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Kim DI, Park S, Park S, Ye M, Chen JY, Kang SJ, Jhang J, Hunker AC, Zweifel LS, Caron KM, Vaughan JM, Saghatelian A, Palmiter RD, Han S. Presynaptic sensor and silencer of peptidergic transmission reveal neuropeptides as primary transmitters in pontine fear circuit. Cell 2024; 187:5102-5117.e16. [PMID: 39043179 PMCID: PMC11380597 DOI: 10.1016/j.cell.2024.06.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 11/17/2023] [Accepted: 06/25/2024] [Indexed: 07/25/2024]
Abstract
Neurons produce and release neuropeptides to communicate with one another. Despite their importance in brain function, circuit-based mechanisms of peptidergic transmission are poorly understood, primarily due to the lack of tools for monitoring and manipulating neuropeptide release in vivo. Here, we report the development of two genetically encoded tools for investigating peptidergic transmission in behaving mice: a genetically encoded large dense core vesicle (LDCV) sensor that detects presynaptic neuropeptide release and a genetically encoded silencer that specifically degrades neuropeptides inside LDCVs. Using these tools, we show that neuropeptides, not glutamate, encode the unconditioned stimulus in the parabrachial-to-amygdalar threat pathway during Pavlovian threat learning. We also show that neuropeptides play important roles in encoding positive valence and suppressing conditioned threat response in the amygdala-to-parabrachial endogenous opioidergic circuit. These results show that our sensor and silencer for presynaptic peptidergic transmission are reliable tools to investigate neuropeptidergic systems in awake, behaving animals.
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Affiliation(s)
- Dong-Il Kim
- Peptide Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Sekun Park
- Howard Hughes Medical Institute, Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Seahyung Park
- Peptide Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Mao Ye
- Peptide Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Jane Y Chen
- Howard Hughes Medical Institute, Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Sukjae J Kang
- Peptide Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Jinho Jhang
- Peptide Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Avery C Hunker
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Larry S Zweifel
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Kathleen M Caron
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Joan M Vaughan
- Peptide Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Alan Saghatelian
- Peptide Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Richard D Palmiter
- Howard Hughes Medical Institute, Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Sung Han
- Peptide Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA; Center for Neuroscience Imaging Research, Institute for Basic Science, Suwon 16419, Republic of Korea; Department of Biomedical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea.
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2
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Vaishampayan P, Lee Y. Redox-active vitamin C suppresses human osteosarcoma growth by triggering intracellular ROS-iron-calcium signaling crosstalk and mitochondrial dysfunction. Redox Biol 2024; 75:103288. [PMID: 39083898 PMCID: PMC11342202 DOI: 10.1016/j.redox.2024.103288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2024] [Accepted: 07/26/2024] [Indexed: 08/02/2024] Open
Abstract
Pharmacological vitamin C (VC) has gained attention for its pro-oxidant characteristics and selective ability to induce cancer cell death. However, defining its role in cancer has been challenging due to its complex redox properties. In this study, using a human osteosarcoma (OS) model, we show that the redox-active property of VC is critical for inducing non-apoptotic cancer cell death via intracellular reactive oxygen species (ROS)-iron-calcium crosstalk and mitochondrial dysfunction. In both 2D and 3D OS cell culture models, only the oxidizable form of VC demonstrated potent dose-dependent cytotoxicity, while non-oxidizable and oxidized VC derivatives had minimal effects. Live-cell imaging showed that only oxidizable VC caused a surge in cytotoxic ROS, dependent on iron rather than copper. Inhibitors of ferroptosis, a form of iron-dependent cell death, along with classical apoptosis inhibitors, were unable to completely counteract the cytotoxic effects induced by VC. Further pharmacological and genetic inhibition analyses showed that VC triggers calcium release through inositol 1,4,5-trisphosphate receptors (IP3Rs), leading to mitochondrial ROS production and eventual cell death. RNA sequencing revealed down-regulation of genes involved in the mitochondrial electron transport chain and oxidative phosphorylation upon pharmacological VC treatment. Consistently, high-dose VC reduced mitochondrial membrane potential, oxidative phosphorylation, and ATP levels, with ATP reconstitution rescuing VC-induced cytotoxicity. In vivo OS xenograft studies demonstrated reduced tumor growth with high-dose VC administration, concomitant with the altered expression of mitochondrial ATP synthase (MT-ATP). These findings emphasize VC's potential clinical utility in osteosarcoma treatment by inducing mitochondrial metabolic dysfunction through a vicious intracellular ROS-iron-calcium cycle.
