1
|
Bucher ML, Dunn AR, Bradner JM, Egerton KS, Burkett JP, Johnson MA, Miller GW. Synaptic vesicle glycoprotein 2C enhances vesicular storage of dopamine and counters dopaminergic toxicity. Eur J Neurosci 2024; 59:2483-2501. [PMID: 38532289 DOI: 10.1111/ejn.16311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 02/14/2024] [Accepted: 02/22/2024] [Indexed: 03/28/2024]
Abstract
Dopaminergic neurons of the substantia nigra exist in a persistent state of vulnerability resulting from high baseline oxidative stress, high-energy demand, and broad unmyelinated axonal arborisations. Impairments in the storage of dopamine compound this stress because of cytosolic reactions that transform the vital neurotransmitter into an endogenous neurotoxicant, and this toxicity is thought to contribute to the dopamine neuron degeneration that occurs Parkinson's disease. We have previously identified synaptic vesicle glycoprotein 2C (SV2C) as a modifier of vesicular dopamine function, demonstrating that genetic ablation of SV2C in mice results in decreased dopamine content and evoked dopamine release in the striatum. Here, we adapted a previously published in vitro assay utilising false fluorescent neurotransmitter 206 (FFN206) to visualise how SV2C regulates vesicular dopamine dynamics and determined that SV2C promotes the uptake and retention of FFN206 within vesicles. In addition, we present data indicating that SV2C enhances the retention of dopamine in the vesicular compartment with radiolabelled dopamine in vesicles isolated from immortalised cells and from mouse brain. Further, we demonstrate that SV2C enhances the ability of vesicles to store the neurotoxicant 1-methyl-4-phenylpyridinium (MPP+) and that genetic ablation of SV2C results in enhanced 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced vulnerability in mice. Together, these findings suggest that SV2C functions to enhance vesicular storage of dopamine and neurotoxicants and helps maintain the integrity of dopaminergic neurons.
Collapse
Affiliation(s)
- Meghan L Bucher
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York, USA
| | - Amy R Dunn
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- The Jackson Laboratory, Bar Harbor, Maine, USA
| | - Joshua M Bradner
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York, USA
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- AbbVie CRC, Cambridge, Massachusetts, USA
| | - Kristen Stout Egerton
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- School of Education and Health Sciences, North Central College, Naperville, Illinois, USA
| | - James P Burkett
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- Department of Neurosciences, University of Toledo College of Medicine, Toledo, Ohio, USA
| | - Michelle A Johnson
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- College of Arts and Sciences, Oberlin College, Oberlin, Ohio, USA
| | - Gary W Miller
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York, USA
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- Department of Molecular Pharmacology and Therapeutics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
| |
Collapse
|
2
|
Bucher ML, Dunn AR, Bradner JM, Egerton KS, Burkett JP, Johnson MA, Miller GW. Synaptic vesicle glycoprotein 2C enhances vesicular storage of dopamine and counters dopaminergic toxicity. bioRxiv 2023:2023.06.26.546143. [PMID: 37425736 PMCID: PMC10326994 DOI: 10.1101/2023.06.26.546143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Dopaminergic neurons of the substantia nigra exist in a persistent state of vulnerability resulting from high baseline oxidative stress, high energy demand, and broad unmyelinated axonal arborizations. Impairments in the storage of dopamine compound this stress due to cytosolic reactions that transform the vital neurotransmitter into an endogenous neurotoxicant, and this toxicity is thought to contribute to the dopamine neuron degeneration that occurs Parkinson's disease. We have previously identified synaptic vesicle glycoprotein 2C (SV2C) as a modifier of vesicular dopamine function, demonstrating that genetic ablation of SV2C in mice results in decreased dopamine content and evoked dopamine release in the striatum. Here, we adapted a previously published in vitro assay utilizing false fluorescent neurotransmitter 206 (FFN206) to visualize how SV2C regulates vesicular dopamine dynamics and determined that SV2C promotes the uptake and retention of FFN206 within vesicles. In addition, we present data indicating that SV2C enhances the retention of dopamine in the vesicular compartment with radiolabeled dopamine in vesicles isolated from immortalized cells and from mouse brain. Further, we demonstrate that SV2C enhances the ability of vesicles to store the neurotoxicant 1-methyl-4-phenylpyridinium (MPP+) and that genetic ablation of SV2C results in enhanced 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced vulnerability in mice. Together, these findings suggest that SV2C functions to enhance vesicular storage of dopamine and neurotoxicants, and helps maintain the integrity of dopaminergic neurons.
