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Wang Y, Zhu Y, Li W, Yan S, Li C, Ma K, Hu M, Du C, Fu L, Sun J, Zhang CX. Synaptotagmin-11 Inhibits Synaptic Vesicle Endocytosis via Endophilin A1. J Neurosci 2023; 43:6230-6248. [PMID: 37474308 PMCID: PMC10490507 DOI: 10.1523/jneurosci.1348-21.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 05/12/2023] [Accepted: 06/02/2023] [Indexed: 07/22/2023] Open
Abstract
Synaptic vesicle (SV) endocytosis is a critical and well-regulated process for the maintenance of neurotransmission. We previously reported that synaptotagmin-11 (Syt11), an essential non-Ca2+-binding Syt associated with brain diseases, inhibits neuronal endocytosis (Wang et al., 2016). Here, we found that Syt11 deficiency caused accelerated SV endocytosis and vesicle recycling under sustained stimulation and led to the abnormal membrane partition of synaptic proteins in mouse hippocampal boutons of either sex. Furthermore, our study revealed that Syt11 has direct but Ca2+-independent binding with endophilin A1 (EndoA1), a membrane curvature sensor and endocytic protein recruiter, with high affinity. EndoA1-knockdown significantly reversed Syt11-KO phenotype, identifying EndoA1 as a main inhibitory target of Syt11 during SV endocytosis. The N-terminus of EndoA1 and the C2B domain of Syt11 were responsible for this interaction. A peptide (amino acids 314-336) derived from the Syt11 C2B efficiently blocked Syt11-EndoA1 binding both in vitro and in vivo Application of this peptide inhibited SV endocytosis in WT hippocampal neurons but not in EndoA1-knockdown neurons. Moreover, intracellular application of this peptide in mouse calyx of Held terminals of either sex effectively hampered both fast and slow SV endocytosis at physiological temperature. We thus propose that Syt11 ensures the precision of protein retrieval during SV endocytosis by inhibiting EndoA1 function at neuronal terminals.SIGNIFICANCE STATEMENT Endocytosis is a key stage of synaptic vesicle (SV) recycling. SV endocytosis retrieves vesicular membrane and protein components precisely to support sustained neurotransmission. However, the molecular mechanisms underlying the regulation of SV endocytosis remain elusive. Here, we reported that Syt11-KO accelerated SV endocytosis and impaired membrane partition of synaptic proteins. EndoA1 was identified as a main inhibitory target of Syt11 during SV endocytosis. Our study reveals a novel inhibitory mechanism of SV endocytosis in preventing hyperactivation of endocytosis, potentially safeguarding the recycling of synaptic proteins during sustained neurotransmission.
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Affiliation(s)
- Yalong Wang
- Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences; CAS Key Laboratory of Brain Connectome and Manipulation; Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, Guangdong 518055, China
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Ying Zhu
- State Key Laboratory of Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Wanru Li
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Shuxin Yan
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Chao Li
- State Key Laboratory of Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Kunpeng Ma
- Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences; CAS Key Laboratory of Brain Connectome and Manipulation; Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, Guangdong 518055, China
| | - Meiqin Hu
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109
| | - Cuilian Du
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Lei Fu
- Academy of Pharmacy, Xi'an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
| | - Jianyuan Sun
- Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences; CAS Key Laboratory of Brain Connectome and Manipulation; Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, Guangdong 518055, China
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, 100069, China
- State Key Laboratory of Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Claire Xi Zhang
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, 100069, China
- Academy of Pharmacy, Xi'an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
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2
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Cheng K, Huang C, Hsieh T, Chiang H. Disrupted cellular calcium homeostasis is responsible for Aβ‐induced learning and memory damage and lifespan shortening in a model of Aβ transgenic fly. IUBMB Life 2022; 74:754-762. [DOI: 10.1002/iub.2621] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 04/11/2022] [Indexed: 12/27/2022]
Affiliation(s)
- Kuan‐Chung Cheng
- Department of Pharmacology, College of Medicine National Cheng‐Kung University Tainan Taiwan
- Institute of Basic Medical Sciences, College of Medicine National Cheng‐Kung University Tainan Taiwan
| | - Chih‐Yuan Huang
- Division of Nephrology, Department of Internal Medicine Ditmanson Medical Foundation Chia‐Yi Christian Hospital Chiayi Taiwan
- Department of Sport Management, College of Recreation and Health Management Chia Nan University of Pharmacy and Science Tainan Taiwan
| | - Tsung‐Chi Hsieh
- Department of Pharmacology, College of Medicine National Cheng‐Kung University Tainan Taiwan
- Institute of Basic Medical Sciences, College of Medicine National Cheng‐Kung University Tainan Taiwan
- Brain Research Center National Tsing Hua University Hsinchu City Taiwan
| | - Hsueh‐Cheng Chiang
- Department of Pharmacology, College of Medicine National Cheng‐Kung University Tainan Taiwan
- Institute of Basic Medical Sciences, College of Medicine National Cheng‐Kung University Tainan Taiwan
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3
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Gomis Perez C, Dudzinski NR, Rouches M, Landajuela A, Machta B, Zenisek D, Karatekin E. Rapid propagation of membrane tension at retinal bipolar neuron presynaptic terminals. SCIENCE ADVANCES 2022; 8:eabl4411. [PMID: 34985955 DOI: 10.1126/sciadv.abl4411] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Many cellular activities, such as cell migration, cell division, phagocytosis, and exo-endocytosis, generate and are regulated by membrane tension gradients. Membrane tension gradients drive membrane flows, but there is controversy over how rapidly plasma membrane flow can relax tension gradients. Here, we show that membrane tension can propagate rapidly or slowly, spanning orders of magnitude in speed, depending on the cell type. In a neuronal terminal specialized for rapid synaptic vesicle turnover, membrane tension equilibrates within seconds. By contrast, membrane tension does not propagate in neuroendocrine adrenal chromaffin cells secreting catecholamines. Stimulation of exocytosis causes a rapid, global decrease in the synaptic terminal membrane tension, which recovers slowly due to endocytosis. Thus, membrane flow and tension equilibration may be adapted to distinct membrane recycling requirements.
