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Caputo M, Ivanova D, Chasserot-Golaz S, Doussau F, Haeberlé AM, Royer C, Ozkan S, Ecard J, Vitale N, Cousin MA, Tóth P, Gasman S, Ory S. Phospholipid Scramblase 1 Controls Efficient Neurotransmission and Synaptic Vesicle Retrieval at Cerebellar Synapses. J Neurosci 2024; 44:e0042242024. [PMID: 38839301 PMCID: PMC11223464 DOI: 10.1523/jneurosci.0042-24.2024] [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: 01/08/2024] [Revised: 04/23/2024] [Accepted: 04/28/2024] [Indexed: 06/07/2024] Open
Abstract
Phospholipids (PLs) are asymmetrically distributed at the plasma membrane. This asymmetric lipid distribution is transiently altered during calcium-regulated exocytosis, but the impact of this transient remodeling on presynaptic function is currently unknown. As phospholipid scramblase 1 (PLSCR1) randomizes PL distribution between the two leaflets of the plasma membrane in response to calcium activation, we set out to determine its role in neurotransmission. We report here that PLSCR1 is expressed in cerebellar granule cells (GrCs) and that PLSCR1-dependent phosphatidylserine egress occurred at synapses in response to neuron stimulation. Synaptic transmission is impaired at GrC Plscr1 -/- synapses, and both PS egress and synaptic vesicle (SV) endocytosis are inhibited in Plscr1 -/- cultured neurons from male and female mice, demonstrating that PLSCR1 controls PL asymmetry remodeling and SV retrieval following neurotransmitter release. Altogether, our data reveal a novel key role for PLSCR1 in SV recycling and provide the first evidence that PL scrambling at the plasma membrane is a prerequisite for optimal presynaptic performance.
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Affiliation(s)
- Margherita Caputo
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Daniela Ivanova
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
| | - Sylvette Chasserot-Golaz
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Frédéric Doussau
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Anne-Marie Haeberlé
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Cathy Royer
- Plateforme Imagerie In Vitro, Centre National de la Recherche Scientifique UPS3256, Strasbourg F-67000, France
| | - Sebahat Ozkan
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Jason Ecard
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Nicolas Vitale
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
| | - Petra Tóth
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Stéphane Gasman
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Stéphane Ory
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
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2
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Shaheen A, Richter Gorey CL, Sghaier A, Dason JS. Cholesterol is required for activity-dependent synaptic growth. J Cell Sci 2023; 136:jcs261563. [PMID: 37902091 DOI: 10.1242/jcs.261563] [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: 08/22/2023] [Accepted: 10/24/2023] [Indexed: 10/31/2023] Open
Abstract
Changes in cholesterol content of neuronal membranes occur during development and brain aging. Little is known about whether synaptic activity regulates cholesterol levels in neuronal membranes and whether these changes affect neuronal development and function. We generated transgenic flies that express the cholesterol-binding D4H domain of perfringolysin O toxin and found increased levels of cholesterol in presynaptic terminals of Drosophila larval neuromuscular junctions following increased synaptic activity. Reduced cholesterol impaired synaptic growth and largely prevented activity-dependent synaptic growth. Presynaptic knockdown of adenylyl cyclase phenocopied the impaired synaptic growth caused by reducing cholesterol. Furthermore, the effects of knocking down adenylyl cyclase and reducing cholesterol were not additive, suggesting that they function in the same pathway. Increasing cAMP levels using a dunce mutant with reduced phosphodiesterase activity failed to rescue this impaired synaptic growth, suggesting that cholesterol functions downstream of cAMP. We used a protein kinase A (PKA) sensor to show that reducing cholesterol levels reduced presynaptic PKA activity. Collectively, our results demonstrate that enhanced synaptic activity increased cholesterol levels in presynaptic terminals and that these changes likely activate the cAMP-PKA pathway during activity-dependent growth.
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Affiliation(s)
- Amber Shaheen
- Department of Biomedical Sciences, University of Windsor, Windsor, Ontario, N9B 3P4, Canada
| | - Claire L Richter Gorey
- Department of Biomedical Sciences, University of Windsor, Windsor, Ontario, N9B 3P4, Canada
| | - Adam Sghaier
- Department of Biomedical Sciences, University of Windsor, Windsor, Ontario, N9B 3P4, Canada
| | - Jeffrey S Dason
- Department of Biomedical Sciences, University of Windsor, Windsor, Ontario, N9B 3P4, Canada
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3
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Zakirjanova GF, Giniatullin AR, Gafurova CR, Malomouzh AI, Fedorov NS, Khaziev AN, Tsentsevitsky AN, Petrov AM. Effects of cholesterol oxidase on neurotransmission and acetylcholine levels at the mice neuromuscular junctions. Arch Biochem Biophys 2023; 749:109803. [PMID: 37955112 DOI: 10.1016/j.abb.2023.109803] [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: 07/17/2023] [Revised: 09/20/2023] [Accepted: 10/27/2023] [Indexed: 11/14/2023]
Abstract
Membrane cholesterol oxidation is a hallmark of redox and metabolic imbalance, and it may accompany neurodegenerative disorders. Using microelectrode recordings of postsynaptic responses as well as fluorescent dyes for monitoring synaptic vesicle cycling and membrane properties, the action of enzymatic cholesterol oxidation on neuromuscular transmission was studied in the mice diaphragms. Cholesterol oxidase (ChO) at low concentration disturbed lipid-ordering specifically in the synaptic membranes, but it did not change markedly spontaneous exocytosis and evoked release in response to single stimuli. At low external Ca2+ conditions, analysis of single exocytotic events revealed a decrease in minimal synaptic delay and the probability of exocytosis upon plasmalemmal cholesterol oxidation. At moderate- and high-frequency activity, ChO treatment enhanced both neurotransmitter and FM-dye release. Furthermore, it precluded a change in exocytotic mode from full-fusion to kiss-and-run during high-frequency stimulation. Accumulation of extracellular acetylcholine (without stimulation) dependent on vesamicol-sensitive transporters was suppressed by ChO. The effects of plasmalemmal cholesterol oxidation on both neurotransmitter/dye release at intense activity and external acetylcholine levels were reversed when synaptic vesicle membranes were also exposed to ChO (i.e., the enzyme treatment was combined with induction of exo-endocytotic cycling). Thus, we suggest that plasmalemmal cholesterol oxidation affects exocytotic machinery functioning, enhances synaptic vesicle recruitment to the exocytosis and decreases extracellular neurotransmitter levels at rest, whereas ChO acting on synaptic vesicle membranes suppresses the participation of the vesicles in the subsequent exocytosis and increases the neurotransmitter leakage. The mechanisms underlying ChO action can be related to the lipid raft disruption.
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Affiliation(s)
- Guzalia F Zakirjanova
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia; Kazan State Medical University, 49 Butlerova St., Kazan, 420012, RT, Russia
| | - Arthur R Giniatullin
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia; Kazan State Medical University, 49 Butlerova St., Kazan, 420012, RT, Russia
| | - Chulpan R Gafurova
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia; Kazan State Medical University, 49 Butlerova St., Kazan, 420012, RT, Russia
| | - Artem I Malomouzh
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia; Kazan National Research Technical University, 10, K. Marx Street, Kazan, 420111, Russia
| | - Nikita S Fedorov
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia
| | - Arthur N Khaziev
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia
| | - Andrei N Tsentsevitsky
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia
| | - Alexey M Petrov
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia; Kazan State Medical University, 49 Butlerova St., Kazan, 420012, RT, Russia; Kazan Federal University, 18 Kremlyovskaya Street, Kazan, 420008, Russia.
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Min JO, Ho HA, Lee W, Jung BC, Park SJ, Kim S, Lee SJ. Statins suppress cell-to-cell propagation of α-synuclein by lowering cholesterol. Cell Death Dis 2023; 14:474. [PMID: 37500624 PMCID: PMC10374525 DOI: 10.1038/s41419-023-05977-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 06/27/2023] [Accepted: 07/11/2023] [Indexed: 07/29/2023]
Abstract
Cell-to-cell propagation of protein aggregates has been implicated in the progression of neurodegenerative diseases. However, the underlying mechanism and modulators of this process are not fully understood. Here, we screened a small-molecule library in a search for agents that suppress the propagation of α-synuclein and mutant huntingtin (mHtt). These screens yielded several molecules, some of which were effective against both α-synuclein and mHtt. Among these molecules, we focused on simvastatin and pravastatin. Simvastatin administration in a transgenic model of synucleinopathy effectively ameliorated behavioral deficits and α-synuclein accumulation, whereas pravastatin had no effect. Because only simvastatin enters the brain effectively, these results suggest that inhibition of brain cholesterol synthesis is important in simvastatin effects. In cultured cells, accumulation of intracellular cholesterol, induced by genetic ablation of the NPC1 gene or by pharmacological treatment with U18666A, increased α-synuclein aggregation and secretion. In contrast, lowering cholesterol using methyl-β-cyclodextrin or statins reversed α-synuclein aggregation and secretion in NPC1-knockout cells. Consistent with these observations, feeding a high-fat diet aggravated α-synuclein pathology and behavioral deficits in the preformed fibril-injected mouse model, an effect that was also reversed by simvastatin administration. These results suggest that statins suppress propagation of protein aggregates by lowering cholesterol in the brain.
