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Ouyang L, Sun Y, Lv D, Peng X, Liu X, Ci L, Zhang G, Yuan B, Li L, Fei J, Ma J, Liu X, Liao Y. miR-29cb2 promotes angiogenesis and osteogenesis by inhibiting HIF-3α in bone. iScience 2022; 25:103604. [PMID: 35005549 PMCID: PMC8718933 DOI: 10.1016/j.isci.2021.103604] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 10/25/2021] [Accepted: 12/08/2021] [Indexed: 12/14/2022] Open
Abstract
Coordination between osteogenesis and angiogenesis is required for bone homeostasis. Here, we show that miR-29cb2 is a bone-specific miRNA and plays critical roles on angiogenesis-osteogenesis coupling during bone remodeling. Mice with deletion of miR-29cb2 exhibit osteopenic phenotypes and osteoblast impairment, accompanied by pronounced decreases in specific H vessels. The decrease in bone miR-29cb2 was associated with pathological ovariectomy stimuli. Mechanistically, hypoxia-inducible factor (HIF)-3α, as a target for miR-29cb2, inhibits HIF-1α activity by competitively bonding with HIF-1β. Notably, miR-29cb2 in peripheral blood (PB) nearly is undetectable in sham and significantly increases in ovariectomy mice. Further evaluation from osteoporosis patients demonstrates similar signatures. ROC analysis shows miR-29cb2 in PB has higher sensitivity and specificity for diagnosing osteoporosis when compared with four clinical biomarkers. Collectively, these findings reveal that miR-29cb2 is essential for bone remodeling by inhibiting HIF-3α and elevated bone-specific miR-29cb2 in PB, which may be a promising biomarker for bone loss.
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Affiliation(s)
- Liping Ouyang
- Department of Pharmacy, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200336, China
- Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai 200336, China
| | - Yingxiao Sun
- Department of Pharmacy, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200336, China
| | - Dan Lv
- Department of Pharmacy, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200336, China
| | - Xiaochun Peng
- Department of Orthopaedics, The Sixth Affiliated People's Hospital, Shanghai Jiaotong University, Shanghai 200233, China
| | - Xiaoming Liu
- Department of Orthopedics, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200336, China
| | - Lei Ci
- Shanghai Engineering Research Center for Model Organisms, Shanghai Model Organisms Center, INC., Shanghai 201203, China
| | - Guoning Zhang
- Department of Orthopedics, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200336, China
| | - Bo Yuan
- Department of Pharmacy, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200336, China
| | - Ling Li
- Department of Pharmacy, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200336, China
| | - Jian Fei
- Shanghai Engineering Research Center for Model Organisms, Shanghai Model Organisms Center, INC., Shanghai 201203, China
- School of Life Science and Technology, Tongji University, Shanghai 200092, China
| | - Jun Ma
- Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai 200336, China
- Corresponding author
| | - Xuanyong Liu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
- Corresponding author
| | - Yun Liao
- Department of Pharmacy, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200336, China
- Corresponding author
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2
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Park DJ, Yun WS, Kim WC, Park JE, Lee SH, Ha S, Choi JS, Key J, Seo YJ. Improvement of stem cell-derived exosome release efficiency by surface-modified nanoparticles. J Nanobiotechnology 2020; 18:178. [PMID: 33287848 PMCID: PMC7720507 DOI: 10.1186/s12951-020-00739-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 11/28/2020] [Indexed: 02/08/2023] Open
Abstract
Background Mesenchymal stem cells (MSCs) are pluripotent stromal cells that release extracellular vesicles (EVs). EVs contain various growth factors and antioxidants that can positively affect the surrounding cells. Nanoscale MSC-derived EVs, such as exosomes, have been developed as bio-stable nano-type materials. However, some issues, such as low yield and difficulty in quantification, limit their use. We hypothesized that enhancing exosome production using nanoparticles would stimulate the release of intracellular molecules. Results The aim of this study was to elucidate the molecular mechanisms of exosome generation by comparing the internalization of surface-modified, positively charged nanoparticles and exosome generation from MSCs. We determined that Rab7, a late endosome and auto-phagosome marker, was increased upon exosome expression and was associated with autophagosome formation. Conclusions It was concluded that the nanoparticles we developed were transported to the lysosome by clathrin-mediated endocytosis. additionally, entered nanoparticles stimulated that autophagy related factors to release exosome from the MSC. MSC-derived exosomes using nanoparticles may increase exosome yield and enable the discovery of nanoparticle-induced genetic factors.![]()
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Affiliation(s)
- Dong Jun Park
- Department of Otorhinolaryngology, Yonsei University Wonju College of Medicine, 20 Ilsan-ro, Wonju, Gangwon-do, 26426, South Korea.,Research Institute of Hearing Enhancement, Yonsei University Wonju College of Medicine, Wonju, South Korea
| | - Wan Su Yun
- Department of Biomedical Engineering, Yonsei University, Wonju, South Korea
| | - Woo Cheol Kim
- Department of Biomedical Engineering, Yonsei University, Wonju, South Korea
| | - Jeong-Eun Park
- Department of Otorhinolaryngology, Yonsei University Wonju College of Medicine, 20 Ilsan-ro, Wonju, Gangwon-do, 26426, South Korea.,Research Institute of Hearing Enhancement, Yonsei University Wonju College of Medicine, Wonju, South Korea
| | - Su Hoon Lee
- Department of Otorhinolaryngology, Yonsei University Wonju College of Medicine, 20 Ilsan-ro, Wonju, Gangwon-do, 26426, South Korea.,Research Institute of Hearing Enhancement, Yonsei University Wonju College of Medicine, Wonju, South Korea
| | - Sunmok Ha
- Department of Biomedical Laboratory Science, College of Health Sciences, Yonsei University, Wonju, Republic of Korea
| | - Jin Sil Choi
- Department of Otorhinolaryngology, Yonsei University Wonju College of Medicine, 20 Ilsan-ro, Wonju, Gangwon-do, 26426, South Korea.,Research Institute of Hearing Enhancement, Yonsei University Wonju College of Medicine, Wonju, South Korea
| | - Jaehong Key
- Department of Biomedical Engineering, Yonsei University, Wonju, South Korea
| | - Young Joon Seo
- Department of Otorhinolaryngology, Yonsei University Wonju College of Medicine, 20 Ilsan-ro, Wonju, Gangwon-do, 26426, South Korea. .,Research Institute of Hearing Enhancement, Yonsei University Wonju College of Medicine, Wonju, South Korea.
