1
|
Spencer RKW, Smirnova YG, Soleimani A, Müller M. Transient pores in hemifusion diaphragms. Biophys J 2024; 123:2455-2475. [PMID: 38867448 DOI: 10.1016/j.bpj.2024.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 05/07/2024] [Accepted: 06/07/2024] [Indexed: 06/14/2024] Open
Abstract
Exchange of material across two membranes, as in the case of synaptic neurotransmitter release from a vesicle, involves the formation and poration of a hemifusion diaphragm (HD). The nontrivial geometry of the HD leads to environment-dependent control, regarding the stability and dynamics of the pores required for this kind of exocytosis. This work combines particle simulations, field-based calculations, and phenomenological modeling to explore the factors influencing the stability, dynamics, and possible control mechanisms of pores in HDs. We find that pores preferentially form at the HD rim, and that their stability is sensitive to a number of factors, including the three line tensions, membrane tension, HD size, and the ability of lipids to "flip-flop" across leaflets. Along with a detailed analysis of these factors, we discuss ways that vesicles or cells may use them to open and close pores and thereby quickly and efficiently transport material.
Collapse
Affiliation(s)
- Russell K W Spencer
- Institute for Theoretical Physics, Georg-August University, Göttingen, Germany.
| | - Yuliya G Smirnova
- Institute for Theoretical Physics, Georg-August University, Göttingen, Germany; Technische Universität Dortmund, Dortmund, Germany
| | - Alireza Soleimani
- Institute for Theoretical Physics, Georg-August University, Göttingen, Germany
| | - Marcus Müller
- Institute for Theoretical Physics, Georg-August University, Göttingen, Germany.
| |
Collapse
|
2
|
Chang HF, Schirra C, Pattu V, Krause E, Becherer U. Lytic granule exocytosis at immune synapses: lessons from neuronal synapses. Front Immunol 2023; 14:1177670. [PMID: 37275872 PMCID: PMC10233144 DOI: 10.3389/fimmu.2023.1177670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 05/09/2023] [Indexed: 06/07/2023] Open
Abstract
Regulated exocytosis is a central mechanism of cellular communication. It is not only the basis for neurotransmission and hormone release, but also plays an important role in the immune system for the release of cytokines and cytotoxic molecules. In cytotoxic T lymphocytes (CTLs), the formation of the immunological synapse is required for the delivery of the cytotoxic substances such as granzymes and perforin, which are stored in lytic granules and released via exocytosis. The molecular mechanisms of their fusion with the plasma membrane are only partially understood. In this review, we discuss the molecular players involved in the regulated exocytosis of CTL, highlighting the parallels and differences to neuronal synaptic transmission. Additionally, we examine the strengths and weaknesses of both systems to study exocytosis.
Collapse
|
3
|
Capella P, Asensio J, Troncoso M, Sosa MA, Seltzer AM. Evidence on differential role for alpha 1 and alpha 2 subtypes of AP-2 adaptin in the Central Nervous System. Neurosci Lett 2023; 808:137282. [PMID: 37127089 DOI: 10.1016/j.neulet.2023.137282] [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: 03/13/2023] [Revised: 04/24/2023] [Accepted: 04/28/2023] [Indexed: 05/03/2023]
Abstract
Two subtypes of alpha (α)subunits , α1and α2, belonging to AP-2 complex have been described in the central nervous system (CNS). The specific role of each subtype is still unclear. In this study, we evaluated the expression and interaction with cell membranes of both subtypes in the postnatal developing cerebral cortex and cerebellum in two rat strains that display distinct developmental features. We observed that α2 displays higher variations than α1 during development, and at lesser extent in the rats with delayed rate of development. Additionally, by in vitro binding assays we evaluated the interaction of α subunits with bovine brain membranes. Both subtypes displayed clear differences in their performance, maximum binding of α1 was higher and α2 reached it faster than α1. In addition, both subtypes displayed different binding to membranes when bivalent cations or nucleotides were added. We conclude that both subtypes interact differently with membranes and that they may play different roles in clathrin-mediated endocytosis in the CNS.
Collapse
Affiliation(s)
- P Capella
- Laboratorio de Biología y Fisiología Celular "Dr. Francisco Bertini"- Instituto de Histología y Embriología - FCM, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - J Asensio
- Plataforma de Neurobiología- Instituto de Histología y Embriología (CONICET), Mendoza. Argentina
| | - M Troncoso
- Laboratorio de Biología y Fisiología Celular "Dr. Francisco Bertini"- Instituto de Histología y Embriología - FCM, Universidad Nacional de Cuyo, Mendoza, Argentina; Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - M A Sosa
- Laboratorio de Biología y Fisiología Celular "Dr. Francisco Bertini"- Instituto de Histología y Embriología - FCM, Universidad Nacional de Cuyo, Mendoza, Argentina; Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - A M Seltzer
- Plataforma de Neurobiología- Instituto de Histología y Embriología (CONICET), Mendoza. Argentina.
| |
Collapse
|
4
|
Clathrin-nanoparticles deliver BDNF to hippocampus and enhance neurogenesis, synaptogenesis and cognition in HIV/neuroAIDS mouse model. Commun Biol 2022; 5:236. [PMID: 35301411 PMCID: PMC8931075 DOI: 10.1038/s42003-022-03177-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 02/17/2022] [Indexed: 01/02/2023] Open
Abstract
Brain derived neurotrophic factor (BDNF) promotes the growth, differentiation, maintenance and survival of neurons. These attributes make BDNF a potentially powerful therapeutic agent. However, its charge, instability in blood, and poor blood brain barrier (BBB) penetrability have impeded its development. Here, we show that engineered clathrin triskelia (CT) conjugated to BDNF (BDNF-CT) and delivered intranasally increased hippocampal BDNF concentrations 400-fold above that achieved previously with intranasal BDNF alone. We also show that BDNF-CT targeted Tropomyosin receptor kinase B (TrkB) and increased TrkB expression and downstream signaling in iTat mouse brains. Mice were induced to conditionally express neurotoxic HIV Transactivator-of-Transcription (Tat) protein that decreases BDNF. Down-regulation of BDNF is correlated with increased severity of HIV/neuroAIDS. BDNF-CT enhanced neurorestorative effects in the hippocampus including newborn cell proliferation and survival, granule cell neurogenesis, synaptogenesis and increased dendritic integrity. BDNF-CT exerted cognitive-enhancing effects by reducing Tat-induced learning and memory deficits. These results show that CT bionanoparticles efficiently deliver BDNF to the brain, making them potentially powerful tools in regenerative medicine.