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Affiliation(s)
- Prajakta Vaishampayan
- Department of Translational Medicine and Physiology, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA, 99202, USA
| | - Yool Lee
- Department of Translational Medicine and Physiology, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA, 99202, USA; Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, WA, 99164, USA; Sleep and Performance Research Center, Washington State University, Spokane, WA, 99202, USA; Steve Gleason Institute for Neuroscience, Washington State University, Spokane, WA, 99202, USA.
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3
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Sun X, Yazejian B, Peskoff A, Grinnell AD. Experimentally monitored calcium dynamics at synaptic active zones during neurotransmitter release in neuron-muscle cell cultures. Eur J Neurosci 2024; 59:2293-2319. [PMID: 38483240 DOI: 10.1111/ejn.16289] [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: 08/30/2023] [Revised: 01/04/2024] [Accepted: 02/01/2024] [Indexed: 05/08/2024]
Abstract
Ca2+-dependent K+ (BK) channels at varicosities in Xenopus nerve-muscle cell cultures were used to quantify experimentally the instantaneous active zone [Ca2+]AZ resulting from different rates and durations of Ca2+ entry in the absence of extrinsic buffers and correlate this with neurotransmitter release. Ca2+ tail currents produce mean peak [Ca2+]AZ ~ 30 μM; with continued influx, [Ca2+]AZ reaches ~45-60 μM at different rates depending on Ca2+ driving force and duration of influx. Both IBK and release are dependent on Ca2+ microdomains composed of both N- and L-type Ca channels. Domains collapse with a time constant of ~0.6 ms. We have constructed an active zone (AZ) model that approximately fits this data, and depends on incorporation of the high-capacity, low-affinity fixed buffer represented by phospholipid charges in the plasma membrane. Our observations suggest that in this preparation, (1) some BK channels, but few if any of the Ca2+ sensors that trigger release, are located within Ca2+ nanodomains while a large fraction of both are located far enough from Ca channels to be blockable by EGTA, (2) the IBK is more sensitive than the excitatory postsynaptic current (EPSC) to [Ca2+]AZ (K1/2-26 μM vs. ~36 μM [Ca2+]AZ); (3) with increasing [Ca2+]AZ, the IBK grows with a Hill coefficient of 2.5, the EPSC with a coefficient of 3.9; (4) release is dependent on the highest [Ca2+] achieved, independent of the time to reach it; (5) the varicosity synapses differ from mature frog nmjs in significant ways; and (6) BK channels are useful reporters of local [Ca2+]AZ.
