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Ayhan S, Dursun A. ELFN1 is a new extracellular matrix (ECM)-associated protein. Life Sci 2024; 352:122900. [PMID: 38986898 DOI: 10.1016/j.lfs.2024.122900] [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: 04/15/2024] [Revised: 06/30/2024] [Accepted: 07/06/2024] [Indexed: 07/12/2024]
Abstract
AIMS The ELFN1, discovered in 2007, is a single-pass transmembrane protein. Studies conducted thus far to elucidate the function of the Elfn1 have been limited only to animal studies. These studies have reported that ELFN1 is a universal binding partner of metabotropic glutamate receptors (mGluRs) in the central nervous system and its functional deficiency has been associated with the pathogenesis of neurological and neuropsychiatric diseases. In 2021, we described the first disease-associated human ELFN1 pathogenic gene mutation. Severe joint laxity, which was the most striking finding of this new disease and was clearly seen in the patients since early infancy, showed that the ELFN1 may have a possible function in the connective tissue besides the nervous system. Here, we present the first experimental evidence of the extracellular matrix (ECM)-related function of the ELFN1. MATERIALS AND METHODS Primary skin fibroblasts were isolated from the skin biopsies of ELFN1 mutated patients and healthy foreskin donors. For the clinical trial in a dish, in vitro ECM and DEM (decellularized ECM) models were created from skin fibroblasts. All the in vitro models were comparatively characterized and analyzed. KEY FINDINGS The mutation in the ELFN1 signal peptide region of patients resulted in a severe lack of ELFN1 expression and dramatically altered the characteristic morphology and behavior (growth, proliferation, and motility) of fibroblasts. SIGNIFICANCE We propose that ELFN1 is involved in the cell-ECM attachment, and its deficiency is critical enough to cause a loss of cell motility and soft ECM stiffness.
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Affiliation(s)
- Selda Ayhan
- Department of Pediatrics Metabolism, Institute of Child Health, Hacettepe University, Sıhhıye, Ankara 06100, Turkey.
| | - Ali Dursun
- Department of Pediatrics Metabolism, Faculty of Medicine, Hacettepe University, Sıhhıye, Ankara 06100, Turkey.
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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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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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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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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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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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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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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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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] [MESH Headings] [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.
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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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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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11
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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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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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13
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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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14
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Kim HY, Yang YR, Hwang H, Lee HE, Jang HJ, Kim J, Yang E, Kim H, Rhim H, Suh PG, Kim JI. Deletion of PLCγ1 in GABAergic neurons increases seizure susceptibility in aged mice. Sci Rep 2019; 9:17761. [PMID: 31780806 PMCID: PMC6882884 DOI: 10.1038/s41598-019-54477-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 11/13/2019] [Indexed: 02/08/2023] Open
Abstract
Synaptic inhibition plays a fundamental role in the information processing of neural circuits. It sculpts excitatory signals and prevents hyperexcitability of neurons. Owing to these essential functions, dysregulated synaptic inhibition causes a plethora of neurological disorders, including epilepsy, autism, and schizophrenia. Among these disorders, epilepsy is associated with abnormal hyperexcitability of neurons caused by the deficits of GABAergic neuron or decreased GABAergic inhibition at synapses. Although many antiepileptic drugs are intended to improve GABA-mediated inhibition, the molecular mechanisms of synaptic inhibition regulated by GABAergic neurons are not fully understood. Increasing evidence indicates that phospholipase Cγ1 (PLCγ1) is involved in the generation of seizure, while the causal relationship between PLCγ1 and seizure has not been firmly established yet. Here, we show that genetic deletion of PLCγ1 in GABAergic neurons leads to handling-induced seizure in aged mice. In addition, aged Plcg1F/F; Dlx5/6-Cre mice exhibit other behavioral alterations, including hypoactivity, reduced anxiety, and fear memory deficit. Notably, inhibitory synaptic transmission as well as the number of inhibitory synapses are decreased in the subregions of hippocampus. These findings suggest that PLCγ1 may be a key determinant of maintaining both inhibitory synapses and synaptic transmission, potentially contributing to the regulation of E/I balance in the hippocampus.
