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Wang M, Gu Y, Li Q, Feng B, Lv X, Zhang H, Kong Q, Dong Z, Tian X, Zhang Y. The Traf2 and NcK interacting kinase inhibitor NCB-0846 suppresses seizure activity involving the decrease of GRIA1. Genes Dis 2024; 11:100997. [PMID: 38292191 PMCID: PMC10826163 DOI: 10.1016/j.gendis.2023.03.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 03/09/2023] [Accepted: 03/29/2023] [Indexed: 02/01/2024] Open
Abstract
Epilepsy, one of the most common neurological disorders, is characterized by spontaneous recurrent seizures. Temporal lobe epilepsy (TLE) is one of the most common medically intractable seizure disorders. Traf2-and NcK-interacting kinase (TNIK) has recently attracted attention as a critical modulation target of many neurological and psychiatric disorders, but its role in epilepsy remains unclear. In this study, we hypothesized the involvement of TNIK in epilepsy and investigated TNIK expression in patients with intractable TLE and in a pilocarpine-induced rat model of epilepsy by western blotting, immunofluorescence, and immunohistochemistry. A pentylenetetrazole (PTZ)-induced epilepsy rat model was used to determine the effect of the TNIK inhibitor NCB-0846 on behavioral manifestations of epilepsy. Coimmunoprecipitation (Co-IP)/mass spectrometry (MS) was used to identify the potential mechanism. Through Co-IP, we detected and confirmed the main potential TNIK interactors. Subcellular fractionation was used to establish the effect of NCB-0846 on the expression of the main interactors in postsynaptic density (PSD) fractions. We found that TNIK was primarily located in neurons and decreased significantly in epilepsy model rats and TLE patients compared with controls. NCB-0846 delayed kindling progression and decreased seizure severity. Co-IP/MS identified 63 candidate TNIK interactors in rat hippocampi, notably CaMKII. Co-IP showed that TNIK might correlate with endogenous GRIA1, SYN2, PSD-95, CaMKIV, GABRG1, and GABRG2. In addition, the significant decrease in GRIA1 in hippocampal total lysate and PSDs after NCB-0846 treatment might help modify the progression of PTZ kindling. Our results suggest that TNIK contributes to epileptic pathology and is a potential antiepileptic drug target.
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Affiliation(s)
- Min Wang
- Department of Neurology, Affiliated Hospital of Jining Medical University, Jining, Shandong 272000, China
| | - Yixue Gu
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing 400016, China
| | - Qiubo Li
- Department of Pediatrics, Affiliated Hospital of Jining Medical University, Jining, Shandong 272000, China
| | - Bangzhe Feng
- Department of Neurology, Affiliated Hospital of Jining Medical University, Jining, Shandong 272000, China
| | - Xinke Lv
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing 400016, China
| | - Hao Zhang
- Department of Neurosurgery, Affiliated Hospital of Jining Medical University, Jining, Shandong 272000, China
| | - Qingxia Kong
- Department of Neurology, Affiliated Hospital of Jining Medical University, Jining, Shandong 272000, China
| | - Zhifang Dong
- Pediatric Research Institute, Ministry of Education Key Laboratory of Child Development and Disorders, National Clinical Research Center for Child Health and Disorders, Chongqing Key Laboratory of Translational Medical Research in Cognitive Development and Learning and Memory Disorders, Children's Hospital of Chongqing Medical University, Chongqing 400014, China
| | - Xin Tian
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing 400016, China
| | - Yanke Zhang
- Department of Neurology, Affiliated Hospital of Jining Medical University, Jining, Shandong 272000, China
- Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
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2
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Bernardin AA, Colombani S, Rousselot A, Andry V, Goumon Y, Delanoë-Ayari H, Pasqualin C, Brugg B, Jacotot ED, Pasquié JL, Lacampagne A, Meli AC. Impact of Neurons on Patient-Derived Cardiomyocytes Using Organ-On-A-Chip and iPSC Biotechnologies. Cells 2022; 11:cells11233764. [PMID: 36497024 PMCID: PMC9737466 DOI: 10.3390/cells11233764] [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: 10/18/2022] [Revised: 11/18/2022] [Accepted: 11/21/2022] [Indexed: 11/27/2022] Open
Abstract
In the heart, cardiac function is regulated by the autonomic nervous system (ANS) that extends through the myocardium and establishes junctions at the sinus node and ventricular levels. Thus, an increase or decrease in neuronal activity acutely affects myocardial function and chronically affects its structure through remodeling processes. The neuro-cardiac junction (NCJ), which is the major structure of this system, is poorly understood and only a few cell models allow us to study it. Here, we present an innovant neuro-cardiac organ-on-chip model to study this structure to better understand the mechanisms involved in the establishment of NCJ. To create such a system, we used microfluidic devices composed of two separate cell culture compartments interconnected by asymmetric microchannels. Rat PC12 cells were differentiated to recapitulate the characteristics of sympathetic neurons, and cultivated with cardiomyocytes derived from human induced pluripotent stem cells (hiPSC). We confirmed the presence of a specialized structure between the two cell types that allows neuromodulation and observed that the neuronal stimulation impacts the excitation-contraction coupling properties including the intracellular calcium handling. Finally, we also co-cultivated human neurons (hiPSC-NRs) with human cardiomyocytes (hiPSC-CMs), both obtained from the same hiPSC line. Hence, we have developed a neuro-cardiac compartmentalized in vitro model system that allows us to recapitulate the structural and functional properties of the neuro-cardiac junction and that can also be used to better understand the interaction between the heart and brain in humans, as well as to evaluate the impact of drugs on a reconstructed human neuro-cardiac system.
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Affiliation(s)
- Albin A. Bernardin
- PhyMedExp, University of Montpellier, Inserm, CNRS, 371 Avenue du Doyen G. Giraud, CEDEX 5, 34295 Montpellier, France
- MicroBrain Biotech S.A.S., 78160 Marly Le-Roi, France
| | - Sarah Colombani
- PhyMedExp, University of Montpellier, Inserm, CNRS, 371 Avenue du Doyen G. Giraud, CEDEX 5, 34295 Montpellier, France
| | - Antoine Rousselot
- MicroBrain Biotech S.A.S., 78160 Marly Le-Roi, France
- Université Paris-Saclay, CEA, CNRS, NIMBE, 91191 Gif-sur-Yvette, France
| | - Virginie Andry
- SMPMS-INCI, Mass Spectrometry Facilities of the CNRS UPR3212, CNRS UPR3212, Institut des Neu-Rosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique and University of Strasbourg, 68009 Strasbourg, France
| | - Yannick Goumon
- SMPMS-INCI, Mass Spectrometry Facilities of the CNRS UPR3212, CNRS UPR3212, Institut des Neu-Rosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique and University of Strasbourg, 68009 Strasbourg, France
| | - Hélène Delanoë-Ayari
- Claude Bernard University, Université de Lyon, Institut lumière matière, 69000 Lyon, France
| | - Côme Pasqualin
- Groupe Physiologie des Cellules Cardiaques et Vasculaires, Université de Tours, EA4245 Transplantation, Immunologie, Inflammation, 37000 Tours, France
| | - Bernard Brugg
- Sorbonne Université, Campus Pierre et Marie Curie, Institut de Biologie Paris-Seine, CNRS UMR 8256, INSERM U1164, F-75005 Paris, France
| | - Etienne D. Jacotot
- Sorbonne Université, Campus Pierre et Marie Curie, Institut de Biologie Paris-Seine, CNRS UMR 8256, INSERM U1164, F-75005 Paris, France
- The Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Columbia University, New York, NY 10032, USA
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Jean-Luc Pasquié
- PhyMedExp, University of Montpellier, Inserm, CNRS, 371 Avenue du Doyen G. Giraud, CEDEX 5, 34295 Montpellier, France
- Department of Cardiology, Montpellier University Hospital, 34295 Montpellier, France
| | - Alain Lacampagne
- PhyMedExp, University of Montpellier, Inserm, CNRS, 371 Avenue du Doyen G. Giraud, CEDEX 5, 34295 Montpellier, France
- Correspondence: (A.L.); (A.C.M.)
| | - Albano C. Meli
- PhyMedExp, University of Montpellier, Inserm, CNRS, 371 Avenue du Doyen G. Giraud, CEDEX 5, 34295 Montpellier, France
- Correspondence: (A.L.); (A.C.M.)
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Hendricks EL, Smith IR, Prates B, Barmaleki F, Liebl FLW. The CD63 homologs, Tsp42Ee and Tsp42Eg, restrict endocytosis and promote neurotransmission through differential regulation of synaptic vesicle pools. Front Cell Neurosci 2022; 16:957232. [PMID: 36072568 PMCID: PMC9441712 DOI: 10.3389/fncel.2022.957232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 08/04/2022] [Indexed: 11/30/2022] Open
Abstract
The Tetraspanin (Tsp), CD63, is a transmembrane component of late endosomes and facilitates vesicular trafficking through endosomal pathways. Despite being widely expressed in the human brain and localized to late endosomes, CD63's role in regulating endo- and exocytic cycling at the synapse has not been investigated. Synaptic vesicle pools are highly dynamic and disruptions in the mobilization and replenishment of these vesicle pools have adverse neuronal effects. We find that the CD63 homologs, Tsp42Ee and Tsp42Eg, are expressed at the Drosophila neuromuscular junction to regulate synaptic vesicle pools through both shared and unique mechanisms. Tsp42Ee and Tsp42Eg negatively regulate endocytosis and positively regulate neurotransmitter release. Both tsp mutants show impaired locomotion, reduced miniature endplate junctional current frequencies, and increased endocytosis. Expression of human CD63 in Drosophila neurons leads to impaired endocytosis suggesting the role of Tsps in endocytosis is conserved. We further show that Tsps influence the synaptic cytoskeleton and membrane composition by regulating Futsch loop formation and synaptic levels of SCAR and PI(4,5)P2. Finally, Tsp42Ee and Tsp42Eg influence the synaptic localization of several vesicle-associated proteins including Synapsin, Synaptotagmin, and Cysteine String Protein. Together, our results present a novel function for Tsps in the regulation of vesicle pools and provide insight into the molecular mechanisms of Tsp-related synaptic dysfunction.