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Affiliation(s)
- Carolina Gomis Perez
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
- Nanobiology Institute, Yale University, West Haven, CT, USA
| | - Natasha R Dudzinski
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
- Nanobiology Institute, Yale University, West Haven, CT, USA
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT, USA
| | - Mason Rouches
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
- Systems Biology Institute, Yale University, West Haven, CT, USA
| | - Ane Landajuela
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
- Nanobiology Institute, Yale University, West Haven, CT, USA
| | - Benjamin Machta
- Systems Biology Institute, Yale University, West Haven, CT, USA
- Department of Physics, Yale University, New Haven, CT, USA
| | - David Zenisek
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT, USA
- Kavli Institute for Neuroscience, Yale University, New Haven, CT, USA
- Department of Neuroscience, Yale University, New Haven, CT, USA
- Department of Ophthalmology and Visual Sciences, Yale University, New Haven, CT, USA
| | - Erdem Karatekin
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
- Nanobiology Institute, Yale University, West Haven, CT, USA
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
- Université de Paris, SPPIN-Saints-Pères Paris Institute for the Neurosciences, Centre National de la Recherche Scientifique (CNRS), Paris F-75006, France
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Chen D, Yu W, Aitken L, Gunn-Moore F. Willin/FRMD6: A Multi-Functional Neuronal Protein Associated with Alzheimer's Disease. Cells 2021; 10:cells10113024. [PMID: 34831245 PMCID: PMC8616527 DOI: 10.3390/cells10113024] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/24/2021] [Accepted: 10/25/2021] [Indexed: 12/18/2022] Open
Abstract
The FERM domain-containing protein 6 (FRMD6), also known as Willin, is an upstream regulator of Hippo signaling that has recently been shown to modulate actin cytoskeleton dynamics and mechanical phenotype of neuronal cells through ERK signaling. Physiological functions of Willin/FRMD6 in the nervous system include neuronal differentiation, myelination, nerve injury repair, and vesicle exocytosis. The newly established neuronal role of Willin/FRMD6 is of particular interest given the mounting evidence suggesting a role for Willin/FRMD6 in Alzheimer's disease (AD), including a series of genome wide association studies that position Willin/FRMD6 as a novel AD risk gene. Here we describe recent findings regarding the role of Willin/FRMD6 in the nervous system and its actions in cellular perturbations related to the pathogenesis of AD.
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5
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Kudryashova IV. The Reorganization of the Actin Matrix as a Factor of Presynaptic Plasticity. NEUROCHEM J+ 2021. [DOI: 10.1134/s1819712421030089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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6
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Iuliano M, Seeley C, Sapp E, Jones EL, Martin C, Li X, DiFiglia M, Kegel-Gleason KB. Disposition of Proteins and Lipids in Synaptic Membrane Compartments Is Altered in Q175/Q7 Huntington's Disease Mouse Striatum. Front Synaptic Neurosci 2021; 13:618391. [PMID: 33815086 PMCID: PMC8013775 DOI: 10.3389/fnsyn.2021.618391] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 02/24/2021] [Indexed: 12/14/2022] Open
Abstract
Dysfunction at synapses is thought to be an early change contributing to cognitive, psychiatric and motor disturbances in Huntington's disease (HD). In neurons, mutant Huntingtin collects in aggregates and distributes to the same sites as wild-type Huntingtin including on membranes and in synapses. In this study, we investigated the biochemical integrity of synapses in HD mouse striatum. We performed subcellular fractionation of striatal tissue from 2 and 6-month old knock-in Q175/Q7 HD and Q7/Q7 mice. Compared to striata of Q7/Q7 mice, proteins including GLUT3, Na+/K+ ATPase, NMDAR 2b, PSD95, and VGLUT1 had altered distribution in Q175/Q7 HD striata of 6-month old mice but not 2-month old mice. These proteins are found on plasma membranes and pre- and postsynaptic membranes supporting hypotheses that functional changes at synapses contribute to cognitive and behavioral symptoms of HD. Lipidomic analysis of mouse fractions indicated that compared to those of wild-type, fractions 1 and 2 of 6 months Q175/Q7 HD had altered levels of two species of PIP2, a phospholipid involved in synaptic signaling, increased levels of cholesterol ester and decreased cardiolipin species. At 2 months, increased levels of species of acylcarnitine, phosphatidic acid and sphingomyelin were measured. EM analysis showed that the contents of fractions 1 and 2 of Q7/Q7 and Q175/Q7 HD striata had a mix of isolated synaptic vesicles, vesicle filled axon terminals singly or in clusters, and ER and endosome-like membranes. However, those of Q175/Q7 striata contained significantly fewer and larger clumps of particles compared to those of Q7/Q7. Human HD postmortem putamen showed differences from control putamen in subcellular distribution of two proteins (Calnexin and GLUT3). Our biochemical, lipidomic and EM analysis show that the presence of the HD mutation conferred age dependent disruption of localization of synaptic proteins and lipids important for synaptic function. Our data demonstrate concrete biochemical changes suggesting altered integrity of synaptic compartments in HD mice that may mirror changes in HD patients and presage cognitive and psychiatric changes that occur in premanifest HD.