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3
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Dunn VK, Gleason E. Inhibition of endocytosis suppresses the nitric oxide-dependent release of Cl- in retinal amacrine cells. PLoS One 2018; 13:e0201184. [PMID: 30044876 PMCID: PMC6059450 DOI: 10.1371/journal.pone.0201184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 07/10/2018] [Indexed: 11/18/2022] Open
Abstract
Our lab has previously shown that nitric oxide (NO) can alter the synaptic response properties of amacrine cells by releasing Cl- from internal acidic compartments. This alteration in the Cl- gradient brings about a positive shift in the reversal potential of the GABA-gated current, which can convert inhibitory synapses into excitatory synapses. Recently, we have shown that the cystic fibrosis transmembrane regulator (CFTR) Cl- channel is involved in the Cl- release. Here, we test the hypothesis that (acidic) synaptic vesicles are a source of NO-releasable Cl- in chick retinal amacrine cells. If SVs are a source of Cl-, then depleting synaptic vesicles should decrease the nitric oxide-dependent shift in the reversal potential of the GABA-gated current. The efficacy of four inhibitors of dynamin (dynasore, Dyngo 4a, Dynole 34-2, and MiTMAB) were evaluated. In order to deplete synaptic vesicles, voltage-steps were used to activate V-gated Ca2+ channels and stimulate the synaptic vesicle cycle either under control conditions or after treatment with the dynamin inhibitors. Voltage-ramps were used to measure the NO-dependent shift in the reversal potential of the GABA-gated currents under both conditions. Our results reveal that activating the synaptic vesicle cycle in the presence of dynasore or Dyngo 4a blocked the NO-dependent shift in EGABA. However, we also discovered that some dynamin inhibitors reduced Ca2+ signaling and L-type Ca2+ currents. Conversely, dynasore also increased neurotransmitter release at autaptic sites. To further resolve the mechanism underlying the inhibition of the NO-dependent shift in the reversal potential for the GABA-gated currents, we also tested the effects of the clathrin assembly inhibitor Pitstop 2 and found that this compound also inhibited the shift. These data provide evidence that dynamin inhibitors have multiple effects on amacrine cell synaptic transmission. These data also suggest that inhibition of endocytosis disrupts the ability of NO to elicit Cl- release from internal stores which may in part be due to depletion of synaptic vesicles.
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Affiliation(s)
- Vernon K. Dunn
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Evanna Gleason
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America
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4
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Wen X, Van Hook MJ, Grassmeyer JJ, Wiesman AI, Rich GM, Cork KM, Thoreson WB. Endocytosis sustains release at photoreceptor ribbon synapses by restoring fusion competence. J Gen Physiol 2018; 150:591-611. [PMID: 29555658 PMCID: PMC5881445 DOI: 10.1085/jgp.201711919] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 02/21/2018] [Indexed: 01/15/2023] Open
Abstract
Endocytosis is an essential process at sites of synaptic release. Not only are synaptic vesicles recycled by endocytosis, but the removal of proteins and lipids by endocytosis is needed to restore release site function at active zones after vesicle fusion. Synaptic exocytosis from vertebrate photoreceptors involves synaptic ribbons that serve to cluster vesicles near the presynaptic membrane. In this study, we hypothesize that this clustering increases the likelihood that exocytosis at one ribbon release site may disrupt release at an adjacent site and therefore that endocytosis may be particularly important for restoring release site competence at photoreceptor ribbon synapses. To test this, we combined optical and electrophysiological techniques in salamander rods. Pharmacological inhibition of dynamin-dependent endocytosis rapidly inhibits release from synaptic ribbons and slows recovery of ribbon-mediated release from paired pulse synaptic depression. Inhibiting endocytosis impairs the ability of second-order horizontal cells to follow rod light responses at frequencies as low as 2 Hz. Inhibition of endocytosis also increases lateral membrane mobility of individual Ca2+ channels, showing that it changes release site structure. Visualization of single synaptic vesicles by total internal reflection fluorescence microscopy reveals that inhibition of endocytosis reduces the likelihood of fusion among vesicles docked near ribbons and increases the likelihood that they will retreat from the membrane without fusion. Vesicle advance toward the membrane is also reduced, but the number of membrane-associated vesicles is not. Endocytosis therefore appears to be more important for restoring later steps in vesicle fusion than for restoring docking. Unlike conventional synapses in which endocytic restoration of release sites is evident only at high frequencies, endocytosis is needed to maintain release from rod ribbon synapses even at modest frequencies.