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Affiliation(s)
- Joo-Ok Min
- Department of Biomedical Sciences, Neuroscience Research Institute, Convergence Research Center for Dementia, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
| | - Hoang-Anh Ho
- Interdisciplinary Program in Neuroscience, College of Natural Sciences, Seoul National University, Seoul, Republic of Korea
| | - Wonjae Lee
- Department of Biomedical Sciences, Neuroscience Research Institute, Convergence Research Center for Dementia, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
- Neuramedy Co. Ltd, Seoul, Republic of Korea
| | - Byung Chul Jung
- Department of Biomedical Sciences, Neuroscience Research Institute, Convergence Research Center for Dementia, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
- Nutritional Sciences and Toxicology Department, University of California Berkeley, Berkeley, CA, USA
| | - Sung Jun Park
- Department of Biomedical Sciences, Neuroscience Research Institute, Convergence Research Center for Dementia, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
| | | | - Seung-Jae Lee
- Department of Biomedical Sciences, Neuroscience Research Institute, Convergence Research Center for Dementia, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea.
- Neuramedy Co. Ltd, Seoul, Republic of Korea.
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Kudryashova I. Presynaptic Plasticity Is Associated with Actin Polymerization. BIOCHEMISTRY (MOSCOW) 2023; 88:392-403. [PMID: 37076285 DOI: 10.1134/s0006297923030082] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
Modulation of presynaptic short-term plasticity induced by actin polymerization was studied in rat hippocampal slices using the paired-pulse paradigm. Schaffer collaterals were stimulated with paired pulses with a 70-ms interstimulus interval every 30 s before and during perfusion with jasplakinolide, an activator of actin polymerization. Jasplakinolide application resulted in the increase in the amplitudes of CA3-CA1 responses (potentiation) accompanied by a decrease in the paired-pulse facilitation, suggesting induction of presynaptic modifications. Jasplakinolide-induced potentiation depended on the initial paired-pulse rate. These data indicate that the jasplakinolide-mediated changes in actin polymerization increased the probability of neurotransmitter release. Less typical for CA3-CA1 synapses responses, such as a very low paired-pulse ratio (close to 1 or even lower) or even paired-pulse depression, were affected differently. Thus, jasplakinolide caused potentiation of the second, but not the first response to the paired stimulus, which increased the paired-pulse ratio from 0.8 to 1.0 on average, suggesting a negative impact of jasplakinolide on the mechanisms promoting paired-pulse depression. In general, actin polymerization facilitated potentiation, although the patterns of potentiation differed depending on the initial synapse characteristics. We conclude that in addition to the increase in the neurotransmitter release probability, jasplakinolide induced other actin polymerization-dependent mechanisms, including those involved in the paired-pulse depression.
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Affiliation(s)
- Irina Kudryashova
- Laboratory of Functional Biochemistry of the Nervous System, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, 119991, Russia.
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6
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Hendricks EL, Smith IR, Prates B, Barmaleki F, Liebl FLW. The CD63 homologs, Tsp42Ee and Tsp42Eg, restrict endocytosis and promote neurotransmission through differential regulation of synaptic vesicle pools. Front Cell Neurosci 2022; 16:957232. [PMID: 36072568 PMCID: PMC9441712 DOI: 10.3389/fncel.2022.957232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 08/04/2022] [Indexed: 11/30/2022] Open
Abstract
The Tetraspanin (Tsp), CD63, is a transmembrane component of late endosomes and facilitates vesicular trafficking through endosomal pathways. Despite being widely expressed in the human brain and localized to late endosomes, CD63's role in regulating endo- and exocytic cycling at the synapse has not been investigated. Synaptic vesicle pools are highly dynamic and disruptions in the mobilization and replenishment of these vesicle pools have adverse neuronal effects. We find that the CD63 homologs, Tsp42Ee and Tsp42Eg, are expressed at the Drosophila neuromuscular junction to regulate synaptic vesicle pools through both shared and unique mechanisms. Tsp42Ee and Tsp42Eg negatively regulate endocytosis and positively regulate neurotransmitter release. Both tsp mutants show impaired locomotion, reduced miniature endplate junctional current frequencies, and increased endocytosis. Expression of human CD63 in Drosophila neurons leads to impaired endocytosis suggesting the role of Tsps in endocytosis is conserved. We further show that Tsps influence the synaptic cytoskeleton and membrane composition by regulating Futsch loop formation and synaptic levels of SCAR and PI(4,5)P2. Finally, Tsp42Ee and Tsp42Eg influence the synaptic localization of several vesicle-associated proteins including Synapsin, Synaptotagmin, and Cysteine String Protein. Together, our results present a novel function for Tsps in the regulation of vesicle pools and provide insight into the molecular mechanisms of Tsp-related synaptic dysfunction.
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Affiliation(s)
| | | | | | | | - Faith L. W. Liebl
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL, United States
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7
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Chanaday NL, Kavalali ET. Role of the endoplasmic reticulum in synaptic transmission. Curr Opin Neurobiol 2022; 73:102538. [PMID: 35395547 PMCID: PMC9167765 DOI: 10.1016/j.conb.2022.102538] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 02/25/2022] [Accepted: 03/06/2022] [Indexed: 11/03/2022]
Abstract
Neurons possess a complex morphology spanning long distances and a large number of subcellular specializations such as presynaptic terminals and dendritic spines. This structural complexity is essential for maintenance of synaptic junctions and associated electrical as well as biochemical signaling events. Given the structural and functional complexity of neurons, neuronal endoplasmic reticulum is emerging as a key regulator of neuronal function, in particular synaptic signaling. Neuronal endoplasmic reticulum mediates calcium signaling, calcium and lipid homeostasis, vesicular trafficking, and proteostasis events that underlie autonomous functions of numerous subcellular compartments. However, based on its geometric complexity spanning the whole neuron, endoplasmic reticulum also integrates the activity of these autonomous compartments across the neuron and coordinates their interactions with the soma. In this article, we review recent work regarding neuronal endoplasmic reticulum function and its relationship to neurotransmission and plasticity.
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Affiliation(s)
- Natali L Chanaday
- Department of Pharmacology, School of Medicine, Vanderbilt University, Nashville, TN, 37240-7933, USA.
| | - Ege T Kavalali
- Department of Pharmacology, School of Medicine, Vanderbilt University, Nashville, TN, 37240-7933, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, 37240-7933, USA.
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8
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Mutants of the white ABCG Transporter in Drosophila melanogaster Have Deficient Olfactory Learning and Cholesterol Homeostasis. Int J Mol Sci 2021; 22:ijms222312967. [PMID: 34884779 PMCID: PMC8657504 DOI: 10.3390/ijms222312967] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 11/19/2021] [Accepted: 11/26/2021] [Indexed: 11/17/2022] Open
Abstract
Drosophila's white gene encodes an ATP-binding cassette G-subfamily (ABCG) half-transporter. White is closely related to mammalian ABCG family members that function in cholesterol efflux. Mutants of white have several behavioral phenotypes that are independent of visual defects. This study characterizes a novel defect of white mutants in the acquisition of olfactory memory using the aversive olfactory conditioning paradigm. The w1118 mutants learned slower than wildtype controls, yet with additional training, they reached wildtype levels of performance. The w1118 learning phenotype is also found in the wapricot and wcoral alleles, is dominant, and is rescued by genomic white and mini-white transgenes. Reducing dietary cholesterol strongly impaired olfactory learning for wildtype controls, while w1118 mutants were resistant to this deficit. The w1118 mutants displayed higher levels of cholesterol and cholesterol esters than wildtype under this low-cholesterol diet. Increasing levels of serotonin, dopamine, or both in the white mutants significantly improved w1118 learning. However, serotonin levels were not lower in the heads of the w1118 mutants than in wildtype controls. There were also no significant differences found in synapse numbers within the w1118 brain. We propose that the w1118 learning defect may be due to inefficient biogenic amine signaling brought about by altered cholesterol homeostasis.
