1
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Coupland CE, Karimi R, Bueler SA, Liang Y, Courbon GM, Di Trani JM, Wong CJ, Saghian R, Youn JY, Wang LY, Rubinstein JL. High-resolution electron cryomicroscopy of V-ATPase in native synaptic vesicles. Science 2024:eadp5577. [PMID: 38900912 DOI: 10.1126/science.adp5577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Accepted: 05/16/2024] [Indexed: 06/22/2024]
Abstract
Intercellular communication in the nervous system occurs through the release of neurotransmitters into the synaptic cleft between neurons. In the presynaptic neuron, the proton pumping vesicular- or vacuolar-type ATPase (V-ATPase) powers neurotransmitter loading into synaptic vesicles (SVs), with the V1 complex dissociating from the membrane region of the enzyme before exocytosis. We isolated SVs from rat brain using SidK, a V-ATPase-binding bacterial effector protein. Single particle electron cryomicroscopy allowed high-resolution structure determination of V-ATPase within the native SV membrane. In the structure, regularly spaced cholesterol molecules decorate the enzyme's rotor and the abundant SV protein synaptophysin binds the complex stoichiometrically. ATP hydrolysis during vesicle loading results in loss of V1 from the SV membrane, suggesting that loading is sufficient to induce dissociation of the enzyme.
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Affiliation(s)
- Claire E Coupland
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Canada M5G 1X8
| | - Ryan Karimi
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Canada M5G 1X8
- Department of Medical Biophysics, The University of Toronto, Toronto, Canada M5G 1L7
| | - Stephanie A Bueler
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Canada M5G 1X8
| | - Yingke Liang
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Canada M5G 1X8
- Department of Biochemistry, The University of Toronto, Toronto, Canada M5S 1A8
| | - Gautier M Courbon
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Canada M5G 1X8
- Department of Medical Biophysics, The University of Toronto, Toronto, Canada M5G 1L7
| | - Justin M Di Trani
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Canada M5G 1X8
| | | | - Rayan Saghian
- Neuroscience and Mental Health Program, The Hospital for Sick Children, Toronto, Canada M5G 1X8
- Department of Physiology, The University of Toronto, Toronto, Canada M5S 1A8
| | - Ji-Young Youn
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Canada M5G 1X8
- Cell Biology Program, The Hospital for Sick Children, Toronto, Canada M5G 1X8
- Department of Molecular Genetics, The University of Toronto, Toronto, Canada M5S 1A8
| | - Lu-Yang Wang
- Neuroscience and Mental Health Program, The Hospital for Sick Children, Toronto, Canada M5G 1X8
- Department of Physiology, The University of Toronto, Toronto, Canada M5S 1A8
| | - John L Rubinstein
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Canada M5G 1X8
- Department of Medical Biophysics, The University of Toronto, Toronto, Canada M5G 1L7
- Department of Biochemistry, The University of Toronto, Toronto, Canada M5S 1A8
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2
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Bera M, Radhakrishnan A, Coleman J, K. Sundaram RV, Ramakrishnan S, Pincet F, Rothman JE. Synaptophysin chaperones the assembly of 12 SNAREpins under each ready-release vesicle. Proc Natl Acad Sci U S A 2023; 120:e2311484120. [PMID: 37903271 PMCID: PMC10636311 DOI: 10.1073/pnas.2311484120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 09/19/2023] [Indexed: 11/01/2023] Open
Abstract
The synaptic vesicle protein Synaptophysin (Syp) has long been known to form a complex with the Vesicle associated soluble N-ethylmaleimide sensitive fusion protein attachment receptor (v-SNARE) Vesicle associated membrane protein (VAMP), but a more specific molecular function or mechanism of action in exocytosis has been lacking because gene knockouts have minimal effects. Utilizing fully defined reconstitution and single-molecule measurements, we now report that Syp functions as a chaperone that determines the number of SNAREpins assembling between a ready-release vesicle and its target membrane bilayer. Specifically, Syp directs the assembly of 12 ± 1 SNAREpins under each docked vesicle, even in the face of an excess of SNARE proteins. The SNAREpins assemble in successive waves of 6 ± 1 and 5 ± 2 SNAREpins, respectively, tightly linked to oligomerization of and binding to the vesicle Ca++ sensor Synaptotagmin. Templating of 12 SNAREpins by Syp is likely the direct result of its hexamer structure and its binding of VAMP2 dimers, both of which we demonstrate in detergent extracts and lipid bilayers.
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Affiliation(s)
- Manindra Bera
- Nanobiology Institute, Yale University School of Medicine, New Haven, CT06520
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT06520
| | - Abhijith Radhakrishnan
- Nanobiology Institute, Yale University School of Medicine, New Haven, CT06520
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT06520
| | - Jeff Coleman
- Nanobiology Institute, Yale University School of Medicine, New Haven, CT06520
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT06520
| | - R. Venkat K. Sundaram
- Nanobiology Institute, Yale University School of Medicine, New Haven, CT06520
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT06520
| | - Sathish Ramakrishnan
- Nanobiology Institute, Yale University School of Medicine, New Haven, CT06520
- Department of Pathology, Yale University School of Medicine, New Haven, CT06520
| | - Frederic Pincet
- Nanobiology Institute, Yale University School of Medicine, New Haven, CT06520
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT06520
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, Paris Sciences et Lettres Research University, CNRS, Sorbonne Université, Université de Paris Cité, 75005Paris, France
| | - James E. Rothman
- Nanobiology Institute, Yale University School of Medicine, New Haven, CT06520
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT06520
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3
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Bera M, Radhakrishnan A, Coleman J, Sundaram RVK, Ramakrishnan S, Pincet F, Rothman JE. Synaptophysin Chaperones the Assembly of 12 SNAREpins under each Ready-Release Vesicle. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.05.547834. [PMID: 37461465 PMCID: PMC10349951 DOI: 10.1101/2023.07.05.547834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/24/2023]
Abstract
The synaptic vesicle protein Synaptophysin has long been known to form a complex with the v-SNARE VAMP, but a more specific molecular function or mechanism of action in exocytosis has been lacking because gene knockouts have minimal effects. Utilizing fully-defined reconstitution and single-molecule measurements, we now report that Synaptophysin functions as a chaperone that determines the number of SNAREpins assembling between a ready-release vesicle and its target membrane bilayer. Specifically, Synaptophysin directs the assembly of 12 ± 1 SNAREpins under each docked vesicle, even in the face of an excess of SNARE proteins. The SNAREpins assemble in successive waves of 6 ± 1 and 5 ± 2 SNAREpins, respectively, tightly linked to oligomerization of and binding to the vesicle Ca++ sensor Synaptotagmin. Templating of 12 SNAREpins by Synaptophysin is likely the direct result of its hexamer structure and its binding of VAMP2 dimers, both of which we demonstrate in detergent extracts and lipid bilayers.
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Affiliation(s)
- Manindra Bera
- Nanobiology Institute, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Abhijith Radhakrishnan
- Nanobiology Institute, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Jeff Coleman
- Nanobiology Institute, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Ramalingam Venkat Kalyana Sundaram
- Nanobiology Institute, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Sathish Ramakrishnan
- Nanobiology Institute, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Pathology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Frederic Pincet
- Nanobiology Institute, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA
- Laboratoire de Physique de l’Ecole normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France
| | - James E. Rothman
- Nanobiology Institute, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA
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4
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Squizani S, Jantsch J, Rodrigues FDS, Braga MF, Eller S, de Oliveira TF, Silveira AK, Moreira JCF, Giovenardi M, Porawski M, Guedes RP. Zinc Supplementation Partially Decreases the Harmful Effects of a Cafeteria Diet in Rats but Does Not Prevent Intestinal Dysbiosis. Nutrients 2022; 14:3921. [PMID: 36235574 PMCID: PMC9571896 DOI: 10.3390/nu14193921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 09/13/2022] [Accepted: 09/15/2022] [Indexed: 11/21/2022] Open
Abstract
Zinc (Zn) plays an important role in metabolic homeostasis and may modulate neurological impairment related to obesity. The present study aimed to evaluate the effect of Zn supplementation on the intestinal microbiota, fatty acid profile, and neurofunctional parameters in obese male Wistar rats. Rats were fed a cafeteria diet (CAF), composed of ultra-processed and highly caloric and palatable foods, for 20 weeks to induce obesity. From week 16, Zn supplementation was started (10 mg/kg/day). At the end of the experiment, we evaluated the colon morphology, composition of gut microbiota, intestinal fatty acids, integrity of the intestinal barrier and blood-brain barrier (BBB), and neuroplasticity markers in the cerebral cortex and hippocampus. Obese rats showed dysbiosis, morphological changes, short-chain fatty acid (SCFA) reduction, and increased saturated fatty acids in the colon. BBB may also be compromised in CAF-fed animals, as claudin-5 expression is reduced in the cerebral cortex. In addition, synaptophysin was decreased in the hippocampus, which may affect synaptic function. Our findings showed that Zn could not protect obese animals from intestinal dysbiosis. However, an increase in acetate levels was observed, which suggests a partial beneficial effect of Zn. Thus, Zn supplementation may not be sufficient to protect from obesity-related dysfunctions.