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7
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Harper CB, Smillie KJ. Current molecular approaches to investigate pre-synaptic dysfunction. J Neurochem 2021; 157:107-129. [PMID: 33544872 DOI: 10.1111/jnc.15316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/19/2022]
Abstract
Over the course of the last few decades it has become clear that many neurodevelopmental and neurodegenerative disorders have a synaptic defect, which contributes to pathogenicity. A rise in new techniques, and in particular '-omics'-based methods providing large datasets, has led to an increase in potential proteins and pathways implicated in synaptic function and related disorders. Additionally, advancements in imaging techniques have led to the recent discovery of alternative modes of synaptic vesicle recycling. This has resulted in a lack of clarity over the precise role of different pathways in maintaining synaptic function and whether these new pathways are dysfunctional in neurodevelopmental and neurodegenerative disorders. A greater understanding of the molecular detail of pre-synaptic function in health and disease is key to targeting new proteins and pathways for novel treatments and the variety of new techniques currently available provides an ideal opportunity to investigate these functions. This review focuses on techniques to interrogate pre-synaptic function, concentrating mainly on synaptic vesicle recycling. It further examines techniques to determine the underlying molecular mechanism of pre-synaptic dysfunction and discusses methods to identify molecular targets, along with protein-protein interactions and cellular localization. In combination, these techniques will provide an expanding and more complete picture of pre-synaptic function. With the application of recent technological advances, we are able to resolve events with higher spatial and temporal resolution, leading research towards a greater understanding of dysfunction at the presynapse and the role it plays in pathogenicity.
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Affiliation(s)
- Callista B Harper
- Centre for Discovery Brain Sciences, University of Edinburgh, Scotland, UK
| | - Karen J Smillie
- Centre for Discovery Brain Sciences, University of Edinburgh, Scotland, UK
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8
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Xiang W, Long Z, Zeng J, Zhu X, Yuan M, Wu J, Wu Y, Liu L. Mechanism of Radix Rhei Et Rhizome Intervention in Cerebral Infarction: A Research Based on Chemoinformatics and Systematic Pharmacology. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2021; 2021:6789835. [PMID: 34531920 PMCID: PMC8440083 DOI: 10.1155/2021/6789835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 08/13/2021] [Indexed: 02/05/2023]
Abstract
OBJECTIVE To explore the therapeutic targets, network modules, and coexpressed genes of Radix Rhei Et Rhizome intervention in cerebral infarction (CI), and to predict significant biological processes and pathways through network pharmacology. To explore the differential proteins of Radix Rhei Et Rhizome intervention in CI, conduct bioinformatics verification, and initially explain the possible therapeutic mechanism of Radix Rhei Et Rhizome intervention in CI through proteomics. METHODS The TCM database was used to predict the potential compounds of Radix Rhei Et Rhizome, and the PharmMapper was used to predict its potential targets. GeneCards and OMIM were used to search for CI-related genes. Cytoscape was used to construct a protein-protein interaction (PPI) network and to screen out core genes and detection network modules. Then, DAVID and Metascape were used for enrichment analysis. After that, in-depth analysis of the proteomics data was carried out to further explore the mechanism of Radix Rhei Et Rhizome intervention in CI. RESULTS (1) A total of 14 Radix Rhei Et Rhizome potential components and 425 potential targets were obtained. The core components include sennoside A, palmidin A, emodin, toralactone, and so on. The potential targets were combined with 297 CI genes to construct a PPI network. The targets shared by Radix Rhei Et Rhizome and CI include ALB, AKT1, MMP9, IGF1, CASP3, etc. The biological processes that Radix Rhei Et Rhizome may treat CI include platelet degranulation, cell migration, fibrinolysis, platelet activation, hypoxia, angiogenesis, endothelial cell apoptosis, coagulation, and neuronal apoptosis. The signaling pathways include Ras, PI3K-Akt, TNF, FoxO, HIF-1, and Rap1 signaling pathways. (2) Proteomics shows that the top 20 proteins in the differential protein PPI network were Syp, Syn1, Mbp, Gap43, Aif1, Camk2a, Syt1, Calm1, Calb1, Nsf, Nefl, Hspa5, Nefh, Ncam1, Dcx, Unc13a, Mapk1, Syt2, Dnm1, and Cltc. Differential protein enrichment results show that these proteins may be related to synaptic vesicle cycle, vesicle-mediated transport in synapse, presynaptic endocytosis, synaptic vesicle endocytosis, axon guidance, calcium signaling pathway, and so on. CONCLUSION This study combined network pharmacology and proteomics to explore the main material basis of Radix Rhei Et Rhizome for the treatment of CI such as sennoside A, palmidin A, emodin, and toralactone. The mechanism may be related to the regulation of biological processes (such as synaptic vesicle cycle, vesicle-mediated transport in synapse, presynaptic endocytosis, and synaptic vesicle endocytosis) and signaling pathways (such as Ras, PI3K-Akt, TNF, FoxO, HIF-1, Rap1, and axon guidance).