Collapse
|
5
|
Gock N, Follett J, Rintoul GL, Beischlag TV, Lee FJ. Endosomal recycling and dopamine neurotransmission: Exploring the links between the retromer and Parkinson's disease. Synapse 2022; 76:e22224. [DOI: 10.1002/syn.22224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 12/17/2021] [Accepted: 01/23/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Nathan Gock
- Faculty of Health Sciences Simon Fraser University 8888 University Dr Burnaby BC V5A 1S6 Canada
- Centre for Cell Biology, Development, and Disease Simon Fraser University 8888 University Dr Burnaby BC V5A 1S6 Canada
| | - Jordan Follett
- Laboratory of Neurogenetics and Neuroscience Department of Neurology University of Florida 1149 Newell Dr Gainesville FL 32610‐0236 United States
| | - Gordon L Rintoul
- Department of Biological Sciences Simon Fraser University 8888 University Dr Burnaby BC V5A 1S6 Canada
- Centre for Cell Biology, Development, and Disease Simon Fraser University 8888 University Dr Burnaby BC V5A 1S6 Canada
| | - Timothy V Beischlag
- Faculty of Health Sciences Simon Fraser University 8888 University Dr Burnaby BC V5A 1S6 Canada
- Centre for Cell Biology, Development, and Disease Simon Fraser University 8888 University Dr Burnaby BC V5A 1S6 Canada
| | - Frank J.S. Lee
- Faculty of Health Sciences Simon Fraser University 8888 University Dr Burnaby BC V5A 1S6 Canada
- Centre for Cell Biology, Development, and Disease Simon Fraser University 8888 University Dr Burnaby BC V5A 1S6 Canada
| |
Collapse
|
6
|
López-Hernández T, Takenaka KI, Mori Y, Kongpracha P, Nagamori S, Haucke V, Takamori S. Clathrin-independent endocytic retrieval of SV proteins mediated by the clathrin adaptor AP-2 at mammalian central synapses. eLife 2022; 11:e71198. [PMID: 35014951 PMCID: PMC8752090 DOI: 10.7554/elife.71198] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 12/28/2021] [Indexed: 12/25/2022] Open
Abstract
Neurotransmission is based on the exocytic fusion of synaptic vesicles (SVs) followed by endocytic membrane retrieval and the reformation of SVs. Conflicting models have been proposed regarding the mechanisms of SV endocytosis, most notably clathrin/adaptor protein complex 2 (AP-2)-mediated endocytosis and clathrin-independent ultrafast endocytosis. Partitioning between these pathways has been suggested to be controlled by temperature and stimulus paradigm. We report on the comprehensive survey of six major SV proteins to show that SV endocytosis in mouse hippocampal neurons at physiological temperature occurs independent of clathrin while the endocytic retrieval of a subset of SV proteins including the vesicular transporters for glutamate and GABA depend on sorting by the clathrin adaptor AP-2. Our findings highlight a clathrin-independent role of the clathrin adaptor AP-2 in the endocytic retrieval of select SV cargos from the presynaptic cell surface and suggest a revised model for the endocytosis of SV membranes at mammalian central synapses.
Collapse
Affiliation(s)
| | - Koh-ichiro Takenaka
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha UniversityKyotoJapan
| | - Yasunori Mori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha UniversityKyotoJapan
| | - Pornparn Kongpracha
- Department of Laboratory Medicine, The Jikei University School of MedicineTokyoJapan
| | - Shushi Nagamori
- Department of Laboratory Medicine, The Jikei University School of MedicineTokyoJapan
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP)BerlinGermany
| | - Shigeo Takamori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha UniversityKyotoJapan
| |
Collapse
|
7
|
Release Mode Dynamically Regulates the RRP Refilling Mechanism at Individual Hippocampal Synapses. J Neurosci 2020; 40:8426-8437. [PMID: 32989096 DOI: 10.1523/jneurosci.3029-19.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 09/08/2020] [Accepted: 09/15/2020] [Indexed: 12/15/2022] Open
Abstract
Synaptic strength and reliability are determined by the number of vesicles released per action potential and the availability of release-competent vesicles in the readily releasable pool (RRP). Compared with release of a single vesicle (univesicular release), multivesicular release (MVR) would speed up RRP depletion, yet whether the RRP is refilled differently during the two different release modes has not been investigated. Here, we address this question by quantitative optical imaging with an axon-targeting glutamate sensor, iGluSnFRpre. We found that hippocampal synapses preferentially release multiple vesicles per action potential at high extracellular calcium or by paired-pulse stimulation. When MVR prevails, the RRP is recovered very rapidly with a time constant of 430 ms. This rapid recovery is mediated by dynamin-dependent endocytosis followed by direct reuse of retrieved vesicles. Furthermore, our simulation proved that the portion of retrieved vesicles that directly refill the RRP increases dramatically (>70%) in MVR compared with that in univesicular release (<10%). These results suggest that the contribution of rapid and direct recruitment of retrieved vesicle to the RRP changes dynamically with release mode at the level of individual synapses, which suggests a form of presynaptic homeostatic plasticity for reliable synaptic transmission during various synaptic activity.SIGNIFICANCE STATEMENT The number of vesicles released in response to an action potential and the number of release competent vesicles in the readily releasable pool (RRP) are the fundamental determinants of synaptic efficacy. Despite its functional advantages, releasing multiple vesicles, especially at small synapses, can deplete the RRP after a couple of action potentials. To prevent failure of synaptic transmission, the RRP should be refilled rapidly, yet whether the RRP replenishment process is regulated by the release mode has not been investigated. Here, using quantitative optical glutamate imaging and simulation, we demonstrate that the contribution of the fast refilling mechanism changes with release mode at the level of individual synapses, suggesting a rapid form of presynaptic homeostatic plasticity during various synaptic activity.
Collapse
|
8
|
Guzman GA, Guzman RE, Jordan N, Hidalgo P. A Tripartite Interaction Among the Calcium Channel α 1- and β-Subunits and F-Actin Increases the Readily Releasable Pool of Vesicles and Its Recovery After Depletion. Front Cell Neurosci 2019; 13:125. [PMID: 31130843 PMCID: PMC6509170 DOI: 10.3389/fncel.2019.00125] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 03/13/2019] [Indexed: 11/13/2022] Open
Abstract
Neurotransmitter release is initiated by the influx of Ca2+via voltage-gated calcium channels. The accessory β-subunit (CaVβ) of these channels shapes synaptic transmission by associating with the pore-forming subunit (CaVα1) and up-regulating presynaptic calcium currents. Besides CaVα1, CaVβ interacts with several partners including actin filaments (F-actin). These filaments are known to associate with synaptic vesicles (SVs) at the presynaptic terminals and support their translocation within different pools, but the role of CaVβ/F-actin association on synaptic transmission has not yet been explored. We here study how CaVβ4, the major calcium channel β isoform in mamalian brain, modifies synaptic transmission in concert with F-actin in cultured hippocampal neurons. We analyzed the effect of exogenous CaVβ4 before and after pharmacological disruption of the actin cytoskeleton and dissected calcium channel-dependent and -independent functions by comparing the effects of the wild-type subunit with the one bearing a double mutation that impairs binding to CaVα1. We found that exogenously expressed wild-type CaVβ4 enhances spontaneous and depolarization-evoked excitatory postsynaptic currents (EPSCs) without altering synaptogenesis. CaVβ4 increases the size of the readily releasable pool (RRP) of SVs at resting conditions and accelerates their recovery after depletion. The enhanced neurotransmitter release induced by CaVβ4 is abolished upon disruption of the actin cytoskeleton. The CaVα1 association-deficient CaVβ4 mutant associates with actin filaments, but neither alters postsynaptic responses nor the time course of the RRP recovery. Furthermore, this mutant protein preserves the ability to increase the RRP size. These results indicate that the interplay between CaVβ4 and F-actin also support the recruitment of SVs to the RRP in a CaVα1-independent manner. Our studies show an emerging role of CaVβ in determining SV maturation toward the priming state and its replenishment after release. We envision that this subunit plays a role in coupling exocytosis to endocytosis during the vesicle cycle.