Collapse
Affiliation(s)
- Meghan L Bucher
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
| | - Amy R Dunn
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Joshua M Bradner
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Kristen Stout Egerton
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - James P Burkett
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Michelle A Johnson
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Gary W Miller
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
- Department of Molecular Pharmacology and Therapeutics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10031, USA
| |
Collapse
|
3
|
Kalia V, Niedzwiecki MM, Bradner JM, Lau FK, Anderson FL, Bucher ML, Manz KE, Schlotter AP, Fuentes ZC, Pennell KD, Picard M, Walker DI, Hu WT, Jones DP, Miller GW. Cross-species metabolomic analysis of tau- and DDT-related toxicity. PNAS Nexus 2022; 1:pgac050. [PMID: 35707205 PMCID: PMC9186048 DOI: 10.1093/pnasnexus/pgac050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 04/28/2022] [Indexed: 01/29/2023]
Abstract
Exposure to the pesticide dichlorodiphenyltrichloroethane (DDT) has been associated with increased risk of Alzheimer's disease (AD), a disease also associated with hyperphosphorylated tau (p-tau) protein aggregation. We investigated whether exposure to DDT can exacerbate tau protein toxicity in Caenorhabditiselegans using a transgenic strain that expresses human tau protein prone to aggregation by measuring changes in size, swim behavior, respiration, lifespan, learning, and metabolism. In addition, we examined the association between cerebrospinal fluid (CSF) p-tau protein-as a marker of postmortem tau burden-and global metabolism in both a human population study and in C. elegans, using the same p-tau transgenic strain. From the human population study, plasma and CSF-derived metabolic features associated with p-tau levels were related to drug, amino acid, fatty acid, and mitochondrial metabolism pathways. A total of five metabolites overlapped between plasma and C. elegans, and four between CSF and C. elegans. DDT exacerbated the inhibitory effect of p-tau protein on growth and basal respiration. In the presence of p-tau protein, DDT induced more curling and was associated with reduced levels of amino acids but increased levels of uric acid and adenosylselenohomocysteine. Our findings in C. elegans indicate that DDT exposure and p-tau aggregation both inhibit mitochondrial function and DDT exposure can exacerbate the mitochondrial inhibitory effects of p-tau aggregation. Further, biological pathways associated with exposure to DDT and p-tau protein appear to be conserved between species.
Collapse
Affiliation(s)
- Vrinda Kalia
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, 10032 USA
| | - Megan M Niedzwiecki
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY, 10029 USA
| | - Joshua M Bradner
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, 10032 USA
| | - Fion K Lau
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, 10032 USA
| | - Faith L Anderson
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, 10032 USA
| | - Meghan L Bucher
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, 10032 USA
| | - Katherine E Manz
- School of Engineering, Brown University, Providence, RI, 02912 USA
| | - Alexa Puri Schlotter
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, 10032 USA
| | - Zoe Coates Fuentes
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY, 10029 USA
| | - Kurt D Pennell
- School of Engineering, Brown University, Providence, RI, 02912 USA
| | - Martin Picard
- Department of Neurology, Department of Psychiatry, Columbia University Irving Medical Center, New York, NY, 10032 USA
| | - Douglas I Walker
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY, 10029 USA
| | - William T Hu
- Department of Neurology, Rutgers Biomedical and Health Sciences, New Brunswick, NJ, 08901 USA
| | - Dean P Jones
- Division of Pulmonary, Allergy and Critical Medicine, Department of Medicine, School of Medicine, Emory University, Atlanta, GA, 30322 USA
| | - Gary W Miller
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, 10032 USA
| |
Collapse
|
4
|
Bradner JM, Kalia V, Lau FK, Sharma M, Bucher ML, Johnson M, Chen M, Walker DI, Jones DP, Miller GW. Genetic or Toxicant-Induced Disruption of Vesicular Monoamine Storage and Global Metabolic Profiling in Caenorhabditis elegans. Toxicol Sci 2021; 180:313-324. [PMID: 33538833 PMCID: PMC8041460 DOI: 10.1093/toxsci/kfab011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The proper storage and release of monoamines contributes to a wide range of neuronal activity. Here, we examine the effects of altered vesicular monoamine transport in the nematode Caenorhabditis elegans. The gene cat-1 is responsible for the encoding of the vesicular monoamine transporter (VMAT) in C. elegans and is analogous to the mammalian vesicular monoamine transporter 2 (VMAT2). Our laboratory has previously shown that reduced VMAT2 activity confers vulnerability on catecholamine neurons in mice. The purpose of this article was to determine whether this function is conserved and to determine the impact of reduced VMAT activity in C. elegans. Here we show that deletion of cat-1/VMAT increases sensitivity to the neurotoxicant 1-methyl-4-phenylpyridinium (MPP+) as measured by enhanced degeneration of dopamine neurons. Reduced cat-1/VMAT also induces changes in dopamine-mediated behaviors. High-resolution mass spectrometry-based metabolomics in the whole organism reveals changes in amino acid metabolism, including tyrosine metabolism in the cat-1/VMAT mutants. Treatment with MPP+ disrupted tryptophan metabolism. Both conditions altered glycerophospholipid metabolism, suggesting a convergent pathway of neuronal dysfunction. Our results demonstrate the evolutionarily conserved nature of monoamine function in C. elegans and further suggest that high-resolution mass spectrometry-based metabolomics can be used in this model to study environmental and genetic contributors to complex human disease.
