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Marshall AH, Boyle DJ, Hanson MA, Nagarajan D, Bibi N, Safa A, Johantges AC, Wester JC. Arid1b haploinsufficiency in cortical inhibitory interneurons causes cell-type-dependent changes in cellular and synaptic development. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.07.597984. [PMID: 38895260 PMCID: PMC11185764 DOI: 10.1101/2024.06.07.597984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Autism spectrum disorder (ASD) presents with diverse cognitive and behavioral abnormalities beginning during early development. Although the neural circuit mechanisms remain unclear, recent work suggests pathology in cortical inhibitory interneurons (INs) plays a crucial role. However, we lack fundamental information regarding changes in the physiology of synapses to and from INs in ASD. Here, we used transgenic mice to conditionally knockout one copy of the high confidence ASD risk gene Arid1b from the progenitors of parvalbumin-expressing fast-spiking (PV-FS) INs and somatostatin-expressing non-fast-spiking (SST-NFS) INs. In brain slices, we performed paired whole-cell recordings between INs and excitatory projection neurons (PNs) to investigate changes in synaptic physiology. In neonates, we found reduced synaptic input to INs but not PNs, with a concomitant reduction in the frequency of spontaneous network events, which are driven by INs in immature circuits. In mature mice, we found a reduction in the number of PV-FS INs in cortical layers 2/3 and 5. However, changes in PV-FS IN synaptic physiology were cortical layer and PN cell-type dependent. In layer 5, synapses from PV-FS INs to subcortical-projecting PNs were weakened. In contrast, in layer 2/3, synapses to and from PV-FS INs and corticocortical-projecting PNs were strengthened, leading to enhanced feedforward inhibition of input from layer 4. Finally, we found a novel synaptic deficit among SST-NFS INs, in which excitatory synapses from layer 2/3 PNs failed to facilitate. Our data highlight that changes in unitary synaptic dynamics among INs in ASD depend on neuronal cell-type.
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Gonzalez-Hernandez AJ, Munguba H, Levitz J. Emerging modes of regulation of neuromodulatory G protein-coupled receptors. Trends Neurosci 2024:S0166-2236(24)00088-2. [PMID: 38862331 DOI: 10.1016/j.tins.2024.05.008] [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: 03/28/2024] [Revised: 05/16/2024] [Accepted: 05/21/2024] [Indexed: 06/13/2024]
Abstract
In the nervous system, G protein-coupled receptors (GPCRs) control neuronal excitability, synaptic transmission, synaptic plasticity, and, ultimately, behavior through spatiotemporally precise initiation of a variety of signaling pathways. However, despite their critical importance, there is incomplete understanding of how these receptors are regulated to tune their signaling to specific neurophysiological contexts. A deeper mechanistic picture of neuromodulatory GPCR function is needed to fully decipher their biological roles and effectively harness them for the treatment of neurological and psychiatric disorders. In this review, we highlight recent progress in identifying novel modes of regulation of neuromodulatory GPCRs, including G protein- and receptor-targeting mechanisms, receptor-receptor crosstalk, and unique features that emerge in the context of chemical synapses. These emerging principles of neuromodulatory GPCR tuning raise critical questions to be tackled at the molecular, cellular, synaptic, and neural circuit levels in the future.
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Affiliation(s)
| | - Hermany Munguba
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA; Department of Psychiatry, Weill Cornell Medicine, New York, NY 10065, USA
| | - Joshua Levitz
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA; Department of Psychiatry, Weill Cornell Medicine, New York, NY 10065, USA.
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3
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Ferranti AS, Luessen DJ, Niswender CM. Novel pharmacological targets for GABAergic dysfunction in ADHD. Neuropharmacology 2024; 249:109897. [PMID: 38462041 DOI: 10.1016/j.neuropharm.2024.109897] [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: 01/01/2024] [Revised: 02/26/2024] [Accepted: 03/04/2024] [Indexed: 03/12/2024]
Abstract
Attention deficit/hyperactivity disorder (ADHD) is a neurodevelopment disorder that affects approximately 5% of the population. The disorder is characterized by impulsivity, hyperactivity, and deficits in attention and cognition, although symptoms vary across patients due to the heterogenous and polygenic nature of the disorder. Stimulant medications are the standard of care treatment for ADHD patients, and their effectiveness has led to the dopaminergic hypothesis of ADHD in which deficits in dopaminergic signaling, especially in cortical brain regions, mechanistically underly ADHD pathophysiology. Despite their effectiveness in many individuals, almost one-third of patients do not respond to stimulant treatments and the long-term negative side effects of these medications remain unclear. Emerging clinical evidence is beginning to highlight an important role of dysregulated excitatory/inhibitory (E/I) balance in ADHD. These deficits in E/I balance are related to functional abnormalities in glutamate and Gamma-Aminobutyric Acid (GABA) signaling in the brain, with increasing emphasis placed on GABAergic interneurons driving specific aspects of ADHD pathophysiology. Recent genome-wide association studies (GWAS) have also highlighted how genes associated with GABA function are mutated in human populations with ADHD, resulting in the generation of several new genetic mouse models of ADHD. This review will discuss how GABAergic dysfunction underlies ADHD pathophysiology, and how specific receptors/proteins related to GABAergic interneuron dysfunction may be pharmacologically targeted to treat ADHD in subpopulations with specific comorbidities and symptom domains. This article is part of the Special Issue on "PFC circuit function in psychiatric disease and relevant models".
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Affiliation(s)
- Anthony S Ferranti
- Department of Pharmacology, Vanderbilt University, Nashville, TN, 37232, USA; Warren Center for Neuroscience Drug Discovery, Nashville, TN, 37232, USA
| | - Deborah J Luessen
- Department of Pharmacology, Vanderbilt University, Nashville, TN, 37232, USA; Warren Center for Neuroscience Drug Discovery, Nashville, TN, 37232, USA
| | - Colleen M Niswender
- Department of Pharmacology, Vanderbilt University, Nashville, TN, 37232, USA; Warren Center for Neuroscience Drug Discovery, Nashville, TN, 37232, USA; Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN, 37232, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, 37232, USA; Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, 37232, USA.
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4
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Parent HH, Niswender CM. Therapeutic Potential for Metabotropic Glutamate Receptor 7 Modulators in Cognitive Disorders. Mol Pharmacol 2024; 105:348-358. [PMID: 38423750 PMCID: PMC11026152 DOI: 10.1124/molpharm.124.000874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 02/05/2024] [Accepted: 02/12/2024] [Indexed: 03/02/2024] Open
Abstract
Metabotropic glutamate receptor 7 (mGlu7) is the most highly conserved and abundantly expressed mGlu receptor in the human brain. The presynaptic localization of mGlu7, coupled with its low affinity for its endogenous agonist, glutamate, are features that contribute to the receptor's role in modulating neuronal excitation and inhibition patterns, including long-term potentiation, in various brain regions. These characteristics suggest that mGlu7 modulation may serve as a novel therapeutic strategy in disorders of cognitive dysfunction, including neurodevelopmental disorders that cause impairments in learning, memory, and attention. Primary mutations in the GRM7 gene have recently been identified as novel causes of neurodevelopmental disorders, and these patients exhibit profound intellectual and cognitive disability. Pharmacological tools, such as agonists, antagonists, and allosteric modulators, have been the mainstay for targeting mGlu7 in its endogenous homodimeric form to probe effects of its function and modulation in disease models. However, recent research has identified diversity in dimerization, as well as trans-synaptic interacting proteins, that also play a role in mGlu7 signaling and pharmacological properties. These novel findings represent exciting opportunities in the field of mGlu receptor drug discovery and highlight the importance of further understanding the functions of mGlu7 in complex neurologic conditions at both the molecular and physiologic levels. SIGNIFICANCE STATEMENT: Proper expression and function of mGlu7 is essential for learning, attention, and memory formation at the molecular level within neural circuits. The pharmacological targeting of mGlu7 is undergoing a paradigm shift by incorporating an understanding of receptor interaction with other cis- and trans- acting synaptic proteins, as well as various intracellular signaling pathways. Based upon these new findings, mGlu7's potential as a drug target in the treatment of cognitive disorders and learning impairments is primed for exploration.
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Affiliation(s)
- Harrison H Parent
- Department of Pharmacology (H.H.P., C.M.N.), Warren Center for Neuroscience Drug Discovery (H.H.P., C.M.N.), Vanderbilt Brain Institute (C.M.N.), and Vanderbilt Institute for Chemical Biology (C.M.N.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee (C.M.N.)
| | - Colleen M Niswender
- Department of Pharmacology (H.H.P., C.M.N.), Warren Center for Neuroscience Drug Discovery (H.H.P., C.M.N.), Vanderbilt Brain Institute (C.M.N.), and Vanderbilt Institute for Chemical Biology (C.M.N.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee (C.M.N.)
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5
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Miller ML, Pindwarawala M, Agosto MA. Complex N-glycosylation of mGluR6 is required for trans-synaptic interaction with ELFN adhesion proteins. J Biol Chem 2024; 300:107119. [PMID: 38428819 PMCID: PMC10973816 DOI: 10.1016/j.jbc.2024.107119] [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: 11/09/2023] [Revised: 01/30/2024] [Accepted: 02/16/2024] [Indexed: 03/03/2024] Open
Abstract
Synaptic transmission from retinal photoreceptors to downstream ON-type bipolar cells (BCs) depends on the postsynaptic metabotropic glutamate receptor mGluR6, located at the BC dendritic tips. Glutamate binding to mGluR6 initiates G-protein signaling that ultimately leads to BC depolarization in response to light. The mGluR6 receptor also engages in trans-synaptic interactions with presynaptic ELFN adhesion proteins. The roles of post-translational modifications in mGluR6 trafficking and function are unknown. Treatment with glycosidase enzymes PNGase F and Endo H demonstrated that both endogenous and heterologously expressed mGluR6 contain complex N-glycosylation acquired in the Golgi. Pull-down experiments with ELFN1 and ELFN2 extracellular domains revealed that these proteins interact exclusively with the complex glycosylated form of mGluR6. Mutation of the four predicted N-glycosylation sites, either singly or in combination, revealed that all four sites are glycosylated. Single mutations partially reduced, but did not abolish, surface expression in heterologous cells, while triple mutants had little or no surface expression, indicating that no single glycosylation site is necessary or sufficient for plasma membrane trafficking. Mutation at N445 severely impaired both ELFN1 and ELFN2 binding. All single mutants exhibited dendritic tip enrichment in rod BCs, as did the triple mutant with N445 as the sole N-glycosylation site, demonstrating that glycosylation at N445 is sufficient but not necessary for dendritic tip localization. The quadruple mutant was completely mislocalized. These results reveal a key role for complex N-glycosylation in regulating mGluR6 trafficking and ELFN binding, and by extension, function of the photoreceptor synapses.
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Affiliation(s)
- Michael L Miller
- Faculty of Science, Medical Sciences Program, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Mustansir Pindwarawala
- Faculty of Science, Medical Sciences Program, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Melina A Agosto
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada.
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6
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Latorraca NR, Sabaat S, Habrian C, Bleier J, Stanley C, Marqusee S, Isacoff EY. Domain coupling in activation of a family C GPCR. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.28.582567. [PMID: 38464305 PMCID: PMC10925283 DOI: 10.1101/2024.02.28.582567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
The G protein-coupled metabotropic glutamate receptors form homodimers and heterodimers with highly diverse responses to glutamate and varying physiological function. The molecular basis for this diversity remains poorly delineated. We employ molecular dynamics, single-molecule spectroscopy, and hydrogen-deuterium exchange to dissect the pathway of activation triggered by glutamate. We find that activation entails multiple loosely coupled steps and identify a novel pre-active intermediate whose transition to the active state forms dimer interactions that set signaling efficacy. Such subunit interactions generate functional diversity that differs across homodimers and heterodimers. The agonist-bound receptor is remarkably dynamic, with low occupancy of G protein-coupling conformations, providing considerable headroom for modulation of the landscape by allosteric ligands. Sites of sequence diversity within the dimerization interface and diverse coupling between activation rearrangements may contribute to precise decoding of glutamate signals and transients over broad spatial and temporal scales.
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Affiliation(s)
- Naomi R. Latorraca
- Department of Molecular and Cell Biology, University of California, Berkeley, California, 94720, USA
| | - Sam Sabaat
- Department of Molecular and Cell Biology, University of California, Berkeley, California, 94720, USA
| | - Chris Habrian
- Department of Molecular and Cell Biology, University of California, Berkeley, California, 94720, USA
| | - Julia Bleier
- Department of Molecular and Cell Biology, University of California, Berkeley, California, 94720, USA
| | - Cherise Stanley
- Department of Molecular and Cell Biology, University of California, Berkeley, California, 94720, USA
| | - Susan Marqusee
- Department of Molecular and Cell Biology, University of California, Berkeley, California, 94720, USA
- Department of Chemistry, University of California, Berkeley, California, 94720 USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158
- California Institute for Quantitative Biosciences, University of California, Berkeley, California, 94720 USA
| | - Ehud Y. Isacoff
- Department of Molecular and Cell Biology, University of California, Berkeley, California, 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, California, 94720 USA
- Molecular Biology & Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
- Weill Neurohub, University of California, Berkeley, California, 94720 USA
- Molecular Biology & Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
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7
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Januel L, Chatron N, Rivier-Ringenbach C, Cabet S, Labalme A, Sahin Y, Darvish H, Kruer M, Bakhtiari S, Sanlaville D, de Sainte Agathe JM, Lesca G. GRM7-related disorder: five additional patients from three independent families and review of the literature. Eur J Med Genet 2024; 67:104893. [PMID: 38070825 DOI: 10.1016/j.ejmg.2023.104893] [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: 06/07/2023] [Revised: 10/22/2023] [Accepted: 12/03/2023] [Indexed: 12/19/2023]
Abstract
Developmental and epileptic encephalopathies (DEEs) refer to a group of severe epileptic syndromes characterized by seizures as well as a developmental delay which can be a consequence of the underlying etiology and/or the epileptic encephalopathy. The genes responsible for DEEs are numerous and their number is increasing since the availability of Next-Generation Sequencing. Pathogenic variants in GRM7, encoding the metabotropic glutamate receptor 7, were recently shown as a cause of a severe DEE with autosomal recessive inheritance. To date, only ten patients have been reported in the literature, generally with severe phenotypes including early-onset epilepsy, microcephaly, brain anomalies, and spasticity. We report here 5 patients from 3 independent families with biallelic variants in the GRM7 gene. We review the literature and provide further elements for the understanding of the genotype-phenotype correlation of this rare syndrome.