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Affiliation(s)
| | | | | | | | - Faith L. W. Liebl
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL, United States
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4
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Zhi WJ, Qiao SM, Zou Y, Peng RY, Yan HT, Ma LZ, Dong J, Zhao L, Yao BW, Zhao XL, Feng XX, Hu XJ, Wang LF. Low p-SYN1 (Ser-553) Expression Leads to Abnormal Neurotransmitter Release of GABA Induced by Up-Regulated Cdk5 after Microwave Exposure: Insights on Protection and Treatment of Microwave-Induced Cognitive Dysfunction. Curr Issues Mol Biol 2021; 44:206-221. [PMID: 35723394 PMCID: PMC8929049 DOI: 10.3390/cimb44010015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 12/22/2021] [Accepted: 12/27/2021] [Indexed: 11/23/2022] Open
Abstract
With the wide application of microwave technology, concerns about its health impact have arisen. The signal transmission mode of the central nervous system and neurons make it particularly sensitive to electromagnetic exposure. It has been reported that abnormal release of amino acid neurotransmitters is mediated by alteration of p-SYN1 after microwave exposure, which results in cognitive dysfunction. As the phosphorylation of SYN1 is regulated by different kinases, in this study we explored the regulatory mechanisms of SYN1 fluctuations following microwave exposure and its subsequent effect on GABA release, aiming to provide clues on the mechanism of cognitive impairment caused by microwave exposure. In vivo studies with Timm and H&E staining were adopted and the results showed abnormality in synapse formation and neuronal structure, explaining the previously-described deficiency in cognitive ability caused by microwave exposure. The observed alterations in SYN1 level, combined with the results of earlier studies, indicate that SYN1 and its phosphorylation status (ser-553 and ser62/67) may play a role in the abnormal release of neurotransmitters. Thus, the role of Cdk5, the upstream kinase regulating the formation of p-SYN1 (ser-553), as well as that of MEK, the regulator of p-SYN1 (ser-62/67), were investigated both in vivo and in vitro. The results showed that Cdk5 was a negative regulator of p-SYN1 (ser-553) and that its up-regulation caused a decrease in GABA release by reducing p-SYN1 (ser-553). While further exploration still needed to elaborate the role of p-SYN1 (ser-62/67) for neurotransmitter release, MEK inhibition had was no impact on p-Erk or p-SYN1 (ser-62/67) after microwave exposure. In conclusion, the decrease of p-SYN1 (ser-553) may result in abnormalities in vesicular anchoring and GABA release, which is caused by increased Cdk5 regulated through Calpain-p25 pathway after 30 mW/cm2 microwave exposure. This study provided a potential new strategy for the prevention and treatment of microwave-induced cognitive dysfunction.
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Affiliation(s)
- Wei-Jia Zhi
- Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850, China; (W.-J.Z.); (Y.Z.); (R.-Y.P.); (L.-Z.M.); (J.D.); (L.Z.); (B.-W.Y.); (X.-L.Z.)
| | - Si-Mo Qiao
- Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing 100850, China; (S.-M.Q.); (H.-T.Y.)
| | - Yong Zou
- Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850, China; (W.-J.Z.); (Y.Z.); (R.-Y.P.); (L.-Z.M.); (J.D.); (L.Z.); (B.-W.Y.); (X.-L.Z.)
| | - Rui-Yun Peng
- Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850, China; (W.-J.Z.); (Y.Z.); (R.-Y.P.); (L.-Z.M.); (J.D.); (L.Z.); (B.-W.Y.); (X.-L.Z.)
| | - Hai-Tao Yan
- Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing 100850, China; (S.-M.Q.); (H.-T.Y.)
| | - Li-Zhen Ma
- Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850, China; (W.-J.Z.); (Y.Z.); (R.-Y.P.); (L.-Z.M.); (J.D.); (L.Z.); (B.-W.Y.); (X.-L.Z.)
| | - Ji Dong
- Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850, China; (W.-J.Z.); (Y.Z.); (R.-Y.P.); (L.-Z.M.); (J.D.); (L.Z.); (B.-W.Y.); (X.-L.Z.)
| | - Li Zhao
- Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850, China; (W.-J.Z.); (Y.Z.); (R.-Y.P.); (L.-Z.M.); (J.D.); (L.Z.); (B.-W.Y.); (X.-L.Z.)
| | - Bin-Wei Yao
- Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850, China; (W.-J.Z.); (Y.Z.); (R.-Y.P.); (L.-Z.M.); (J.D.); (L.Z.); (B.-W.Y.); (X.-L.Z.)
| | - Xue-Long Zhao
- Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850, China; (W.-J.Z.); (Y.Z.); (R.-Y.P.); (L.-Z.M.); (J.D.); (L.Z.); (B.-W.Y.); (X.-L.Z.)
| | - Xin-Xing Feng
- Endocrine and Cardiovascular Center, Cardiovascular Institute and Fuwai Hospital of Chinese Academy of Medical Sciences, Beijing 100850, China;
| | - Xiang-Jun Hu
- Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850, China; (W.-J.Z.); (Y.Z.); (R.-Y.P.); (L.-Z.M.); (J.D.); (L.Z.); (B.-W.Y.); (X.-L.Z.)
- Correspondence: (X.-J.H.); (L.-F.W.)
| | - Li-Feng Wang
- Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850, China; (W.-J.Z.); (Y.Z.); (R.-Y.P.); (L.-Z.M.); (J.D.); (L.Z.); (B.-W.Y.); (X.-L.Z.)
- Correspondence: (X.-J.H.); (L.-F.W.)
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5
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Fouke KE, Wegman ME, Weber SA, Brady EB, Román-Vendrell C, Morgan JR. Synuclein Regulates Synaptic Vesicle Clustering and Docking at a Vertebrate Synapse. Front Cell Dev Biol 2021; 9:774650. [PMID: 34901020 PMCID: PMC8660973 DOI: 10.3389/fcell.2021.774650] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Accepted: 11/10/2021] [Indexed: 11/17/2022] Open
Abstract
Neurotransmission relies critically on the exocytotic release of neurotransmitters from small synaptic vesicles (SVs) at the active zone. Therefore, it is essential for neurons to maintain an adequate pool of SVs clustered at synapses in order to sustain efficient neurotransmission. It is well established that the phosphoprotein synapsin 1 regulates SV clustering at synapses. Here, we demonstrate that synuclein, another SV-associated protein and synapsin binding partner, also modulates SV clustering at a vertebrate synapse. When acutely introduced to unstimulated lamprey reticulospinal synapses, a pan-synuclein antibody raised against the N-terminal domain of α-synuclein induced a significant loss of SVs at the synapse. Both docked SVs and the distal reserve pool of SVs were depleted, resulting in a loss of total membrane at synapses. In contrast, antibodies against two other abundant SV-associated proteins, synaptic vesicle glycoprotein 2 (SV2) and vesicle-associated membrane protein (VAMP/synaptobrevin), had no effect on the size or distribution of SV clusters. Synuclein perturbation caused a dose-dependent reduction in the number of SVs at synapses. Interestingly, the large SV clusters appeared to disperse into smaller SV clusters, as well as individual SVs. Thus, synuclein regulates clustering of SVs at resting synapses, as well as docking of SVs at the active zone. These findings reveal new roles for synuclein at the synapse and provide critical insights into diseases associated with α-synuclein dysfunction, such as Parkinson’s disease.
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Affiliation(s)
- Kaitlyn E Fouke
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States.,Department of Neurobiology, Duke University, Durham, NC, United States
| | - M Elizabeth Wegman
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
| | - Sarah A Weber
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States.,Biological Sciences Collegiate Division, The University of Chicago, Chicago, IL, United States
| | - Emily B Brady
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
| | - Cristina Román-Vendrell
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
| | - Jennifer R Morgan
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
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6
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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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7
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Function of Drosophila Synaptotagmins in membrane trafficking at synapses. Cell Mol Life Sci 2021; 78:4335-4364. [PMID: 33619613 PMCID: PMC8164606 DOI: 10.1007/s00018-021-03788-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/29/2021] [Accepted: 02/09/2021] [Indexed: 12/13/2022]
Abstract
The Synaptotagmin (SYT) family of proteins play key roles in regulating membrane trafficking at neuronal synapses. Using both Ca2+-dependent and Ca2+-independent interactions, several SYT isoforms participate in synchronous and asynchronous fusion of synaptic vesicles (SVs) while preventing spontaneous release that occurs in the absence of stimulation. Changes in the function or abundance of the SYT1 and SYT7 isoforms alter the number and route by which SVs fuse at nerve terminals. Several SYT family members also regulate trafficking of other subcellular organelles at synapses, including dense core vesicles (DCV), exosomes, and postsynaptic vesicles. Although SYTs are linked to trafficking of multiple classes of synaptic membrane compartments, how and when they interact with lipids, the SNARE machinery and other release effectors are still being elucidated. Given mutations in the SYT family cause disorders in both the central and peripheral nervous system in humans, ongoing efforts are defining how these proteins regulate vesicle trafficking within distinct neuronal compartments. Here, we review the Drosophila SYT family and examine their role in synaptic communication. Studies in this invertebrate model have revealed key similarities and several differences with the predicted activity of their mammalian counterparts. In addition, we highlight the remaining areas of uncertainty in the field and describe outstanding questions on how the SYT family regulates membrane trafficking at nerve terminals.
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8
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Silbern I, Pan KT, Fiosins M, Bonn S, Rizzoli SO, Fornasiero EF, Urlaub H, Jahn R. Protein Phosphorylation in Depolarized Synaptosomes: Dissecting Primary Effects of Calcium from Synaptic Vesicle Cycling. Mol Cell Proteomics 2021; 20:100061. [PMID: 33582301 PMCID: PMC7995663 DOI: 10.1016/j.mcpro.2021.100061] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 02/02/2021] [Indexed: 01/20/2023] Open
Abstract
Synaptic transmission is mediated by the regulated exocytosis of synaptic vesicles. When the presynaptic membrane is depolarized by an incoming action potential, voltage-gated calcium channels open, resulting in the influx of calcium ions that triggers the fusion of synaptic vesicles (SVs) with the plasma membrane. SVs are recycled by endocytosis. Phosphorylation of synaptic proteins plays a major role in these processes, and several studies have shown that the synaptic phosphoproteome changes rapidly in response to depolarization. However, it is unclear which of these changes are directly linked to SV cycling and which might regulate other presynaptic functions that are also controlled by calcium-dependent kinases and phosphatases. To address this question, we analyzed changes in the phosphoproteome using rat synaptosomes in which exocytosis was blocked with botulinum neurotoxins (BoNTs) while depolarization-induced calcium influx remained unchanged. BoNT-treatment significantly alters the response of the synaptic phoshoproteome to depolarization and results in reduced phosphorylation levels when compared with stimulation of synaptosomes by depolarization with KCl alone. We dissect the primary Ca2+-dependent phosphorylation from SV-cycling-dependent phosphorylation and confirm an effect of such SV-cycling-dependent phosphorylation events on syntaxin-1a-T21/T23, synaptobrevin-S75, and cannabinoid receptor-1-S314/T322 on exo- and endocytosis in cultured hippocampal neurons.