Collapse
Affiliation(s)
- Gustavo A Guzman
- Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, Jülich, Germany
| | - Raul E Guzman
- Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, Jülich, Germany
| | - Nadine Jordan
- Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, Jülich, Germany
| | - Patricia Hidalgo
- Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, Jülich, Germany.,Institute of Biochemistry, Heinrich-Heine University, Düsseldorf, Germany
| |
Collapse
|
9
|
Pan PY, Zhu Y, Shen Y, Yue Z. Crosstalk between presynaptic trafficking and autophagy in Parkinson's disease. Neurobiol Dis 2019; 122:64-71. [PMID: 29723605 PMCID: PMC10942671 DOI: 10.1016/j.nbd.2018.04.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 04/20/2018] [Accepted: 04/28/2018] [Indexed: 01/22/2023] Open
Abstract
Parkinson's disease (PD) is a debilitating neurodegenerative disorder that profoundly affects one's motor functions. The disease is characterized pathologically by denervation of dopaminergic (DAergic) nigrostriatal terminal and degeneration of DAergic neurons in the substantia nigra par compacta (SNpc); however, the precise molecular mechanism underlying disease pathogenesis remains poorly understood. Animal studies in both toxin-induced and genetic PD models suggest that presynaptic impairments may underlie the early stage of DA depletion and neurodegeneration (reviewed in Schirinzi, T., et al. 2016). Supporting this notion, human genetic studies and genomic analysis have identified an increasing number of PD risk variants that are associated with synaptic vesicle (SV) trafficking, regulation of synaptic function and autophagy/lysosomal system (Chang, D., et al. 2017, reviewed in Trinh, J. & Farrer, M. 2013; Singleton, A.B., et al. 2013). Although the precise mechanism for autophagy regulation in neurons is currently unclear, many studies demonstrate that autophagosomes form at the presynaptic terminal (Maday, S. & Holzbaur, E.L. 2014; Vanhauwaert, R., et al. 2017; reviewed in Yue, Z. 2007). Growing evidence has revealed overlapping genes involved in both SV recycling and autophagy, suggesting that the two membrane trafficking processes are inter-connected. Here we will review emergent evidence linking SV endocytic genes and autophagy genes at the presynaptic terminal. We will discuss their potential relevance to PD pathogenesis.
Collapse
Affiliation(s)
- Ping-Yue Pan
- Department of Neurology, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, Hess Research Center 9th Floor, New York, NY 10029, USA
| | - Yingbo Zhu
- Department of Psychiatry, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, China
| | - Yuan Shen
- Department of Psychiatry, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, China
| | - Zhenyu Yue
- Department of Neurology, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, Hess Research Center 9th Floor, New York, NY 10029, USA.
| |
Collapse
|
10
|
Li Z, Wang M, Yao X, Li H, Li S, Liu L, Yu D, Li X, Fang J, Huang C. Development of novel anti-CD19 antibody-drug conjugates for B-cell lymphoma treatment. Int Immunopharmacol 2018; 62:299-308. [PMID: 30048860 DOI: 10.1016/j.intimp.2018.06.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 06/08/2018] [Accepted: 06/25/2018] [Indexed: 02/07/2023]
Abstract
B-cell lymphoma remains one of the most refractory tumors, and as such the development of novel treatment approaches, such as antibody-drug conjugates (ADCs), is required. To improve the stability and homogeneity of the ADCs, a humanized anti-CD19 monoclonal antibody (RC58) was developed in the present study. RC58 was based on the CD19 antigen as a potential molecular target of human B-cell lymphomas. RC58 has high CD19-binding affinity and can be internalized in CD19-positive cells through endocytosis. Furthermore, three types of RC58-based ADCs (ADC-1, ADC-2, and ADC-3) were generated using three kinds of Maleimide-PEG-based linkers with two different cytotoxins. The anti-tumor activities of the ADCs were confirmed by in vitro and in vivo experiments. The stability of the ADCs was also evaluated by incubation in human plasma for 10 days. In vitro experiments showed that the three ADCs had distinct inhibitory effects on several B-lymphoma cell lines. Meanwhile, a close correlation between efficacy and drug concentration was found in a nude mouse xenograft model of human B-cell lymphoma, after treatment with RC58-based ADCs. Our results suggest that ADC-1, with high efficiency, could be used as a potential therapeutic agent for human B-cell malignancies.
Collapse
Affiliation(s)
| | - Mingxue Wang
- Mabplex International Ltd., Yantai 264006, Shandong, China
| | - Xuejing Yao
- RemeGen, Ltd., Yantai 264006, Shandong, China
| | - Huanzhao Li
- Mabplex International Ltd., Yantai 264006, Shandong, China
| | - Shenjun Li
- RemeGen, Ltd., Yantai 264006, Shandong, China
| | - Lina Liu
- Mabplex International Ltd., Yantai 264006, Shandong, China
| | - Deling Yu
- Mabplex International Ltd., Yantai 264006, Shandong, China
| | - Xue Li
- Mabplex International Ltd., Yantai 264006, Shandong, China
| | - Jianmin Fang
- RemeGen, Ltd., Yantai 264006, Shandong, China; Mabplex International Ltd., Yantai 264006, Shandong, China; School of Life Science and Technology, Tongji University, Shanghai 200092, China
| | | |
Collapse
|
11
|
Gan Q, Watanabe S. Synaptic Vesicle Endocytosis in Different Model Systems. Front Cell Neurosci 2018; 12:171. [PMID: 30002619 PMCID: PMC6031744 DOI: 10.3389/fncel.2018.00171] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Accepted: 06/01/2018] [Indexed: 11/13/2022] Open
Abstract
Neurotransmission in complex animals depends on a choir of functionally distinct synapses releasing neurotransmitters in a highly coordinated manner. During synaptic signaling, vesicles fuse with the plasma membrane to release their contents. The rate of vesicle fusion is high and can exceed the rate at which synaptic vesicles can be re-supplied by distant sources. Thus, local compensatory endocytosis is needed to replenish the synaptic vesicle pools. Over the last four decades, various experimental methods and model systems have been used to study the cellular and molecular mechanisms underlying synaptic vesicle cycle. Clathrin-mediated endocytosis is thought to be the predominant mechanism for synaptic vesicle recycling. However, recent studies suggest significant contribution from other modes of endocytosis, including fast compensatory endocytosis, activity-dependent bulk endocytosis, ultrafast endocytosis, as well as kiss-and-run. Currently, it is not clear whether a universal model of vesicle recycling exist for all types of synapses. It is possible that each synapse type employs a particular mode of endocytosis. Alternatively, multiple modes of endocytosis operate at the same synapse, and the synapse toggles between different modes depending on its activity level. Here we compile review and research articles based on well-characterized model systems: frog neuromuscular junctions, C. elegans neuromuscular junctions, Drosophila neuromuscular junctions, lamprey reticulospinal giant axons, goldfish retinal ribbon synapses, the calyx of Held, and rodent hippocampal synapses. We will compare these systems in terms of their known modes and kinetics of synaptic vesicle endocytosis, as well as the underlying molecular machineries. We will also provide the future development of this field.
Collapse
Affiliation(s)
- Quan Gan
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Shigeki Watanabe
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| |
Collapse
|
12
|
Hempel CM, Werley CA, Dempsey GT, Gerber DJ. Targeting neuronal function for CNS drug discovery. DRUG DISCOVERY TODAY. TECHNOLOGIES 2017. [PMID: 28647082 DOI: 10.1016/j.ddtec.2017.03.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
There is a pressing need for new and more effective treatments for central nervous system (CNS) disorders. A large body of evidence now suggests that alterations in synaptic transmission and neuronal excitability represent underlying factors for many neurological and psychiatric diseases. However, it has been challenging to target these complex functional domains for therapeutic discovery using traditional neuronal assay methods. Here we review advances in neuronal screening technologies and cellular model systems that enable phenotypic screening of neuronal function as a basis for novel CNS drug discovery approaches.
