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Lim-Kian-Siang G, Izawa-Ishiguro AR, Rao Y. Neurexin-1-dependent circuit activity is required for the maintenance of photoreceptor subtype identity in Drosophila. Mol Brain 2024; 17:2. [PMID: 38167109 PMCID: PMC10759516 DOI: 10.1186/s13041-023-01073-3] [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: 10/11/2023] [Accepted: 12/18/2023] [Indexed: 01/05/2024] Open
Abstract
In the human and Drosophila color vision system, each photoreceptor neuron (cone cell in humans and R7/R8 photoreceptor cell in Drosophila) makes a stochastic decision to express a single photopigment of the same family with the exclusion of the others. While recent studies have begun to reveal the mechanisms that specify the generation of cone subtypes during development in mammals, nothing is known about how the mosaic of mutually exclusive cone subtypes is maintained in the mammalian retina. In Drosophila, recent work has led to the identification of several intrinsic factors that maintain the identity of R8 photoreceptor subtypes in adults. Whether and how extrinsic mechanisms are involved, however, remain unknown. In this study, we present evidence that supports that the Drosophila transsynaptic adhesion molecule Neurexin 1 (Dnrx-1) is required non-cell autonomously in R8p subtypes for the maintenance of R8y subtype identity. Silencing the activity of R8p subtypes caused a phenotype identical to that in dnrx-1 mutants. These results support a novel role for Nrx-1-dependent circuit activity in mediating the communication between R8 photoreceptor subtypes for maintaining the subtype identity in the retina.
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Affiliation(s)
- Gabrielle Lim-Kian-Siang
- McGill Centre for Research in Neuroscience, Montreal, Canada
- Integrated Program in Neuroscience, McGill University Health Centre, 1650 Cedar Avenue, Montreal, QC, H3G 1A4, Canada
| | - Arianna R Izawa-Ishiguro
- McGill Centre for Research in Neuroscience, Montreal, Canada
- Integrated Program in Neuroscience, McGill University Health Centre, 1650 Cedar Avenue, Montreal, QC, H3G 1A4, Canada
| | - Yong Rao
- McGill Centre for Research in Neuroscience, Montreal, Canada.
- Department of Neurology and Neurosurgery, Montreal, Canada.
- Integrated Program in Neuroscience, McGill University Health Centre, 1650 Cedar Avenue, Montreal, QC, H3G 1A4, Canada.
- Centre for Research in Neuroscience, McGill University Health Centre, Room L7-136, 1650 Cedar Avenue, Montreal, QC, H3G 1A4, Canada.
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2
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Oleari R, Lettieri A, Manzini S, Paganoni A, André V, Grazioli P, Busnelli M, Duminuco P, Vitobello A, Philippe C, Bizaoui V, Storr HL, Amoruso F, Memi F, Vezzoli V, Massa V, Scheiffele P, Howard SR, Cariboni A. Autism-linked NLGN3 is a key regulator of gonadotropin-releasing hormone deficiency. Dis Model Mech 2023; 16:dmm049996. [PMID: 36810932 PMCID: PMC10110398 DOI: 10.1242/dmm.049996] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 01/24/2023] [Indexed: 02/24/2023] Open
Abstract
Gonadotropin-releasing hormone (GnRH) deficiency (GD) is a disorder characterized by absent or delayed puberty, with largely unknown genetic causes. The purpose of this study was to obtain and exploit gene expression profiles of GnRH neurons during development to unveil novel biological mechanisms and genetic determinants underlying GD. Here, we combined bioinformatic analyses of immortalized and primary embryonic GnRH neuron transcriptomes with exome sequencing from GD patients to identify candidate genes implicated in the pathogenesis of GD. Among differentially expressed and filtered transcripts, we found loss-of-function (LoF) variants of the autism-linked neuroligin 3 (NLGN3) gene in two unrelated patients co-presenting with GD and neurodevelopmental traits. We demonstrated that NLGN3 is upregulated in maturing GnRH neurons and that NLGN3 wild-type, but not mutant, protein promotes neuritogenesis when overexpressed in developing GnRH cells. Our data represent proof of principle that this complementary approach can identify new candidate GD genes and demonstrate that LoF NLGN3 variants can contribute to GD. This novel genotype-phenotype correlation implies common genetic mechanisms underlying neurodevelopmental disorders, such as GD and autistic spectrum disorder.