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Kudryashova IV. The Reorganization of the Actin Matrix as a Factor of Presynaptic Plasticity. NEUROCHEM J+ 2021. [DOI: 10.1134/s1819712421030089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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10
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Dason JS, Sokolowski MB. A cGMP-dependent protein kinase, encoded by the Drosophila foraging gene, regulates neurotransmission through changes in synaptic structure and function. J Neurogenet 2021; 35:213-220. [PMID: 33998378 DOI: 10.1080/01677063.2021.1905639] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
A cGMP-dependent protein kinase (PKG) encoded by the Drosophila foraging (for) gene regulates both synaptic structure (nerve terminal growth) and function (neurotransmission) through independent mechanisms at the Drosophila larval neuromuscular junction (nmj). Glial for is known to restrict nerve terminal growth, whereas presynaptic for inhibits synaptic vesicle (SV) exocytosis during low frequency stimulation. Presynaptic for also facilitates SV endocytosis during high frequency stimulation. for's effects on neurotransmission can occur independent of any changes in nerve terminal growth. However, it remains unclear if for's effects on neurotransmission affect nerve terminal growth. Furthermore, it's possible that for's effects on synaptic structure contribute to changes in neurotransmission. In the present study, we examined these questions using RNA interference to selectively knockdown for in presynaptic neurons or glia at the Drosophila larval nmj. Consistent with our previous findings, presynaptic knockdown of for impaired SV endocytosis, whereas knockdown of glial for had no effect on SV endocytosis. Surprisingly, we found that knockdown of either presynaptic or glial for increased neurotransmitter release in response to low frequency stimulation. Knockdown of presynaptic for did not affect nerve terminal growth, demonstrating that for's effects on neurotransmission does not alter nerve terminal growth. In contrast, knockdown of glial for enhanced nerve terminal growth. This enhanced nerve terminal growth was likely the cause of the enhanced neurotransmitter release seen following knockdown of glial for. Overall, we show that for can affect neurotransmitter release by regulating both synaptic structure and function.
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Affiliation(s)
- Jeffrey S Dason
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada.,Department of Biomedical Sciences, University of Windsor, Windsor, Canada
| | - Marla B Sokolowski
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada.,Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Canada.,Child and Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, Canada
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11
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Iuliano M, Seeley C, Sapp E, Jones EL, Martin C, Li X, DiFiglia M, Kegel-Gleason KB. Disposition of Proteins and Lipids in Synaptic Membrane Compartments Is Altered in Q175/Q7 Huntington's Disease Mouse Striatum. Front Synaptic Neurosci 2021; 13:618391. [PMID: 33815086 PMCID: PMC8013775 DOI: 10.3389/fnsyn.2021.618391] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 02/24/2021] [Indexed: 12/14/2022] Open
Abstract
Dysfunction at synapses is thought to be an early change contributing to cognitive, psychiatric and motor disturbances in Huntington's disease (HD). In neurons, mutant Huntingtin collects in aggregates and distributes to the same sites as wild-type Huntingtin including on membranes and in synapses. In this study, we investigated the biochemical integrity of synapses in HD mouse striatum. We performed subcellular fractionation of striatal tissue from 2 and 6-month old knock-in Q175/Q7 HD and Q7/Q7 mice. Compared to striata of Q7/Q7 mice, proteins including GLUT3, Na+/K+ ATPase, NMDAR 2b, PSD95, and VGLUT1 had altered distribution in Q175/Q7 HD striata of 6-month old mice but not 2-month old mice. These proteins are found on plasma membranes and pre- and postsynaptic membranes supporting hypotheses that functional changes at synapses contribute to cognitive and behavioral symptoms of HD. Lipidomic analysis of mouse fractions indicated that compared to those of wild-type, fractions 1 and 2 of 6 months Q175/Q7 HD had altered levels of two species of PIP2, a phospholipid involved in synaptic signaling, increased levels of cholesterol ester and decreased cardiolipin species. At 2 months, increased levels of species of acylcarnitine, phosphatidic acid and sphingomyelin were measured. EM analysis showed that the contents of fractions 1 and 2 of Q7/Q7 and Q175/Q7 HD striata had a mix of isolated synaptic vesicles, vesicle filled axon terminals singly or in clusters, and ER and endosome-like membranes. However, those of Q175/Q7 striata contained significantly fewer and larger clumps of particles compared to those of Q7/Q7. Human HD postmortem putamen showed differences from control putamen in subcellular distribution of two proteins (Calnexin and GLUT3). Our biochemical, lipidomic and EM analysis show that the presence of the HD mutation conferred age dependent disruption of localization of synaptic proteins and lipids important for synaptic function. Our data demonstrate concrete biochemical changes suggesting altered integrity of synaptic compartments in HD mice that may mirror changes in HD patients and presage cognitive and psychiatric changes that occur in premanifest HD.
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12
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The vesicle cluster as a major organizer of synaptic composition in the short-term and long-term. Curr Opin Cell Biol 2021; 71:63-68. [PMID: 33706235 DOI: 10.1016/j.ceb.2021.02.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 01/22/2021] [Accepted: 02/04/2021] [Indexed: 01/29/2023]
Abstract
For decades, the synaptic vesicle cluster has been thought of as a storage space for synaptic vesicles, whose obvious function is to provide vesicles for the depolarization-induced release of neurotransmitters; however, reports over the last few years indicate that the synaptic vesicle cluster probably plays a much broader and more fundamental role in synaptic biology. Various experiments suggest that the cluster is able to regulate protein distribution and mobility in the synapse; moreover, it probably regulates cytoskeleton architecture, mediates the selective removal of synaptic components from the bouton, and controls the responses of the presynapse to plasticity. Here we discuss these features of the vesicle cluster and conclude that it serves as a key organizer of synaptic composition and dynamics.
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13
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Staurenghi E, Cerrato V, Gamba P, Testa G, Giannelli S, Leoni V, Caccia C, Buffo A, Noble W, Perez-Nievas BG, Leonarduzzi G. Oxysterols present in Alzheimer's disease brain induce synaptotoxicity by activating astrocytes: A major role for lipocalin-2. Redox Biol 2020; 39:101837. [PMID: 33360775 PMCID: PMC7772793 DOI: 10.1016/j.redox.2020.101837] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 12/14/2020] [Accepted: 12/14/2020] [Indexed: 01/19/2023] Open
Abstract
Among Alzheimer's disease (AD) brain hallmarks, the presence of reactive astrocytes was demonstrated to correlate with neuronal loss and cognitive deficits. Evidence indeed supports the role of reactive astrocytes as mediators of changes in neurons, including synapses. However, the complexity and the outcomes of astrocyte reactivity are far from being completely elucidated. Another key role in AD pathogenesis is played by alterations in brain cholesterol metabolism. Oxysterols (cholesterol oxidation products) are crucial for brain cholesterol homeostasis, and we previously demonstrated that changes in the brain levels of various oxysterols correlate with AD progression. Moreover, oxysterols have been shown to contribute to various pathological mechanisms involved in AD pathogenesis. In order to deepen the role of oxysterols in AD, we investigated whether they could contribute to astrocyte reactivity, and consequently impact on neuronal health. Results showed that oxysterols present in mild or severe AD brains induce a clear morphological change in mouse primary astrocytes, accompanied by the upregulation of some reactive astrocyte markers, including lipocalin-2 (Lcn2). Moreover, astrocyte conditioned media analysis revealed a significant increase in the release of Lcn2, cytokines, and chemokines in response to oxysterols. A significant reduction of postsynaptic density protein 95 (PSD95) and a concurrent increase in cleaved caspase-3 protein levels have been demonstrated in neurons co-cultured with oxysterol-treated astrocytes, pointing out that mediators released by astrocytes have an impact on neurons. Among these mediators, Lcn2 has been demonstrated to play a major role on synapses, affecting neurite morphology and decreasing dendritic spine density. These data demonstrated that oxysterols present in the AD brain promote astrocyte reactivity, determining the release of several mediators that affect neuronal health and synapses. Lcn2 has been shown to exert a key role in mediating the synaptotoxic effect of oxysterol-treated astrocytes.
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Affiliation(s)
- Erica Staurenghi
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, Turin, Italy.
| | - Valentina Cerrato
- Department of Neuroscience Rita Levi-Montalcini, University of Turin, Turin, Italy; Neuroscience Institute Cavalieri Ottolenghi, Orbassano, Turin, Italy
| | - Paola Gamba
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, Turin, Italy
| | - Gabriella Testa
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, Turin, Italy
| | - Serena Giannelli
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, Turin, Italy
| | - Valerio Leoni
- Department of Medicine and Surgery, University of Milan-Bicocca, Desio, Monza-Brianza (MB), Italy
| | - Claudio Caccia
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Annalisa Buffo
- Department of Neuroscience Rita Levi-Montalcini, University of Turin, Turin, Italy; Neuroscience Institute Cavalieri Ottolenghi, Orbassano, Turin, Italy
| | - Wendy Noble
- Institute of Psychiatry, Psychology and Neuroscience, Department of Basic and Clinical Neuroscience, King's College London, London, UK
| | - Beatriz Gomez Perez-Nievas
- Institute of Psychiatry, Psychology and Neuroscience, Department of Basic and Clinical Neuroscience, King's College London, London, UK
| | - Gabriella Leonarduzzi
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, Turin, Italy
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14
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Shirokova OM, Pchelin PV, Mukhina IV. MERCs. The Novel Assistant to Neurotransmission? Front Neurosci 2020; 14:589319. [PMID: 33240039 PMCID: PMC7680918 DOI: 10.3389/fnins.2020.589319] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 10/19/2020] [Indexed: 12/11/2022] Open
Abstract
In neuroscience, much attention is paid to intercellular interactions, in particular, to synapses. However, many researchers do not pay due attention to the contribution of intracellular contacts to the work of intercellular interactions. Nevertheless, along with synapses, intracellular contacts also have complex organization and a tremendous number of regulatory elements. Mitochondria-endoplasmic reticulum contacts (MERCs) are a specific site of interaction between the two organelles; they provide a basis for a large number of cellular functions, such as calcium homeostasis, lipid metabolism, autophagy, and apoptosis. Despite the presence of these contacts in various parts of neurons and glial cells, it is yet not known whether they fulfill the same functions. There are still many unsolved questions about the work of these intracellular contacts, and one of the most important among them is if MERCs, with their broad implication into synaptic events, can be considered the assistant to neurotransmission?
