1
|
Asmerian H, Alberts J, Sanetra AM, Diaz AJ, Silm K. Role of adaptor protein complexes in generating functionally distinct synaptic vesicle pools. J Physiol 2024. [PMID: 39034608 DOI: 10.1113/jp286179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 07/05/2024] [Indexed: 07/23/2024] Open
Abstract
The synaptic vesicle (SV) cycle ensures the release of neurotransmitters and the replenishment of SVs to sustain neuronal activity. Multiple endocytosis and sorting pathways contribute to the recapture of the SV membrane and proteins after fusion. Adaptor protein (AP) complexes are among the critical components of the SV retrieval machinery. The canonical clathrin adaptor AP2 ensures the replenishment of most SVs across many neuronal populations. An alternative AP1/AP3-dependent process mediates the formation of a subset of SVs that differ from AP2 vesicles in molecular composition and respond preferentially during higher frequency firing. Furthermore, recent studies show that vesicular transporters for different neurotransmitters depend to a different extent on the AP3 pathway and this affects the release properties of the respective neurotransmitters. This review focuses on the current understanding of the AP-dependent molecular and functional diversity among SVs. We also discuss the contribution of these pathways to the regulation of neurotransmitter release across neuronal populations.
Collapse
Affiliation(s)
- Hrach Asmerian
- Center for Neural Science and Medicine, Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Jacob Alberts
- Center for Neural Science and Medicine, Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Anna M Sanetra
- Center for Neural Science and Medicine, Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Alexia J Diaz
- Center for Neural Science and Medicine, Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Katlin Silm
- Center for Neural Science and Medicine, Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| |
Collapse
|
2
|
Iguchi H, Katsuzawa T, Saruta C, Sadakata T, Kobayashi S, Sato Y, Sato A, Sano Y, Maezawa S, Shinoda Y, Furuichi T. Calcium-dependent activator protein for secretion 2 is involved in dopamine release in mouse midbrain neurons. Front Mol Neurosci 2024; 17:1444629. [PMID: 39092202 PMCID: PMC11291307 DOI: 10.3389/fnmol.2024.1444629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Accepted: 06/28/2024] [Indexed: 08/04/2024] Open
Abstract
The Ca2+-dependent activator protein for secretion (CAPS/CADPS) family protein facilitates catecholamine release through the dense-core vesicle exocytosis in model neuroendocrine cell lines. However, it remains unclear if it induces dopamine release in the central neurons. This study aimed to examine the expression and function of CADPS2, one of the two CADPS paralogs, in dopamine neurons of the mouse midbrain. This study shows that CADPS2 was expressed in tyrosine hydroxylase and the vesicular monoamine transporter 2 (VMAT2)-positive dopaminergic neurons of the midbrain samples and primary mesencephalic cell cultures. Subcellular fractions rich in dopamine were collected using immunoaffinity for CADPS2 from midbrain protein extracts. Cell imaging using fluorescent false neurotransmitter FFN511 as a substrate for VMAT2 showed decreased activity-dependent dopamine release in Cadps2-deficient cultures, compared to that in wild-type cultures. These results suggest that CADPS2 is involved in dopamine release from the central neurons, indicating its involvement in the central dopamine pathway.
Collapse
Affiliation(s)
- Hirotoshi Iguchi
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Japan
| | - Takumi Katsuzawa
- Department of Environmental Health, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Japan
| | - Chihiro Saruta
- Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Japan
| | - Tetsushi Sadakata
- Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Japan
- Education and Research Support Center, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Shota Kobayashi
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Japan
| | - Yumi Sato
- Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Japan
- Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Akira Sato
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Japan
- Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Japan
| | - Yoshitake Sano
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Japan
| | - So Maezawa
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Japan
| | - Yo Shinoda
- Department of Environmental Health, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Japan
- Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Japan
| | - Teiichi Furuichi
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Japan
- Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Japan
- Laboratory for Molecular Mechanisms of Brain Development, Center for Brain Science, RIKEN, Wako, Japan
| |
Collapse
|
3
|
Lee WL, Westergaard X, Hwu C, Hwu J, Fiala T, Lacefield C, Boltaev U, Mendieta AM, Lin L, Sonders MS, Brown KR, He K, Asher WB, Javitch JA, Sulzer D, Sames D. Molecular Design of SERTlight: A Fluorescent Serotonin Probe for Neuronal Labeling in the Brain. J Am Chem Soc 2024; 146:9564-9574. [PMID: 38557024 DOI: 10.1021/jacs.3c11617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
The serotonergic transmitter system plays fundamental roles in the nervous system in neurotransmission, synaptic plasticity, pathological processes, and therapeutic effects of antidepressants and psychedelics, as well as in the gastrointestinal and circulatory systems. We introduce a novel small molecule fluorescent agent, termed SERTlight, that specifically labels serotonergic neuronal cell bodies, dendrites, and axonal projections as a serotonin transporter (SERT) fluorescent substrate. SERTlight was developed by an iterative molecular design process, based on an aminoethyl-quinolone system, to integrate structural elements that impart SERT substrate activity, sufficient fluorescent brightness, and a broad absence of pharmacological activity, including at serotonin (5-hydroxytryptamine, 5HT) receptors, other G protein-coupled receptors (GPCRs), ion channels, and monoamine transporters. The high labeling selectivity is not achieved by high affinity binding to SERT itself but rather by a sufficient rate of SERT-mediated transport of SERTlight, resulting in accumulation of these molecules in 5HT neurons and yielding a robust and selective optical signal in the mammalian brain. SERTlight provides a stable signal, as it is not released via exocytosis nor by reverse SERT transport induced by 5HT releasers such as MDMA. SERTlight is optically, pharmacologically, and operationally orthogonal to a wide range of genetically encoded sensors, enabling multiplexed imaging. SERTlight enables labeling of distal 5HT axonal projections and simultaneous imaging of the release of endogenous 5HT using the GRAB5HT sensor, providing a new versatile molecular tool for the study of the serotonergic system.
Collapse
Affiliation(s)
- Wei-Li Lee
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Xavier Westergaard
- Department of Biological Sciences, Columbia University, New York, New York 10027, United States
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York 10032, United States
| | - Christopher Hwu
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Jennifer Hwu
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Tomas Fiala
- Department of Chemistry, Columbia University, New York, New York 10027, United States
- Laboratory of Organic Chemistry, ETH Zürich, D-CHAB, Vladimir-Prelog-Weg 3, 8093 Zürich, Switzerland
| | - Clay Lacefield
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York 10032, United States
- Division of Systems Neuroscience, New York State Psychiatric Institute, New York, New York 10032, United States
| | - Umed Boltaev
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Adriana M Mendieta
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Lisa Lin
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York 10032, United States
- Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, New York, New York 10032, United States
| | - Mark S Sonders
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York 10032, United States
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032, United States
| | - Keaon R Brown
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Keer He
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Wesley B Asher
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York 10032, United States
- Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, New York, New York 10032, United States
| | - Jonathan A Javitch
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York 10032, United States
- Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, New York, New York 10032, United States
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032, United States
| | - David Sulzer
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York 10032, United States
- Department of Neurology, Columbia University Irving Medical Center, New York, New York 10032, United States
- Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, New York, New York 10032, United States
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032, United States
| | - Dalibor Sames
- Department of Chemistry, Columbia University, New York, New York 10027, United States
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, New York 10027, United States
| |
Collapse
|
4
|
Ceballos CC, Ma L, Qin M, Zhong H. Prevalent co-release of glutamate and GABA throughout the mouse brain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.27.587069. [PMID: 38585864 PMCID: PMC10996720 DOI: 10.1101/2024.03.27.587069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Several neuronal populations in the brain transmit both the excitatory and inhibitory neurotransmitters, glutamate, and GABA, to downstream neurons. However, it remains largely unknown whether these opposing neurotransmitters are co-released onto the same postsynaptic neuron simultaneously or are independently transmitted at different time and locations (called co-transmission). Here, using whole-cell patch-clamp recording on acute mouse brain slices, we observed biphasic miniature postsynaptic currents, i.e., minis with time-locked excitatory and inhibitory currents, in striatal spiny projection neurons (SPNs). This observation cannot be explained by accidental coincidence of monophasic miniature excitatory and inhibitory postsynaptic currents (mEPSCs and mIPSCs, respectively), arguing for the co-release of glutamate and GABA. Interestingly, these biphasic minis could either be an mEPSC leading an mIPSC or vice versa. Although dopaminergic axons release both glutamate and GABA in the striatum, deletion of dopamine neurons did not eliminate biphasic minis, indicating that the co-release originates from another neuronal type. Importantly, we found that both types of biphasic minis were detected in other neuronal subtypes in the striatum as well as in nine out of ten additionally tested brain regions. Our results suggest that co-release of glutamate and GABA is a prevalent mode of neurotransmission in the brain.
Collapse
Affiliation(s)
- Cesar C Ceballos
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Lei Ma
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Maozhen Qin
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Haining Zhong
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| |
Collapse
|
5
|
Barcomb K, Ford CP. Alterations in neurotransmitter co-release in Parkinson's disease. Exp Neurol 2023; 370:114562. [PMID: 37802381 PMCID: PMC10842357 DOI: 10.1016/j.expneurol.2023.114562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 09/18/2023] [Accepted: 10/03/2023] [Indexed: 10/10/2023]
Abstract
Parkinson's disease is a neurological disorder characterized by degeneration of midbrain dopamine neurons, which results in numerous adaptations in basal ganglia circuits. Research over the past twenty-five years has identified that midbrain dopamine neurons of the substantia nigra pars compacta (SNc) and ventral tegmental area (VTA) co-release multiple other transmitters including glutamate and GABA, in addition to their canonical transmitter, dopamine. This review summarizes previous work characterizing neurotransmitter co-release from dopamine neurons, work examining potential changes in co-release dynamics that result in animal models of Parkinson's disease, and future opportunities for determining how dysfunction in co-release may contribute to circuit dysfunction in Parkinson's disease.