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Affiliation(s)
- Louis Januel
- Hospices Civils de Lyon, Groupe Hospitalier Est, Service de Génétique, Bron, France.
| | - Nicolas Chatron
- Hospices Civils de Lyon, Groupe Hospitalier Est, Service de Génétique, Bron, France; Institut NeuroMyoGene PNMG, CNRS UMR5310, INSERM U1217, Université Claude Bernard Lyon 1, Lyon, France
| | | | - Sara Cabet
- Hospices Civils de Lyon, Groupe Hospitalier Est, Service de Radiologie, Bron, France
| | - Audrey Labalme
- Hospices Civils de Lyon, Groupe Hospitalier Est, Service de Génétique, Bron, France
| | | | - Hossein Darvish
- Pediatric Movement Disorders Program, Division of Pediatric Neurology, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ, USA
| | - Michael Kruer
- Pediatric Movement Disorders Program, Division of Pediatric Neurology, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ, USA
| | - Somayeh Bakhtiari
- Pediatric Movement Disorders Program, Division of Pediatric Neurology, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ, USA
| | - Damien Sanlaville
- Hospices Civils de Lyon, Groupe Hospitalier Est, Service de Génétique, Bron, France; Institut NeuroMyoGene PNMG, CNRS UMR5310, INSERM U1217, Université Claude Bernard Lyon 1, Lyon, France
| | | | - Gaetan Lesca
- Hospices Civils de Lyon, Groupe Hospitalier Est, Service de Génétique, Bron, France; Institut NeuroMyoGene PNMG, CNRS UMR5310, INSERM U1217, Université Claude Bernard Lyon 1, Lyon, France
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8
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Akçimen F, Chia R, Saez-Atienzar S, Ruffo P, Rasheed M, Ross JP, Liao C, Ray A, Dion PA, Scholz SW, Rouleau GA, Traynor BJ. Genomic analysis identifies risk factors in restless legs syndrome. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.12.19.23300211. [PMID: 38168192 PMCID: PMC10760278 DOI: 10.1101/2023.12.19.23300211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Restless legs syndrome (RLS) is a neurological condition that causes uncomfortable sensations in the legs and an irresistible urge to move them, typically during periods of rest. The genetic basis and pathophysiology of RLS are incompletely understood. Here, we present a whole-genome sequencing and genome-wide association meta-analysis of RLS cases (n = 9,851) and controls (n = 38,957) in three population-based biobanks (All of Us, Canadian Longitudinal Study on Aging, and CARTaGENE). Genome-wide association analysis identified nine independent risk loci, of which eight had been previously reported, and one was a novel risk locus (LMX1B, rs35196838, OR = 1.14, 95% CI = 1.09-1.19, p-value = 2.2 × 10-9). A genome-wide, gene-based common variant analysis identified GLO1 as an additional risk gene (p-value = 8.45 × 10-7). Furthermore, a transcriptome-wide association study also identified GLO1 and a previously unreported gene, ELFN1. A genetic correlation analysis revealed significant common variant overlaps between RLS and neuroticism (rg = 0.40, se = 0.08, p-value = 5.4 × 10-7), depression (rg = 0.35, se = 0.06, p-value = 2.17 × 10-8), and intelligence (rg = -0.20, se = 0.06, p-value = 4.0 × 10-4). Our study expands the understanding of the genetic architecture of RLS and highlights the contributions of common variants to this prevalent neurological disorder.
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Affiliation(s)
- Fulya Akçimen
- Neuromuscular Diseases Research Section, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
| | - Ruth Chia
- Neuromuscular Diseases Research Section, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
| | - Sara Saez-Atienzar
- Neuromuscular Diseases Research Section, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
| | - Paola Ruffo
- Neuromuscular Diseases Research Section, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
- Medical Genetics Laboratory, Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Rende, Italy
| | - Memoona Rasheed
- Neuromuscular Diseases Research Section, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
| | - Jay P. Ross
- Department of Human Genetics, McGill University, Montréal, QC, Canada
- Montreal Neurological Institute, McGill University, Montréal, QC, Canada
| | - Calwing Liao
- Analytic and Translational Genetics Unit, Department of Medicine, Massachusetts General Hospital, Boston, MA, USA
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Anindita Ray
- Neurodegenerative Diseases Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Patrick A. Dion
- Montreal Neurological Institute, McGill University, Montréal, QC, Canada
- Department of Neurology and Neurosurgery, McGill University, Montréal, QC, Canada
| | - Sonja W. Scholz
- Neurodegenerative Diseases Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
- Department of Neurology, Johns Hopkins University Medical Center, Baltimore, MD, USA
| | - Guy A. Rouleau
- Department of Human Genetics, McGill University, Montréal, QC, Canada
- Montreal Neurological Institute, McGill University, Montréal, QC, Canada
- Department of Neurology and Neurosurgery, McGill University, Montréal, QC, Canada
| | - Bryan J. Traynor
- Neuromuscular Diseases Research Section, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
- Department of Neurology, Johns Hopkins University Medical Center, Baltimore, MD, USA
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9
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Rabeh N, Hajjar B, Maraka JO, Sammanasunathan AF, Khan M, Alkhaaldi SMI, Mansour S, Almheiri RT, Hamdan H, Abd-Elrahman KS. Targeting mGluR group III for the treatment of neurodegenerative diseases. Biomed Pharmacother 2023; 168:115733. [PMID: 37862967 DOI: 10.1016/j.biopha.2023.115733] [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: 08/21/2023] [Revised: 10/11/2023] [Accepted: 10/13/2023] [Indexed: 10/22/2023] Open
Abstract
Glutamate, an excitatory neurotransmitter, is essential for neuronal function, and it acts on ionotropic or metabotropic glutamate receptors (mGluRs). A disturbance in glutamatergic signaling is a hallmark of many neurodegenerative diseases. Developing disease-modifying treatments for neurodegenerative diseases targeting glutamate receptors is a promising avenue. The understudied group III mGluR 4, 6-8 are commonly found in the presynaptic membrane, and their activation inhibits glutamate release. Thus, targeted mGluRs therapies could aid in treating neurodegenerative diseases. This review describes group III mGluRs and their pharmacological ligands in the context of amyotrophic lateral sclerosis, Parkinson's, Alzheimer's, and Huntington's diseases. Attempts to evaluate the efficacy of these drugs in clinical trials are also discussed. Despite a growing list of group III mGluR-specific pharmacological ligands, research on the use of these drugs in neurodegenerative diseases is limited, except for Parkinson's disease. Future efforts should focus on delineating the contribution of group III mGluR to neurodegeneration and developing novel ligands with superior efficacy and a favorable side effect profile for the treatment of neurodegenerative diseases.
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Affiliation(s)
- Nadia Rabeh
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates; Department of Anesthesiology, Pharmacology and Therapeutics, and Djavad Mowafaghian Center for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Baraa Hajjar
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Jude O Maraka
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Ashwin F Sammanasunathan
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Mohammed Khan
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Saif M I Alkhaaldi
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Samy Mansour
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Rashed T Almheiri
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Hamdan Hamdan
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates; Healthcare Engineering Innovation Center (HEIC), Khalifa University of Science and Technology, Abu Dhabi 127788, United Arab Emirates
| | - Khaled S Abd-Elrahman
- Department of Anesthesiology, Pharmacology and Therapeutics, and Djavad Mowafaghian Center for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada; Department of Pharmacology and Therapeutics, College of Medicine and Health Science, Khalifa University, Abu Dhabi 127788, United Arab Emirates; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria 21521, Egypt.
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10
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Stachniak TJ, Argunsah AÖ, Yang JW, Cai L, Karayannis T. Presynaptic Kainate Receptors onto Somatostatin Interneurons Are Recruited by Activity throughout Development and Contribute to Cortical Sensory Adaptation. J Neurosci 2023; 43:7101-7118. [PMID: 37709538 PMCID: PMC10601374 DOI: 10.1523/jneurosci.1461-22.2023] [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: 07/30/2022] [Revised: 08/24/2023] [Accepted: 08/30/2023] [Indexed: 09/16/2023] Open
Abstract
Somatostatin (SST) interneurons produce delayed inhibition because of the short-term facilitation of their excitatory inputs created by the expression of metabotropic glutamate receptor 7 (mGluR7) and presynaptic GluK2-containing kainate receptors (GluK2-KARs). Using mice of both sexes, we find that as synaptic facilitation at layer (L)2/3 SST cell inputs increases during the first few postnatal weeks, so does GluK2-KAR expression. Removal of sensory input by whisker trimming does not affect mGluR7 but prevents the emergence of presynaptic GluK2-KARs, which can be restored by allowing whisker regrowth or by acute calmodulin activation. Conversely, late trimming or acute inhibition of Ca2+/calmodulin-dependent protein kinase II is sufficient to reduce GluK2-KAR activity. This developmental and activity-dependent regulation also produces a specific reduction of L4 GluK2-KARs that advances in parallel with the maturation of sensory processing in L2/3. Finally, we find that removal of both GluK2-KARs and mGluR7 from the synapse eliminates short-term facilitation and reduces sensory adaptation to repetitive stimuli, first in L4 of somatosensory cortex, then later in development in L2/3. The dynamic regulation of presynaptic GluK2-KARs potentially allows for flexible scaling of late inhibition and sensory adaptation.SIGNIFICANCE STATEMENT Excitatory synapses onto somatostatin (SST) interneurons express presynaptic, calcium-permeable kainate receptors containing the GluK2 subunit (GluK2-KARs), activated by high-frequency activity. In this study we find that their presence on L2/3 SST synapses in the barrel cortex is not based on a hardwired genetic program but instead is regulated by sensory activity, in contrast to that of mGluR7. Thus, in addition to standard synaptic potentiation and depression mechanisms, excitatory synapses onto SST neurons undergo an activity-dependent presynaptic modulation that uses GluK2-KARs. Further, we present evidence that loss of the frequency-dependent synaptic components (both GluK2-KARs and mGluR7 via Elfn1 deletion) contributes to a decrease in the sensory adaptation commonly seen on repetitive stimulus presentation.
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Affiliation(s)
- Tevye J Stachniak
- Laboratory of Neural Circuit Assembly, Brain Research Institute, Neuroscience Center Zurich, University of Zurich, CH-8057 Zurich, Switzerland
| | - Ali Ö Argunsah
- Laboratory of Neural Circuit Assembly, Brain Research Institute, Neuroscience Center Zurich, University of Zurich, CH-8057 Zurich, Switzerland
| | - Jenq-Wei Yang
- Laboratory of Neural Circuit Assembly, Brain Research Institute, Neuroscience Center Zurich, University of Zurich, CH-8057 Zurich, Switzerland
| | - Linbi Cai
- Laboratory of Neural Circuit Assembly, Brain Research Institute, Neuroscience Center Zurich, University of Zurich, CH-8057 Zurich, Switzerland
| | - Theofanis Karayannis
- Laboratory of Neural Circuit Assembly, Brain Research Institute, Neuroscience Center Zurich, University of Zurich, CH-8057 Zurich, Switzerland
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11
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Shimohata A, Rai D, Akagi T, Usui S, Ogiwara I, Kaneda M. The intracellular C-terminal domain of mGluR6 contains ER retention motifs. Mol Cell Neurosci 2023; 126:103875. [PMID: 37352898 DOI: 10.1016/j.mcn.2023.103875] [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: 03/20/2023] [Revised: 06/15/2023] [Accepted: 06/19/2023] [Indexed: 06/25/2023] Open
Abstract
Metabotropic glutamate receptor 6 (mGluR6) predominantly localizes to the postsynaptic sites of retinal ON-bipolar cells, at which it recognizes glutamate released from photoreceptors. The C-terminal domain (CTD) of mGluR6 contains a cluster of basic amino acids resembling motifs for endoplasmic reticulum (ER) retention. We herein investigated whether these basic residues are involved in regulating the subcellular localization of mGluR6 in 293T cells expressing mGluR6 CTD mutants using immunocytochemistry, immunoprecipitation, and flow cytometry. We showed that full-length mGluR6 localized to the ER and cell surface, whereas mGluR6 mutants with 15- and 20-amino acid deletions from the C terminus localized to the ER, but were deficient at the cell surface. We also demonstrated that the cell surface deficiency of mGluR6 mutants was rescued by introducing an alanine substitution at basic residues within the CTD. The surface-deficient mGluR6 mutant still did not localize to the cell surface and was retained in the ER when co-expressed with surface-expressible constructs, including full-length mGluR6, even though surface-deficient and surface-expressible constructs formed heteromeric complexes. The co-expression of the surface-deficient mGluR6 mutant reduced the surface levels of surface-expressible constructs. These results indicate that basic residues in the mGluR6 CTD served as ER retention signals. We suggest that exposed ER retention motifs in the aberrant assembly containing truncated or misfolded mGluR6 prevent these protein complexes from being transported to the cell surface.