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Affiliation(s)
- Olesya M Shirokova
- Central Scientific Research Laboratory, Institute of Fundamental Medicine, Privolzhsky Research Medical University, Nizhny Novgorod, Russia
| | - Pavel V Pchelin
- Central Scientific Research Laboratory, Institute of Fundamental Medicine, Privolzhsky Research Medical University, Nizhny Novgorod, Russia.,Department of Neurotechnology, Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia
| | - Irina V Mukhina
- Central Scientific Research Laboratory, Institute of Fundamental Medicine, Privolzhsky Research Medical University, Nizhny Novgorod, Russia.,Department of Neurotechnology, Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia
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15
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Merezhko M, Uronen RL, Huttunen HJ. The Cell Biology of Tau Secretion. Front Mol Neurosci 2020; 13:569818. [PMID: 33071756 PMCID: PMC7539664 DOI: 10.3389/fnmol.2020.569818] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 08/26/2020] [Indexed: 12/27/2022] Open
Abstract
The progressive accumulation and spread of misfolded tau protein in the nervous system is the hallmark of tauopathies, progressive neurodegenerative diseases with only symptomatic treatments available. A growing body of evidence suggests that spreading of tau pathology can occur via cell-to-cell transfer involving secretion and internalization of pathological forms of tau protein followed by templated misfolding of normal tau in recipient cells. Several studies have addressed the cell biological mechanisms of tau secretion. It now appears that instead of a single mechanism, cells can secrete tau via three coexisting pathways: (1) translocation through the plasma membrane; (2) membranous organelles-based secretion; and (3) ectosomal shedding. The relative importance of these pathways in the secretion of normal and pathological tau is still elusive, though. Moreover, glial cells contribute to tau propagation, and the involvement of different cell types, as well as different secretion pathways, complicates the understanding of prion-like propagation of tauopathy. One of the important regulators of tau secretion in neuronal activity, but its mechanistic connection to tau secretion remains unclear and may involve all three secretion pathways of tau. This review article summarizes recent advancements in the field of tau secretion with an emphasis on cell biological aspects of the secretion process and discusses the role of neuronal activity and glial cells in the spread of pathological forms of tau.
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Affiliation(s)
- Maria Merezhko
- Neuroscience Center, HiLIFE, University of Helsinki, Helsinki, Finland
| | | | - Henri J Huttunen
- Neuroscience Center, HiLIFE, University of Helsinki, Helsinki, Finland
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16
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Korinek M, Gonzalez-Gonzalez IM, Smejkalova T, Hajdukovic D, Skrenkova K, Krusek J, Horak M, Vyklicky L. Cholesterol modulates presynaptic and postsynaptic properties of excitatory synaptic transmission. Sci Rep 2020; 10:12651. [PMID: 32724221 PMCID: PMC7387334 DOI: 10.1038/s41598-020-69454-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 07/10/2020] [Indexed: 12/22/2022] Open
Abstract
Cholesterol is a structural component of cellular membranes particularly enriched in synapses but its role in synaptic transmission remains poorly understood. We used rat hippocampal cultures and their acute cholesterol depletion by methyl-β-cyclodextrin as a tool to describe the physiological role of cholesterol in glutamatergic synaptic transmission. Cholesterol proved to be a key molecule for the function of synapses as its depletion resulted in a significant reduction of both NMDA receptor (NMDAR) and AMPA/kainate receptor-mediated evoked excitatory postsynaptic currents (eEPSCs), by 94% and 72%, respectively. We identified two presynaptic and two postsynaptic steps of synaptic transmission which are modulated by cholesterol and explain together the above-mentioned reduction of eEPSCs. In the postsynapse, we show that physiological levels of cholesterol are important for maintaining the normal probability of opening of NMDARs and for keeping NMDARs localized in synapses. In the presynapse, our results favour the hypothesis of a role of cholesterol in the propagation of axonal action potentials. Finally, cholesterol is a negative modulator of spontaneous presynaptic glutamate release. Our study identifies cholesterol as an important endogenous regulator of synaptic transmission and provides insight into molecular mechanisms underlying the neurological manifestation of diseases associated with impaired cholesterol synthesis or decomposition.
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Affiliation(s)
- Miloslav Korinek
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic.
| | | | - Tereza Smejkalova
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic
| | - Dragana Hajdukovic
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic
| | - Kristyna Skrenkova
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic
| | - Jan Krusek
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic
| | - Martin Horak
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic
| | - Ladislav Vyklicky
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic
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17
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Bradley RP, Slochower DR, Janmey PA, Radhakrishnan R. Divalent cations bind to phosphoinositides to induce ion and isomer specific propensities for nano-cluster initiation in bilayer membranes. ROYAL SOCIETY OPEN SCIENCE 2020; 7:192208. [PMID: 32537210 PMCID: PMC7277276 DOI: 10.1098/rsos.192208] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 04/14/2020] [Indexed: 05/22/2023]
Abstract
We report all-atom molecular dynamics simulations of asymmetric bilayers containing phosphoinositides in the presence of monovalent and divalent cations. We have characterized the molecular mechanism by which these divalent cations interact with phosphoinositides. Ca2+ desolvates more readily, consistent with single-molecule calculations, and forms a network of ionic-like bonds that serve as a 'molecular glue' that allows a single ion to coordinate with up to three phosphatidylinositol-(4,5)-bisphosphate (PI(4, 5)P2) lipids. The phosphatidylinositol-(3,5)-bisphosphate isomer shows no such effect and neither does PI(4, 5)P2 in the presence of Mg2+. The resulting network of Ca2+-mediated lipid-lipid bonds grows to span the entire simulation space and therefore has implications for the lateral distribution of phosophoinositides in the bilayer. We observe context-specific differences in lipid diffusion rates, lipid surface densities and bilayer structure. The molecular-scale delineation of ion-lipid arrangements reported here provides insight into similar nanocluster formation induced by peripheral proteins to regulate the formation of functional signalling complexes on the membrane.
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Affiliation(s)
- Ryan P. Bradley
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - David R. Slochower
- Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Paul A. Janmey
- Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ravi Radhakrishnan
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
- Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
- Author for correspondence: Ravi Radhakrishnan e-mail:
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18
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Sanyour HJ, Li N, Rickel AP, Torres HM, Anderson RH, Miles MR, Childs JD, Francis KR, Tao J, Hong Z. Statin-mediated cholesterol depletion exerts coordinated effects on the alterations in rat vascular smooth muscle cell biomechanics and migration. J Physiol 2020; 598:1505-1522. [PMID: 32083311 DOI: 10.1113/jp279528] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 02/18/2020] [Indexed: 12/28/2022] Open
Abstract
KEY POINTS This study demonstrates and evaluates the changes in rat vascular smooth muscle cell biomechanics following statin-mediated cholesterol depletion. Evidence is presented to show correlated changes in migration and adhesion of vascular smooth muscle cells to extracellular matrix proteins fibronectin and collagen. Concurrently, integrin α5 expression was enhanced but not integrin α2. Atomic force microscopy analysis provides compelling evidence of coordinated reduction in vascular smooth muscle cell stiffness and actin cytoskeletal orientation in response to statin-mediated cholesterol depletion. Proof is provided that statin-mediated cholesterol depletion remodels total vascular smooth muscle cell cytoskeletal orientation that may additionally participate in altering ex vivo aortic vessel function. It is concluded that statin-mediated cholesterol depletion may coordinate vascular smooth muscle cell migration and adhesion to different extracellular matrix proteins and regulate cellular stiffness and cytoskeletal orientation, thus impacting the biomechanics of the cell. ABSTRACT Not only does cholesterol induce an inflammatory response and deposits in foam cells at the atherosclerotic plaque, it also regulates cellular mechanics, proliferation and migration in atherosclerosis progression. Statins are HMG-CoA reductase inhibitors that are known to inhibit cellular cholesterol biosynthesis and are clinically prescribed to patients with hypercholesterolemia or related cardiovascular conditions. Nonetheless, the effect of statin-mediated cholesterol management on cellular biomechanics is not fully understood. In this study, we aimed to assess the effect of fluvastatin-mediated cholesterol management on primary rat vascular smooth muscle cell (VSMC) biomechanics. Real-time measurement of cell adhesion, stiffness, and imaging were performed using atomic force microscopy (AFM). Cellular migration on extra cellular matrix (ECM) protein surfaces was studied by time-lapse imaging. The effect of changes in VSMC biomechanics on aortic function was assessed using an ex vivo myograph system. Fluvastatin-mediated cholesterol depletion (-27.8%) lowered VSMC migration distance on a fibronectin (FN)-coated surface (-14.8%) but not on a type 1 collagen (COL1)-coated surface. VSMC adhesion force to FN (+33%) and integrin α5 expression were enhanced but COL1 adhesion and integrin α2 expression were unchanged upon cholesterol depletion. In addition, VSMC stiffness (-46.6%) and ex vivo aortic ring contraction force (-40.1%) were lowered and VSMC actin cytoskeletal orientation was reduced (-24.5%) following statin-mediated cholesterol depletion. Altogether, it is concluded that statin-mediated cholesterol depletion may coordinate VSMC migration and adhesion to different ECM proteins and regulate cellular stiffness and cytoskeletal orientation, thus impacting the biomechanics of the cell and aortic function.