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Affiliation(s)
- Ivan Silbern
- Institute of Clinical Chemistry, University Medical Center Goettingen, Goettingen, Germany; Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Goettingen, Germany
| | - Kuan-Ting Pan
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Goettingen, Germany
| | - Maksims Fiosins
- German Center for Neurodegenerative Diseases, Tübingen, Germany; Institute for Medical Systems Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Stefan Bonn
- German Center for Neurodegenerative Diseases, Tübingen, Germany; Institute for Medical Systems Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Silvio O Rizzoli
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Goettingen, Göttingen, Germany
| | - Eugenio F Fornasiero
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany.
| | - Henning Urlaub
- Institute of Clinical Chemistry, University Medical Center Goettingen, Goettingen, Germany; Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Goettingen, Germany.
| | - Reinhard Jahn
- Laboratory of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
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9
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Park D, Wu Y, Lee SE, Kim G, Jeong S, Milovanovic D, De Camilli P, Chang S. Cooperative function of synaptophysin and synapsin in the generation of synaptic vesicle-like clusters in non-neuronal cells. Nat Commun 2021; 12:263. [PMID: 33431828 PMCID: PMC7801664 DOI: 10.1038/s41467-020-20462-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 12/02/2020] [Indexed: 02/01/2023] Open
Abstract
Clusters of tightly packed synaptic vesicles (SVs) are a defining feature of nerve terminals. While SVs are mobile within the clusters, the clusters have no boundaries consistent with a liquid phase. We previously found that purified synapsin, a peripheral SV protein, can assemble into liquid condensates and trap liposomes into them. How this finding relates to the physiological formation of SV clusters in living cells remains unclear. Here, we report that synapsin alone, when expressed in fibroblasts, has a diffuse cytosolic distribution. However, when expressed together with synaptophysin, an integral SV membrane protein previously shown to be localized on small synaptic-like microvesicles when expressed in non-neuronal cells, is sufficient to organize such vesicles in clusters highly reminiscent of SV clusters and with liquid-like properties. This minimal reconstitution system can be a powerful model to gain mechanistic insight into the assembly of structures which are of fundamental importance in synaptic transmission. Synaptic vesicle clusters were proposed to represent phase separated condensates. Here, the authors show that only two proteins, synapsin and synaptophysin, are sufficient to make vesicle clusters in fibroblasts which are similar to those found at synapses in morphology and liquid-like properties.
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Affiliation(s)
- Daehun Park
- Departments of Neuroscience and Cell Biology, Howard Hughes Medical Institute, Program in Cellular Neuroscience, Neurodegeneration and Repair, Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Yumei Wu
- Departments of Neuroscience and Cell Biology, Howard Hughes Medical Institute, Program in Cellular Neuroscience, Neurodegeneration and Repair, Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Sang-Eun Lee
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Goeun Kim
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Seonyoung Jeong
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Dragomir Milovanovic
- Departments of Neuroscience and Cell Biology, Howard Hughes Medical Institute, Program in Cellular Neuroscience, Neurodegeneration and Repair, Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, 06510, USA.,Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Charitéplatz 1, 10117, Berlin, Germany
| | - Pietro De Camilli
- Departments of Neuroscience and Cell Biology, Howard Hughes Medical Institute, Program in Cellular Neuroscience, Neurodegeneration and Repair, Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, 06510, USA.
| | - Sunghoe Chang
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, South Korea.
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10
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Savino E, Cervigni RI, Povolo M, Stefanetti A, Ferrante D, Valente P, Corradi A, Benfenati F, Guarnieri FC, Valtorta F. Proline-rich transmembrane protein 2 (PRRT2) regulates the actin cytoskeleton during synaptogenesis. Cell Death Dis 2020; 11:856. [PMID: 33056987 PMCID: PMC7560900 DOI: 10.1038/s41419-020-03073-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 09/25/2020] [Accepted: 09/28/2020] [Indexed: 12/13/2022]
Abstract
Mutations in proline-rich transmembrane protein 2 (PRRT2) have been recently identified as the leading cause of a clinically heterogeneous group of neurological disorders sharing a paroxysmal nature, including paroxysmal kinesigenic dyskinesia and benign familial infantile seizures. To date, studies aimed at understanding its physiological functions in neurons have mainly focused on its ability to regulate neurotransmitter release and neuronal excitability. Here, we show that PRRT2 expression in non-neuronal cell lines inhibits cell motility and focal adhesion turnover, increases cell aggregation propensity, and promotes the protrusion of filopodia, all processes impinging on the actin cytoskeleton. In primary hippocampal neurons, PRRT2 silencing affects the synaptic content of filamentous actin and perturbs actin dynamics. This is accompanied by defects in the density and maturation of dendritic spines. We identified cofilin, an actin-binding protein abundantly expressed at the synaptic level, as the ultimate effector of PRRT2. Indeed, PRRT2 silencing unbalances cofilin activity leading to the formation of cofilin-actin rods along neurites. The expression of a cofilin phospho-mimetic mutant (cof-S3E) is able to rescue PRRT2-dependent defects in synapse density, spine number and morphology, but not the alterations observed in neurotransmitter release. Our data support a novel function of PRRT2 in the regulation of the synaptic actin cytoskeleton and in the formation of synaptic contacts.
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Affiliation(s)
- Elisa Savino
- IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132, Milan, Italy.,Vita-Salute San Raffaele University, Via Olgettina 58, 20132, Milan, Italy
| | - Romina Inès Cervigni
- IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132, Milan, Italy.,Vita-Salute San Raffaele University, Via Olgettina 58, 20132, Milan, Italy
| | - Miriana Povolo
- IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132, Milan, Italy.,Vita-Salute San Raffaele University, Via Olgettina 58, 20132, Milan, Italy
| | | | - Daniele Ferrante
- Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132, Genova, Italy
| | - Pierluigi Valente
- Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132, Genova, Italy.,IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132, Genova, Italy
| | - Anna Corradi
- Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132, Genova, Italy.,IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132, Genova, Italy
| | - Fabio Benfenati
- IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132, Genova, Italy.,Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132, Genova, Italy
| | - Fabrizia Claudia Guarnieri
- IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132, Milan, Italy.,Vita-Salute San Raffaele University, Via Olgettina 58, 20132, Milan, Italy
| | - Flavia Valtorta
- IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132, Milan, Italy. .,Vita-Salute San Raffaele University, Via Olgettina 58, 20132, Milan, Italy.
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11
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Khalid A, Abbasi UA, Amber S, Sumera, Mirza FJ, Asif M, Javed A, Zahid S. Methylphenidate and Rosmarinus officinalis improves cognition and regulates inflammation and synaptic gene expression in AlCl 3-induced neurotoxicity mouse model. Mol Biol Rep 2020; 47:7861-7870. [PMID: 33011892 DOI: 10.1007/s11033-020-05864-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 09/04/2020] [Accepted: 09/25/2020] [Indexed: 12/27/2022]
Abstract
Methylphenidate (MPH), a psychotropic medication is commonly used for children with attention deficit hyperactivity disorder (ADHD). In this study we elucidated the neuroprotective and anti-inflammatory effects of MPH and Rosmarinus officinalis (rosemary) extract, an ancient aromatic herb with several applications in traditional medicine. Briefly, six groups of mice (n = 8 each group), were specified for the study and behavioral analysis was performed to analyze spatial memory followed by histological assessment and gene expression analysis of synaptic (Syn I, II and III) and inflammatory markers (IL-6, TNFα and GFAP) via qRT-PCR, in an AlCl3-induced mouse model for neurotoxicity. The behavioral analysis demonstrated significant cognitive decline, memory defects and altered gene expression in AlCl3-treated group. Rosemary extract significantly decreased the expression of inflammatory and synaptic markers to the similar levels as that of MPH. The present findings suggested the neuroprotective potential of Rosmarinus officinalis extract. However, further characterization of its anti-inflammatory and neuroprotective properties and MPH is required to strategize future treatments for several neurological and neurodegenerative disorders, including Alzheimer's disease.
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Affiliation(s)
- Anibah Khalid
- Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, Pakistan
| | - Umme Aimen Abbasi
- Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, Pakistan
| | - Sanila Amber
- Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, Pakistan
| | - Sumera
- Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, Pakistan
| | - Fatima Javed Mirza
- Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, Pakistan
| | - Muhammad Asif
- Department of Histopathology, Armed Forces Institute of Pathology, Rawalpindi, Pakistan
| | - Aneela Javed
- Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, Pakistan
| | - Saadia Zahid
- Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, Pakistan.
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12
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Reshetniak S, Ußling JE, Perego E, Rammner B, Schikorski T, Fornasiero EF, Truckenbrodt S, Köster S, Rizzoli SO. A comparative analysis of the mobility of 45 proteins in the synaptic bouton. EMBO J 2020; 39:e104596. [PMID: 32627850 PMCID: PMC7429486 DOI: 10.15252/embj.2020104596] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 05/20/2020] [Accepted: 05/29/2020] [Indexed: 02/01/2023] Open
Abstract
Many proteins involved in synaptic transmission are well known, and their features, as their abundance or spatial distribution, have been analyzed in systematic studies. This has not been the case, however, for their mobility. To solve this, we analyzed the motion of 45 GFP‐tagged synaptic proteins expressed in cultured hippocampal neurons, using fluorescence recovery after photobleaching, particle tracking, and modeling. We compared synaptic vesicle proteins, endo‐ and exocytosis cofactors, cytoskeleton components, and trafficking proteins. We found that movement was influenced by the protein association with synaptic vesicles, especially for membrane proteins. Surprisingly, protein mobility also correlated significantly with parameters as the protein lifetimes, or the nucleotide composition of their mRNAs. We then analyzed protein movement thoroughly, taking into account the spatial characteristics of the system. This resulted in a first visualization of overall protein motion in the synapse, which should enable future modeling studies of synaptic physiology.