Collapse
Affiliation(s)
- Kelsey Barcomb
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO 80045, USA.
| | - Christopher P Ford
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO 80045, USA.
| |
Collapse
|
6
|
Jain S, Yee AG, Maas J, Gierok S, Xu H, Stansil J, Eriksen J, Nelson AB, Silm K, Ford CP, Edwards RH. Adaptor protein-3 produces synaptic vesicles that release phasic dopamine. Proc Natl Acad Sci U S A 2023; 120:e2309843120. [PMID: 37812725 PMCID: PMC10589613 DOI: 10.1073/pnas.2309843120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 09/06/2023] [Indexed: 10/11/2023] Open
Abstract
The burst firing of midbrain dopamine neurons releases a phasic dopamine signal that mediates reinforcement learning. At many synapses, however, high firing rates deplete synaptic vesicles (SVs), resulting in synaptic depression that limits release. What accounts for the increased release of dopamine by stimulation at high frequency? We find that adaptor protein-3 (AP-3) and its coat protein VPS41 promote axonal dopamine release by targeting vesicular monoamine transporter VMAT2 to the axon rather than dendrites. AP-3 and VPS41 also produce SVs that respond preferentially to high-frequency stimulation, independent of their role in axonal polarity. In addition, conditional inactivation of VPS41 in dopamine neurons impairs reinforcement learning, and this involves a defect in the frequency dependence of release rather than the amount of dopamine released. Thus, AP-3 and VPS41 promote the axonal polarity of dopamine release but enable learning by producing a distinct population of SVs tuned specifically to high firing frequency that confers the phasic release of dopamine.
Collapse
Affiliation(s)
- Shweta Jain
- Department of Physiology, University of California School of Medicine, San Francisco, CA94143
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
| | - Andrew G. Yee
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO80045
| | - James Maas
- Department of Physiology, University of California School of Medicine, San Francisco, CA94143
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
| | - Sarah Gierok
- Department of Physiology, University of California School of Medicine, San Francisco, CA94143
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
| | - Hongfei Xu
- Department of Physiology, University of California School of Medicine, San Francisco, CA94143
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
| | - Jasmine Stansil
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
| | - Jacob Eriksen
- Department of Physiology, University of California School of Medicine, San Francisco, CA94143
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
| | - Alexandra B. Nelson
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
- Aligning Science Across Parkinson’s Collaborative Research Network, Chevy Chase, MD20815
| | - Katlin Silm
- Department of Physiology, University of California School of Medicine, San Francisco, CA94143
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
| | - Christopher P. Ford
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO80045
- Aligning Science Across Parkinson’s Collaborative Research Network, Chevy Chase, MD20815
| | - Robert H. Edwards
- Department of Physiology, University of California School of Medicine, San Francisco, CA94143
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
- Aligning Science Across Parkinson’s Collaborative Research Network, Chevy Chase, MD20815
| |
Collapse
|
7
|
Jain S, Yee AG, Maas J, Gierok S, Xu H, Stansil J, Eriksen J, Nelson A, Silm K, Ford CP, Edwards RH. Adaptor Protein-3 Produces Synaptic Vesicles that Release Phasic Dopamine. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.07.552338. [PMID: 37609166 PMCID: PMC10441354 DOI: 10.1101/2023.08.07.552338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
The burst firing of midbrain dopamine neurons releases a phasic dopamine signal that mediates reinforcement learning. At many synapses, however, high firing rates deplete synaptic vesicles (SVs), resulting in synaptic depression that limits release. What accounts for the increased release of dopamine by stimulation at high frequency? We find that adaptor protein-3 (AP-3) and its coat protein VPS41 promote axonal dopamine release by targeting vesicular monoamine transporter VMAT2 to the axon rather than dendrites. AP-3 and VPS41 also produce SVs that respond preferentially to high frequency stimulation, independent of their role in axonal polarity. In addition, conditional inactivation of VPS41 in dopamine neurons impairs reinforcement learning, and this involves a defect in the frequency dependence of release rather than the amount of dopamine released. Thus, AP-3 and VPS41 promote the axonal polarity of dopamine release but enable learning by producing a novel population of SVs tuned specifically to high firing frequency that confers the phasic release of dopamine.
Collapse
Affiliation(s)
- Shweta Jain
- Department of Physiology, UCSF School of Medicine, San Francisco USA
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| | - Andrew G. Yee
- Department of Pharmacology, University of Colorado School of Medicine, Aurora USA
| | - James Maas
- Department of Physiology, UCSF School of Medicine, San Francisco USA
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| | - Sarah Gierok
- Department of Physiology, UCSF School of Medicine, San Francisco USA
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| | - Hongfei Xu
- Department of Physiology, UCSF School of Medicine, San Francisco USA
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| | - Jasmine Stansil
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| | - Jacob Eriksen
- Department of Physiology, UCSF School of Medicine, San Francisco USA
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| | - Alexandra Nelson
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| | - Katlin Silm
- Department of Physiology, UCSF School of Medicine, San Francisco USA
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| | - Christopher P. Ford
- Department of Pharmacology, University of Colorado School of Medicine, Aurora USA
| | - Robert H. Edwards
- Department of Physiology, UCSF School of Medicine, San Francisco USA
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| |
Collapse
|
8
|
Martí-Solans J, Børve A, Bump P, Hejnol A, Lynagh T. Peripheral and central employment of acid-sensing ion channels during early bilaterian evolution. eLife 2023; 12:81613. [PMID: 36821351 PMCID: PMC9949801 DOI: 10.7554/elife.81613] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 01/08/2023] [Indexed: 02/24/2023] Open
Abstract
Nervous systems are endowed with rapid chemosensation and intercellular signaling by ligand-gated ion channels (LGICs). While a complex, bilaterally symmetrical nervous system is a major innovation of bilaterian animals, the employment of specific LGICs during early bilaterian evolution is poorly understood. We therefore questioned bilaterian animals' employment of acid-sensing ion channels (ASICs), LGICs that mediate fast excitatory responses to decreases in extracellular pH in vertebrate neurons. Our phylogenetic analysis identified an earlier emergence of ASICs from the overarching DEG/ENaC (degenerin/epithelial sodium channel) superfamily than previously thought and suggests that ASICs were a bilaterian innovation. Our broad examination of ASIC gene expression and biophysical function in each major bilaterian lineage of Xenacoelomorpha, Protostomia, and Deuterostomia suggests that the earliest bilaterian ASICs were probably expressed in the periphery, before being incorporated into the brain as it emerged independently in certain deuterostomes and xenacoelomorphs. The loss of certain peripheral cells from Ecdysozoa after they separated from other protostomes likely explains their loss of ASICs, and thus the absence of ASICs from model organisms Drosophila and Caenorhabditis elegans. Thus, our use of diverse bilaterians in the investigation of LGIC expression and function offers a unique hypothesis on the employment of LGICs in early bilaterian evolution.
Collapse
Affiliation(s)
| | - Aina Børve
- Department of Biological Sciences, University of BergenBergenNorway
| | - Paul Bump
- Hopkins Marine Station, Department of Biology, Stanford UniversityPacific GroveUnited States
| | - Andreas Hejnol
- Department of Biological Sciences, University of BergenBergenNorway
| | | |
Collapse
|
9
|
Li H, Datunashvili M, Reyes RC, Voglmaier SM. Inositol hexakisphosphate kinases differentially regulate trafficking of vesicular glutamate transporters 1 and 2. Front Cell Neurosci 2022; 16:926794. [PMID: 35936490 PMCID: PMC9355605 DOI: 10.3389/fncel.2022.926794] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Accepted: 06/27/2022] [Indexed: 11/16/2022] Open
Abstract
Inositol pyrophosphates have been implicated in cellular signaling and membrane trafficking, including synaptic vesicle (SV) recycling. Inositol hexakisphosphate kinases (IP6Ks) and their product, diphosphoinositol pentakisphosphate (PP-IP5 or IP7), directly and indirectly regulate proteins important in vesicle recycling by the activity-dependent bulk endocytosis pathway (ADBE). In the present study, we show that two isoforms, IP6K1 and IP6K3, are expressed in axons. The role of the kinases in SV recycling are investigated using pharmacologic inhibition, shRNA knockdown, and IP6K1 and IP6K3 knockout mice. Live-cell imaging experiments use optical reporters of SV recycling based on vesicular glutamate transporter isoforms, VGLUT1- and VGLUT2-pHluorins (pH), which recycle differently. VGLUT1-pH recycles by classical AP-2 dependent endocytosis under moderate stimulation conditions, while VGLUT2-pH recycles using AP-1 and AP-3 adaptor proteins as well. Using a short stimulus to release the readily releasable pool (RRP), we show that IP6K1 KO increases exocytosis of both VGLUT1-and VGLUT2-pH, while IP6K3 KO decreases the amount of both transporters in the RRP. In electrophysiological experiments we measure glutamate signaling with short stimuli and under the intense stimulation conditions that trigger bulk endocytosis. IP6K1 KO increases synaptic facilitation and IP6K3 KO decreases facilitation compared to wild type in CA1 hippocampal Schaffer collateral synapses. After intense stimulation, the rate of endocytosis of VGLUT2-pH, but not VGLUT1-pH, is increased by knockout, knockdown, and pharmacologic inhibition of IP6Ks. Thus IP6Ks differentially affect the endocytosis of two SV protein cargos that use different endocytic pathways. However, while IP6K1 KO and IP6K3 KO exert similar effects on endocytosis after stimulation, the isoforms exert different effects on exocytosis earlier in the stimulus and on the early phase of glutamate release. Taken together, the data indicate a role for IP6Ks both in exocytosis early in the stimulation period and in endocytosis, particularly under conditions that may utilize AP-1/3 adaptors.
Collapse
|
10
|
Xu H, Chang F, Jain S, Heller BA, Han X, Liu Y, Edwards RH. SNX5 targets a monoamine transporter to the TGN for assembly into dense core vesicles by AP-3. J Cell Biol 2022; 221:e202106083. [PMID: 35426896 PMCID: PMC9016777 DOI: 10.1083/jcb.202106083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 12/06/2021] [Accepted: 02/16/2022] [Indexed: 11/22/2022] Open
Abstract
The time course of signaling by peptide hormones, neural peptides, and other neuromodulators depends on their storage inside dense core vesicles (DCVs). Adaptor protein 3 (AP-3) assembles the membrane proteins that confer regulated release of DCVs and is thought to promote their trafficking from endosomes directly to maturing DCVs. We now find that regulated monoamine release from DCVs requires sorting nexin 5 (SNX5). Loss of SNX5 disrupts trafficking of the vesicular monoamine transporter (VMAT) to DCVs. The mechanism involves a role for SNX5 in retrograde transport of VMAT from endosomes to the TGN. However, this role for SNX5 conflicts with the proposed function of AP-3 in trafficking from endosomes directly to DCVs. We now identify a transient role for AP-3 at the TGN, where it associates with DCV cargo. Thus, retrograde transport from endosomes by SNX5 enables DCV assembly at the TGN by AP-3, resolving the apparent antagonism. A novel role for AP-3 at the TGN has implications for other organelles that also depend on this adaptor.