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Affiliation(s)
- Xiangyi Wen
- Department of Ophthalmology & Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE
- Department of Pharmacology & Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE
| | - Matthew J Van Hook
- Department of Ophthalmology & Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE
| | - Justin J Grassmeyer
- Department of Ophthalmology & Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE
- Department of Pharmacology & Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE
| | - Alex I Wiesman
- Department of Pharmacology & Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE
| | - Grace M Rich
- Department of Ophthalmology & Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE
| | - Karlene M Cork
- Department of Ophthalmology & Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE
- Department of Pharmacology & Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE
| | - Wallace B Thoreson
- Department of Ophthalmology & Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE
- Department of Pharmacology & Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE
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5
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Smart release of doxorubicin loaded on polyetheretherketone (PEEK) surface with 3D porous structure. Colloids Surf B Biointerfaces 2018; 163:175-183. [DOI: 10.1016/j.colsurfb.2017.12.045] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 12/21/2017] [Accepted: 12/23/2017] [Indexed: 01/16/2023]
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6
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Laghaei R, Ma J, Tarr TB, Homan AE, Kelly L, Tilvawala MS, Vuocolo BS, Rajasekaran HP, Meriney SD, Dittrich M. Transmitter release site organization can predict synaptic function at the neuromuscular junction. J Neurophysiol 2017; 119:1340-1355. [PMID: 29357458 DOI: 10.1152/jn.00168.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We have investigated the impact of transmitter release site (active zone; AZ) structure on synaptic function by physically rearranging the individual AZ elements in a previously published frog neuromuscular junction (NMJ) AZ model into the organization observed in a mouse NMJ AZ. We have used this strategy, purposefully without changing the properties of AZ elements between frog and mouse models (even though there are undoubtedly differences between frog and mouse AZ elements in vivo), to directly test how structure influences function at the level of an AZ. Despite a similarly ordered ion channel array substructure within both frog and mouse AZs, frog AZs are much longer and position docked vesicles in a different location relative to AZ ion channels. Physiologically, frog AZs have a lower probability of transmitter release compared with mouse AZs, and frog NMJs facilitate strongly during short stimulus trains in contrast with mouse NMJs that depress slightly. Using our computer modeling approach, we found that a simple rearrangement of the AZ building blocks of the frog model into a mouse AZ organization could recapitulate the physiological differences between these two synapses. These results highlight the importance of simple AZ protein organization to synaptic function. NEW & NOTEWORTHY A simple rearrangement of the basic building blocks in the frog neuromuscular junction model into a mouse transmitter release site configuration predicted the major physiological differences between these two synapses, suggesting that transmitter release site structure and organization is a strong predictor of function.
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Affiliation(s)
- Rozita Laghaei
- Biomedical Applications Group, Pittsburgh Supercomputing Center, Carnegie Mellon University , Pittsburgh, Pennsylvania
| | - Jun Ma
- Biomedical Applications Group, Pittsburgh Supercomputing Center, Carnegie Mellon University , Pittsburgh, Pennsylvania
| | - Tyler B Tarr
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Anne E Homan
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Lauren Kelly
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Megha S Tilvawala
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Blake S Vuocolo
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Harini P Rajasekaran
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Stephen D Meriney
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Markus Dittrich
- Biomedical Applications Group, Pittsburgh Supercomputing Center, Carnegie Mellon University , Pittsburgh, Pennsylvania.,Department of Neuroscience, Center for Neuroscience, University of Pittsburgh , Pittsburgh, Pennsylvania.,BioTeam Inc., Middleton , Massachusetts
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7
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Dynasore blocks evoked release while augmenting spontaneous synaptic transmission from primary visceral afferents. PLoS One 2017; 12:e0174915. [PMID: 28358887 PMCID: PMC5373620 DOI: 10.1371/journal.pone.0174915] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 03/17/2017] [Indexed: 11/27/2022] Open
Abstract
The recycling of vesicle membrane fused during exocytosis is essential to maintaining neurotransmission. The GTPase dynamin is involved in pinching off membrane to complete endocytosis and can be inhibited by dynasore resulting in activity-dependent depletion of release-competent synaptic vesicles. In rat brainstem slices, we examined the effects of dynasore on three different modes of glutamate release–spontaneous, evoked, and asynchronous release–at solitary tract (ST) inputs to neurons in the nucleus of the solitary tract (NTS). Intermittent bursts of stimuli to the ST interspersed with pauses in stimulation allowed examination of these three modes in each neuron continuously. Application of 100 μM dynasore rapidly increased the spontaneous EPSC (sEPSC) frequency which was followed by inhibition of both ST-evoked EPSCs (ST-EPSC) as well as asynchronous EPSCs. The onset of ST-EPSC failures was not accompanied by amplitude reduction–a pattern more consistent with conduction block than reduced probability of vesicle release. Neither result suggested that dynasore interrupted endocytosis. The dynasore response profile resembled intense presynaptic TRPV1 activation. The TRPV1 antagonist capsazepine failed to prevent dynasore increases in sEPSC frequency but did prevent the block of the ST-EPSC. In contrast, the TRPV1 antagonist JNJ 17203212 prevented both actions of dynasore in neurons with TRPV1-expressing ST inputs. In a neuron lacking TRPV1-expressing ST inputs, however, dynasore promptly increased sEPSC rate followed by block of ST-evoked EPSCs. Together our results suggest that dynasore actions on ST-NTS transmission are TRPV1-independent and changes in glutamatergic transmission are not consistent with changes in vesicle recycling and endocytosis.
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8
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Ge N, Wang D, Peng F, Li J, Qiao Y, Liu X. Poly(styrenesulfonate)-Modified Ni-Ti Layered Double Hydroxide Film: A Smart Drug-Eluting Platform. ACS APPLIED MATERIALS & INTERFACES 2016; 8:24491-24501. [PMID: 27579782 DOI: 10.1021/acsami.6b09697] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Drug-eluting stents (DESs) are widely used in the palliative treatment of many kinds of cancers. However, the covered polymers used in DESs are usually associated with stent migration and acute cholecystitis. Therefore, developing noncovered drug-loading layers on metal stents is of great importance. In this work, Ni-Ti layered double hydroxide (Ni-Ti LDH) films were prepared on the surface of nitinol via hydrothermal treatment, and the LDH films were further modified by poly(styrenesulfonate) (PSS). The anticancer drug doxorubicin could be effectively loaded onto the modified films, and drug release could be smartly controlled by the pH. Besides, the drug absorption amounts of cancer cells cultured on the films could be effectively improved. These results indicate that the PSS-modified LDH film may become a promising drug-loading platform that can be used in the design of DESs.