Collapse
Affiliation(s)
- Joshua M Bradner
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York 10032, USA
| | - Vrinda Kalia
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York 10032, USA
| | - Fion K Lau
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York 10032, USA
| | - Monica Sharma
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York 10032, USA
| | - Meghan L Bucher
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York 10032, USA
| | - Michelle Johnson
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia 30322, USA
| | - Merry Chen
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia 30322, USA
| | - Douglas I Walker
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Dean P Jones
- Department of Medicine, School of Medicine, Emory University, Atlanta, Georgia 30303, USA
| | - Gary W Miller
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York 10032, USA
| |
Collapse
|
5
|
Black CA, Bucher ML, Bradner JM, Jonas L, Igarza K, Miller GW. Assessing Vesicular Monoamine Transport and Toxicity Using Fluorescent False Neurotransmitters. Chem Res Toxicol 2020; 34:1256-1264. [PMID: 33378168 DOI: 10.1021/acs.chemrestox.0c00380] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Impairments in the vesicular packaging of dopamine result in an accumulation of dopamine in the cytosol. Cytosolic dopamine is vulnerable to two metabolic processes-enzymatic catabolism and enzymatic- or auto-oxidation-that form toxic metabolites and generate reactive oxygen species. Alterations in the expression or activity of the vesicular monoamine transporter 2 (VMAT2), which transports monoamines such as dopamine from the cytosol into the synaptic vesicle, result in dysregulated dopamine packaging. Here, we developed a series of assays using the fluorescent false neurotransmitter 206 (FFN206) to visualize VMAT2-mediated vesicular packaging at baseline and following pharmacological and toxicological manipulations. As a proof of principle, we observed a significant reduction in vesicular FFN206 packaging after treatment with the VMAT2 inhibitors reserpine (IC50: 73.1 nM), tetrabenazine (IC50: 30.4 nM), methamphetamine (IC50: 2.4 μM), and methylphenidate (IC50: 94.3 μM). We then applied the assay to investigate the consequences on vesicular packaging by environmental toxicants including the pesticides paraquat, rotenone, and chlorpyrifos, as well as the halogenated compounds unichlor, perfluorooctanesulfonic acid, Paroil, Aroclor 1260, and hexabromocyclododecane. Several of the environmental toxicants showed minor impairment of the vesicular FFN206 loading, suggesting that the toxicants are weak VMAT2 inhibitors at the concentrations tested. The assay presented here can be applied to investigate the effect of additional pharmacological compounds and environmental toxicants on vesicular function, which will provide insight into how exposures to such factors are involved in the pathogenesis of monoaminergic diseases such as Parkinson's disease, and the assay can be used to identify pharmacological agents that influence VMAT2 activity.
Collapse
Affiliation(s)
- Carlie A Black
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia 30322, United States
| | - Meghan L Bucher
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York 10032, United States
| | - Joshua M Bradner
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York 10032, United States
| | - Lauren Jonas
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia 30322, United States
| | - Kenny Igarza
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia 30322, United States
| | - Gary W Miller
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York 10032, United States
| |
Collapse
|
6
|
Rampoldi A, Singh M, Wu Q, Duan M, Jha R, Maxwell JT, Bradner JM, Zhang X, Saraf A, Miller GW, Gibson G, Brown LA, Xu C. Cardiac Toxicity From Ethanol Exposure in Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes. Toxicol Sci 2020; 169:280-292. [PMID: 31059573 DOI: 10.1093/toxsci/kfz038] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Alcohol use prior to and during pregnancy remains a significant societal problem and can lead to developmental fetal abnormalities including compromised myocardia function and increased risk for heart disease later in life. Alcohol-induced cardiac toxicity has traditionally been studied in animal-based models. These models have limitations due to physiological differences from human cardiomyocytes (CMs) and are also not suitable for high-throughput screening. We hypothesized that human-induced pluripotent stem cell-derived CMs (hiPSC-CMs) could serve as a useful tool to study alcohol-induced cardiac defects and/or toxicity. In this study, hiPSC-CMs were treated with ethanol at doses corresponding to the clinically relevant levels of alcohol intoxication. hiPSC-CMs exposed to ethanol showed a dose-dependent increase in cellular damage and decrease in cell viability, corresponding to increased production of reactive oxygen species. Furthermore, ethanol exposure also generated dose-dependent increased irregular Ca2+ transients and contractility in hiPSC-CMs. RNA-seq analysis showed significant alteration in genes belonging to the potassium voltage-gated channel family or solute carrier family, partially explaining the irregular Ca2+ transients and contractility in ethanol-treated hiPSC-CMs. RNA-seq also showed significant upregulation in the expression of genes associated with collagen and extracellular matrix modeling, and downregulation of genes involved in cardiovascular system development and actin filament-based process. These results suggest that hiPSC-CMs can be a novel and physiologically relevant system for the study of alcohol-induced cardiac toxicity.