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Affiliation(s)
- Hanna J Sanyour
- Department of Biomedical Engineering, University of South Dakota, Sioux Falls, SD, 57107, USA.,BioSNTR, Sioux Falls, SD, 57107, USA
| | - Na Li
- Department of Biomedical Engineering, University of South Dakota, Sioux Falls, SD, 57107, USA.,BioSNTR, Sioux Falls, SD, 57107, USA
| | - Alex P Rickel
- Department of Biomedical Engineering, University of South Dakota, Sioux Falls, SD, 57107, USA.,BioSNTR, Sioux Falls, SD, 57107, USA
| | - Haydee M Torres
- Cancer Biology and Immunotherapies Group, Sanford Research, Sioux Falls, SD, 57104, USA.,Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD, 57007, USA
| | - Ruthellen H Anderson
- Cellular Therapies and Stem Cell Biology Group, Sanford Research, Sioux Falls, SD, 57104, USA.,Department of Pediatrics, Sanford School of Medicine, University of South Dakota, Vermillion, SD, 57069, USA
| | - Miranda R Miles
- BioSNTR, Sioux Falls, SD, 57107, USA.,Mechanical Engineering Department, South Dakota State University, Brookings, SD, 57007, USA
| | - Josh D Childs
- Department of Biomedical Engineering, University of South Dakota, Sioux Falls, SD, 57107, USA.,BioSNTR, Sioux Falls, SD, 57107, USA
| | - Kevin R Francis
- Department of Biomedical Engineering, University of South Dakota, Sioux Falls, SD, 57107, USA.,Cellular Therapies and Stem Cell Biology Group, Sanford Research, Sioux Falls, SD, 57104, USA.,Department of Pediatrics, Sanford School of Medicine, University of South Dakota, Vermillion, SD, 57069, USA
| | - Jianning Tao
- Department of Biomedical Engineering, University of South Dakota, Sioux Falls, SD, 57107, USA.,Cancer Biology and Immunotherapies Group, Sanford Research, Sioux Falls, SD, 57104, USA.,Department of Pediatrics, Sanford School of Medicine, University of South Dakota, Vermillion, SD, 57069, USA.,Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD, 57007, USA
| | - Zhongkui Hong
- Department of Biomedical Engineering, University of South Dakota, Sioux Falls, SD, 57107, USA.,BioSNTR, Sioux Falls, SD, 57107, USA
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19
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DelBove CE, Strothman CE, Lazarenko RM, Huang H, Sanders CR, Zhang Q. Reciprocal modulation between amyloid precursor protein and synaptic membrane cholesterol revealed by live cell imaging. Neurobiol Dis 2019; 127:449-461. [PMID: 30885793 PMCID: PMC6588454 DOI: 10.1016/j.nbd.2019.03.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 02/03/2019] [Accepted: 03/12/2019] [Indexed: 12/20/2022] Open
Abstract
The amyloid precursor protein (APP) has been extensively studied because of its association with Alzheimer's disease (AD). However, APP distribution across different subcellular membrane compartments and its function in neurons remains unclear. We generated an APP fusion protein with a pH-sensitive green fluorescent protein at its ectodomain and a pH-insensitive blue fluorescent protein at its cytosolic domain and used it to measure APP's distribution, subcellular trafficking, and cleavage in live neurons. This reporter, closely resembling endogenous APP, revealed only a limited correlation between synaptic activities and APP trafficking. However, the synaptic surface fraction of APP was increased by a reduction in membrane cholesterol levels, a phenomenon that involves APP's cholesterol-binding motif. Mutations at or near binding sites not only reduced both the surface fraction of APP and membrane cholesterol levels in a dominant negative manner, but also increased synaptic vulnerability to moderate membrane cholesterol reduction. Our results reveal reciprocal modulation of APP and membrane cholesterol levels at synaptic boutons.
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Affiliation(s)
- Claire E DelBove
- Department of Pharmacology, Vanderbilt University, United States of America
| | - Claire E Strothman
- Department of Cell and Developmental Biology, Vanderbilt University, United States of America
| | - Roman M Lazarenko
- Department of Pharmacology, Vanderbilt University, United States of America
| | - Hui Huang
- Department of Biochemistry, Vanderbilt University, United States of America
| | - Charles R Sanders
- Department of Biochemistry, Vanderbilt University, United States of America; Department of Medicine, Vanderbilt University Medical Center, United States of America
| | - Qi Zhang
- Department of Pharmacology, Vanderbilt University, United States of America; Brain Institute, Florida Atlantic University, United States of America.
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20
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Drosophila melanogaster foraging regulates a nociceptive-like escape behavior through a developmentally plastic sensory circuit. Proc Natl Acad Sci U S A 2019; 117:23286-23291. [PMID: 31213548 DOI: 10.1073/pnas.1820840116] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Painful or threatening experiences trigger escape responses that are guided by nociceptive neuronal circuitry. Although some components of this circuitry are known and conserved across animals, how this circuitry is regulated at the genetic and developmental levels is mostly unknown. To escape noxious stimuli, such as parasitoid wasp attacks, Drosophila melanogaster larvae generate a curling and rolling response. Rover and sitter allelic variants of the Drosophila foraging (for) gene differ in parasitoid wasp susceptibility, suggesting a link between for and nociception. By optogenetically activating cells associated with each of for's promoters (pr1-pr4), we show that pr1 cells regulate larval escape behavior. In accordance with rover and sitter differences in parasitoid wasp susceptibility, we found that rovers have higher pr1 expression and increased sensitivity to nociception relative to sitters. The for null mutants display impaired responses to thermal nociception, which are rescued by restoring for expression in pr1 cells. Conversely, knockdown of for in pr1 cells phenocopies the for null mutant. To gain insight into the circuitry underlying this response, we used an intersectional approach and activity-dependent GFP reconstitution across synaptic partners (GRASP) to show that pr1 cells in the ventral nerve cord (VNC) are required for the nociceptive response, and that multidendritic sensory nociceptive neurons synapse onto pr1 neurons in the VNC. Finally, we show that activation of the pr1 circuit during development suppresses the escape response. Our data demonstrate a role of for in larval nociceptive behavior. This function is specific to for pr1 neurons in the VNC, guiding a developmentally plastic escape response circuit.
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21
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Dopamine Burden Triggers Cholesterol Overload Following Disruption of Synaptogenesis in Minimal Hepatic Encephalopathy. Neuroscience 2019; 410:1-15. [PMID: 31078686 DOI: 10.1016/j.neuroscience.2019.04.056] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 04/27/2019] [Accepted: 04/30/2019] [Indexed: 01/05/2023]
Abstract
The contribution of Dopamine (DA) to minimal hepatic encephalopathy (MHE) has been demonstrated. However, recent studies have revealed that cholesterol (CHO) treatment substantially increased the risk of dementia. The objectives of this study were to investigate whether CHO was induced by DA overload and its involvement in DA-induced cognitive impairment in MHE. Our study showed that DA treatment triggered CHO biosynthesis via the activation of JNK3/SREBP2 signaling pathway in primary cultured astrocytes. Conditioned media from DA-treated astrocytes increased CHO uptake by primary cultured neurons and disrupted synaptic formations; at the same time, inhibition of CHO synthesis and transportation from astrocytes diminished the disruption of synaptogenesis, which indicates the involvement of CHO in the perturbation of neural synaptogenesis in vitro. Secondary secretion of DA from primary cultured neurons was stimulated by CHO secreted from astrocytes. DA induced synergistic decreases of PPARγ/pERK/pCREB expressions in the presence of CHO in neurons, leading to synergistic synaptic impairment. Memory impairments were observed in MHE/DA-treated rats, which were partially rescued by atorvastatin (ATVS) treatment, confirming the involvement of CHO burden in vivo. Overall, our study suggests that DA overload triggers obvious CHO production from astrocytes. Excessive CHO in turn triggered neurons to secrete abundant DA and DA burden in combination with CHO overload elicit the cognitive decline and memory loss via PPARγ/ERK/CREB pathway in MHE.
