium (Ca2+) imaging was performed using Fluo4-AM, and the properties of Ca2+ transients were compared between two groups of neurons. Transcriptome analysis was carried out to undercover molecular pathways associated with NRXN1α+/− neurons. Results NRXN1α+/− neurons were found to display altered calcium dynamics, with significantly increased frequency, duration, and amplitude of Ca2+ transients. Whole genome RNA sequencing also revealed altered ion transport and transporter activity, with upregulated voltage-gated calcium channels as one of the most significant pathways in NRXN1α+/− neurons identified by STRING and GSEA analyses. Conclusions This is the first report to show that human NRXN1α+/− neurons derived from ASD patients’ iPSCs present novel phenotypes of upregulated VGCCs and increased Ca2+ transients, which may facilitate the development of drug screening assays for the treatment of ASD.
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Affiliation(s)
- Sahar Avazzadeh
- 1Regenerative Medicine Institute, School of Medicine, Biomedical Science Building BMS-1021, National University of Ireland Galway, Dangan, Upper Newcastle, Galway, Ireland
| | - Katya McDonagh
- 1Regenerative Medicine Institute, School of Medicine, Biomedical Science Building BMS-1021, National University of Ireland Galway, Dangan, Upper Newcastle, Galway, Ireland
| | - Jamie Reilly
- 1Regenerative Medicine Institute, School of Medicine, Biomedical Science Building BMS-1021, National University of Ireland Galway, Dangan, Upper Newcastle, Galway, Ireland
| | - Yanqin Wang
- 1Regenerative Medicine Institute, School of Medicine, Biomedical Science Building BMS-1021, National University of Ireland Galway, Dangan, Upper Newcastle, Galway, Ireland.,2Department of Physiology, College of Life Science, Hebei Normal University, Shijiazhuang, China
| | - Stephanie D Boomkamp
- 1Regenerative Medicine Institute, School of Medicine, Biomedical Science Building BMS-1021, National University of Ireland Galway, Dangan, Upper Newcastle, Galway, Ireland
| | - Veronica McInerney
- 3HRB Clinical Research Facility, National University of Ireland (NUI), Galway, Ireland
| | - Janusz Krawczyk
- 4Department of Haematology, Galway University Hospital, Galway, Ireland
| | | | - Niamh Feerick
- 5School of Medicine, Trinity College Dublin, Dublin, Ireland
| | | | - Amirhossein Jalali
- 6School of Medicine, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Eva B Forman
- 7Children's University Hospital, Temple Street, Dublin, Ireland
| | - Sally A Lynch
- Department of Clinical Genetics, OLCHC, Dublin 12, Ireland.,9Children's University Hospital, Temple St, Dublin, Ireland.,10Academic Center on Rare Diseases, School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Sean Ennis
- 11UCD Academic Centre on Rare Diseases, School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Nele Cosemans
- 12Centre for Human Genetics, University Hospital Leuven, KU Leuven, 3000 Leuven, Belgium
| | - Hilde Peeters
- 10Academic Center on Rare Diseases, School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Peter Dockery
- 13Centre for Microscopy and Imaging, Anatomy, School of Medicine, National University of Ireland (NUI), Galway, Ireland
| | - Timothy O'Brien
- 1Regenerative Medicine Institute, School of Medicine, Biomedical Science Building BMS-1021, National University of Ireland Galway, Dangan, Upper Newcastle, Galway, Ireland
| | - Leo R Quinlan
- 14Physiology and Human Movement Laboratory, CÚRAM SFI Centre for Research in Medical Devices, School of Medicine, National University of Ireland (NUI), Galway, Ireland
| | | | - Sanbing Shen
- 1Regenerative Medicine Institute, School of Medicine, Biomedical Science Building BMS-1021, National University of Ireland Galway, Dangan, Upper Newcastle, Galway, Ireland
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45
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Hoover KM, Gratz SJ, Qi N, Herrmann KA, Liu Y, Perry-Richardson JJ, Vanderzalm PJ, O'Connor-Giles KM, Broihier HT. The calcium channel subunit α 2δ-3 organizes synapses via an activity-dependent and autocrine BMP signaling pathway. Nat Commun 2019; 10:5575. [PMID: 31811118 PMCID: PMC6898181 DOI: 10.1038/s41467-019-13165-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 10/23/2019] [Indexed: 12/17/2022] Open
Abstract
Synapses are highly specialized for neurotransmitter signaling, yet activity-dependent growth factor release also plays critical roles at synapses. While efficient neurotransmitter signaling relies on precise apposition of release sites and neurotransmitter receptors, molecular mechanisms enabling high-fidelity growth factor signaling within the synaptic microenvironment remain obscure. Here we show that the auxiliary calcium channel subunit α2δ-3 promotes the function of an activity-dependent autocrine Bone Morphogenetic Protein (BMP) signaling pathway at the Drosophila neuromuscular junction (NMJ). α2δ proteins have conserved synaptogenic activity, although how they execute this function has remained elusive. We find that α2δ-3 provides an extracellular scaffold for an autocrine BMP signal, suggesting a mechanistic framework for understanding α2δ's conserved role in synapse organization. We further establish a transcriptional requirement for activity-dependent, autocrine BMP signaling in determining synapse density, structure, and function. We propose that activity-dependent, autocrine signals provide neurons with continuous feedback on their activity state for modulating both synapse structure and function.