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Affiliation(s)
- Samia Squizani
- Programa de Pós-Graduação em Biociências, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre 90050-170, Brazil
| | - Jeferson Jantsch
- Programa de Pós-Graduação em Biociências, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre 90050-170, Brazil
| | - Fernanda da Silva Rodrigues
- Programa de Pós-Graduação em Biociências, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre 90050-170, Brazil
| | - Matheus Filipe Braga
- Acadêmico do Curso de Biomedicina, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre 90050-170, Brazil
| | - Sarah Eller
- Programa de Pós-Graduação em Ciências da Saúde, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre 90050-170, Brazil
| | - Tiago Franco de Oliveira
- Programa de Pós-Graduação em Ciências da Saúde, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre 90050-170, Brazil
| | - Alexandre Kleber Silveira
- Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre 90035-003, Brazil
| | - José Cláudio Fonseca Moreira
- Programa de Pós-Graduação em Biociências, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre 90050-170, Brazil
- Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre 90035-003, Brazil
| | - Marcia Giovenardi
- Programa de Pós-Graduação em Biociências, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre 90050-170, Brazil
- Programa de Pós-Graduação em Ciências da Saúde, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre 90050-170, Brazil
| | - Marilene Porawski
- Programa de Pós-Graduação em Biociências, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre 90050-170, Brazil
- Programa de Pós-Graduação em Medicina: Hepatologia, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre 90050-170, Brazil
| | - Renata Padilha Guedes
- Programa de Pós-Graduação em Biociências, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre 90050-170, Brazil
- Programa de Pós-Graduação em Ciências da Saúde, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre 90050-170, Brazil
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5
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Goel N, Dhiman K, Kalidas N, Mukhopadhyay A, Ashish F, Bhattacharjee S. Plasmodium falciparum
Kelch13 and its artemisinin‐resistant mutants assemble as hexamers in solution: a SAXS data‐driven modelling study. FEBS J 2022; 289:4935-4962. [DOI: 10.1111/febs.16378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 01/11/2022] [Accepted: 01/26/2022] [Indexed: 10/19/2022]
Affiliation(s)
- Nainy Goel
- Special Centre for Molecular Medicine Jawaharlal Nehru University New Delhi India
| | - Kanika Dhiman
- Council of Scientific and Industrial Research‐Institute of Microbial Technology Chandigarh India
| | - Nidhi Kalidas
- Council of Scientific and Industrial Research‐Institute of Microbial Technology Chandigarh India
| | - Anwesha Mukhopadhyay
- Special Centre for Molecular Medicine Jawaharlal Nehru University New Delhi India
| | - Fnu Ashish
- Council of Scientific and Industrial Research‐Institute of Microbial Technology Chandigarh India
| | - Souvik Bhattacharjee
- Special Centre for Molecular Medicine Jawaharlal Nehru University New Delhi India
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6
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Rehman MU, Ghazanfar S, Ul Haq R, Ullah S, Khan S, Wu J, Ahmad W, Tipu MK. Probiotics (Bacillus clausii and Lactobacillus fermentum NMCC-14) Ameliorate Stress Behavior in Mice by Increasing Monoamine Levels and mRNA Expression of Dopamine Receptors (D1 and D2) and Synaptophysin. Front Pharmacol 2022; 13:915595. [PMID: 35928261 PMCID: PMC9343877 DOI: 10.3389/fphar.2022.915595] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 05/30/2022] [Indexed: 11/13/2022] Open
Abstract
Stress is a physiological consequence of the body to adversity. The gut–brain axis and probiotics are gaining interest to provide better treatment for stress and other neurological disorders. Probiotic (Lactobacillus fermentum NMCC-14 and Bacillus clausii, 1010 colony-forming unit/day/animal, per oral) effects were investigated in acute (up to day 7) and subacute (days 8–14) restraint-stressed and normal mice through behavioral paradigms (elevated plus maze: EPM, light dark box/dark light box: LDB, and open field test: OFT). Time spent in the open arms of the EPM, time spent in the light compartment of the LDB, and movable time and time spent in the center of the OFT were significantly (p ≤ 0.05, n = 5) increased in probiotic-treated restraint-stressed mice. Enzyme-linked immunoassay determined blood cortisol and adrenocorticotropic hormone (ACTH) levels, which were reduced significantly (p < 0.05, n = 5) in probiotic-treated restraint-stressed mice. Hematoxylin and eosin-stained hippocampal slides also showed less or no neurodegeneration in the probiotic-treated animals. High-performance liquid chromatography and quantitative polymerase chain reaction were performed to determine the monoamine levels and mRNA expression of dopamine receptor subtypes (D1 and D2) and synaptophysin in the mice hippocampus (HC) and prefrontal cortex (PFC). The dopamine, serotonin, and norepinephrine levels were also significantly (p < 0.05, n = 5) increased in the HC and PFC of probiotic-treated animal brains. Fold expression of mRNA of D1 and D2 (except HC, LF-S, day 14) receptors and synaptophysin was also significantly (p < 0.05, n = 5) increased in the same brain parts of probiotic-treated restraint-stressed mice. Comparing mice in the Lactobacillus fermentum NMCC-14 and Bacillus clausii groups to mice in the normal group, only a significant (p < 0.05, n = 5) decrease was observed in the serum ACTH and cortisol levels on day 14 in Bacillus clausii-treated mice, where all other parameters also showed improvement. In comparison, Bacillus clausii showed greater stress suppressant activity than Lactobacillus fermentum NMCC-14. However, both probiotic bacteria can be a better and safer therapeutic alternative for ailments than currently available drugs.
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Affiliation(s)
- Mujeeb Ur Rehman
- Department of Pharmacy, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Shakira Ghazanfar
- National Institute for Genomics and Advanced Biotechnology (NIGAB), National Agricultural Research Centre (NARC), Islamabad, Pakistan
| | - Rizwan Ul Haq
- Department of Pharmacy, Abbottabad University of Science & Technology, Abbottabad KPK, Pakistan
| | - Shakir Ullah
- Institute of Basic Medical Sciences, Khyber Medical University, Peshawar KPK, Pakistan
| | - Salman Khan
- Department of Pharmacy, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Jianbo Wu
- Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Diseases of Sichuan Province, Drug Discovery and Functional Food Laboratory, Southwest Medical University, Luzhou, China
- Laboratory for Cardiovascular Pharmacology, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, China
| | - Waqar Ahmad
- Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Diseases of Sichuan Province, Drug Discovery and Functional Food Laboratory, Southwest Medical University, Luzhou, China
- Laboratory for Cardiovascular Pharmacology, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, China
- *Correspondence: Muhammad Khalid Tipu, ; Waqar Ahmad,
| | - Muhammad Khalid Tipu
- Department of Pharmacy, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
- *Correspondence: Muhammad Khalid Tipu, ; Waqar Ahmad,
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7
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Fei X, Dou YN, Lv W, Ding B, Wei J, Wu X, He X, Fei Z, Fei F. TLR4 deletion improves cognitive brain function and structure in aged mice. Neuroscience 2022; 492:1-17. [DOI: 10.1016/j.neuroscience.2022.04.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 04/01/2022] [Accepted: 04/04/2022] [Indexed: 11/25/2022]
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8
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Cousin MA. Synaptophysin-dependent synaptobrevin-2 trafficking at the presynapse-Mechanism and function. J Neurochem 2021; 159:78-89. [PMID: 34468992 DOI: 10.1111/jnc.15499] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 08/26/2021] [Accepted: 08/28/2021] [Indexed: 12/30/2022]
Abstract
Synaptobrevin-2 (Syb2) is a soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) that is essential for neurotransmitter release. It is the most numerous protein on a synaptic vesicle (SV) and drives SV fusion via interactions with its cognate SNARE partners on the presynaptic plasma membrane. Synaptophysin (Syp) is the second most abundant protein on SVs; however, in contrast to Syb2, it has no obligatory role in neurotransmission. Syp interacts with Syb2 on SVs, and the molecular nature of its interaction with Syb2 and its physiological role has been debated for decades. However, recent studies have revealed that the sole physiological role of Syp at the presynapse is to ensure the efficient retrieval of Syb2 during SV endocytosis. In this review, current theories surrounding the role of Syp in Syb2 trafficking will be discussed, in addition to the debate regarding the molecular nature of their interaction. A unifying model is presented that describes how Syp controls Syb2 function as part of an integrated mechanism involving key molecular players such as intersectin-1 and AP180/CALM. Finally, key future questions surrounding the role of Syp-dependent Syb2 trafficking will be posed, with respect to brain function in health and disease.
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Affiliation(s)
- Michael A Cousin
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland, UK.,Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, Scotland, UK.,Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, Scotland, UK
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9
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White DN, Stowell MHB. Room for Two: The Synaptophysin/Synaptobrevin Complex. Front Synaptic Neurosci 2021; 13:740318. [PMID: 34616284 PMCID: PMC8488437 DOI: 10.3389/fnsyn.2021.740318] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 08/18/2021] [Indexed: 12/01/2022] Open
Abstract
Synaptic vesicle release is regulated by upwards of 30 proteins at the fusion complex alone, but disruptions in any one of these components can have devastating consequences for neuronal communication. Aberrant molecular responses to calcium signaling at the pre-synaptic terminal dramatically affect vesicle trafficking, docking, fusion, and release. At the organismal level, this is reflected in disorders such as epilepsy, depression, and neurodegeneration. Among the myriad pre-synaptic proteins, perhaps the most functionally mysterious is synaptophysin (SYP). On its own, this vesicular transmembrane protein has been proposed to function as a calcium sensor, a cholesterol-binding protein, and to form ion channels across the phospholipid bilayer. The downstream effects of these functions are largely unknown. The physiological relevance of SYP is readily apparent in its interaction with synaptobrevin (VAMP2), an integral element of the neuronal SNARE complex. SNAREs, soluble NSF attachment protein receptors, comprise a family of proteins essential for vesicle fusion. The complex formed by SYP and VAMP2 is thought to be involved in both trafficking to the pre-synaptic membrane as well as regulation of SNARE complex formation. Recent structural observations specifically implicate the SYP/VAMP2 complex in anchoring the SNARE assembly at the pre-synaptic membrane prior to vesicle fusion. Thus, the SYP/VAMP2 complex appears vital to the form and function of neuronal exocytotic machinery.