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Affiliation(s)
- Atsushi Shimohata
- Department of Physiology, Nippon Medical School, Tokyo 113-8602, Japan
| | - Dilip Rai
- Department of Physiology, Nippon Medical School, Tokyo 113-8602, Japan
| | - Takumi Akagi
- Department of Physiology, Nippon Medical School, Tokyo 113-8602, Japan
| | - Sumiko Usui
- Department of Physiology, Nippon Medical School, Tokyo 113-8602, Japan
| | - Ikuo Ogiwara
- Department of Physiology, Nippon Medical School, Tokyo 113-8602, Japan.
| | - Makoto Kaneda
- Department of Physiology, Nippon Medical School, Tokyo 113-8602, Japan
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12
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Patil DN, Pantalone S, Cao Y, Laboute T, Novick SJ, Singh S, Savino S, Faravelli S, Magnani F, Griffin PR, Singh AK, Forneris F, Martemyanov KA. Structure of the photoreceptor synaptic assembly of the extracellular matrix protein pikachurin with the orphan receptor GPR179. Sci Signal 2023; 16:eadd9539. [PMID: 37490546 PMCID: PMC10561654 DOI: 10.1126/scisignal.add9539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 07/06/2023] [Indexed: 07/27/2023]
Abstract
Precise synapse formation is essential for normal functioning of the nervous system. Retinal photoreceptors establish selective contacts with bipolar cells, aligning the neurotransmitter release apparatus with postsynaptic signaling cascades. This involves transsynaptic assembly between the dystroglycan-dystrophin complex on the photoreceptor and the orphan receptor GPR179 on the bipolar cell, which is mediated by the extracellular matrix protein pikachurin (also known as EGFLAM). This complex plays a critical role in the synaptic organization of photoreceptors and signal transmission, and mutations affecting its components cause blinding disorders in humans. Here, we investigated the structural organization and molecular mechanisms by which pikachurin orchestrates transsynaptic assembly and solved structures of the human pikachurin domains by x-ray crystallography and of the GPR179-pikachurin complex by single-particle, cryo-electron microscopy. The structures reveal molecular recognition principles of pikachurin by the Cache domains of GPR179 and show how the interaction is involved in the transsynaptic alignment of the signaling machinery. Together, these data provide a structural basis for understanding the synaptic organization of photoreceptors and ocular pathology.
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Affiliation(s)
- Dipak N. Patil
- Department of Neuroscience, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL 33458, USA
| | - Serena Pantalone
- The Armenise-Harvard Laboratory of Structural Biology, Department of Biology and Biotechnology, University of Pavia, Via Ferrata, 9A, I-27100 Pavia, Italy
| | - Yan Cao
- Department of Neuroscience, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL 33458, USA
| | - Thibaut Laboute
- Department of Neuroscience, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL 33458, USA
| | - Scott J. Novick
- Department of Molecular Medicine, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL 33458, USA
| | - Shikha Singh
- Department of Biological Sciences, Columbia University New York, NY 10027, USA
| | - Simone Savino
- The Armenise-Harvard Laboratory of Structural Biology, Department of Biology and Biotechnology, University of Pavia, Via Ferrata, 9A, I-27100 Pavia, Italy
| | - Silvia Faravelli
- The Armenise-Harvard Laboratory of Structural Biology, Department of Biology and Biotechnology, University of Pavia, Via Ferrata, 9A, I-27100 Pavia, Italy
| | - Francesca Magnani
- The Armenise-Harvard Laboratory of Structural Biology, Department of Biology and Biotechnology, University of Pavia, Via Ferrata, 9A, I-27100 Pavia, Italy
| | - Patrick R. Griffin
- Department of Molecular Medicine, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL 33458, USA
| | - Appu K. Singh
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
- Mehta Family Centre for Engineering in Medicine, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Federico Forneris
- The Armenise-Harvard Laboratory of Structural Biology, Department of Biology and Biotechnology, University of Pavia, Via Ferrata, 9A, I-27100 Pavia, Italy
- Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | - Kirill A. Martemyanov
- Department of Neuroscience, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL 33458, USA
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13
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Keijser J, Sprekeler H. Cortical interneurons: fit for function and fit to function? Evidence from development and evolution. Front Neural Circuits 2023; 17:1172464. [PMID: 37215503 PMCID: PMC10192557 DOI: 10.3389/fncir.2023.1172464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 03/30/2023] [Indexed: 05/24/2023] Open
Abstract
Cortical inhibitory interneurons form a broad spectrum of subtypes. This diversity suggests a division of labor, in which each cell type supports a distinct function. In the present era of optimisation-based algorithms, it is tempting to speculate that these functions were the evolutionary or developmental driving force for the spectrum of interneurons we see in the mature mammalian brain. In this study, we evaluated this hypothesis using the two most common interneuron types, parvalbumin (PV) and somatostatin (SST) expressing cells, as examples. PV and SST interneurons control the activity in the cell bodies and the apical dendrites of excitatory pyramidal cells, respectively, due to a combination of anatomical and synaptic properties. But was this compartment-specific inhibition indeed the function for which PV and SST cells originally evolved? Does the compartmental structure of pyramidal cells shape the diversification of PV and SST interneurons over development? To address these questions, we reviewed and reanalyzed publicly available data on the development and evolution of PV and SST interneurons on one hand, and pyramidal cell morphology on the other. These data speak against the idea that the compartment structure of pyramidal cells drove the diversification into PV and SST interneurons. In particular, pyramidal cells mature late, while interneurons are likely committed to a particular fate (PV vs. SST) during early development. Moreover, comparative anatomy and single cell RNA-sequencing data indicate that PV and SST cells, but not the compartment structure of pyramidal cells, existed in the last common ancestor of mammals and reptiles. Specifically, turtle and songbird SST cells also express the Elfn1 and Cbln4 genes that are thought to play a role in compartment-specific inhibition in mammals. PV and SST cells therefore evolved and developed the properties that allow them to provide compartment-specific inhibition before there was selective pressure for this function. This suggest that interneuron diversity originally resulted from a different evolutionary driving force and was only later co-opted for the compartment-specific inhibition it seems to serve in mammals today. Future experiments could further test this idea using our computational reconstruction of ancestral Elfn1 protein sequences.
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Affiliation(s)
- Joram Keijser
- Modelling of Cognitive Processes, Technical University of Berlin, Berlin, Germany
- Einstein Center for Neurosciences, Charité University Medicine Berlin, Berlin, Germany
| | - Henning Sprekeler
- Modelling of Cognitive Processes, Technical University of Berlin, Berlin, Germany
- Bernstein Center for Computational Neuroscience Berlin, Humboldt University of Berlin, Berlin, Germany
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14
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Freitas GA, Niswender CM. GRM7 gene mutations and consequences for neurodevelopment. Pharmacol Biochem Behav 2023; 225:173546. [PMID: 37003303 PMCID: PMC10192299 DOI: 10.1016/j.pbb.2023.173546] [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: 02/24/2023] [Revised: 03/22/2023] [Accepted: 03/28/2023] [Indexed: 04/03/2023]
Abstract
The metabotropic glutamate receptor 7 (mGlu7), encoded by the GRM7 gene in humans, is a presynaptic, G protein-coupled glutamate receptor that is essential for modulating neurotransmission. Mutations in or reduced expression of GRM7 have been identified in different genetic neurodevelopmental disorders (NDDs), and rare biallelic missense variants have been proposed to underlie a subset of NDDs. Clinical GRM7 variants have been associated with a range of symptoms consistent with neurodevelopmental molecular features, including hypomyelination, brain atrophy and defects in axon outgrowth. Here, we review the newest findings regarding the cellular and molecular defects caused by GRM7 variants in NDD patients.
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Affiliation(s)
- Geanne A Freitas
- Department of Pharmacology and Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37212, United States of America
| | - Colleen M Niswender
- Department of Pharmacology and Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37212, United States of America; Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37212, United States of America; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37212, United States of America; Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37232, United States of America.
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15
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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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16
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Aldahabi M, Balint F, Holderith N, Lorincz A, Reva M, Nusser Z. Different priming states of synaptic vesicles underlie distinct release probabilities at hippocampal excitatory synapses. Neuron 2022; 110:4144-4161.e7. [PMID: 36261033 PMCID: PMC9796815 DOI: 10.1016/j.neuron.2022.09.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 07/28/2022] [Accepted: 09/27/2022] [Indexed: 12/12/2022]
Abstract
A stunning example of synaptic diversity is the postsynaptic target cell-type-dependent difference in synaptic efficacy in cortical networks. Here, we show that CA1 pyramidal cell (PC) to fast spiking interneuron (FSIN) connections have 10-fold larger release probability (Pv) than those on oriens lacunosum-moleculare (O-LM) interneurons. Freeze-fracture immunolabeling revealed that different nano-topologies and coupling distances between Ca2+ channels and release sites (RSs) are not responsible for the distinct Pv. Although [Ca2+] transients are 40% larger in FSINs innervating boutons, when [Ca2+] entry is matched in the two bouton populations, EPSCs in O-LM cells are still 7-fold smaller. However, application of a phorbol ester analog resulted in a ∼2.5-fold larger augmentation at PC - O-LM compared to PC - FSIN synapses, suggesting incomplete docking or priming of vesicles. Similar densities of docked vesicles rule out distinct RS occupancies and demonstrate that incompletely primed, but docked, vesicles limit the output of PC - O-LM synapses.
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Affiliation(s)
- Mohammad Aldahabi
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest 1083, Hungary,János Szentágothai School of Neurosciences, Semmelweis University, Budapest, Hungary
| | - Flora Balint
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest 1083, Hungary
| | - Noemi Holderith
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest 1083, Hungary
| | - Andrea Lorincz
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest 1083, Hungary
| | - Maria Reva
- Unit of Synapse and Circuit Dynamics, CNRS UMR 3571, Institute Pasteur, Paris, France
| | - Zoltan Nusser
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest 1083, Hungary,Corresponding author
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17
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Genetic Overlap Analysis Identifies a Shared Etiology between Migraine and Headache with Type 2 Diabetes. Genes (Basel) 2022; 13:genes13101845. [PMID: 36292730 PMCID: PMC9601333 DOI: 10.3390/genes13101845] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 09/26/2022] [Accepted: 10/11/2022] [Indexed: 11/17/2022] Open
Abstract
Migraine and headache frequently co-occur with type 2 diabetes (T2D), suggesting a shared aetiology between the two conditions. We used genome-wide association study (GWAS) data to investigate the genetic overlap and causal relationship between migraine and headache with T2D. Using linkage disequilibrium score regression (LDSC), we found a significant genetic correlation between migraine and T2D (rg = 0.06, p = 1.37 × 10−5) and between headache and T2D (rg = 0.07, p = 3.0 × 10−4). Using pairwise GWAS (GWAS-PW) analysis, we identified 11 pleiotropic regions between migraine and T2D and 5 pleiotropic regions between headache and T2D. Cross-trait SNP meta-analysis identified 23 novel SNP loci (Pmeta < 5 × 10−8) associated with migraine and T2D, and three novel SNP loci associated with headache and T2D. Cross-trait gene-based overlap analysis identified 33 genes significantly associated (Pgene-based < 3.85 × 10−6) with migraine and T2D, and 11 genes associated with headache and T2D, with 7 genes (EHMT2, SLC44A4, PLEKHA1, CFDP1, TMEM170A, CHST6, and BCAR1) common between them. There was also a significant overlap of genes nominally associated (Pgene-based < 0.05) with both migraine and T2D (Pbinomial-test = 2.83 × 10−46) and headache and T2D (Pbinomial-test = 4.08 × 10−29). Mendelian randomisation (MR) analyses did not provide consistent evidence for a causal relationship between migraine and T2D. However, we found headache was causally associated (inverse-variance weighted, ORIVW = 0.90, Pivw = 7 × 10−3) with T2D. Our findings robustly confirm the comorbidity of migraine and headache with T2D, with shared genetically controlled biological mechanisms contributing to their co-occurrence, and evidence for a causal relationship between headache and T2D.
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18
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Jaudon F, Thalhammer A, Zentilin L, Cingolani LA. CRISPR-mediated activation of autism gene Itgb3 restores cortical network excitability via mGluR5 signaling. MOLECULAR THERAPY - NUCLEIC ACIDS 2022; 29:462-480. [PMID: 36035754 PMCID: PMC9382421 DOI: 10.1016/j.omtn.2022.07.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 07/15/2022] [Indexed: 01/12/2023]
Abstract
Many mutations in autism spectrum disorder (ASD) affect a single allele, indicating a key role for gene dosage in ASD susceptibility. Recently, haplo-insufficiency of ITGB3, the gene encoding the extracellular matrix receptor β3 integrin, was associated with ASD. Accordingly, Itgb3 knockout (KO) mice exhibit autism-like phenotypes. The pathophysiological mechanisms of Itgb3 remain, however, unknown, and the potential of targeting this gene for developing ASD therapies uninvestigated. By combining molecular, biochemical, imaging, and pharmacological analyses, we establish that Itgb3 haplo-insufficiency impairs cortical network excitability by promoting extra-synaptic over synaptic signaling of the metabotropic glutamate receptor mGluR5, which is similarly dysregulated in fragile X syndrome, the most frequent monogenic form of ASD. To assess the therapeutic potential of regulating Itgb3 gene dosage, we implemented CRISPR activation and compared its efficacy with that of a pharmacological rescue strategy for fragile X syndrome. Correction of neuronal Itgb3 haplo-insufficiency by CRISPR activation rebalanced network excitability as effectively as blockade of mGluR5 with the selective antagonist MPEP. Our findings reveal an unexpected functional interaction between two ASD genes, thereby validating the pathogenicity of ITGB3 haplo-insufficiency. Further, they pave the way for exploiting CRISPR activation as gene therapy for normalizing gene dosage and network excitability in ASD.
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Affiliation(s)
- Fanny Jaudon
- Center for Synaptic Neuroscience and Technology (NSYN), Fondazione Istituto Italiano di Tecnologia (IIT), 16132 Genoa, Italy
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
| | - Agnes Thalhammer
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
- IRCCS Ospedale Policlinico San Martino, 16132 Genoa, Italy
| | - Lorena Zentilin
- AAV Vector Unit, International Centre for Genetic Engineering and Biotechnology (ICGEB), 34149 Trieste, Italy
| | - Lorenzo A. Cingolani
- Center for Synaptic Neuroscience and Technology (NSYN), Fondazione Istituto Italiano di Tecnologia (IIT), 16132 Genoa, Italy
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
- Corresponding author Lorenzo A. Cingolani, Department of Life Sciences, University of Trieste, 34127 Trieste, Italy.