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Affiliation(s)
- Sofiia Reshetniak
- Institute for Neuro- and Sensory Physiology and Biostructural Imaging of Neurodegeneration (BIN) Center, University Medical Center Göttingen, Göttingen, Germany.,International Max Planck Research School for Molecular Biology, Göttingen, Germany
| | - Jan-Eike Ußling
- Institute for Neuro- and Sensory Physiology and Biostructural Imaging of Neurodegeneration (BIN) Center, University Medical Center Göttingen, Göttingen, Germany
| | - Eleonora Perego
- Institute for X-Ray Physics, University of Göttingen, Göttingen, Germany
| | - Burkhard Rammner
- Institute for Neuro- and Sensory Physiology and Biostructural Imaging of Neurodegeneration (BIN) Center, University Medical Center Göttingen, Göttingen, Germany
| | - Thomas Schikorski
- Department of Neuroscience, Universidad Central del Caribe, Bayamon, PR, USA
| | - Eugenio F Fornasiero
- Institute for Neuro- and Sensory Physiology and Biostructural Imaging of Neurodegeneration (BIN) Center, University Medical Center Göttingen, Göttingen, Germany
| | - Sven Truckenbrodt
- Institute for Neuro- and Sensory Physiology and Biostructural Imaging of Neurodegeneration (BIN) Center, University Medical Center Göttingen, Göttingen, Germany.,International Max Planck Research School for Molecular Biology, Göttingen, Germany
| | - Sarah Köster
- Institute for X-Ray Physics, University of Göttingen, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | - Silvio O Rizzoli
- Institute for Neuro- and Sensory Physiology and Biostructural Imaging of Neurodegeneration (BIN) Center, University Medical Center Göttingen, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
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13
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Patzke C, Brockmann MM, Dai J, Gan KJ, Grauel MK, Fenske P, Liu Y, Acuna C, Rosenmund C, Südhof TC. Neuromodulator Signaling Bidirectionally Controls Vesicle Numbers in Human Synapses. Cell 2020; 179:498-513.e22. [PMID: 31585084 DOI: 10.1016/j.cell.2019.09.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 06/28/2019] [Accepted: 09/06/2019] [Indexed: 10/25/2022]
Abstract
Neuromodulators bind to pre- and postsynaptic G protein-coupled receptors (GPCRs), are able to quickly change intracellular cyclic AMP (cAMP) and Ca2+ levels, and are thought to play important roles in neuropsychiatric and neurodegenerative diseases. Here, we discovered in human neurons an unanticipated presynaptic mechanism that acutely changes synaptic ultrastructure and regulates synaptic communication. Activation of neuromodulator receptors bidirectionally controlled synaptic vesicle numbers within nerve terminals. This control correlated with changes in the levels of cAMP-dependent protein kinase A-mediated phosphorylation of synapsin-1. Using a conditional deletion approach, we reveal that the neuromodulator-induced control of synaptic vesicle numbers was largely dependent on synapsin-1. We propose a mechanism whereby non-phosphorylated synapsin-1 "latches" synaptic vesicles to presynaptic clusters at the active zone. cAMP-dependent phosphorylation of synapsin-1 then removes the vesicles. cAMP-independent dephosphorylation of synapsin-1 in turn recruits vesicles. Synapsin-1 thereby bidirectionally regulates synaptic vesicle numbers and modifies presynaptic neurotransmitter release as an effector of neuromodulator signaling in human neurons.
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Affiliation(s)
- Christopher Patzke
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305, USA.
| | - Marisa M Brockmann
- Institut für Neurophysiologie, Charité Universitätsmedizin, 10117 Berlin, Germany
| | - Jinye Dai
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305, USA
| | - Kathlyn J Gan
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305, USA
| | - M Katharina Grauel
- Institut für Neurophysiologie, Charité Universitätsmedizin, 10117 Berlin, Germany
| | - Pascal Fenske
- Institut für Neurophysiologie, Charité Universitätsmedizin, 10117 Berlin, Germany
| | - Yu Liu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305, USA
| | - Claudio Acuna
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305, USA
| | - Christian Rosenmund
- Institut für Neurophysiologie, Charité Universitätsmedizin, 10117 Berlin, Germany
| | - Thomas C Südhof
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305, USA
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14
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Keihani S, Kluever V, Mandad S, Bansal V, Rahman R, Fritsch E, Gomes LC, Gärtner A, Kügler S, Urlaub H, Wren JD, Bonn S, Rizzoli SO, Fornasiero EF. The long noncoding RNA neuroLNC regulates presynaptic activity by interacting with the neurodegeneration-associated protein TDP-43. SCIENCE ADVANCES 2019; 5:eaay2670. [PMID: 31897430 PMCID: PMC6920028 DOI: 10.1126/sciadv.aay2670] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 10/23/2019] [Indexed: 05/26/2023]
Abstract
The cellular and the molecular mechanisms by which long noncoding RNAs (lncRNAs) may regulate presynaptic function and neuronal activity are largely unexplored. Here, we established an integrated screening strategy to discover lncRNAs implicated in neurotransmitter and synaptic vesicle release. With this approach, we identified neuroLNC, a neuron-specific nuclear lncRNA conserved from rodents to humans. NeuroLNC is tuned by synaptic activity and influences several other essential aspects of neuronal development including calcium influx, neuritogenesis, and neuronal migration in vivo. We defined the molecular interactors of neuroLNC in detail using chromatin isolation by RNA purification, RNA interactome analysis, and protein mass spectrometry. We found that the effects of neuroLNC on synaptic vesicle release require interaction with the RNA-binding protein TDP-43 (TAR DNA binding protein-43) and the selective stabilization of mRNAs encoding for presynaptic proteins. These results provide the first proof of an lncRNA that orchestrates neuronal excitability by influencing presynaptic function.
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Affiliation(s)
- S. Keihani
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Excellence Cluster Multiscale Bioimaging, 37073 Göttingen, Germany
| | - V. Kluever
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Excellence Cluster Multiscale Bioimaging, 37073 Göttingen, Germany
| | - S. Mandad
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Excellence Cluster Multiscale Bioimaging, 37073 Göttingen, Germany
- Department of Clinical Chemistry, University Medical Center Göttingen, 37077 Göttingen, Germany
| | - V. Bansal
- Institute of Medical Systems Biology, Center for Molecular Neurobiology (ZMNH), UKE, 20246 Hamburg, Germany
- German Center for Neurodegenerative Diseases (DZNE), 72076 Tübingen, Germany
| | - R. Rahman
- Institute of Medical Systems Biology, Center for Molecular Neurobiology (ZMNH), UKE, 20246 Hamburg, Germany
| | - E. Fritsch
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Excellence Cluster Multiscale Bioimaging, 37073 Göttingen, Germany
| | - L. Caldi Gomes
- Department of Neurology, University Medical Center Göttingen, 37073 Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration (BIN), 37075 Göttingen, Germany
| | - A. Gärtner
- VIB Center for the Biology of Disease and Center for Human Genetics, KU Leuven, Leuven, Belgium
| | - S. Kügler
- Department of Neurology, University Medical Center Göttingen, 37073 Göttingen, Germany
| | - H. Urlaub
- Department of Clinical Chemistry, University Medical Center Göttingen, 37077 Göttingen, Germany
- Bioanalytical Mass Spectrometry Group, Max Planck Institute of Biophysical Chemistry, 37077 Göttingen, Germany
| | - J. D. Wren
- Department of Genes and Human Disease, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - S. Bonn
- Institute of Medical Systems Biology, Center for Molecular Neurobiology (ZMNH), UKE, 20246 Hamburg, Germany
- German Center for Neurodegenerative Diseases (DZNE), 72076 Tübingen, Germany
| | - S. O. Rizzoli
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Excellence Cluster Multiscale Bioimaging, 37073 Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration (BIN), 37075 Göttingen, Germany
| | - E. F. Fornasiero
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Excellence Cluster Multiscale Bioimaging, 37073 Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration (BIN), 37075 Göttingen, Germany
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15
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Dobson KL, Howe CL, Nishimura Y, Marra V. Dedicated Setup for the Photoconversion of Fluorescent Dyes for Functional Electron Microscopy. Front Cell Neurosci 2019; 13:312. [PMID: 31417358 PMCID: PMC6681119 DOI: 10.3389/fncel.2019.00312] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 06/25/2019] [Indexed: 11/22/2022] Open
Abstract
Here, we describe a cost-effective setup for targeted photoconversion of fluorescent signals into electron dense ones. This approach has offered invaluable insights in the morphology and function of fine neuronal structures. The technique relies on the localized oxidation of diaminobenzidine (DAB) mediated by excited fluorophores. This paper includes a detailed description of how to build a simple photoconversion setup that can increase reliability and throughput of this well-established technique. The system described here, is particularly well-suited for thick neuronal tissue, where light penetration and oxygen diffusion may be limiting DAB oxidation. To demonstrate the system, we use Correlative Light and Electron Microscopy (CLEM) to visualize functionally-labeled individual synaptic vesicles released onto an identified layer 5 neuron in an acute cortical slice. The setup significantly simplifies the photoconversion workflow, increasing the depth of photoillumination, improving the targeting of the region of interest and reducing the time required to process each individual sample. We have tested this setup extensively for the photoconversion of FM 1-43FX and Lucifer Yellow both excited at 473 nm. In principle, the system can be adapted to any dye or nanoparticle able to oxidize DAB when excited by a specific wavelength of light.
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Affiliation(s)
- Katharine L. Dobson
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Carmel L. Howe
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Yuri Nishimura
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Vincenzo Marra
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
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16
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Cornel iridoid glycoside induces autophagy to protect against tau oligomer neurotoxicity induced by the activation of glycogen synthase kinase-3β. J Nat Med 2019; 73:717-726. [DOI: 10.1007/s11418-019-01318-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 05/07/2019] [Indexed: 12/20/2022]
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17
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An integrated transcriptomics and proteomics analysis reveals functional endocytic dysregulation caused by mutations in LRRK2. Neurobiol Dis 2019; 127:512-526. [PMID: 30954703 PMCID: PMC6597903 DOI: 10.1016/j.nbd.2019.04.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 03/20/2019] [Accepted: 04/03/2019] [Indexed: 12/02/2022] Open
Abstract
Background Mutations in LRRK2 are the most common cause of autosomal dominant Parkinson's disease, and the relevance of LRRK2 to the sporadic form of the disease is becoming ever more apparent. It is therefore essential that studies are conducted to improve our understanding of the cellular role of this protein. Here we use multiple models and techniques to identify the pathways through which LRRK2 mutations may lead to the development of Parkinson's disease. Methods A novel integrated transcriptomics and proteomics approach was used to identify pathways that were significantly altered in iPSC-derived dopaminergic neurons carrying the LRRK2-G2019S mutation. Western blotting, immunostaining and functional assays including FM1-43 analysis of synaptic vesicle endocytosis were performed to confirm these findings in iPSC-derived dopaminergic neuronal cultures carrying either the LRRK2-G2019S or the LRRK2-R1441C mutation, and LRRK2 BAC transgenic rats, and post-mortem human brain tissue from LRRK2-G2019S patients. Results Our integrated -omics analysis revealed highly significant dysregulation of the endocytic pathway in iPSC-derived dopaminergic neurons carrying the LRRK2-G2019S mutation. Western blot analysis confirmed that key endocytic proteins including endophilin I-III, dynamin-1, and various RAB proteins were downregulated in these cultures and in cultures carrying the LRRK2-R1441C mutation, compared with controls. We also found changes in expression of 25 RAB proteins. Changes in endocytic protein expression led to a functional impairment in clathrin-mediated synaptic vesicle endocytosis. Further to this, we found that the endocytic pathway was also perturbed in striatal tissue of aged LRRK2 BAC transgenic rats overexpressing either the LRRK2 wildtype, LRRK2-R1441C or LRRK2-G2019S transgenes. Finally, we found that clathrin heavy chain and endophilin I-III levels are increased in human post-mortem tissue from LRRK2-G2019S patients compared with controls. Conclusions Our study demonstrates extensive alterations across the endocytic pathway associated with LRRK2 mutations in iPSC-derived dopaminergic neurons and BAC transgenic rats, as well as in post-mortem brain tissue from PD patients carrying a LRRK2 mutation. In particular, we find evidence of disrupted clathrin-mediated endocytosis and suggest that LRRK2-mediated PD pathogenesis may arise through dysregulation of this process. iPSC-derived dopaminergic neurons from LRRK2 patients show extensive endocytic changes. Integrated proteomic and transcriptomic approach reveals dysregulation of 25 RABs. Functional impairment of clathrin mediated endocytosis in LRRK2 iPSC-dopaminergic neurons. Aged LRRK2 rats also show similar perturbations of key endocytic proteins. LRRK2 human post-mortem tissue shows upregulation of clathrin and endophilin.