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Affiliation(s)
- Dustin N. White
- MCD Biology, University of Colorado Boulder, Boulder, CO, United States
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10
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Bhattacharya U, Jhou JF, Zou YF, Abrigo G, Lin SW, Chen YH, Chien FC, Tai HC. Surface charge manipulation and electrostatic immobilization of synaptosomes for super-resolution imaging: a study on tau compartmentalization. Sci Rep 2021; 11:18583. [PMID: 34545174 PMCID: PMC8452691 DOI: 10.1038/s41598-021-98142-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 07/30/2021] [Indexed: 12/31/2022] Open
Abstract
Synaptosomes are subcellular fractions prepared from brain tissues that are enriched in synaptic terminals, widely used for the study of neural transmission and synaptic dysfunction. Immunofluorescence imaging is increasingly applied to synaptosomes to investigate protein localization. However, conventional methods for imaging synaptosomes over glass coverslips suffer from formaldehyde-induced aggregation. Here, we developed a facile strategy to capture and image synaptosomes without aggregation artefacts. First, ethylene glycol bis(succinimidyl succinate) (EGS) is chosen as the chemical fixative to replace formaldehyde. EGS/glycine treatment makes the zeta potential of synaptosomes more negative. Second, we modified glass coverslips with 3-aminopropyltriethoxysilane (APTES) to impart positive charges. EGS-fixed synaptosomes spontaneously attach to modified glasses via electrostatic attraction while maintaining good dispersion. Individual synaptic terminals are imaged by conventional fluorescence microscopy or by super-resolution techniques such as direct stochastic optical reconstruction microscopy (dSTORM). We examined tau protein by two-color and three-color dSTORM to understand its spatial distribution within mouse cortical synapses, observing tau colocalization with synaptic vesicles as well postsynaptic densities.
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Affiliation(s)
| | - Jia-Fong Jhou
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan
| | - Yi-Fong Zou
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan
| | - Gerald Abrigo
- Department of Optics and Photonics, National Central University, Taoyuan, Taiwan
| | - Shu-Wei Lin
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan
| | - Yun-Hsuan Chen
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan
| | - Fan-Ching Chien
- Department of Optics and Photonics, National Central University, Taoyuan, Taiwan
| | - Hwan-Ching Tai
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan.
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11
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Kim G, Lee SE, Jeong S, Lee J, Park D, Chang S. Multivalent electrostatic pi-cation interaction between synaptophysin and synapsin is responsible for the coacervation. Mol Brain 2021; 14:137. [PMID: 34496937 PMCID: PMC8424992 DOI: 10.1186/s13041-021-00846-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/24/2021] [Indexed: 12/26/2022] Open
Abstract
We recently showed that synaptophysin (Syph) and synapsin (Syn) can induce liquid-liquid phase separation (LLPS) to cluster small synaptic-like microvesicles in living cells which are highly reminiscent of SV cluster. However, as there is no physical interaction between them, the underlying mechanism for their coacervation remains unknown. Here, we showed that the coacervation between Syph and Syn is primarily governed by multivalent pi-cation electrostatic interactions among tyrosine residues of Syph C-terminal (Ct) and positively charged Syn. We found that Syph Ct is intrinsically disordered and it alone can form liquid droplets by interactions among themselves at high concentration in a crowding environment in vitro or when assisted by additional interactions by tagging with light-sensitive CRY2PHR or subunits of a multimeric protein in living cells. Syph Ct contains 10 repeated sequences, 9 of them start with tyrosine, and mutating 9 tyrosine to serine (9YS) completely abolished the phase separating property of Syph Ct, indicating tyrosine-mediated pi-interactions are critical. We further found that 9YS mutation failed to coacervate with Syn, and since 9YS retains Syph's negative charge, the results indicate that pi-cation interactions rather than simple charge interactions are responsible for their coacervation. In addition to revealing the underlying mechanism of Syph and Syn coacervation, our results also raise the possibility that physiological regulation of pi-cation interactions between Syph and Syn during synaptic activity may contribute to the dynamics of synaptic vesicle clustering.
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Affiliation(s)
- Goeun Kim
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Sang-Eun Lee
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, South Korea
- UK Dementia Research Institute, University College London, Cruciform Building, Gower St, London, WC1E 6BT, UK
| | - Seonyoung Jeong
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Jeongkun Lee
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Daehun Park
- Departments of Neuroscience and Cell Biology, Howard Hughes Medical Institute, 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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12
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Rubio-Ramos A, Labat-de-Hoz L, Correas I, Alonso MA. The MAL Protein, an Integral Component of Specialized Membranes, in Normal Cells and Cancer. Cells 2021; 10:1065. [PMID: 33946345 PMCID: PMC8145151 DOI: 10.3390/cells10051065] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 12/12/2022] Open
Abstract
The MAL gene encodes a 17-kDa protein containing four putative transmembrane segments whose expression is restricted to human T cells, polarized epithelial cells and myelin-forming cells. The MAL protein has two unusual biochemical features. First, it has lipid-like properties that qualify it as a member of the group of proteolipid proteins. Second, it partitions selectively into detergent-insoluble membranes, which are known to be enriched in condensed cell membranes, consistent with MAL being distributed in highly ordered membranes in the cell. Since its original description more than thirty years ago, a large body of evidence has accumulated supporting a role of MAL in specialized membranes in all the cell types in which it is expressed. Here, we review the structure, expression and biochemical characteristics of MAL, and discuss the association of MAL with raft membranes and the function of MAL in polarized epithelial cells, T lymphocytes, and myelin-forming cells. The evidence that MAL is a putative receptor of the epsilon toxin of Clostridium perfringens, the expression of MAL in lymphomas, the hypermethylation of the MAL gene and subsequent loss of MAL expression in carcinomas are also presented. We propose a model of MAL as the organizer of specialized condensed membranes to make them functional, discuss the role of MAL as a tumor suppressor in carcinomas, consider its potential use as a cancer biomarker, and summarize the directions for future research.
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Affiliation(s)
- Armando Rubio-Ramos
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.R.-R.); (L.L.-d.-H.); (I.C.)
| | - Leticia Labat-de-Hoz
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.R.-R.); (L.L.-d.-H.); (I.C.)
| | - Isabel Correas
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.R.-R.); (L.L.-d.-H.); (I.C.)
- Department of Molecular Biology, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Miguel A. Alonso
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.R.-R.); (L.L.-d.-H.); (I.C.)
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13
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Thomson AC, Schuhmann T, de Graaf TA, Sack AT, Rutten BPF, Kenis G. The Effects of Serum Removal on Gene Expression and Morphological Plasticity Markers in Differentiated SH-SY5Y Cells. Cell Mol Neurobiol 2021; 42:1829-1839. [PMID: 33656634 PMCID: PMC9239930 DOI: 10.1007/s10571-021-01062-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 02/12/2021] [Indexed: 11/06/2022]
Abstract
Despite the widespread use of the SH-SY5Y human neuroblastoma cell line in modeling human neurons in vitro, protocols for growth, differentiation and experimentation differ considerably across the literature. Many studies fully differentiate SH-SY5Y cells before experimentation, to investigate plasticity measures in a mature, human neuronal-like cell model. Prior to experimentation, serum is often removed from cell culture media, to arrest the cell growth cycle and synchronize cells. However, the exact effect of this serum removal before experimentation on mature, differentiated SH-SY5Y cells has not yet been described. In studies using differentiated SH-SY5Y cells, any effect of serum removal on plasticity markers may influence results. The aim of the current study was to systematically characterize, in differentiated, neuronal-like SH-SY5Y cells, the potentially confounding effects of complete serum removal in terms of morphological and gene expression markers of plasticity. We measured changes in commonly used morphological markers and in genes related to neuroplasticity and synaptogenesis, particularly in the BDNF-TrkB signaling pathway. We found that complete serum removal from already differentiated SH-SY5Y cells increases neurite length, neurite branching, and the proportion of cells with a primary neurite, as well as proportion of βIII-Tubulin and MAP2 expressing cells. Gene expression results also indicate increased expression of PSD95 and NTRK2 expression 24 h after serum removal. We conclude that serum deprivation in differentiated SH-SY5Y cells affects morphology and gene expression and can potentially confound plasticity-related outcome measures, having significant implications for experimental design in studies using differentiated SH-SY5Y cells as a model of human neurons.
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Affiliation(s)
- Alix C Thomson
- Section Brain Stimulation and Cognition, Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Oxfordlaan 55, Maastricht, The Netherlands. .,Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNS), Brain+Nerve Centre, Maastricht University Medical Centre+ (MUMC+), Maastricht, The Netherlands. .,Maastricht Brain Imaging Centre (MBIC), Maastricht University, Maastricht, The Netherlands. .,Centre for Integrative Neuroscience, Faculty of Psychology and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands.
| | - Teresa Schuhmann
- Section Brain Stimulation and Cognition, Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Oxfordlaan 55, Maastricht, The Netherlands.,Maastricht Brain Imaging Centre (MBIC), Maastricht University, Maastricht, The Netherlands.,Centre for Integrative Neuroscience, Faculty of Psychology and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - Tom A de Graaf
- Section Brain Stimulation and Cognition, Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Oxfordlaan 55, Maastricht, The Netherlands.,Maastricht Brain Imaging Centre (MBIC), Maastricht University, Maastricht, The Netherlands.,Centre for Integrative Neuroscience, Faculty of Psychology and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - Alexander T Sack
- Section Brain Stimulation and Cognition, Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Oxfordlaan 55, Maastricht, The Netherlands.,Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNS), Brain+Nerve Centre, Maastricht University Medical Centre+ (MUMC+), Maastricht, The Netherlands.,Maastricht Brain Imaging Centre (MBIC), Maastricht University, Maastricht, The Netherlands.,Centre for Integrative Neuroscience, Faculty of Psychology and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - Bart P F Rutten
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNS), Brain+Nerve Centre, Maastricht University Medical Centre+ (MUMC+), Maastricht, The Netherlands.,Centre for Integrative Neuroscience, Faculty of Psychology and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - Gunter Kenis
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNS), Brain+Nerve Centre, Maastricht University Medical Centre+ (MUMC+), Maastricht, The Netherlands.,Centre for Integrative Neuroscience, Faculty of Psychology and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands
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14
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Wittig S, Ganzella M, Barth M, Kostmann S, Riedel D, Pérez-Lara Á, Jahn R, Schmidt C. Cross-linking mass spectrometry uncovers protein interactions and functional assemblies in synaptic vesicle membranes. Nat Commun 2021; 12:858. [PMID: 33558502 PMCID: PMC7870876 DOI: 10.1038/s41467-021-21102-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 12/18/2020] [Indexed: 02/08/2023] Open
Abstract
Synaptic vesicles are storage organelles for neurotransmitters. They pass through a trafficking cycle and fuse with the pre-synaptic membrane when an action potential arrives at the nerve terminal. While molecular components and biophysical parameters of synaptic vesicles have been determined, our knowledge on the protein interactions in their membranes is limited. Here, we apply cross-linking mass spectrometry to study interactions of synaptic vesicle proteins in an unbiased approach without the need for specific antibodies or detergent-solubilisation. Our large-scale analysis delivers a protein network of vesicle sub-populations and functional assemblies including an active and an inactive conformation of the vesicular ATPase complex as well as non-conventional arrangements of the luminal loops of SV2A, Synaptophysin and structurally related proteins. Based on this network, we specifically target Synaptobrevin-2, which connects with many proteins, in different approaches. Our results allow distinction of interactions caused by 'crowding' in the vesicle membrane from stable interaction modules.