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Affiliation(s)
- Roberto Oleari
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan 20133, Italy
| | - Antonella Lettieri
- CRC Aldo Ravelli for Neurotechnology and Experimental Brain Therapeutics, Department of Health Sciences, University of Milan, Milan 20142, Italy
- Department of Health Sciences, University of Milan, Milan 20142, Italy
| | - Stefano Manzini
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan 20133, Italy
| | - Alyssa Paganoni
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan 20133, Italy
| | - Valentina André
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan 20133, Italy
| | - Paolo Grazioli
- Department of Health Sciences, University of Milan, Milan 20142, Italy
| | - Marco Busnelli
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan 20133, Italy
| | - Paolo Duminuco
- Laboratory of Endocrine and Metabolic Research, IRCCS Istituto Auxologico Italiano, Cusano Milanino 20095, Italy
| | - Antonio Vitobello
- Unité Fonctionnelle Innovation en Diagnostic Génomique des Maladies Rares, Fédération Hospitalo-Universitaire (FHU) TRANSLAD, CHU Dijon Bourgogne, Dijon 21079, France
- INSERM UMR 1231 GAD (Génétique des Anomalies du Développement), Université de Bourgogne, Dijon 21070, France
| | - Christophe Philippe
- Unité Fonctionnelle Innovation en Diagnostic Génomique des Maladies Rares, Fédération Hospitalo-Universitaire (FHU) TRANSLAD, CHU Dijon Bourgogne, Dijon 21079, France
- INSERM UMR 1231 GAD (Génétique des Anomalies du Développement), Université de Bourgogne, Dijon 21070, France
| | - Varoona Bizaoui
- Genetics and Neurodevelopment, Centre Hospitalier de l'Estran, Pontorson 50170, France
| | - Helen L. Storr
- Centre for Endocrinology William Harvey Research Institute Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
- Royal London Children's Hospital, Barts Health NHS Trust, London E1 1BB, UK
| | - Federica Amoruso
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan 20133, Italy
| | - Fani Memi
- Wellcome-MRC Cambridge Stem Cell Institute, Jeffrey Cheah Biomedical Centre, Cambridge CB2 0AW, UK
| | - Valeria Vezzoli
- Laboratory of Endocrine and Metabolic Research, IRCCS Istituto Auxologico Italiano, Cusano Milanino 20095, Italy
| | - Valentina Massa
- CRC Aldo Ravelli for Neurotechnology and Experimental Brain Therapeutics, Department of Health Sciences, University of Milan, Milan 20142, Italy
- Department of Health Sciences, University of Milan, Milan 20142, Italy
| | | | - Sasha R. Howard
- Centre for Endocrinology William Harvey Research Institute Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
- Royal London Children's Hospital, Barts Health NHS Trust, London E1 1BB, UK
| | - Anna Cariboni
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan 20133, Italy
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3
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Gatford NJF, Deans PJM, Duarte RRR, Chennell G, Sellers KJ, Raval P, Srivastava DP. Neuroligin-3 and neuroligin-4X form nanoscopic clusters and regulate growth cone organization and size. Hum Mol Genet 2022; 31:674-691. [PMID: 34542148 PMCID: PMC8895740 DOI: 10.1093/hmg/ddab277] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 08/25/2021] [Accepted: 09/13/2021] [Indexed: 12/01/2022] Open
Abstract
The cell-adhesion proteins neuroligin-3 and neuroligin-4X (NLGN3/4X) have well described roles in synapse formation. NLGN3/4X are also expressed highly during neurodevelopment. However, the role these proteins play during this period is unknown. Here we show that NLGN3/4X localized to the leading edge of growth cones where it promoted neuritogenesis in immature human neurons. Super-resolution microscopy revealed that NLGN3/4X clustering induced growth cone enlargement and influenced actin filament organization. Critically, these morphological effects were not induced by autism spectrum disorder (ASD)-associated NLGN3/4X variants. Finally, actin regulators p21-activated kinase 1 and cofilin were found to be activated by NLGN3/4X and involved in mediating the effects of these adhesion proteins on actin filaments, growth cones and neuritogenesis. These data reveal a novel role for NLGN3 and NLGN4X in the development of neuronal architecture, which may be altered in the presence of ASD-associated variants.