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Affiliation(s)
- Naijian Ge
- Intervention Center, Eastern Hepatobilialy Surgery Hospital, The Second Military Medical University , Shanghai 200438, China
| | - Donghui Wang
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , Shanghai 200050, China
| | - Feng Peng
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , Shanghai 200050, China
| | - Jinhua Li
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , Shanghai 200050, China
| | - Yuqin Qiao
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , Shanghai 200050, China
| | - Xuanyong Liu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , Shanghai 200050, China
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9
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Stone TW, Darlington LG, Forrest CM. Dependence receptor involvement in subtilisin-induced long-term depression and in long-term potentiation. Neuroscience 2016; 336:49-62. [PMID: 27590265 DOI: 10.1016/j.neuroscience.2016.08.043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 08/09/2016] [Accepted: 08/24/2016] [Indexed: 12/19/2022]
Abstract
The serine protease subtilisin induces a form of long-term depression (LTD) which is accompanied by a reduced expression of the axo-dendritic guidance molecule Unco-ordinated-5C (Unc-5C). One objective of the present work was to determine whether a loss of Unc-5C function contributed to subtilisin-induced LTD by using Unc-5C antibodies in combination with the pore-forming agents Triton X-100 (0.005%) or streptolysin O in rat hippocampal slices. In addition we have assessed the effect of subtilisin on the related dependence receptor Deleted in Colorectal Cancer (DCC) and used antibodies to this protein for functional studies. Field excitatory postsynaptic potentials (fEPSPs) were analyzed in rat hippocampal slices and protein extracts were used for Western blotting. Subtilisin produced a greater loss of DCC than of Unc-5C, but the antibodies had no effect on resting excitability or fEPSPs and did not modify subtilisin-induced LTD. However, antibodies to DCC but not Unc-5C did reduce the amplitude of theta-burst long-term potentiation (LTP). In addition, two inhibitors of endocytosis - dynasore and tat-gluR2(3Y) - were tested and, although the former compound had no effect on neurophysiological responses, tat-gluR2(3Y) did reduce the amplitude of subtilisin-induced LTD without affecting the expression of DCC or Unc-5C but with some loss of PostSynaptic Density Protein-95. The results support the view that the dependence receptor DCC may be involved in LTP and suggest that the endocytotic removal of a membrane protein or proteins may contribute to subtilisin-induced LTD, although it appears that neither Unc-5C nor DCC are involved in this process.
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Affiliation(s)
- Trevor W Stone
- Institute of Neurosciences and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
| | | | - Caroline M Forrest
- Institute of Neurosciences and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
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10
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Tissue-specific dynamin-1 deletion at the calyx of Held decreases short-term depression through a mechanism distinct from vesicle resupply. Proc Natl Acad Sci U S A 2016; 113:E3150-8. [PMID: 27185948 DOI: 10.1073/pnas.1520937113] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Dynamin is a large GTPase with a crucial role in synaptic vesicle regeneration. Acute dynamin inhibition impairs neurotransmitter release, in agreement with the protein's established role in vesicle resupply. Here, using tissue-specific dynamin-1 knockout [conditional knockout (cKO)] mice at a fast central synapse that releases neurotransmitter at high rates, we report that dynamin-1 deletion unexpectedly leads to enhanced steady-state neurotransmission and consequently less synaptic depression during brief periods of high-frequency stimulation. These changes are also accompanied by increased transmission failures. Interestingly, synaptic vesicle resupply and several other synaptic properties remain intact, including basal neurotransmission, presynaptic Ca(2+) influx, initial release probability, and postsynaptic receptor saturation and desensitization. However, acute application of Latrunculin B, a reagent known to induce actin depolymerization and impair bulk and ultrafast endocytosis, has a stronger effect on steady-state depression in cKO than in control and brings the depression down to a control level. The slow phase of presynaptic capacitance decay following strong stimulation is impaired in cKO; the rapid capacitance changes immediately after strong depolarization are also different between control and cKO and sensitive to Latrunculin B. These data raise the possibility that, in addition to its established function in regenerating synaptic vesicles, the endocytosis protein dynamin-1 may have an impact on short-term synaptic depression. This role comes into play primarily during brief high-frequency stimulation.
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11
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Arranz AM, Delbroek L, Van Kolen K, Guimarães MR, Mandemakers W, Daneels G, Matta S, Calafate S, Shaban H, Baatsen P, De Bock PJ, Gevaert K, Vanden Berghe P, Verstreken P, De Strooper B, Moechars D. LRRK2 functions in synaptic vesicle endocytosis through a kinase-dependent mechanism. J Cell Sci 2016; 128:541–52. [PMID: 25501810 DOI: 10.1242/jcs.158196] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Mutations in leucine-rich repeat kinase 2 (LRRK2) are associated with Parkinson’s disease, but the precise physiological function of the protein remains ill-defined. Recently, our group proposed a model in which LRRK2 kinase activity is part of an EndoA phosphorylation cycle that facilitates efficient vesicle formation at synapses in the Drosophila melanogaster neuromuscular junctions.Flies harbor only one Lrrk gene, which might encompass the functions of both mammalian LRRK1 and LRRK2. We therefore studied the role of LRRK2 in mammalian synaptic function and provide evidence that knockout or pharmacological inhibition of LRRK2 results in defects in synaptic vesicle endocytosis, altered synaptic morphology and impairments in neurotransmission. In addition, our data indicate that mammalian endophilin A1 (EndoA1,also known as SH3GL2) is phosphorylated by LRRK2 in vitro at T73 and S75, two residues in the BAR domain. Hence, our results indicate that LRRK2 kinase activity has an important role in the regulation of clathrin-mediated endocytosis of synaptic vesicles and subsequent neurotransmission at the synapse.