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Affiliation(s)
- Hye Yun Kim
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Yong Ryoul Yang
- Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea
| | - Hongik Hwang
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, 136-791, Republic of Korea
| | - Ha-Eun Lee
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Hyun-Jun Jang
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Jeongyeon Kim
- Korea Brain Research Institute (KBRI), Daegu, 41062, Republic of Korea
| | - Esther Yang
- Department of Anatomy, College of Medicine, Korea University, Seoul, 136-705, Republic of Korea
| | - Hyun Kim
- Department of Anatomy, College of Medicine, Korea University, Seoul, 136-705, Republic of Korea
| | - Hyewhon Rhim
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, 136-791, Republic of Korea
| | - Pann-Ghill Suh
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea. .,Korea Brain Research Institute (KBRI), Daegu, 41062, Republic of Korea.
| | - Jae-Ick Kim
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea.
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15
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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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16
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Oprea TI. Exploring the dark genome: implications for precision medicine. Mamm Genome 2019; 30:192-200. [PMID: 31270560 DOI: 10.1007/s00335-019-09809-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 06/15/2019] [Indexed: 01/08/2023]
Abstract
The increase in the number of both patients and healthcare practitioners who grew up using the Internet and computers (so-called "digital natives") is likely to impact the practice of precision medicine, and requires novel platforms for data integration and mining, as well as contextualized information retrieval. The "Illuminating the Druggable Genome Knowledge Management Center" (IDG KMC) quantifies data availability from a wide range of chemical, biological, and clinical resources, and has developed platforms that can be used to navigate understudied proteins (the "dark genome"), and their potential contribution to specific pathologies. Using the "Target Importance and Novelty Explorer" (TIN-X) highlights the role of LRRC10 (a dark gene) in dilated cardiomyopathy. Combining mouse and human phenotype data leads to increased strength of evidence, which is discussed for four additional dark genes: SLX4IP and its role in glucose metabolism, the role of HSF2BP in coronary artery disease, the involvement of ELFN1 in attention-deficit hyperactivity disorder and the role of VPS13D in mouse neural tube development and its confirmed role in childhood onset movement disorders. The workflow and tools described here are aimed at guiding further experimental research, particularly within the context of precision medicine.
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Affiliation(s)
- Tudor I Oprea
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, USA. .,UNM Comprehensive Cancer Center, Albuquerque, NM, USA. .,Department of Rheumatology and Inflammation Research, Institute of Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden. .,Faculty of Health and Medical Sciences, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark.
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17
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Stachniak TJ, Sylwestrak EL, Scheiffele P, Hall BJ, Ghosh A. Elfn1-Induced Constitutive Activation of mGluR7 Determines Frequency-Dependent Recruitment of Somatostatin Interneurons. J Neurosci 2019; 39:4461-4474. [PMID: 30940718 PMCID: PMC6554623 DOI: 10.1523/jneurosci.2276-18.2019] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Revised: 02/14/2019] [Accepted: 03/22/2019] [Indexed: 11/21/2022] Open
Abstract
Excitatory synapses onto somatostatin (SOM) interneurons show robust short-term facilitation. This hallmark feature of SOM interneurons arises from a low initial release probability that regulates the recruitment of interneurons in response to trains of action potentials. Previous work has shown that Elfn1 (extracellular leucine rich repeat and fibronectin Type III domain containing 1) is necessary to generate facilitating synapses onto SOM neurons by recruitment of two separate presynaptic components: mGluR7 (metabotropic glutamate receptor 7) and GluK2-KARs (kainate receptors containing glutamate receptor, ionotropic, kainate 2). Here, we identify how a transsynaptic interaction between Elfn1 and mGluR7 constitutively reduces initial release probability onto mouse cortical SOM neurons. Elfn1 produces glutamate-independent activation of mGluR7 via presynaptic clustering, resulting in a divergence from the canonical "autoreceptor" role of Type III mGluRs, and substantially altering synaptic pharmacology. This structurally induced determination of initial release probability is present at both layer 2/3 and