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Affiliation(s)
- Sabine Wittig
- Interdisciplinary Research Centre HALOmem, Charles Tanford Protein Centre, Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Marcelo Ganzella
- Department for Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Marie Barth
- Interdisciplinary Research Centre HALOmem, Charles Tanford Protein Centre, Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Susann Kostmann
- Interdisciplinary Research Centre HALOmem, Charles Tanford Protein Centre, Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Dietmar Riedel
- Department for Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Ángel Pérez-Lara
- Department for Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Department of Physical Chemistry, Faculty of Pharmacy, University of Granada, Granada, Spain
| | - Reinhard Jahn
- Department for Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Carla Schmidt
- Interdisciplinary Research Centre HALOmem, Charles Tanford Protein Centre, Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle, Germany.
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15
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Radhakrishnan A, Li X, Grushin K, Krishnakumar SS, Liu J, Rothman JE. Symmetrical arrangement of proteins under release-ready vesicles in presynaptic terminals. Proc Natl Acad Sci U S A 2021; 118:e2024029118. [PMID: 33468631 PMCID: PMC7865176 DOI: 10.1073/pnas.2024029118] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Controlled release of neurotransmitters stored in synaptic vesicles (SVs) is a fundamental process that is central to all information processing in the brain. This relies on tight coupling of the SV fusion to action potential-evoked presynaptic Ca2+ influx. This Ca2+-evoked release occurs from a readily releasable pool (RRP) of SVs docked to the plasma membrane (PM). The protein components involved in initial SV docking/tethering and the subsequent priming reactions which make the SV release ready are known. Yet, the supramolecular architecture and sequence of molecular events underlying SV release are unclear. Here, we use cryoelectron tomography analysis in cultured hippocampal neurons to delineate the arrangement of the exocytosis machinery under docked SVs. Under native conditions, we find that vesicles are initially "tethered" to the PM by a variable number of protein densities (∼10 to 20 nm long) with no discernible organization. In contrast, we observe exactly six protein masses, each likely consisting of a single SNAREpin with its bound Synaptotagmins and Complexin, arranged symmetrically connecting the "primed" vesicles to the PM. Our data indicate that the fusion machinery is likely organized into a highly cooperative framework during the priming process which enables rapid SV fusion and neurotransmitter release following Ca2+ influx.
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Affiliation(s)
| | - Xia Li
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06520
- Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT 06520
| | - Kirill Grushin
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520
| | - Shyam S Krishnakumar
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520;
| | - Jun Liu
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06520;
- Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT 06520
| | - James E Rothman
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520;
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16
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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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17
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Enhanced oligomerization of full-length RAGE by synergy of the interaction of its domains. Sci Rep 2019; 9:20332. [PMID: 31889156 PMCID: PMC6937306 DOI: 10.1038/s41598-019-56993-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 12/11/2019] [Indexed: 01/10/2023] Open
Abstract
The pattern recognition receptor RAGE (receptor for advanced glycation end-products) transmits proinflammatory signals in several inflammation-related pathological states, including vascular diseases, cancer, neurodegeneration and diabetes. Its oligomerization is believed to be important in signal transduction, but RAGE oligomeric structures and stoichiometries remain unclear. Different oligomerization modes have been proposed in studies involving different truncated versions of the extracellular parts of RAGE. Here, we provide basic characterization of the oligomerization patterns of full-length RAGE (including the transmembrane (TM) and cytosolic regions) and compare the results with oligomerization modes of its four truncated fragments. For this purpose, we used native mass spectrometry, analytical ultracentrifugation, and size-exclusion chromatography coupled with multi-angle light scattering. Our results confirm known oligomerization tendencies of separate domains and highlight the enhanced oligomerization properties of full-length RAGE. Mutational analyses within the GxxxG motif of the TM region show sensitivity of oligomeric distributions to the TM sequence. Using hydrogen–deuterium exchange, we mapped regions involved in TM-dependent RAGE oligomerization. Our data provide experimental evidence for the major role of the C2 and TM domains in oligomerization, underscoring synergy among different oligomerization contact regions along the RAGE sequence. These results also explain the variability of obtained oligomerization modes in RAGE fragments.
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18
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Lara-Lemus R. On The Role of Myelin and Lymphocyte Protein (MAL) In Cancer: A Puzzle With Two Faces. J Cancer 2019; 10:2312-2318. [PMID: 31258734 PMCID: PMC6584422 DOI: 10.7150/jca.30376] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 02/07/2019] [Indexed: 12/25/2022] Open
Abstract
Myelin and lymphocyte protein (MAL) is an integral membrane protein constituent of lipid rafts, and it is implicated in apical transport of proteins in polarized epithelial cells. However, beyond the involvement of MAL in apical sorting and as its function as a raft stabilizer, it is still not totally clear how MAL participates in cell proliferating processes. More controversial and interesting is the fact that MAL has been implicated in carcinogenesis in two opposite ways. First, this protein is overexpressed in ovarian cancer and some kinds of lymphomas where it seems to favor cancer progression. Conversely, it has been reported that downregulation of the MAL gene by promoter hypermethylation is a hallmark of several adenocarcinomas. So far, there is not enough experimental evidence to help us understand this phenomenon, and no MAL mutations or MAL isoforms have been associated with these opposite functions. This review provides an updated summary of the structure and functions of MAL, and we will discuss the possible mechanisms underlying its roles as a tumor suppressor and a tumor progression factor.
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Affiliation(s)
- Roberto Lara-Lemus
- Department of Research in Biochemistry, Instituto Nacional de Enfermedades Respiratorias “Ismael Cosío Villegas”. Mexico City, 14080. Mexico
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19
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Calahorro F, Izquierdo PG. The presynaptic machinery at the synapse of C. elegans. INVERTEBRATE NEUROSCIENCE : IN 2018; 18:4. [PMID: 29532181 PMCID: PMC5851683 DOI: 10.1007/s10158-018-0207-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 02/22/2018] [Indexed: 11/17/2022]
Abstract
Synapses are specialized contact sites that mediate information flow between neurons and their targets. Important physical interactions across the synapse are mediated by synaptic adhesion molecules. These adhesions regulate formation of synapses during development and play a role during mature synaptic function. Importantly, genes regulating synaptogenesis and axon regeneration are conserved across the animal phyla. Genetic screens in the nematode Caenorhabditis elegans have identified a number of molecules required for synapse patterning and assembly. C. elegans is able to survive even with its neuronal function severely compromised. This is in comparison with Drosophila and mice where increased complexity makes them less tolerant to impaired function. Although this fact may reflect differences in the function of the homologous proteins in the synapses between these organisms, the most likely interpretation is that many of these components are equally important, but not absolutely essential, for synaptic transmission to support the relatively undemanding life style of laboratory maintained C. elegans. Here, we review research on the major group of synaptic proteins, involved in the presynaptic machinery in C. elegans, showing a strong conservation between higher organisms and highlight how C. elegans can be used as an informative tool for dissecting synaptic components, based on a simple nervous system organization.
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Affiliation(s)
- Fernando Calahorro
- Biological Sciences, University of Southampton, Life Sciences Building 85, Southampton, SO17 1BJ, UK.
| | - Patricia G Izquierdo
- Biological Sciences, University of Southampton, Life Sciences Building 85, Southampton, SO17 1BJ, UK
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20
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Mori Y, Takamori S. Molecular Signatures Underlying Synaptic Vesicle Cargo Retrieval. Front Cell Neurosci 2018; 11:422. [PMID: 29379416 PMCID: PMC5770824 DOI: 10.3389/fncel.2017.00422] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Accepted: 12/15/2017] [Indexed: 12/31/2022] Open
Abstract
Efficient retrieval of the synaptic vesicle (SV) membrane from the presynaptic plasma membrane, a process called endocytosis, is crucial for the fidelity of neurotransmission, particularly during sustained neural activity. Although multiple modes of endocytosis have been identified, it is clear that the efficient retrieval of the major SV cargos into newly formed SVs during any of these modes is fundamental for synaptic transmission. It is currently believed that SVs are eventually reformed via a clathrin-dependent pathway. Various adaptor proteins recognize SV cargos and link them to clathrin, ensuring the efficient retrieval of the cargos into newly formed SVs. Here, we summarize our current knowledge of the molecular signatures within individual SV cargos that underlie efficient retrieval into SV membranes, as well as discuss possible contributions of the mechanisms under physiological conditions.