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Affiliation(s)
- Wang Xiang
- The Affiliated Hospital of Guilin Medical University, Guilin, Guangxi Province, China
| | - Zhiyong Long
- Shantou University Medical College, Shantou University, Shantou, Guangdong, China
| | - Jinsong Zeng
- The First Affiliated Hospital of Hunan University of Chinese Medicine, Changsha, Hunan Province, China
- Hunan University of Chinese Medicine, Changsha, Hunan Province, China
| | - Xiaofei Zhu
- Hunan University of Chinese Medicine, Changsha, Hunan Province, China
| | - Mengxia Yuan
- Shantou University Medical College, Shantou University, Shantou, Guangdong, China
| | - Jiamin Wu
- Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yonghe Wu
- Hunan University of Chinese Medicine, Changsha, Hunan Province, China
| | - Liang Liu
- Hunan University of Chinese Medicine, Changsha, Hunan Province, China
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9
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Li TN, Chen YJ, Lu TY, Wang YT, Lin HC, Yao CK. A positive feedback loop between Flower and PI(4,5)P 2 at periactive zones controls bulk endocytosis in Drosophila. eLife 2020; 9:60125. [PMID: 33300871 PMCID: PMC7748424 DOI: 10.7554/elife.60125] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 12/09/2020] [Indexed: 01/01/2023] Open
Abstract
Synaptic vesicle (SV) endocytosis is coupled to exocytosis to maintain SV pool size and thus neurotransmitter release. Intense stimulation induces activity-dependent bulk endocytosis (ADBE) to recapture large quantities of SV constituents in large endosomes from which SVs reform. How these consecutive processes are spatiotemporally coordinated remains unknown. Here, we show that Flower Ca2+ channel-dependent phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) compartmentalization governs control of these processes in Drosophila. Strong stimuli trigger PI(4,5)P2 microdomain formation at periactive zones. Upon exocytosis, Flower translocates from SVs to periactive zones, where it increases PI(4,5)P2 levels via Ca2+ influxes. Remarkably, PI(4,5)P2 directly enhances Flower channel activity, thereby establishing a positive feedback loop for PI(4,5)P2 microdomain compartmentalization. PI(4,5)P2 microdomains drive ADBE and SV reformation from bulk endosomes. PI(4,5)P2 further retrieves Flower to bulk endosomes, terminating endocytosis. We propose that the interplay between Flower and PI(4,5)P2 is the crucial spatiotemporal cue that couples exocytosis to ADBE and subsequent SV reformation.
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Affiliation(s)
- Tsai-Ning Li
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Yu-Jung Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Ting-Yi Lu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - You-Tung Wang
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Hsin-Chieh Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Chi-Kuang Yao
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.,Neuroscience Program of Academia Sinica, Academia Sinica, Taipei, Taiwan.,Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan
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10
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Orlando M, Schmitz D, Rosenmund C, Herman MA. Calcium-Independent Exo-endocytosis Coupling at Small Central Synapses. Cell Rep 2020; 29:3767-3774.e3. [PMID: 31851910 DOI: 10.1016/j.celrep.2019.11.060] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 10/08/2019] [Accepted: 11/14/2019] [Indexed: 12/27/2022] Open
Abstract
At presynaptic terminals, neurotransmitters are released by synaptic vesicle exocytosis at the active zone. In order to maintain efficient neurotransmission and proper synaptic structure, sites of vesicle fusion must be cleared rapidly by endocytosis. Therefore, the coupling of exo- and endocytosis is crucial. Despite many years of research, the exact molecular and biophysical requirements for the coupling of exo- and endocytosis remain unclear. We investigate whether endocytosis can be triggered in a calcium-independent fashion by evoking calcium-independent exocytosis using a hypertonic sucrose solution. We demonstrate that endocytosis can be triggered, in the absence of calcium influx, in a clathrin-independent manner that relies on actin polymerization. Our findings point to a central role of membrane tension dependent on actin for efficient coupling of exo- and endocytosis.
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Affiliation(s)
- Marta Orlando
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universitäts Berlin and Humboldt-Universität zu Berlin, and Berlin Institute of Health, NeuroCure Cluster of Excellence, Institut für Neurophysiologie, Charitéplatz 1, 10117 Berlin, Germany
| | - Dietmar Schmitz
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universitäts Berlin and Humboldt-Universität zu Berlin, and Berlin Institute of Health, NeuroCure Cluster of Excellence, German Center for Neurodegenerative Diseases (DZNE), Charitéplatz 1, 10117 Berlin, Germany; Einstein Center for Neurosciences (ECN), 10117 Berlin, Germany; Bernstein Center for Computational Neuroscience (BCCN) Berlin, 10115 Berlin, Germany; Max-Delbruck-Centrum (MDC) for Molecular Medicine, 13125 Berlin, Germany
| | - Christian Rosenmund
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universitäts Berlin and Humboldt-Universität zu Berlin, and Berlin Institute of Health, NeuroCure Cluster of Excellence, Institut für Neurophysiologie, Charitéplatz 1, 10117 Berlin, Germany; Einstein Center for Neurosciences (ECN), 10117 Berlin, Germany.
| | - Melissa A Herman
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universitäts Berlin and Humboldt-Universität zu Berlin, and Berlin Institute of Health, NeuroCure Cluster of Excellence, Institut für Neurophysiologie, Charitéplatz 1, 10117 Berlin, Germany.
