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Longhena F, Faustini G, Brembati V, Pizzi M, Benfenati F, Bellucci A. An updated reappraisal of synapsins: structure, function and role in neurological and psychiatric disorders. Neurosci Biobehav Rev 2021; 130:33-60. [PMID: 34407457 DOI: 10.1016/j.neubiorev.2021.08.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 07/29/2021] [Accepted: 08/09/2021] [Indexed: 01/02/2023]
Abstract
Synapsins (Syns) are phosphoproteins strongly involved in neuronal development and neurotransmitter release. Three distinct genes SYN1, SYN2 and SYN3, with elevated evolutionary conservation, have been described to encode for Synapsin I, Synapsin II and Synapsin III, respectively. Syns display a series of common features, but also exhibit distinctive localization, expression pattern, post-translational modifications (PTM). These characteristics enable their interaction with other synaptic proteins, membranes and cytoskeletal components, which is essential for the proper execution of their multiple functions in neuronal cells. These include the control of synapse formation and growth, neuron maturation and renewal, as well as synaptic vesicle mobilization, docking, fusion, recycling. Perturbations in the balanced expression of Syns, alterations of their PTM, mutations and polymorphisms of their encoding genes induce severe dysregulations in brain networks functions leading to the onset of psychiatric or neurological disorders. This review presents what we have learned since the discovery of Syn I in 1977, providing the state of the art on Syns structure, function, physiology and involvement in central nervous system disorders.
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Affiliation(s)
- Francesca Longhena
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
| | - Gaia Faustini
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
| | - Viviana Brembati
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
| | - Marina Pizzi
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
| | - Fabio Benfenati
- Italian Institute of Technology, Via Morego 30, Genova, Italy; IRCSS Policlinico San Martino Hospital, Largo Rosanna Benzi 10, 16132, Genova, Italy.
| | - Arianna Bellucci
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy; Laboratory for Preventive and Personalized Medicine, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
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Genetic variation associated with the occurrence and progression of neurological disorders. Neurotoxicology 2017; 61:243-264. [DOI: 10.1016/j.neuro.2016.09.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 09/23/2016] [Indexed: 02/08/2023]
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Walsh S, Donnan J, Fortin Y, Sikora L, Morrissey A, Collins K, MacDonald D. A systematic review of the risks factors associated with the onset and natural progression of epilepsy. Neurotoxicology 2017; 61:64-77. [DOI: 10.1016/j.neuro.2016.03.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 03/14/2016] [Indexed: 01/08/2023]
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Haerian BS, Sha'ari HM, Fong CY, Tan HJ, Wong SW, Ong LC, Raymond AA, Tan CT, Mohamed Z. Contribution of TIMP4 rs3755724 polymorphism to susceptibility to focal epilepsy in Malaysian Chinese. J Neuroimmunol 2015; 278:137-43. [PMID: 25595263 DOI: 10.1016/j.jneuroim.2014.12.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Revised: 12/13/2014] [Accepted: 12/17/2014] [Indexed: 11/20/2022]
Abstract
Neuroinflammation can damage the brain and plays a critical role in the pathophysiology of epilepsy. Tissue inhibitor of metalloproteinase 4 (TIMP4) is an inflammation-induced apoptosis and matrix turnover factor involved in several neuronal disorders and inflammatory diseases. Evidence has shown linkage disequilibrium between rs3755724 (-55C/T) of this gene with synapsin 2 (SYN2) rs3773364 and peroxisome proliferator-activated G receptor (PPARG) rs2920502 loci, which contribute to epilepsy in Caucasians. The aim of this study was to examine the association of these loci alone or their haplotypes with the risk of epilepsy in the Malaysian population. Genomic DNA of 1241 Malaysian Chinese, Indian, and Malay subjects (670 patients with epilepsy and 571 healthy individuals) was genotyped for the candidate loci by using the Sequenom MassArray method. Allele and genotype association of rs3755724 with susceptibility to epilepsy was significant in the Malaysian Chinese with focal epilepsy under codominant and dominant models (C vs. T: 1.5 (1.1-2.0), p=0.02; CT vs. TT: 1.8 (1.2-2.8), p=0.007 and 1.8 (1.2-2.7), p=0.006, respectively). The T allele and the TT genotype were more common in patients than in controls. No significant association was found between rs2920502 and rs3773364-rs3755724-rs2920502 haplotypes for susceptibility to epilepsy in each ethnicity. This study provides evidence that the promoter TIMP4 rs3755724 is a new focal epilepsy susceptibility variant that is plausibly involved in inflammation-induced seizures in Malaysian Chinese.