Collapse
Affiliation(s)
- Chris M Hempel
- Q-State Biosciences, 179 Sidney Street, Cambridge, MA 02139, USA
| | | | - Graham T Dempsey
- Q-State Biosciences, 179 Sidney Street, Cambridge, MA 02139, USA
| | - David J Gerber
- Q-State Biosciences, 179 Sidney Street, Cambridge, MA 02139, USA.
| |
Collapse
|
13
|
Luo C, Chen S, Xu N, Sai WB, Zhao W, Li YC, Hu XJ, Tian H, Gao XD, Yao WB. Establishment of a fluorescence-based method to evaluate endocytosis of desialylated glycoproteins in vitro. Biomed Pharmacother 2017; 88:87-94. [PMID: 28095357 DOI: 10.1016/j.biopha.2016.12.085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 12/17/2016] [Accepted: 12/20/2016] [Indexed: 01/12/2023] Open
Abstract
Insufficient sialylation can result in rapid clearance of therapeutic glycoproteins by intracellular degradation, which is mainly mediated by asialoglycoprotein receptors (ASGPRs) on hepatic cells. In contrast, for glycoproteins, a long half-life is often related to high level of terminal sialic acid. These could be extremely important for insufficient sialylated biomedicines in clinic, and development of therapeutic glycoproteins in laboratory. However, how the desialylated glycoproteins are removed and how to evaluate the ASGPRs mediated endocytosis in vitro needs further investigate. Herein we described an integrative characterization of ASGPRs in vitro to elucidate its endocytosis properties. The endocytosis was determined by a fluorescence-based quantization method. The results showed that the ASGPRs could bind to poorly sialylated glycoproteins including asialofetuin and low sialylated recombinant Factor VIIa with a relatively higher ASGPRs binding affinity, and induce a more rapid endocytosis in vitro. Moreover, the mechanism under the internalization of ASGPRs was also investigated, which was found to depend on clathrin and caveolin. Utilizing the relative fluorescence quantification can be suitable for measurement of insufficient sialylated glycoprotein endocytosis and quality control of therapeutic glycoproteins, which could be useful for the understanding of the development of therapeutic glycoproteins.
Collapse
Affiliation(s)
- Cheng Luo
- Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing, 210009 China
| | - Song Chen
- Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing, 210009 China
| | - Na Xu
- Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing, 210009 China
| | - Wen Bo Sai
- Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing, 210009 China
| | - Wei Zhao
- Jiangsu Chia Tai Tianqing Pharmaceutical Co., Ltd., Nanjing, 210023 China
| | - Ying Chun Li
- Jiangsu Chia Tai Tianqing Pharmaceutical Co., Ltd., Nanjing, 210023 China
| | - Xiao Jing Hu
- Jiangsu Chia Tai Tianqing Pharmaceutical Co., Ltd., Nanjing, 210023 China
| | - Hong Tian
- Jiangsu Chia Tai Tianqing Pharmaceutical Co., Ltd., Nanjing, 210023 China
| | - Xiang Dong Gao
- Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing, 210009 China.
| | - Wen Bing Yao
- Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing, 210009 China.
| |
Collapse
|
14
|
σ2-Adaptin Facilitates Basal Synaptic Transmission and Is Required for Regenerating Endo-Exo Cycling Pool Under High-Frequency Nerve Stimulation in Drosophila. Genetics 2016; 203:369-85. [PMID: 26920756 DOI: 10.1534/genetics.115.183863] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 02/21/2016] [Indexed: 11/18/2022] Open
Abstract
The functional requirement of adapter protein 2 (AP2) complex in synaptic membrane retrieval by clathrin-mediated endocytosis is not fully understood. Here we isolated and functionally characterized a mutation that dramatically altered synaptic development. Based on the aberrant neuromuscular junction (NMJ) synapse, we named this mutation angur (a Hindi word meaning "grapes"). Loss-of-function alleles of angur show more than twofold overgrowth in bouton numbers and a dramatic decrease in bouton size. We mapped the angur mutation to σ2-adaptin, the smallest subunit of the AP2 complex. Reducing the neuronal level of any of the subunits of the AP2 complex or disrupting AP2 complex assembly in neurons phenocopied the σ2-adaptin mutation. Genetic perturbation of σ2-adaptin in neurons leads to a reversible temperature-sensitive paralysis at 38°. Electrophysiological analysis of the mutants revealed reduced evoked junction potentials and quantal content. Interestingly, high-frequency nerve stimulation caused prolonged synaptic fatigue at the NMJs. The synaptic levels of subunits of the AP2 complex and clathrin, but not other endocytic proteins, were reduced in the mutants. Moreover, bone morphogenetic protein (BMP)/transforming growth factor β (TGFβ) signaling was altered in these mutants and was restored by normalizing σ2-adaptin in neurons. Thus, our data suggest that (1) while σ2-adaptin facilitates synaptic vesicle (SV) recycling for basal synaptic transmission, its activity is also required for regenerating SVs during high-frequency nerve stimulation, and (2) σ2-adaptin regulates NMJ morphology by attenuating TGFβ signaling.
Collapse
|
15
|
Wang YC, Fang F, Wu YK, Ai XL, Lan T, Liang RC, Zhang Y, Trishul NM, He M, You C, Yu C, Tan H. Waterborne biodegradable polyurethane 3-dimensional porous scaffold for rat cerebral tissue regeneration. RSC Adv 2016. [DOI: 10.1039/c5ra20181k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
It was demonstrated for the first time that WBPU 3D scaffold had axonal and synaptic regeneration abilities in rat brains.
Collapse
|
16
|
Abstract
Synaptic vesicles release their vesicular contents to the extracellular space by Ca(2+)-triggered exocytosis. The Ca(2+)-triggered exocytotic process is regulated by synaptotagmin (Syt), a vesicular Ca(2+)-binding C2 domain protein. Synaptotagmin 1 (Syt1), the most studied major isoform among 16 Syt isoforms, mediates Ca(2+)-triggered synaptic vesicle exocytosis by interacting with the target membranes and SNARE/complexin complex. In synapses of the central nervous system, synaptobrevin 2, a major vesicular SNARE protein, forms a ternary SNARE complex with the plasma membrane SNARE proteins, syntaxin 1 and SNAP25. The affinities of Ca(2+)-dependent interactions between Syt1 and its targets (i.e., SNARE complexes and membranes) are well correlated with the efficacies of the corresponding exocytotic processes. Therefore, different SNARE protein isoforms and membrane lipids, which interact with Syt1 with various affinities, are capable of regulating the efficacy of Syt1-mediated exocytosis. Otoferlin, another type of vesicular C2 domain protein that binds to the membrane in a Ca(2+)-dependent manner, is also involved in the Ca(2+)-triggered synaptic vesicle exocytosis in auditory hair cells. However, the functions of otoferlin in the exocytotic process are not well understood. In addition, at least five different types of synaptic vesicle proteins such as synaptic vesicle protein 2, cysteine string protein α, rab3, synapsin, and a group of proteins containing four transmembrane regions, which includes synaptophysin, synaptogyrin, and secretory carrier membrane protein, are involved in modulating the exocytotic process by regulating the formation and trafficking of synaptic vesicles.
Collapse
Affiliation(s)
- Ok-Ho Shin
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas
| |
Collapse
|
17
|
Pelassa I, Zhao C, Pasche M, Odermatt B, Lagnado L. Synaptic vesicles are "primed" for fast clathrin-mediated endocytosis at the ribbon synapse. Front Mol Neurosci 2014; 7:91. [PMID: 25520613 PMCID: PMC4248811 DOI: 10.3389/fnmol.2014.00091] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 11/03/2014] [Indexed: 11/13/2022] Open
Abstract
Retrieval of synaptic vesicles can occur 1-10 s after fusion, but the role of clathrin during this process has been unclear because the classical mode of clathrin-mediated endocytosis (CME) is an order of magnitude slower, as during retrieval of surface receptors. Classical CME is thought to be rate-limited by the recruitment of clathrin, which raises the question: how is clathrin recruited during synaptic vesicle recycling? To investigate this question we applied total internal reflection fluorescence microscopy (TIRFM) to the synaptic terminal of retinal bipolar cells expressing fluorescent constructs of clathrin light-chain A. Upon calcium influx we observed a fast accumulation of clathrin within 100 ms at the periphery of the active zone. The subsequent loss of clathrin from these regions reflected endocytosis because the application of a potent clathrin inhibitor Pitstop2 dramatically slowed down this phase by ~3 fold. These results indicate that clathrin-dependent retrieval of synaptic vesicles is unusually fast, most probably because of a "priming" step involving a state of association of clathrin with the docked vesicle and with the endosomes and cisternae surrounding the ribbons. Fluorescence correlation spectroscopy (FCS) and fluorescence recovery after photobleaching (FRAP) showed that the majority of clathrin is moving with the same kinetics as synaptic vesicle proteins. Together, these results indicate that the fast endocytic mechanism operating to retrieve synaptic vesicles differs substantially from the classical mode of CME operating via formation of a coated pit.