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11
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Beijer D, Sisto A, Van Lent J, Baets J, Timmerman V. Defects in Axonal Transport in Inherited Neuropathies. J Neuromuscul Dis 2020; 6:401-419. [PMID: 31561383 PMCID: PMC6918914 DOI: 10.3233/jnd-190427] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Axonal transport is a highly complex process essential for sustaining proper neuronal functioning. Disturbances can result in an altered neuronal homeostasis, aggregation of cargoes, and ultimately a dying-back degeneration of neurons. The impact of dysfunction in axonal transport is shown by genetic defects in key proteins causing a broad spectrum of neurodegenerative diseases, including inherited peripheral neuropathies. In this review, we provide an overview of the cytoskeletal components, molecular motors and adaptor proteins involved in axonal transport mechanisms and their implication in neuronal functioning. In addition, we discuss the involvement of axonal transport dysfunction in neurodegenerative diseases with a particular focus on inherited peripheral neuropathies. Lastly, we address some recent scientific advances most notably in therapeutic strategies employed in the area of axonal transport, patient-derived iPSC models, in vivo animal models, antisense-oligonucleotide treatments, and novel chemical compounds.
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Affiliation(s)
- Danique Beijer
- Neurogenetics Research Group, Department of Medical Sciences, University of Antwerp, Antwerpen, Belgium.,Neurogenetics Laboratory, Institute Born Bunge, Antwerpen, Belgium
| | - Angela Sisto
- Peripheral Neuropathy Research Group, Department of Biomedical Sciences, University of Antwerp, Antwerpen, Belgium.,Neurogenetics Laboratory, Institute Born Bunge, Antwerpen, Belgium
| | - Jonas Van Lent
- Peripheral Neuropathy Research Group, Department of Biomedical Sciences, University of Antwerp, Antwerpen, Belgium.,Neurogenetics Laboratory, Institute Born Bunge, Antwerpen, Belgium
| | - Jonathan Baets
- Neurogenetics Research Group, Department of Medical Sciences, University of Antwerp, Antwerpen, Belgium.,Neurogenetics Laboratory, Institute Born Bunge, Antwerpen, Belgium.,Neurology Department, University Hospital Antwerp, Antwerpen, Belgium
| | - Vincent Timmerman
- Peripheral Neuropathy Research Group, Department of Biomedical Sciences, University of Antwerp, Antwerpen, Belgium.,Neurogenetics Laboratory, Institute Born Bunge, Antwerpen, Belgium
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12
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Cohen AE, Shi Z. Do Cell Membranes Flow Like Honey or Jiggle Like Jello? Bioessays 2019; 42:e1900142. [DOI: 10.1002/bies.201900142] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 10/31/2019] [Indexed: 12/24/2022]
Affiliation(s)
- Adam E. Cohen
- Departments of Chemistry and Chemical Biology and PhysicsHarvard University Cambridge MA USA
- Howard Hughes Medical Institute Chevy Chase MD USA
| | - Zheng Shi
- Departments of Chemistry and Chemical Biology and PhysicsHarvard University Cambridge MA USA
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13
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Kampf LL, Schneider R, Gerstner L, Thünauer R, Chen M, Helmstädter M, Amar A, Onuchic-Whitford AC, Loza Munarriz R, Berdeli A, Müller D, Schrezenmeier E, Budde K, Mane S, Laricchia KM, Rehm HL, MacArthur DG, Lifton RP, Walz G, Römer W, Bergmann C, Hildebrandt F, Hermle T. TBC1D8B Mutations Implicate RAB11-Dependent Vesicular Trafficking in the Pathogenesis of Nephrotic Syndrome. J Am Soc Nephrol 2019; 30:2338-2353. [PMID: 31732614 DOI: 10.1681/asn.2019040414] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 08/07/2019] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Mutations in about 50 genes have been identified as monogenic causes of nephrotic syndrome, a frequent cause of CKD. These genes delineated the pathogenetic pathways and rendered significant insight into podocyte biology. METHODS We used whole-exome sequencing to identify novel monogenic causes of steroid-resistant nephrotic syndrome (SRNS). We analyzed the functional significance of an SRNS-associated gene in vitro and in podocyte-like Drosophila nephrocytes. RESULTS We identified hemizygous missense mutations in the gene TBC1D8B in five families with nephrotic syndrome. Coimmunoprecipitation assays indicated interactions between TBC1D8B and active forms of RAB11. Silencing TBC1D8B in HEK293T cells increased basal autophagy and exocytosis, two cellular functions that are independently regulated by RAB11. This suggests that TBC1D8B plays a regulatory role by inhibiting endogenous RAB11. Coimmunoprecipitation assays showed TBC1D8B also interacts with the slit diaphragm protein nephrin, and colocalizes with it in immortalized cell lines. Overexpressed murine Tbc1d8b with patient-derived mutations had lower affinity for endogenous RAB11 and nephrin compared with wild-type Tbc1d8b protein. Knockdown of Tbc1d8b in Drosophila impaired function of the podocyte-like nephrocytes, and caused mistrafficking of Sns, the Drosophila ortholog of nephrin. Expression of Rab11 RNAi in nephrocytes entailed defective delivery of slit diaphragm protein to the membrane, whereas RAB11 overexpression revealed a partial phenotypic overlap to Tbc1d8b loss of function. CONCLUSIONS Novel mutations in TBC1D8B are monogenic causes of SRNS. This gene inhibits RAB11. Our findings suggest that RAB11-dependent vesicular nephrin trafficking plays a role in the pathogenesis of nephrotic syndrome.