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Affiliation(s)
- Yasunori Mori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto, Japan
| | - Shigeo Takamori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto, Japan
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21
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Sherif RN. Effect of cerebrolysin on the cerebellum of diabetic rats: An imunohistochemical study. Tissue Cell 2017; 49:726-733. [DOI: 10.1016/j.tice.2017.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Revised: 10/13/2017] [Accepted: 10/23/2017] [Indexed: 02/06/2023]
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22
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Chang CW, Chiang CW, Jackson MB. Fusion pores and their control of neurotransmitter and hormone release. J Gen Physiol 2017; 149:301-322. [PMID: 28167663 PMCID: PMC5339513 DOI: 10.1085/jgp.201611724] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Revised: 01/06/2017] [Accepted: 01/19/2017] [Indexed: 11/20/2022] Open
Abstract
Chang et al. review fusion pore structure and dynamics and discuss the implications for hormone and neurotransmitter release Ca2+-triggered exocytosis functions broadly in the secretion of chemical signals, enabling neurons to release neurotransmitters and endocrine cells to release hormones. The biological demands on this process can vary enormously. Although synapses often release neurotransmitter in a small fraction of a millisecond, hormone release can be orders of magnitude slower. Vesicles usually contain multiple signaling molecules that can be released selectively and conditionally. Cells are able to control the speed, concentration profile, and content selectivity of release by tuning and tailoring exocytosis to meet different biological demands. Much of this regulation depends on the fusion pore—the aqueous pathway by which molecules leave a vesicle and move out into the surrounding extracellular space. Studies of fusion pores have illuminated how cells regulate secretion. Furthermore, the formation and growth of fusion pores serve as a readout for the progress of exocytosis, thus revealing key kinetic stages that provide clues about the underlying mechanisms. Herein, we review the structure, composition, and dynamics of fusion pores and discuss the implications for molecular mechanisms as well as for the cellular regulation of neurotransmitter and hormone release.
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Affiliation(s)
- Che-Wei Chang
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705
| | - Chung-Wei Chiang
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705
| | - Meyer B Jackson
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705
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23
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Hami J, Vafaei-Nezhad S, Sadeghi A, Ghaemi K, Taheri MMH, Fereidouni M, Ivar G, Hosseini M. Synaptogenesis in the Cerebellum of Offspring Born to Diabetic Mothers. J Pediatr Neurosci 2017; 12:215-221. [PMID: 29204194 PMCID: PMC5696656 DOI: 10.4103/jpn.jpn_144_16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
There is increasing evidence that maternal diabetes mellitus during the pregnancy is associated with a higher risk of neurodevelopmental and neurofunctional anomalies including motor dysfunctions, learning deficits, and behavioral problems in offspring. The cerebellum is a part of the brain that has long been recognized as a center of movement balance and motor coordination. Moreover, recent studies in humans and animals have also implicated the cerebellum in cognitive processing, sensory discrimination, attention, and learning and memory. Synaptogenesis is one of the most crucial events during the development of the central nervous system. Synaptophysin (SYP) is an integral membrane protein of synaptic vesicles and is considered to be a marker for synaptic density and synaptogenesis. Here, we review the manuscripts focusing on the negative impacts of maternal diabetes in pregnancy on the expression or localization of SYP in the developing cerebellar cortex. We believe that the alteration in synaptogenesis or synapse density may be part of the cascade of events through which diabetes in pregnant women affects the newborn's cerebellum.
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Affiliation(s)
- Javad Hami
- Cellular and Molecular Research Center, Birjand University of Medical Sciences, Birjand, Iran.,Department of Anatomy, School of Medicine, Birjand University of Medical Sciences, Birjand, Iran
| | - Saeed Vafaei-Nezhad
- Cellular and Molecular Research Center, Birjand University of Medical Sciences, Birjand, Iran.,Department of Anatomy, School of Medicine, Birjand University of Medical Sciences, Birjand, Iran
| | - Akram Sadeghi
- Cellular and Molecular Research Center, Birjand University of Medical Sciences, Birjand, Iran.,Department of Anatomy, School of Medicine, Birjand University of Medical Sciences, Birjand, Iran
| | - Kazem Ghaemi
- Department of Neurosurgery, School of Medicine, Birjand University of Medical Sciences, Birjand, Iran
| | | | - Mohammad Fereidouni
- Cellular and Molecular Research Center, Birjand University of Medical Sciences, Birjand, Iran.,Department of Immunology, School of Medicine, Birjand University of Medical Sciences, Birjand, Iran
| | - Ghasem Ivar
- Department of Anatomy, School of Medicine, Birjand University of Medical Sciences, Birjand, Iran
| | - Mehran Hosseini
- Department of Public Health, Research Centre of Experimental Medicine, Birjand University of Medical Sciences, Birjand, Iran
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24
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Characterization of the Tetraspan Junctional Complex (4JC) superfamily. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:402-414. [PMID: 27916633 DOI: 10.1016/j.bbamem.2016.11.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 11/22/2016] [Accepted: 11/29/2016] [Indexed: 12/31/2022]
Abstract
Connexins or innexins form gap junctions, while claudins and occludins form tight junctions. In this study, statistical data, derived using novel software, indicate that these four junctional protein families and eleven other families of channel and channel auxiliary proteins are related by common descent and comprise the Tetraspan (4 TMS) Junctional Complex (4JC) Superfamily. These proteins all share similar 4 transmembrane α-helical (TMS) topologies. Evidence is presented that they arose via an intragenic duplication event, whereby a 2 TMS-encoding genetic element duplicated tandemly to give 4 TMS proteins. In cases where high resolution structural data were available, the conclusion of homology was supported by conducting structural comparisons. Phylogenetic trees reveal the probable relationships of these 15 families to each other. Long homologues containing fusions to other recognizable domains as well as internally duplicated or fused domains are reported. Large "fusion" proteins containing 4JC domains proved to fall predominantly into family-specific patterns as follows: (1) the 4JC domain was N-terminal; (2) the 4JC domain was C-terminal; (3) the 4JC domain was duplicated or occasionally triplicated and (4) mixed fusion types were present. Our observations provide insight into the evolutionary origins and subfunctions of these proteins as well as guides concerning their structural and functional relationships.
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Hami J, Vafaei-Nezhad S, Ivar G, Sadeghi A, Ghaemi K, Mostafavizadeh M, Hosseini M. Altered expression and localization of synaptophysin in developing cerebellar cortex of neonatal rats due to maternal diabetes mellitus. Metab Brain Dis 2016; 31:1369-1380. [PMID: 27389246 DOI: 10.1007/s11011-016-9864-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Accepted: 06/28/2016] [Indexed: 12/30/2022]
Abstract
There is sufficient evidence that diabetes during pregnancy is associated with a higher risk of neurodevelopmental anomalies including learning deficits, behavioral problems and motor dysfunctions in the offspring. Synaptophysin (SYP) is an integral membrane protein of synaptic vesicles and is considered as a marker for synaptogenesis and synaptic density. This study aimed to examine the effects of maternal diabetes in pregnancy on the expression and localization of SYP in the developing rat cerebellum. Wistar female rats were maintained diabetic from a week before pregnancy through parturition and male offspring was euthanized at postnatal day (P) 0, 7, and 14. The results revealed a significant down-regulation in the mRNA expression of SYP in the offspring born to diabetic animals at both P7 and P14 (P < 0.05 each). One week after birth, there was a significant reduction in the localization of SYP expression in the external granular (EGL) and in the molecular (ML) layers of neonates born to diabetic animals (P < 0.05 each). We also found a marked decrease in the expression of SYP in all of the cerebellar cortical layers of STZ-D group pups at P14 (P < 0.05 each). Moreover, our results revealed no significant changes in either expression or localization of SYP in insulin-treated group pups when compared with the controls (P ≥ 0.05 each). The present study demonstrated that maternal diabetes has adverse effects on the synaptogenesis in the offspring's cerebellum. Furthermore, the rigid maternal blood glucose control in the most cases normalized these negative impacts.
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Affiliation(s)
- Javad Hami
- Department of Anatomical Sciences, School of Medicine, Birjand University of Medical Sciences, Ghaffari St, Birjand, Iran
| | - Saeed Vafaei-Nezhad
- Department of Anatomical Sciences, School of Medicine, Birjand University of Medical Sciences, Ghaffari St, Birjand, Iran.
| | - Ghasem Ivar
- Department of Anatomical Sciences, School of Medicine, Birjand University of Medical Sciences, Ghaffari St, Birjand, Iran
| | - Akram Sadeghi
- Department of Anatomy and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Kazem Ghaemi
- Department of Neurosurgery, School of Medicine, Birjand University of Medical Sciences, Birjand, Iran
| | | | - Mehran Hosseini
- Department of Public Health, Deputy of Research and Technology, Research Centre of Experimental Medicine, Birjand University of Medical Sciences, Birjand, Iran
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Attwood MM, Krishnan A, Pivotti V, Yazdi S, Almén MS, Schiöth HB. Topology based identification and comprehensive classification of four-transmembrane helix containing proteins (4TMs) in the human genome. BMC Genomics 2016; 17:268. [PMID: 27030248 PMCID: PMC4815072 DOI: 10.1186/s12864-016-2592-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 03/16/2016] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Membrane proteins are key components in a large spectrum of diverse functions and thus account for the major proportion of the drug-targeted portion of the genome. From a structural perspective, the α-helical transmembrane proteins can be categorized into major groups based on the number of transmembrane helices and these groups are often associated with specific functions. When compared to the well-characterized seven-transmembrane containing proteins (7TM), other TM groups are less explored and in particular the 4TM group. In this study, we identify the complete 4TM complement from the latest release of the human genome and assess the 4TM structure group as a whole. We functionally characterize this dataset and evaluate the resulting groups and ubiquitous functions, and furthermore describe disease and drug target involvement. RESULTS We classified 373 proteins, which represents ~7 % of the human membrane proteome, and includes 69 more proteins than our previous estimate. We have characterized the 4TM dataset based on functional, structural, and/or evolutionary similarities. Proteins that are involved in transport activity constitute 37 % of the dataset, 23 % are receptor-related, and 13 % have enzymatic functions. Intriguingly, proteins involved in transport are more than double the 15 % of transporters in the entire human membrane proteome, which might suggest that the 4TM topological architecture is more favored for transporting molecules over other functions. Moreover, we found an interesting exception to the ubiquitous intracellular N- and C-termini localization that is found throughout the entire membrane proteome and 4TM dataset in the neurotransmitter gated ion channel families. Overall, we estimate that 58 % of the dataset has a known association to disease conditions with 19 % of the genes possibly involved in different types of cancer. CONCLUSIONS We provide here the most robust and updated classification of the 4TM complement of the human genome as a platform to further understand the characteristics of 4TM functions and to explore pharmacological opportunities.