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19
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Ichise M, Sakoori K, Katayama KI, Morimura N, Yamada K, Ozawa H, Matsunaga H, Hatayama M, Aruga J. Leucine-Rich Repeats and Transmembrane Domain 2 Controls Protein Sorting in the Striatal Projection System and Its Deficiency Causes Disturbances in Motor Responses and Monoamine Dynamics. Front Mol Neurosci 2022; 15:856315. [PMID: 35615067 PMCID: PMC9126195 DOI: 10.3389/fnmol.2022.856315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 03/07/2022] [Indexed: 11/13/2022] Open
Abstract
The striatum is involved in action selection, and its disturbance can cause movement disorders. Here, we show that leucine-rich repeats and transmembrane domain 2 (Lrtm2) controls protein sorting in striatal projection systems, and its deficiency causes disturbances in monoamine dynamics and behavior. The Lrtm2 protein was broadly detected in the brain, but it was enhanced in the olfactory bulb and dorsal striatum. Immunostaining revealed a strong signal in striatal projection output, including GABAergic presynaptic boutons of the SNr. In subcellular fractionation, Lrtm2 was abundantly recovered in the synaptic plasma membrane fraction, synaptic vesicle fraction, and microsome fraction. Lrtm2 KO mice exhibited altered motor responses in both voluntary explorations and forced exercise. Dopamine metabolite content was decreased in the dorsal striatum and hypothalamus, and serotonin turnover increased in the dorsal striatum. The prefrontal cortex showed age-dependent changes in dopamine metabolites. The distribution of glutamate decarboxylase 67 (GAD67) protein and gamma-aminobutyric acid receptor type B receptor 1 (GABABR1) protein was altered in the dorsal striatum. In cultured neurons, wild-type Lrtm2 protein enhanced axon trafficking of GAD67-GFP and GABABR1-GFP whereas such activity was defective in sorting signal-abolished Lrtm2 mutant proteins. The topical expression of hemagglutinin-epitope-tag (HA)-Lrtm2 and a protein sorting signal abolished HA-Lrtm2 mutant differentially affected GABABR1 protein distribution in the dorsal striatum. These results suggest that Lrtm2 is an essential component of striatal projection neurons, contributing to a better understanding of striatal pathophysiology.
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Affiliation(s)
- Misato Ichise
- Department of Medical Pharmacology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
- Department of Neuropsychiatry, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Kazuto Sakoori
- Laboratory for Behavioral and Developmental Disorders, RIKEN Brain Science Institute (BSI), Wako-shi, Japan
| | - Kei-ichi Katayama
- Laboratory for Behavioral and Developmental Disorders, RIKEN Brain Science Institute (BSI), Wako-shi, Japan
| | - Naoko Morimura
- Laboratory for Behavioral and Developmental Disorders, RIKEN Brain Science Institute (BSI), Wako-shi, Japan
| | - Kazuyuki Yamada
- Support Unit for Animal Experiments, RIKEN Brain Science Institute (BSI), Wako-shi, Japan
| | - Hiroki Ozawa
- Department of Neuropsychiatry, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Hayato Matsunaga
- Department of Medical Pharmacology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Minoru Hatayama
- Department of Medical Pharmacology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
- Laboratory for Behavioral and Developmental Disorders, RIKEN Brain Science Institute (BSI), Wako-shi, Japan
| | - Jun Aruga
- Department of Medical Pharmacology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
- Laboratory for Behavioral and Developmental Disorders, RIKEN Brain Science Institute (BSI), Wako-shi, Japan
- *Correspondence: Jun Aruga,
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20
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Bodzęta A, Berger F, MacGillavry HD. Subsynaptic mobility of presynaptic mGluR types is differentially regulated by intra- and extracellular interactions. Mol Biol Cell 2022; 33:ar66. [PMID: 35511883 PMCID: PMC9635276 DOI: 10.1091/mbc.e21-10-0484] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Presynaptic metabotropic glutamate receptors (mGluRs) are essential for the control of synaptic transmission. However, how the subsynaptic dynamics of these receptors is controlled and contributes to synaptic signaling remain poorly understood quantitatively. Particularly, since the affinity of individual mGluR subtypes for glutamate differs considerably, the activation of mGluR subtypes critically depends on their precise subsynaptic distribution. Here, using superresolution microscopy and single-molecule tracking, we unravel novel molecular mechanisms that control the nanoscale distribution and mobility of presynaptic mGluRs in hippocampal neurons. We demonstrate that the high-affinity group II receptor mGluR2 localizes diffusely along the axon, and is highly mobile, while the low-affinity group III receptor mGluR7 is stably anchored at the active zone. We demonstrate that intracellular interactions modulate surface diffusion of mGluR2, while immobilization of mGluR7 at the active zone relies on its extracellular domain. Receptor activation or increases in synaptic activity do not alter the surface mobility of presynaptic mGluRs. Finally, computational modeling of presynaptic mGluR activity revealed that this particular nanoscale arrangement directly impacts their ability to modulate neurotransmitter release. Altogether, this study demonstrates that distinct mechanisms control surface mobility of presynaptic mGluRs to contribute differentially to glutamatergic synaptic transmission.
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Affiliation(s)
- Anna Bodzęta
- Division of Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH, The Netherlands
| | - Florian Berger
- Division of Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH, The Netherlands
| | - Harold D MacGillavry
- Division of Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH, The Netherlands
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21
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Creasy CA, Meng YJ, Forget MA, Karpinets T, Tomczak K, Stewart C, Torres-Cabala CA, Pilon-Thomas S, Sarnaik AA, Mulé JJ, Garraway L, Bustos M, Zhang J, Patel SP, Diab A, Glitza IC, Yee C, Tawbi H, Wong MK, McQuade J, Hoon DSB, Davies MA, Hwu P, Amaria RN, Haymaker C, Beroukhim R, Bernatchez C. Genomic Correlates of Outcome in Tumor-Infiltrating Lymphocyte Therapy for Metastatic Melanoma. Clin Cancer Res 2022; 28:1911-1924. [PMID: 35190823 DOI: 10.1158/1078-0432.ccr-21-1060] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 07/01/2021] [Accepted: 02/16/2022] [Indexed: 11/16/2022]
Abstract
PURPOSE Adoptive cell therapy (ACT) of tumor-infiltrating lymphocytes (TIL) historically yields a 40%-50% response rate in metastatic melanoma. However, the determinants of outcome are largely unknown. EXPERIMENTAL DESIGN We investigated tumor-based genomic correlates of overall survival (OS), progression-free survival (PFS), and response to therapy by interrogating tumor samples initially collected to generate TIL infusion products. RESULTS Whole-exome sequencing (WES) data from 64 samples indicated a positive correlation between neoantigen load and OS, but not PFS or response to therapy. RNA sequencing analysis of 34 samples showed that expression of PDE1C, RTKN2, and NGFR was enriched in responders who had improved PFS and OS. In contrast, the expression of ELFN1 was enriched in patients with unfavorable response, poor PFS and OS, whereas enhanced methylation of ELFN1 was observed in patients with favorable outcomes. Expression of ELFN1, NGFR, and PDE1C was mainly found in cancer-associated fibroblasts and endothelial cells in tumor tissues across different cancer types in publicly available single-cell RNA sequencing datasets, suggesting a role for elements of the tumor microenvironment in defining the outcome of TIL therapy. CONCLUSIONS Our findings suggest that transcriptional features of melanomas correlate with outcomes after TIL therapy and may provide candidates to guide patient selection.
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Affiliation(s)
- Caitlin A Creasy
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center (MDACC), Houston, Texas
| | - Yuzhong Jeff Meng
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts.,Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts.,Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - Marie-Andrée Forget
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center (MDACC), Houston, Texas
| | - Tatiana Karpinets
- Department of Genomic Medicine, The University of Texas MDACC, Houston, Texas
| | - Katarzyna Tomczak
- Department of Translational Molecular Pathology, The University of Texas MDACC, Houston, Texas
| | - Chip Stewart
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts
| | | | - Shari Pilon-Thomas
- Department of Immunology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida.,Department of Cutaneous Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - Amod A Sarnaik
- Department of Cutaneous Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - James J Mulé
- Department of Immunology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - Levi Garraway
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts.,Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts.,Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - Matias Bustos
- Department of Translational Molecular Medicine, Saint John's Cancer Institute, Saint John's Health Center, Santa Monica, California
| | - Jianhua Zhang
- Department of Genomic Medicine, The University of Texas MDACC, Houston, Texas
| | - Sapna P Patel
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center (MDACC), Houston, Texas
| | - Adi Diab
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center (MDACC), Houston, Texas
| | - Isabella C Glitza
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center (MDACC), Houston, Texas
| | - Cassian Yee
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center (MDACC), Houston, Texas
| | - Hussein Tawbi
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center (MDACC), Houston, Texas
| | - Michael K Wong
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center (MDACC), Houston, Texas
| | - Jennifer McQuade
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center (MDACC), Houston, Texas
| | - Dave S B Hoon
- Department of Translational Molecular Medicine, Saint John's Cancer Institute, Saint John's Health Center, Santa Monica, California
| | - Michael A Davies
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center (MDACC), Houston, Texas
| | - Patrick Hwu
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center (MDACC), Houston, Texas
| | - Rodabe N Amaria
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center (MDACC), Houston, Texas
| | - Cara Haymaker
- Department of Translational Molecular Pathology, The University of Texas MDACC, Houston, Texas
| | - Rameen Beroukhim
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts.,Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts.,Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - Chantale Bernatchez
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center (MDACC), Houston, Texas.,Department of Translational Molecular Pathology, The University of Texas MDACC, Houston, Texas
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22
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Holderith N, Aldahabi M, Nusser Z. Selective Enrichment of Munc13-2 in Presynaptic Active Zones of Hippocampal Pyramidal Cells That Innervate mGluR1α Expressing Interneurons. Front Synaptic Neurosci 2022; 13:773209. [PMID: 35221979 PMCID: PMC8866005 DOI: 10.3389/fnsyn.2021.773209] [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: 09/09/2021] [Accepted: 12/27/2021] [Indexed: 11/13/2022] Open
Abstract
Selective distribution of proteins in presynaptic active zones (AZs) is a prerequisite for generating postsynaptic target cell type-specific differences in presynaptic vesicle release probability (Pv) and short-term plasticity, a characteristic feature of cortical pyramidal cells (PCs). In the hippocampus of rodents, somatostatin and mGluR1α expressing interneurons (mGluR1α+ INs) receive small, facilitating excitatory postsynaptic currents (EPSCs) from PCs and express Elfn1 that trans-synaptically recruits mGluR7 into the presynaptic AZ of PC axons. Here we show that Elfn1 also has a role in the selective recruitment of Munc13-2, a synaptic vesicle priming and docking protein, to PC AZs that innervate mGluR1α+ INs. In Elfn1 knock-out mice, unitary EPSCs (uEPSCs) in mGluR1α+ INs have threefold larger amplitudes with less pronounced short-term facilitation, which might be the consequence of the loss of either mGluR7 or Munc13-2 or both. Conditional genetic deletion of Munc13-2 from CA1 PCs results in the loss of Munc13-2, but not mGluR7 from the AZs, and has no effect on the amplitude of uEPSCs and leaves the characteristic short-term facilitation intact at PC to mGluR1α+ IN connection. Our results demonstrate that Munc13-1 alone is capable of imposing low Pv at PC to mGluR1α+ IN synapses and Munc13-2 has yet an unknown role in this synapse.
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Affiliation(s)
- Noemi Holderith
- Institute of Experimental Medicine, Eotvos Lorand Research Network, Budapest, Hungary
| | - Mohammad Aldahabi
- Institute of Experimental Medicine, Eotvos Lorand Research Network, Budapest, Hungary
- János Szentágothai School of Neurosciences, Semmelweis University, Budapest, Hungary
| | - Zoltan Nusser
- Institute of Experimental Medicine, Eotvos Lorand Research Network, Budapest, Hungary
- *Correspondence: Zoltan Nusser,
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23
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Exome Sequencing Reveals Novel Variants and Expands the Genetic Landscape for Congenital Microcephaly. Genes (Basel) 2021; 12:genes12122014. [PMID: 34946966 PMCID: PMC8700965 DOI: 10.3390/genes12122014] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/12/2021] [Accepted: 12/15/2021] [Indexed: 11/23/2022] Open
Abstract
Congenital microcephaly causes smaller than average head circumference relative to age, sex and ethnicity and is most usually associated with a variety of neurodevelopmental disorders. The underlying etiology is highly heterogeneous and can be either environmental or genetic. Disruption of any one of multiple biological processes, such as those underlying neurogenesis, cell cycle and division, DNA repair or transcription regulation, can result in microcephaly. This etiological heterogeneity manifests in a clinical variability and presents a major diagnostic and therapeutic challenge, leaving an unacceptably large proportion of over half of microcephaly patients without molecular diagnosis. To elucidate the clinical and genetic landscapes of congenital microcephaly, we sequenced the exomes of 191 clinically diagnosed patients with microcephaly as one of the features. We established a molecular basis for microcephaly in 71 patients (37%), and detected novel variants in five high confidence candidate genes previously unassociated with this condition. We report a large number of patients with mutations in tubulin-related genes in our cohort as well as higher incidence of pathogenic mutations in MCPH genes. Our study expands the phenotypic and genetic landscape of microcephaly, facilitating differential clinical diagnoses for disorders associated with most commonly disrupted genes in our cohort.