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Affiliation(s)
- Xiaoping Sun
- Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Bruce Yazejian
- Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Arthur Peskoff
- Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Alan D Grinnell
- Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
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Hendricks EL, Liebl FLW. The CHD family chromatin remodeling enzyme, Kismet, promotes both clathrin-mediated and activity-dependent bulk endocytosis. PLoS One 2024; 19:e0300255. [PMID: 38512854 PMCID: PMC10956772 DOI: 10.1371/journal.pone.0300255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 02/23/2024] [Indexed: 03/23/2024] Open
Abstract
Chromodomain helicase DNA binding domain (CHD) proteins, including CHD7 and CHD8, remodel chromatin to enable transcriptional programs. Both proteins are important for proper neural development as heterozygous mutations in Chd7 and Chd8 are causative for CHARGE syndrome and correlated with autism spectrum disorders, respectively. Their roles in mature neurons are poorly understood despite influencing the expression of genes required for cell adhesion, neurotransmission, and synaptic plasticity. The Drosophila homolog of CHD7 and CHD8, Kismet (Kis), promotes neurotransmission, endocytosis, and larval locomotion. Endocytosis is essential in neurons for replenishing synaptic vesicles, maintaining protein localization, and preserving the size and composition of the presynaptic membrane. Several forms of endocytosis have been identified including clathrin-mediated endocytosis, which is coupled with neural activity and is the most prevalent form of synaptic endocytosis, and activity-dependent bulk endocytosis, which occurs during periods of intense stimulation. Kis modulates the expression of gene products involved in endocytosis including promoting shaggy/GSK3β expression while restricting PI3K92E. kis mutants electrophysiologically phenocopy a liquid facets mutant in response to paradigms that induce clathrin-mediated endocytosis and activity-dependent bulk endocytosis. Further, kis mutants do not show further reductions in endocytosis when activity-dependent bulk endocytosis or clathrin-mediated endocytosis are pharmacologically inhibited. We find that Kis is important in postsynaptic muscle for proper endocytosis but the ATPase domain of Kis is dispensable for endocytosis. Collectively, our data indicate that Kis promotes both clathrin-mediated endocytosis and activity-dependent bulk endocytosis possibly by promoting transcription of several endocytic genes and maintaining the size of the synaptic vesicle pool.
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Affiliation(s)
- Emily L. Hendricks
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, Illinois, United States of America
| | - Faith L. W. Liebl
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, Illinois, United States of America
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Pradeepan KS, McCready FP, Wei W, Khaki M, Zhang W, Salter MW, Ellis J, Martinez-Trujillo J. Calcium-Dependent Hyperexcitability in Human Stem Cell-Derived Rett Syndrome Neuronal Networks. BIOLOGICAL PSYCHIATRY GLOBAL OPEN SCIENCE 2024; 4:100290. [PMID: 38420187 PMCID: PMC10899066 DOI: 10.1016/j.bpsgos.2024.100290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 12/20/2023] [Accepted: 01/14/2024] [Indexed: 03/02/2024] Open
Abstract
Background Mutations in MECP2 predominantly cause Rett syndrome and can be modeled in vitro using human stem cell-derived neurons. Patients with Rett syndrome have signs of cortical hyperexcitability, such as seizures. Human stem cell-derived MECP2 null excitatory neurons have smaller soma size and reduced synaptic connectivity but are also hyperexcitable due to higher input resistance. Paradoxically, networks of MECP2 null neurons show a decrease in the frequency of network bursts consistent with a hypoconnectivity phenotype. Here, we examine this issue. Methods We reanalyzed multielectrode array data from 3 isogenic MECP2 cell line pairs recorded over 6 weeks (n = 144). We used a custom burst detection algorithm to analyze network events and isolated a phenomenon that we termed reverberating super bursts (RSBs). To probe potential mechanisms of RSBs, we conducted pharmacological manipulations using bicuculline, EGTA-AM, and DMSO on 1 cell line (n = 34). Results RSBs, often misidentified as single long-duration bursts, consisted of a large-amplitude initial burst followed by several high-frequency, low-amplitude minibursts. Our analysis revealed that MECP2 null networks exhibited increased frequency of RSBs, which produced increased bursts compared with isogenic controls. Bicuculline or DMSO treatment did not affect RSBs. EGTA-AM selectively eliminated RSBs and rescued network burst dynamics. Conclusions During early development, MECP2 null neurons are hyperexcitable and produce hyperexcitable networks. This may predispose them to the emergence of hypersynchronic states that potentially translate into seizures. Network hyperexcitability depends on asynchronous neurotransmitter release that is likely driven by presynaptic Ca2+ and can be rescued by EGTA-AM to restore typical network dynamics.