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Affiliation(s)
- Nicholas J F Gatford
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology, & Neuroscience, King's College London, London, UK
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - P J Michael Deans
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology, & Neuroscience, King's College London, London, UK
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Rodrigo R R Duarte
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology, & Neuroscience, King's College London, London, UK
| | - George Chennell
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology, & Neuroscience, King's College London, London, UK
| | - Katherine J Sellers
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology, & Neuroscience, King's College London, London, UK
| | - Pooja Raval
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology, & Neuroscience, King's College London, London, UK
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Deepak P Srivastava
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology, & Neuroscience, King's College London, London, UK
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
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Martinez-Moreno CG, Epardo D, Balderas-Márquez JE, Fleming T, Carranza M, Luna M, Harvey S, Arámburo C. Regenerative Effect of Growth Hormone (GH) in the Retina after Kainic Acid Excitotoxic Damage. Int J Mol Sci 2019; 20:E4433. [PMID: 31509934 PMCID: PMC6770150 DOI: 10.3390/ijms20184433] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 09/03/2019] [Accepted: 09/04/2019] [Indexed: 02/06/2023] Open
Abstract
In addition to its role as an endocrine messenger, growth hormone (GH) also acts as a neurotrophic factor in the central nervous system (CNS), whose effects are involved in neuroprotection, axonal growth, and synaptogenic modulation. An increasing amount of clinical evidence shows a beneficial effect of GH treatment in patients with brain trauma, stroke, spinal cord injury, impaired cognitive function, and neurodegenerative processes. In response to injury, Müller cells transdifferentiate into neural progenitors and proliferate, which constitutes an early regenerative process in the chicken retina. In this work, we studied the long-term protective effect of GH after causing severe excitotoxic damage in the retina. Thus, an acute neural injury was induced via the intravitreal injection of kainic acid (KA, 20 µg), which was followed by chronic administration of GH (10 injections [300 ng] over 21 days). Damage provoked a severe disruption of several retinal layers. However, in KA-damaged retinas treated with GH, we observed a significant restoration of the inner plexiform layer (IPL, 2.4-fold) and inner nuclear layer (INL, 1.5-fold) thickness and a general improvement of the retinal structure. In addition, we also observed an increase in the expression of several genes involved in important regenerative pathways, including: synaptogenic markers (DLG1, NRXN1, GAP43); glutamate receptor subunits (NR1 and GRIK4); pro-survival factors (BDNF, Bcl-2 and TNF-R2); and Notch signaling proteins (Notch1 and Hes5). Interestingly, Müller cell transdifferentiation markers (Sox2 and FGF2) were upregulated by this long-term chronic GH treatment. These results are consistent with a significant increase in the number of BrdU-positive cells observed in the KA-damaged retina, which was induced by GH administration. Our data suggest that GH is able to facilitate the early proliferative response of the injured retina and enhance the regeneration of neurite interconnections.