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18
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Narita K, Suzuki N, Himi N, Murayama T, Nakagawa T, Okabe N, Nakamura-Maruyama E, Hayashi N, Sakamoto I, Miyamoto O, Kuba K. Effects of intravesicular loading of a Ca 2+ chelator and depolymerization of actin fibers on neurotransmitter release in frog motor nerve terminals. Eur J Neurosci 2019; 50:1700-1711. [PMID: 30687962 DOI: 10.1111/ejn.14353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 01/08/2019] [Accepted: 01/08/2019] [Indexed: 11/27/2022]
Abstract
Ca2+ -induced Ca2+ release (CICR) via type-3 ryanodine receptor enhances neurotransmitter release in frog motor nerve terminals. To test a possible role of synaptic vesicle in CICR, we examined the effects of loading of EGTA, a Ca2+ chelator, into synaptic vesicles and depolymerization of actin fibers. Intravesicular EGTA loading via endocytosis inhibited the ryanodine sensitive enhancement of transmitter release induced by tetanic stimulation and the associated rises in intracellular-free Ca2+ ([Ca2+ ]i : Ca2+ transients). Latrunculin A, a depolymerizer of actin fibers, enhanced both spontaneous and stimulation-induced transmitter release, but inhibited the enhancement of transmitter release elicited by successive tetanic stimulation. The results suggest a possibility that the activation of CICR from mobilized synaptic vesicles caused the enhancement of neurotransmitter release.
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Affiliation(s)
- Kazuhiko Narita
- Department of Physiology, Kawasaki Medical School, Kurashiki, Japan
| | - Naoya Suzuki
- Department of Physics, School of Sciences, Nagoya University, Nagoya, Japan
| | - Naoyuki Himi
- Department of Physiology, Kawasaki Medical School, Kurashiki, Japan
| | | | | | - Naohiko Okabe
- Department of Physiology, Kawasaki Medical School, Kurashiki, Japan
| | | | - Norito Hayashi
- Department of Physiology, Kawasaki Medical School, Kurashiki, Japan
| | - Issei Sakamoto
- Department of Physiology, Kawasaki Medical School, Kurashiki, Japan
| | - Osamu Miyamoto
- Department of Physiology, Kawasaki Medical School, Kurashiki, Japan
| | - Kenji Kuba
- Department of Physiology, School of Medicine, Nagoya University, Nagoya, Japan
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19
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Chen X, Wang X, Yang Y, Li Z, Zhang Y, Gao W, Xiao J, Li B. Schwann cells protect against CaMKII- and PKA-dependent Acrylamide-induced Synapsin I phosphorylation. Brain Res 2018; 1701:18-27. [PMID: 30028969 DOI: 10.1016/j.brainres.2018.07.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 07/11/2018] [Accepted: 07/13/2018] [Indexed: 11/26/2022]
Abstract
OBJECTIVES To explore the effects of Acrylamide (ACR), as well as the influence of Schwann cells (SCs), on the signal transduction pathway and phosphorylation of Synapsin I in a Human neuroblastoma cell line (NB-1). METHODS NB-1s, NB-1s co-cultured with SCs, and a negative control group (NB-1 cells without ACR) were exposed to gradient concentrations of ACR for 48 h. Cell proliferation and viability were determined by MTT. Protein and mRNA expression levels of typical kinases (i.e., cAMP-dependent protein kinase [PKA], calcium/calmodulin-dependent protein kinase II [CaMKII], and mitogen-activated protein kinase-extracellular signal-regulated kinases [MAPK-Erk]), their phosphorylation status, as well as Synapsin I and its phosphorylation status, were tested by western blotting and polymerase chain reaction, respectively. Further, the effect of SCs on ACR-induced NB-1 cell toxicity was evaluated. RESULTS (1) The MTT assay showed a sustained, dose- and time-dependent inhibition of NB-1s exposed to ACR. (2) ACR exposure increased the phosphorylation of CaMKII and PKA, which subsequently increased the phosphorylation of Synapsin I (at Serine603 [a substrate site of CaMKII] and Serine9 [a substrate site of PKA]). Pretreatment with CaMKII and PKA inhibitors blocked the ACR-mediated increase in phosphorylation. The above-described results were all significantly different when compared to the control group (p < 0.05). (3) When co-cultured with SCs, ACR-induced NB-1 inhibition was obviously decreased, and the trend of change of phosphorylated CaMKII, PKA, and Synapsin I were changed (first slightly increased and then decreased), which was inconsistent with what we observed in NB-1s cultured alone. CONCLUSIONS The toxic effects of ACR on neurons may be mediated by CaMKII and PKA-dependent signaling pathways in which Synapsin I may act as a downstream effector. Furthermore, glial cells (SCs) may be able to prevent a certain degree of ACR-induced neuronal damage.
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Affiliation(s)
- Xiao Chen
- Department of Toxicology, Key Lab of Chemical Safety and Health, National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China
| | - Xiuhui Wang
- Department of Toxicology, Key Lab of Chemical Safety and Health, National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China
| | - Yiguang Yang
- Department of Toxicology, Key Lab of Chemical Safety and Health, National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China
| | - Zhongsheng Li
- Department of Toxicology, Key Lab of Chemical Safety and Health, National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China
| | - Yi Zhang
- Department of Toxicology, Key Lab of Chemical Safety and Health, National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China
| | - Weimin Gao
- Department of Occupational and Environmental Health Sciences, School of Public Health, West Virginia University, West Virginia, USA
| | - Jingwei Xiao
- Department of Toxicology, Key Lab of Chemical Safety and Health, National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
| | - Bin Li
- Department of Toxicology, Key Lab of Chemical Safety and Health, National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
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20
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How Do Synaptic Vesicles "Know" Which Pool They Belong to? J Neurosci 2018; 37:2276-2278. [PMID: 28250057 DOI: 10.1523/jneurosci.3889-16.2017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 01/20/2017] [Accepted: 01/27/2017] [Indexed: 12/19/2022] Open
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21
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Guarnieri FC, Pozzi D, Raimondi A, Fesce R, Valente MM, Delvecchio VS, Van Esch H, Matteoli M, Benfenati F, D'Adamo P, Valtorta F. A novel SYN1 missense mutation in non-syndromic X-linked intellectual disability affects synaptic vesicle life cycle, clustering and mobility. Hum Mol Genet 2018; 26:4699-4714. [PMID: 28973667 DOI: 10.1093/hmg/ddx352] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 08/29/2017] [Indexed: 01/04/2023] Open
Abstract
Intellectual Disability is a common and heterogeneous disorder characterized by limitations in intellectual functioning and adaptive behaviour, whose molecular mechanisms remain largely unknown. Among the numerous genes found to be involved in the pathogenesis of intellectual disability, 10% are located on the X-chromosome. We identified a missense mutation (c.236 C > G; p.S79W) in the SYN1 gene coding for synapsin I in the MRX50 family, affected by non-syndromic X-linked intellectual disability. Synapsin I is a neuronal phosphoprotein involved in the regulation of neurotransmitter release and neuronal development. Several mutations in SYN1 have been identified in patients affected by epilepsy and/or autism. The S79W mutation segregates with the disease in the MRX50 family and all affected members display intellectual disability as sole clinical manifestation. At the protein level, the S79W Synapsin I mutation is located in the region of the B-domain involved in recognition of highly curved membranes. Expression of human S79W Synapsin I in Syn1 knockout hippocampal neurons causes aberrant accumulation of small clear vesicles in the soma, increased clustering of synaptic vesicles at presynaptic terminals and increased frequency of excitatory spontaneous release events. In addition, the presence of S79W Synapsin I strongly reduces the mobility of synaptic vesicles, with possible implications for the regulation of neurotransmitter release and synaptic plasticity. These results implicate SYN1 in the pathogenesis of non-syndromic intellectual disability, showing that alterations of synaptic vesicle trafficking are one possible cause of this disease, and suggest that distinct mutations in SYN1 may lead to distinct brain pathologies.
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Affiliation(s)
- Fabrizia C Guarnieri
- Division of Neuroscience, San Raffaele Scientific Institute, 20132 Milan, Italy.,San Raffaele Vita-Salute University, 20132 Milan, Italy
| | - Davide Pozzi
- Laboratory of Pharmacology and Brain Pathology, Humanitas Clinical and Research Center, 20089 Rozzano, Milan, Italy
| | - Andrea Raimondi
- Experimental Imaging Center, San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Riccardo Fesce
- Centre of Neuroscience and DISTA, University of Insubria, 21100 Varese, Italy
| | - Maria M Valente
- Division of Neuroscience, San Raffaele Scientific Institute, 20132 Milan, Italy
| | | | - Hilde Van Esch
- Center for Human Genetics, University Hospitals Leuven, B3000 Leuven, Belgium
| | - Michela Matteoli
- Laboratory of Pharmacology and Brain Pathology, Humanitas Clinical and Research Center, 20089 Rozzano, Milan, Italy.,CNR Institute of Neuroscience, Milan, Italy
| | - Fabio Benfenati
- Department of Experimental Medicine, University of Genova, 16132 Genova, Italy.,Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genova, Italy
| | - Patrizia D'Adamo
- Division of Neuroscience, San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Flavia Valtorta
- Division of Neuroscience, San Raffaele Scientific Institute, 20132 Milan, Italy.,San Raffaele Vita-Salute University, 20132 Milan, Italy
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22
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Hu Y, Pan S, Zhang HT. Interaction of Cdk5 and cAMP/PKA Signaling in the Mediation of Neuropsychiatric and Neurodegenerative Diseases. ADVANCES IN NEUROBIOLOGY 2018; 17:45-61. [PMID: 28956329 DOI: 10.1007/978-3-319-58811-7_3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Both cyclin-dependent kinase 5 (Cdk5) and cyclic AMP (cAMP)/protein kinase A (PKA) regulate fundamental central nervous system (CNS) functions including neuronal survival, neurite and axonal outgrowth, neuron development and cognition. Cdk5, a serine/threonine kinase, is activated by p35 or p39 and phosphorylates multiple signaling components of various pathways, including cAMP/PKA signaling. Here, we review the recent literature on the interaction between Cdk5 and cAMP/PKA signaling and their role in the mediation of CNS functions and neuropsychiatric and neurodegenerative diseases.