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Affiliation(s)
- Kartik S. Pradeepan
- Graduate Program in Neuroscience, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
- Robarts Research Institute, Western University, London, Ontario, Canada
| | - Fraser P. McCready
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- Developmental & Stem Cell Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Wei Wei
- Developmental & Stem Cell Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Milad Khaki
- Robarts Research Institute, Western University, London, Ontario, Canada
| | - Wenbo Zhang
- Neuroscience & Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Michael W. Salter
- Neuroscience & Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - James Ellis
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- Developmental & Stem Cell Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Julio Martinez-Trujillo
- Graduate Program in Neuroscience, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
- Robarts Research Institute, Western University, London, Ontario, Canada
- Western Institute for Neuroscience, Western University, London, Ontario, Canada
- Department of Physiology and Pharmacology, and Psychiatry, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
- Department of Psychiatry, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
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Sneyers F, Speelman-Rooms F, Verhelst SHL, Bootman MD, Bultynck G. Cellular effects of BAPTA: Are they only about Ca 2+ chelation? BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119589. [PMID: 37739271 DOI: 10.1016/j.bbamcr.2023.119589] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 09/06/2023] [Accepted: 09/10/2023] [Indexed: 09/24/2023]
Abstract
Intracellular Ca2+ signals play a vital role in a broad range of cell biological and physiological processes in all eukaryotic cell types. Dysregulation of Ca2+ signaling has been implicated in numerous human diseases. Over the past four decades, the understanding of how cells use Ca2+ as a messenger has flourished, largely because of the development of reporters that enable visualization of Ca2+ signals in different cellular compartments, and tools that can modulate cellular Ca2+ signaling. One such tool that is frequently used is BAPTA; a fast, high-affinity Ca2+-chelating molecule. By making use of a cell-permeable acetoxymethyl ester (AM) variant, BAPTA can be readily loaded into the cytosol of cells (referred to as BAPTAi), where it is trapped and able to buffer changes in cytosolic Ca2+. Due to the ease of loading of the AM version of BAPTA, this reagent has been used in hundreds of studies to probe the role of Ca2+ signaling in specific processes. As such, for decades, researchers have almost universally attributed changes in biological processes caused by BAPTAi to the involvement of Ca2+ signaling. However, BAPTAi has often been used without any form of control, and in many cases has neither been shown to be retained in cells for the duration of experiments nor to buffer any Ca2+ signals. Moreover, increasing evidence points to off-target cellular effects of BAPTA that are clearly not related to Ca2+ chelation. Here, we briefly introduce Ca2+ signaling and the history of Ca2+ chelators and fluorescent Ca2+ indicators. We highlight Ca2+-independent effects of BAPTAi on a broad range of molecular targets and describe some of BAPTAi's impacts on cell functions that occur independently of its Ca2+-chelating properties. Finally, we propose strategies for determining whether Ca2+ chelation, the binding of other metal ions, or off-target interactions with cell components are responsible for BAPTAi's effect on a particular process and suggest some future research directions.
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Affiliation(s)
- Flore Sneyers
- KU Leuven, Lab. Molecular & Cellular Signaling, Dep. Cellular & Molecular Medicine, Campus Gasthuisberg O/N-I bus 802, Herestraat 49, B-3000 Leuven, Belgium
| | - Femke Speelman-Rooms
- KU Leuven, Lab. Molecular & Cellular Signaling, Dep. Cellular & Molecular Medicine, Campus Gasthuisberg O/N-I bus 802, Herestraat 49, B-3000 Leuven, Belgium; KU Leuven, Department of Cellular and Molecular Medicine, Laboratory of Chemical Biology, Herestraat 49 box 901b, B-3000 Leuven, Belgium
| | - Steven H L Verhelst
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory of Chemical Biology, Herestraat 49 box 901b, B-3000 Leuven, Belgium
| | - Martin D Bootman
- The Open University, Cancer Research Group, School of Life, Health and Chemical Sciences, Milton Keynes, UK
| | - Geert Bultynck
- KU Leuven, Lab. Molecular & Cellular Signaling, Dep. Cellular & Molecular Medicine, Campus Gasthuisberg O/N-I bus 802, Herestraat 49, B-3000 Leuven, Belgium.