Collapse
Affiliation(s)
| | | | | | | | - Leon Lagnado
- Medical Research Council Laboratory of Molecular Biology, Neurobiology DivisionCambridge, UK
| |
Collapse
|
18
|
Moshkanbaryans L, Chan LS, Graham ME. The Biochemical Properties and Functions of CALM and AP180 in Clathrin Mediated Endocytosis. MEMBRANES 2014; 4:388-413. [PMID: 25090048 PMCID: PMC4194041 DOI: 10.3390/membranes4030388] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 07/03/2014] [Accepted: 07/22/2014] [Indexed: 01/26/2023]
Abstract
Clathrin-mediated endocytosis (CME) is a fundamental process for the regulated internalization of transmembrane cargo and ligands via the formation of vesicles using a clathrin coat. A vesicle coat is initially created at the plasma membrane by clathrin assembly into a lattice, while a specific cargo sorting process selects and concentrates proteins for inclusion in the new vesicle. Vesicles formed via CME traffic to different parts of the cell and fuse with target membranes to deliver cargo. Both clathrin assembly and cargo sorting functions are features of the two gene family consisting of assembly protein 180 kDa (AP180) and clathrin assembly lymphoid myeloid leukemia protein (CALM). In this review, we compare the primary structure and domain organization of CALM and AP180 and relate these properties to known functions and roles in CME and disease.
Collapse
Affiliation(s)
- Lia Moshkanbaryans
- Children's Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead, NSW 2145, Australia.
| | - Ling-Shan Chan
- Children's Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead, NSW 2145, Australia.
| | - Mark E Graham
- Children's Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead, NSW 2145, Australia.
| |
Collapse
|
19
|
New perspectives on using brain imaging to study CNS stimulants. Neuropharmacology 2014; 87:104-14. [PMID: 25080072 DOI: 10.1016/j.neuropharm.2014.07.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Revised: 06/26/2014] [Accepted: 07/07/2014] [Indexed: 11/23/2022]
Abstract
While the recent application of brain imaging to study CNS stimulants has offered new insights into the fundamental factors that contribute to their use and abuse, many gaps remain. Brain circuits that mediate pleasure, dependence, craving and relapse are anatomically, neurophysiologically and neurochemically distinct from one another, which has guided the search for correlates of stimulant-seeking and taking behavior. However, unlike other drugs of abuse, metrics for tolerance and physical dependence on stimulants are not obvious. The dopamine theory of stimulant abuse does not sufficiently explain this disorder as serotonergic, GABAergic and glutamagergic circuits are clearly involved in stimulant pharmacology and so tracking the source of the "addictive" processes must adopt a more multimodal, multidisciplinary approach. To this end, both anatomical and functional magnetic resonance imaging (MRI), MR spectroscopy (MRS) and positron emission tomography (PET) are complementary and have equally contributed to our understanding of how stimulants affect the brain and behavior. New vistas in this area include nanotechnology approaches to deliver small molecules to receptors and use MRI to resolve receptor dynamics. Anatomical and blood flow imaging has yielded data showing that cognitive enhancers might be useful adjuncts in treating CNS stimulant dependence, while MRS has opened opportunities to examine the brain's readiness to accept treatment as GABA tone normalizes after detoxification. A desired outcome of the above approaches is being able to offer evidence-based rationales for treatment approaches that can be implemented in a more broad geographic area, where access to brain imaging facilities may be limited. This article is part of the Special Issue entitled 'CNS Stimulants'.
Collapse
|
20
|
Fewou SN, Plomp JJ, Willison HJ. The pre-synaptic motor nerve terminal as a site for antibody-mediated neurotoxicity in autoimmune neuropathies and synaptopathies. J Anat 2013; 224:36-44. [PMID: 23937354 DOI: 10.1111/joa.12088] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2013] [Indexed: 12/20/2022] Open
Abstract
The pre-synaptic motor nerve terminal is a highly complex and dynamic compartment within the lower motor neuron responsible for converting electrical signals into secreted chemicals. This self-renewing process of synaptic transmission is accomplished by the calcium-triggered fusion of neurotransmitter-containing vesicles with the plasma membrane and the subsequent retrieval and recycling of vesicle components. Besides this conventional physiological role, the highly active process of vesicle fusion and re-uptake into endosomal sorting pathways acts as a conduit for entry of a range of substances into the intracellular compartment of the motor nerve terminal. Whilst this entry portal sub-serves many vital physiological processes, such as those mediated by neurotrophin trafficking, there is also the potential for substantial pathological consequences resulting from uptake of noxious agents, including autoantibodies, viruses and toxins. These may act locally to induce disease within the nerve terminal, or traffic beyond to the motor neuron cell body and central nervous system to exert their pathological effects. This review focuses on the recent evidence that the ganglioside-rich pre-synaptic membrane acts as a binding site for potentially neurotoxic serum autoantibodies that are present in human autoimmune motor neuropathies. Autoantibodies that bind surface antigens induce membrane lytic effects, whereas their uptake attenuates local injury and transfers any potential pathological consequences to the intracellular compartment. Herein the thesis is explored that a balance exists between local injury at the exofacial leaflet of the pre-synaptic membrane and antibody uptake, which dictates the overall level and site of motor nerve injury in this group of disorders.
Collapse
Affiliation(s)
- Simon N Fewou
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | | | | |
Collapse
|
21
|
Zakharov AV, Petrov AM, Kotov NV, Zefirov AL. Experimental and modeling investigation of the mechanism of synaptic vesicles recycling. Biophysics (Nagoya-shi) 2012. [DOI: 10.1134/s0006350912040203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
|
22
|
Vitaliano GD, Vitaliano F, Rios JD, Renshaw PF, Teicher MH. New clathrin-based nanoplatforms for magnetic resonance imaging. PLoS One 2012; 7:e35821. [PMID: 22563470 PMCID: PMC3341379 DOI: 10.1371/journal.pone.0035821] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Accepted: 03/26/2012] [Indexed: 12/31/2022] Open
Abstract
Background Magnetic Resonance Imaging (MRI) has high spatial resolution, but low sensitivity for visualization of molecular targets in the central nervous system (CNS). Our goal was to develop a new MRI method with the potential for non-invasive molecular brain imaging. We herein introduce new bio-nanotechnology approaches for designing CNS contrast media based on the ubiquitous clathrin cell protein. Methodology/Principal Findings The first approach utilizes three-legged clathrin triskelia modified to carry 81 gadolinium chelates. The second approach uses clathrin cages self-assembled from triskelia and designed to carry 432 gadolinium chelates. Clathrin triskelia and cages were characterized by size, structure, protein concentration, and chelate and gadolinium contents. Relaxivity was evaluated at 0.47 T. A series of studies were conducted to ascertain whether fluorescent-tagged clathrin nanoplatforms could cross the blood brain barriers (BBB) unaided following intranasal, intravenous, and intraperitoneal routes of administration. Clathrin nanoparticles can be constituted as triskelia (18.5 nm in size), and as cages assembled from them (55 nm). The mean chelate: clathrin heavy chain molar ratio was 27.04±4.8: 1 for triskelia, and 4.2±1.04: 1 for cages. Triskelia had ionic relaxivity of 16 mM−1s−1, and molecular relaxivity of 1,166 mM−1s−1, while cages had ionic relaxivity of 81 mM−1s−1 and molecular relaxivity of 31,512 mM−1s−1. Thus, cages exhibited 20 times higher ionic relaxivity and 8,000-fold greater molecular relaxivity than gadopentetate dimeglumine. Clathrin nanoplatforms modified with fluorescent tags were able to cross or bypass the BBB without enhancements following intravenous, intraperitoneal and intranasal administration in rats. Conclusions/Significance Use of clathrin triskelia and cages as carriers of CNS contrast media represents a new approach. This new biocompatible protein-based nanotechnology demonstrated suitable physicochemical properties to warrant further in vivo imaging and drug delivery studies. Significantly, both nanotransporters crossed and/or bypassed the BBB without enhancers. Thus, clathrin nanoplatforms could be an appealing alternative to existing CNS bio-nanotechnologies.