layer 5 synapses. In layer 2/3 SOM neurons, synaptic facilitation in response to spike trains is also dependent on presynaptic GluK2-KARs. In contrast, layer 5 SOM neurons do not exhibit presynaptic GluK2-KAR activity at baseline and show reduced facilitation. GluK2-KAR engagement at synapses onto layer 5 SOM neurons can be induced by calmodulin activation, suggesting that synaptic function can be dynamically regulated. Thus, synaptic facilitation onto SOM interneurons is mediated both by constitutive mGluR7 recruitment by Elfn1 and regulated GluK2-KAR recruitment, which determines the extent of interneuron recruitment in different cortical layers.SIGNIFICANCE STATEMENT This study identifies a novel mechanism for generating constitutive GPCR activity through a transsynaptic Elfn1/mGluR7 structural interaction. The resulting tonic suppression of synaptic release probability deviates from canonical autoreceptor function. Constitutive suppression delays the activation of somatostatin interneurons in circuits, necessitating high-frequency activity for somatostatin interneuron recruitment. Furthermore, variations in the synaptic proteome generate layer-specific differences in facilitation at pyr → SOM synapses. The presence of GluK2 kainate receptors in L2/3 enhances synaptic transmission during prolonged activity. Thus, layer-specific synaptic properties onto somatostatin interneurons are mediated by both constitutive mGluR7 recruitment and regulated GluK2 kainate receptor recruitment, revealing a mechanism that generates diversity in physiological responses of interneurons.
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Affiliation(s)
- Tevye Jason Stachniak
- F. Hoffmann-La Roche Ltd, Roche Innovation Center Basel, Basel 4051, Switzerland
- University of Basel, Departement Biozentrum, Basel 4056, Switzerland, and
- Biogen, Cambridge, Massachusetts 02142
| | - Emily Lauren Sylwestrak
- F. Hoffmann-La Roche Ltd, Roche Innovation Center Basel, Basel 4051, Switzerland
- Stanford University, Department of Bioengineering, Stanford, California 94305
- University of Basel, Departement Biozentrum, Basel 4056, Switzerland, and
| | - Peter Scheiffele
- University of Basel, Departement Biozentrum, Basel 4056, Switzerland, and
| | - Benjamin J Hall
- F. Hoffmann-La Roche Ltd, Roche Innovation Center Basel, Basel 4051, Switzerland
| | - Anirvan Ghosh
- F. Hoffmann-La Roche Ltd, Roche Innovation Center Basel, Basel 4051, Switzerland,
- Biogen, Cambridge, Massachusetts 02142
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18
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Aref-Eshghi E, Bend EG, Colaiacovo S, Caudle M, Chakrabarti R, Napier M, Brick L, Brady L, Carere DA, Levy MA, Kerkhof J, Stuart A, Saleh M, Beaudet AL, Li C, Kozenko M, Karp N, Prasad C, Siu VM, Tarnopolsky MA, Ainsworth PJ, Lin H, Rodenhiser DI, Krantz ID, Deardorff MA, Schwartz CE, Sadikovic B. Diagnostic Utility of Genome-wide DNA Methylation Testing in Genetically Unsolved Individuals with Suspected Hereditary Conditions. Am J Hum Genet 2019; 104:685-700. [PMID: 30929737 DOI: 10.1016/j.ajhg.2019.03.008] [Citation(s) in RCA: 107] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 03/05/2019] [Indexed: 12/13/2022] Open
Abstract
Conventional genetic testing of individuals with neurodevelopmental presentations and congenital anomalies (ND/CAs), i.e., the analysis of sequence and copy number variants, leaves a substantial proportion of them unexplained. Some of these cases have been shown to result from DNA methylation defects at a single locus (epi-variants), while others can exhibit syndrome-specific DNA methylation changes across multiple loci (epi-signatures). Here, we investigate the clinical diagnostic utility of genome-wide DNA methylation analysis of peripheral blood in unresolved ND/CAs. We generate a computational model enabling concurrent detection of 14 syndromes using DNA methylation data with full accuracy. We demonstrate the ability of this model in resolving 67 individuals with uncertain clinical diagnoses, some of whom had variants of unknown clinical significance (VUS) in the related genes. We show that the provisional diagnoses can be ruled out in many of the case subjects, some of whom are shown by our model to have other diseases initially not considered. By applying this model to a cohort of 965 ND/CA-affected subjects without a previous diagnostic assumption and a separate assessment of rare epi-variants in this cohort, we identify 15 case subjects with syndromic Mendelian disorders, 12 case subjects with imprinting and trinucleotide repeat expansion disorders, as well as 106 case subjects with rare epi-variants, a portion of which involved genes clinically or functionally linked to the subjects' phenotypes. This study demonstrates that genomic DNA methylation analysis can facilitate the molecular diagnosis of unresolved clinical cases and highlights the potential value of epigenomic testing in the routine clinical assessment of ND/CAs.