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Affiliation(s)
- Misty M. Attwood
- />Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
| | - Arunkumar Krishnan
- />Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
| | - Valentina Pivotti
- />Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
| | - Samira Yazdi
- />Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
| | - Markus Sällman Almén
- />Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
| | - Helgi B. Schiöth
- />Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
- />Institutionen för neurovetenskap, BMC, Box 593, 751 24 Uppsala, Sweden
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Accurate Determination of Conformational Transitions in Oligomeric Membrane Proteins. Sci Rep 2016; 6:23063. [PMID: 26975211 PMCID: PMC4791661 DOI: 10.1038/srep23063] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 02/25/2016] [Indexed: 12/27/2022] Open
Abstract
The structural dynamics governing collective motions in oligomeric membrane proteins play key roles in vital biomolecular processes at cellular membranes. In this study, we present a structural refinement approach that combines solid-state NMR experiments and molecular simulations to accurately describe concerted conformational transitions identifying the overall structural, dynamical, and topological states of oligomeric membrane proteins. The accuracy of the structural ensembles generated with this method is shown to reach the statistical error limit, and is further demonstrated by correctly reproducing orthogonal NMR data. We demonstrate the accuracy of this approach by characterising the pentameric state of phospholamban, a key player in the regulation of calcium uptake in the sarcoplasmic reticulum, and by probing its dynamical activation upon phosphorylation. Our results underline the importance of using an ensemble approach to characterise the conformational transitions that are often responsible for the biological function of oligomeric membrane protein states.
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The impacts of diabetes in pregnancy on hippocampal synaptogenesis in rat neonates. Neuroscience 2016; 318:122-33. [DOI: 10.1016/j.neuroscience.2016.01.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 12/28/2015] [Accepted: 01/11/2016] [Indexed: 11/21/2022]
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Gordon SL, Harper CB, Smillie KJ, Cousin MA. A Fine Balance of Synaptophysin Levels Underlies Efficient Retrieval of Synaptobrevin II to Synaptic Vesicles. PLoS One 2016; 11:e0149457. [PMID: 26871701 PMCID: PMC4752265 DOI: 10.1371/journal.pone.0149457] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 01/31/2016] [Indexed: 12/25/2022] Open
Abstract
Synaptobrevin II (sybII) is a vesicular soluble NSF attachment protein receptor (SNARE) protein that is essential for neurotransmitter release, and thus its correct trafficking to synaptic vesicles (SVs) is critical to render them fusion competent. The SV protein synaptophysin binds to sybII and facilitates its retrieval to SVs during endocytosis. Synaptophysin and sybII are the two most abundant proteins on SVs, being present in a 1:2 ratio. Synaptophysin and sybII are proposed to form a large multimeric complex, and the copy number of the proteins in this complex is also in a 1:2 ratio. We investigated the importance of this ratio between these proteins for the localisation and trafficking of sybII in central neurons. SybII was overexpressed in mouse hippocampal neurons at either 1.6 or 2.15–2.35-fold over endogenous protein levels, in the absence or presence of varying levels of synaptophysin. In the absence of exogenous synaptophysin, exogenous sybII was dispersed along the axon, trapped on the plasma membrane and retrieved slowly during endocytosis. Co-expression of exogenous synaptophysin rescued all of these defects. Importantly, the expression of synaptophysin at nerve terminals in a 1:2 ratio with sybII was sufficient to fully rescue normal sybII trafficking. These results demonstrate that the balance between synaptophysin and sybII levels is critical for the correct targeting of sybII to SVs and suggests that small alterations in synaptophysin levels might affect the localisation of sybII and subsequent presynaptic performance.
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Affiliation(s)
- Sarah L. Gordon
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, 3052, Victoria, Australia
- * E-mail: (SG); (MC)
| | - Callista B. Harper
- Centre for Integrative Physiology, George Square, University of Edinburgh, EH8 9XD Edinburgh, United Kingdom
| | - Karen J. Smillie
- Centre for Integrative Physiology, George Square, University of Edinburgh, EH8 9XD Edinburgh, United Kingdom
| | - Michael A. Cousin
- Centre for Integrative Physiology, George Square, University of Edinburgh, EH8 9XD Edinburgh, United Kingdom
- * E-mail: (SG); (MC)
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Gordon SL, Cousin MA. The iTRAPs: Guardians of Synaptic Vesicle Cargo Retrieval During Endocytosis. Front Synaptic Neurosci 2016; 8:1. [PMID: 26903854 PMCID: PMC4746236 DOI: 10.3389/fnsyn.2016.00001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 01/25/2016] [Indexed: 11/30/2022] Open
Abstract
The reformation of synaptic vesicles (SVs) during endocytosis is essential for the maintenance of neurotransmission in central nerve terminals. Newly formed SVs must be generated with the correct protein cargo in the correct stoichiometry to be functional for exocytosis. Classical clathrin adaptor protein complexes play a key role in sorting and clustering synaptic vesicle cargo in this regard. However it is becoming increasingly apparent that additional “fail-safe” mechanisms exist to ensure the accurate retrieval of essential cargo molecules. For example, the monomeric adaptor proteins AP180/CALM and stonin-2 are required for the efficient retrieval of synaptobrevin II (sybII) and synaptotagmin-1 respectively. Furthermore, recent studies have revealed that sybII and synaptotagmin-1 interact with other SV cargoes to ensure a high fidelity of retrieval. These cargoes are synaptophysin (for sybII) and SV2A (for synaptotagmin-1). In this review, we summarize current knowledge regarding the retrieval mechanisms for both sybII and synaptotagmin-1 during endocytosis. We also define and set criteria for a new functional group of SV molecules that facilitate the retrieval of their interaction partners. We have termed these molecules intrinsic trafficking partners (iTRAPs) and we discuss how the function of this group impacts on presynaptic performance in both health and disease.
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Affiliation(s)
- Sarah L Gordon
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne Parkville, VIC, Australia
| | - Michael A Cousin
- Centre for Integrative Physiology, University of Edinburgh Edinburgh, UK
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Abstract
Symmetry is a common feature among natural systems, including protein structures. A strong propensity toward symmetric architectures has long been recognized for water-soluble proteins, and this propensity has been rationalized from an evolutionary standpoint. Proteins residing in cellular membranes, however, have traditionally been less amenable to structural studies, and thus the prevalence and significance of symmetry in this important class of molecules is not as well understood. In the past two decades, researchers have made great strides in this area, and these advances have provided exciting insights into the range of architectures adopted by membrane proteins. These structural studies have revealed a similarly strong bias toward symmetric arrangements, which were often unexpected and which occurred despite the restrictions imposed by the membrane environment on the possible symmetry groups. Moreover, membrane proteins disproportionately contain internal structural repeats resulting from duplication and fusion of smaller segments. This article discusses the types and origins of symmetry in membrane proteins and the implications of symmetry for protein function.
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Affiliation(s)
- Lucy R Forrest
- Computational Structural Biology Group, Porter Neuroscience Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20852;
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Morphometric analysis of the age-related changes of synaptophysin immunoreactivity in the human parahippocampal region. J ANAT SOC INDIA 2015. [DOI: 10.1016/j.jasi.2015.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Abstract
In the CNS (central nervous system), nerve cells communicate by transmitting signals from one to the next across chemical synapses. Electrical signals trigger controlled secretion of neurotransmitter by exocytosis of SV (synaptic vesicles) at the presynaptic site. Neurotransmitters diffuse across the synaptic cleft, activate receptor channels in the receiving neuron at the postsynaptic site, and thereby elicit a new electrical signal. Repetitive stimulation should result in fast depletion of fusion-competent SVs, given their limited number in the presynaptic bouton. Therefore, to support repeated rounds of release, a fast trafficking cycle is required that couples exocytosis and compensatory endocytosis. During this exo-endocytic cycle, a defined stoichiometry of SV proteins has to be preserved, that is, membrane proteins have to be sorted precisely. However, how this sorting is accomplished on a molecular level is poorly understood. In the present chapter we review recent findings regarding the molecular composition of SVs and the mechanisms that sort SV proteins during compensatory endocytosis. We identify self-assembly of SV components and individual cargo recognition by sorting adaptors as major mechanisms for maintenance of the SV protein complement.
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Architecture of the Synaptophysin/Synaptobrevin Complex: Structural Evidence for an Entropic Clustering Function at the Synapse. Sci Rep 2015; 5:13659. [PMID: 26333660 PMCID: PMC4558601 DOI: 10.1038/srep13659] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 07/27/2015] [Indexed: 01/14/2023] Open
Abstract
We have purified the mammalian synaptophysin/synaptobrevin (SYP/VAMP2) complex to homogeneity in the presence of cholesterol and determined the 3D EM structure by single particle reconstruction. The structure reveals that SYP and VAMP2 assemble into a hexameric ring wherein 6 SYP molecules bind 6 VAMP2 dimers. Using the EM map as a constraint, a three dimensional atomic model was built and refined using known atomic structures and homology modeling. The overall architecture of the model suggests a simple mechanism to ensure cooperativity of synaptic vesicle fusion by organizing multiple VAMP2 molecules such that they are directionally oriented towards the target membrane. This is the first three dimensional architectural data for the SYP/VAMP2 complex and provides a structural foundation for understanding the role of this complex in synaptic transmission.