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Affiliation(s)
- Lina L Kampf
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Ronen Schneider
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Lea Gerstner
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Roland Thünauer
- Signalling Research Centres BIOSS and CIBSS and Faculty of Biology, University of Freiburg, Freiburg, Germany.,Advanced Light and Fluorescence Microscopy Facility, Centre for Structural Systems Biology (CSSB) and University of Hamburg, Hamburg, Germany
| | - Mengmeng Chen
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Martin Helmstädter
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Ali Amar
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Ana C Onuchic-Whitford
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts.,Renal Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | | | - Afig Berdeli
- Department of Pediatrics, Molecular Medicine Laboratory, Ege University, Izmir, Turkey
| | - Dominik Müller
- Department of Pediatric Nephrology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Eva Schrezenmeier
- Department of Nephrology and Medical Intensive Care, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Klemens Budde
- Department of Nephrology and Medical Intensive Care, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Shrikant Mane
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut
| | - Kristen M Laricchia
- Broad Center for Mendelian Genomics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge
| | - Heidi L Rehm
- Broad Center for Mendelian Genomics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge
| | - Daniel G MacArthur
- Broad Center for Mendelian Genomics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge
| | - Richard P Lifton
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut.,Laboratory of Human Genetics and Genomics, The Rockefeller University, New York, New York
| | - Gerd Walz
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Winfried Römer
- Signalling Research Centres BIOSS and CIBSS and Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Carsten Bergmann
- Center for Human Genetics, Mainz, Germany.,Center for Human Genetics, Bioscientia, Ingelheim, Germany; and.,Department of Medicine, University Hospital Freiburg, Freiburg, Germany
| | - Friedhelm Hildebrandt
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts;
| | - Tobias Hermle
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany;
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14
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Courtney NA, Bao H, Briguglio JS, Chapman ER. Synaptotagmin 1 clamps synaptic vesicle fusion in mammalian neurons independent of complexin. Nat Commun 2019; 10:4076. [PMID: 31501440 PMCID: PMC6733930 DOI: 10.1038/s41467-019-12015-w] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 08/12/2019] [Indexed: 02/01/2023] Open
Abstract
Synaptic vesicle (SV) exocytosis is mediated by SNARE proteins. Reconstituted SNAREs are constitutively active, so a major focus has been to identify fusion clamps that regulate their activity in synapses: the primary candidates are synaptotagmin (syt) 1 and complexin I/II. Syt1 is a Ca2+ sensor for SV release that binds Ca2+ via tandem C2-domains, C2A and C2B. Here, we first determined whether these C2-domains execute distinct functions. Remarkably, the C2B domain profoundly clamped all forms of SV fusion, despite synchronizing residual evoked release and rescuing the readily-releasable pool. Release was strongly enhanced by an adjacent C2A domain, and by the concurrent binding of complexin to trans-SNARE complexes. Knockdown of complexin had no impact on C2B-mediated clamping of fusion. We postulate that the C2B domain of syt1, independent of complexin, is the molecular clamp that arrests SVs prior to Ca2+-triggered fusion.
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Affiliation(s)
- Nicholas A Courtney
- Department of Neuroscience and Howard Hughes Medical Institute, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
| | - Huan Bao
- Department of Neuroscience and Howard Hughes Medical Institute, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
| | - Joseph S Briguglio
- Department of Neuroscience and Howard Hughes Medical Institute, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
| | - Edwin R Chapman
- Department of Neuroscience and Howard Hughes Medical Institute, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA.
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15
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SIV-Mediated Synaptic Dysfunction Is Associated with an Increase in Synapsin Site 1 Phosphorylation and Impaired PP2A Activity. J Neurosci 2019; 39:7006-7018. [PMID: 31270156 DOI: 10.1523/jneurosci.0178-19.2019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 05/31/2019] [Accepted: 06/22/2019] [Indexed: 11/21/2022] Open
Abstract
Although the reduction of viral loads in people with HIV undergoing combination antiretroviral therapy has mitigated AIDS-related symptoms, the prevalence of neurological impairments has remained unchanged. HIV-associated CNS dysfunction includes impairments in memory, attention, memory processing, and retrieval. Here, we show a significant site-specific increase in the phosphorylation of Syn I serine 9, site 1, in the frontal cortex lysates and synaptosome preparations of male rhesus macaques infected with simian immunodeficiency virus (SIV) but not in uninfected or SIV-infected antiretroviral therapy animals. Furthermore, we found that a lower protein phosphatase 2A (PP2A) activity, a phosphatase responsible for Syn I (S9) dephosphorylation, is primarily associated with the higher S9 phosphorylation in the frontal cortex of SIV-infected macaques. Comparison of brain sections confirmed higher Syn I (S9) in the frontal cortex and greater coexpression of Syn I and PP2A A subunit, which was observed as perinuclear aggregates in the somata of the frontal cortex of SIV-infected macaques. Synaptosomes from SIV-infected animals were physiologically tested using a synaptic vesicle endocytosis assay and FM4-64 dye showing a significantly higher baseline depolarization levels in synaptosomes of SIV+-infected than uninfected control or antiretroviral therapy animals. A PP2A-activating FDA-approved drug, FTY720, decreased the higher synaptosome depolarization in SIV-infected animals. Our results suggest that an impaired distribution and lower activity of serine/threonine phosphatases in the context of HIV infection may cause an indirect effect on the phosphorylation levels of essential proteins involving in synaptic transmission, supporting the occurrence of specific impairments in the synaptic activity during SIV infection.SIGNIFICANCE STATEMENT Even with antiretroviral therapy, neurocognitive deficits, including impairments in attention, memory processing, and retrieval, are still major concerns in people living with HIV. Here, we used the rhesus macaque simian immunodeficiency virus model with and without antiretroviral therapy to study the dynamics of phosphorylation of key amino acid residues of synapsin I, which critically impacts synaptic vesicle function. We found a significant increase in synapsin I phosphorylation at serine 9, which was driven by dysfunction of serine/threonine protein phosphatase 2A in the nerve terminals. Our results suggest that an impaired distribution and lower activity of serine/threonine phosphatases in the context of HIV infection may cause an indirect effect on the phosphorylation levels of essential proteins involved in synaptic transmission.