Collapse
Affiliation(s)
- Gordana D Vitaliano
- Laboratory of Developmental Psychopharmacology, Brain Imaging Center, Department of Psychiatry, Harvard Medical School, McLean Hospital, Belmont, Massachusetts, United States of America.
| | | | | | | | | |
Collapse
|
23
|
Pineda Rodó A, Váchová L, Palková Z. In vivo determination of organellar pH using a universal wavelength-based confocal microscopy approach. PLoS One 2012; 7:e33229. [PMID: 22470445 PMCID: PMC3310042 DOI: 10.1371/journal.pone.0033229] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Accepted: 02/12/2012] [Indexed: 11/19/2022] Open
Abstract
Many essential cellular processes are affected by transmembrane H(+) gradients and intracellular pH (pHi). The research of such metabolic events calls for a non-invasive method to monitor pHi within individual subcellular compartments. We present a novel confocal microscopy approach for the determination of organellar pHi in living cells expressing pH-dependent ratiometric fluorescent proteins. Unlike conventional intensity-based fluorometry, our method relies on emission wavelength scans at single-organelle resolution to produce wavelength-based pH estimates both accurate and robust to low-signal artifacts. Analyses of Ato1p-pHluorin and Ato1p-mCherry yeast cells revealed previously unreported wavelength shifts in pHluorin emission which, together with ratiometric mCherry, allowed for high-precision quantification of actual physiological pH values and evidenced dynamic pHi changes throughout the different stages of yeast colony development. Additionally, comparative pH quantification of Ato1p-pHluorin and Met17p-pHluorin cells implied the existence of a significant pHi gradient between peripheral and internal cytoplasm of cells from colonies occurring in the ammonia-producing alkali developmental phase. Results represent a step forward in the study of pHi regulation and subcellular metabolic functions beyond the scope of this study.
Collapse
Affiliation(s)
- Albert Pineda Rodó
- Department of Genetics and Microbiology, Charles University, Prague, Czech Republic
| | - Libuše Váchová
- Department of Genetics and Microbiology, Charles University, Prague, Czech Republic
- Institute of Microbiology, Academy of Sciences, Prague, Czech Republic
| | - Zdena Palková
- Department of Genetics and Microbiology, Charles University, Prague, Czech Republic
| |
Collapse
|
24
|
Borgonovo J, Capella P, Seltzer A, Sosa MA. Expression of coat proteins changes during postnatal development in selected areas of the rat brain. Int J Dev Neurosci 2012; 30:333-41. [PMID: 22306374 DOI: 10.1016/j.ijdevneu.2012.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Revised: 01/03/2012] [Accepted: 01/17/2012] [Indexed: 11/25/2022] Open
Abstract
It is well known that clathrin-mediated endocytosis is crucial for the normal functioning and integrity of neurons in the central nervous system. In this study we attempted to correlate the expression of coat proteins with development in different areas of rat brain. By Western blot, we studied the expression of AP-2, GGA1 and GGA2 in striatum, cerebellum, brain stem, cerebral cortex and hippocampus of newborn rats and during post-natal development; 5, 15, 30, 60, 90 or 150 days after birth. We observed that the expression of the α2 subunit of AP-2 increased substantially between the 15th and 30th day after birth in all areas studied, excepting the cerebellum and cortex. On the other hand, the expression of the α1 subunit does not change significantly during the development in any of the areas under study. We also noted that the expression of the μ2 subunit did not follow the pattern of α2 during development. In general terms, the expression of GGA1 and GGA2 followed a similar pattern to that of AP-2, although these proteins increased significantly in the cerebral cortex from the 15th day after birth. Moreover, presenilin-1, a protein associated with aging and neurodegeneration, shows an expression pattern similar to coat proteins in the striatum and cortex. These results suggest that proteins that conform the intracellular transport machinery in the brain cells seems to accompany development, according to the maturation of the different brain areas.
Collapse
Affiliation(s)
- Janina Borgonovo
- Laboratorio de Biología y Fisiología Celular "Dr. Francisco Bertini", Instituto de Histología y Embriología, FCM, Universidad Nacional de Cuyo, Mendoza, Argentina
| | | | | | | |
Collapse
|
25
|
Toxicogenomic and phenotypic analyses of bisphenol-A early-life exposure toxicity in zebrafish. PLoS One 2011; 6:e28273. [PMID: 22194820 PMCID: PMC3237442 DOI: 10.1371/journal.pone.0028273] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 11/04/2011] [Indexed: 11/19/2022] Open
Abstract
Bisphenol-A is an important environmental contaminant due to the increased early-life exposure that may pose significant health-risks to various organisms including humans. This study aimed to use zebrafish as a toxicogenomic model to capture transcriptomic and phenotypic changes for inference of signaling pathways, biological processes, physiological systems and identify potential biomarker genes that are affected by early-life exposure to bisphenol-A. Phenotypic analysis using wild-type zebrafish larvae revealed BPA early-life exposure toxicity caused cardiac edema, cranio-facial abnormality, failure of swimbladder inflation and poor tactile response. Fluorescent imaging analysis using three transgenic lines revealed suppressed neuron branching from the spinal cord, abnormal development of neuromast cells, and suppressed vascularization in the abdominal region. Using knowledge-based data mining algorithms, transcriptome analysis suggests that several signaling pathways involving ephrin receptor, clathrin-mediated endocytosis, synaptic long-term potentiation, axonal guidance, vascular endothelial growth factor, integrin and tight junction were deregulated. Physiological systems with related disorders associated with the nervous, cardiovascular, skeletal-muscular, blood and reproductive systems were implicated, hence corroborated with the phenotypic analysis. Further analysis identified a common set of BPA-targeted genes and revealed a plausible mechanism involving disruption of endocrine-regulated genes and processes in known susceptible tissue-organs. The expression of 28 genes were validated in a separate experiment using quantitative real-time PCR and 6 genes, ncl1, apoeb, mdm1, mycl1b, sp4, U1SNRNPBP homolog, were found to be sensitive and robust biomarkers for BPA early-life exposure toxicity. The susceptibility of sp4 to BPA perturbation suggests its role in altering brain development, function and subsequently behavior observed in laboratory animals exposed to BPA during early life, which is a health-risk concern of early life exposure in humans. The present study further established zebrafish as a model for toxicogenomic inference of early-life chemical exposure toxicity.
Collapse
|
26
|
Rao Y, Haucke V. Membrane shaping by the Bin/amphiphysin/Rvs (BAR) domain protein superfamily. Cell Mol Life Sci 2011; 68:3983-93. [PMID: 21769645 PMCID: PMC11114942 DOI: 10.1007/s00018-011-0768-5] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 06/27/2011] [Accepted: 06/30/2011] [Indexed: 01/27/2023]
Abstract
BAR domain superfamily proteins have emerged as central regulators of dynamic membrane remodeling, thereby playing important roles in a wide variety of cellular processes, such as organelle biogenesis, cell division, cell migration, secretion, and endocytosis. Here, we review the mechanistic and structural basis for the membrane curvature-sensing and deforming properties of BAR domain superfamily proteins. Moreover, we summarize the present state of knowledge with respect to their regulation by autoinhibitory mechanisms or posttranslational modifications, and their interactions with other proteins, in particular with GTPases, and with membrane lipids. We postulate that BAR superfamily proteins act as membrane-deforming scaffolds that spatiotemporally orchestrate membrane remodeling.