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Andersen Ø, Johnsen H, De Rosa MC, Præbel K, Stjelja S, Kirubakaran TG, Pirolli D, Jentoft S, Fevolden SE. Evolutionary history and adaptive significance of the polymorphic Pan I in migratory and stationary populations of Atlantic cod (Gadus morhua). Mar Genomics 2015; 22:45-54. [DOI: 10.1016/j.margen.2015.03.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/19/2015] [Accepted: 03/19/2015] [Indexed: 11/27/2022]
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36
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Sulforaphane rescues memory dysfunction and synaptic and mitochondrial alterations induced by brain iron accumulation. Neuroscience 2015; 301:542-52. [DOI: 10.1016/j.neuroscience.2015.06.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 06/13/2015] [Accepted: 06/16/2015] [Indexed: 12/14/2022]
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Dubois L, Stridsberg M, Kharaziha P, Chioureas D, Meersman N, Panaretakis T, Ronquist KG. Malignant cell-derived extracellular vesicles express different chromogranin epitopes compared to prostasomes. Prostate 2015; 75:1063-73. [PMID: 25783430 DOI: 10.1002/pros.22990] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 02/05/2015] [Indexed: 01/09/2023]
Abstract
BACKGROUND Prostasomes are nanosized extracellular vesicles exocytosed by prostate epithelial cells. They have been assigned many roles propitious to sperm in favor of fertilization. Prostatic cancer cells can also produce and secrete extracellular vesicles. METHODS We assessed using ELISA, the surface expression of chromogranin proproteins on prostasomes and malignant extracellular vesicles of four different prostate cancer cell-lines, two hormone sensitive and two hormone refractory. We used a panel of chromogranin A and chromogranin B antibodies against peptides in-between hypothetical cleavage sites along the proproteins. RESULTS A diverging pattern of chromogranin peptides was apparent when comparing prostasomes and malignant extracellular vesicles indicating a phenotypical change. We also compared western blot patterns (prostasomes and malignant extracellular vesicles) for selected antibodies that displayed high absorbances in the ELISA. Western blot analyses revealed various cleavage patterns of those proproteins that were analyzed in prostasomes and extracellular vesicles. CONCLUSION Chromogranins are constituents of not only prostasomes but also of malignant prostate cell-derived extracellular vesicles with different amino acid sequences exposed at the membrane surface giving rise to a mosaic pattern. These findings may be of relevance for designing new assays for detection or even possible treatment of prostate cancers.
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Affiliation(s)
- Louise Dubois
- Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Mats Stridsberg
- Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Pedram Kharaziha
- Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Dimitris Chioureas
- Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | | | | | - K Göran Ronquist
- Department of Medical Sciences, Uppsala University, Uppsala, Sweden
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38
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Wang ZY, Shi M, Li Y. Importin-β1 plays a key role in the nucleocytoplasmic transportation process of MARVELD1. Mol Biol 2015. [DOI: 10.1134/s002689331503019x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Li Q, Zhu XL, Jin AP, Liu XY, Zhao YX. Inhibition of synaptophysin ubiquitination may improve the intelligent drop due to high glucose and hypoxia. Int J Clin Exp Med 2014; 7:5021-5030. [PMID: 25664001 PMCID: PMC4307448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 12/08/2014] [Indexed: 06/04/2023]
Abstract
Synaptophysin (SYP) is a synaptic vesicle membrane protein and involved in the release of neurotransmitters, synaptic plasticity, and formation and recycling of synaptic vesicles. SYP may serve as a specific marker of synaptic proteins. Our results showed high glucose and hypoxia could significantly impair the intelligence and the SYP level was positively related to the degree of intelligence in animals. Ubiquitination may influence the SYP expression. In our study, an ubiquitination inhibitor (MG-132) was injected intraperitoneally. Results showed this could increase SYP expression in the brain to improve the intelligent drop due to high glucose and hypoxia in animals. SYP ubiquitination is closely associated with E3 ubiquitin ligase, a mammalian homologue of seven in absentia. In our study, lentivirus expressing siah shRNA was injected into the cerebral ventricle to down-regulate siah expression, and results showed the SYP expression in the brain increased markedly. In addition, we also found that VitK3 could increase the SYP expression in the brain to improve the intelligent drop due to high glucose and hypoxia.
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Affiliation(s)
- Qiang Li
- Department of Neurology, Tenth People's Hospital, Tongji University 301# Middle Yanchang Road, Shanghai 200072, China
| | - Xiao-Long Zhu
- Department of Neurology, Tenth People's Hospital, Tongji University 301# Middle Yanchang Road, Shanghai 200072, China
| | - Ai-Ping Jin
- Department of Neurology, Tenth People's Hospital, Tongji University 301# Middle Yanchang Road, Shanghai 200072, China
| | - Xue-Yuan Liu
- Department of Neurology, Tenth People's Hospital, Tongji University 301# Middle Yanchang Road, Shanghai 200072, China
| | - Yan-Xin Zhao
- Department of Neurology, Tenth People's Hospital, Tongji University 301# Middle Yanchang Road, Shanghai 200072, China
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Gordon SL, Cousin MA. The Sybtraps: control of synaptobrevin traffic by synaptophysin, α-synuclein and AP-180. Traffic 2013; 15:245-54. [PMID: 24279465 PMCID: PMC3992847 DOI: 10.1111/tra.12140] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 11/22/2013] [Accepted: 11/26/2013] [Indexed: 01/18/2023]
Abstract
Synaptobrevin II (sybII) is a key fusogenic molecule on synaptic vesicles (SVs) therefore the active maintenance of both its conformation and location in sufficient numbers on this organelle is critical in both mediating and sustaining neurotransmitter release. Recently three proteins have been identified having key roles in the presentation, trafficking and retrieval of sybII during the fusion and endocytosis of SVs. The nerve terminal protein α-synuclein catalyses sybII entry into SNARE complexes, whereas the monomeric adaptor protein AP-180 is required for sybII retrieval during SV endocytosis. Overarching these events is the tetraspan SV protein synaptophysin, which is a major sybII interaction partner on the SV. This review will evaluate recent studies to propose working models for the control of sybII traffic by synaptophysin and other Sybtraps (sybII trafficking partners) and suggest how dysfunction in sybII traffic may contribute to human disease.
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Affiliation(s)
- Sarah L Gordon
- Membrane Biology Group, Centre for Integrative Physiology, George Square, University of Edinburgh, Scotland, EH8 9XD, UK
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X-linked intellectual disability-associated mutations in synaptophysin disrupt synaptobrevin II retrieval. J Neurosci 2013; 33:13695-700. [PMID: 23966691 DOI: 10.1523/jneurosci.0636-13.2013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Synaptophysin is an integral synaptic vesicle (SV) protein that accounts for ∼10% of total SV protein cargo. Deletion of synaptophysin results in the defective retrieval of synaptobrevin II (sybII) from the plasma membrane during endocytosis, coupled with a slowing in the speed of endocytosis. Synaptophysin has been implicated in X-linked intellectual disability, with a recent study identifying four separate synaptophysin gene mutations in families affected by the disorder. To determine how these mutations may affect synaptophysin function, we expressed them in cultured neurons derived from synaptophysin knock-out mice. Two distinct truncating mutants were mislocalized throughout the axon and phenocopied the arrest of sybII retrieval in synaptophysin knock-out cultures. The remaining two mutants displayed a nerve terminal localization but did not support efficient sybII retrieval. Interestingly, one mutant fully rescued SV endocytosis kinetics, suggesting that sybII retrieval and endocytosis speed are independent from each other. These studies suggest that the efficient retrieval of sybII by synaptophysin may be key to maintaining synaptic health and perturbation of this event may contribute to the pathogenesis underlying neurodevelopmental disorders such as X-linked intellectual disability.
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Lin JY, Sann SB, Zhou K, Nabavi S, Proulx CD, Malinow R, Jin Y, Tsien RY. Optogenetic inhibition of synaptic release with chromophore-assisted light inactivation (CALI). Neuron 2013; 79:241-53. [PMID: 23889931 DOI: 10.1016/j.neuron.2013.05.022] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/15/2013] [Indexed: 12/18/2022]
Abstract
Optogenetic techniques provide effective ways of manipulating the functions of selected neurons with light. In the current study, we engineered an optogenetic technique that directly inhibits neurotransmitter release. We used a genetically encoded singlet oxygen generator, miniSOG, to conduct chromophore assisted light inactivation (CALI) of synaptic proteins. Fusions of miniSOG to VAMP2 and synaptophysin enabled disruption of presynaptic vesicular release upon illumination with blue light. In cultured neurons and hippocampal organotypic slices, synaptic release was reduced up to 100%. Such inhibition lasted >1 hr and had minimal effects on membrane electrical properties. When miniSOG-VAMP2 was expressed panneuronally in Caenorhabditis elegans, movement of the worms was reduced after illumination, and paralysis was often observed. The movement of the worms recovered overnight. We name this technique Inhibition of Synapses with CALI (InSynC). InSynC is a powerful way to silence genetically specified synapses with light in a spatially and temporally precise manner.
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Affiliation(s)
- John Y Lin
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093-0647, USA.
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Abstract
Sustained neuronal communication relies on the coordinated activity of multiple proteins that regulate synaptic vesicle biogenesis and cycling within the presynaptic terminal. Synaptogyrin and synaptophysin are conserved MARVEL domain-containing transmembrane proteins that are among the most abundant synaptic vesicle constituents, although their role in the synaptic vesicle cycle has remained elusive. To further investigate the function of these proteins, we generated and characterized a synaptogyrin (gyr)-null mutant in Drosophila, whose genome encodes a single synaptogyrin isoform and lacks a synaptophysin homolog. We demonstrate that Drosophila synaptogyrin plays a modulatory role in synaptic vesicle biogenesis at larval neuromuscular junctions. Drosophila lacking synaptogyrin are viable and fertile and have no overt deficits in motor function. However, ultrastructural analysis of gyr larvae revealed increased synaptic vesicle diameter and enhanced variability in the size of synaptic vesicles. In addition, the resolution of endocytic cisternae into synaptic vesicles in response to strong stimulation is defective in gyr mutants. Electrophysiological analysis demonstrated an increase in quantal size and a concomitant decrease in quantal content, suggesting functional consequences for transmission caused by the loss of synaptogyrin. Furthermore, high-frequency stimulation resulted in increased facilitation and a delay in recovery from synaptic depression, indicating that synaptic vesicle exo-endocytosis is abnormally regulated during intense stimulation conditions. These results suggest that synaptogyrin modulates the synaptic vesicle exo-endocytic cycle and is required for the proper biogenesis of synaptic vesicles at nerve terminals.