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19
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Fisher NM, Seto M, Lindsley CW, Niswender CM. Metabotropic Glutamate Receptor 7: A New Therapeutic Target in Neurodevelopmental Disorders. Front Mol Neurosci 2018; 11:387. [PMID: 30405350 PMCID: PMC6206046 DOI: 10.3389/fnmol.2018.00387] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 10/01/2018] [Indexed: 12/27/2022] Open
Abstract
Neurodevelopmental disorders (NDDs) are characterized by a wide range of symptoms including delayed speech, intellectual disability, motor dysfunction, social deficits, breathing problems, structural abnormalities, and epilepsy. Unfortunately, current treatment strategies are limited and innovative new approaches are sorely needed to address these complex diseases. The metabotropic glutamate receptors are a class of G protein-coupled receptors that act to modulate neurotransmission across many brain structures. They have shown great promise as drug targets for numerous neurological and psychiatric diseases. Moreover, the development of subtype-selective allosteric modulators has allowed detailed studies of each receptor subtype. Here, we focus on the metabotropic glutamate receptor 7 (mGlu7) as a potential therapeutic target for NDDs. mGlu7 is expressed widely throughout the brain in regions that correspond to the symptom domains listed above and has established roles in synaptic physiology and behavior. Single nucleotide polymorphisms and mutations in the GRM7 gene have been associated with idiopathic autism and other NDDs in patients. In rodent models, existing literature suggests that decreased mGlu7 expression and/or function may lead to symptoms that overlap with those of NDDs. Furthermore, potentiation of mGlu7 activity has shown efficacy in a mouse model of Rett syndrome. In this review, we summarize current findings that provide rationale for the continued development of mGlu7 modulators as potential therapeutics.
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Affiliation(s)
- Nicole M Fisher
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN, United States
| | - Mabel Seto
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN, United States
| | - Craig W Lindsley
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN, United States.,Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Colleen M Niswender
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN, United States.,Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN, United States
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20
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Muzyka VV, Brooks M, Badea TC. Postnatal developmental dynamics of cell type specification genes in Brn3a/Pou4f1 Retinal Ganglion Cells. Neural Dev 2018; 13:15. [PMID: 29958540 PMCID: PMC6025728 DOI: 10.1186/s13064-018-0110-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 06/06/2018] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND About 20-30 distinct Retinal Ganglion Cell (RGC) types transmit visual information from the retina to the brain. The developmental mechanisms by which RGCs are specified are still largely unknown. Brn3a is a member of the Brn3/Pou4f transcription factor family, which contains key regulators of RGC postmitotic specification. In particular, Brn3a ablation results in the loss of RGCs with small, thick and dense dendritic arbors ('midget-like' RGCs), and morphological changes in other RGC subpopulations. To identify downstream molecular mechanisms underlying Brn3a effects on RGC numbers and morphology, our group recently performed a RNA deep sequencing screen for Brn3a transcriptional targets in mouse RGCs and identified 180 candidate transcripts. METHODS We now focus on a subset of 28 candidate genes encoding potential cell type determinant proteins. We validate and further define their retinal expression profile at five postnatal developmental time points between birth and adult stage, using in situ hybridization (ISH), RT-PCR and fluorescent immunodetection (IIF). RESULTS We find that a majority of candidate genes are enriched in the ganglion cell layer during early stages of postnatal development, but dynamically change their expression profile. We also document transcript-specific expression differences for two example candidates, using RT-PCR and ISH. Brn3a dependency could be confirmed by ISH and IIF only for a fraction of our candidates. CONCLUSIONS Amongst our candidate Brn3a target genes, a majority demonstrated ganglion cell layer specificity, however only around two thirds showed Brn3a dependency. Some were previously implicated in RGC type specification, while others have known physiological functions in RGCs. Only three genes were found to be consistently regulated by Brn3a throughout postnatal retina development - Mapk10, Tusc5 and Cdh4.