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22
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Cholesterol and the Safety Factor for Neuromuscular Transmission. Int J Mol Sci 2019; 20:ijms20051046. [PMID: 30823359 PMCID: PMC6429197 DOI: 10.3390/ijms20051046] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 02/23/2019] [Accepted: 02/24/2019] [Indexed: 12/12/2022] Open
Abstract
A present review is devoted to the analysis of literature data and results of own research. Skeletal muscle neuromuscular junction is specialized to trigger the striated muscle fiber contraction in response to motor neuron activity. The safety factor at the neuromuscular junction strongly depends on a variety of pre- and postsynaptic factors. The review focuses on the crucial role of membrane cholesterol to maintain a high efficiency of neuromuscular transmission. Cholesterol metabolism in the neuromuscular junction, its role in the synaptic vesicle cycle and neurotransmitter release, endplate electrogenesis, as well as contribution of cholesterol to the synaptogenesis, synaptic integrity, and motor disorders are discussed.
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23
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Dason JS, Allen AM, Vasquez OE, Sokolowski MB. Distinct functions of a cGMP-dependent protein kinase in nerve terminal growth and synaptic vesicle cycling. J Cell Sci 2019; 132:jcs.227165. [DOI: 10.1242/jcs.227165] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 02/26/2019] [Indexed: 01/20/2023] Open
Abstract
Sustained neurotransmission requires the tight coupling of synaptic vesicle (SV) exocytosis and endocytosis. The mechanisms underlying this coupling are poorly understood. We tested the hypothesis that a cGMP-dependent protein kinase (PKG), encoded by the foraging (for) gene in Drosophila melanogaster, is critical for this process using a for null mutant, genomic rescues, and tissue specific rescues. We uncoupled FOR's exocytic and endocytic functions in neurotransmission using a temperature-sensitive shibire mutant in conjunction with fluorescein-assisted light inactivation of FOR. We discovered a dual role for presynaptic FOR, where FOR inhibits SV exocytosis during low frequency stimulation by negatively regulating presynaptic Ca2+ levels and maintains neurotransmission during high frequency stimulation by facilitating SV endocytosis. Additionally, glial FOR negatively regulated nerve terminal growth through TGF-β signaling and this developmental effect was independent from FOR's effects on neurotransmission. Overall, FOR plays a critical role in coupling SV exocytosis and endocytosis, thereby balancing these two components to maintain sustained neurotransmission.
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Affiliation(s)
- Jeffrey S. Dason
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada
- Department of Biological Sciences, University of Windsor, Windsor, Ontario, N9B 3P4, Canada
| | - Aaron M. Allen
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada
- Present Address: Centre for Neural Circuits and Behaviour, University of Oxford, OX1 3SR Oxford, UK
| | - Oscar E. Vasquez
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada
| | - Marla B. Sokolowski
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada
- Child and Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario, M5G 1M1, Canada
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24
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Cantarutti KC, Burgess J, Brill JA, Dason JS. Type II phosphatidylinositol 4-kinase regulates nerve terminal growth and synaptic vesicle recycling. J Neurogenet 2018; 32:230-235. [DOI: 10.1080/01677063.2018.1502762] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
| | - Jason Burgess
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Julie A. Brill
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
- Institute of Medical Science, University of Toronto, Toronto, Canada
| | - Jeffrey S. Dason
- Department of Biological Sciences, University of Windsor, Windsor, Canada
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25
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Rabenstein M, Peter F, Joost S, Trilck M, Rolfs A, Frech MJ. Decreased calcium flux in Niemann-Pick type C1 patient-specific iPSC-derived neurons due to higher amount of calcium-impermeable AMPA receptors. Mol Cell Neurosci 2017; 83:27-36. [PMID: 28666962 DOI: 10.1016/j.mcn.2017.06.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 06/08/2017] [Accepted: 06/25/2017] [Indexed: 01/31/2023] Open
Abstract
Niemann-Pick disease type C1 (NPC1) is a rare progressive neurodegenerative disorder caused by mutations in the NPC1 gene, resulting mainly in the accumulation of cholesterol and the ganglioside GM2. Recently, we described accumulations of these lipids in neuronal differentiated cells derived from NPC1 patient-specific induced pluripotent stem cells (iPSCs). As these lipids are essential for proper cell membrane composition, we were interested in the expression and function of voltage-gated ion channels and excitatory AMPA receptors (AMPARs) in neurons derived from three patient-specific iPSC lines. By means of patch clamp recordings and microfluorimetric measurements of calcium (Ca2+), we examined the expression of voltage-gated ion channels and AMPARs. Cells of the three used cell lines carrying the c.1836A>C/c.1628delC, the c.1180T>C or the c.3182T>C mutation demonstrated a significantly reduced AMPA-induced Ca2+-influx, suggesting an altered expression profile of these receptors. RT-qPCR revealed a significant upregulation of mRNA for the AMPA receptor subunits GluA1 and GluA2 and western blot analysis showed increased protein level of GluA2. Thus, we conclude that the observed reduced Ca2+-influx is based on an increase of GluA2 containing Ca2+-impermeable AMPARs. An attenuated function of GluRs in neurons potentially contributes to the progressive neurodegeneration observed in NPC1 and might represent an objective in regard of the development of new therapeutic approaches in NPC1.
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Affiliation(s)
- Michael Rabenstein
- Albrecht-Kossel-Institute for Neuroregeneration (AKos), University Medicine Rostock, Gehlsheimer Straße 20, D-18147 Rostock, Germany.
| | - Franziska Peter
- Albrecht-Kossel-Institute for Neuroregeneration (AKos), University Medicine Rostock, Gehlsheimer Straße 20, D-18147 Rostock, Germany.
| | - Sarah Joost
- Albrecht-Kossel-Institute for Neuroregeneration (AKos), University Medicine Rostock, Gehlsheimer Straße 20, D-18147 Rostock, Germany.
| | - Michaela Trilck
- Albrecht-Kossel-Institute for Neuroregeneration (AKos), University Medicine Rostock, Gehlsheimer Straße 20, D-18147 Rostock, Germany.
| | - Arndt Rolfs
- Albrecht-Kossel-Institute for Neuroregeneration (AKos), University Medicine Rostock, Gehlsheimer Straße 20, D-18147 Rostock, Germany.
| | - Moritz J Frech
- Albrecht-Kossel-Institute for Neuroregeneration (AKos), University Medicine Rostock, Gehlsheimer Straße 20, D-18147 Rostock, Germany.
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26
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Valenza M, Chen JY, Di Paolo E, Ruozi B, Belletti D, Ferrari Bardile C, Leoni V, Caccia C, Brilli E, Di Donato S, Boido MM, Vercelli A, Vandelli MA, Forni F, Cepeda C, Levine MS, Tosi G, Cattaneo E. Cholesterol-loaded nanoparticles ameliorate synaptic and cognitive function in Huntington's disease mice. EMBO Mol Med 2016; 7:1547-64. [PMID: 26589247 PMCID: PMC4693506 DOI: 10.15252/emmm.201505413] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Brain cholesterol biosynthesis and cholesterol levels are reduced in mouse models of Huntington's disease (HD), suggesting that locally synthesized, newly formed cholesterol is less available to neurons. This may be detrimental for neuronal function, especially given that locally synthesized cholesterol is implicated in synapse integrity and remodeling. Here, we used biodegradable and biocompatible polymeric nanoparticles (NPs) modified with glycopeptides (g7) and loaded with cholesterol (g7‐NPs‐Chol), which per se is not blood–brain barrier (BBB) permeable, to obtain high‐rate cholesterol delivery into the brain after intraperitoneal injection in HD mice. We report that g7‐NPs, in contrast to unmodified NPs, efficiently crossed the BBB and localized in glial and neuronal cells in different brain regions. We also found that repeated systemic delivery of g7‐NPs‐Chol rescued synaptic and cognitive dysfunction and partially improved global activity in HD mice. These results demonstrate that cholesterol supplementation to the HD brain reverses functional alterations associated with HD and highlight the potential of this new drug‐administration route to the diseased brain.