Collapse
Affiliation(s)
- Hongfei Xu
- Departments of Neurology and Physiology, University of California San Francisco, San Francisco, CA
- Jiangsu Key Laboratory of Xenotransplantation, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Fei Chang
- Jiangsu Key Laboratory of Xenotransplantation, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Shweta Jain
- Departments of Neurology and Physiology, University of California San Francisco, San Francisco, CA
| | - Bradley Austin Heller
- Departments of Neurology and Physiology, University of California San Francisco, San Francisco, CA
| | - Xu Han
- Jiangsu Key Laboratory of Xenotransplantation, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Yongjian Liu
- Jiangsu Key Laboratory of Xenotransplantation, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
- Departments of Pharmacology and Biological Chemistry, University of Pittsburgh, Pittsburgh, PA
| | - Robert H. Edwards
- Departments of Neurology and Physiology, University of California San Francisco, San Francisco, CA
| |
Collapse
|
11
|
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
|
12
|
Pulido C, Ryan TA. Synaptic vesicle pools are a major hidden resting metabolic burden of nerve terminals. SCIENCE ADVANCES 2021; 7:eabi9027. [PMID: 34860552 PMCID: PMC8641928 DOI: 10.1126/sciadv.abi9027] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 10/14/2021] [Indexed: 05/15/2023]
Abstract
The brain is a metabolically fragile organ as compromises in fuel availability rapidly degrade cognitive function. Nerve terminals are likely loci of this vulnerability as they do not store sufficient ATP molecules, needing to synthesize them during activity or suffer acute degradation in performance. The ability of on-demand ATP synthesis to satisfy activity-driven ATP hydrolysis will depend additionally on the magnitude of local resting metabolic processes. We show here that synaptic vesicle (SV) pools are a major source of presynaptic basal energy consumption. This basal metabolic processes arises from SV-resident V-ATPases compensating for a hidden resting H+ efflux from the SV lumen. We show that this steady-state H+ efflux (i) is mediated by vesicular neurotransmitter transporters, (ii) is independent of the SV cycle, (iii) accounts for up to 44% of the resting synaptic energy consumption, and (iv) contributes substantially to nerve terminal intolerance of fuel deprivation.
Collapse
Affiliation(s)
- Camila Pulido
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
| | | |
Collapse
|
13
|
Opponent vesicular transporters regulate the strength of glutamatergic neurotransmission in a C. elegans sensory circuit. Nat Commun 2021; 12:6334. [PMID: 34732711 PMCID: PMC8566550 DOI: 10.1038/s41467-021-26575-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 09/22/2021] [Indexed: 11/30/2022] Open
Abstract
At chemical synapses, neurotransmitters are packaged into synaptic vesicles that release their contents in response to depolarization. Despite its central role in synaptic function, regulation of the machinery that loads vesicles with neurotransmitters remains poorly understood. We find that synaptic glutamate signaling in a C. elegans chemosensory circuit is regulated by antagonistic interactions between the canonical vesicular glutamate transporter EAT-4/VGLUT and another vesicular transporter, VST-1. Loss of VST-1 strongly potentiates glutamate release from chemosensory BAG neurons and disrupts chemotaxis behavior. Analysis of the circuitry downstream of BAG neurons shows that excess glutamate release disrupts behavior by inappropriately recruiting RIA interneurons to the BAG-associated chemotaxis circuit. Our data indicate that in vivo the strength of glutamatergic synapses is controlled by regulation of neurotransmitter packaging into synaptic vesicles via functional coupling of VGLUT and VST-1. The authors describe a vesicular transporter, VST-1, that is required in glutamatergic chemosensory neurons for chemotactic avoidance behavior in C. elegans. VST-1 antagonizes VGLUT-dependent packaging of glutamate into synaptic vesicles and determines the strength of synaptic glutamate signaling.
Collapse
|
14
|
Mori Y, Takenaka KI, Fukazawa Y, Takamori S. The endosomal Q-SNARE, Syntaxin 7, defines a rapidly replenishing synaptic vesicle recycling pool in hippocampal neurons. Commun Biol 2021; 4:981. [PMID: 34408265 PMCID: PMC8373932 DOI: 10.1038/s42003-021-02512-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 08/02/2021] [Indexed: 12/12/2022] Open
Abstract
Upon the arrival of repetitive stimulation at the presynaptic terminals of neurons, replenishment of readily releasable synaptic vesicles (SVs) with vesicles in the recycling pool is important for sustained neurotransmitter release. Kinetics of replenishment and the available pool size define synaptic performance. However, whether all SVs in the recycling pool are recruited for release with equal probability and speed is unknown. Here, based on comprehensive optical imaging of various presynaptic endosomal SNARE proteins in cultured hippocampal neurons, all of which are implicated in organellar membrane fusion in non-neuronal cells, we show that part of the recycling pool bearing the endosomal Q-SNARE, syntaxin 7 (Stx7), is preferentially mobilized for release during high-frequency repetitive stimulation. Recruitment of the SV pool marked with an Stx7-reporter requires actin polymerization, as well as activation of the Ca2+/calmodulin signaling pathway, reminiscent of rapidly replenishing SVs characterized previously in calyx of Held synapses. Furthermore, disruption of Stx7 function by overexpressing its N-terminal domain selectively abolished this pool. Thus, our data indicate that endosomal membrane fusion involving Stx7 forms rapidly replenishing vesicles essential for synaptic responses to high-frequency repetitive stimulation, and also highlight functional diversities of endosomal SNAREs in generating distinct exocytic vesicles in the presynaptic terminals. Yasunori Mori et al. find that a subset of neurotransmitter-bearing synaptic vesicles are marked for release by the endosomal Q-SNARE protein Stx7. They show that Stx7 function is necessary for the rapid replenishment of synaptic vesicles that is needed to sustain synaptic transmission during high-frequency stimulation.
Collapse
Affiliation(s)
- Yasunori Mori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto, Japan. .,Department of Biochemistry, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan.
| | - Koh-Ichiro Takenaka
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto, Japan
| | - Yugo Fukazawa
- Division of Brain Structure and Function, Research Center for Child Mental Development, Life Science Innovation Center, School of Medical Science, University of Fukui, Fukui, Japan
| | - Shigeo Takamori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto, Japan.
| |
Collapse
|
15
|
The Synaptic Vesicle Cycle Revisited: New Insights into the Modes and Mechanisms. J Neurosci 2020; 39:8209-8216. [PMID: 31619489 DOI: 10.1523/jneurosci.1158-19.2019] [Citation(s) in RCA: 100] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 07/31/2019] [Accepted: 08/03/2019] [Indexed: 02/01/2023] Open
Abstract
Neurotransmission is sustained by endocytosis and refilling of synaptic vesicles (SVs) locally within the presynapse. Until recently, a consensus formed that after exocytosis, SVs are recovered by either fusion pore closure (kiss-and-run) or clathrin-mediated endocytosis directly from the plasma membrane. However, recent data have revealed that SV formation is more complex than previously envisaged. For example, two additional recycling pathways have been discovered, ultrafast endocytosis and activity-dependent bulk endocytosis, in which SVs are regenerated from the internalized membrane and synaptic endosomes. Furthermore, these diverse modes of endocytosis appear to influence both the molecular composition and subsequent physiological role of individual SVs. In addition, previously unknown complexity in SV refilling and reclustering has been revealed. This review presents a modern view of the SV life cycle and discusses how neuronal subtype, physiological temperature, and individual activity patterns can recruit different endocytic modes to generate new SVs and sculpt subsequent presynaptic performance.
Collapse
|
16
|
Silm K, Yang J, Marcott PF, Asensio CS, Eriksen J, Guthrie DA, Newman AH, Ford CP, Edwards RH. Synaptic Vesicle Recycling Pathway Determines Neurotransmitter Content and Release Properties. Neuron 2019; 102:786-800.e5. [PMID: 31003725 PMCID: PMC6541489 DOI: 10.1016/j.neuron.2019.03.031] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 01/28/2019] [Accepted: 03/19/2019] [Indexed: 01/03/2023]
Abstract
In contrast to temporal coding by synaptically acting neurotransmitters such as glutamate, neuromodulators such as monoamines signal changes in firing rate. The two modes of signaling have been thought to reflect differences in release by different cells. We now find that midbrain dopamine neurons release glutamate and dopamine with different properties that reflect storage in different synaptic vesicles. The vesicles differ in release probability, coupling to presynaptic Ca2+ channels and frequency dependence. Although previous work has attributed variation in these properties to differences in location or cytoskeletal association of synaptic vesicles, the release of different transmitters shows that intrinsic differences in vesicle identity drive different modes of release. Indeed, dopamine but not glutamate vesicles depend on the adaptor protein AP-3, revealing an unrecognized linkage between the pathway of synaptic vesicle recycling and the properties of exocytosis. Storage of the two transmitters in different vesicles enables the transmission of distinct signals.