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Affiliation(s)
- Kendall M Hoover
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Scott J Gratz
- Department of Neuroscience, Brown University, Providence, RI, 02912, USA
| | - Nova Qi
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Kelsey A Herrmann
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Yizhou Liu
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Jahci J Perry-Richardson
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Pamela J Vanderzalm
- Department of Biology, John Carroll University, University Heights, OH, 44118, USA
| | | | - Heather T Broihier
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
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46
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Martínez San Segundo P, Terni B, Burgueño J, Monroy X, Dordal A, Merlos M, Llobet A. Outside-in regulation of the readily releasable pool of synaptic vesicles by α2δ-1. FASEB J 2019; 34:1362-1377. [PMID: 31914622 DOI: 10.1096/fj.201901551r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 10/09/2019] [Accepted: 10/23/2019] [Indexed: 12/17/2022]
Abstract
The readily releasable pool (RRP) of synaptic vesicles is a key determinant of phasic neurotransmission. Although the size of the RRP is tightly regulated by intracellular factors, there is little evidence for its modification by extracellular signals. By studying the homogeneous population of synapses present in autaptic microcultures, we show that pregabalin, a prototypical gabapentinoid, decreases the effective RRP size. Simultaneous imaging of presynaptic calcium influx and recording of postsynaptic responses shows that the effect is not related to a reduction of calcium entry. The main cause is the impairment of the functional coupling among N-type calcium channels and the RRP, resembling an increase of intracellular mobile calcium buffers. The ectodomain of neurexin-1α shows a similar action to pregabalin, acting as an endogenous ligand of α2δ-1 that reduces the RRP size without affecting presynaptic calcium influx. The regulatory actions described for pregabalin and the ectodomain of neurexin-1α are mutually exclusive. The overexpression of α2δ-1 enhances the effect of pregabalin and the ectodomain of neurexin-1α on neurotransmission by decreasing their effective concentration. In contrast, knockdown of α2δ-1 causes a profound inhibition of synaptic transmission. These observations prompt to consider α2δ-1 as an outside-in signaling platform that binds exogenous and endogenous cues for regulating the coupling of voltage-gated calcium channels to synaptic vesicles.
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Affiliation(s)
- Pablo Martínez San Segundo
- Laboratory of Neurobiology, Bellvitge Biomedical Research Institute (IDIBELL), Barcelona, Spain.,Department of Pathology and Experimental Therapeutics, School of Medicine, Institute of Neurosciences, University of Barcelona, Barcelona, Spain
| | - Beatrice Terni
- Laboratory of Neurobiology, Bellvitge Biomedical Research Institute (IDIBELL), Barcelona, Spain.,Department of Pathology and Experimental Therapeutics, School of Medicine, Institute of Neurosciences, University of Barcelona, Barcelona, Spain
| | - Javier Burgueño
- Department of Pharmacology, Drug Discovery and Preclinical Development, ESTEVE, Barcelona, Spain
| | - Xavier Monroy
- Department of Pharmacology, Drug Discovery and Preclinical Development, ESTEVE, Barcelona, Spain
| | - Albert Dordal
- Department of Pharmacology, Drug Discovery and Preclinical Development, ESTEVE, Barcelona, Spain
| | - Manuel Merlos
- Department of Pharmacology, Drug Discovery and Preclinical Development, ESTEVE, Barcelona, Spain
| | - Artur Llobet
- Laboratory of Neurobiology, Bellvitge Biomedical Research Institute (IDIBELL), Barcelona, Spain.,Department of Pathology and Experimental Therapeutics, School of Medicine, Institute of Neurosciences, University of Barcelona, Barcelona, Spain
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47
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Hu Z, Xiao X, Zhang Z, Li M. Genetic insights and neurobiological implications from NRXN1 in neuropsychiatric disorders. Mol Psychiatry 2019; 24:1400-1414. [PMID: 31138894 DOI: 10.1038/s41380-019-0438-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 03/31/2019] [Accepted: 04/29/2019] [Indexed: 02/08/2023]
Abstract
Many neuropsychiatric and neurodevelopmental disorders commonly share genetic risk factors. To date, the mechanisms driving the pathogenesis of these disorders, particularly how genetic variations affect the function of risk genes and contribute to disease symptoms, remain largely unknown. Neurexins are a family of synaptic adhesion molecules, which play important roles in the formation and establishment of synaptic structure, as well as maintenance of synaptic function. Accumulating genomic findings reveal that genetic variations within genes encoding neurexins are associated with a variety of psychiatric conditions such as schizophrenia, autism spectrum disorder, and some developmental abnormalities. In this review, we focus on NRXN1, one of the most compelling psychiatric risk genes of the neurexin family. We performed a comprehensive survey and analysis of current genetic and molecular data including both common and rare alleles within NRXN1 associated with psychiatric illnesses, thus providing insights into the genetic risk conferred by NRXN1. We also summarized the neurobiological evidences, supporting the function of NRXN1 and its protein products in synaptic formation, organization, transmission and plasticity, as well as disease-relevant behaviors, and assessed the mechanistic link between the mutations of NRXN1 and synaptic and behavioral pathology in neuropsychiatric disorders.