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24
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Membrane trafficking and positioning of mGluRs at presynaptic and postsynaptic sites of excitatory synapses. Neuropharmacology 2021; 200:108799. [PMID: 34592242 DOI: 10.1016/j.neuropharm.2021.108799] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 08/31/2021] [Accepted: 09/17/2021] [Indexed: 01/21/2023]
Abstract
The plethora of functions of glutamate in the brain are mediated by the complementary actions of ionotropic and metabotropic glutamate receptors (mGluRs). The ionotropic glutamate receptors carry most of the fast excitatory transmission, while mGluRs modulate transmission on longer timescales by triggering multiple intracellular signaling pathways. As such, mGluRs mediate critical aspects of synaptic transmission and plasticity. Interestingly, at synapses, mGluRs operate at both sides of the cleft, and thus bidirectionally exert the effects of glutamate. At postsynaptic sites, group I mGluRs act to modulate excitability and plasticity. At presynaptic sites, group II and III mGluRs act as auto-receptors, modulating release properties in an activity-dependent manner. Thus, synaptic mGluRs are essential signal integrators that functionally couple presynaptic and postsynaptic mechanisms of transmission and plasticity. Understanding how these receptors reach the membrane and are positioned relative to the presynaptic glutamate release site are therefore important aspects of synapse biology. In this review, we will discuss the currently known mechanisms underlying the trafficking and positioning of mGluRs at and around synapses, and how these mechanisms contribute to synaptic functioning. We will highlight outstanding questions and present an outlook on how recent technological developments will move this exciting research field forward.
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25
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Agosto MA, Adeosun AAR, Kumar N, Wensel TG. The mGluR6 ligand-binding domain, but not the C-terminal domain, is required for synaptic localization in retinal ON-bipolar cells. J Biol Chem 2021; 297:101418. [PMID: 34793838 PMCID: PMC8671642 DOI: 10.1016/j.jbc.2021.101418] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/03/2021] [Accepted: 11/08/2021] [Indexed: 11/26/2022] Open
Abstract
Signals from retinal photoreceptors are processed in two parallel channels—the ON channel responds to light increments, while the OFF channel responds to light decrements. The ON pathway is mediated by ON type bipolar cells (BCs), which receive glutamatergic synaptic input from photoreceptors via a G-protein-coupled receptor signaling cascade. The metabotropic glutamate receptor mGluR6 is located at the dendritic tips of all ON-BCs and is required for synaptic transmission. Thus, it is critically important for delivery of information from photoreceptors into the ON pathway. In addition to detecting glutamate, mGluR6 participates in interactions with other postsynaptic proteins, as well as trans-synaptic interactions with presynaptic ELFN proteins. Mechanisms of mGluR6 synaptic targeting and functional interaction with other synaptic proteins are unknown. Here, we show that multiple regions in the mGluR6 ligand-binding domain are necessary for both synaptic localization in BCs and ELFN1 binding in vitro. However, these regions were not required for plasma membrane localization in heterologous cells, indicating that secretory trafficking and synaptic localization are controlled by different mechanisms. In contrast, the mGluR6 C-terminus was dispensable for synaptic localization. In mGluR6 null mice, localization of the postsynaptic channel protein TRPM1 was compromised. Introducing WT mGluR6 rescued TRPM1 localization, while a C-terminal deletion mutant had significantly reduced rescue ability. We propose a model in which trans-synaptic ELFN1 binding is necessary for mGluR6 postsynaptic localization, whereas the C-terminus has a role in mediating TRPM1 trafficking. These findings reveal different sequence determinants of the multifunctional roles of mGluR6 in ON-BCs.
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Affiliation(s)
- Melina A Agosto
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston TX, USA.
| | - Abiodun Adefola R Adeosun
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston TX, USA; Pharmacology and Chemical Biology Graduate Program, Baylor College of Medicine, Houston TX, USA
| | - Nitin Kumar
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston TX, USA
| | - Theodore G Wensel
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston TX, USA; Pharmacology and Chemical Biology Graduate Program, Baylor College of Medicine, Houston TX, USA
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26
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Liu Y, Wang Y, Yang J, Xu T, Tan C, Zhang P, Liu Q, Chen Y. G-alpha interacting protein interacting protein, C terminus 1 regulates epileptogenesis by increasing the expression of metabotropic glutamate receptor 7. CNS Neurosci Ther 2021; 28:126-138. [PMID: 34676980 PMCID: PMC8673704 DOI: 10.1111/cns.13746] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 10/04/2021] [Accepted: 10/05/2021] [Indexed: 12/31/2022] Open
Abstract
Aims It has been reported that the G‐alpha interacting protein (GAIP) interacting protein, C terminus 1 (GIPC1/GIPC) engages in vesicular trafficking, receptor transport and expression, and endocytosis. However, its role in epilepsy is unclear. Therefore, in this study, we aimed to explore the role of GIPC1 in epilepsy and its possible underlying mechanism. Methods The expression patterns of GIPC1 in patients with temporal lobe epilepsy (TLE) and in mice with kainic acid (KA)‐induced epilepsy were detected. Behavioral video monitoring and hippocampal local field potential (LFP) recordings were carried out to determine the role of GIPC1 in epileptogenesis after overexpression of GIPC1. Coimmunoprecipitation (Co‐IP) assay and high‐resolution immunofluorescence staining were conducted to investigate the relationship between GIPC1 and metabotropic glutamate receptor 7 (mGluR7). In addition, the expression of mGluR7 after overexpression of GIPC1 was measured, and behavioral video monitoring and LFP recordings after antagonism of mGluR7 were performed to explore the possible mechanism mediated by GIPC1. Results GIPC1 was downregulated in the brain tissues of patients with TLE and mice with KA‐induced epilepsy. After overexpression of GIPC1, prolonged latency period, decreased epileptic seizures and reduced seizure severity in behavioral analyses, and fewer and shorter abnormal brain discharges in LFP recordings of KA‐induced epileptic mice were observed. The result of the Co‐IP assay showed the interaction between GIPC1 and mGluR7, and the high‐resolution immunofluorescence staining also showed the colocalization of these two proteins. Additionally, along with GIPC1 overexpression, the total and cell membrane expression levels of mGluR7 were also increased. And after antagonism of mGluR7, increased epileptic seizures and aggravated seizure severity in behavioral analyses and more and longer abnormal brain discharges in LFP recordings were observed. Conclusion GIPC1 regulates epileptogenesis by interacting with mGluR7 and increasing its expression.
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Affiliation(s)
- Yong Liu
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chonqing, China
| | - You Wang
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chonqing, China
| | - Juan Yang
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chonqing, China.,Department of Neurology, The Affiliated Hospital of Zunyi Medical University, Guizhou, China
| | - Tao Xu
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chonqing, China
| | - Changhong Tan
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chonqing, China
| | - Peng Zhang
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chonqing, China
| | - Qiankun Liu
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chonqing, China
| | - Yangmei Chen
- Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chonqing, China
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27
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Gutman-Wei AY, Brown SP. Mechanisms Underlying Target Selectivity for Cell Types and Subcellular Domains in Developing Neocortical Circuits. Front Neural Circuits 2021; 15:728832. [PMID: 34630048 PMCID: PMC8497978 DOI: 10.3389/fncir.2021.728832] [Citation(s) in RCA: 3] [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: 06/22/2021] [Accepted: 08/25/2021] [Indexed: 11/25/2022] Open
Abstract
The cerebral cortex contains numerous neuronal cell types, distinguished by their molecular identity as well as their electrophysiological and morphological properties. Cortical function is reliant on stereotyped patterns of synaptic connectivity and synaptic function among these neuron types, but how these patterns are established during development remains poorly understood. Selective targeting not only of different cell types but also of distinct postsynaptic neuronal domains occurs in many brain circuits and is directed by multiple mechanisms. These mechanisms include the regulation of axonal and dendritic guidance and fine-scale morphogenesis of pre- and postsynaptic processes, lineage relationships, activity dependent mechanisms and intercellular molecular determinants such as transmembrane and secreted molecules, many of which have also been implicated in neurodevelopmental disorders. However, many studies of synaptic targeting have focused on circuits in which neuronal processes target different lamina, such that cell-type-biased connectivity may be confounded with mechanisms of laminar specificity. In the cerebral cortex, each cortical layer contains cell bodies and processes from intermingled neuronal cell types, an arrangement that presents a challenge for the development of target-selective synapse formation. Here, we address progress and future directions in the study of cell-type-biased synaptic targeting in the cerebral cortex. We highlight challenges to identifying developmental mechanisms generating stereotyped patterns of intracortical connectivity, recent developments in uncovering the determinants of synaptic target selection during cortical synapse formation, and current gaps in the understanding of cortical synapse specificity.
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Affiliation(s)
- Alan Y. Gutman-Wei
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Solange P. Brown
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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28
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Dursun A, Yalnizoglu D, Yilmaz DY, Oguz KK, Gülbakan B, Koşukcu C, Akar HT, Kahraman AB, Acar NV, Günbey C, Yildiz Y, Ozgul RK. Biallelic mutations in ELFN1 gene associated with developmental and epileptic encephalopathy and joint laxity. Eur J Med Genet 2021; 64:104340. [PMID: 34509675 DOI: 10.1016/j.ejmg.2021.104340] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 07/06/2021] [Accepted: 09/05/2021] [Indexed: 11/26/2022]
Abstract
ELFN1, a transmembrane leucine rich repeat protein, is involved in signal transduction in both neural cells and ROD ON-bipolar synaptogenesis. We present three siblings with developmental and epileptic encephalopathy and co-morbidities due to ELFN1 gene mutation; this is the first report in literature defining the human phenotype of ELFN1 gene mutation. Clinical, electrophysiological, and radiological findings along with comprehensive genetic studies of the patients and their family members are presented. Developmental and epileptic encephalopathy, autistic features, pyramidal signs, joint laxity, and dysmorphic features are the characteristic findings of this new clinical entity, involving mainly nervous system and possibly connective tissue. Whole exome sequence analysis followed by Sanger sequencing in all family members revealed disease-causing 8 bp frameshift mutation depicted as NM_001128636.2: c.42_49delGGCCGCCA; p. (Ala15Profs*241) in ELFN1. The variant, located in the signal peptide domain in the ELFN1 gene, was found to be homozygous in three patients, and heterozygous in the parents and three healthy siblings. Segregation analysis in family members together with pathogenicity assessment tools strongly supported the damaging effect of the frameshift variant on the function of the ELFN1 protein. Mutations in ELFN1 gene may be considered in patients with neonatal and infantile-onset epileptic encephalopathy before the full clinical picture is apparent.
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Affiliation(s)
- Ali Dursun
- Hacettepe University Faculty of Medicine, Department of Pediatric Metabolism, Ankara, Turkey.
| | - Dilek Yalnizoglu
- Hacettepe University Faculty of Medicine, Department of Pediatric Neurology, Ankara, Turkey
| | | | - Kader Karli Oguz
- Hacettepe University Faculty of Medicine, Department of Radiology, Ankara, Turkey
| | - Basri Gülbakan
- Hacettepe University Institute of Child Health, Ankara, Turkey
| | - Can Koşukcu
- Hacettepe University Institute of Health Sciences, Department of Bioinformatics, Ankara, Turkey
| | - Halil Tuna Akar
- Hacettepe University Faculty of Medicine, Department of Pediatric Metabolism, Ankara, Turkey
| | - Ayça Burcu Kahraman
- Hacettepe University Faculty of Medicine, Department of Pediatric Metabolism, Ankara, Turkey
| | | | - Ceren Günbey
- Hacettepe University Faculty of Medicine, Department of Pediatric Neurology, Ankara, Turkey
| | - Yilmaz Yildiz
- Hacettepe University Faculty of Medicine, Department of Pediatric Metabolism, Ankara, Turkey
| | - R Koksal Ozgul
- Hacettepe University Institute of Child Health, Ankara, Turkey
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29
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Rasheed M, Khan V, Harripaul R, Siddiqui M, Malik MA, Ullah Z, Zahid M, Vincent JB, Ansar M. Exome sequencing identifies novel and known mutations in families with intellectual disability. BMC Med Genomics 2021; 14:211. [PMID: 34452636 PMCID: PMC8399827 DOI: 10.1186/s12920-021-01066-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 08/25/2021] [Indexed: 12/29/2022] Open
Abstract
Background Intellectual disability (ID) is a phenotypically and genetically heterogeneous disorder. Methods In this study, genome wide SNP microarray and whole exome sequencing are used for the variant identification in eight Pakistani families with ID. Beside ID, most of the affected individuals had speech delay, facial dysmorphism and impaired cognitive abilities. Repetitive behavior was observed in MRID143, while seizures were reported in affected individuals belonging to MRID137 and MRID175. Results In two families (MRID137b and MRID175), we identified variants in the genes CCS and ELFN1, which have not previously been reported to cause ID. In four families, variants were identified in ARX, C5orf42, GNE and METTL4. A copy number variation (CNV) was identified in IL1RAPL1 gene in MRID165. Conclusion These findings expand the existing knowledge of variants and genes implicated in autosomal recessive and X linked ID. Supplementary Information The online version contains supplementary material available at 10.1186/s12920-021-01066-y.
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Affiliation(s)
- Memoona Rasheed
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-I-Azam University, Islamabad, 45320, Pakistan
| | - Valeed Khan
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-I-Azam University, Islamabad, 45320, Pakistan
| | - Ricardo Harripaul
- Molecular Neuropsychiatry and Development (MiND) Lab, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, M5T 1R8, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Maimoona Siddiqui
- Division of Neurology, Shifa College of Medicine, H-8/1, Islamabad, Pakistan
| | - Madiha Amin Malik
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-I-Azam University, Islamabad, 45320, Pakistan
| | - Zahid Ullah
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-I-Azam University, Islamabad, 45320, Pakistan
| | - Muhammad Zahid
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-I-Azam University, Islamabad, 45320, Pakistan
| | - John B Vincent
- Molecular Neuropsychiatry and Development (MiND) Lab, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, M5T 1R8, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, M5S 1A8, Canada.,Department of Psychiatry, University of Toronto, Toronto, ON, M5T 1R8, Canada
| | - Muhammad Ansar
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-I-Azam University, Islamabad, 45320, Pakistan.