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12
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Linares-Clemente P, Rozas JL, Mircheski J, García-Junco-Clemente P, Martínez-López JA, Nieto-González JL, Vázquez ME, Pintado CO, Fernández-Chacón R. Different dynamin blockers interfere with distinct phases of synaptic endocytosis during stimulation in motoneurones. J Physiol 2015; 593:2867-88. [PMID: 25981717 DOI: 10.1113/jp270112] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Accepted: 04/29/2015] [Indexed: 01/05/2023] Open
Abstract
KEY POINTS Neurotransmitter release requires a tight coupling between synaptic vesicle exocytosis and endocytosis with dynamin being a key protein in that process. We used imaging techniques to examine the time course of endocytosis at mouse motor nerve terminals expressing synaptopHluorin, a genetically encoded reporter of the synaptic vesicle cycle. We separated two sequential phases of endocytosis taking place during the stimulation train: early and late endocytosis. Freshly released synaptic vesicle proteins are preferentially retrieved during the early phase, which is very sensitive to dynasore, an inhibitor of dynamin GTPase activity. Synaptic vesicle proteins pre-existing at the plasma membrane before the stimulation are preferentially retrieved during the late phase, which is very sensitive to myristyl trimethyl ammonium bromide (MitMAB), an inhibitor of the dynamin-phospholipid interaction. ABSTRACT Synaptic endocytosis is essential at nerve terminals to maintain neurotransmitter release by exocytosis. Here, at the neuromuscular junction of synaptopHluorin (spH) transgenic mice, we have used imaging to study exo- and endocytosis occurring simultaneously during nerve stimulation. We observed two endocytosis components, which occur sequentially during stimulation. The early component of endocytosis apparently internalizes spH molecules freshly exocytosed. This component was sensitive to dynasore, a blocker of dynamin 1 GTPase activity. In contrast, this early component was resistant to myristyl trimethyl ammonium bromide (MiTMAB), a competitive agent that blocks dynamin binding to phospholipid membranes. The late component of endocytosis is likely to internalize spH molecules that pre-exist at the plasma membrane before stimulation starts. This component was blocked by MiTMAB, perhaps by impairing the binding of dynamin or other key endocytic proteins to phospholipid membranes. Our study suggests the co-existence of two sequential synaptic endocytosis steps taking place during stimulation that are susceptible to pharmacological dissection: an initial step, preferentially sensitive to dynasore, that internalizes vesicular components immediately after they are released, and a MiTMAB-sensitive step that internalizes vesicular components pre-existing at the plasma membrane surface. In addition, we report that post-stimulus endocytosis also has several components with different sensitivities to dynasore and MiTMAB.
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Affiliation(s)
- Pedro Linares-Clemente
- Instituto de Biomedicina de Sevilla, IBiS, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, and CIBERNED, Seville, Spain
| | - José L Rozas
- Instituto de Biomedicina de Sevilla, IBiS, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, and CIBERNED, Seville, Spain
| | - Josif Mircheski
- Instituto de Biomedicina de Sevilla, IBiS, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, and CIBERNED, Seville, Spain
| | - Pablo García-Junco-Clemente
- Instituto de Biomedicina de Sevilla, IBiS, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, and CIBERNED, Seville, Spain
| | - José A Martínez-López
- Instituto de Biomedicina de Sevilla, IBiS, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, and CIBERNED, Seville, Spain
| | | | - M Eugenio Vázquez
- Departamento Química Orgánica y Centro Singular de Investigación en Química Biolóxica y Materiais Moleculares (CIQUS), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - C Oscar Pintado
- Centro Producción y Experimentación Animal, Universidad de Sevilla, Seville, Spain
| | - Rafael Fernández-Chacón
- Instituto de Biomedicina de Sevilla, IBiS, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, and CIBERNED, Seville, Spain
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13
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Luo F, Dittrich M, Cho S, Stiles JR, Meriney SD. Transmitter release is evoked with low probability predominately by calcium flux through single channel openings at the frog neuromuscular junction. J Neurophysiol 2015; 113:2480-9. [PMID: 25652927 DOI: 10.1152/jn.00879.2014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 01/31/2015] [Indexed: 01/07/2023] Open
Abstract
The quantitative relationship between presynaptic calcium influx and transmitter release critically depends on the spatial coupling of presynaptic calcium channels to synaptic vesicles. When there is a close association between calcium channels and synaptic vesicles, the flux through a single open calcium channel may be sufficient to trigger transmitter release. With increasing spatial distance, however, a larger number of open calcium channels might be required to contribute sufficient calcium ions to trigger vesicle fusion. Here we used a combination of pharmacological calcium channel block, high-resolution calcium imaging, postsynaptic recording, and 3D Monte Carlo reaction-diffusion simulations in the adult frog neuromuscular junction, to show that release of individual synaptic vesicles is predominately triggered by calcium ions entering the nerve terminal through the nearest open calcium channel. Furthermore, calcium ion flux through this channel has a low probability of triggering synaptic vesicle fusion (∼6%), even when multiple channels open in a single active zone. These mechanisms work to control the rare triggering of vesicle fusion in the frog neuromuscular junction from each of the tens of thousands of individual release sites at this large model synapse.