Collapse
Affiliation(s)
- Yijian Rao
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
- Present Address: Max Planck Institute for Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Volker Haucke
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Berlin, Charitéplatz 1, 10117 Berlin, Germany
- Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Straße 10, 13125 Berlin, Germany
| |
Collapse
|
27
|
Powell AD, Gill KK, Saintot PP, Jiruska P, Chelly J, Billuart P, Jefferys JGR. Rapid reversal of impaired inhibitory and excitatory transmission but not spine dysgenesis in a mouse model of mental retardation. J Physiol 2011; 590:763-76. [PMID: 22124149 DOI: 10.1113/jphysiol.2011.219907] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Intellectual disability affects 2-3% of the population: those due to mutations of the X-chromosome are a major cause of moderate to severe cases (1.8/1000 males). Established theories ascribe the cellular aetiology of intellectual disability to malformations of dendritic spines. Recent work has identified changes in synaptic physiology in some experimental models. Here, we investigated the pathophysiology of a mouse model of intellectual disability using electrophysiological recordings combined with confocal imaging of dentate gyrus granule neurons. Lack of oligophrenin-1 resulted in reductions in dendritic tree complexity and mature dendritic spine density and in evoked and spontaneous EPSCs and IPSCs. In the case of inhibitory transmission, the physiological change was associated with a reduction in the readily releasable pool and vesicle recycling which impaired the efficiency of inhibitory synaptic transmission. Acute inhibition of the downstream signalling pathway of oligophrenin-1 fully reversed the functional changes in synaptic transmission but not the dendritic abnormalities. The impaired inhibitory (as well as excitatory) synaptic transmission at frequencies associated with cognitive function suggests a cellular mechanism for the intellectual disability, because cortical oscillations associated with cognition normally depend on inhibitory neurons firing on every cycle.
Collapse
Affiliation(s)
- Andrew D Powell
- School of Clinical and Experimental Medicine (Neuronal Networks Group), College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | | | | | | | | | | | | |
Collapse
|
28
|
Effects of transport inhibitors on the cellular uptake of carboxylated polystyrene nanoparticles in different cell lines. PLoS One 2011; 6:e24438. [PMID: 21949717 PMCID: PMC3176276 DOI: 10.1371/journal.pone.0024438] [Citation(s) in RCA: 308] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 08/10/2011] [Indexed: 12/31/2022] Open
Abstract
Nanotechnology is expected to play a vital role in the rapidly developing field of nanomedicine, creating innovative solutions and therapies for currently untreatable diseases, and providing new tools for various biomedical applications, such as drug delivery and gene therapy. In order to optimize the efficacy of nanoparticle (NP) delivery to cells, it is necessary to understand the mechanisms by which NPs are internalized by cells, as this will likely determine their ultimate sub-cellular fate and localisation. Here we have used pharmacological inhibitors of some of the major endocytic pathways to investigate nanoparticle uptake mechanisms in a range of representative human cell lines, including HeLa (cervical cancer), A549 (lung carcinoma) and 1321N1 (brain astrocytoma). Chlorpromazine and genistein were used to inhibit clathrin and caveolin mediated endocytosis, respectively. Cytochalasin A and nocodazole were used to inhibit, respectively, the polymerisation of actin and microtubule cytoskeleton. Uptake experiments were performed systematically across the different cell lines, using carboxylated polystyrene NPs of 40 nm and 200 nm diameters, as model NPs of sizes comparable to typical endocytic cargoes. The results clearly indicated that, in all cases and cell types, NPs entered cells via active energy dependent processes. NP uptake in HeLa and 1321N1 cells was strongly affected by actin depolymerisation, while A549 cells showed a stronger inhibition of NP uptake (in comparison to the other cell types) after microtubule disruption and treatment with genistein. A strong reduction of NP uptake was observed after chlorpromazine treatment only in the case of 1321N1 cells. These outcomes suggested that the same NP might exploit different uptake mechanisms to enter different cell types.
Collapse
|
29
|
Juhász G, Földi I, Penke B. Systems biology of Alzheimer's disease: How diverse molecular changes result in memory impairment in AD. Neurochem Int 2011; 58:739-50. [DOI: 10.1016/j.neuint.2011.02.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 01/19/2011] [Accepted: 02/10/2011] [Indexed: 01/13/2023]
|
30
|
Sundborger A, Soderblom C, Vorontsova O, Evergren E, Hinshaw JE, Shupliakov O. An endophilin-dynamin complex promotes budding of clathrin-coated vesicles during synaptic vesicle recycling. J Cell Sci 2011; 124:133-43. [PMID: 21172823 DOI: 10.1242/jcs.072686] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Clathrin-mediated vesicle recycling in synapses is maintained by a unique set of endocytic proteins and interactions. We show that endophilin localizes in the vesicle pool at rest and in spirals at the necks of clathrin-coated pits (CCPs) during activity in lamprey synapses. Endophilin and dynamin colocalize at the base of the clathrin coat. Protein spirals composed of these proteins on lipid tubes in vitro have a pitch similar to the one observed at necks of CCPs in living synapses, and lipid tubules are thinner than those formed by dynamin alone. Tubulation efficiency and the amount of dynamin recruited to lipid tubes are dramatically increased in the presence of endophilin. Blocking the interactions of the endophilin SH3 domain in situ reduces dynamin accumulation at the neck and prevents the formation of elongated necks observed in the presence of GTPγS. Therefore, endophilin recruits dynamin to a restricted part of the CCP neck, forming a complex, which promotes budding of new synaptic vesicles.
Collapse
Affiliation(s)
- Anna Sundborger
- Department of Neuroscience, DBRM, Karolinska Institutet, 17177 Stockholm, Sweden
| | | | | | | | | | | |
Collapse
|
31
|
Denker A, Rizzoli SO. Synaptic vesicle pools: an update. Front Synaptic Neurosci 2010; 2:135. [PMID: 21423521 PMCID: PMC3059705 DOI: 10.3389/fnsyn.2010.00135] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2010] [Accepted: 08/02/2010] [Indexed: 12/04/2022] Open
Abstract
During the last few decades synaptic vesicles have been assigned to a variety of functional and morphological classes or “pools”. We have argued in the past (Rizzoli and Betz, 2005) that synaptic activity in several preparations is accounted for by the function of three vesicle pools: the readily releasable pool (docked at active zones and ready to go upon stimulation), the recycling pool (scattered throughout the nerve terminals and recycling upon moderate stimulation), and finally the reserve pool (occupying most of the vesicle clusters and only recycling upon strong stimulation). We discuss here the advancements in the vesicle pool field which took place in the ensuing years, focusing on the behavior of different pools under both strong stimulation and physiological activity. Several new findings have enhanced the three-pool model, with, for example, the disparity between recycling and reserve vesicles being underlined by the observation that the former are mobile, while the latter are “fixed”. Finally, a number of altogether new concepts have also evolved such as the current controversy on the identity of the spontaneously recycling vesicle pool.