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Mallozzi C, D'Amore C, Camerini S, Macchia G, Crescenzi M, Petrucci TC, Di Stasi AMM. Phosphorylation and nitration of tyrosine residues affect functional properties of Synaptophysin and Dynamin I, two proteins involved in exo-endocytosis of synaptic vesicles. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:110-21. [DOI: 10.1016/j.bbamcr.2012.10.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 10/08/2012] [Accepted: 10/21/2012] [Indexed: 12/14/2022]
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Russell CL, Semerdjieva S, Empson RM, Austen BM, Beesley PW, Alifragis P. Amyloid-β acts as a regulator of neurotransmitter release disrupting the interaction between synaptophysin and VAMP2. PLoS One 2012; 7:e43201. [PMID: 22905234 PMCID: PMC3419646 DOI: 10.1371/journal.pone.0043201] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 07/18/2012] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND It is becoming increasingly evident that deficits in the cortex and hippocampus at early stages of dementia in Alzheimer's disease (AD) are associated with synaptic damage caused by oligomers of the toxic amyloid-β peptide (Aβ42). However, the underlying molecular and cellular mechanisms behind these deficits are not fully understood. Here we provide evidence of a mechanism by which Aβ42 affects synaptic transmission regulating neurotransmitter release. METHODOLOGY/FINDINGS We first showed that application of 50 nM Aβ42 in cultured neurones is followed by its internalisation and translocation to synaptic contacts. Interestingly, our results demonstrate that with time, Aβ42 can be detected at the presynaptic terminals where it interacts with Synaptophysin. Furthermore, data from dissociated hippocampal neurons as well as biochemical data provide evidence that Aβ42 disrupts the complex formed between Synaptophysin and VAMP2 increasing the amount of primed vesicles and exocytosis. Finally, electrophysiology recordings in brain slices confirmed that Aβ42 affects baseline transmission. CONCLUSIONS/SIGNIFICANCE Our observations provide a necessary and timely insight into cellular mechanisms that underlie the initial pathological events that lead to synaptic dysfunction in Alzheimer's disease. Our results demonstrate a new mechanism by which Aβ42 affects synaptic activity.
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Affiliation(s)
- Claire L. Russell
- School of Biological Sciences, Royal Holloway University London, Surrey, United Kingdom
| | - Sophia Semerdjieva
- School of Biological Sciences, Royal Holloway University London, Surrey, United Kingdom
| | - Ruth M. Empson
- School of Biological Sciences, Royal Holloway University London, Surrey, United Kingdom
- Department of Physiology, University of Otago School of Medical Sciences, Dunedin, New Zealand
| | - Brian M. Austen
- Neurodegeneration Unit, Basic Medical Sciences, St George’s, University of London, Cranmer Terrace, London, United Kingdom
| | - Philip W. Beesley
- School of Biological Sciences, Royal Holloway University London, Surrey, United Kingdom
| | - Pavlos Alifragis
- School of Biological Sciences, Royal Holloway University London, Surrey, United Kingdom
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Pyeon HJ, Lee YI. Differential expression levels of synaptophysin through developmental stages in hippocampal region of mouse brain. Anat Cell Biol 2012; 45:97-102. [PMID: 22822464 PMCID: PMC3398181 DOI: 10.5115/acb.2012.45.2.97] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 06/13/2012] [Accepted: 06/25/2012] [Indexed: 01/09/2023] Open
Abstract
The formation of neural synapses according to the development and growth of neurite were usually studied with various markers. Of these markers, synaptophysin is a kind of synaptic protein located in the synaptic vesicle of neuron or neuroendocrine cell known to be distributed consistently in all neural synapses. The purpose of this study was to investigate differential expression levels and patterns of synaptic marker (synaptophysin) in the mouse hippocampal region according to the developmental stages of embryonic, neonatal, and adulthood respectively. In the embryonic and neonatal groups, synaptophysin immunofluorescence was almost defined to cornu ammonis subfields (CA1 and CA3) of hippocampus and subiculum proper in the hippocampal region. However in dentate gyrus, synaptophysin immunoreactivities were insignificant or absent in all developmental stages. In embryonic and neonatal hippocampus, the intensities of immunofluorescence were significantly different between molecular and oriens layers. Furthermore, those intensities were decreased considerably in both layers of neonatal group compared to embryonic. The results from this study will contribute to characterizing synaptogenic activities in the central nervous system through developmental stages.
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Affiliation(s)
- Hee-Jang Pyeon
- Department of NanoBio Medical Science, Dankook University College of Medicine, Cheonan, Korea
| | - Young-Il Lee
- Department of Anatomy, Dankook University College of Medicine, Cheonan, Korea
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47
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Kim YG, Lee YI. Differential Expressions of Synaptogenic Markers between Primary Cultured Cortical and Hippocampal Neurons. Exp Neurobiol 2012; 21:61-7. [PMID: 22792026 PMCID: PMC3381213 DOI: 10.5607/en.2012.21.2.61] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 02/13/2012] [Indexed: 11/19/2022] Open
Abstract
Primary dissociated neuronal cultures are widely used research tools to investigate of pathological mechanisms and to treat various central and peripheral nervous system problems including trauma and degenerative neuronal diseases. We introduced a protocol that utilizes hippocampal and cortical neurons from embryonic day 17 or 18 mice. We applied appropriate markers (GAP-43 and synaptophysin) to investigate whether neurite outgrowth and synaptogenesis can be distinguished at a particular period of time. GAP-43 was found along the neural processes in a typical granular pattern, and its expression increased proportionally as neurites lengthened during the early in vitro period. Unlike GAP-43, granular immunoreactive patterns of synaptophysin along the neurites were clearly found from day 2 in vitro with relatively high immunoreactive levels. Expression of synaptic markers from cortical neurons reached peak level earlier than that of hippocampal neurons, although neurite outgrowths of hippocampal neurons were faster than those of cortical neurons. The amount of peak synaptic markers expressed was also higher in cortical neurons than that in hippocampal neurons. These results strongly suggest the usefulness of primary cultured neurons from mice embryos for synaptic function and plasticity studies, because of their clear and typical patterns of morphology that establish synapses. Results from this study also suggest the proper amount of time in vitro according to neuronal types (cortical or hippocampal) when utilized in experiments related with synaptogenesis or synaptic activities.
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Affiliation(s)
- Yun-Gi Kim
- Department of NanoBio Medical Science, College of Medicine, Dankook University, Cheonan 330-714, Korea
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48
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Synaptogyrin-dependent modulation of synaptic neurotransmission in Caenorhabditis elegans. Neuroscience 2011; 190:75-88. [DOI: 10.1016/j.neuroscience.2011.05.069] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 05/20/2011] [Accepted: 05/28/2011] [Indexed: 01/31/2023]
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49
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Kwon SE, Chapman ER. Synaptophysin regulates the kinetics of synaptic vesicle endocytosis in central neurons. Neuron 2011; 70:847-54. [PMID: 21658579 DOI: 10.1016/j.neuron.2011.04.001] [Citation(s) in RCA: 320] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/01/2011] [Indexed: 01/27/2023]
Abstract
Despite being the most abundant synaptic vesicle membrane protein, the function of synaptophysin remains enigmatic. For example, synaptic transmission was reported to be completely normal in synaptophysin knockout mice; however, direct experiments to monitor the synaptic vesicle cycle have not been carried out. Here, using optical imaging and electrophysiological experiments, we demonstrate that synaptophysin is required for kinetically efficient endocytosis of synaptic vesicles in cultured hippocampal neurons. Truncation analysis revealed that distinct structural elements of synaptophysin differentially regulate vesicle retrieval during and after stimulation. Thus, synaptophysin regulates at least two phases of endocytosis to ensure vesicle availability during and after sustained neuronal activity.
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Affiliation(s)
- Sung E Kwon
- Howard Hughes Medical Institute and Department of Neuroscience, University of Wisconsin, Madison, WI 53706, USA
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50
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Blanchard J, Wanka L, Tung YC, Cárdenas-Aguayo MDC, LaFerla FM, Iqbal K, Grundke-Iqbal I. Pharmacologic reversal of neurogenic and neuroplastic abnormalities and cognitive impairments without affecting Aβ and tau pathologies in 3xTg-AD mice. Acta Neuropathol 2010; 120:605-21. [PMID: 20697724 DOI: 10.1007/s00401-010-0734-6] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 07/27/2010] [Accepted: 07/28/2010] [Indexed: 12/01/2022]
Abstract
In addition to the occurrence of numerous neurofibrillary tangles and Aβ plaques, neurogenesis and neuronal plasticity are markedly altered in Alzheimer disease (AD). Although the most popular therapeutic approach has been to inhibit neurodegeneration, another is to promote neurogenesis and neuronal plasticity by utilizing the regenerative capacity of the brain. Here we show that, in a transgenic mouse model of AD, 3xTg-AD mice, there was a marked deficit in neurogenesis and neuroplasticity, which occurred before the formation of any neurofibrillary tangles or Aβ plaques and was associated with cognitive impairment. Furthermore, peripheral administration of Peptide 6, an 11-mer, which makes an active region of ciliary neurotrophic factor (CNTF, amino acid residues 146-156), restored cognition by enhancing neurogenesis and neuronal plasticity in these mice. Although this treatment had no detectable effect on Aβ and tau pathologies in 9-month animals, it enhanced neurogenesis in dentate gyrus, reduced ectopic birth in the granular cell layer, and increased neuronal plasticity in the hippocampus and cerebral cortex. These findings, for the first time, demonstrate the possibility of therapeutic treatment of AD and related disorders by peripheral administration of a peptide corresponding to a biologically active region of CNTF.
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Affiliation(s)
- Julie Blanchard
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, 10314, USA.
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