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Affiliation(s)
- Yafang Hu
- Department of Neurology, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Avenue, Guangzhou, Guangdong, 510515, China.
| | - Suyue Pan
- Department of Neurology, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Avenue, Guangzhou, Guangdong, 510515, China
| | - Han-Ting Zhang
- Department of Behavioral Medicine and Psychiatry, West Virginia University Health Sciences Center, 1 Medical Center Drive, Morgantown, WV, 26506, USA.,Department of Physiology and Pharmacology, West Virginia University Health Sciences Center, 1 Medical Center Drive, Morgantown, WV, 26506, USA.,Institute of Pharmacology, Taishan Medical University, Taian, 271016, China
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23
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Gilbert J, Man HY. Fundamental Elements in Autism: From Neurogenesis and Neurite Growth to Synaptic Plasticity. Front Cell Neurosci 2017; 11:359. [PMID: 29209173 PMCID: PMC5701944 DOI: 10.3389/fncel.2017.00359] [Citation(s) in RCA: 161] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 10/31/2017] [Indexed: 01/12/2023] Open
Abstract
Autism spectrum disorder (ASD) is a set of neurodevelopmental disorders with a high prevalence and impact on society. ASDs are characterized by deficits in both social behavior and cognitive function. There is a strong genetic basis underlying ASDs that is highly heterogeneous; however, multiple studies have highlighted the involvement of key processes, including neurogenesis, neurite growth, synaptogenesis and synaptic plasticity in the pathophysiology of neurodevelopmental disorders. In this review article, we focus on the major genes and signaling pathways implicated in ASD and discuss the cellular, molecular and functional studies that have shed light on common dysregulated pathways using in vitro, in vivo and human evidence. HighlightsAutism spectrum disorder (ASD) has a prevalence of 1 in 68 children in the United States. ASDs are highly heterogeneous in their genetic basis. ASDs share common features at the cellular and molecular levels in the brain. Most ASD genes are implicated in neurogenesis, structural maturation, synaptogenesis and function.
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Affiliation(s)
- James Gilbert
- Department of Biology, Boston University, Boston, MA, United States
| | - Heng-Ye Man
- Department of Biology, Boston University, Boston, MA, United States.,Department of Pharmacology & Experimental Therapeutics, Boston University School of Medicine, Boston, MA, United States
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24
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Intersectin associates with synapsin and regulates its nanoscale localization and function. Proc Natl Acad Sci U S A 2017; 114:12057-12062. [PMID: 29078407 PMCID: PMC5692602 DOI: 10.1073/pnas.1715341114] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mutations in genes regulating neurotransmission in the brain are implicated in neurological disorders and neurodegeneration. Synapsin is a crucial regulator of neurotransmission and allows synapses to maintain a large reserve pool of synaptic vesicles. Human mutations in synapsin genes are linked to epilepsy and autism. How synapsin function is regulated to allow replenishment of synaptic vesicles and sustain neurotransmission is largely unknown. Here we identify a function for the endocytic scaffold protein intersectin, a protein overexpressed in patients with Down syndrome, as a regulator of synapsin nanoscale distribution and function that is controlled by a phosphorylation-dependent autoinhibitory switch. Our results unravel a hitherto unknown molecular connection between the machineries for synaptic vesicle reserve pool organization and endocytosis. Neurotransmission is mediated by the exocytic release of neurotransmitters from readily releasable synaptic vesicles (SVs) at the active zone. To sustain neurotransmission during periods of elevated activity, release-ready vesicles need to be replenished from the reserve pool of SVs. The SV-associated synapsins are crucial for maintaining this reserve pool and regulate the mobilization of reserve pool SVs. How replenishment of release-ready SVs from the reserve pool is regulated and which other factors cooperate with synapsins in this process is unknown. Here we identify the endocytic multidomain scaffold protein intersectin as an important regulator of SV replenishment at hippocampal synapses. We found that intersectin directly associates with synapsin I through its Src-homology 3 A domain, and this association is regulated by an intramolecular switch within intersectin 1. Deletion of intersectin 1/2 in mice alters the presynaptic nanoscale distribution of synapsin I and causes defects in sustained neurotransmission due to defective SV replenishment. These phenotypes were rescued by wild-type intersectin 1 but not by a locked mutant of intersectin 1. Our data reveal intersectin as an autoinhibited scaffold that serves as a molecular linker between the synapsin-dependent reserve pool and the presynaptic endocytosis machinery.
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25
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Vilmont V, Cadot B, Ouanounou G, Gomes ER. A system for studying mechanisms of neuromuscular junction development and maintenance. Development 2016; 143:2464-77. [PMID: 27226316 PMCID: PMC4958317 DOI: 10.1242/dev.130278] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 05/12/2016] [Indexed: 12/12/2022]
Abstract
The neuromuscular junction (NMJ), a cellular synapse between a motor neuron and a skeletal muscle fiber, enables the translation of chemical cues into physical activity. The development of this special structure has been subject to numerous investigations, but its complexity renders in vivo studies particularly difficult to perform. In vitro modeling of the neuromuscular junction represents a powerful tool to delineate fully the fine tuning of events that lead to subcellular specialization at the pre-synaptic and post-synaptic sites. Here, we describe a novel heterologous co-culture in vitro method using rat spinal cord explants with dorsal root ganglia and murine primary myoblasts to study neuromuscular junctions. This system allows the formation and long-term survival of highly differentiated myofibers, motor neurons, supporting glial cells and functional neuromuscular junctions with post-synaptic specialization. Therefore, fundamental aspects of NMJ formation and maintenance can be studied using the described system, which can be adapted to model multiple NMJ-associated disorders.
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Affiliation(s)
- Valérie Vilmont
- Myology Research Center, UM76-INSERM U974-CNRS FRE 3617 Sorbonne Universités, UPMC Université Paris 06, Paris, France
| | - Bruno Cadot
- Myology Research Center, UM76-INSERM U974-CNRS FRE 3617 Sorbonne Universités, UPMC Université Paris 06, Paris, France
| | - Gilles Ouanounou
- FRE CNRS 3693 (U.N.I.C), Unité de Neuroscience, Information et Complexité CNRS, Bât. 33, 1 Ave de la Terasse, Gif sur Yvette 91198, France
| | - Edgar R Gomes
- Myology Research Center, UM76-INSERM U974-CNRS FRE 3617 Sorbonne Universités, UPMC Université Paris 06, Paris, France Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
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26
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Phosphorylation by PKA and Cdk5 Mediates the Early Effects of Synapsin III in Neuronal Morphological Maturation. J Neurosci 2015; 35:13148-59. [PMID: 26400944 DOI: 10.1523/jneurosci.1379-15.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Synapsin III (SynIII) is a neuron-specific phosphoprotein that plays a unique role in neuronal development. SynIII is phosphorylated by cAMP-dependent protein kinase (PKA) at a highly conserved phosphorylation site and by cyclin-dependent kinase-5 (Cdk5) at a newly described site. Although SynIII is known to be involved in axon elongation in vitro, the role of its phosphorylation by PKA and Cdk5 in the modulation of this process is unknown. We expressed either wild-type (WT) or phosphorylation-site mutants of SynIII in primary SynIII knock-out (KO) mouse neurons at early stages of in vitro development. Whereas the neurite elongation phenotype of SynIII KO neurons was fully rescued by the expression of WT SynIII, the expression of nonphosphorylatable and pseudo-phosphorylated PKA mutants was ineffective. Also, the nonphosphorylatable Cdk5 mutant was unable to rescue the neurite elongation phenotype of SynIII KO neurons. By contrast, the pseudo-phosphorylated mutant rescued the delay in neuronal maturation and axonal elongation, revealing a Cdk5-dependent regulation of SynIII function. Interestingly, SynIII KO neurons also exhibited decreased survival that was fully rescued by the expression of WT SynIII, but not by its phosphorylation mutants, and was associated with increased activated caspase3 and altered tropomyosin receptor kinase B isoform expression. These results indicate that PKA and Cdk5 phosphorylation is required for the physiological action of SynIII on axon specification and neurite outgrowth and that the expression of a functional SynIII is crucial for cell survival. Significance statement: Synapsin III is an atypical member of the synapsin family of synaptic vesicle-associated phosphoproteins that is precociously expressed in neurons and is downregulated afterward. Although experimental evidence suggests a specific role for Synapsin III in neuronal development, the molecular mechanisms are still largely unknown. We found that Synapsin III plays a central role in early stages of neuronal development involving neuronal survival, polarization, and neuritic growth and that these effects are dependent on phosphorylation by cAMP-dependent protein kinase and cyclin-dependent protein kinase-5. These results explain the recently described neurodevelopmental defects in the migration and orientation of Synapsin III-depleted cortical neurons and support the potential association of Synapsin III with neurodevelopmental disorders such as schizophrenia.
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27
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Winther ÅME, Vorontsova O, Rees KA, Näreoja T, Sopova E, Jiao W, Shupliakov O. An Endocytic Scaffolding Protein together with Synapsin Regulates Synaptic Vesicle Clustering in the Drosophila Neuromuscular Junction. J Neurosci 2015; 35:14756-70. [PMID: 26538647 PMCID: PMC6605226 DOI: 10.1523/jneurosci.1675-15.2015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 09/16/2015] [Accepted: 09/25/2015] [Indexed: 11/21/2022] Open
Abstract
Many endocytic proteins accumulate in the reserve pool of synaptic vesicles (SVs) in synapses and relocalize to the endocytic periactive zone during neurotransmitter release. Currently little is known about their functions outside the periactive zone. Here we show that in the Drosophila neuromuscular junction (NMJ), the endocytic scaffolding protein Dap160 colocalizes during the SV cycle and forms a functional complex with the SV-associated phosphoprotein synapsin, previously implicated in SV clustering. This direct interaction is strongly enhanced under phosphorylation-promoting conditions and is essential for proper localization of synapsin at NMJs. In a dap160 rescue mutant lacking the interaction between Dap160 and synapsin, perturbed reclustering of SVs during synaptic activity is observed. Our data indicate that in addition to the function in endocytosis, Dap160 is a component of a network of protein-protein interactions that serves for clustering of SVs in conjunction with synapsin. During the SV cycle, Dap160 interacts with synapsin dispersed from SVs and helps direct synapsin back to vesicles. The proteins function in synergy to achieve efficient clustering of SVs in the reserve pool. SIGNIFICANCE STATEMENT We provide the first evidence for the function of the SH3 domain interaction in synaptic vesicle (SV) organization at the synaptic active zone. Using Drosophila neuromuscular junction as a model synapse, we describe the molecular mechanism that enables the protein implicated in SV clustering, synapsin, to return to the pool of vesicles during neurotransmitter release. We also identify the endocytic scaffolding complex that includes Dap160 as a regulator of the events linking exocytosis and endocytosis in synapses.