Collapse
Affiliation(s)
- Kätlin Silm
- Departments of Neurology and Physiology, Graduate Programs in Neuroscience and Cell Biology, Kavli Institute for Fundamental Neuroscience, Weill Institute for the Neurosciences, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Jing Yang
- Departments of Neurology and Physiology, Graduate Programs in Neuroscience and Cell Biology, Kavli Institute for Fundamental Neuroscience, Weill Institute for the Neurosciences, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Pamela F Marcott
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Cedric S Asensio
- Departments of Neurology and Physiology, Graduate Programs in Neuroscience and Cell Biology, Kavli Institute for Fundamental Neuroscience, Weill Institute for the Neurosciences, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Jacob Eriksen
- Departments of Neurology and Physiology, Graduate Programs in Neuroscience and Cell Biology, Kavli Institute for Fundamental Neuroscience, Weill Institute for the Neurosciences, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Daryl A Guthrie
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institutes of Drug Abuse - Intramural Research Program, Baltimore, MD 21224, USA
| | - Amy H Newman
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institutes of Drug Abuse - Intramural Research Program, Baltimore, MD 21224, USA
| | - Christopher P Ford
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Robert H Edwards
- Departments of Neurology and Physiology, Graduate Programs in Neuroscience and Cell Biology, Kavli Institute for Fundamental Neuroscience, Weill Institute for the Neurosciences, UCSF School of Medicine, San Francisco, CA 94143, USA.
| |
Collapse
|
17
|
Trudeau LE, El Mestikawy S. Glutamate Cotransmission in Cholinergic, GABAergic and Monoamine Systems: Contrasts and Commonalities. Front Neural Circuits 2018; 12:113. [PMID: 30618649 PMCID: PMC6305298 DOI: 10.3389/fncir.2018.00113] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 12/03/2018] [Indexed: 11/13/2022] Open
Abstract
Multiple discoveries made since the identification of vesicular glutamate transporters (VGLUTs) two decades ago revealed that many neuronal populations in the brain use glutamate in addition to their "primary" neurotransmitter. Such a mode of cotransmission has been detected in dopamine (DA), acetylcholine (ACh), serotonin (5-HT), norepinephrine (NE) and surprisingly even in GABA neurons. Interestingly, work performed by multiple groups during the past decade suggests that the use of glutamate as a cotransmitter takes different forms in these different populations of neurons. In the present review, we will provide an overview of glutamate cotransmission in these different classes of neurons, highlighting puzzling differences in: (1) the proportion of such neurons expressing a VGLUT in different brain regions and at different stages of development; (2) the sub-cellular localization of the VGLUT; (3) the localization of the VGLUT in relation to the neurons' other vesicular transporter; and (4) the functional role of glutamate cotransmission.
Collapse
Affiliation(s)
- Louis-Eric Trudeau
- CNS Research Group, Department of Pharmacology and Physiology, Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Salah El Mestikawy
- Department of Psychiatry, Faculty of Medicine, Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada.,Sorbonne Universités, Université Pierre et Marie Curie UM 119-CNRS UMR 8246-INSERM U1130, Neurosciences Paris Seine-Institut de Biologie Paris Seine (NPS-IBPS), Paris, France
| |
Collapse
|
18
|
Fortin GM, Ducrot C, Giguère N, Kouwenhoven WM, Bourque MJ, Pacelli C, Varaschin RK, Brill M, Singh S, Wiseman PW, Trudeau LÉ. Segregation of dopamine and glutamate release sites in dopamine neuron axons: regulation by striatal target cells. FASEB J 2018; 33:400-417. [PMID: 30011230 DOI: 10.1096/fj.201800713rr] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Dopamine (DA) is a key regulator of circuits controlling movement and motivation. A subset of midbrain DA neurons has been shown to express the vesicular glutamate transporter (VGLUT)2, underlying their capacity for glutamate release. Glutamate release is found mainly by DA neurons of the ventral tegmental area (VTA) and can be detected at terminals contacting ventral, but not dorsal, striatal neurons, suggesting the possibility that target-derived signals regulate the neurotransmitter phenotype of DA neurons. Whether glutamate can be released from the same terminals that release DA or from a special subset of axon terminals is unclear. Here, we provide in vitro and in vivo data supporting the hypothesis that DA and glutamate-releasing terminals in mice are mostly segregated and that striatal neurons regulate the cophenotype of midbrain DA neurons and the segregation of release sites. Our work unveils a fundamental feature of dual neurotransmission and plasticity of the DA system.-Fortin, G. M., Ducrot, C., Giguère, N., Kouwenhoven, W. M., Bourque, M.-J., Pacelli, C., Varaschin, R. K., Brill, M., Singh, S., Wiseman, P. W., Trudeau, L.-E. Segregation of dopamine and glutamate release sites in dopamine neuron axons: regulation by striatal target cells.
Collapse
Affiliation(s)
- Guillaume M Fortin
- Department of Pharmacology and Physiology, Université de Montréal, Montréal, Quebec, Canada
| | - Charles Ducrot
- Department of Pharmacology and Physiology, Université de Montréal, Montréal, Quebec, Canada.,Department of Neurosciences, Université de Montréal, Montreal, Quebec, Canada
| | - Nicolas Giguère
- Department of Pharmacology and Physiology, Université de Montréal, Montréal, Quebec, Canada.,Department of Neurosciences, Université de Montréal, Montreal, Quebec, Canada
| | | | - Marie-Josée Bourque
- Department of Pharmacology and Physiology, Université de Montréal, Montréal, Quebec, Canada
| | - Consiglia Pacelli
- Department of Pharmacology and Physiology, Université de Montréal, Montréal, Quebec, Canada
| | | | - Marion Brill
- Department of Pharmacology and Physiology, Université de Montréal, Montréal, Quebec, Canada
| | - Sherdeep Singh
- Department of Chemistry, McGill University, Montreal, Quebec, Canada; and
| | - Paul W Wiseman
- Department of Chemistry, McGill University, Montreal, Quebec, Canada; and
| | - Louis-Éric Trudeau
- Department of Pharmacology and Physiology, Université de Montréal, Montréal, Quebec, Canada.,Department of Neurosciences, Université de Montréal, Montreal, Quebec, Canada.,Groupe de Recherche sur le Système Nerveux Central, Faculty of Medicine, Université de Montréal, Montréal, Quebec, Canada
| |
Collapse
|
19
|
Hummer BH, de Leeuw NF, Burns C, Chen L, Joens MS, Hosford B, Fitzpatrick JAJ, Asensio CS. HID-1 controls formation of large dense core vesicles by influencing cargo sorting and trans-Golgi network acidification. Mol Biol Cell 2017; 28:3870-3880. [PMID: 29074564 PMCID: PMC5739301 DOI: 10.1091/mbc.e17-08-0491] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 10/05/2017] [Accepted: 10/16/2017] [Indexed: 12/19/2022] Open
Abstract
The peripheral membrane protein HID-1 localizes to the trans-Golgi network, where it contributes to the formation of large dense core vesicles of neuroendocrine cells by influencing cargo sorting and trans-Golgi network acidification. Large dense core vesicles (LDCVs) mediate the regulated release of neuropeptides and peptide hormones. They form at the trans-Golgi network (TGN), where their soluble content aggregates to form a dense core, but the mechanisms controlling biogenesis are still not completely understood. Recent studies have implicated the peripheral membrane protein HID-1 in neuropeptide sorting and insulin secretion. Using CRISPR/Cas9, we generated HID-1 KO rat neuroendocrine cells, and we show that the absence of HID-1 results in specific defects in peptide hormone and monoamine storage and regulated secretion. Loss of HID-1 causes a reduction in the number of LDCVs and affects their morphology and biochemical properties, due to impaired cargo sorting and dense core formation. HID-1 KO cells also exhibit defects in TGN acidification together with mislocalization of the Golgi-enriched vacuolar H+-ATPase subunit isoform a2. We propose that HID-1 influences early steps in LDCV formation by controlling dense core formation at the TGN.
Collapse
Affiliation(s)
- Blake H Hummer
- Department of Biological Sciences, University of Denver, Denver, CO 80210
| | - Noah F de Leeuw
- Department of Biological Sciences, University of Denver, Denver, CO 80210
| | - Christian Burns
- Department of Biological Sciences, University of Denver, Denver, CO 80210
| | - Lan Chen
- Department of Biological Sciences, University of Denver, Denver, CO 80210
| | - Matthew S Joens
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO 63110
| | - Bethany Hosford
- Department of Biological Sciences, University of Denver, Denver, CO 80210
| | - James A J Fitzpatrick
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO 63110
| | - Cedric S Asensio
- Department of Biological Sciences, University of Denver, Denver, CO 80210
| |
Collapse
|
20
|
α-Synuclein promotes dilation of the exocytotic fusion pore. Nat Neurosci 2017; 20:681-689. [PMID: 28288128 PMCID: PMC5404982 DOI: 10.1038/nn.4529] [Citation(s) in RCA: 200] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 02/05/2017] [Indexed: 01/08/2023]
Abstract
The protein α-synuclein has a central role in the pathogenesis of Parkinson’s disease (PD). Similar to other proteins that accumulate in neurodegenerative disease, however, the function of α-synuclein remains unknown. Localization to the nerve terminal suggests a role in neurotransmitter release and over-expression inhibits regulated exocytosis, but previous work has failed to identify a clear physiological defect in mice lacking all three synuclein isoforms. Using adrenal chromaffin cells and neurons, we now find that both over-expressed and endogenous synuclein serve to accelerate the kinetics of individual exocytotic events, promoting cargo discharge and reducing pore closure (‘kiss-and-run’). Thus, synuclein exerts dose-dependent effects on dilation of the exocytotic fusion pore. Remarkably, mutations that cause PD abrogate this property of α-synuclein without impairing its ability to inhibit exocytosis when over-expressed, indicating a selective defect in normal function.
Collapse
|
21
|
Stefanovic B, Spasojevic N, Jovanovic P, Jasnic N, Djordjevic J, Dronjak S. Melatonin mediated antidepressant-like effect in the hippocampus of chronic stress-induced depression rats: Regulating vesicular monoamine transporter 2 and monoamine oxidase A levels. Eur Neuropsychopharmacol 2016; 26:1629-37. [PMID: 27499503 DOI: 10.1016/j.euroneuro.2016.07.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 06/13/2016] [Accepted: 07/02/2016] [Indexed: 12/17/2022]
Abstract
The hippocampus is sensitive to stress which activates norepinephrine terminals deriving from the locus coeruleus. Melatonin exerts positive effects on the hippocampal neurogenic process and on depressive-like behaviour. Thus, in the present study, an examination was made of the effect of chronic melatonin treatment on norepinephrine content, synthesis, uptake, vesicular transport and degradation in the hippocampus of rats exposed to CUMS. This entailed quantifying the norephinephrine, mRNA and protein levels of DBH, NET, VMAT 2, MAO-A and COMT. The results show that CUMS evoked prolonged immobility. Melatonin treatment decreased immobility in comparison with the placebo group, reflecting an antidepressant-like effect. Compared with the placebo group, a dramatic decrease in norepinephrine content, decreased VMAT2 mRNA and protein and increased MAO-A protein levels in the hippocampus of the CUMS rats were observed. However, no significant differences in the levels of DBH, NET, COMT mRNA and protein and MAO-A mRNA levels between the placebo and the stressed groups were found. The results showed the restorative effects of melatonin on the stress-induced decline in the norepinephrine content of the hippocampus. It was observed that melatonin treatment in the CUMS rats prevented the stress-induced decrease in VMAT2 mRNA and protein levels, whereas it reduced the increase of the mRNA of COMT and protein levels of MAO-A. Chronic treatment with melatonin failed to alter the gene expression of DBH or NET in the hippocampus of the CUMS rats. Additionally, the results show that melatonin enhances VMAT2 expression and norepinephrine storage, whilst it reduces norepinephrine degrading enzymes.