Collapse
Affiliation(s)
- Antonio Rampoldi
- Division of Pediatric Cardiology, Department of Pediatrics, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, Georgia
| | - Monalisa Singh
- Division of Pediatric Cardiology, Department of Pediatrics, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, Georgia
| | - Qingling Wu
- Division of Pediatric Cardiology, Department of Pediatrics, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, Georgia.,Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Meixue Duan
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Rajneesh Jha
- Division of Pediatric Cardiology, Department of Pediatrics, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, Georgia
| | - Joshua T Maxwell
- Division of Pediatric Cardiology, Department of Pediatrics, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, Georgia
| | - Joshua M Bradner
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia
| | | | - Anita Saraf
- Division of Pediatric Cardiology, Department of Pediatrics, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, Georgia.,Division of Cardiology, Emory University School of Medicine, Atlanta, Georgia
| | - Gary W Miller
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia
| | - Greg Gibson
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Lou Ann Brown
- Division of Pediatric Cardiology, Department of Pediatrics, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, Georgia
| | - Chunhui Xu
- Division of Pediatric Cardiology, Department of Pediatrics, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, Georgia.,Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| |
Collapse
|
7
|
Kline EM, Butkovich LM, Bradner JM, Chang J, Gelbard H, Goodfellow V, Caudle WM, Tansey MG. The second generation mixed lineage kinase-3 (MLK3) inhibitor CLFB-1134 protects against neurotoxin-induced nigral dopaminergic neuron loss. Exp Neurol 2019; 318:157-164. [PMID: 31077715 PMCID: PMC6592621 DOI: 10.1016/j.expneurol.2019.05.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 05/01/2019] [Accepted: 05/07/2019] [Indexed: 11/29/2022]
Abstract
Dopaminergic neurons express mixed lineage kinases which regulate the expression of cell death genes. In Parkinson's disease, cell death via apoptosis is prevalent, and previous work testing mixed lineage kinase inhibitors in animal models suggested the inhibitors had some neuroprotective potential. CLFB-1134 is a new, brain-penetrant inhibitor specific for MLK3, tested here in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of dopaminergic depletion and nigral neuron death in mice. After ensuring that treatment with CLFB-1134 did not alter conversion of MPTP to MPP+, we demonstrated CLFB-1134's inhibition of MLK3 and neuroprotective efficacy. Specifically we evaluated the integrity of the nigrostriatal dopamine system following MPTP by assessing protein expression, high performance liquid chromatography, and immunohistology with stereology. We found that CLFB-1134 achieves protection of striatal dopaminergic terminals and nigral cell bodies when dosed simultaneously or following MPTP treatment. By preventing phosphorylation of JNK and other downstream targets of MLK3, CLFB-1134 protects against the neurotoxin MPTP. Inhibition of MLK3 may be a valid target for future work investigating treatment of Parkinson's disease.