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Affiliation(s)
- Carlos G Martinez-Moreno
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus Juriquilla, Universidad Nacional Autónoma de México, Querétaro, Qro., 76230, Mexico.
| | - David Epardo
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus Juriquilla, Universidad Nacional Autónoma de México, Querétaro, Qro., 76230, Mexico
| | - Jerusa E Balderas-Márquez
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus Juriquilla, Universidad Nacional Autónoma de México, Querétaro, Qro., 76230, Mexico.
| | - Thomas Fleming
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus Juriquilla, Universidad Nacional Autónoma de México, Querétaro, Qro., 76230, Mexico.
| | - Martha Carranza
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus Juriquilla, Universidad Nacional Autónoma de México, Querétaro, Qro., 76230, Mexico.
| | - Maricela Luna
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus Juriquilla, Universidad Nacional Autónoma de México, Querétaro, Qro., 76230, Mexico.
| | - Steve Harvey
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada.
| | - Carlos Arámburo
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus Juriquilla, Universidad Nacional Autónoma de México, Querétaro, Qro., 76230, Mexico.
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5
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Tian M, Zhou Y, Qiu L, Liu F, Jin L, Li W, Zhang L. NL1 expression level in Nrx1β and the excitability of PV interneurons in mice with POCD. Exp Ther Med 2019; 17:3117-3123. [PMID: 30936983 PMCID: PMC6434254 DOI: 10.3892/etm.2019.7322] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 01/10/2019] [Indexed: 01/03/2023] Open
Abstract
Effects of NL1 on the expression level of neurexin-1β (Nrx1β) and the excitability of parvalbumin (PV) interneurons in mice with postoperative cognitive dysfunction (POCD) were explored. Eighty 10-month-old C57BL/6 male mice were randomly divided into four groups: control group, control+empty vector group (Control+EV), anesthesia surgery+empty vector group (POCD+EV group) and anesthesia+NL1 overexpression group (POCD+NL1 group), (n=20 per group). The behavioral differences of mice in the four groups were analyzed by means of open field test and fear conditioning test. The expression levels of NL1, PV and Nrx1β were detected by western blot analysis, and the binding between NL1 and Nrx1β was determined by co-immunoprecipitation. The expression level of postsynaptic density protein 95 (PSD95) in hippocampus and changes in the excitability of PV interneurons were further detected. Control and Control+EV groups had no significant difference in each index (P>0.05). Compared with Control+EV group, the percentage of cued freezing time in POCD+EV group decreased significantly, while percentage of cued freezing time was significantly increased in POCD+NL1 group and POCD+EV group (P<0.01). The differences in freezing time were not statistically significant among the 4 groups in the tone-related fear test (P>0.05). Then NL1 was overexpressed in mice with POCD, the protein levels of PV, Nrx1β and PSD95 were subsequently increased, and the interaction between NL1 and Nrx1β protein was enhanced, dramatically increasing the excitability of PV interneurons. The overexpression of NL1 can upregulate the expression levels of PV, Nrx1β and PSD95 in mice with POCD, enhance the interaction between NL1 and Nrx1β and further increase the excitability of PV interneurons, thus restoring the hippocampus-dependent memorial and cognitive impairment in POCD.