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Affiliation(s)
- Zhonghua Hu
- Institute of Molecular Precision Medicine and Hunan Key Laboratory of Molecular Precision Medicine, Xiangya Hospital, Central South University, Changsha, Hunan, China. .,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China. .,Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China. .,Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, Hunan, China. .,Department of Psychiatry, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China. .,National Clinical Research Center on Mental Disorders, Changsha, Hunan, China.
| | - Xiao Xiao
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Zhuohua Zhang
- Institute of Molecular Precision Medicine and Hunan Key Laboratory of Molecular Precision Medicine, Xiangya Hospital, Central South University, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, Hunan, China
| | - Ming Li
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China. .,CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.
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48
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Andrade A, Brennecke A, Mallat S, Brown J, Gomez-Rivadeneira J, Czepiel N, Londrigan L. Genetic Associations between Voltage-Gated Calcium Channels and Psychiatric Disorders. Int J Mol Sci 2019; 20:E3537. [PMID: 31331039 PMCID: PMC6679227 DOI: 10.3390/ijms20143537] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/12/2019] [Accepted: 07/13/2019] [Indexed: 12/23/2022] Open
Abstract
Psychiatric disorders are mental, behavioral or emotional disorders. These conditions are prevalent, one in four adults suffer from any type of psychiatric disorders world-wide. It has always been observed that psychiatric disorders have a genetic component, however, new methods to sequence full genomes of large cohorts have identified with high precision genetic risk loci for these conditions. Psychiatric disorders include, but are not limited to, bipolar disorder, schizophrenia, autism spectrum disorder, anxiety disorders, major depressive disorder, and attention-deficit and hyperactivity disorder. Several risk loci for psychiatric disorders fall within genes that encode for voltage-gated calcium channels (CaVs). Calcium entering through CaVs is crucial for multiple neuronal processes. In this review, we will summarize recent findings that link CaVs and their auxiliary subunits to psychiatric disorders. First, we will provide a general overview of CaVs structure, classification, function, expression and pharmacology. Next, we will summarize tools to study risk loci associated with psychiatric disorders. We will examine functional studies of risk variations in CaV genes when available. Finally, we will review pharmacological evidence of the use of CaV modulators to treat psychiatric disorders. Our review will be of interest for those studying pathophysiological aspects of CaVs.
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Affiliation(s)
- Arturo Andrade
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA.