Collapse
Affiliation(s)
- Elizabeth M Kline
- Emory University, 615 Michael St, Atlanta, GA 30322, United States of America.
| | - Laura M Butkovich
- Emory University, 615 Michael St, Atlanta, GA 30322, United States of America.
| | - Joshua M Bradner
- Emory University, 1518 Clifton Rd NE, Atlanta, GA 30322, United States of America.
| | - Jianjun Chang
- Emory University, 615 Michael St, Atlanta, GA 30322, United States of America.
| | - Harris Gelbard
- University of Rochester Medical Center, Box 645, 601 Elmwood Avenue, Rochester, NY 14642, United States of America.
| | - Val Goodfellow
- Califia Bio Inc., San Diego, CA, United States of America.
| | - W Michael Caudle
- Emory University, 1518 Clifton Rd NE, Atlanta, GA 30322, United States of America.
| | - Malú G Tansey
- Emory University, 615 Michael St, Atlanta, GA 30322, United States of America.
| |
Collapse
|
8
|
Bhattacharya S, Ma Y, Dunn AR, Bradner JM, Scimemi A, Miller GW, Traynelis SF, Wichmann T. NMDA receptor blockade ameliorates abnormalities of spike firing of subthalamic nucleus neurons in a parkinsonian nonhuman primate. J Neurosci Res 2018; 96:1324-1335. [PMID: 29577359 PMCID: PMC5980712 DOI: 10.1002/jnr.24230] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 01/25/2018] [Accepted: 02/08/2018] [Indexed: 12/21/2022]
Abstract
N-methyl-D-aspartate receptors (NMDARs) are ion channels comprising tetrameric assemblies of GluN1 and GluN2 receptor subunits that mediate excitatory neurotransmission in the central nervous system. Of the four different GluN2 subunits, the GluN2D subunit-containing NMDARs have been suggested as a target for antiparkinsonian therapy because of their expression pattern in some of the basal ganglia nuclei that show abnormal firing patterns in the parkinsonian state, specifically the subthalamic nucleus (STN). In this study, we demonstrate that blockade of NMDARs altered spike firing in the STN in a male nonhuman primate that had been rendered parkinsonian by treatment with the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. In accompanying experiments in male rodents, we found that GluN2D-NMDAR expression in the STN was reduced in acutely or chronically dopamine-depleted animals. Taken together, our data suggest that blockade of NMDARs in the STN may be a viable antiparkinsonian strategy, but that the ultimate success of this approach may be complicated by parkinsonism-associated changes in NMDAR expression in the STN.
Collapse
Affiliation(s)
| | - Yuxian Ma
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia
| | - Amy R Dunn
- Rollins School of Public Health, Emory University, Atlanta, Georgia
| | - Joshua M Bradner
- Rollins School of Public Health, Emory University, Atlanta, Georgia
| | - Annalisa Scimemi
- Department of Biology, State University of New York at Albany, Albany, New York
| | - Gary W Miller
- Rollins School of Public Health, Emory University, Atlanta, Georgia
| | - Stephen F Traynelis
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia
| | - Thomas Wichmann
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia
- Department of Neurology, Emory University School of Medicine, Atlanta, Georgia
- Morris K. Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia
| |
Collapse
|
9
|
Steves AN, Turry A, Gill B, Clarkson-Townsend D, Bradner JM, Bachli I, Caudle WM, Miller GW, Chan AWS, Easley CA. Per- and polyfluoroalkyl substances impact human spermatogenesis in a stem-cell-derived model. Syst Biol Reprod Med 2018; 64:225-239. [PMID: 29911897 DOI: 10.1080/19396368.2018.1481465] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Per- and polyfluoroalkyl substances (PFASs) represent a highly ubiquitous group of synthetic chemicals used in products ranging from water and oil repellents and lubricants to firefighting foam. These substances can enter and accumulate in multiple tissue matrices in up to 100% of people assessed. Though animal models strongly identify these compounds as male reproductive toxicants, with exposed rodents experiencing declines in sperm count, alterations in hormones, and DNA damage in spermatids, among other adverse outcomes, human studies report conflicting conclusions as to the reproductive toxicity of these chemicals. Using an innovative, human stem-cell-based model of spermatogenesis, we assessed the effects of the PFASs perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and a mixture of PFOS, PFOA, and PFNA for their impacts on human spermatogenesis in vitro under conditions relevant to the general and occupationally exposed populations. Here, we show that PFOS, PFOA, PFNA, and a mixture of PFOS, PFOA, and PFNA do not decrease in vitro germ cell viability, consistent with reports from human studies. These compounds do not affect mitochondrial membrane potential or increase reactive oxygen species generation, and they do not decrease cell viability of spermatogonia, primary spermatocytes, secondary spermatocytes, or spermatids in vitro under the conditions examined. However, exposure to PFOS, PFOA, and PFNA reduces expression of markers for spermatogonia and primary spermatocytes. While not having direct effects on germ cell viability, these effects suggest the potential for long-term impacts on male fertility through the exhaustion of the spermatogonial stem cell pool and abnormalities in primary spermatocytes. ABBREVIATIONS CDC: Centers for Disease Control; DMSO: dimethyl sulfoxide; GHR: growth hormone receptor; hESCs: human embryonic stem cells; PFASs: per- and polyfluoroalkyl substances; PFCs: perfluorinated compounds; PFNA: perfluorononanoic acid; PFOS: perfluorooctanesulfonic acid; PFOA: perfluorooctanoic acid; PLZF: promyelocytic leukemia zinc finger; ROS: reactive oxygen species; HILI: RNA-mediated gene silencing 2; SSC: spermatogonial stem cell.