Collapse
Affiliation(s)
- Bojana Stefanovic
- Institute of Nuclear Sciences "Vinca", Laboratory of Molecular Biology and Endocrinology, University of Belgrade, Belgrade, Serbia
| | - Natasa Spasojevic
- Institute of Nuclear Sciences "Vinca", Laboratory of Molecular Biology and Endocrinology, University of Belgrade, Belgrade, Serbia
| | - Predrag Jovanovic
- Institute of Nuclear Sciences "Vinca", Laboratory of Molecular Biology and Endocrinology, University of Belgrade, Belgrade, Serbia
| | - Nebojsa Jasnic
- Institute of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Jelena Djordjevic
- Institute of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Sladjana Dronjak
- Institute of Nuclear Sciences "Vinca", Laboratory of Molecular Biology and Endocrinology, University of Belgrade, Belgrade, Serbia.
| |
Collapse
|
22
|
Sulzer D, Cragg SJ, Rice ME. Striatal dopamine neurotransmission: regulation of release and uptake. ACTA ACUST UNITED AC 2016; 6:123-148. [PMID: 27141430 DOI: 10.1016/j.baga.2016.02.001] [Citation(s) in RCA: 236] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Dopamine (DA) transmission is governed by processes that regulate release from axonal boutons in the forebrain and the somatodendritic compartment in midbrain, and by clearance by the DA transporter, diffusion, and extracellular metabolism. We review how axonal DA release is regulated by neuronal activity and by autoreceptors and heteroreceptors, and address how quantal release events are regulated in size and frequency. In brain regions densely innervated by DA axons, DA clearance is due predominantly to uptake by the DA transporter, whereas in cortex, midbrain, and other regions with relatively sparse DA inputs, the norepinephrine transporter and diffusion are involved. We discuss the role of DA uptake in restricting the sphere of influence of DA and in temporal accumulation of extracellular DA levels upon successive action potentials. The tonic discharge activity of DA neurons may be translated into a tonic extracellular DA level, whereas their bursting activity can generate discrete extracellular DA transients.
Collapse
Affiliation(s)
- David Sulzer
- Depts of Psychiatry, Neurology, & Pharmacology, NY State Psychiatric Institute, Columbia University, New York, NY, USA
| | - Stephanie J Cragg
- Dept Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Margaret E Rice
- Depts of Neurosurgery & Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| |
Collapse
|
23
|
Wu Q, Xu H, Wang W, Chang F, Jiang Y, Liu Y. Retrograde trafficking of VMAT2 and its role in protein stability in non-neuronal cells. J Biomed Res 2016; 30:502-509. [PMID: 27924069 PMCID: PMC5138583 DOI: 10.7555/jbr.30.20160061] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 05/08/2016] [Accepted: 05/20/2016] [Indexed: 11/25/2022] Open
Abstract
Increasing evidence suggests that the impaired neuroprotection of vesicular monoamine transporter 2 (VMAT2) contributes to the pathogenesis of Parkinson's disease. That has been linked to aberrant subcellular retrograde trafficking as strongly indicated by recent genomic studies on familial Parkinson's diseases. However, whether VMAT2 function is regulated by retrograde trafficking is unknown. By using biochemistry and cell biology approaches, we have shown that VMAT2 was stringently localized to the trans-Golgi network and underwent retrograde trafficking in non-neuronal cells. The transporter also interacted with the key component of retromer, Vps35, biochemically and subcellularly. Using specific siRNA, we further showed that Vps35 depletion altered subcellular localization of VMAT2. Moreover, siRNA-mediated Vps35 knockdown also decreased the stability of VMAT2 as demonstrated by the reduced half-life. Thus, our work suggested that altered vesicular trafficking of VMAT2 may play a vital role in neuroprotection of the transporter as well as in the pathogenesis of Parkinson's disease.
Collapse
Affiliation(s)
- Qiuzi Wu
- Department of Physiology, School of Basic Medical Science, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Hongfei Xu
- Department of Physiology, School of Basic Medical Science, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Wei Wang
- Department of Physiology, School of Basic Medical Science, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Fei Chang
- Department of Physiology, School of Basic Medical Science, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Yu Jiang
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, USA
| | - Yongjian Liu
- Department of Physiology, School of Basic Medical Science, Nanjing Medical University, Nanjing, Jiangsu 211166, China.,Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, USA;
| |
Collapse
|
24
|
Tien NW, Kim T, Kerschensteiner D. Target-Specific Glycinergic Transmission from VGluT3-Expressing Amacrine Cells Shapes Suppressive Contrast Responses in the Retina. Cell Rep 2016; 15:1369-1375. [PMID: 27160915 DOI: 10.1016/j.celrep.2016.04.025] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 03/28/2016] [Accepted: 04/03/2016] [Indexed: 10/21/2022] Open
Abstract
Neurons that release more than one transmitter exist throughout the CNS. Yet, how these neurons deploy multiple transmitters and shape the function of specific circuits is not well understood. VGluT3-expressing amacrine cells (VG3-ACs) provide glutamatergic input to ganglion cells activated by contrast and motion. Using optogenetics, we find that VG3-ACs provide selective glycinergic input to a retinal ganglion cell type suppressed by contrast and motion (SbC-RGCs). Firing of SbC-RGCs is suppressed at light ON and OFF over a broad range of stimulus sizes. Anatomical circuit reconstructions reveal that VG3-ACs form inhibitory synapses preferentially on processes that link ON and OFF arbors of SbC-RGC dendrites. Removal of VG3-ACs from mature circuits reduces inhibition and attenuates spike suppression of SbC-RGCs in a contrast- and size-selective manner, illustrating the modularity of retinal circuits. VG3-ACs thus use dual transmitters in a target-specific manner and shape suppressive contrast responses in the retina by glycinergic transmission.
Collapse
Affiliation(s)
- Nai-Wen Tien
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA; Graduate Program in Neuroscience, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Tahnbee Kim
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA; Graduate Program in Neuroscience, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Daniel Kerschensteiner
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Neuroscience, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Biomedical Engineering, Washington University School of Medicine, Saint Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, Saint Louis, MO 63110, USA.
| |
Collapse
|
25
|
German CL, Baladi MG, McFadden LM, Hanson GR, Fleckenstein AE. Regulation of the Dopamine and Vesicular Monoamine Transporters: Pharmacological Targets and Implications for Disease. Pharmacol Rev 2016; 67:1005-24. [PMID: 26408528 DOI: 10.1124/pr.114.010397] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Dopamine (DA) plays a well recognized role in a variety of physiologic functions such as movement, cognition, mood, and reward. Consequently, many human disorders are due, in part, to dysfunctional dopaminergic systems, including Parkinson's disease, attention deficit hyperactivity disorder, and substance abuse. Drugs that modify the DA system are clinically effective in treating symptoms of these diseases or are involved in their manifestation, implicating DA in their etiology. DA signaling and distribution are primarily modulated by the DA transporter (DAT) and by vesicular monoamine transporter (VMAT)-2, which transport DA into presynaptic terminals and synaptic vesicles, respectively. These transporters are regulated by complex processes such as phosphorylation, protein-protein interactions, and changes in intracellular localization. This review provides an overview of 1) the current understanding of DAT and VMAT2 neurobiology, including discussion of studies ranging from those conducted in vitro to those involving human subjects; 2) the role of these transporters in disease and how these transporters are affected by disease; and 3) and how selected drugs alter the function and expression of these transporters. Understanding the regulatory processes and the pathologic consequences of DAT and VMAT2 dysfunction underlies the evolution of therapeutic development for the treatment of DA-related disorders.
Collapse
Affiliation(s)
- Christopher L German
- School of Dentistry (C.L.G., M.G.B., G.R.H., A.E.F.) and Department of Pharmacology and Toxicology (L.M.M., G.R.H.), University of Utah, Salt Lake City, Utah
| | - Michelle G Baladi
- School of Dentistry (C.L.G., M.G.B., G.R.H., A.E.F.) and Department of Pharmacology and Toxicology (L.M.M., G.R.H.), University of Utah, Salt Lake City, Utah
| | - Lisa M McFadden
- School of Dentistry (C.L.G., M.G.B., G.R.H., A.E.F.) and Department of Pharmacology and Toxicology (L.M.M., G.R.H.), University of Utah, Salt Lake City, Utah
| | - Glen R Hanson
- School of Dentistry (C.L.G., M.G.B., G.R.H., A.E.F.) and Department of Pharmacology and Toxicology (L.M.M., G.R.H.), University of Utah, Salt Lake City, Utah
| | - Annette E Fleckenstein
- School of Dentistry (C.L.G., M.G.B., G.R.H., A.E.F.) and Department of Pharmacology and Toxicology (L.M.M., G.R.H.), University of Utah, Salt Lake City, Utah
| |
Collapse
|
26
|
Pereira DB, Schmitz Y, Mészáros J, Merchant P, Hu G, Li S, Henke A, Lizardi-Ortiz JE, Karpowicz RJ, Morgenstern TJ, Sonders MS, Kanter E, Rodriguez PC, Mosharov EV, Sames D, Sulzer D. Fluorescent false neurotransmitter reveals functionally silent dopamine vesicle clusters in the striatum. Nat Neurosci 2016; 19:578-86. [PMID: 26900925 PMCID: PMC4853199 DOI: 10.1038/nn.4252] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2015] [Accepted: 01/15/2016] [Indexed: 12/16/2022]
Abstract
Neurotransmission at dopaminergic synapses has been studied with techniques that provide high temporal resolution, but cannot resolve individual synapses. To elucidate the spatial dynamics and heterogeneity of individual dopamine boutons, we developed fluorescent false neurotransmitter 200 (FFN200), a vesicular monoamine transporter 2 (VMAT2) substrate that selectively traces monoamine exocytosis in both neuronal cell culture and brain tissue. By monitoring electrically evoked Ca(2+) transients with GCaMP3 and FFN200 release simultaneously, we found that only a small fraction of dopamine boutons that exhibited Ca(2+) influx engaged in exocytosis, a result confirmed with activity-dependent loading of the endocytic probe FM1-43. Thus, only a low fraction of striatal dopamine axonal sites with uptake-competent VMAT2 vesicles are capable of transmitter release. This is consistent with the presence of functionally 'silent' dopamine vesicle clusters and represents, to the best of our knowledge, the first report suggestive of presynaptically silent neuromodulatory synapses.