| | - Ashton Brennecke
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - Shayna Mallat
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - Julian Brown
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | | | - Natalie Czepiel
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - Laura Londrigan
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
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49
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Brockhaus J, Brüggen B, Missler M. Imaging and Analysis of Presynaptic Calcium Influx in Cultured Neurons Using synGCaMP6f. Front Synaptic Neurosci 2019; 11:12. [PMID: 31057389 PMCID: PMC6477507 DOI: 10.3389/fnsyn.2019.00012] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 03/26/2019] [Indexed: 12/12/2022] Open
Abstract
Presynaptic Ca2+ influx through voltage-gated calcium channels (VGCCs) is a key step in synaptic transmission that links action potential (AP)-derived depolarization to vesicle release. However, investigation of presynaptic Ca2+ influx by patch clamp recordings is difficult due to the small size of the majority of synaptic boutons along thin axons that hamper clamp control. Genetically encoded calcium indicators (GECIs) in combination with live cell imaging provide an alternative method to study Ca2+ transients in individual presynaptic terminals. The indicator GCaMP6f was developed for fast speed and high sensitivity in detecting Ca2+ transients even in subcellular compartments. We fused GCaMP6f to synaptophysin (synGCaMP6f) to enrich the calcium indicator in presynaptic boutons of transfected primary hippocampal neurons to study presynaptic Ca2+ changes in response to individual APs or short bursts. Changes in fluorescence intensity were evaluated by normalization to control level or, alternatively, by normalization to maximal fluorescence using the calcium ionophore ionomycin. Measurements revealed robust Ca2+ transients with amplitudes that depend on parameters like the number of APs, stimulation frequency or external calcium concentration. Our findings indicate an appropriate sensitivity of synGCaMP6f for studying total presynaptic Ca2+ transients induced by single APs or short bursts that showed little rundown of the response after repeated bursts. Moreover, these recordings are fast enough to even study short-term plasticity like paired pulse facilitation (PPF) and frequency dependence of Ca2+ transients. In addition, synGCaMP6f could be used to dissect the contribution of different subtypes of VGCCs to presynaptic Ca2+ influx. Our results demonstrate that synGCaMP6f allows the reliable analysis of changes in presynaptic calcium concentration at many individual synaptic boutons in parallel and provides the possibility to study the regulation of this important step in synaptic transmission.
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Affiliation(s)
- Johannes Brockhaus
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Münster, Germany
| | - Bianca Brüggen
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Münster, Germany
| | - Markus Missler
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Münster, Germany
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50
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Geisler S, Schöpf CL, Stanika R, Kalb M, Campiglio M, Repetto D, Traxler L, Missler M, Obermair GJ. Presynaptic α 2δ-2 Calcium Channel Subunits Regulate Postsynaptic GABA A Receptor Abundance and Axonal Wiring. J Neurosci 2019; 39:2581-2605. [PMID: 30683685 PMCID: PMC6445987 DOI: 10.1523/jneurosci.2234-18.2019] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 01/03/2019] [Accepted: 01/08/2019] [Indexed: 01/26/2023] Open
Abstract
Presynaptic α2δ subunits of voltage-gated calcium channels regulate channel abundance and are involved in glutamatergic synapse formation. However, little is known about the specific functions of the individual α2δ isoforms and their role in GABAergic synapses. Using primary neuronal cultures of embryonic mice of both sexes, we here report that presynaptic overexpression of α2δ-2 in GABAergic synapses strongly increases clustering of postsynaptic GABAARs. Strikingly, presynaptic α2δ-2 exerts the same effect in glutamatergic synapses, leading to a mismatched localization of GABAARs. This mismatching is caused by an aberrant wiring of glutamatergic presynaptic boutons with GABAergic postsynaptic positions. The trans-synaptic effect of α2δ-2 is independent of the prototypical cell-adhesion molecules α-neurexins (α-Nrxns); however, α-Nrxns together with α2δ-2 can modulate postsynaptic GABAAR abundance. Finally, exclusion of the alternatively spliced exon 23 of α2δ-2 is essential for the trans-synaptic mechanism. The novel function of α2δ-2 identified here may explain how abnormal α2δ subunit expression can cause excitatory-inhibitory imbalance often associated with neuropsychiatric disorders.SIGNIFICANCE STATEMENT Voltage-gated calcium channels regulate important neuronal functions such as synaptic transmission. α2δ subunits modulate calcium channels and are emerging as regulators of brain connectivity. However, little is known about how individual α2δ subunits contribute to synapse specificity. Here, we show that presynaptic expression of a single α2δ variant can modulate synaptic connectivity and the localization of inhibitory postsynaptic receptors. Our findings provide basic insights into the development of specific synaptic connections between nerve cells and contribute to our understanding of normal nerve cell functions. Furthermore, the identified mechanism may explain how an altered expression of calcium channel subunits can result in aberrant neuronal wiring often associated with neuropsychiatric disorders such as autism or schizophrenia.
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Affiliation(s)
- Stefanie Geisler
- Division of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria, and
| | - Clemens L Schöpf
- Division of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria, and
| | - Ruslan Stanika
- Division of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria, and
| | - Marcus Kalb
- Division of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria, and
| | - Marta Campiglio
- Division of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria, and
| | - Daniele Repetto
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, 48149 Münster, Germany
| | - Larissa Traxler
- Division of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria, and
| | - Markus Missler
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, 48149 Münster, Germany
| | - Gerald J Obermair
- Division of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria, and
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