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He K, Han Y, Li X, Hernandez RX, Riboul DV, Feghhi T, Justs KA, Mahneva O, Perry S, Macleod GT, Dickman D. Physiologic and Nanoscale Distinctions Define Glutamatergic Synapses in Tonic vs Phasic Neurons. J Neurosci 2023; 43:4598-4611. [PMID: 37221096 PMCID: PMC10286941 DOI: 10.1523/jneurosci.0046-23.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 05/05/2023] [Accepted: 05/11/2023] [Indexed: 05/25/2023] Open
Abstract
Neurons exhibit a striking degree of functional diversity, each one tuned to the needs of the circuitry in which it is embedded. A fundamental functional dichotomy occurs in activity patterns, with some neurons firing at a relatively constant "tonic" rate, while others fire in bursts, a "phasic" pattern. Synapses formed by tonic versus phasic neurons are also functionally differentiated, yet the bases of their distinctive properties remain enigmatic. A major challenge toward illuminating the synaptic differences between tonic and phasic neurons is the difficulty in isolating their physiological properties. At the Drosophila neuromuscular junction, most muscle fibers are coinnervated by two motor neurons: the tonic "MN-Ib" and phasic "MN-Is." Here, we used selective expression of a newly developed botulinum neurotoxin transgene to silence tonic or phasic motor neurons in Drosophila larvae of either sex. This approach highlighted major differences in their neurotransmitter release properties, including probability, short-term plasticity, and vesicle pools. Furthermore, Ca2+ imaging demonstrated ∼2-fold greater Ca2+ influx at phasic neuron release sites relative to tonic, along with an enhanced synaptic vesicle coupling. Finally, confocal and super-resolution imaging revealed that phasic neuron release sites are organized in a more compact arrangement, with enhanced stoichiometry of voltage-gated Ca2+ channels relative to other active zone scaffolds. These data suggest that distinctions in active zone nano-architecture and Ca2+ influx collaborate to differentially tune glutamate release at tonic versus phasic synaptic subtypes.SIGNIFICANCE STATEMENT "Tonic" and "phasic" neuronal subtypes, based on differential firing properties, are common across many nervous systems. Using a recently developed approach to selectively silence transmission from one of these two neurons, we reveal specialized synaptic functional and structural properties that distinguish these specialized neurons. This study provides important insights into how input-specific synaptic diversity is achieved, which could have implications for neurologic disorders that involve changes in synaptic function.
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Affiliation(s)
- Kaikai He
- Department of Neurobiology, University of Southern California, Los Angeles, California 90089
- USC Neuroscience Graduate Program, Los Angeles, California 90089
| | - Yifu Han
- Department of Neurobiology, University of Southern California, Los Angeles, California 90089
- USC Neuroscience Graduate Program, Los Angeles, California 90089
| | - Xiling Li
- Department of Neurobiology, University of Southern California, Los Angeles, California 90089
- USC Neuroscience Graduate Program, Los Angeles, California 90089
| | - Roberto X Hernandez
- Integrative Biology and Neuroscience Graduate Program, Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida 33431
- International Max Planck Research School for Brain and Behavior, Jupiter, Florida 33458
| | - Danielle V Riboul
- Integrative Biology Graduate Program, Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida 33431
| | - Touhid Feghhi
- Department of Physics, Florida Atlantic University, Boca Raton, Florida 33431
| | - Karlis A Justs
- Integrative Biology and Neuroscience Graduate Program, Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida 33431
| | - Olena Mahneva
- Wilkes Honors College, Florida Atlantic University, Jupiter, Florida 33458
| | - Sarah Perry
- Department of Neurobiology, University of Southern California, Los Angeles, California 90089
| | - Gregory T Macleod
- Wilkes Honors College, Florida Atlantic University, Jupiter, Florida 33458
- Institute for Human Health and Disease Intervention, Florida Atlantic University, Jupiter, Florida 33458
| | - Dion Dickman
- Department of Neurobiology, University of Southern California, Los Angeles, California 90089
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Kim DI, Park S, Ye M, Chen JY, Jhang J, Hunker AC, Zweifel LS, Palmiter RD, Han S. Novel genetically encoded tools for imaging or silencing neuropeptide release from presynaptic terminals in vivo. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.19.524797. [PMID: 36712060 PMCID: PMC9882317 DOI: 10.1101/2023.01.19.524797] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Neurons produce and release neuropeptides to communicate with one another. Despite their profound impact on critical brain functions, circuit-based mechanisms of peptidergic transmission are poorly understood, primarily due to the lack of tools for monitoring and manipulating neuropeptide release in vivo. Here, we report the development of two genetically encoded tools for investigating peptidergic transmission in behaving mice: a genetically encoded large dense core vesicle (LDCV) sensor that detects the neuropeptides release presynaptically, and a genetically encoded silencer that specifically degrades neuropeptides inside the LDCV. Monitoring and silencing peptidergic and glutamatergic transmissions from presynaptic terminals using our newly developed tools and existing genetic tools, respectively, reveal that neuropeptides, not glutamate, are the primary transmitter in encoding unconditioned stimulus during Pavlovian threat learning. These results show that our sensor and silencer for peptidergic transmission are reliable tools to investigate neuropeptidergic systems in awake behaving animals.