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Affiliation(s)
| | - Matthew Brooks
- Genomics Core, Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, NIH, Building 6, Room 331B Center Drive, Bethesda, MD, 20892-0610, USA
| | - Tudor Constantin Badea
- Retinal Circuit Development & Genetics Unit, Building 6, Room 331B Center Drive, Bethesda, MD, 20892-0610, USA.
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21
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Park D, Bae S, Yoon TH, Ko J. Molecular Mechanisms of Synaptic Specificity: Spotlight on Hippocampal and Cerebellar Synapse Organizers. Mol Cells 2018; 41:373-380. [PMID: 29665671 PMCID: PMC5974614 DOI: 10.14348/molcells.2018.0081] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Revised: 03/30/2018] [Accepted: 04/02/2018] [Indexed: 12/13/2022] Open
Abstract
Synapses and neural circuits form with exquisite specificity during brain development to allow the precise and appropriate flow of neural information. Although this property of synapses and neural circuits has been extensively investigated for more than a century, molecular mechanisms underlying this property are only recently being unveiled. Recent studies highlight several classes of cell-surface proteins as organizing hubs in building structural and functional architectures of specific synapses and neural circuits. In the present mini-review, we discuss recent findings on various synapse organizers that confer the distinct properties of specific synapse types and neural circuit architectures in mammalian brains, with a particular focus on the hippocampus and cerebellum.
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Affiliation(s)
- Dongseok Park
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988,
Korea
| | - Sungwon Bae
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988,
Korea
| | - Taek Han Yoon
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988,
Korea
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988,
Korea
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22
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Synaptic adhesion protein ELFN1 is a selective allosteric modulator of group III metabotropic glutamate receptors in trans. Proc Natl Acad Sci U S A 2018; 115:5022-5027. [PMID: 29686062 DOI: 10.1073/pnas.1722498115] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Functional characterization of the GPCR interactome has been focused predominantly on intracellular interactions, yet GPCRs are increasingly found in complex with extracellular proteins. Extracellular leucine-rich repeat fibronectin type III domain containing 1 (ELFN1) was recently reported to physically anchor mGluR6 and mGluR7 across retinal and hippocampal synapses, respectively; however, the consequence of transsynaptic interactions on properties and pharmacology of these receptors are unknown. In the current study, we explore the effects of ELFN1 on mGluR signaling and pharmacology. First, we established the binding specificity of ELFN1 and found it to be recruited selectively to all group III mGluRs (mGluR4, mGluR6, mGluR7, and mGluR8), but not other mGluR species. Using site-directed mutagenesis we mapped binding determinants of this interaction to two distinct sites on the ELFN1 ectodomain. To evaluate functional aspects of the interaction, we developed a transcellular signaling assay in reconstituted HEK293 cells which monitors changes in mGluR activity in one cell following its exposure to separate ELFN1-containing cells. Using this platform, we found that ELFN1 acts as an allosteric modulator of class III mGluR activity in suppressing cAMP accumulation: altering both agonist-induced and constitutive receptor activity. Using bioluminescence resonance energy transfer-based real-time kinetic assays, we established that ELFN1 alters the ability of mGluRs to activate G proteins. Our findings demonstrate that core properties of class III mGluRs can be altered via extracellular interactions with ELFN1 which serves as a transsynaptic allosteric modulator for these receptors. Furthermore, our unique assay platform opens avenues for exploring transcellular/transsynaptic pharmacology of other GPCR transcomplexes.