Collapse
Affiliation(s)
- Annette Denker
- European Neuroscience Institute, DFG Center for Molecular Physiology of the Brain Göttingen, Germany
| | | |
Collapse
|
32
|
Synaptic activity and activity-dependent competition regulates axon arbor maturation, growth arrest, and territory in the retinotectal projection. J Neurosci 2010; 30:10939-51. [PMID: 20702722 DOI: 10.1523/jneurosci.1556-10.2010] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In the retinotectal projection, synapses guide retinal ganglion cell (RGC) axon arbor growth by promoting branch formation and by selectively stabilizing branches. To ask whether presynaptic function is required for this dual role of synapses, we have suppressed presynaptic function in single RGCs using targeted expression of tetanus toxin light-chain fused to enhanced green fluorescent protein (TeNT-Lc:EGFP). Time-lapse imaging of singly silenced axons as they arborize in the tectum of zebrafish larvae shows that presynaptic function is not required for stabilizing branches or for generating an arbor of appropriate complexity. However, synaptic activity does regulate two distinct aspects of arbor development. First, single silenced axons fail to arrest formation of highly dynamic but short-lived filopodia that are a feature of immature axons. Second, single silenced axons fail to arrest growth of established branches and so occupy significantly larger territories in the tectum than active axons. However, if activity-suppressed axons had neighbors that were also silent, axonal arbors appeared normal in size. A similar reversal in phenotype was observed when single TeNT-Lc:EGFP axons are grown in the presence of the NMDA receptor antagonist MK801 [(+)-5-methyl-10,11- dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate]. Although expansion of arbor territory is prevented when neighbors are silent, formation of transient filopodia is not. These results suggest that synaptic activity by itself regulates filopodia formation regardless of activity in neighboring cells but that the ability to arrest growth and focusing of axonal arbors in the target is an activity-dependent, competitive process.
Collapse
|
33
|
The role of cholesterol in the exo- and endocytosis of synaptic vesicles in frog motor nerve endings. ACTA ACUST UNITED AC 2010; 40:894-901. [PMID: 20680473 DOI: 10.1007/s11055-010-9338-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Indexed: 12/22/2022]
Abstract
Experiments on frog neuromuscular preparations using electrophysiological (two-electrode voltage clamping) and optical (with the fluorescent endocytic stain FM1-43) methods were performed to study the importance of membrane cholesterol in the exo- and endocytic cycle of synaptic vesicles (SV) in motor nerve endings in conditions of prolonged rhythmic stimulation of the motor nerve (20 impulses/sec, 3 min). Extraction of cholesterol from the superficial plasma membranes using methyl-beta-cyclodextrin (1 mM) led to marked changes in SV recycling. There was weakening of SV exocytosis and suppression of processes leading to the recovery of SV populations with rapid readiness to release neurotransmitter. When cholesterol was leached from the outer membranes and the membranes of SV undergoing recycling, these effects were supplemented by impairments to SV endocytosis and recycling. Thus, plasma membrane cholesterol plays a key role in the processes of exocytosis, while the efficiency of endocytosis depends on cholesterol in SV membranes.
Collapse
|
34
|
Villeneuve DL, Garcia-Reyero N, Martinović D, Cavallin JE, Mueller ND, Wehmas LC, Kahl MD, Linnum AL, Perkins EJ, Ankley GT. Influence of ovarian stage on transcript profiles in fathead minnow (Pimephales promelas) ovary tissue. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2010; 98:354-366. [PMID: 20363515 DOI: 10.1016/j.aquatox.2010.03.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 03/03/2010] [Accepted: 03/08/2010] [Indexed: 05/29/2023]
Abstract
Interpretation of toxicogenomic experiments conducted with ovary tissue from asynchronous-spawning small fish species is complicated by background variation in the relative abundance and proportion of follicles at different stages within the ovary tissue sample. This study employed both real-time quantitative polymerase chain reaction and a 15,000 gene oligonucleotide microarray to examine variation in the fathead minnow (Pimephales promelas) ovarian transcriptional profile as a function of quantitative and qualitative differences in ovarian histology. The objectives were to provide data that could potentially aid interpretation of future toxicogenomics experiments, identify putative stage-related transcriptional markers, and generate insights into basic biological regulation of asynchronous oocyte development. Multiple lines of evidence from the present study indicate that variation in the transcriptional profile is primarily dependent on the relative abundance of previtellogenic versus vitellogenic follicles in the ovary. Due to the relatively small proportions of mature ovulated follicles or atretic follicles in the overall follicle population, few potential transcriptional markers of maturation, ovulation, or atresia could be identified. However, among the 460 differentially expressed genes identified in the present study, several targets, including HtrA serine peptidase 3 (htra3), tissue inhibitor of metalloproteinase 3 (timp3), aquaporin 8 (aqp8), transgelin 2 like (tagln2), Nedd4 family interacting protein 2 (ndfip2), chemokine ligand 12a (cxcl12a), midkine-related growth factor (mdka), and jagged 1b (jag 1b) exhibited responses and functional properties that support them as candidate molecular markers of significant shift in gross ovarian stage. Genes associated with a diversity of functions including cellular development, morphogenesis, coated vesicle transport, sexual reproduction, and neuron development, among others, were statistically enriched within the list of 460 genes differentially expressed among different ovarian classes. Overall, results of this study provide insights into background variation in ovary transcript profiles that should aid and enhance the interpretation of toxicogenomic data generated in experiments conducted with small, asynchronous-spawning fish species.
Collapse
Affiliation(s)
- Daniel L Villeneuve
- US Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, 6201 Congdon Blvd., Duluth, MN 55804, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Nakano-Kobayashi A, Kasri NN, Newey SE, Van Aelst L. The Rho-linked mental retardation protein OPHN1 controls synaptic vesicle endocytosis via endophilin A1. Curr Biol 2009; 19:1133-9. [PMID: 19481455 DOI: 10.1016/j.cub.2009.05.022] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Revised: 05/05/2009] [Accepted: 05/08/2009] [Indexed: 11/19/2022]
Abstract
Neurons transmit information at chemical synapses by releasing neurotransmitters that are stored in synaptic vesicles (SVs) at the presynaptic site. After release, these vesicles need to be efficiently retrieved in order to maintain synaptic transmission. In concurrence, malfunctions in SV recycling have been associated with cognitive disorders. Oligophrenin-1 (OPHN1) encodes a Rho-GTPase-activating protein (Rho-GAP) whose loss of function causes X-linked mental retardation. OPHN1 is highly expressed in the brain and present both pre- and postsynaptically in neurons. Previous studies report that postsynaptic OPHN1 is important for dendritic spine morphogenesis, but its function at the presynaptic site remains largely unexplored. Here, we present evidence that reduced or defective OPHN1 signaling impairs SV cycling at hippocampal synapses. In particular, we show that OPHN1 knockdown affects the kinetic efficiency of endocytosis. We further demonstrate that OPHN1 forms a complex with endophilin A1, a protein implicated in membrane curvature generation during SV endocytosis and, importantly, that OPHN1's interaction with endophilin A1 and its Rho-GAP activity are important for its function in SV endocytosis. Our findings suggest that defects in efficient SV retrieval may contribute to the pathogenesis of OPHN1-linked cognitive impairment.
Collapse
Affiliation(s)
- Akiko Nakano-Kobayashi
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, New York, NY 11724, USA
| | | | | | | |
Collapse
|
36
|
Abstract
The aqueous compartment inside a vesicle makes its first connection with the extracellular fluid through an intermediate structure termed the exocytotic fusion pore. Progress in exocytosis can be measured in terms of the formation and growth of the fusion pore. The fusion pore has become a major focus of research in exocytosis; sensitive biophysical measurements have provided various glimpses of what it looks like and how it behaves. Some of the principal questions about the molecular mechanism of exocytosis can be cast explicitly in terms of properties and transitions of fusion pores. This Review will present current knowledge about fusion pores in Ca(2+)-triggered exocytosis, highlight recent advances and relate questions about fusion pores to broader issues concerning how cells regulate exocytosis and how nerve terminals release neurotransmitter.
Collapse
Affiliation(s)
- Meyer B Jackson
- Department of Physiology, University of Wisconsin School of Medicine and Public Health, 1300 University Avenue, Madison,WI 53706, USA.
| | | |
Collapse
|
37
|
Zorec R, Cousin MA, Seward EP. The fascinating and fleeting world of vesicle dynamics. J Physiol 2007. [DOI: 10.1113/jphysiol.2007.146324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
|
38
|
Corrigendum. J Physiol 2007. [DOI: 10.1113/jphysiol.2007.146373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
|