Collapse
Affiliation(s)
- Alyse N Steves
- a Genetics and Molecular Biology Program , Laney Graduate School, Emory University , Atlanta , GA , USA
| | - Adam Turry
- b College of Public Health , University of Georgia , Athens , GA , USA.,c Regenerative Bioscience Center , University of Georgia , Athens , GA , USA
| | - Brittany Gill
- b College of Public Health , University of Georgia , Athens , GA , USA.,c Regenerative Bioscience Center , University of Georgia , Athens , GA , USA
| | | | - Joshua M Bradner
- d Rollins School of Public Health , Emory University , Atlanta , GA , USA
| | - Ian Bachli
- b College of Public Health , University of Georgia , Athens , GA , USA.,c Regenerative Bioscience Center , University of Georgia , Athens , GA , USA
| | - W Michael Caudle
- d Rollins School of Public Health , Emory University , Atlanta , GA , USA
| | - Gary W Miller
- d Rollins School of Public Health , Emory University , Atlanta , GA , USA
| | - Anthony W S Chan
- e Division of Neuropharmacology and Neurologic Diseases , Yerkes National Primate Research Center , Atlanta , GA , USA.,f Department of Human Genetics , Emory University , Atlanta , GA , USA
| | - Charles A Easley
- b College of Public Health , University of Georgia , Athens , GA , USA.,c Regenerative Bioscience Center , University of Georgia , Athens , GA , USA.,e Division of Neuropharmacology and Neurologic Diseases , Yerkes National Primate Research Center , Atlanta , GA , USA
| |
Collapse
|
10
|
Steves AN, Bradner JM, Fowler KL, Clarkson-Townsend D, Gill BJ, Turry AC, Caudle WM, Miller GW, Chan AWS, Easley CA. Ubiquitous Flame-Retardant Toxicants Impair Spermatogenesis in a Human Stem Cell Model. iScience 2018; 3:161-176. [PMID: 29901031 PMCID: PMC5994764 DOI: 10.1016/j.isci.2018.04.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/27/2018] [Accepted: 04/05/2018] [Indexed: 01/08/2023] Open
Abstract
Sperm counts have rapidly declined in Western males over the past four decades. This rapid decline remains largely unexplained, but exposure to environmental toxicants provides one potential explanation for this decline. Flame retardants are highly prevalent and persistent in the environment, but many have not been assessed for their effects on human spermatogenesis. Using a human stem cell-based model of spermatogenesis, we evaluated two major flame retardants, hexabromocyclododecane (HBCDD) and tetrabromobisphenol A (TBBPA), under acute conditions simulating occupational-level exposures. Here we show that HBCDD and TBBPA are human male reproductive toxicants in vitro. Although these toxicants do not specifically affect the survival of haploid spermatids, they affect spermatogonia and primary spermatocytes through mitochondrial membrane potential perturbation and reactive oxygen species generation, ultimately causing apoptosis. Taken together, these results show that HBCDD and TBBPA affect human spermatogenesis in vitro and potentially implicate this highly prevalent class of toxicants in the decline of Western males' sperm counts.
Collapse
Affiliation(s)
- Alyse N Steves
- Genetics and Molecular Biology Program, Laney Graduate School, Emory University, Atlanta, GA 30322, USA
| | - Joshua M Bradner
- Department of Environmental Health Science, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Kristen L Fowler
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA 30602, USA; Regenerative Bioscience Center, University of Georgia, Athens, GA 30602, USA
| | - Danielle Clarkson-Townsend
- Department of Environmental Health Science, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Brittany J Gill
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA 30602, USA; Regenerative Bioscience Center, University of Georgia, Athens, GA 30602, USA
| | - Adam C Turry
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA 30602, USA; Regenerative Bioscience Center, University of Georgia, Athens, GA 30602, USA
| | - W Michael Caudle
- Department of Environmental Health Science, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Gary W Miller
- Department of Environmental Health Science, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Anthony W S Chan
- Genetics and Molecular Biology Program, Laney Graduate School, Emory University, Atlanta, GA 30322, USA; Division of Neuropharmacology and Neurologic Diseases, Yerkes National Primate Research Center, GA 30322, USA; Department of Human Genetics, Emory University, Atlanta, GA 30322, USA
| | - Charles A Easley
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA 30602, USA; Regenerative Bioscience Center, University of Georgia, Athens, GA 30602, USA; Division of Neuropharmacology and Neurologic Diseases, Yerkes National Primate Research Center, GA 30322, USA.