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Affiliation(s)
- Dong-Il Kim
- Peptide Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Sekun Park
- Howard Hughes Medical Institute, Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Mao Ye
- Peptide Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Jane Y. Chen
- Howard Hughes Medical Institute, Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Jinho Jhang
- Peptide Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Avery C. Hunker
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Larry S. Zweifel
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Richard D. Palmiter
- Howard Hughes Medical Institute, Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Sung Han
- Peptide Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
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9
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Satake SI, Konishi S. Topographical distance between presynaptic Ca 2+ channels and exocytotic Ca 2+ sensors contributes to differential facilitatory actions of roscovitine on neurotransmitter release at cerebellar glutamatergic and GABAergic synapses. Eur J Neurosci 2021; 54:7048-7062. [PMID: 34622493 DOI: 10.1111/ejn.15487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 09/27/2021] [Accepted: 09/29/2021] [Indexed: 11/29/2022]
Abstract
Calcium influx into presynaptic terminals through voltage-gated Ca2+ channels triggers univesicular or multivesicular release of neurotransmitters depending on the characteristics of the release machinery. However, the mechanisms underlying multivesicular release (MVR) and its regulation remain unclear. Previous studies showed that in rat cerebellum, the cyclin-dependent kinase inhibitor roscovitine profoundly increases excitatory postsynaptic current (EPSC) amplitudes at granule cell (GC)-Purkinje cell (PC) synapses by enhancing the MVR of glutamate. This compound can also moderately augment the amplitude and prolong the decay time of inhibitory postsynaptic currents (IPSCs) at molecular layer interneuron (MLI)-PC synapses via MVR enhancement and GABA spillover, thus allowing for persistent activation of perisynaptic GABA receptors. The enhanced MVR may depend on the driving force for Cav 2.1 channel-mediated Ca2+ influx. To determine whether the distinct spatiotemporal dynamics of presynaptic Ca2+ influence MVR, we compared the effects of slow and fast Ca2+ chelators, that is, EGTA and BAPTA, respectively, on roscovitine-induced actions at GC-PC and MLI-PC synapses. Membrane-permeable EGTA-AM decreased GC-PC EPSC and MLI-PC IPSC amplitudes to a similar extent but suppressed the roscovitine-induced enhancement of EPSCs. In contrast, BAPTA-AM attenuated the effects of roscovitine on IPSCs. These results suggest that roscovitine augmented glutamate release by activating the release machinery located distally from the Cav 2.1 channel clusters, while it enhanced GABA release in a manner less dependent on those at distal sites. Therefore, the spatial relationships among Ca2+ channels, buffers, and sensors are critical determinants of the differential facilitatory actions of roscovitine on glutamatergic and GABAergic synapses in the cerebellar cortex.
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Affiliation(s)
- Shin' Ichiro Satake
- Brain Research Support Center, National Institute for Physiological Sciences (NIPS), Okazaki, Japan.,School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan
| | - Shiro Konishi
- Department of Neurophysiology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Japan
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