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Affiliation(s)
- Fujun Luo
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania; Center for the Neural Basis of Cognition, Pittsburgh, Pennsylvania
| | - Markus Dittrich
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania; Biomedical Applications Group, Pittsburgh Supercomputing Center, Carnegie Mellon University, Pittsburgh, Pennsylvania; and Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Soyoun Cho
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Joel R Stiles
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania; Biomedical Applications Group, Pittsburgh Supercomputing Center, Carnegie Mellon University, Pittsburgh, Pennsylvania; and Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Stephen D Meriney
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania; Center for the Neural Basis of Cognition, Pittsburgh, Pennsylvania;
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14
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Malomouzh AI, Mukhitov AR, Proskurina SE, Vyskocil F, Nikolsky EE. The effect of dynasore, a blocker of dynamin-dependent endocytosis, on spontaneous quantal and non-quantal release of acetylcholine in murine neuromuscular junctions. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2015; 459:330-3. [PMID: 25560208 DOI: 10.1134/s0012496614060052] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Indexed: 11/23/2022]
Affiliation(s)
- A I Malomouzh
- Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences, Kazan, 420111, Tatarstan, Russia,
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15
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Dason JS, Charlton MP. A novel extraction protocol to probe the role of cholesterol in synaptic vesicle recycling. Methods Mol Biol 2014; 1174:361-373. [PMID: 24947395 DOI: 10.1007/978-1-4939-0944-5_25] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Cholesterol helps to stabilize membrane fluidity and many membrane proteins interact with cholesterol and are functionally clustered in cholesterol rich "rafts." Synaptic vesicle (SV) membranes are enriched in cholesterol in comparison to other organelles. Attempts to study the function of this high cholesterol content have been hampered by the inability to extract cholesterol from SVs in live presynaptic terminals. Here, we describe a method to extract vesicular cholesterol using a temperature-sensitive Drosophila dynamin mutant, shibire-ts1 (shi), to trap SVs on the plasma membrane. Trapped SVs are more accessible to cholesterol extraction by the cholesterol chelator, methyl-β-cyclodextrin (MβCD). This method can likely be extended to extract other lipids from SVs and could also be used to add lipids. We speculate that this method could be used on mammalian preparations in conjunction with dynamin inhibitors.
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Affiliation(s)
- Jeffrey S Dason
- Department of Physiology, University of Toronto, Medical Sciences Building, 1 King's College Circle, Toronto, ON, Canada, M5S1A8,
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16
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McCluskey A, Daniel JA, Hadzic G, Chau N, Clayton EL, Mariana A, Whiting A, Gorgani NN, Lloyd J, Quan A, Moshkanbaryans L, Krishnan S, Perera S, Chircop M, von Kleist L, McGeachie AB, Howes MT, Parton RG, Campbell M, Sakoff JA, Wang X, Sun JY, Robertson MJ, Deane FM, Nguyen TH, Meunier FA, Cousin MA, Robinson PJ. Building a better dynasore: the dyngo compounds potently inhibit dynamin and endocytosis. Traffic 2013; 14:1272-89. [PMID: 24025110 PMCID: PMC4138991 DOI: 10.1111/tra.12119] [Citation(s) in RCA: 204] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 09/09/2013] [Accepted: 09/11/2013] [Indexed: 12/16/2022]
Abstract
Dynamin GTPase activity increases when it oligomerizes either into helices in the presence of lipid templates or into rings in the presence of SH3 domain proteins. Dynasore is a dynamin inhibitor of moderate potency (IC₅₀ ~ 15 μM in vitro). We show that dynasore binds stoichiometrically to detergents used for in vitro drug screening, drastically reducing its potency (IC₅₀ = 479 μM) and research tool utility. We synthesized a focused set of dihydroxyl and trihydroxyl dynasore analogs called the Dyngo™ compounds, five of which had improved potency, reduced detergent binding and reduced cytotoxicity, conferred by changes in the position and/or number of hydroxyl substituents. The Dyngo compound 4a was the most potent compound, exhibiting a 37-fold improvement in potency over dynasore for liposome-stimulated helical dynamin activity. In contrast, while dynasore about equally inhibited dynamin assembled in its helical or ring states, 4a and 6a exhibited >36-fold reduced activity against rings, suggesting that they can discriminate between helical or ring oligomerization states. 4a and 6a inhibited dynamin-dependent endocytosis of transferrin in multiple cell types (IC₅₀ of 5.7 and 5.8 μM, respectively), at least sixfold more potently than dynasore, but had no effect on dynamin-independent endocytosis of cholera toxin. 4a also reduced synaptic vesicle endocytosis and activity-dependent bulk endocytosis in cultured neurons and synaptosomes. Overall, 4a and 6a are improved and versatile helical dynamin and endocytosis inhibitors in terms of potency, non-specific binding and cytotoxicity. The data further suggest that the ring oligomerization state of dynamin is not required for clathrin-mediated endocytosis.
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Affiliation(s)
- Adam McCluskey
- Chemistry, Centre for Chemical Biology, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW, 2308, Australia
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17
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Yu J, Qian H, Wang JH. Upregulation of transmitter release probability improves a conversion of synaptic analogue signals into neuronal digital spikes. Mol Brain 2012; 5:26. [PMID: 22852823 PMCID: PMC3497613 DOI: 10.1186/1756-6606-5-26] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 07/07/2012] [Indexed: 12/01/2022] Open
Abstract
Action potentials at the neurons and graded signals at the synapses are primary codes in the brain. In terms of their functional interaction, the studies were focused on the influence of presynaptic spike patterns on synaptic activities. How the synapse dynamics quantitatively regulates the encoding of postsynaptic digital spikes remains unclear. We investigated this question at unitary glutamatergic synapses on cortical GABAergic neurons, especially the quantitative influences of release probability on synapse dynamics and neuronal encoding. Glutamate release probability and synaptic strength are proportionally upregulated by presynaptic sequential spikes. The upregulation of release probability and the efficiency of probability-driven synaptic facilitation are strengthened by elevating presynaptic spike frequency and Ca2+. The upregulation of release probability improves spike capacity and timing precision at postsynaptic neuron. These results suggest that the upregulation of presynaptic glutamate release facilitates a conversion of synaptic analogue signals into digital spikes in postsynaptic neurons, i.e., a functional compatibility between presynaptic and postsynaptic partners.