| |
Collapse
|
11
|
Patel R, Bradner JM, Stout KA, Caudle WM. Alteration to Dopaminergic Synapses Following Exposure to Perfluorooctane Sulfonate (PFOS), in Vitro and in Vivo. Med Sci (Basel) 2016; 4:medsci4030013. [PMID: 29083377 PMCID: PMC5635798 DOI: 10.3390/medsci4030013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 08/04/2016] [Accepted: 08/09/2016] [Indexed: 12/30/2022] Open
Abstract
Our understanding of the contribution exposure to environmental toxicants has on neurological disease continues to evolve. Of these, Parkinson’s disease (PD) has been shown to have a strong environmental component to its etiopathogenesis. However, work is still needed to identify and characterize environmental chemicals that could alter the expression and function of the nigrostriatal dopamine system. Of particular interest is the neurotoxicological effect of perfluorinated compounds, such as perfluorooctane sulfonate (PFOS), which has been demonstrated to alter aspects of dopamine signaling. Using in vitro approaches, we have elaborated these initial findings to demonstrate the neurotoxicity of PFOS to the SH-SY5Y neuroblastoma cell line and dopaminergic primary cultured neurons. Using an in vivo model, we did not observe a deficit to dopaminergic terminals in the striatum of mice exposed to 10 mg/kg PFOS for 14 days. However, subsequent exposure to the selective dopaminergic neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) significantly reduced the expression of dopamine transporter (DAT) and tyrosine hydroxylase (TH), and resulted in an even greater reduction in DAT expression in animals previously exposed to PFOS. These findings suggest that PFOS is neurotoxic to the nigrostriatal dopamine circuit and this neurotoxicity could prime the dopamine terminal to more extensive damage following additional toxicological insults.
Collapse
Affiliation(s)
- Rahul Patel
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA.
| | - Joshua M Bradner
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA.
- Center for Neurodegenerative Disease, School of Medicine, Emory University, Atlanta, GA 30322, USA.
| | - Kristen A Stout
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA.
- Center for Neurodegenerative Disease, School of Medicine, Emory University, Atlanta, GA 30322, USA.
| | - William Michael Caudle
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA.
- Center for Neurodegenerative Disease, School of Medicine, Emory University, Atlanta, GA 30322, USA.
| |
Collapse
|
12
|
Genskow KR, Bradner JM, Hossain MM, Richardson JR, Caudle WM. Selective damage to dopaminergic transporters following exposure to the brominated flame retardant, HBCDD. Neurotoxicol Teratol 2015; 52:162-9. [PMID: 26073293 DOI: 10.1016/j.ntt.2015.06.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2015] [Revised: 06/05/2015] [Accepted: 06/09/2015] [Indexed: 12/01/2022]
Abstract
Over the last several decades, the use of halogenated organic compounds has become the cause of environmental and human health concerns. Of particular notoriety has been the establishment of the neurotoxicity of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). The subsequent banning of PBDEs has led to greatly increased use of 1,2,5,6,9,10-hexabromocyclododecane (HBCDD, also known as HBCD) as a flame retardant in consumer products. The physiochemical similarities between HBCDD and PBDEs suggest that HBCDD may also be neurotoxic to the dopamine system, which is specifically damaged in Parkinson disease (PD). The purpose of this study was to assess the neurotoxicity of HBCDD on the nigrostriatal dopamine system using an in vitro and in vivo approach. We demonstrate that exposure to HBCDD (0-25 μM) for 24 h causes significant cell death in the SK-N-SH catecholaminergic cell line, as well as reductions in the growth and viability of TH+ primary cultured neurons at lower concentrations (0-10 μM) after 72 h of treatment. Assessment of the in vivo neurotoxicity of HBCDD (25 mg/kg for 30 days) resulted in significant reductions in the expression of the striatal dopamine transporter and vesicular monoamine transporter 2, both of which are integral in mediating dopamine homeostasis and neurotransmission in the dopamine circuit. However, no changes were seen in the expression of tyrosine hydroxylase in the dopamine terminal, or striatal levels of dopamine. To date, these are the first data to demonstrate that exposure to HBCDD disrupts the nigrostriatal dopamine system. Given these results and the ubiquitous nature of HBCDD in the environment, its possible role as an environmental risk factor for PD should be further investigated.