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16
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Karatekin E, Rothman JE. FEBS Letters Special Issue on Exocytosis and Endocytosis. FEBS Lett 2019; 592:3477-3479. [PMID: 30417372 DOI: 10.1002/1873-3468.13274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Erdem Karatekin
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA.,Nanobiology Institute, Yale University, West Haven, CT, USA.,Centre National de la Recherche Scientifique (CNRS), Paris, France
| | - James E Rothman
- Nanobiology Institute, Yale University, West Haven, CT, USA.,Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA.,Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, UK
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17
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Lee SE, Jeong S, Lee U, Chang S. SGIP1α functions as a selective endocytic adaptor for the internalization of synaptotagmin 1 at synapses. Mol Brain 2019; 12:41. [PMID: 31053155 PMCID: PMC6499997 DOI: 10.1186/s13041-019-0464-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 04/16/2019] [Indexed: 11/10/2022] Open
Abstract
Proper sorting of exocytosed synaptic vesicle (SV) proteins into individual SVs during endocytosis is of the utmost importance for the fidelity of subsequent neurotransmission. Recent studies suggest that each SV protein is sorted into individual SVs by its own dedicated adaptors as well as by association between SV proteins. The SH3-containing GRB2-like protein 3-interacting protein 1 (SGIP1), an ortholog of Fer/Cip4 homology domain-only (FCHo) proteins, contains a μ-homology domain (μHD) and binds AP-2 and Eps15, thus functioning as an endocytic regulator of clathrin-mediated endocytosis (CME). Its longest isoform SGIP1α is predominantly expressed in the brain but the functional significance of SGIP1 in SV recycling remains unknown. Here, we found that SGIP1α, a brain-specific long isoform of SGIP1 binds synaptotagmin1 (Syt1) via its μHD and promotes the internalization of Syt1 on the neuronal surface. The small hairpin RNA (shRNA)-mediated knockdown (KD) of SGIP1α caused selective impairment of Syt1 internalization at hippocampal synapses and it was fully rescued by coexpression of the shRNA-resistant form of SGIP1α in KD neurons. We further found that the μHD of SGIP1α is structurally similar to those of AP-2 and stonin2, and mutations at Trp771 and Lys781, which correspond to Syt1-recognition motifs of AP-2 and stonin2, to Ala bound less efficiently to Syt1 and failed to rescue the endocytic defect of Syt1 caused by KD. Our results indicate that SGIP1α is an endocytic adaptor dedicated to the retrieval of surface-stranded Syt1. Since endocytic sorting of Syt1 is also mediated by the overlapping activities of synaptic vesicle glycoprotein 2A/B (SV2A/B) and stonin2, our results suggest that complementary fail-safe mechanism by these proteins ensures high fidelity of Syt1 retrieval.
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Affiliation(s)
- Sang-Eun Lee
- Department of Physiology and Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Soomin Jeong
- Department of Physiology and Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Unghwi Lee
- Department of Physiology and Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Sunghoe Chang
- Department of Physiology and Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, 03080, South Korea.
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18
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Karatekin E. Toward a unified picture of the exocytotic fusion pore. FEBS Lett 2018; 592:3563-3585. [PMID: 30317539 PMCID: PMC6353554 DOI: 10.1002/1873-3468.13270] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 09/30/2018] [Accepted: 10/10/2018] [Indexed: 11/07/2022]
Abstract
Neurotransmitter and hormone release involve calcium-triggered fusion of a cargo-loaded vesicle with the plasma membrane. The initial connection between the fusing membranes, called the fusion pore, can evolve in various ways, including rapid dilation to allow full cargo release, slow expansion, repeated opening-closing and resealing. Pore dynamics determine the kinetics of cargo release and the mode of vesicle recycling, but how these processes are controlled is poorly understood. Previous reconstitutions could not monitor single pores, limiting mechanistic insight they could provide. Recently developed nanodisc-based fusion assays allow reconstitution and monitoring of single pores with unprecedented detail and hold great promise for future discoveries. They recapitulate various aspects of exocytotic fusion pores, but comparison is difficult because different approaches suggested very different exocytotic fusion pore properties, even for the same cell type. In this Review, I discuss how most of the data can be reconciled, by recognizing how different methods probe different aspects of the same fusion process. The resulting picture is that fusion pores have broadly distributed properties arising from stochastic processes which can be modulated by physical constraints imposed by proteins, lipids and membranes.