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23
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Blood Transcriptional Signatures for Disease Progression in a Rat Model of Osteoarthritis. Int J Genomics 2017; 2017:1746426. [PMID: 28758108 PMCID: PMC5512050 DOI: 10.1155/2017/1746426] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Revised: 05/17/2017] [Accepted: 05/29/2017] [Indexed: 01/05/2023] Open
Abstract
Biomarkers of osteoarthritis (OA) that can accurately diagnose the disease at the earliest stage would significantly support efforts to develop treatments for prevention and early intervention. We have sought to determine the time course of alterations in peripheral blood gene expression profile associated with the development of OA. Blood samples were collected from a tail vein of individual rats with monosodium iodoacetate- (MIA-) induced OA (2, 14, 21, and 28 days after the treatment). We used whole-genome microarrays to reveal OA-related transcriptional alterations of 72 transcripts. Three main groups of coexpressed genes revealed diverse time-dependent profiles of up- and downregulation. Functional links that connect expression of the gradually downregulated genes to the G13 signaling pathway were indicated. The mRNA abundance levels of the identified transcripts were further analyzed in publicly available gene expression dataset obtained from a GARP study cohort of OA patients. We revealed three-gene signature differentially expressed in both rat and human blood (TNK2, KCTD2, and WDR37). The alterations in expression of the selected transcripts in peripheral blood samples of the patients indicate heterogeneity of the OA profiles potentially related to disease progress and severity of clinical symptoms. Our study identifies several potential stage-specific biomarkers of OA progression.
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24
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Li J, Chen L, Wang N, Jiang G, Wu Y, Zhang Y. Effect of synaptic adhesion-like molecule 3 on epileptic seizures: Evidence from animal models. Epilepsy Behav 2017; 69:18-23. [PMID: 28222338 DOI: 10.1016/j.yebeh.2016.11.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 11/10/2016] [Accepted: 11/11/2016] [Indexed: 01/05/2023]
Abstract
Axonal sprouting and synaptic reorganization are the primary pathophysiological characteristics of epilepsy. Recent studies demonstrated that synaptic adhesion-like molecule 3 (SALM3) is highly expressed in the central nervous system and plays important roles in neurite outgrowth, branching, and axon guidance, mechanisms that are also observed in epilepsy. However, the expression of SALM3 in the epileptic brain and the effect of SALM3 in the pathogenesis of epilepsy remain unclear. The aims of this study were to investigate SALM3 expression in rat models of epilepsy and to explore the functional significance of SALM3 in epilepsy. We demonstrated that SALM3 was expressed at significantly higher levels in epileptic rats compared with controls. Inhibition of SALM3 by SALM3 shRNA inhibited status epilepticus in the acute stage of disease and decreased spontaneous recurrent seizures in the Lithium-pilocarpine model of chronic stages of epilepsy. Consistent with these findings, SALM3 shRNA significantly prolonged the latent period in the PTZ kindling model. Our study suggests that the overexpression of SALM3 might be associated with epileptogenesis and that selectively inhibiting SALM3 may have therapeutic potential in treating epilepsy.
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Affiliation(s)
- Jie Li
- Department of Neurology, Xinxiang Medical University, Weihui 453100, China.
| | - Ling Chen
- Department of Neurology, Kunming Medical University, Kunming 650032, China
| | - Na Wang
- Department of Neurology, Henan Provincial People's Hospital, Zhengzhou University, Zhengzhou 450003, China
| | - Guohui Jiang
- Department of Neurology, North Sichuan Medical University, Nanchong 637000, China
| | - Yuqing Wu
- Department of Neurology, Xinxiang Medical University, Weihui 453100, China
| | - Yi Zhang
- Department of Neurology, Xinxiang Medical University, Weihui 453100, China
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25
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Stafstrom CE, Staedtke V, Comi AM. Epilepsy Mechanisms in Neurocutaneous Disorders: Tuberous Sclerosis Complex, Neurofibromatosis Type 1, and Sturge-Weber Syndrome. Front Neurol 2017; 8:87. [PMID: 28367137 PMCID: PMC5355446 DOI: 10.3389/fneur.2017.00087] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 02/24/2017] [Indexed: 01/27/2023] Open
Abstract
Neurocutaneous disorders are multisystem diseases affecting skin, brain, and other organs. Epilepsy is very common in the neurocutaneous disorders, affecting up to 90% of patients with tuberous sclerosis complex (TSC) and Sturge–Weber syndrome (SWS), for example. The mechanisms underlying the increased predisposition to brain hyperexcitability differ between disorders, yet some molecular pathways overlap. For instance, the mechanistic target of rapamycin (mTOR) signaling cascade plays a central role in seizures and epileptogenesis in numerous acquired and genetic disorders, including several neurocutaneous disorders. Potential routes for target-specific treatments are emerging as the genetic and molecular pathways involved in neurocutaneous disorders become increasingly understood. This review explores the clinical features and mechanisms of epilepsy in three common neurocutaneous disorders—TSC, neurofibromatosis type 1, and SWS.