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Affiliation(s)
- Batoul Sadat Haerian
- Pharmacogenomics Laboratory, Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
| | - Hidayati Mohd Sha'ari
- Pharmacogenomics Laboratory, Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Choong Yi Fong
- Division of Paediatrics Neurology, Department of Paediatrics, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Hui Jan Tan
- Division of Neurology, Department of Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Sau Wei Wong
- Division of Paediatrics Neurology, Department of Paediatrics, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Lai Choo Ong
- Division of Paediatrics Neurology, Department of Paediatrics, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Azman Ali Raymond
- Division of Neurology, Department of Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Chong Tin Tan
- Division of Neurology, Department of Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Zahurin Mohamed
- Pharmacogenomics Laboratory, Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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Association of GABRA6 1519 T>C (rs3219151) and Synapsin II (rs37733634) gene polymorphisms with the development of idiopathic generalized epilepsy. Epilepsy Res 2014; 108:1267-73. [DOI: 10.1016/j.eplepsyres.2014.07.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 06/18/2014] [Accepted: 07/09/2014] [Indexed: 11/22/2022]
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Corradi A, Fadda M, Piton A, Patry L, Marte A, Rossi P, Cadieux-Dion M, Gauthier J, Lapointe L, Mottron L, Valtorta F, Rouleau GA, Fassio A, Benfenati F, Cossette P. SYN2 is an autism predisposing gene: loss-of-function mutations alter synaptic vesicle cycling and axon outgrowth. Hum Mol Genet 2013; 23:90-103. [PMID: 23956174 PMCID: PMC3857945 DOI: 10.1093/hmg/ddt401] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
An increasing number of genes predisposing to autism spectrum disorders (ASDs) has been identified, many of which are implicated in synaptic function. This 'synaptic autism pathway' notably includes disruption of SYN1 that is associated with epilepsy, autism and abnormal behavior in both human and mice models. Synapsins constitute a multigene family of neuron-specific phosphoproteins (SYN1-3) present in the majority of synapses where they are implicated in the regulation of neurotransmitter release and synaptogenesis. Synapsins I and II, the major Syn isoforms in the adult brain, display partially overlapping functions and defects in both isoforms are associated with epilepsy and autistic-like behavior in mice. In this study, we show that nonsense (A94fs199X) and missense (Y236S and G464R) mutations in SYN2 are associated with ASD in humans. The phenotype is apparent in males. Female carriers of SYN2 mutations are unaffected, suggesting that SYN2 is another example of autosomal sex-limited expression in ASD. When expressed in SYN2 knockout neurons, wild-type human Syn II fully rescues the SYN2 knockout phenotype, whereas the nonsense mutant is not expressed and the missense mutants are virtually unable to modify the SYN2 knockout phenotype. These results identify for the first time SYN2 as a novel predisposing gene for ASD and strengthen the hypothesis that a disturbance of synaptic homeostasis underlies ASD.
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Affiliation(s)
- Anna Corradi
- Department of Experimental Medicine, University of Genova, Viale Benedetto XV 3, Genova 16132, Italy
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Etholm L, Bahonjic E, Walaas SI, Kao HT, Heggelund P. Neuroethologically delineated differences in the seizure behavior of synapsin 1 and synapsin 2 knock-out mice. Epilepsy Res 2012; 99:252-9. [PMID: 22236379 DOI: 10.1016/j.eplepsyres.2011.12.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 11/25/2011] [Accepted: 12/01/2011] [Indexed: 10/14/2022]
Abstract
The highly homologous nerve terminal phosphoproteins synapsin I and synapsin II have been linked to the pathogenesis of epilepsy through associations between synapsin gene mutations and epileptic disease in humans and to the observation of handling induced seizures in mice genetically depleted of one or both of these proteins. Whereas seizure behavior in mice lacking both synapsin I and synapsin II is well characterized, the seizure behavior in mice lacking either is less well studied. Through so called neuroethologically based analyses of fully established seizure behavior in Synapsin 1 and 2 knock-out mice (Syn1KO and Syn2KO mice) aged 4 1/2 months, this study reveals significant differences in the seizure behavior of the two genotypes: whereas Syn1KO mice show both partial and generalized forebrain seizure activity, Syn2KO mice show only fully generalized forebrain seizures. Analysis of seizure behavior at earlier stages shows that the mature seizure pattern in Syn2KO mice establishes rapidly from the age of ∼2 months, when Syn1KO partial seizures are rare, and Syn1KO generalized seizures are almost absent. The specific behavioral phenotypes of the two strains suggest that the slight differences in structure, function and expression of these highly related proteins could be important factors during seizure generating neural activity.
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Affiliation(s)
- Lars Etholm
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital - Rikshospitalet, Oslo, Norway.
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