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Affiliation(s)
- Åsa M E Winther
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Olga Vorontsova
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Kathryn A Rees
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Tuomas Näreoja
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Elena Sopova
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Wei Jiao
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Oleg Shupliakov
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
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28
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Lin Y, Dong J, Yan T, He X, Zheng X, Liang H, Sui M. Involuntary, forced and voluntary exercises are equally capable of inducing hippocampal plasticity and the recovery of cognitive function after stroke. Neurol Res 2015; 37:893-901. [DOI: 10.1179/1743132815y.0000000074] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Lunardi N, Oklopcic A, Prillaman M, Erisir A, Jevtovic-Todorovic V. Early Exposure to General Anesthesia Disrupts Spatial Organization of Presynaptic Vesicles in Nerve Terminals of the Developing Rat Subiculum. Mol Neurobiol 2015; 52:942-51. [PMID: 26048670 DOI: 10.1007/s12035-015-9246-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Indexed: 01/08/2023]
Abstract
Exposure to general anesthesia (GA) during critical stages of brain development induces widespread neuronal apoptosis and causes long-lasting behavioral deficits in numerous animal species. Although several studies have focused on the morphological fate of neurons dying acutely by GA-induced developmental neuroapoptosis, the effects of an early exposure to GA on the surviving synapses remain unclear. The aim of this study is to study whether exposure to GA disrupts the fine regulation of the dynamic spatial organization and trafficking of synaptic vesicles in presynaptic terminals. We exposed postnatal day 7 (PND7) rat pups to a clinically relevant anesthetic combination of midazolam, nitrous oxide, and isoflurane and performed a detailed ultrastructural analysis of the synaptic vesicle architecture at presynaptic terminals in the subiculum of rats at PND 12. In addition to a significant decrease in the density of presynaptic vesicles, we observed a reduction of docked vesicles, as well as a reduction of vesicles located within 100 nm from the active zone, in animals 5 days after an initial exposure to GA. We also found that the synaptic vesicles of animals exposed to GA are located more distally with respect to the plasma membrane than those of sham control animals and that the distance between presynaptic vesicles is increased in GA-exposed animals compared to sham controls. We report that exposure of immature rats to GA during critical stages of brain development causes significant disruption of the strategic topography of presynaptic vesicles within the nerve terminals of the subiculum.
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Affiliation(s)
- N Lunardi
- Department of Anesthesiology, University of Virginia Health System, PO Box 800710, Charlottesville, VA, 22908, USA,
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30
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Abstract
Synaptic vesicles release their vesicular contents to the extracellular space by Ca(2+)-triggered exocytosis. The Ca(2+)-triggered exocytotic process is regulated by synaptotagmin (Syt), a vesicular Ca(2+)-binding C2 domain protein. Synaptotagmin 1 (Syt1), the most studied major isoform among 16 Syt isoforms, mediates Ca(2+)-triggered synaptic vesicle exocytosis by interacting with the target membranes and SNARE/complexin complex. In synapses of the central nervous system, synaptobrevin 2, a major vesicular SNARE protein, forms a ternary SNARE complex with the plasma membrane SNARE proteins, syntaxin 1 and SNAP25. The affinities of Ca(2+)-dependent interactions between Syt1 and its targets (i.e., SNARE complexes and membranes) are well correlated with the efficacies of the corresponding exocytotic processes. Therefore, different SNARE protein isoforms and membrane lipids, which interact with Syt1 with various affinities, are capable of regulating the efficacy of Syt1-mediated exocytosis. Otoferlin, another type of vesicular C2 domain protein that binds to the membrane in a Ca(2+)-dependent manner, is also involved in the Ca(2+)-triggered synaptic vesicle exocytosis in auditory hair cells. However, the functions of otoferlin in the exocytotic process are not well understood. In addition, at least five different types of synaptic vesicle proteins such as synaptic vesicle protein 2, cysteine string protein α, rab3, synapsin, and a group of proteins containing four transmembrane regions, which includes synaptophysin, synaptogyrin, and secretory carrier membrane protein, are involved in modulating the exocytotic process by regulating the formation and trafficking of synaptic vesicles.
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Affiliation(s)
- Ok-Ho Shin
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas
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31
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Chen J, Yu S, Fu Y, Li X. Synaptic proteins and receptors defects in autism spectrum disorders. Front Cell Neurosci 2014; 8:276. [PMID: 25309321 PMCID: PMC4161164 DOI: 10.3389/fncel.2014.00276] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 08/21/2014] [Indexed: 12/27/2022] Open
Abstract
Recent studies have found that hundreds of genetic variants, including common and rare variants, rare and de novo mutations, and common polymorphisms contribute to the occurrence of autism spectrum disorders (ASDs). The mutations in a number of genes such as neurexin, neuroligin, postsynaptic density protein 95, SH3, and multiple ankyrin repeat domains 3 (SHANK3), synapsin, gephyrin, cadherin, and protocadherin, thousand-and-one-amino acid 2 kinase, and contactin, have been shown to play important roles in the development and function of synapses. In addition, synaptic receptors, such as gamma-aminobutyric acid receptors and glutamate receptors, have also been associated with ASDs. This review will primarily focus on the defects of synaptic proteins and receptors associated with ASDs and their roles in the pathogenesis of ASDs via synaptic pathways.
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Affiliation(s)
- Jianling Chen
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine Shanghai, China
| | - Shunying Yu
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine Shanghai, China
| | - Yingmei Fu
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine Shanghai, China
| | - Xiaohong Li
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities Staten Island, NY USA
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32
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Chanaday NL, Vilcaes AA, de Paul AL, Torres AI, Degano AL, Roth GA. Glutamate Release Machinery Is Altered in the Frontal Cortex of Rats with Experimental Autoimmune Encephalomyelitis. Mol Neurobiol 2014; 51:1353-67. [DOI: 10.1007/s12035-014-8814-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 07/11/2014] [Indexed: 01/30/2023]
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Phosphorylation of synapsin I by cyclin-dependent kinase-5 sets the ratio between the resting and recycling pools of synaptic vesicles at hippocampal synapses. J Neurosci 2014; 34:7266-80. [PMID: 24849359 DOI: 10.1523/jneurosci.3973-13.2014] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Cyclin-dependent kinase-5 (Cdk5) was reported to downscale neurotransmission by sequestering synaptic vesicles (SVs) in the release-reluctant resting pool, but the molecular targets mediating this activity remain unknown. Synapsin I (SynI), a major SV phosphoprotein involved in the regulation of SV trafficking and neurotransmitter release, is one of the presynaptic substrates of Cdk5, which phosphorylates it in its C-terminal region at Ser(549) (site 6) and Ser(551) (site 7). Here we demonstrate that Cdk5 phosphorylation of SynI fine tunes the recruitment of SVs to the active recycling pool and contributes to the Cdk5-mediated homeostatic responses. Phosphorylation of SynI by Cdk5 is physiologically regulated and enhances its binding to F-actin. The effects of Cdk5 inhibition on the size and depletion kinetics of the recycling pool, as well as on SV distribution within the nerve terminal, are virtually abolished in mouse SynI knock-out (KO) neurons or in KO neurons expressing the dephosphomimetic SynI mutants at sites 6,7 or site 7 only. The observation that the single site-7 mutant phenocopies the effects of the deletion of SynI identifies this site as the central switch in mediating the synaptic effects of Cdk5 and demonstrates that SynI is necessary and sufficient for achieving the effects of the kinase on SV trafficking. The phosphorylation state of SynI by Cdk5 at site 7 is regulated during chronic modification of neuronal activity and is an essential downstream effector for the Cdk5-mediated homeostatic scaling.
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Srivastava AK, Schwartz CE. Intellectual disability and autism spectrum disorders: causal genes and molecular mechanisms. Neurosci Biobehav Rev 2014; 46 Pt 2:161-74. [PMID: 24709068 DOI: 10.1016/j.neubiorev.2014.02.015] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 01/30/2014] [Accepted: 02/12/2014] [Indexed: 12/19/2022]
Abstract
Intellectual disability (ID) and autism spectrum disorder (ASD) are the most common developmental disorders present in humans. Combined, they affect between 3 and 5% of the population. Additionally, they can be found together in the same individual thereby complicating treatment. The causative factors (genes, epigenetic and environmental) are quite varied and likely interact so as to further complicate the assessment of an individual patient. Nonetheless, much valuable information has been gained by identifying candidate genes for ID or ASD. Understanding the etiology of either ID or ASD is of utmost importance for families. It allows a determination of the risk of recurrence, the possibility of other comorbidity medical problems, the molecular and cellular nature of the pathobiology and hopefully potential therapeutic approaches.
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Affiliation(s)
- Anand K Srivastava
- J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC, USA
| | - Charles E Schwartz
- J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC, USA.
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Imperlini E, Orrù S, Corbo C, Daniele A, Salvatore F. Altered brain protein expression profiles are associated with molecular neurological dysfunction in the PKU mouse model. J Neurochem 2014; 129:1002-12. [PMID: 24548049 PMCID: PMC4286000 DOI: 10.1111/jnc.12683] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 01/07/2014] [Accepted: 02/02/2014] [Indexed: 12/14/2022]
Abstract
Phenylketonuria (PKU), if not detected and treated in newborns, causes severe neurological dysfunction and cognitive and behavioral deficiencies. Despite the biochemical characterization of PKU, the molecular mechanisms underlying PKU-associated brain dysfunction remain poorly understood. The aim of this study was to gain insights into the pathogenesis of this neurological damage by analyzing protein expression profiles in brain tissue of Black and Tan BRachyury-PahEnu2 mice (a mouse model of PKU). We compared the cerebral protein expression of homozygous PKU mice with that of their heterozygous counterparts using two-dimensional difference gel electrophoresis analysis, and identified 21 differentially expressed proteins, four of which were over-expressed and 17 under-expressed. An in silico bioinformatic approach indicated that protein under-expression was related to neuronal differentiation and dendritic growth, and to such neurological disorders as progressive motor neuropathy and movement disorders. Moreover, functional annotation analyses showed that some identified proteins were involved in oxidative metabolism. To further investigate the proteins involved in the neurological damage, we validated two of the proteins that were most strikingly under-expressed, namely, Syn2 and Dpysl2, which are involved in synaptic function and neurotransmission. We found that Glu2/3 and NR1 receptor subunits were over-expressed in PKU mouse brain. Our results indicate that differential expression of these proteins may be associated with the processes underlying PKU brain dysfunction, namely, decreased synaptic plasticity and impaired neurotransmission.