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30
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Matsunaga H, Aruga J. Trans-Synaptic Regulation of Metabotropic Glutamate Receptors by Elfn Proteins in Health and Disease. Front Neural Circuits 2021; 15:634875. [PMID: 33790745 PMCID: PMC8005653 DOI: 10.3389/fncir.2021.634875] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Accepted: 02/08/2021] [Indexed: 12/20/2022] Open
Abstract
Trans-regulation of G protein-coupled receptors (GPCRs) by leucine-rich repeat (LRR) transmembrane proteins has emerged as a novel type of synaptic molecular interaction in the last decade. Several studies on LRR–GPCR interactions have revealed their critical role in synapse formation and in establishing synaptic properties. Among them, LRR–GPCR interactions between extracellular LRR fibronectin domain-containing family proteins (Elfn1 and Elfn2) and metabotropic glutamate receptors (mGluRs) are particularly interesting as they can affect a broad range of synapses through the modulation of signaling by glutamate, the principal excitatory transmitter in the mammalian central nervous system (CNS). Elfn–mGluR interactions have been investigated in hippocampal, cortical, and retinal synapses. Postsynaptic Elfn1 in the hippocampus and cerebral cortex mediates the tonic regulation of excitatory input onto somatostatin-positive interneurons (INs) through recruitment of presynaptic mGluR7. In the retina, presynaptic Elfn1 binds to mGluR6 and is necessary for synapse formation between rod photoreceptor cells and rod-bipolar cells. The repertoire of binding partners for Elfn1 and Elfn2 includes all group III mGluRs (mGluR4, mGluR6, mGluR7, and mGluR8), and both Elfn1 and Elfn2 can alter mGluR-mediated signaling through trans-interaction. Importantly, both preclinical and clinical studies have provided support for the involvement of the Elfn1–mGluR7 interaction in attention-deficit hyperactivity disorder (ADHD), post-traumatic stress disorder (PTSD), and epilepsy. In fact, Elfn1–mGluR7-associated disorders may reflect the altered function of somatostatin-positive interneuron inhibitory neural circuits, the mesolimbic and nigrostriatal dopaminergic pathway, and habenular circuits, highlighting the need for further investigation into this interaction.
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Affiliation(s)
- Hayato Matsunaga
- Department of Medical Pharmacology, Nagasaki University Institute of Biomedical Sciences, Nagasaki, Japan
| | - Jun Aruga
- Department of Medical Pharmacology, Nagasaki University Institute of Biomedical Sciences, Nagasaki, Japan
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31
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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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32
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Sun Y, Sun X. Exploring the interstitial system in the brain: the last mile of drug delivery. Rev Neurosci 2021; 32:363-377. [PMID: 33550781 DOI: 10.1515/revneuro-2020-0057] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Accepted: 12/08/2020] [Indexed: 11/15/2022]
Abstract
Brain interstitial system (ISS) is a nanoscale network of continuously connected tubes and sheets surrounding each neural cell in the central nervous system. ISS usually accounts for ∼20% of the brain volume, far more than the cerebral blood vessels, which account for 3%. The neuronal function, signaling pathways, and drug delivery are all closely related to the microenvironment provided by ISS. The objective of this paper is to give the readers a clear outline of detection, anatomy, function, and applications of ISS. This review describes the techniques propelling the exploration for ISS in chronological order, physiological function and pathological dysfunction of ISS, and strategies for drug delivery based on ISS. Biophysical features are the focus of ISS research, in which the diffusion characteristics have dominated. The various techniques that explore ISS take advantage of this feature. ISS provides an essential microenvironment for the health of cells and brain homeostasis, which plays an important functional role in brain health and disease. Direct intracranial administration allows the diffusion of drugs directly through ISS to successfully bypass the blood-brain barrier that prevents most drugs from reaching the brain. With the deepening of understanding of the brain ISS, the new research model that takes into account brain cells, cerebral vessels, and ISS will provide a new perspective and direction for understanding, utilizing, and protecting the brain.
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Affiliation(s)
- Yi Sun
- National Key Research Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100191, P. R. China.,Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University, Beijing 100191, P. R. China
| | - Xinping Sun
- Clinical Laboratory, Peking University International Hospital, Beijing 102206, P. R. China
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33
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Kim HY, Um JW, Ko J. Proper synaptic adhesion signaling in the control of neural circuit architecture and brain function. Prog Neurobiol 2021; 200:101983. [PMID: 33422662 DOI: 10.1016/j.pneurobio.2020.101983] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 11/23/2020] [Accepted: 12/22/2020] [Indexed: 12/17/2022]
Abstract
Trans-synaptic cell-adhesion molecules are critical for governing various stages of synapse development and specifying neural circuit properties via the formation of multifarious signaling pathways. Recent studies have pinpointed the putative roles of trans-synaptic cell-adhesion molecules in mediating various cognitive functions. Here, we review the literature on the roles of a diverse group of central synaptic organizers, including neurexins (Nrxns), leukocyte common antigen-related receptor protein tyrosine phosphatases (LAR-RPTPs), and their associated binding proteins, in regulating properties of specific type of synapses and neural circuits. In addition, we highlight the findings that aberrant synaptic adhesion signaling leads to alterations in the structures, transmission, and plasticity of specific synapses across diverse brain areas. These results seem to suggest that proper trans-synaptic signaling pathways by Nrxns, LAR-RPTPs, and their interacting network is likely to constitute central molecular complexes that form the basis for cognitive functions, and that these complexes are heterogeneously and complexly disrupted in many neuropsychiatric and neurodevelopmental disorders.
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Affiliation(s)
- Hee Young Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, South Korea
| | - Ji Won Um
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, South Korea; Core Protein Resources Center, DGIST, Daegu, 42988, South Korea.
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, South Korea.
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Jang S, Yang E, Kim D, Kim H, Kim E. Clmp Regulates AMPA and Kainate Receptor Responses in the Neonatal Hippocampal CA3 and Kainate Seizure Susceptibility in Mice. Front Synaptic Neurosci 2021; 12:567075. [PMID: 33408624 PMCID: PMC7779639 DOI: 10.3389/fnsyn.2020.567075] [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: 06/11/2020] [Accepted: 12/02/2020] [Indexed: 12/05/2022] Open
Abstract
Synaptic adhesion molecules regulate synapse development through trans-synaptic adhesion and assembly of diverse synaptic proteins. Many synaptic adhesion molecules positively regulate synapse development; some, however, exert negative regulation, although such cases are relatively rare. In addition, synaptic adhesion molecules regulate the amplitude of post-synaptic receptor responses, but whether adhesion molecules can regulate the kinetic properties of post-synaptic receptors remains unclear. Here we report that Clmp, a homophilic adhesion molecule of the Ig domain superfamily that is abundantly expressed in the brain, reaches peak expression at a neonatal stage (week 1) and associates with subunits of AMPA receptors (AMPARs) and kainate receptors (KARs). Clmp deletion in mice increased the frequency and amplitude of AMPAR-mediated miniature excitatory post-synaptic currents (mEPSCs) and the frequency, amplitude, and decay time constant of KAR-mediated mEPSCs in hippocampal CA3 neurons. Clmp deletion had minimal impacts on evoked excitatory synaptic currents at mossy fiber-CA3 synapses but increased extrasynaptic KAR, but not AMPAR, currents, suggesting that Clmp distinctly inhibits AMPAR and KAR responses. Behaviorally, Clmp deletion enhanced novel object recognition and susceptibility to kainate-induced seizures, without affecting contextual or auditory cued fear conditioning or pattern completion-based contextual fear conditioning. These results suggest that Clmp negatively regulates hippocampal excitatory synapse development and AMPAR and KAR responses in the neonatal hippocampal CA3 as well as object recognition and kainate seizure susceptibility in mice.
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Affiliation(s)
- Seil Jang
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science, Daejeon, South Korea
| | - Esther Yang
- Department of Anatomy and Division of Brain Korea 21, Biomedical Science, College of Medicine, Korea University, Seoul, South Korea
| | - Doyoun Kim
- Center for Drug Discovery Platform Research, Korea Research Institute of Chemical Technology (KRICT), Daejeon, South Korea
| | - Hyun Kim
- Department of Anatomy and Division of Brain Korea 21, Biomedical Science, College of Medicine, Korea University, Seoul, South Korea
| | - Eunjoon Kim
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science, Daejeon, South Korea.,Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
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Ellaithy A, Gonzalez-Maeso J, Logothetis DA, Levitz J. Structural and Biophysical Mechanisms of Class C G Protein-Coupled Receptor Function. Trends Biochem Sci 2020; 45:1049-1064. [PMID: 32861513 PMCID: PMC7642020 DOI: 10.1016/j.tibs.2020.07.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 07/22/2020] [Accepted: 07/30/2020] [Indexed: 02/07/2023]
Abstract
Groundbreaking structural and spectroscopic studies of class A G protein-coupled receptors (GPCRs), such as rhodopsin and the β2 adrenergic receptor, have provided a picture of how structural rearrangements between transmembrane helices control ligand binding, receptor activation, and effector coupling. However, the activation mechanism of other GPCR classes remains more elusive, in large part due to complexity in their domain assembly and quaternary structure. In this review, we focus on the class C GPCRs, which include metabotropic glutamate receptors (mGluRs) and gamma-aminobutyric acid B (GABAB) receptors (GABABRs) most prominently. We discuss the unique biophysical questions raised by the presence of large extracellular ligand-binding domains (LBDs) and constitutive homo/heterodimerization. Furthermore, we discuss how recent studies have begun to unravel how these fundamental class C GPCR features impact the processes of ligand binding, receptor activation, signal transduction, regulation by accessory proteins, and crosstalk with other GPCRs.
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Affiliation(s)
- Amr Ellaithy
- Department of Neurology, University of Iowa, Iowa City, IA 52242, USA; Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Javier Gonzalez-Maeso
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA
| | - Diomedes A Logothetis
- Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, MA 02115, USA; Department of Chemistry and Chemical Biology, College of Science and Center for Drug Discovery, Northeastern University, Boston, MA 02115, USA
| | - Joshua Levitz
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA.
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Rai D, Akagi T, Shimohata A, Ishii T, Gangi M, Maruyama T, Wada-Kiyama Y, Ogiwara I, Kaneda M. Involvement of the C-terminal domain in cell surface localization and G-protein coupling of mGluR6. J Neurochem 2020; 158:837-848. [PMID: 33067823 DOI: 10.1111/jnc.15217] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 05/25/2020] [Accepted: 10/11/2020] [Indexed: 01/05/2023]
Abstract
Metabotropic glutamate receptor 6, mGluR6, interacts with scaffold proteins and Gβγ subunits via its intracellular C-terminal domain (CTD). The mGluR6 pathway is critically involved in the retinal processing of visual signals. We herein investigated whether the CTD (residues 840-871) was necessary for mGluR6 cell surface localization and G-protein coupling using mGluR6-CTD mutants with immunocytochemistry, surface biotinylation assays, and electrophysiological approaches. We used 293T cells and primary hippocampal neurons as model systems. We examined C-terminally truncated mGluR6 and showed that the removal of up to residue 858 did not affect surface localization or glutamate-induced G-protein-mediated responses, whereas a 15-amino acid deletion (Δ857-871) impaired these functions. However, a 21-amino acid deletion (Δ851-871) restored surface localization and glutamate-dependent responses, which were again attenuated when the entire CTD was removed. The sequence alignment of group III mGluRs showed conserved amino acids resembling an ER retention motif in the CTD. These results suggest that the intracellular CTD is required for the cell surface transportation and receptor function of mGluR6, whereas it may contain regulatory elements for intracellular trafficking and signaling.
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Affiliation(s)
- Dilip Rai
- Department of Physiology, Nippon Medical School, Tokyo, Japan
| | - Takumi Akagi
- Department of Physiology, Nippon Medical School, Tokyo, Japan
| | | | - Toshiyuki Ishii
- Department of Physiology, Nippon Medical School, Tokyo, Japan
| | - Mie Gangi
- Department of Physiology, Nippon Medical School, Tokyo, Japan
| | - Takuma Maruyama
- Department of Physiology, Nippon Medical School, Tokyo, Japan
| | | | - Ikuo Ogiwara
- Department of Physiology, Nippon Medical School, Tokyo, Japan
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Park D, Park S, Song J, Kang M, Lee S, Horak M, Suh YH. N‐linked glycosylation of the mGlu7 receptor regulates the forward trafficking and transsynaptic interaction with Elfn1. FASEB J 2020; 34:14977-14996. [DOI: 10.1096/fj.202001544r] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 08/14/2020] [Accepted: 08/27/2020] [Indexed: 01/13/2023]
Affiliation(s)
- Da‐ha Park
- Department of Biomedical Sciences Neuroscience Research Institute Transplantation Research Institute Seoul National University College of Medicine Seoul South Korea
| | - Sunha Park
- Department of Biomedical Sciences Neuroscience Research Institute Transplantation Research Institute Seoul National University College of Medicine Seoul South Korea
| | - Jae‐man Song
- Department of Biomedical Sciences Neuroscience Research Institute Transplantation Research Institute Seoul National University College of Medicine Seoul South Korea
| | - Minji Kang
- Department of Biomedical Sciences Neuroscience Research Institute Transplantation Research Institute Seoul National University College of Medicine Seoul South Korea
| | - Sanghyeon Lee
- Department of Biomedical Sciences Neuroscience Research Institute Transplantation Research Institute Seoul National University College of Medicine Seoul South Korea
| | - Martin Horak
- Institute of Physiology of the Czech Academy of Sciences Institute of Experimental Medicine of the Czech Academy of Sciences Prague 4 Czech Republic
| | - Young Ho Suh
- Department of Biomedical Sciences Neuroscience Research Institute Transplantation Research Institute Seoul National University College of Medicine Seoul South Korea
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Interplay between cell-adhesion molecules governs synaptic wiring of cone photoreceptors. Proc Natl Acad Sci U S A 2020; 117:23914-23924. [PMID: 32879010 DOI: 10.1073/pnas.2009940117] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Establishment of functional synaptic connections in a selective manner is essential for nervous system operation. In mammalian retinas, rod and cone photoreceptors form selective synaptic connections with different classes of bipolar cells (BCs) to propagate light signals. While there has been progress in elucidating rod wiring, molecular mechanisms used by cones to establish functional synapses with BCs have remained unknown. Using an unbiased proteomic strategy in cone-dominant species, we identified the cell-adhesion molecule ELFN2 to be pivotal for the functional wiring of cones with the ON type of BC. It is selectively expressed in cones and transsynaptically recruits the key neurotransmitter receptor mGluR6 in ON-BCs to enable synaptic transmission. Remarkably, ELFN2 in cone terminals functions in synergy with a related adhesion molecule, ELFN1, and their concerted interplay during development specifies selective wiring and transmission of cone signals. These findings identify a synaptic connectivity mechanism of cones and illustrate how interplay between adhesion molecules and postsynaptic transmitter receptors orchestrates functional synaptic specification in a neural circuit.