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Affiliation(s)
- Jiandong Yu
- State Key Lab for Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China 100101
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18
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Nguyen TH, Maucort G, Sullivan RKP, Schenning M, Lavidis NA, McCluskey A, Robinson PJ, Meunier FA. Actin- and dynamin-dependent maturation of bulk endocytosis restores neurotransmission following synaptic depletion. PLoS One 2012; 7:e36913. [PMID: 22629340 PMCID: PMC3358275 DOI: 10.1371/journal.pone.0036913] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Accepted: 04/09/2012] [Indexed: 11/18/2022] Open
Abstract
Bulk endocytosis contributes to the maintenance of neurotransmission at the amphibian neuromuscular junction by regenerating synaptic vesicles. How nerve terminals internalize adequate portions of the presynaptic membrane when bulk endocytosis is initiated before the end of a sustained stimulation is unknown. A maturation process, occurring at the end of the stimulation, is hypothesised to precisely restore the pools of synaptic vesicles. Using confocal time-lapse microscopy of FM1-43-labeled nerve terminals at the amphibian neuromuscular junction, we confirm that bulk endocytosis is initiated during a sustained tetanic stimulation and reveal that shortly after the end of the stimulation, nerve terminals undergo a maturation process. This includes a transient bulging of the plasma membrane, followed by the development of large intraterminal FM1-43-positive donut-like structures comprising large bulk membrane cisternae surrounded by recycling vesicles. The degree of bulging increased with stimulation frequency and the plasmalemma surface retrieved following the transient bulging correlated with the surface membrane internalized in bulk cisternae and recycling vesicles. Dyngo-4a, a potent dynamin inhibitor, did not block the initiation, but prevented the maturation of bulk endocytosis. In contrast, cytochalasin D, an inhibitor of actin polymerization, hindered both the initiation and maturation processes. Both inhibitors hampered the functional recovery of neurotransmission after synaptic depletion. Our data confirm that initiation of bulk endocytosis occurs during stimulation and demonstrates that a delayed maturation process controlled by actin and dynamin underpins the coupling between exocytosis and bulk endocytosis.
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Affiliation(s)
- Tam H. Nguyen
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Guillaume Maucort
- School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland, Australia
| | - Robert K. P. Sullivan
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
- Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, Queensland, Australia
| | - Mitja Schenning
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Nickolas A. Lavidis
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Adam McCluskey
- Chemistry, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, Australia
| | - Phillip J. Robinson
- Cell Signalling Unit, Children's Medical Research Institute, The University of Sydney, Sydney, Australia
| | - Frederic A. Meunier
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
- * E-mail:
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19
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Motorneurons Require Cysteine String Protein-α to Maintain the Readily Releasable Vesicular Pool and Synaptic Vesicle Recycling. Neuron 2012; 74:151-65. [DOI: 10.1016/j.neuron.2012.02.019] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/23/2012] [Indexed: 11/22/2022]
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20
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Reduced release probability prevents vesicle depletion and transmission failure at dynamin mutant synapses. Proc Natl Acad Sci U S A 2012; 109:E515-23. [PMID: 22308498 DOI: 10.1073/pnas.1121626109] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Endocytic recycling of synaptic vesicles after exocytosis is critical for nervous system function. At synapses of cultured neurons that lack the two "neuronal" dynamins, dynamin 1 and 3, smaller excitatory postsynaptic currents are observed due to an impairment of the fission reaction of endocytosis that results in an accumulation of arrested clathrin-coated pits and a greatly reduced synaptic vesicle number. Surprisingly, despite a smaller readily releasable vesicle pool and fewer docked vesicles, a strong facilitation, which correlated with lower vesicle release probability, was observed upon action potential stimulation at such synapses. Furthermore, although network activity in mutant cultures was lower, Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) activity was unexpectedly increased, consistent with the previous report of an enhanced state of synapsin 1 phosphorylation at CaMKII-dependent sites in such neurons. These changes were partially reversed by overnight silencing of synaptic activity with tetrodotoxin, a treatment that allows progression of arrested endocytic pits to synaptic vesicles. Facilitation was also counteracted by CaMKII inhibition. These findings reveal a mechanism aimed at preventing synaptic transmission failure due to vesicle depletion when recycling vesicle traffic is backed up by a defect in dynamin-dependent endocytosis and provide new insight into the coupling between endocytosis and exocytosis.