Collapse
Affiliation(s)
- Daniela B. Pereira
- Department of Neurology, Columbia University Medical Center, New York, NY
| | - Yvonne Schmitz
- Department of Neurology, Columbia University Medical Center, New York, NY
| | - József Mészáros
- Department of Psychiatry, Columbia University Medical Center, New York, NY
| | | | - Gang Hu
- Department of Chemistry, Columbia University, New York, NY
| | - Shu Li
- Department of Chemistry, Columbia University, New York, NY
| | - Adam Henke
- Department of Chemistry, Columbia University, New York, NY
| | | | | | | | - Mark S. Sonders
- Department of Neurology, Columbia University Medical Center, New York, NY
- Department of Psychiatry, Columbia University Medical Center, New York, NY
| | - Ellen Kanter
- Department of Neurology, Columbia University Medical Center, New York, NY
| | | | - Eugene V. Mosharov
- Department of Neurology, Columbia University Medical Center, New York, NY
| | - Dalibor Sames
- Department of Chemistry, Columbia University, New York, NY
| | - David Sulzer
- Department of Neurology, Columbia University Medical Center, New York, NY
- Department of Psychiatry, Columbia University Medical Center, New York, NY
- Department of Pharmacology, Columbia University Medical Center, New York, NY
- Department of Neuroscience, New York Psychiatric Institute, New York, NY
| |
Collapse
|
27
|
Pathak D, Shields LY, Mendelsohn BA, Haddad D, Lin W, Gerencser AA, Kim H, Brand MD, Edwards RH, Nakamura K. The role of mitochondrially derived ATP in synaptic vesicle recycling. J Biol Chem 2015; 290:22325-36. [PMID: 26126824 DOI: 10.1074/jbc.m115.656405] [Citation(s) in RCA: 177] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Indexed: 01/03/2023] Open
Abstract
Synaptic mitochondria are thought to be critical in supporting neuronal energy requirements at the synapse, and bioenergetic failure at the synapse may impair neural transmission and contribute to neurodegeneration. However, little is known about the energy requirements of synaptic vesicle release or whether these energy requirements go unmet in disease, primarily due to a lack of appropriate tools and sensitive assays. To determine the dependence of synaptic vesicle cycling on mitochondrially derived ATP levels, we developed two complementary assays sensitive to mitochondrially derived ATP in individual, living hippocampal boutons. The first is a functional assay for mitochondrially derived ATP that uses the extent of synaptic vesicle cycling as a surrogate for ATP level. The second uses ATP FRET sensors to directly measure ATP at the synapse. Using these assays, we show that endocytosis has high ATP requirements and that vesicle reacidification and exocytosis require comparatively little energy. We then show that to meet these energy needs, mitochondrially derived ATP is rapidly dispersed in axons, thereby maintaining near normal levels of ATP even in boutons lacking mitochondria. As a result, the capacity for synaptic vesicle cycling is similar in boutons without mitochondria as in those with mitochondria. Finally, we show that loss of a key respiratory subunit implicated in Leigh disease markedly decreases mitochondrially derived ATP levels in axons, thus inhibiting synaptic vesicle cycling. This proves that mitochondria-based energy failure can occur and be detected in individual neurons that have a genetic mitochondrial defect.
Collapse
Affiliation(s)
- Divya Pathak
- From the Gladstone Institute of Neurological Disease, San Francisco, California 94158
| | - Lauren Y Shields
- From the Gladstone Institute of Neurological Disease, San Francisco, California 94158, the Department of Neurology and Graduate Programs in Neuroscience and Biomedical Sciences, University of California at San Francisco, San Francisco, California 94158
| | - Bryce A Mendelsohn
- From the Gladstone Institute of Neurological Disease, San Francisco, California 94158, the Department of Pediatrics, University of California at San Francisco, San Francisco, California 94143, and
| | - Dominik Haddad
- From the Gladstone Institute of Neurological Disease, San Francisco, California 94158
| | - Wei Lin
- From the Gladstone Institute of Neurological Disease, San Francisco, California 94158
| | - Akos A Gerencser
- the Buck Institute for Research on Aging, Novato, California 94945
| | - Hwajin Kim
- From the Gladstone Institute of Neurological Disease, San Francisco, California 94158
| | - Martin D Brand
- the Buck Institute for Research on Aging, Novato, California 94945
| | - Robert H Edwards
- the Department of Neurology and Graduate Programs in Neuroscience and Biomedical Sciences, University of California at San Francisco, San Francisco, California 94158
| | - Ken Nakamura
- From the Gladstone Institute of Neurological Disease, San Francisco, California 94158, the Department of Neurology and Graduate Programs in Neuroscience and Biomedical Sciences, University of California at San Francisco, San Francisco, California 94158,
| |
Collapse
|
28
|
The redistribution of Drosophila vesicular monoamine transporter mutants from synaptic vesicles to large dense-core vesicles impairs amine-dependent behaviors. J Neurosci 2014; 34:6924-37. [PMID: 24828646 DOI: 10.1523/jneurosci.0694-14.2014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Monoamine neurotransmitters are stored in both synaptic vesicles (SVs), which are required for release at the synapse, and large dense-core vesicles (LDCVs), which mediate extrasynaptic release. The contributions of each type of vesicular release to specific behaviors are not known. To address this issue, we generated mutations in the C-terminal trafficking domain of the Drosophila vesicular monoamine transporter (DVMAT), which is required for the vesicular storage of monoamines in both SVs and LDCVs. Deletion of the terminal 23 aa (DVMAT-Δ3) reduced the rate of endocytosis and localization of DVMAT to SVs, but supported localization to LDCVs. An alanine substitution mutation in a tyrosine-based motif (DVMAT-Y600A) also reduced sorting to SVs and showed an endocytic deficit specific to aminergic nerve terminals. Redistribution of DVMAT-Y600A from SV to LDCV fractions was also enhanced in aminergic neurons. To determine how these changes might affect behavior, we expressed DVMAT-Δ3 and DVMAT-Y600A in a dVMAT null genetic background that lacks endogenous dVMAT activity. When expressed ubiquitously, DVMAT-Δ3 showed a specific deficit in female fertility, whereas DVMAT-Y600A rescued behavior similarly to DVMAT-wt. In contrast, when expressed more specifically in octopaminergic neurons, both DVMAT-Δ3 and DVMAT-Y600A failed to rescue female fertility, and DVMAT-Y600A showed deficits in larval locomotion. DVMAT-Y600A also showed more severe dominant effects than either DVMAT-wt or DVMAT-Δ3. We propose that these behavioral deficits result from the redistribution of DVMAT from SVs to LDCVs. By extension, our data suggest that the balance of amine release from SVs versus that from LDCVs is critical for the function of some aminergic circuits.
Collapse
|
29
|
Vaaga CE, Borisovska M, Westbrook GL. Dual-transmitter neurons: functional implications of co-release and co-transmission. Curr Opin Neurobiol 2014; 29:25-32. [PMID: 24816154 DOI: 10.1016/j.conb.2014.04.010] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 04/16/2014] [Accepted: 04/17/2014] [Indexed: 11/18/2022]
Abstract
Co-transmission, the ability of a neuron to release multiple transmitters, has long been recognized in selected circuits. However, the release of multiple primary neurotransmitters from a single neuron is only beginning to be appreciated. Here we consider recent examples of co-transmission as well as co-release-the packaging of multiple neurotransmitters into a single vesicle. The properties associated with each mode of release greatly enhance the possible action of such neurons within circuits. The functional importance of dual- (or multi-) transmitter neurons extends beyond actions on postsynaptic receptors, due in part to differential spatial and temporal profiles of each neurotransmitter. Recent evidence also suggests that the dual-transmitter phenotype can be dynamically regulated during development and following injury or disease.
Collapse
Affiliation(s)
- Christopher E Vaaga
- Neuroscience Graduate Program, Oregon Health and Science University, Portland, OR, USA; Vollum Institute, Oregon Health and Science University, Portland, OR, USA
| | - Maria Borisovska
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA
| | - Gary L Westbrook
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA.
| |
Collapse
|
30
|
Favre-Besse FC, Poirel O, Bersot T, Kim-Grellier E, Daumas S, El Mestikawy S, Acher FC, Pietrancosta N. Design, synthesis and biological evaluation of small-azo-dyes as potent Vesicular Glutamate Transporters inhibitors. Eur J Med Chem 2014; 78:236-47. [PMID: 24686010 DOI: 10.1016/j.ejmech.2014.03.056] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 03/04/2014] [Accepted: 03/17/2014] [Indexed: 12/01/2022]
Abstract
Vesicular Glutamate Transporters (VGLUTs) allow the loading of presynapic glutamate vesicles and thus play a critical role in glutamatergic synaptic transmission. VGLUTs have proved to be involved in several major neuropathologies and directly correlated to clinical dementia in Alzheimer and Parkinson's disease. Accordingly VGLUT represent a key biological target or biomarker for neuropathology treatment or diagnostic. Yet, despite the pivotal role of VGLUTs, their pharmacology appears quite limited. Known competitive inhibitors are restricted to some dyes as Trypan Blue (TB) and glutamate mimics. This lack of pharmacological tools has heavily hampered VGLUT investigations. Here we report a rapid access to small molecules that combine benefits of TB and dicarboxylic quinolines (DCQs). Their ability to block vesicular glutamate uptake was evaluated. Several compounds displayed low micromolar inhibitory potency when size related compounds are thirty to forty times less potent (i.e. DCQ). We then confirmed the VGLUT selectivity by measuring the effect of the series on vesicular monoamine transport and on metabotropic glutamate receptor activity. These inhibitors are synthesized in only two steps and count among the best pharmacological tools for VGLUTs studies.