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Affiliation(s)
- Carl E Stafstrom
- Division of Pediatric Neurology, Department of Neurology, Johns Hopkins University School of Medicine , Baltimore, MD , USA
| | - Verena Staedtke
- Division of Pediatric Neurology, Department of Neurology, Johns Hopkins University School of Medicine , Baltimore, MD , USA
| | - Anne M Comi
- Department of Neurology, Kennedy Krieger Institute, Johns Hopkins University School of Medicine , Baltimore, MD , USA
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26
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Tao C, Nichols TE, Hua X, Ching CRK, Rolls ET, Thompson PM, Feng J. Generalized reduced rank latent factor regression for high dimensional tensor fields, and neuroimaging-genetic applications. Neuroimage 2016; 144:35-57. [PMID: 27666385 DOI: 10.1016/j.neuroimage.2016.08.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Revised: 08/01/2016] [Accepted: 08/14/2016] [Indexed: 11/18/2022] Open
Abstract
We propose a generalized reduced rank latent factor regression model (GRRLF) for the analysis of tensor field responses and high dimensional covariates. The model is motivated by the need from imaging-genetic studies to identify genetic variants that are associated with brain imaging phenotypes, often in the form of high dimensional tensor fields. GRRLF identifies from the structure in the data the effective dimensionality of the data, and then jointly performs dimension reduction of the covariates, dynamic identification of latent factors, and nonparametric estimation of both covariate and latent response fields. After accounting for the latent and covariate effects, GRLLF performs a nonparametric test on the remaining factor of interest. GRRLF provides a better factorization of the signals compared with common solutions, and is less susceptible to overfitting because it exploits the effective dimensionality. The generality and the flexibility of GRRLF also allow various statistical models to be handled in a unified framework and solutions can be efficiently computed. Within the field of neuroimaging, it improves the sensitivity for weak signals and is a promising alternative to existing approaches. The operation of the framework is demonstrated with both synthetic datasets and a real-world neuroimaging example in which the effects of a set of genes on the structure of the brain at the voxel level were measured, and the results compared favorably with those from existing approaches.
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Affiliation(s)
- Chenyang Tao
- Centre for Computational Systems Biology and School of Mathematical Sciences, Fudan University, Shanghai, PR China; Department of Computer Science, Warwick University, Coventry, UK
| | | | - Xue Hua
- Imaging Genetics Center, Institute for Neuroimaging & Informatics, University of Southern California, Los Angeles, CA, USA
| | - Christopher R K Ching
- Imaging Genetics Center, Institute for Neuroimaging & Informatics, University of Southern California, Los Angeles, CA, USA; Interdepartmental Neuroscience Graduate Program, UCLA School of Medicine, Los Angeles, CA, USA
| | - Edmund T Rolls
- Department of Computer Science, Warwick University, Coventry, UK; Oxford Centre for Computational Neuroscience, Oxford, UK
| | - Paul M Thompson
- Imaging Genetics Center, Institute for Neuroimaging & Informatics, University of Southern California, Los Angeles, CA, USA; Departments of Neurology, Psychiatry, Radiology, Engineering, Pediatrics, and Ophthalmology, USC, Los Angeles, CA, USA
| | - Jianfeng Feng
- Centre for Computational Systems Biology and School of Mathematical Sciences, Fudan University, Shanghai, PR China; Department of Computer Science, Warwick University, Coventry, UK; School of Life Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200433, PR China.