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Agosto MA, Wensel TG. LRRTM4 is a member of the transsynaptic complex between rod photoreceptors and bipolar cells. J Comp Neurol 2020; 529:221-233. [PMID: 32390181 DOI: 10.1002/cne.24944] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/09/2020] [Accepted: 05/01/2020] [Indexed: 12/22/2022]
Abstract
Leucine rich repeat transmembrane (LRRTM) proteins are synaptic adhesion molecules with roles in synapse formation and signaling. LRRTM4 transcripts were previously shown to be enriched in rod bipolar cells (BCs), secondary neurons of the retina that form synapses with rod photoreceptors. Using two different antibodies, LRRTM4 was found to reside primarily at rod BC dendritic tips, where it colocalized with the transduction channel protein, TRPM1. LRRTM4 was not detected at dendritic tips of ON-cone BCs. Following somatic knockout of LRRTM4 in BCs by subretinal injection and electroporation of CRISPR/Cas9, LRRTM4 was abolished or reduced in the dendritic tips of transfected cells. Knockout cells had a normal complement of TRPM1 at their dendritic tips, while GPR179 accumulation was partially reduced. In experiments with heterologously expressed protein, the extracellular domain of LRRTM4 was found to engage in heparan-sulfate dependent binding with pikachurin. These results implicate LRRTM4 in the GPR179-pikachurin-dystroglycan transsynaptic complex at rod synapses.
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Affiliation(s)
- Melina A Agosto
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Theodore G Wensel
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA
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40
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Fisher NM, Gould RW, Gogliotti RG, McDonald AJ, Badivuku H, Chennareddy S, Buch AB, Moore AM, Jenkins MT, Robb WH, Lindsley CW, Jones CK, Conn PJ, Niswender CM. Phenotypic profiling of mGlu 7 knockout mice reveals new implications for neurodevelopmental disorders. GENES BRAIN AND BEHAVIOR 2020; 19:e12654. [PMID: 32248644 DOI: 10.1111/gbb.12654] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 03/03/2020] [Accepted: 03/26/2020] [Indexed: 12/17/2022]
Abstract
Neurodevelopmental disorders are characterized by deficits in communication, cognition, attention, social behavior and/or motor control. Previous studies have pointed to the involvement of genes that regulate synaptic structure and function in the pathogenesis of these disorders. One such gene, GRM7, encodes the metabotropic glutamate receptor 7 (mGlu7 ), a G protein-coupled receptor that regulates presynaptic neurotransmitter release. Mutations and polymorphisms in GRM7 have been associated with neurodevelopmental disorders in clinical populations; however, limited preclinical studies have evaluated mGlu7 in the context of this specific disease class. Here, we show that the absence of mGlu7 in mice is sufficient to alter phenotypes within the domains of social behavior, associative learning, motor function, epilepsy and sleep. Moreover, Grm7 knockout mice exhibit an attenuated response to amphetamine. These findings provide rationale for further investigation of mGlu7 as a potential therapeutic target for neurodevelopmental disorders such as idiopathic autism, attention deficit hyperactivity disorder and Rett syndrome.
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Affiliation(s)
- Nicole M Fisher
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA
| | - Robert W Gould
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA
| | - Rocco G Gogliotti
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA
| | - Annalise J McDonald
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA
| | - Hana Badivuku
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA
| | - Susmita Chennareddy
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA
| | - Aditi B Buch
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA
| | - Annah M Moore
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
| | - Matthew T Jenkins
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA
| | - W Hudson Robb
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA
| | - Craig W Lindsley
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA.,Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Carrie K Jones
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - P Jeffrey Conn
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Colleen M Niswender
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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41
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Marafi D, Mitani T, Isikay S, Hertecant J, Almannai M, Manickam K, Abou Jamra R, El-Hattab AW, Rajah J, Fatih JM, Du H, Karaca E, Bayram Y, Punetha J, Rosenfeld JA, Jhangiani SN, Boerwinkle E, Akdemir ZC, Erdin S, Hunter JV, Gibbs RA, Pehlivan D, Posey JE, Lupski JR. Biallelic GRM7 variants cause epilepsy, microcephaly, and cerebral atrophy. Ann Clin Transl Neurol 2020; 7:610-627. [PMID: 32286009 PMCID: PMC7261753 DOI: 10.1002/acn3.51003] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 02/10/2020] [Accepted: 02/11/2020] [Indexed: 01/29/2023] Open
Abstract
Objective Defects in ion channels and neurotransmitter receptors are implicated in developmental and epileptic encephalopathy (DEE). Metabotropic glutamate receptor 7 (mGluR7), encoded by GRM7, is a presynaptic G‐protein‐coupled glutamate receptor critical for synaptic transmission. We previously proposed GRM7 as a candidate disease gene in two families with neurodevelopmental disorders (NDDs). One additional family has been published since. Here, we describe three additional families with GRM7 biallelic variants and deeply characterize the associated clinical neurological and electrophysiological phenotype and molecular data in 11 affected individuals from six unrelated families. Methods Exome sequencing and family‐based rare variant analyses on a cohort of 220 consanguineous families with NDDs revealed three families with GRM7 biallelic variants; three additional families were identified through literature search and collaboration with a clinical molecular laboratory. Results We compared the observed clinical features and variants of 11 affected individuals from the six unrelated families. Identified novel deleterious variants included two homozygous missense variants (c.2671G>A:p.Glu891Lys and c.1973G>A:p.Arg685Gln) and one homozygous stop‐gain variant (c.1975C>T:p.Arg659Ter). Developmental delay, neonatal‐ or infantile‐onset epilepsy, and microcephaly were universal. Three individuals had hypothalamic–pituitary–axis dysfunction without pituitary structural abnormality. Neuroimaging showed cerebral atrophy and hypomyelination in a majority of cases. Two siblings demonstrated progressive loss of myelination by 2 years in both and an acquired microcephaly pattern in one. Five individuals died in early or late childhood. Conclusion Detailed clinical characterization of 11 individuals from six unrelated families demonstrates that rare biallelic GRM7 pathogenic variants can cause DEEs, microcephaly, hypomyelination, and cerebral atrophy.
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Affiliation(s)
- Dana Marafi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030.,Department of Pediatrics, Faculty of Medicine, Kuwait University, P.O. Box 24923, 13110, Safat, Kuwait
| | - Tadahiro Mitani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030
| | - Sedat Isikay
- Department of Physiotherapy and Rehabilitation, School of Health Sciences, Hasan Kalyoncu University, Gaziantep, 27000, Turkey
| | - Jozef Hertecant
- Pediatric Metabolic and Genetics Division, Tawam Hospital, Al Ain, Abu Dhabi, United Arab Emirates
| | - Mohammed Almannai
- Section of Medical Genetics, Children's Hospital, King Fahad Medical City, Riyadh, 11525, Saudi Arabia
| | - Kandamurugu Manickam
- Division of Genetic and Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio
| | - Rami Abou Jamra
- Institute of Human Genetics, University Medical Center Leipzig, 04103, Leipzig, Germany
| | - Ayman W El-Hattab
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah, 27272, United Arab Emirates
| | - Jaishen Rajah
- Sheikh Khalifa Medical City (SKMC), P.O. Box: 51900, Abu Dhabi, United Arab Emirates
| | - Jawid M Fatih
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030
| | - Haowei Du
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030
| | - Ender Karaca
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030
| | - Yavuz Bayram
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030
| | - Jaya Punetha
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030
| | - Jill A Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030
| | - Shalini N Jhangiani
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, 77030
| | - Eric Boerwinkle
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, 77030.,Human Genetics Center, University of Texas Health Science Center at Houston, Houston, Texas
| | - Zeynep C Akdemir
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030
| | - Serkan Erdin
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Jill V Hunter
- Texas Children's Hospital, Houston, Texas, 77030.,Department of Radiology, Baylor College of Medicine, Houston, Texas, 77030
| | - Richard A Gibbs
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, 77030
| | - Davut Pehlivan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030.,Texas Children's Hospital, Houston, Texas, 77030.,Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, 77030
| | - Jennifer E Posey
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, 77030.,Texas Children's Hospital, Houston, Texas, 77030.,Department of Pediatrics, Baylor College of Medicine, Houston, Texas, 77030
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Furukawa T, Ueno A, Omori Y. Molecular mechanisms underlying selective synapse formation of vertebrate retinal photoreceptor cells. Cell Mol Life Sci 2020; 77:1251-1266. [PMID: 31586239 PMCID: PMC11105113 DOI: 10.1007/s00018-019-03324-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 09/21/2019] [Accepted: 09/25/2019] [Indexed: 11/29/2022]
Abstract
In vertebrate central nervous systems (CNSs), highly diverse neurons are selectively connected via synapses, which are essential for building an intricate neural network. The vertebrate retina is part of the CNS and is comprised of a distinct laminar organization, which serves as a good model system to study developmental synapse formation mechanisms. In the retina outer plexiform layer, rods and cones, two types of photoreceptor cells, elaborate selective synaptic contacts with ON- and/or OFF-bipolar cell terminals as well as with horizontal cell terminals. In the mouse retina, three photoreceptor subtypes and at least 15 bipolar subtypes exist. Previous and recent studies have significantly progressed our understanding of how selective synapse formation, between specific subtypes of photoreceptor and bipolar cells, is designed at the molecular level. In the ON pathway, photoreceptor-derived secreted and transmembrane proteins directly interact in trans with the GRM6 (mGluR6) complex, which is localized to ON-bipolar cell dendritic terminals, leading to selective synapse formation. Here, we review our current understanding of the key factors and mechanisms underlying selective synapse formation of photoreceptor cells with bipolar and horizontal cells in the retina. In addition, we describe how defects/mutations of the molecules involved in photoreceptor synapse formation are associated with human retinal diseases and visual disorders.
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Affiliation(s)
- Takahisa Furukawa
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Akiko Ueno
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yoshihiro Omori
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
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43
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Berke B, Le L, Keshishian H. Target-dependent retrograde signaling mediates synaptic plasticity at the Drosophila neuromuscular junction. Dev Neurobiol 2020; 79:895-912. [PMID: 31950660 DOI: 10.1002/dneu.22731] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 01/08/2020] [Accepted: 01/09/2020] [Indexed: 12/26/2022]
Abstract
Neurons that innervate multiple targets often establish synapses with target-specific strengths, and local forms of synaptic plasticity. We have examined the molecular-genetic mechanisms that allow a single Drosophila motoneuron, the ventral Common Exciter (vCE), to establish connections with target-specific properties at its various synaptic partners. By driving transgenes in a subset of vCE's targets, we found that individual target cells are able to independently control the properties of vCE's innervating branch and synapses. This is achieved by means of a trans-synaptic growth factor secreted by the target cell. At the larval neuromuscular junction, postsynaptic glutamate receptor activity stimulates the release of the BMP4/5/6 homolog Glass bottom boat (Gbb). As larvae mature and motoneuron terminals grow, Gbb activates the R-Smad transcriptional regulator phosphorylated Mad (pMad) to facilitate presynaptic development. We found that manipulations affecting glutamate receptors or Gbb within subsets of target muscles led to local effects either specific to the manipulated muscle or by a limited gradient within the presynaptic branches. While presynaptic development depends on pMad transcriptional activity within the motoneuron nucleus, we find that the Gbb growth factor may also act locally within presynaptic terminals. Local Gbb signaling and presynaptic pMad accumulation within boutons may therefore participate in a "synaptic tagging" mechanism, to influence synaptic growth and plasticity in Drosophila.
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Affiliation(s)
- Brett Berke
- Molecular, Cellular, and Developmental Biology Department, Yale University, New Haven, CT, USA
| | - Linh Le
- University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Haig Keshishian
- Molecular, Cellular, and Developmental Biology Department, Yale University, New Haven, CT, USA
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44
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Park S, Kim GW, Kwon SH, Lee JS. Broad domains of histone H3 lysine 4 trimethylation in transcriptional regulation and disease. FEBS J 2020; 287:2891-2902. [PMID: 31967712 DOI: 10.1111/febs.15219] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 12/23/2019] [Accepted: 01/17/2020] [Indexed: 12/11/2022]
Abstract
Histone modifications affect transcription by changing the chromatin structure. In particular, histone H3 lysine 4 trimethylation (H3K4me3) is one of the most recognized epigenetic marks of active transcription. While many studies have provided evidence of the correlation between H3K4me3 and active transcription, details regarding the mechanism involved remain unclear. The first study on the broad H3K4me3 domain was reported in 2014; subsequently, the function of this domain has been studied in various cell types. In this review, we summarized the recent studies on the role of the broad H3K4me3 domain in transcription, development, memory formation, and several diseases, including cancer and autoimmune diseases. The broadest H3K4me3 domains are associated with increased transcriptional precision of cell-type-specific genes related to cell identity and other essential functions. The broad H3K4me3 domain regulates maternal zygotic activation in early mammalian development. In systemic autoimmune diseases, high expression of immune-responsive genes requires the presence of the broad H3K4me3 domain in the promoter-proximal regions. Transcriptional repression of tumor-suppressor genes is associated with the shortening of the broad H3K4me3 domains in cancer cells. Additionally, the broad H3K4me3 domain interacts with the super-enhancer to regulate cancer-associated genes. During memory formation, H3K4me3 breadth is regulated in the hippocampus CA1 neurons. Taken together, these findings indicate that H3K4me3 breadth is essential for the regulation of the transcriptional output across multiple cell types.