Collapse
Affiliation(s)
- Franck-Cyril Favre-Besse
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR8601 CNRS, Université Paris Descartes, Sorbonne Paris Cité, 45 rue des Saints-Pères, 75270 Paris 06, France
| | - Odile Poirel
- Institut National de la Santé et de la Recherche Médicale (INSERM), U952, Université Pierre et Marie Curie, 9 quai Saint Bernard, 75005 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR 7224, 9 quai Saint Bernard, 75005 Paris, France; Université Pierre et Marie Curie (UPMC) Paris 06, Pathophysiology of Central Nervous System Disorders, 9 quai Saint Bernard, 75005 Paris, France
| | - Tiphaine Bersot
- Institut National de la Santé et de la Recherche Médicale (INSERM), U952, Université Pierre et Marie Curie, 9 quai Saint Bernard, 75005 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR 7224, 9 quai Saint Bernard, 75005 Paris, France; Université Pierre et Marie Curie (UPMC) Paris 06, Pathophysiology of Central Nervous System Disorders, 9 quai Saint Bernard, 75005 Paris, France
| | - Elodie Kim-Grellier
- Institut National de la Santé et de la Recherche Médicale (INSERM), U952, Université Pierre et Marie Curie, 9 quai Saint Bernard, 75005 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR 7224, 9 quai Saint Bernard, 75005 Paris, France; Université Pierre et Marie Curie (UPMC) Paris 06, Pathophysiology of Central Nervous System Disorders, 9 quai Saint Bernard, 75005 Paris, France
| | - Stephanie Daumas
- Institut National de la Santé et de la Recherche Médicale (INSERM), U952, Université Pierre et Marie Curie, 9 quai Saint Bernard, 75005 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR 7224, 9 quai Saint Bernard, 75005 Paris, France; Université Pierre et Marie Curie (UPMC) Paris 06, Pathophysiology of Central Nervous System Disorders, 9 quai Saint Bernard, 75005 Paris, France
| | - Salah El Mestikawy
- Institut National de la Santé et de la Recherche Médicale (INSERM), U952, Université Pierre et Marie Curie, 9 quai Saint Bernard, 75005 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR 7224, 9 quai Saint Bernard, 75005 Paris, France; Université Pierre et Marie Curie (UPMC) Paris 06, Pathophysiology of Central Nervous System Disorders, 9 quai Saint Bernard, 75005 Paris, France; Douglas Hospital Research Center, Department of Psychiatry, McGill University, 6875 boulevard Lasalle Verdun, QC, Canada
| | - Francine C Acher
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR8601 CNRS, Université Paris Descartes, Sorbonne Paris Cité, 45 rue des Saints-Pères, 75270 Paris 06, France.
| | - Nicolas Pietrancosta
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR8601 CNRS, Université Paris Descartes, Sorbonne Paris Cité, 45 rue des Saints-Pères, 75270 Paris 06, France.
| |
Collapse
|
31
|
Self-assembly of VPS41 promotes sorting required for biogenesis of the regulated secretory pathway. Dev Cell 2013; 27:425-37. [PMID: 24210660 DOI: 10.1016/j.devcel.2013.10.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 08/06/2013] [Accepted: 10/11/2013] [Indexed: 12/22/2022]
Abstract
The regulated release of polypeptides has a central role in physiology, behavior, and development, but the mechanisms responsible for production of the large dense core vesicles (LDCVs) capable of regulated release have remained poorly understood. Recent work has implicated cytosolic adaptor protein AP-3 in the recruitment of LDCV membrane proteins that confer regulated release. However, AP-3 in mammals has been considered to function in the endolysosomal pathway and in the biosynthetic pathway only in yeast. We now find that the mammalian homolog of yeast VPS41, a member of the homotypic fusion and vacuole protein sorting (HOPS) complex that delivers biosynthetic cargo to the endocytic pathway in yeast, promotes LDCV formation through a common mechanism with AP-3, indicating a conserved role for these proteins in the biosynthetic pathway. VPS41 also self-assembles into a lattice, suggesting that it acts as a coat protein for AP-3 in formation of the regulated secretory pathway.
Collapse
|
32
|
Sirkis DW, Edwards RH, Asensio CS. Widespread dysregulation of peptide hormone release in mice lacking adaptor protein AP-3. PLoS Genet 2013; 9:e1003812. [PMID: 24086151 PMCID: PMC3784564 DOI: 10.1371/journal.pgen.1003812] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 08/06/2013] [Indexed: 12/13/2022] Open
Abstract
The regulated secretion of peptide hormones, neural peptides and many growth factors depends on their sorting into large dense core vesicles (LDCVs) capable of regulated exocytosis. LDCVs form at the trans-Golgi network, but the mechanisms that sort proteins to this regulated secretory pathway and the cytosolic machinery that produces LDCVs remain poorly understood. Recently, we used an RNAi screen to identify a role for heterotetrameric adaptor protein AP-3 in regulated secretion and in particular, LDCV formation. Indeed, mocha mice lacking AP-3 have a severe neurological and behavioral phenotype, but this has been attributed to a role for AP-3 in the endolysosomal rather than biosynthetic pathway. We therefore used mocha mice to determine whether loss of AP-3 also dysregulates peptide release in vivo. We find that adrenal chromaffin cells from mocha animals show increased constitutive exocytosis of both soluble cargo and LDCV membrane proteins, reducing the response to stimulation. We also observe increased basal release of both insulin and glucagon from pancreatic islet cells of mocha mice, suggesting a global disturbance in the release of peptide hormones. AP-3 exists as both ubiquitous and neuronal isoforms, but the analysis of mice lacking each of these isoforms individually and together shows that loss of both is required to reproduce the effect of the mocha mutation on the regulated pathway. In addition, we show that loss of the related adaptor protein AP-1 has a similar effect on regulated secretion but exacerbates the effect of AP-3 RNAi, suggesting distinct roles for the two adaptors in the regulated secretory pathway.
Collapse
Affiliation(s)
- Daniel W. Sirkis
- Graduate Program in Pharmaceutical Sciences and Pharmacogenomics, University of California San Francisco, San Francisco, California, United States of America
- Departments of Physiology and Neurology, University of California San Francisco, San Francisco, California, United States of America
| | - Robert H. Edwards
- Graduate Program in Pharmaceutical Sciences and Pharmacogenomics, University of California San Francisco, San Francisco, California, United States of America
- Departments of Physiology and Neurology, University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
| | - Cédric S. Asensio
- Departments of Physiology and Neurology, University of California San Francisco, San Francisco, California, United States of America
| |
Collapse
|
33
|
Abstract
We now know of a surprising number of cases where single neurons contain multiple neurotransmitters. Neurons that contain a fast-acting neurotransmitter, such as glutamate or GABA, and a modulatory transmitter, such as dopamine, are a particularly interesting case because they presumably serve dual signaling functions. The olfactory bulb contains a large population of GABA- and dopamine-containing neurons that have been implicated in normal olfaction as well as in Parkinson's disease. Yet, they have been classified as nonexocytotic catecholamine neurons because of the apparent lack of vesicular monoamine transporters. Thus, we examined how dopamine is stored and released from tyrosine hydroxylase-positive GFP (TH(+)-GFP) mouse periglomerular neurons in vitro. TH(+) cells expressed both VMAT2 (vesicular monoamine transporter 2) and VGAT (vesicular GABA transporter), consistent with vesicular storage of both dopamine and GABA. Carbon fiber amperometry revealed that release of dopamine was quantal and calcium-dependent, but quantal size was much less than expected for large dense core vesicles, suggesting that release originated from small clear vesicles identified by electron microscopy. A single action potential in a TH(+) neuron evoked a brief GABA-mediated synaptic current, whereas evoked dopamine release was asynchronous, lasting for tens of seconds. Our data suggest that dopamine and GABA serve temporally distinct roles in these dual transmitter neurons.
Collapse
|
34
|
Abstract
Numerous neurons release two transmitters of low molecular mass, but it is controversial whether they are localized within the same synaptic vesicle, with the single exception of GABA and glycine because they are ferried into the vesicle by the same transporter. Retinal dopaminergic (DAergic) amacrine cells synthesize both dopamine (DA) and GABA. Both transmitters are released over the entire cell surface and act on neighboring and distant neurons by volume transmission, but, in addition, DAergic cells establish GABAergic synapses onto AII amacrine cells, the neurons that transfer rod signals to cone bipolars. By combining recordings of DA and GABA release from isolated, genetically identified perikarya of DAergic cells from the mouse retina, we observed that a proportion of the events of DA and GABA exocytosis were simultaneous, suggesting corelease. Furthermore, a proportion of the secretory organelles in the perikaryon and synaptic endings of DAergic cells contained both vesicular transporters for DA [vesicular monoamine transporter 2 (VMAT2)] and GABA [vesicular GABA transporter (VGAT)]. Because the majority of the DA release events concerned a single transmitter and organelles were present that contained a single transporter, either VMAT2 or VGAT, we conclude that the secretory organelles of DAergic cells contain variable concentrations of the two transmitters, which are in turn determined by a variable mixture of the two transporter molecules in their limiting membrane. This variability can be explained if the relative numbers of transporter molecules is determined stochastically during the budding of the somatic organelles from the trans-Golgi network or the retrieval of the vesicular membrane from the plasmalemma after exocytosis.
Collapse
|
35
|
Calbindin controls release probability in ventral tegmental area dopamine neurons. Nat Neurosci 2012; 15:813-5. [PMID: 22544312 DOI: 10.1038/nn.3099] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Accepted: 04/02/2012] [Indexed: 11/08/2022]
Abstract
Relatively little is known about the molecular control of midbrain dopamine release. Using high-fidelity imaging of pHluorin-tagged vesicular monoamine transporter 2 in dopamine neurons, we found that exocytosis was more loosely coupled to calcium entry than in fast synapses. In ventral tegmental area neurons, this allows exocytosis to be efficiently controlled by a native fast calcium buffer, calbindin-D28k, maintaining a lower vesicular release probability compared with substantia nigra neurons.