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27
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Cao Y, Sarria I, Fehlhaber KE, Kamasawa N, Orlandi C, James KN, Hazen JL, Gardner MR, Farzan M, Lee A, Baker S, Baldwin K, Sampath AP, Martemyanov KA. Mechanism for Selective Synaptic Wiring of Rod Photoreceptors into the Retinal Circuitry and Its Role in Vision. Neuron 2015; 87:1248-1260. [PMID: 26402607 PMCID: PMC4583715 DOI: 10.1016/j.neuron.2015.09.002] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Revised: 08/11/2015] [Accepted: 08/31/2015] [Indexed: 01/06/2023]
Abstract
In the retina, rod and cone photoreceptors form distinct connections with different classes of downstream bipolar cells. However, the molecular mechanisms responsible for their selective connectivity are unknown. Here we identify a cell-adhesion protein, ELFN1, to be essential for the formation of synapses between rods and rod ON-bipolar cells in the primary rod pathway. ELFN1 is expressed selectively in rods where it is targeted to the axonal terminals by the synaptic release machinery. At the synapse, ELFN1 binds in trans to mGluR6, the postsynaptic receptor on rod ON-bipolar cells. Elimination of ELFN1 in mice prevents the formation of synaptic contacts involving rods, but not cones, allowing a dissection of the contributions of primary and secondary rod pathways to retinal circuit function and vision. We conclude that ELFN1 is necessary for the selective wiring of rods into the primary rod pathway and is required for high sensitivity of vision.
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Affiliation(s)
- Yan Cao
- Department of Neuroscience, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Ignacio Sarria
- Department of Neuroscience, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Katherine E Fehlhaber
- Jules Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, 100 Stein Plaza, Los Angeles, CA 90095, USA
| | - Naomi Kamasawa
- Electron Microscopy Core Facility, Max Planck Florida Institute, 1 Max Planck Way, Jupiter, FL 33458, USA
| | - Cesare Orlandi
- Department of Neuroscience, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Kiely N James
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92121, USA
| | - Jennifer L Hazen
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92121, USA
| | - Matthew R Gardner
- Department of Infectious Disease, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Michael Farzan
- Department of Infectious Disease, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Amy Lee
- Department of Molecular Physiology and Biophysics, University of Iowa, 51 Newton Road, Iowa City, IA 52242, USA
| | - Sheila Baker
- Department of Biochemistry, University of Iowa, 51 Newton Road, Iowa City, IA 52242, USA
| | - Kristin Baldwin
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92121, USA
| | - Alapakkam P Sampath
- Jules Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, 100 Stein Plaza, Los Angeles, CA 90095, USA
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA.
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28
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deCarvalho TN, Subedi A, Rock J, Harfe BD, Thisse C, Thisse B, Halpern ME, Hong E. Neurotransmitter map of the asymmetric dorsal habenular nuclei of zebrafish. Genesis 2014; 52:636-55. [PMID: 24753112 DOI: 10.1002/dvg.22785] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 04/16/2014] [Accepted: 04/18/2014] [Indexed: 12/11/2022]
Abstract
The role of the habenular nuclei in modulating fear and reward pathways has sparked a renewed interest in this conserved forebrain region. The bilaterally paired habenular nuclei, each consisting of a medial/dorsal and lateral/ventral nucleus, can be further divided into discrete subdomains whose neuronal populations, precise connectivity, and specific functions are not well understood. An added complexity is that the left and right habenulae show pronounced morphological differences in many non-mammalian species. Notably, the dorsal habenulae of larval zebrafish provide a vertebrate genetic model to probe the development and functional significance of brain asymmetry. Previous reports have described a number of genes that are expressed in the zebrafish habenulae, either in bilaterally symmetric patterns or more extensively on one side of the brain than the other. The goal of our study was to generate a comprehensive map of the zebrafish dorsal habenular nuclei, by delineating the relationship between gene expression domains, comparing the extent of left-right asymmetry at larval and adult stages, and identifying potentially functional subnuclear regions as defined by neurotransmitter phenotype. Although many aspects of habenular organization appear conserved with rodents, the zebrafish habenulae also possess unique properties that may underlie lateralization of their functions.
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Affiliation(s)
- Tagide N deCarvalho
- Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland
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