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Affiliation(s)
- Erdem Karatekin
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
- Nanobiology Institute, Yale University, West Haven, CT, USA
- Centre National de la Recherche Scientifique (CNRS), Paris, France
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19
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Merighi A. Costorage of High Molecular Weight Neurotransmitters in Large Dense Core Vesicles of Mammalian Neurons. Front Cell Neurosci 2018; 12:272. [PMID: 30186121 PMCID: PMC6110924 DOI: 10.3389/fncel.2018.00272] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 08/03/2018] [Indexed: 12/19/2022] Open
Abstract
It is today widely accepted that several types of high molecular weight (MW) neurotransmitters produced by neurons are synthesized at the cell body, selectively stored within large dense core vesicles (LDCVs) and anterogradely transported to terminals where they elicit their biological role(s). Among these molecules there are neuropeptides and neurotrophic factors, the main focus of this perspective article. I here first provide a brief resume of the state of art on neuronal secretion, with primary emphasis on the molecular composition and mechanism(s) of filling and release of LDCVs. Then, I discuss the perspectives and future directions of research in the field as regarding the synthesis and storage of multiple high MW transmitters in LDCVs and the possibility that a selective sorting of LDCVs occurs along different neuronal processes and/or their branches. I also consider the ongoing discussion that diverse types of neurons may contain LDCVs with different sets of integral proteins or dial in a different fashion with LDCVs containing the same cargo. In addition, I provide original data on the size of LDCVs in rat dorsal root ganglion neurons and their central terminals in the spinal cord after immunogold labeling for calcitonin gene-related peptide (CGRP), neuropeptide K, substance P, neurokinin A or somatostatin. These data corroborate the idea that, similarly to endocrine cells, LDCVs undergo a process of maturation which involves a homotypic fusion followed by a reduction in size and condensation of cargo. They also give support to the conjecture that release at terminals occurs by cavicapture, a process of partial fusion of the vesicle with the axolemma, accompanied by depletion of cargo and diminution of size.
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Affiliation(s)
- Adalberto Merighi
- Laboratory of Neurobiology, Department of Veterinary Sciences, University of Turin, Turin, Italy
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20
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Morris CE. Cytotoxic Swelling of Sick Excitable Cells - Impaired Ion Homeostasis and Membrane Tension Homeostasis in Muscle and Neuron. CURRENT TOPICS IN MEMBRANES 2018; 81:457-496. [PMID: 30243439 DOI: 10.1016/bs.ctm.2018.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
When they become simultaneously leaky to both Na+ and Cl-, excitable cells are vulnerable to potentially lethal cytotoxic swelling. Swelling ensues in spite of an isosmotic milieu because the entering ions add osmolytes to the cytoplasm's high concentration of impermeant anionic osmolytes. An influx of osmotically-obliged water is unavoidable. A cell that cannot stanch at least one the leaks will succumb to death by Donnan effect. "Sick excitable cells" are those injured through ischemia, trauma, inflammation, hyperactivity, genetically-impaired membrane skeletons and other insults, all of which foster bleb-damage to regions of the plasma membrane. Nav channels resident in damaged membrane exhibit left-shifted kinetics; the corresponding Nav window conductance constitutes a Na+-leak. In cortical neurons, sustained depolarization to ∼-20mV elicits a sustained lethal gCl. Underlying Vrest in skeletal muscle is a constitutively active gCl; not surprisingly therefore, dystrophic muscle fibers, which are prone to bleb damage and which exhibit Nav-leak and Na+-overload, are prone to cytotoxic swelling. To restore viability in cytotoxically swelling neurons and muscle, the imperative of fully functional ion homeostasis is well-recognized. However, as emphasized here, in a healthy excitable cell, fully functional membrane tension homeostasis is also imperative. ATPase-pumps keep plasma membrane batteries charged, and ATPase-motor proteins maintain membrane tone. In sick excitable cells, neither condition prevails.
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Affiliation(s)
- Catherine E Morris
- Senior Scientist Emeritus, Neuroscience, Ottawa Hospital Research Institute, Ottawa, ON, Canada
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21
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Zhu YH, Hyun J, Pan YZ, Hopper JE, Rizo J, Wu JQ. Roles of the fission yeast UNC-13/Munc13 protein Ync13 in late stages of cytokinesis. Mol Biol Cell 2018; 29:2259-2279. [PMID: 30044717 PMCID: PMC6249806 DOI: 10.1091/mbc.e18-04-0225] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cytokinesis is a complicated yet conserved step of the cell-division cycle that requires the coordination of multiple proteins and cellular processes. Here we describe a previously uncharacterized protein, Ync13, and its roles during fission yeast cytokinesis. Ync13 is a member of the UNC-13/Munc13 protein family, whose animal homologues are essential priming factors for soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex assembly during exocytosis in various cell types, but no roles in cytokinesis have been reported. We find that Ync13 binds to lipids in vitro and dynamically localizes to the plasma membrane at cell tips during interphase and at the division site during cytokinesis. Deletion of Ync13 leads to defective septation and exocytosis, uneven distribution of cell-wall enzymes and components of cell-wall integrity pathway along the division site and massive cell lysis during cell separation. Interestingly, loss of Ync13 compromises endocytic site selection at the division plane. Collectively, we find that Ync13 has a novel function as an UNC-13/Munc13 protein in coordinating exocytosis, endocytosis, and cell-wall integrity during fission yeast cytokinesis.
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Affiliation(s)
- Yi-Hua Zhu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| | - Joanne Hyun
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| | - Yun-Zu Pan
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390.,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - James E Hopper
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
| | - Josep Rizo
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390.,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Jian-Qiu Wu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210.,Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210
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