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Kudryashova IV. Molecular mechanisms of short-term plasticity as a basis of frequency coding: The role of proteolytic systems. NEUROCHEM J+ 2014. [DOI: 10.1134/s1819712414010097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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37
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Abstract
Synaptic vesicle recycling is one of the best-studied cellular pathways. Many of the proteins involved are known, and their interactions are becoming increasingly clear. However, as for many other pathways, it is still difficult to understand synaptic vesicle recycling as a whole. While it is generally possible to point out how synaptic reactions take place, it is not always easy to understand what triggers or controls them. Also, it is often difficult to understand how the availability of the reaction partners is controlled: how the reaction partners manage to find each other in the right place, at the right time. I present here an overview of synaptic vesicle recycling, discussing the mechanisms that trigger different reactions, and those that ensure the availability of reaction partners. A central argument is that synaptic vesicles bind soluble cofactor proteins, with low affinity, and thus control their availability in the synapse, forming a buffer for cofactor proteins. The availability of cofactor proteins, in turn, regulates the different synaptic reactions. Similar mechanisms, in which one of the reaction partners buffers another, may apply to many other processes, from the biogenesis to the degradation of the synaptic vesicle.
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Affiliation(s)
- Silvio O Rizzoli
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen European Neuroscience Institute, Göttingen, Germany
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38
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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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Giannandrea M, Guarnieri FC, Gehring NH, Monzani E, Benfenati F, Kulozik AE, Valtorta F. Nonsense-mediated mRNA decay and loss-of-function of the protein underlie the X-linked epilepsy associated with the W356× mutation in synapsin I. PLoS One 2013; 8:e67724. [PMID: 23818987 PMCID: PMC3688603 DOI: 10.1371/journal.pone.0067724] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 05/21/2013] [Indexed: 11/22/2022] Open
Abstract
Synapsins are a family of neuronal phosphoproteins associated with the cytosolic surface of synaptic vesicles. Experimental evidence suggests a role for synapsins in synaptic vesicle clustering and recycling at the presynaptic terminal, as well as in neuronal development and synaptogenesis. Synapsin knock-out (Syn1(-/-) ) mice display an epileptic phenotype and mutations in the SYN1 gene have been identified in individuals affected by epilepsy and/or autism spectrum disorder. We investigated the impact of the c.1067G>A nonsense transition, the first mutation described in a family affected by X-linked syndromic epilepsy, on the expression and functional properties of the synapsin I protein. We found that the presence of a premature termination codon in the human SYN1 transcript renders it susceptible to nonsense-mediated mRNA decay (NMD). Given that the NMD efficiency is highly variable among individuals and cell types, we investigated also the effects of expression of the mutant protein and found that it is expressed at lower levels compared to wild-type synapsin I, forms perinuclear aggregates and is unable to reach presynaptic terminals in mature hippocampal neurons grown in culture. Taken together, these data indicate that in patients carrying the W356× mutation the function of synapsin I is markedly impaired, due to both the strongly decreased translation and the altered function of the NMD-escaped protein, and support the value of Syn1(-/-) mice as an experimental model mimicking the human pathology.
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MESH Headings
- Animals
- Blotting, Northern
- Cells, Cultured
- Codon, Nonsense
- Epilepsy/genetics
- Epilepsy/metabolism
- Female
- Gene Expression
- Genetic Diseases, X-Linked/genetics
- Genetic Diseases, X-Linked/metabolism
- HeLa Cells
- Hippocampus/cytology
- Hippocampus/metabolism
- Humans
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microscopy, Fluorescence
- Microtubule-Associated Proteins/metabolism
- Neurons/metabolism
- Nonsense Mediated mRNA Decay
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Synapsins/genetics
- Synapsins/metabolism
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Affiliation(s)
- Maila Giannandrea
- Division of Neuroscience, San Raffaele Scientific Institute and Vita-Salute University, Milan, Italy
| | - Fabrizia C. Guarnieri
- Division of Neuroscience, San Raffaele Scientific Institute and Vita-Salute University, Milan, Italy
| | | | - Elena Monzani
- Division of Neuroscience, San Raffaele Scientific Institute and Vita-Salute University, Milan, Italy
| | - Fabio Benfenati
- Department of Neuroscience and Brain Technologies, The Italian Institute of Technology, Genoa, Italy
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Andreas E. Kulozik
- Department of Pediatric Oncology, Hematology and Immunology, University of Heidelberg Medical Center and Molecular Medicine Partnership Unit, EMBL and University of Heidelberg, Heidelberg, Germany
| | - Flavia Valtorta
- Division of Neuroscience, San Raffaele Scientific Institute and Vita-Salute University, Milan, Italy
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Staras K, Mikulincer D, Gitler D. Monitoring and quantifying dynamic physiological processes in live neurons using fluorescence recovery after photobleaching. J Neurochem 2013; 126:213-22. [PMID: 23496032 DOI: 10.1111/jnc.12240] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 03/12/2013] [Accepted: 03/13/2013] [Indexed: 12/27/2022]
Abstract
The direct visualization of subcellular dynamic processes is often hampered by limitations in the resolving power achievable with conventional microscopy techniques. Fluorescence recovery after photobleaching has emerged as a highly informative approach to address this challenge, permitting the quantitative measurement of the movement of small organelles and proteins in living functioning cells, and offering detailed insights into fundamental cellular phenomena of physiological importance. In recent years, its implementation has benefited from the increasing availability of confocal microscopy systems and of powerful labeling techniques based on genetically encoded fluorescent proteins or other chemical markers. In this review, we present fluorescence recovery after photobleaching and related techniques in the context of contemporary neurobiological research and discuss quantitative and semi-quantitative approaches to their interpretation.
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Affiliation(s)
- Kevin Staras
- School of Life Sciences, University of Sussex, Brighton, UK
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41
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Siksou L, Silm K, Biesemann C, Nehring RB, Wojcik SM, Triller A, El Mestikawy S, Marty S, Herzog E. A role for vesicular glutamate transporter 1 in synaptic vesicle clustering and mobility. Eur J Neurosci 2013; 37:1631-42. [DOI: 10.1111/ejn.12199] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 02/20/2013] [Accepted: 02/21/2013] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - Christoph Biesemann
- Department of Molecular Neurobiology; Max Planck Institute of Experimental Medicine; Goettingen; Germany
| | - Ralf B. Nehring
- Department of Molecular and Human Genetics; Baylor College of Medicine; Houston; TX; USA
| | - Sonja M. Wojcik
- Department of Molecular Neurobiology; Max Planck Institute of Experimental Medicine; Goettingen; Germany
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Giachello CNG, Premoselli F, Montarolo PG, Ghirardi M. Pentylenetetrazol-induced epileptiform activity affects basal synaptic transmission and short-term plasticity in monosynaptic connections. PLoS One 2013; 8:e56968. [PMID: 23437283 PMCID: PMC3577694 DOI: 10.1371/journal.pone.0056968] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2012] [Accepted: 01/18/2013] [Indexed: 11/18/2022] Open
Abstract
Epileptic activity is generally induced in experimental models by local application of epileptogenic drugs, including pentylenetetrazol (PTZ), widely used on both vertebrate and invertebrate neurons. Despite the high prevalence of this neurological disorder and the extensive research on it, the cellular and molecular mechanisms underlying epileptogenesis still remain unclear. In this work, we examined PTZ-induced neuronal changes in Helix monosynaptic circuits formed in vitro, as a simpler experimental model to investigate the effects of epileptiform activity on both basal release and post-tetanic potentiation (PTP), a form of short-term plasticity. We observed a significant enhancement of basal synaptic strength, with kinetics resembling those of previously described use-dependent forms of plasticity, determined by changes in estimated quantal parameters, such as the readily releasable pool and the release probability. Moreover, these neurons exhibited a strong reduction in PTP expression and in its decay time constant, suggesting an impairment in the dynamic reorganization of synaptic vesicle pools following prolonged stimulation of synaptic transmission. In order to explain this imbalance, we determined whether epileptic activity is related to the phosphorylation level of synapsin, which is known to modulate synaptic plasticity. Using western blot and immunocytochemical staining we found a PTZ-dependent increase in synapsin phosphorylation at both PKA/CaMKI/IV and MAPK/Erk sites, both of which are important for modulating synaptic plasticity. Taken together, our findings suggest that prolonged epileptiform activity leads to an increase in the synapsin phosphorylation status, thereby contributing to an alteration of synaptic strength in both basal condition and tetanus-induced potentiation.
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Lignani G, Raimondi A, Ferrea E, Rocchi A, Paonessa F, Cesca F, Orlando M, Tkatch T, Valtorta F, Cossette P, Baldelli P, Benfenati F. Epileptogenic Q555X SYN1 mutant triggers imbalances in release dynamics and short-term plasticity. Hum Mol Genet 2013; 22:2186-99. [PMID: 23406870 PMCID: PMC3652419 DOI: 10.1093/hmg/ddt071] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Synapsin I (SynI) is a synaptic vesicle (SV) phosphoprotein playing multiple roles in synaptic transmission and plasticity by differentially affecting crucial steps of SV trafficking in excitatory and inhibitory synapses. SynI knockout (KO) mice are epileptic, and nonsense and missense mutations in the human SYN1 gene have a causal role in idiopathic epilepsy and autism. To get insights into the mechanisms of epileptogenesis linked to SYN1 mutations, we analyzed the effects of the recently identified Q555X mutation on neurotransmitter release dynamics and short-term plasticity (STP) in excitatory and inhibitory synapses. We used patch-clamp electrophysiology coupled to electron microscopy and multi-electrode arrays to dissect synaptic transmission of primary SynI KO hippocampal neurons in which the human wild-type and mutant SynI were expressed by lentiviral transduction. A parallel decrease in the SV readily releasable pool in inhibitory synapses and in the release probability in excitatory synapses caused a marked reduction in the evoked synchronous release. This effect was accompanied by an increase in asynchronous release that was much more intense in excitatory synapses and associated with an increased total charge transfer. Q555X-hSynI induced larger facilitation and post-tetanic potentiation in excitatory synapses and stronger depression after long trains in inhibitory synapses. These changes were associated with higher network excitability and firing/bursting activity. Our data indicate that imbalances in STP and release dynamics of inhibitory and excitatory synapses trigger network hyperexcitability potentially leading to epilepsy/autism manifestations.
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Affiliation(s)
- Gabriele Lignani
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Via Morego 30, Genova 16163, Italy
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