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Affiliation(s)
- Marta Valenza
- Department of BioSciences, Centre for Stem Cell Research Università degli Studi di Milano, Milan, Italy
| | - Jane Y Chen
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience Brain Research Institute David Geffen School of Medicine University of California Los Angeles, Los Angeles, CA, USA
| | - Eleonora Di Paolo
- Department of BioSciences, Centre for Stem Cell Research Università degli Studi di Milano, Milan, Italy
| | - Barbara Ruozi
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Daniela Belletti
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Costanza Ferrari Bardile
- Department of BioSciences, Centre for Stem Cell Research Università degli Studi di Milano, Milan, Italy
| | - Valerio Leoni
- Neurological Institute C. Besta, Milan, Italy Laboratory of Clinical Chemistry, Ospedale di Circolo e Fondazione Macchi, Varese, Italy
| | | | - Elisa Brilli
- Department of BioSciences, Centre for Stem Cell Research Università degli Studi di Milano, Milan, Italy
| | | | - Marina M Boido
- Neuroscience Institute Cavalieri Ottolenghi Neuroscience Institute of Turin, Orbassano Turin, Italy
| | - Alessandro Vercelli
- Neuroscience Institute Cavalieri Ottolenghi Neuroscience Institute of Turin, Orbassano Turin, Italy
| | - Maria A Vandelli
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Flavio Forni
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Carlos Cepeda
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience Brain Research Institute David Geffen School of Medicine University of California Los Angeles, Los Angeles, CA, USA
| | - Michael S Levine
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience Brain Research Institute David Geffen School of Medicine University of California Los Angeles, Los Angeles, CA, USA
| | - Giovanni Tosi
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Elena Cattaneo
- Department of BioSciences, Centre for Stem Cell Research Università degli Studi di Milano, Milan, Italy
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27
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Kasimov MR, Zakyrjanova GF, Giniatullin AR, Zefirov AL, Petrov AM. Similar oxysterols may lead to opposite effects on synaptic transmission: Olesoxime versus 5α-cholestan-3-one at the frog neuromuscular junction. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:606-16. [PMID: 27102612 DOI: 10.1016/j.bbalip.2016.04.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 03/17/2016] [Accepted: 04/15/2016] [Indexed: 02/03/2023]
Abstract
Cholesterol oxidation products frequently have a high biological activity. In the present study, we have used microelectrode recording of end plate currents and FM-based optical detection of synaptic vesicle exo-endocytosis to investigate the effects of two structurally similar oxysterols, olesoxime (cholest-4-en-3-one, oxime) and 5ɑ-cholestan-3-one (5ɑCh3), on neurotransmission at the frog neuromuscular junction. Olesoxime is an exogenous, potentially neuroprotective, substance and 5ɑCh3 is an intermediate product in cholesterol metabolism, which is elevated in the case of cerebrotendinous xanthomatosis. We found that olesoxime slightly increased evoked neurotransmitter release in response to a single stimulus and significantly reduced synaptic depression during high frequency activity. The last effect was due to an increase in both the number of synaptic vesicles involved in exo-endocytosis and the rate of synaptic vesicle recycling. In contrast, 5ɑCh3 reduced evoked neurotransmitter release during the low- and high frequency synaptic activities. The depressant action of 5ɑCh3 was associated with a reduction in the number of synaptic vesicles participating in exo- and endocytosis during high frequency stimulation, without a change in rate of the synaptic vesicle recycling. Of note, olesoxime increased the staining of synaptic membranes with the B-subunit of cholera toxin and the formation of fluorescent ganglioside GM1 clusters, and decreased the fluorescence of 22-NBD-cholesterol, while 5ɑCh3 had the opposite effects, suggesting that the two oxysterols have different effects on lipid raft stability. Taken together, these data show that these two structurally similar oxysterols induce marked different changes in neuromuscular transmission which are related with the alteration in synaptic vesicle cycle.
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Affiliation(s)
- M R Kasimov
- Department of Normal Physiology, Kazan State Medical University, Kazan 420012, Russia
| | - G F Zakyrjanova
- Department of Normal Physiology, Kazan State Medical University, Kazan 420012, Russia
| | - A R Giniatullin
- Department of Normal Physiology, Kazan State Medical University, Kazan 420012, Russia
| | - A L Zefirov
- Department of Normal Physiology, Kazan State Medical University, Kazan 420012, Russia
| | - A M Petrov
- Department of Normal Physiology, Kazan State Medical University, Kazan 420012, Russia.
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28
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Diffusional spread and confinement of newly exocytosed synaptic vesicle proteins. Nat Commun 2015; 6:8392. [PMID: 26399746 PMCID: PMC4598626 DOI: 10.1038/ncomms9392] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 08/18/2015] [Indexed: 01/01/2023] Open
Abstract
Neurotransmission relies on the calcium-triggered exocytic fusion of non-peptide neurotransmitter-containing small synaptic vesicles (SVs) with the presynaptic membrane at active zones (AZs) followed by compensatory endocytic retrieval of SV membranes. Here, we study the diffusional fate of newly exocytosed SV proteins in hippocampal neurons by high-resolution time-lapse imaging. Newly exocytosed SV proteins rapidly disperse within the first seconds post fusion until confined within the presynaptic bouton. Rapid diffusional spread and confinement is followed by slow reclustering of SV proteins at the periactive endocytic zone. Confinement within the presynaptic bouton is mediated in part by SV protein association with the clathrin-based endocytic machinery to limit diffusional spread of newly exocytosed SV proteins. These data suggest that diffusion, and axonal escape of newly exocytosed vesicle proteins, are counteracted by the clathrin-based endocytic machinery together with a presynaptic diffusion barrier. Neurotransmission is mediated by synaptic vesicles (SVs) fusion with the plasma membrane near active zones. Here, Gimber et al. observe that rapid diffusional spread and confinement is followed by slow reclustering of SV proteins at the periactive endocytic zone through SV protein association with the clathrin-based machinery.
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29
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Frech MJ, Rabenstein M, Bovensiepen K, Rost S, Rolfs A. Cyclodextrin Alters GABAergic Input to CA1 Pyramidal Cells in Wild-Type But Not in NPC1-Deficient Mice. Biores Open Access 2015; 4:358-62. [PMID: 26392920 PMCID: PMC4556338 DOI: 10.1089/biores.2015.0023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Niemann–Pick type C1 disease (NPC1) is a neurodegenerative disorder caused by mutations in the NPC1 gene. Actual, no causative treatment for NPC1 is available, although some drugs have been proven to be beneficial to patients, for example, 2-hydroxypropyl-β-cyclodextrin (CDX). In this study, we used the BALB/c_Nctr-Npc1m1N/-J mouse strain to study the effect of CDX, which is described to prolong the life span and to alleviate the pathogenic phenotype. By means of patch clamp recordings, we measured inhibitory postsynaptic currents (IPSCs) of CA1 pyramidal cells of CDX-treated and -untreated animals to elucidate the influence of CDX on the synaptic transmission. Surprisingly, CDX induced a significantly higher GABAergic IPSC frequency in wild-type mice than in NPC1−/− mice. Although the IPSCs were mainly GABAergic, we observed a significant reduction of the IPSC frequency in the presence of the glycine receptor antagonist strychnine. The effect of strychnine did not differ in untreated and treated animals, indicating that the effect of CDX was most likely not based on an interaction with glycinergic transmission machinery. However, the unexpected effect of CDX on the GABAergic synaptic transmission is of special interest as a disturbance plays, for example, a crucial role in epilepsy and, moreover, as CDX is currently under investigation as a treatment for NPC1 in humans.
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Affiliation(s)
- Moritz J Frech
- Albrecht-Kossel-Institute for Neuroregeneration, University of Rostock , Rostock, Germany
| | - Michael Rabenstein
- Albrecht-Kossel-Institute for Neuroregeneration, University of Rostock , Rostock, Germany
| | - Katja Bovensiepen
- Albrecht-Kossel-Institute for Neuroregeneration, University of Rostock , Rostock, Germany
| | - Sebastian Rost
- Albrecht-Kossel-Institute for Neuroregeneration, University of Rostock , Rostock, Germany
| | - Arndt Rolfs
- Albrecht-Kossel-Institute for Neuroregeneration, University of Rostock , Rostock, Germany
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30
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Yue HY, Xu J. Cholesterol regulates multiple forms of vesicle endocytosis at a mammalian central synapse. J Neurochem 2015; 134:247-60. [PMID: 25893258 DOI: 10.1111/jnc.13129] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 03/01/2015] [Accepted: 03/31/2015] [Indexed: 01/10/2023]
Abstract
Endocytosis in synapses sustains neurotransmission by recycling vesicle membrane and maintaining the homeostasis of synaptic membrane. A role of membrane cholesterol in synaptic endocytosis remains controversial because of conflicting observations, technical limitations in previous studies, and potential interference from non-specific effects after cholesterol manipulation. Furthermore, it remains unclear whether cholesterol participates in distinct forms of endocytosis that function under different activity levels. In this study, applying the whole-cell membrane capacitance measurement to monitor endocytosis in real time at the rat calyx of Held terminals, we found that disrupting cholesterol with dialysis of cholesterol oxidase or methyl-β-cyclodextrin impaired three different forms of endocytosis, including slow endocytosis, rapid endocytosis, and endocytosis of the retrievable membrane that exists at the surface before stimulation. The effects were observed when disruption of cholesterol was mild enough not to change Ca(2+) channel current or vesicle exocytosis, indicative of stringent cholesterol requirement in synaptic endocytosis. Extracting cholesterol with high concentrations of methyl-β-cyclodextrin reduced exocytosis, mainly by decreasing the readily releasable pool and the vesicle replenishment after readily releasable pool depletion. Our study suggests that cholesterol is an important, universal regulator in multiple forms of vesicle endocytosis at mammalian central synapses.