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Affiliation(s)
- Shinae Park
- Department of Molecular Bioscience, College of Biomedical Science, Kangwon National University, Chuncheon, Korea.,Critical Zone Frontier Research Laboratory, Kangwon National University, Chuncheon, Korea
| | - Go Woon Kim
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, Korea
| | - So Hee Kwon
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, Korea.,Department of Integrated OMICS for Biomedical Science, Yonsei University, Seoul, Korea
| | - Jung-Shin Lee
- Department of Molecular Bioscience, College of Biomedical Science, Kangwon National University, Chuncheon, Korea.,Critical Zone Frontier Research Laboratory, Kangwon National University, Chuncheon, Korea
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Orlandi C, Omori Y, Wang Y, Cao Y, Ueno A, Roux MJ, Condomitti G, de Wit J, Kanagawa M, Furukawa T, Martemyanov KA. Transsynaptic Binding of Orphan Receptor GPR179 to Dystroglycan-Pikachurin Complex Is Essential for the Synaptic Organization of Photoreceptors. Cell Rep 2020; 25:130-145.e5. [PMID: 30282023 PMCID: PMC6203450 DOI: 10.1016/j.celrep.2018.08.068] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 08/16/2018] [Accepted: 08/23/2018] [Indexed: 01/05/2023] Open
Abstract
Establishing synaptic contacts between neurons is paramount for nervous system function. This process involves transsynaptic interactions between a host of cell adhesion molecules that act in cooperation with the proteins of the extracellular matrix to specify uniquephysiological propertiesofindividual synaptic connections. However, understanding of the molecular mechanisms that generate functional diversity in an input-specific fashion is limited. In this study, we identify that major components of the extracellular matrix proteins present in the synaptic cleft—members oftheheparansulfateproteoglycan (HSPG) family—associate with the GPR158/179 group of orphan receptors. Using the mammalian retina as a model system, we demonstrate that the HSPG member Pikachurin, released by photoreceptors, recruits a key post-synaptic signaling complex of downstream ON-bipolar neurons in coordination with the presynaptic dystroglycan glycoprotein complex. We further demonstrate that this transsynaptic assembly plays an essential role in synaptic transmission of photoreceptor signals. Orlandi et al. identify transsynaptic assembly at photoreceptor synapses involving pre-synaptic dystrophindystroglycan complex and the postsynaptic orphan receptor GPR179 bridged by HSPG protein Pikachurin in the cleft and demonstrate its role in shaping transmission of photoreceptor signals.
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Affiliation(s)
- Cesare Orlandi
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Yoshihiro Omori
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Yuchen Wang
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Yan Cao
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Akiko Ueno
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Michel J Roux
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Université de Strasbourg, Centre National de la Recherche Scientifique, UMR7104, INSERM, U1258, Illkirch, France
| | - Giuseppe Condomitti
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium; KU Leuven, Department of Neurosciences, Herestraat 49, 3000 Leuven, Belgium
| | - Joris de Wit
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium; KU Leuven, Department of Neurosciences, Herestraat 49, 3000 Leuven, Belgium
| | - Motoi Kanagawa
- Division of Molecular Brain Science, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Takahisa Furukawa
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA.
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Dunn HA, Orlandi C, Martemyanov KA. Beyond the Ligand: Extracellular and Transcellular G Protein-Coupled Receptor Complexes in Physiology and Pharmacology. Pharmacol Rev 2019; 71:503-519. [PMID: 31515243 DOI: 10.1124/pr.119.018044] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
G protein-coupled receptors (GPCRs) remain one of the most successful targets of U.S. Food and Drug Administration-approved drugs. GPCR research has predominantly focused on the characterization of the intracellular interactome's contribution to GPCR function and pharmacology. However, emerging evidence uncovers a new dimension in the biology of GPCRs involving their extracellular and transcellular interactions that critically impact GPCR function and pharmacology. The seminal examples include a variety of adhesion GPCRs, such as ADGRLs/latrophilins, ADGRBs/brain angiogenesis inhibitors, ADGRG1/GPR56, ADGRG6/GPR126, ADGRE5/CD97, and ADGRC3/CELSR3. However, recent advances have indicated that class C GPCRs that contain large extracellular domains, including group III metabotropic glutamate receptors (mGluR4, mGluR6, mGluR7, mGluR8), γ-aminobutyric acid receptors, and orphans GPR158 and GPR179, can also participate in this form of transcellular regulation. In this review, we will focus on a variety of identified extracellular and transcellular GPCR-interacting partners, including teneurins, neurexins, integrins, fibronectin leucine-rich transmembranes, contactin-6, neuroligin, laminins, collagens, major prion protein, amyloid precursor protein, complement C1q-likes, stabilin-2, pikachurin, dystroglycan, complement decay-accelerating factor CD55, cluster of differentiation CD36 and CD90, extracellular leucine-rich repeat and fibronectin type III domain containing 1, and leucine-rich repeat, immunoglobulin-like domain and transmembrane domains. We provide an account on the diversity of extracellular and transcellular GPCR complexes and their contribution to key cellular and physiologic processes, including cell migration, axon guidance, cellular and synaptic adhesion, and synaptogenesis. Furthermore, we discuss models and mechanisms by which extracellular GPCR assemblies may regulate communication at cellular junctions. SIGNIFICANCE STATEMENT: G protein-coupled receptors (GPCRs) continue to be the prominent focus of pharmacological intervention for a variety of human pathologies. Although the majority of GPCR research has focused on the intracellular interactome, recent advancements have identified an extracellular dimension of GPCR modulation that alters accepted pharmacological principles of GPCRs. Herein, we describe known endogenous allosteric modulators acting on GPCRs both in cis and in trans.
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Affiliation(s)
- Henry A Dunn
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida
| | - Cesare Orlandi
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida
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ELFN2 is a postsynaptic cell adhesion molecule with essential roles in controlling group III mGluRs in the brain and neuropsychiatric behavior. Mol Psychiatry 2019; 24:1902-1919. [PMID: 31485013 PMCID: PMC6874751 DOI: 10.1038/s41380-019-0512-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Revised: 07/17/2019] [Accepted: 07/26/2019] [Indexed: 12/17/2022]
Abstract
The functional characterization of the GPCR interactome has predominantly focused on intracellular binding partners; however, the recent emergence of transsynaptic GPCR complexes represents an additional dimension to GPCR function that has previously been unaccounted for in drug discovery. Here, we characterize ELFN2 as a novel postsynaptic adhesion molecule with a distinct expression pattern throughout the brain and a selective binding with group III metabotropic glutamate receptors (mGluRs) in trans. Using a transcellular GPCR signaling platform, we report that ELFN2 critically alters group III mGluR secondary messenger signaling by directly altering G protein coupling kinetics and efficacy. Loss of ELFN2 in mice results in the selective downregulation of group III mGluRs and dysregulated glutamatergic synaptic transmission. Elfn2 knockout (Elfn2 KO) mice also feature a range of neuropsychiatric manifestations including seizure susceptibility, hyperactivity, and anxiety/compulsivity, which can be rescued by pharmacological augmentation of group III mGluRs. Thus, we conclude that extracellular transsynaptic scaffolding by ELFN2 in the brain is a cardinal organizational feature of group III mGluRs essential for their signaling properties and brain function.
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Cingolani LA, Vitale C, Dityatev A. Intra- and Extracellular Pillars of a Unifying Framework for Homeostatic Plasticity: A Crosstalk Between Metabotropic Receptors and Extracellular Matrix. Front Cell Neurosci 2019; 13:513. [PMID: 31803023 PMCID: PMC6877475 DOI: 10.3389/fncel.2019.00513] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Accepted: 10/29/2019] [Indexed: 11/18/2022] Open
Abstract
In the face of chronic changes in incoming sensory inputs, neuronal networks are capable of maintaining stable conditions of electrical activity over prolonged periods of time by adjusting synaptic strength, to amplify or dampen incoming inputs [homeostatic synaptic plasticity (HSP)], or by altering the intrinsic excitability of individual neurons [homeostatic intrinsic plasticity (HIP)]. Emerging evidence suggests a synergistic interplay between extracellular matrix (ECM) and metabotropic receptors in both forms of homeostatic plasticity. Activation of dopaminergic, serotonergic, or glutamate metabotropic receptors stimulates intracellular signaling through calmodulin-dependent protein kinase II, protein kinase A, protein kinase C, and inositol trisphosphate receptors, and induces changes in expression of ECM molecules and proteolysis of both ECM molecules (lecticans) and ECM receptors (NPR, CD44). The resulting remodeling of perisynaptic and synaptic ECM provides permissive conditions for HSP and plays an instructive role by recruiting additional signaling cascades, such as those through metabotropic glutamate receptors and integrins. The superimposition of all these signaling events determines intracellular and diffusional trafficking of ionotropic glutamate receptors, resulting in HSP and modulation of conditions for inducing Hebbian synaptic plasticity (i.e., metaplasticity). It also controls cell-surface delivery and activity of voltage- and Ca2+-gated ion channels, resulting in HIP. These mechanisms may modify epileptogenesis and become a target for therapeutic interventions.
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Affiliation(s)
- Lorenzo A. Cingolani
- Department of Life Sciences, University of Trieste, Trieste, Italy
- Center for Synaptic Neuroscience and Technology (NSYN), Istituto Italiano di Tecnologia, Genoa, Italy
| | - Carmela Vitale
- Center for Synaptic Neuroscience and Technology (NSYN), Istituto Italiano di Tecnologia, Genoa, Italy
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Alexander Dityatev
- Molecular Neuroplasticity, German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
- Medical Faculty, Otto von Guericke University Magdeburg, Magdeburg, Germany
- Center for Behavioral Brain Sciences, Magdeburg, Germany
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49
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Altered Dynamics of Canonical Feedback Inhibition Predicts Increased Burst Transmission in Chronic Epilepsy. J Neurosci 2019; 39:8998-9012. [PMID: 31519822 DOI: 10.1523/jneurosci.2594-18.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 08/28/2019] [Accepted: 09/04/2019] [Indexed: 11/21/2022] Open
Abstract
Inhibitory interneurons, organized into canonical feedforward and feedback motifs, play a key role in controlling normal and pathological neuronal activity. We demonstrate prominent quantitative changes in the dynamics of feedback inhibition in a rat model of chronic epilepsy (male Wistar rats). Systematic interneuron recordings revealed a large decrease in intrinsic excitability of basket cells and oriens-lacunosum moleculare interneurons in epileptic animals. Additionally, the temporal dynamics of interneuron recruitment by recurrent feedback excitation were strongly altered, resulting in a profound loss of initial feedback inhibition during synchronous CA1 pyramidal activity. Biophysically constrained models of the complete feedback circuit motifs of normal and epileptic animals revealed that, as a consequence of altered feedback inhibition, burst activity arising in CA3 is more strongly converted to a CA1 output. This suggests that altered dynamics of feedback inhibition promote the transmission of epileptiform bursts to hippocampal projection areas.SIGNIFICANCE STATEMENT We quantitatively characterized changes of the CA1 feedback inhibitory circuit in a model of chronic temporal lobe epilepsy. This study shows, for the first time, that dynamic recruitment of inhibition in feedback circuits is altered and establishes the cellular mechanisms for this change. Computational modeling revealed that the observed changes are likely to systematically alter CA1 input-output properties leading to (1) increased seizure propagation through CA1 and (2) altered computation of synchronous CA3 input.
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50
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Urban-Ciecko J, Jouhanneau JS, Myal SE, Poulet JFA, Barth AL. Precisely Timed Nicotinic Activation Drives SST Inhibition in Neocortical Circuits. Neuron 2019; 97:611-625.e5. [PMID: 29420933 DOI: 10.1016/j.neuron.2018.01.037] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 10/30/2017] [Accepted: 01/12/2018] [Indexed: 11/13/2022]
Abstract
Sleep, waking, locomotion, and attention are associated with cell-type-specific changes in neocortical activity. The effect of brain state on circuit output requires understanding of how neuromodulators influence specific neuronal classes and their synapses, with normal patterns of neuromodulator release from endogenous sources. We investigated the state-dependent modulation of a ubiquitous feedforward inhibitory motif in mouse sensory cortex, local pyramidal (Pyr) inputs onto somatostatin (SST)-expressing interneurons. Paired whole-cell recordings in acute brain slices and in vivo showed that Pyr-to-SST synapses are remarkably weak, with failure rates approaching 80%. Pharmacological screening revealed that cholinergic agonists uniquely enhance synaptic efficacy. Brief, optogenetically gated acetylcholine release dramatically enhanced Pyr-to-SST input, via nicotinic receptors and presynaptic PKA signaling. Importantly, endogenous acetylcholine release preferentially activated nicotinic, not muscarinic, receptors, thus differentiating drug effects from endogenous neurotransmission. Brain state- and synapse-specific unmasking of synapses may be a powerful way to functionally rewire cortical circuits dependent on behavioral demands.
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Affiliation(s)
- Joanna Urban-Ciecko
- Department of Biological Sciences and Center for the Neural Basis of Cognition, Carnegie Mellon University, Pittsburgh, PA 15213, USA; Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Pasteur str. 3, 02-093 Warsaw, Poland
| | - Jean-Sebastien Jouhanneau
- Department of Neuroscience, Max Delbrück Center for Molecular Medicine (MDC), Berlin-Buch, Robert-Rössle-Str. 10, 13092 Berlin, Germany; Cluster of Excellence NeuroCure, Neuroscience Research Center, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Stephanie E Myal
- Department of Biological Sciences and Center for the Neural Basis of Cognition, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - James F A Poulet
- Department of Neuroscience, Max Delbrück Center for Molecular Medicine (MDC), Berlin-Buch, Robert-Rössle-Str. 10, 13092 Berlin, Germany; Cluster of Excellence NeuroCure, Neuroscience Research Center, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Alison L Barth
- Department of Biological Sciences and Center for the Neural Basis of Cognition, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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