Collapse
|
36
|
Neurotransmitter segregation: functional and plastic implications. Prog Neurobiol 2012; 97:277-87. [PMID: 22531669 DOI: 10.1016/j.pneurobio.2012.04.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 03/21/2012] [Accepted: 04/10/2012] [Indexed: 12/25/2022]
Abstract
Synaptic cotransmission is the ability of neurons to use more than one transmitter to convey synaptic signals. Cotransmission was originally described as the presence of a classic transmitter, which conveys main signal, along one or more cotransmitters that modulate transmission, later on, it was found cotransmission of classic transmitters. It has been generally accepted that neurons store and release the same set of transmitters in all their synaptic processes. However, some findings that show axon endings of individual neurons storing and releasing different sets of transmitters, are not in accordance with this assumption, and give support to the hypothesis that neurons can segregate transmitters to different synapses. Here, we review the studies showing segregation of transmitters in invertebrate and mammalian central nervous system neurons, and correlate them with our results obtained in sympathetic neurons. Our data show that these neurons segregate even classic transmitters to separated axons. Based on our data we suggest that segregation is a plastic phenomenon and responds to functional synaptic requirements, and to 'environmental' cues such as neurotrophins. We propose that neurons have the machinery to guide the different molecules required in synaptic transmission through axons and sort them to different axon endings. We believe that transmitter segregation improves neuron interactions during cotransmission and gives them selective and better control of synaptic plasticity.
Collapse
|
37
|
Zhang H, Sulzer D. Regulation of striatal dopamine release by presynaptic auto- and heteroreceptors. ACTA ACUST UNITED AC 2012; 2:5-13. [PMID: 22712055 DOI: 10.1016/j.baga.2011.11.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Striatal dopamine neurotransmission is critical for normal voluntary movement, affect and cognition. Dysfunctions of its regulation are implicated in a broad range of behaviors and disorders including Parkinson's disease, schizophrenia and drug abuse. Extracellular dopamine levels result from a dynamic equilibrium between release and reuptake by dopaminergic terminals. Both processes are regulated by multiple mechanisms. Here we review data characterizing how dopamine levels are regulated by presynaptic autoreceptors and heteroreceptors, an area intensively investigated due to advances in real time electrochemical detection of extracellular dopamine, i.e., fast-scan cyclic voltammetry and amperometry, and the development of mutant mouse lines with deletions for specific receptors.
Collapse
Affiliation(s)
- Hui Zhang
- Department of Psychiatry and Neurology, Columbia University, New York
| | | |
Collapse
|
38
|
Rice ME, Patel JC, Cragg SJ. Dopamine release in the basal ganglia. Neuroscience 2011; 198:112-37. [PMID: 21939738 PMCID: PMC3357127 DOI: 10.1016/j.neuroscience.2011.08.066] [Citation(s) in RCA: 193] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 08/22/2011] [Accepted: 08/26/2011] [Indexed: 10/17/2022]
Abstract
Dopamine (DA) is a key transmitter in the basal ganglia, yet DA transmission does not conform to several aspects of the classic synaptic doctrine. Axonal DA release occurs through vesicular exocytosis and is action potential- and Ca²⁺-dependent. However, in addition to axonal release, DA neurons in midbrain exhibit somatodendritic release by an incompletely understood, but apparently exocytotic, mechanism. Even in striatum, axonal release sites are controversial, with evidence for DA varicosities that lack postsynaptic specialization, and largely extrasynaptic DA receptors and transporters. Moreover, DA release is often assumed to reflect a global response to a population of activities in midbrain DA neurons, whether tonic or phasic, with precise timing and specificity of action governed by other basal ganglia circuits. This view has been reinforced by anatomical evidence showing dense axonal DA arbors throughout striatum, and a lattice network formed by DA axons and glutamatergic input from cortex and thalamus. Nonetheless, localized DA transients are seen in vivo using voltammetric methods with high spatial and temporal resolution. Mechanistic studies using similar methods in vitro have revealed local regulation of DA release by other transmitters and modulators, as well as by proteins known to be disrupted in Parkinson's disease and other movement disorders. Notably, the actions of most other striatal transmitters on DA release also do not conform to the synaptic doctrine, with the absence of direct synaptic contacts for glutamate, GABA, and acetylcholine (ACh) on striatal DA axons. Overall, the findings reviewed here indicate that DA signaling in the basal ganglia is sculpted by cooperation between the timing and pattern of DA input and those of local regulatory factors.
Collapse
Affiliation(s)
- M E Rice
- Department of Neurosurgery, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA.
| | | | | |
Collapse
|
39
|
Abstract
Neurotransmitter identity is a defining feature of all neurons because it constrains the type of information they convey, but many neurons release multiple transmitters. Although the physiological role for corelease has remained poorly understood, the vesicular uptake of one transmitter can regulate filling with the other by influencing expression of the H(+) electrochemical driving force. In addition, the sorting of vesicular neurotransmitter transporters and other synaptic vesicle proteins into different vesicle pools suggests the potential for distinct modes of release. Corelease thus serves multiple roles in synaptic transmission.
Collapse
Affiliation(s)
- Thomas S Hnasko
- Departments of Physiology & Neurology, University of California, San Francisco, California 94158-2517, USA.
| | | |
Collapse
|
40
|
Hua Z, Leal-Ortiz S, Foss SM, Waites CL, Garner CC, Voglmaier SM, Edwards RH. v-SNARE composition distinguishes synaptic vesicle pools. Neuron 2011; 71:474-87. [PMID: 21835344 DOI: 10.1016/j.neuron.2011.06.010] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/06/2011] [Indexed: 11/29/2022]
Abstract
Synaptic vesicles belong to two distinct pools, a recycling pool responsible for the evoked release of neurotransmitter and a resting pool unresponsive to stimulation. The uniform appearance of synaptic vesicles has suggested that differences in location or cytoskeletal association account for these differences in function. We now find that the v-SNARE tetanus toxin-insensitive vesicle-associated membrane protein (VAMP7) differs from other synaptic vesicle proteins in its distribution to the two pools, providing evidence that they differ in molecular composition. We also find that both resting and recycling pools undergo spontaneous release, and when activated by deletion of the longin domain, VAMP7 influences the properties of release. Further, the endocytosis that follows evoked and spontaneous release differs in mechanism, and specific sequences confer targeting to the different vesicle pools. The results suggest that different endocytic mechanisms generate synaptic vesicles with different proteins that can endow the vesicles with distinct properties.
Collapse
Affiliation(s)
- Zhaolin Hua
- Department of Neurology, University of California, San Francisco School of Medicine, San Francisco, CA 94143, USA
| | | | | | | | | | | | | |
Collapse
|
41
|
Cooper AP, Gillespie DC. Synaptotagmins I and II in the developing rat auditory brainstem: Synaptotagmin I is transiently expressed in glutamate-releasing immature inhibitory terminals. J Comp Neurol 2011; 519:2417-33. [DOI: 10.1002/cne.22634] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
42
|
Anantharam A, Bittner MA, Aikman RL, Stuenkel EL, Schmid SL, Axelrod D, Holz RW. A new role for the dynamin GTPase in the regulation of fusion pore expansion. Mol Biol Cell 2011; 22:1907-18. [PMID: 21460182 PMCID: PMC3103406 DOI: 10.1091/mbc.e11-02-0101] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The role of dynamin GTPase activity in controlling fusion pore expansion and postfusion granule membrane topology was investigated. The experiments show that, in addition to playing a role in endocytosis, GTPase activity of dynamin regulates the rapidity of fusion pore expansion from tens of milliseconds to seconds after fusion. Dynamin is a master regulator of membrane fission in endocytosis. However, a function for dynamin immediately upon fusion has also been suspected from a variety of experiments that measured release of granule contents. The role of dynamin guanosine triphosphate hydrolase (GTPase) activity in controlling fusion pore expansion and postfusion granule membrane topology was investigated using polarization optics and total internal reflection fluorescence microscopy (pTIRFM) and amperometry. A dynamin-1 (Dyn1) mutant with increased GTPase activity resulted in transient deformations consistent with rapid fusion pore widening after exocytosis; a Dyn1 mutant with decreased activity slowed fusion pore widening by stabilizing postfusion granule membrane deformations. The experiments indicate that, in addition to its role in endocytosis, GTPase activity of dynamin regulates the rapidity of fusion pore expansion from tens of milliseconds to seconds after fusion. These findings expand the membrane-sculpting repertoire of dynamin to include the regulation of immediate postfusion events in exocytosis that control the rate of release of soluble granule contents.
Collapse
Affiliation(s)
- Arun Anantharam
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA.
| | | | | | | | | | | | | |
Collapse
|
43
|
Asensio CS, Sirkis DW, Edwards RH. RNAi screen identifies a role for adaptor protein AP-3 in sorting to the regulated secretory pathway. ACTA ACUST UNITED AC 2011; 191:1173-87. [PMID: 21149569 PMCID: PMC3002028 DOI: 10.1083/jcb.201006131] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
AP-3 concentrates proteins within large dense-core vesicles to promote regulated exocytosis. The regulated release of proteins depends on their inclusion within large dense-core vesicles (LDCVs) capable of regulated exocytosis. LDCVs form at the trans-Golgi network (TGN), but the mechanism for protein sorting to this regulated secretory pathway (RSP) and the cytosolic machinery involved in this process have remained poorly understood. Using an RNA interference screen in Drosophila melanogaster S2 cells, we now identify a small number of genes, including several subunits of the heterotetrameric adaptor protein AP-3, which are required for sorting to the RSP. In mammalian neuroendocrine cells, loss of AP-3 dysregulates exocytosis due to a primary defect in LDCV formation. Previous work implicated AP-3 in the endocytic pathway, but we find that AP-3 promotes sorting to the RSP within the biosynthetic pathway at the level of the TGN. Although vesicles with a dense core still form in the absence of AP-3, they contain substantially less synaptotagmin 1, indicating that AP-3 concentrates the proteins required for regulated exocytosis.
Collapse
Affiliation(s)
- Cédric S Asensio
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | | | | |
Collapse
|