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Affiliation(s)
- Mi Tian
- Department of Anesthesiology, Nanjing General Hospital, Nanjing, Jiangsu 210000, P.R. China
| | - Yuan Zhou
- Department of Neurosurgery, Nanjing General Hospital, Nanjing, Jiangsu 210000, P.R. China
| | - Lili Qiu
- Department of Anesthesiology, Zhongda Hospital Southeast University, Nanjing, Jiangsu 210000, P.R. China
| | - Fangfang Liu
- Department of Anesthesiology, Nanjing General Hospital, Nanjing, Jiangsu 210000, P.R. China
| | - Li Jin
- Department of Anesthesiology, Nanjing General Hospital, Nanjing, Jiangsu 210000, P.R. China
| | - Weiyan Li
- Department of Anesthesiology, Nanjing General Hospital, Nanjing, Jiangsu 210000, P.R. China
| | - Lidong Zhang
- Department of Anesthesiology, Nanjing General Hospital, Nanjing, Jiangsu 210000, P.R. China
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6
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Abstract
Neurexin 1 (NRXN1), a presynaptic cell adhesion molecule, is implicated in several neurodevelopmental disorders characterized by synaptic dysfunction including autism, intellectual disability and schizophrenia. To gain insight into NRXN1's involvement in human cortical development we used quantitative real-time PCR to examine the expression trajectories of NRXN1, and its predominant isoforms, NRXN1-α and NRXN1-β, in prefrontal cortex from fetal stages to aging. In addition, we investigated whether prefrontal cortical expression levels of NRXN1 transcripts are altered in schizophrenia or bipolar disorder in comparison with non-psychiatric control subjects. We observed that all three NRXN1 transcripts were highly expressed during human fetal cortical development, markedly increasing with gestational age. In the postnatal dorsolateral prefrontal cortex, expression levels were negatively correlated with age, peaking at birth until ~3 years of age, after which levels declined markedly to be stable across the lifespan. NRXN1-β expression was modestly but significantly elevated in the brains of patients with schizophrenia compared with non-psychiatric controls, whereas NRXN1-α expression was increased in bipolar disorder. These data provide novel evidence that NRXN1 expression is highest in human dorsolateral prefrontal cortex during critical developmental windows relevant to the onset and diagnosis of a range of neurodevelopmental disorders, and that NRXN1 expression may be differentially altered in neuropsychiatric disorders.
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7
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The interplay between synaptic activity and neuroligin function in the CNS. BIOMED RESEARCH INTERNATIONAL 2015; 2015:498957. [PMID: 25839034 PMCID: PMC4369883 DOI: 10.1155/2015/498957] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 02/12/2015] [Accepted: 02/23/2015] [Indexed: 11/24/2022]
Abstract
Neuroligins (NLs) are postsynaptic transmembrane cell-adhesion proteins that play a key role in the regulation of excitatory and inhibitory synapses. Previous in vitro and in vivo studies have suggested that NLs contribute to synapse formation and synaptic transmission. Consistent with their localization, NL1 and NL3 selectively affect excitatory synapses, whereas NL2 specifically affects inhibitory synapses. Deletions or mutations in NL genes have been found in patients with autism spectrum disorders or mental retardations, and mice harboring the reported NL deletions or mutations exhibit autism-related behaviors and synapse dysfunction. Conversely, synaptic activity can regulate the phosphorylation, expression, and cleavage of NLs, which, in turn, can influence synaptic activity. Thus, in clinical research, identifying the relationship between NLs and synapse function is critical. In this review, we primarily discuss how NLs and synaptic activity influence each other.
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Tian Y, Li T, Sun M, Wan D, Li Q, Li P, Zhang Z, Han J, Xie W. Neurexin Regulates Visual Function via Mediating Retinoid Transport to Promote Rhodopsin Maturation. Neuron 2013; 77:311-22. [DOI: 10.1016/j.neuron.2012.11.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/07/2012] [Indexed: 12/22/2022]
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Wahlin KJ, Hackler L, Adler R, Zack DJ. Alternative splicing of neuroligin and its protein distribution in the outer plexiform layer of the chicken retina. J Comp Neurol 2011; 518:4938-62. [PMID: 21031560 DOI: 10.1002/cne.22499] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Although synaptogenesis within the retina is obviously essential for vision, mechanisms responsible for the initiation and maintenance of retinal synapses are poorly understood. In addition to its scientific interest, understanding retinal synapse formation is becoming clinically relevant with ongoing efforts to develop transplantation-based approaches for the treatment of retinal degenerative disease. To extend our understanding, we have focused on the chick model system and have studied the neuroligin family of neuronal adhesion factors that has been shown to participate in synapse assembly in the brain. We identified chicken orthologs of neuroligins 1, -3, and -4, but could find no evidence of neuroligin 2. We investigated temporal and spatial patterns of mRNA and protein expression during development using standard polymerase chain reaction (RT-PCR), quantitative PCR (QPCR), laser-capture microdissection (LCM), and confocal microscopy. At the mRNA level, neuroligins were detected at the earliest period tested, embryonic day (ED)5, which precedes the period of inner retina synaptogenesis. Significant alternative splicing was observed through development. While neuroligin gene products were generally detected in the inner retina, low levels of neuroligin 1 mRNA were also detected in the photoreceptor layer. Neuroligin 3 and -4 transcripts, on the other hand, were only detected in the inner retina. At retinal synapses neuroligin 1 protein was detected in the inner plexiform layer, but its highest levels were detected in the outer plexiform layer on the tips of horizontal cell dendrites. This work lays the groundwork for future studies on the functional roles of the neuroligins within the retina.