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Affiliation(s)
- Hai-Yuan Yue
- Department of Neuroscience and Regenerative Medicine, Georgia Regents University, Augusta, Georgia, USA
| | - Jianhua Xu
- Department of Neuroscience and Regenerative Medicine, Georgia Regents University, Augusta, Georgia, USA.,Department of Neurology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, USA
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31
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Li S, Xu S, Roelofs BA, Boyman L, Lederer WJ, Sesaki H, Karbowski M. Transient assembly of F-actin on the outer mitochondrial membrane contributes to mitochondrial fission. ACTA ACUST UNITED AC 2014; 208:109-23. [PMID: 25547155 PMCID: PMC4284235 DOI: 10.1083/jcb.201404050] [Citation(s) in RCA: 151] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dynamic assembly and disassembly of F-actin on mitochondria participate in Drp1-mediated mitochondrial fission. In addition to established membrane remodeling roles in various cellular locations, actin has recently emerged as a participant in mitochondrial fission. However, the underlying mechanisms of its participation remain largely unknown. We report that transient de novo F-actin assembly on the mitochondria occurs upon induction of mitochondrial fission and F-actin accumulates on the mitochondria without forming detectable submitochondrial foci. Impairing mitochondrial division through Drp1 knockout or inhibition prolonged the time of mitochondrial accumulation of F-actin and also led to abnormal mitochondrial accumulation of the actin regulatory factors cortactin, cofilin, and Arp2/3 complexes, suggesting that disassembly of mitochondrial F-actin depends on Drp1 activity. Furthermore, down-regulation of actin regulatory proteins led to elongation of mitochondria, associated with mitochondrial accumulation of Drp1. In addition, depletion of cortactin inhibited Mfn2 down-regulation– or FCCP-induced mitochondrial fragmentation. These data indicate that the dynamic assembly and disassembly of F-actin on the mitochondria participates in Drp1-mediated mitochondrial fission.
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Affiliation(s)
- Sunan Li
- Center for Biomedical Engineering and Technology, Department of Biochemistry and Molecular Biology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201 Center for Biomedical Engineering and Technology, Department of Biochemistry and Molecular Biology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Shan Xu
- Center for Biomedical Engineering and Technology, Department of Biochemistry and Molecular Biology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201 Center for Biomedical Engineering and Technology, Department of Biochemistry and Molecular Biology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Brian A Roelofs
- Center for Biomedical Engineering and Technology, Department of Biochemistry and Molecular Biology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201 Center for Biomedical Engineering and Technology, Department of Biochemistry and Molecular Biology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Liron Boyman
- Center for Biomedical Engineering and Technology, Department of Biochemistry and Molecular Biology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201 Center for Biomedical Engineering and Technology, Department of Biochemistry and Molecular Biology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201
| | - W Jonathan Lederer
- Center for Biomedical Engineering and Technology, Department of Biochemistry and Molecular Biology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201 Center for Biomedical Engineering and Technology, Department of Biochemistry and Molecular Biology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Hiromi Sesaki
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Mariusz Karbowski
- Center for Biomedical Engineering and Technology, Department of Biochemistry and Molecular Biology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201 Center for Biomedical Engineering and Technology, Department of Biochemistry and Molecular Biology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201
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32
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Petrov AM, Yakovleva AA, Zefirov AL. Role of membrane cholesterol in spontaneous exocytosis at frog neuromuscular synapses: reactive oxygen species-calcium interplay. J Physiol 2014; 592:4995-5009. [PMID: 25326454 DOI: 10.1113/jphysiol.2014.279695] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Using electrophysiological and optical techniques, we studied the mechanisms by which cholesterol depletion stimulates spontaneous transmitter release by exocytosis at the frog neuromuscular junction. We found that methyl-β-cyclodextrin (MCD, 10 mM)-mediated exhaustion of cholesterol resulted in the enhancement of reactive oxygen species (ROS) production, which was prevented by the antioxidant N-acetyl cysteine (NAC) and the NADPH oxidase inhibitor apocynin. An increase in ROS levels occurred both extra- and intracellularly, and it was associated with lipid peroxidation in synaptic regions. Cholesterol depletion provoked a rise in the intracellular Ca(2+) concentration, which was diminished by NAC and transient receptor potential vanilloid (TRPV) channel blockers (ruthenium red and capsazepine). By contrast, the MCD-induced rise in [Ca(2+)]i remained unaffected if Ca(2+) release from endoplasmic stores was blocked by TMB8 (8-(diethylamino)octyl-3,4,5-trimethoxybenzoate hydrochloride). The effects of cholesterol depletion on spontaneous release and exocytosis were significantly reduced by the antioxidant, intracellular Ca(2+) chelation with BAPTA-AM and blockers of TRPV channels. Bath application of the calcineurin antagonist cyclosporine A blocked MCD-induced enhancement of spontaneous release/exocytosis, whereas okadaic acid, an inhibitor of phosphatases PP1 and PP2A, had no effect. Thus, our findings indicate that enhancement of spontaneous exocytosis induced by cholesterol depletion may depend on ROS generation, leading to an influx of Ca(2+) via TRPV channels and, subsequently, activation of calcineurin.
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Affiliation(s)
- Alexey M Petrov
- Department of Normal Physiology, Kazan State Medical University, Kazan, 420012, Russia
| | | | - Andrey L Zefirov
- Department of Normal Physiology, Kazan State Medical University, Kazan, 420012, Russia
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33
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Martín MG, Pfrieger F, Dotti CG. Cholesterol in brain disease: sometimes determinant and frequently implicated. EMBO Rep 2014; 15:1036-52. [PMID: 25223281 DOI: 10.15252/embr.201439225] [Citation(s) in RCA: 207] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cholesterol is essential for neuronal physiology, both during development and in the adult life: as a major component of cell membranes and precursor of steroid hormones, it contributes to the regulation of ion permeability, cell shape, cell-cell interaction, and transmembrane signaling. Consistently, hereditary diseases with mutations in cholesterol-related genes result in impaired brain function during early life. In addition, defects in brain cholesterol metabolism may contribute to neurological syndromes, such as Alzheimer's disease (AD), Huntington's disease (HD), and Parkinson's disease (PD), and even to the cognitive deficits typical of the old age. In these cases, brain cholesterol defects may be secondary to disease-causing elements and contribute to the functional deficits by altering synaptic functions. In the first part of this review, we will describe hereditary and non-hereditary causes of cholesterol dyshomeostasis and the relationship to brain diseases. In the second part, we will focus on the mechanisms by which perturbation of cholesterol metabolism can affect synaptic function.
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Affiliation(s)
- Mauricio G Martín
- Instituto de Investigaciones Médicas Mercedes y Martín Ferreyra (INIMEC-CONICET-UNC), Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Frank Pfrieger
- Institute of Cellular and Integrative Neurosciences, CNRS UPR 3212, University of Strasbourg, Strasbourg, France
| | - Carlos G Dotti
- Centro Biología Molecular 'Severo Ochoa' CSIC-UAM, Madrid, Spain
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34
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Vance JE, Karten B. Niemann-Pick C disease and mobilization of lysosomal cholesterol by cyclodextrin. J Lipid Res 2014; 55:1609-21. [PMID: 24664998 DOI: 10.1194/jlr.r047837] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Indexed: 12/31/2022] Open
Abstract
Niemann-Pick type C (NPC) disease is a lysosomal storage disease in which endocytosed cholesterol becomes sequestered in late endosomes/lysosomes (LEs/Ls) because of mutations in either the NPC1 or NPC2 gene. Mutations in either of these genes can lead to impaired functions of the NPC1 or NPC2 proteins and progressive neurodegeneration as well as liver and lung disease. NPC1 is a polytopic protein of the LE/L limiting membrane, whereas NPC2 is a soluble protein in the LE/L lumen. These two proteins act in tandem and promote the export of cholesterol from LEs/Ls. Consequently, a defect in either NPC1 or NPC2 causes cholesterol accumulation in LEs/Ls. In this review, we summarize the molecular mechanisms leading to NPC disease, particularly in the CNS. Recent exciting data on the mechanism by which the cholesterol-sequestering agent cyclodextrin can bypass the functions of NPC1 and NPC2 in the LEs/Ls, and mobilize cholesterol from LEs/Ls, will be highlighted. Moreover, the possible use of cyclodextrin as a valuable therapeutic agent for treatment of NPC patients will be considered.
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Affiliation(s)
- Jean E Vance
- The Group on Molecular and Cell Biology of Lipids and Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Barbara Karten
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada
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35
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Dason JS, Charlton MP. A novel extraction protocol to probe the role of cholesterol in synaptic vesicle recycling. Methods Mol Biol 2014; 1174:361-373. [PMID: 24947395 DOI: 10.1007/978-1-4939-0944-5_25] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Cholesterol helps to stabilize membrane fluidity and many membrane proteins interact with cholesterol and are functionally clustered in cholesterol rich "rafts." Synaptic vesicle (SV) membranes are enriched in cholesterol in comparison to other organelles. Attempts to study the function of this high cholesterol content have been hampered by the inability to extract cholesterol from SVs in live presynaptic terminals. Here, we describe a method to extract vesicular cholesterol using a temperature-sensitive Drosophila dynamin mutant, shibire-ts1 (shi), to trap SVs on the plasma membrane. Trapped SVs are more accessible to cholesterol extraction by the cholesterol chelator, methyl-β-cyclodextrin (MβCD). This method can likely be extended to extract other lipids from SVs and could also be used to add lipids. We speculate that this method could be used on mammalian preparations in conjunction with dynamin inhibitors.
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Affiliation(s)
- Jeffrey S Dason
- Department of Physiology, University of Toronto, Medical Sciences Building, 1 King's College Circle, Toronto, ON, Canada, M5S1A8,
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