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21
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Orenbuch A, Ayelet O, Shulman Y, Yoav S, Lipstein N, Noa L, Bechar A, Amit B, Lavy Y, Yotam L, Brumer E, Eliaz B, Vasileva M, Mariya V, Kahn J, Joy K, Barki-Harrington L, Liza BH, Kuner T, Thomas K, Gitler D, Daniel G. Inhibition of exocytosis or endocytosis blocks activity-dependent redistribution of synapsin. J Neurochem 2011; 120:248-58. [PMID: 22066784 DOI: 10.1111/j.1471-4159.2011.07579.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The synaptic vesicle cycle encompasses the pre-synaptic events that drive neurotransmission. Influx of calcium leads to the fusion of synaptic vesicles with the plasma membrane and the release of neurotransmitter, closely followed by endocytosis. Vacated release sites are repopulated with vesicles which are then primed for release. When activity is intense, reserve vesicles may be mobilized to counteract an eventual decline in transmission. Recently, interplay between endocytosis and repopulation of the readily releasable pool of vesicles has been identified. In this study, we show that exo-endocytosis is necessary to enable detachment of synapsin from reserve pool vesicles during synaptic activity. We report that blockage of exocytosis in cultured mouse hippocampal neurons, either by tetanus toxin or by the deletion of munc13, inhibits the activity-dependent redistribution of synapsin from the pre-synaptic terminal into the axon. Likewise, perturbation of endocytosis with dynasore or by a dynamin dominant-negative mutant fully prevents synapsin redistribution. Such inhibition of synapsin redistribution occurred despite the efficient phosphorylation of synapsin at its protein kinase A/CaMKI site, indicating that disengagement of synapsin from the vesicles requires exocytosis and endocytosis in addition to phosphorylation. Our results therefore reveal hitherto unidentified feedback within the synaptic vesicle cycle involving the synapsin-managed reserve pool.
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Affiliation(s)
- Ayelet Orenbuch
- Department of Physiology and Neurobiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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22
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Harper CB, Martin S, Nguyen TH, Daniels SJ, Lavidis NA, Popoff MR, Hadzic G, Mariana A, Chau N, McCluskey A, Robinson PJ, Meunier FA. Dynamin inhibition blocks botulinum neurotoxin type A endocytosis in neurons and delays botulism. J Biol Chem 2011; 286:35966-35976. [PMID: 21832053 DOI: 10.1074/jbc.m111.283879] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The botulinum neurotoxins (BoNTs) are di-chain bacterial proteins responsible for the paralytic disease botulism. Following binding to the plasma membrane of cholinergic motor nerve terminals, BoNTs are internalized into an endocytic compartment. Although several endocytic pathways have been characterized in neurons, the molecular mechanism underpinning the uptake of BoNTs at the presynaptic nerve terminal is still unclear. Here, a recombinant BoNT/A heavy chain binding domain (Hc) was used to unravel the internalization pathway by fluorescence and electron microscopy. BoNT/A-Hc initially enters cultured hippocampal neurons in an activity-dependent manner into synaptic vesicles and clathrin-coated vesicles before also entering endosomal structures and multivesicular bodies. We found that inhibiting dynamin with the novel potent Dynasore analog, Dyngo-4a(TM), was sufficient to abolish BoNT/A-Hc internalization and BoNT/A-induced SNAP25 cleavage in hippocampal neurons. Dyngo-4a also interfered with BoNT/A-Hc internalization into motor nerve terminals. Furthermore, Dyngo-4a afforded protection against BoNT/A-induced paralysis at the rat hemidiaphragm. A significant delay of >30% in the onset of botulism was observed in mice injected with Dyngo-4a. Dynamin inhibition therefore provides a therapeutic avenue for the treatment of botulism and other diseases caused by pathogens sharing dynamin-dependent uptake mechanisms.
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Affiliation(s)
- Callista B Harper
- Queensland Brain Institute, the University of Queensland, Brisbane, Queensland 4072, Australia
| | - Sally Martin
- Queensland Brain Institute, the University of Queensland, Brisbane, Queensland 4072, Australia
| | - Tam H Nguyen
- Queensland Brain Institute, the University of Queensland, Brisbane, Queensland 4072, Australia
| | - Shari J Daniels
- Queensland Brain Institute, the University of Queensland, Brisbane, Queensland 4072, Australia
| | - Nickolas A Lavidis
- School of Biomedical Sciences, the University of Queensland, Brisbane, Queensland 4072, Australia
| | - Michel R Popoff
- Unité des Bactéries anaérobies et Toxines, Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris cedex, France
| | - Gordana Hadzic
- Centre for Chemical Biology, Chemistry Building, the University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Anna Mariana
- Children's Medical Research Institute, the University of Sydney, Sydney, New South Wales 2145, Australia
| | - Ngoc Chau
- Children's Medical Research Institute, the University of Sydney, Sydney, New South Wales 2145, Australia
| | - Adam McCluskey
- Centre for Chemical Biology, Chemistry Building, the University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Phillip J Robinson
- Children's Medical Research Institute, the University of Sydney, Sydney, New South Wales 2145, Australia
| | - Frederic A Meunier
- Queensland Brain Institute, the University of Queensland, Brisbane, Queensland 4072, Australia.
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23
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Rosa JM, Conde M, Nanclares C, Orozco A, Colmena I, de Pascual R, García AG, Gandía L. Paradoxical facilitation of exocytosis by inhibition of L-type calcium channels of bovine chromaffin cells. Biochem Biophys Res Commun 2011; 410:307-11. [PMID: 21663733 DOI: 10.1016/j.bbrc.2011.05.138] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 05/26/2011] [Indexed: 11/24/2022]
Abstract
Ca(2+) entry through the L-subtype (α(1D), Ca(v)1,3) of voltage-dependent calcium channels (VDCCs) seems to selectively regulate the endocytotic response after the application of a single depolarizing pulse to voltage-clamped bovine chromaffin cells. Here we have found that L channel blockade with nifedipine transformed the exocytotic responses elicited by a double-pulse protocol, from depression to facilitation. This apparent paradoxical effect was mimicked by pharmacological interventions that directly block endocytosis namely, dynasore, calmidazolium, GTP-γS and GDP-βS. This reinforces our view that Ca(2+) entry through PQ channels (α(1A); Ca(v)2.1) regulates fast exocytosis while Ca(2+) entry through L channels preferentially controls rapid endocytosis.
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Affiliation(s)
- Juliana M Rosa
- Instituto Teófilo Hernando, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
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