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Affiliation(s)
- Karl J Wahlin
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
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Rissone A, Sangiorgio L, Monopoli M, Beltrame M, Zucchi I, Bussolino F, Arese M, Cotelli F. Characterization of the neuroligin gene family expression and evolution in zebrafish. Dev Dyn 2010; 239:688-702. [PMID: 20034102 DOI: 10.1002/dvdy.22196] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neuroligins constitute a family of transmembrane proteins localized at the postsynaptic side of both excitatory and inhibitory synapses of the central nervous system. They are involved in synaptic function and maturation and recent studies have linked mutations in specific human Neuroligins to mental retardation and autism. We isolated the human Neuroligin homologs in Danio rerio. Next, we studied their gene structures and we reconstructed the evolution of the Neuroligin genes across vertebrate phyla. Using reverse-transcriptase polymerase chain reaction, we analyzed the expression and alternative splicing pattern of each gene during zebrafish embryonic development and in different adult organs. By in situ hybridization, we analyzed the temporal and spatial expression pattern during embryonic development and larval stages and we found that zebrafish Neuroligins are expressed throughout the nervous system. Globally, our results indicate that, during evolution, specific subfunctionalization events occurred within paralogous members of this gene family in zebrafish.
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Affiliation(s)
- Alberto Rissone
- Department of Oncological Sciences, University of Torino School of Medicine, Candiolo, Italy.
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11
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Lui L, Levinson JN, Noël G, Handrigan GR, Richman JM, El-Husseini A, Moukhles H. Synaptic localization of neuroligin 2 in the rodent retina: comparative study with the dystroglycan-containing complex. J Neurosci Res 2010; 88:837-49. [PMID: 19859968 DOI: 10.1002/jnr.22258] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Several recent studies have shown that neuroligin 2 (NL2), a component of the cell adhesion neurexins-neuroligins complex, is localized postsynaptically at hippocampal and other inhibitory synapses throughout the brain. Other studies have shown that components of the dystroglycan complex are also localized at a subset of inhibitory synapses and are coexpressed with NL2 in brain. These data prompted us to undertake a comparative study between the localization of NL2 and the dystroglycan complex in the rodent retina. First, we determined that NL2 mRNA is expressed both in the inner and in the outer nuclear layers. Second, we found that NL2 is localized both in the inner and in the outer synaptic plexiform layers. In the latter, the horseshoe-shaped pattern of NL2 and its extensive colocalization with RIM2, a component of the presynaptic active zone at ribbon synapses, argue that NL2 is localized presynaptically at photoreceptor terminals. Third, comparison of NL2 and the dystroglycan complex distribution patterns reveals that, despite their coexpression in the outer plexiform layer, they are spatially segregated within distinct domains of the photoreceptor terminals, where NL2 is selectively associated with the active zone and the dystroglycan complex is distally distributed in the lateral regions. Finally, we report that the dystroglycan deficiency in the mdx(3cv) mouse does not alter NL2 localization in the outer plexiform layer. These data show that the NL2- and dystroglycan-containing complexes are differentially localized in the presynaptic photoreceptor terminals and suggest that they may serve distinct functions in retina.
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Affiliation(s)
- Leona Lui
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
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