Collapse
Affiliation(s)
- Kelly R Genskow
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322-3090, USA
| | - Joshua M Bradner
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322-3090, USA; Center for Neurodegenerative Disease, School of Medicine, Emory University, Atlanta, GA 30322-3090, USA
| | - Muhammad M Hossain
- Department of Environmental and Occupational Medicine, Robert Wood Johnson Medical School Piscataway, NJ 08854, USA
| | - Jason R Richardson
- Department of Environmental and Occupational Medicine, Robert Wood Johnson Medical School Piscataway, NJ 08854, USA
| | - W Michael Caudle
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322-3090, USA; Center for Neurodegenerative Disease, School of Medicine, Emory University, Atlanta, GA 30322-3090, USA.
| |
Collapse
|
13
|
Easley CA, Bradner JM, Moser A, Rickman CA, McEachin ZT, Merritt MM, Hansen JM, Caudle WM. Assessing reproductive toxicity of two environmental toxicants with a novel in vitro human spermatogenic model. Stem Cell Res 2015; 14:347-55. [PMID: 25863443 DOI: 10.1016/j.scr.2015.03.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 03/16/2015] [Accepted: 03/17/2015] [Indexed: 11/26/2022] Open
Abstract
Environmental influences and insults by reproductive toxicant exposure can lead to impaired spermatogenesis or infertility. Understanding how toxicants disrupt spermatogenesis is critical for determining how environmental factors contribute to impaired fertility. While current animal models are available, understanding of the reproductive toxic effects on human fertility requires a more robust model system. We recently demonstrated that human pluripotent stem cells can differentiate into spermatogonial stem cells/spermatogonia, primary and secondary spermatocytes, and haploid spermatids; a model that mimics many aspects of human spermatogenesis. Here, using this model system, we examine the effects of 2-bromopropane (2-BP) and 1,2,dibromo-3-chloropropane (DBCP) on in vitro human spermatogenesis. 2-BP and DBCP are non-endocrine disrupting toxicants that are known to impact male fertility. We show that acute treatment with either 2-BP or DBCP induces a reduction in germ cell viability through apoptosis. 2-BP and DBCP affect viability of different cell populations as 2-BP primarily reduces spermatocyte viability, whereas DBCP exerts a much greater effect on spermatogonia. Acute treatment with 2-BP or DBCP also reduces the percentage of haploid spermatids. Both 2-BP and DBCP induce reactive oxygen species (ROS) formation leading to an oxidized cellular environment. Taken together, these results suggest that acute exposure with 2-BP or DBCP causes human germ cell death in vitro by inducing ROS formation. This system represents a unique platform for assessing human reproductive toxicity potential of various environmental toxicants in a rapid, efficient, and unbiased format.
Collapse
Affiliation(s)
- Charles A Easley
- Laboratory of Translational Cell Biology, Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
| | - Joshua M Bradner
- Department of Environmental Health, Rollins School of Public Heath, Emory University, Atlanta, GA 30322, USA; Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Amber Moser
- Laboratory of Translational Cell Biology, Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Chelsea A Rickman
- Laboratory of Translational Cell Biology, Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Zachary T McEachin
- Laboratory of Translational Cell Biology, Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; Wallace H. Coulter Department of Biomedical Engineering, Georgia Tech College of Engineering, Atlanta, GA 30332, USA
| | - Megan M Merritt
- Laboratory of Translational Cell Biology, Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Jason M Hansen
- Division of Pulmonology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - W Michael Caudle
- Department of Environmental Health, Rollins School of Public Heath, Emory University, Atlanta, GA 30322, USA; Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA 30322, USA
| |
Collapse
|
14
|
Wilson WW, Onyenwe W, Bradner JM, Nennig SE, Caudle WM. Developmental exposure to the organochlorine insecticide endosulfan alters expression of proteins associated with neurotransmission in the frontal cortex. Synapse 2014; 68:485-97. [PMID: 25042905 DOI: 10.1002/syn.21764] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 06/11/2014] [Indexed: 11/11/2022]
Abstract
Exposure to environmental contaminants, such as organochlorine insecticides during critical periods of neurodevelopment has been shown to be a major contributor to several neuropsychological deficits seen in children, adolescence, and adults. Although the neurobehavioral outcomes resulting from exposure to these compounds are known the neurotransmitter circuitry and molecular targets that mediate these endpoints have not been identified. Given the importance of the frontal cortex in facilitating numerous neuropsychological processes, our current study sought to investigate the effects of developmental exposure to the organochlorine insecticide, endosulfan, on the expression of specific proteins associated with neurotransmission in the frontal cortex. Utilizing in vitro models we were able to show endosulfan reduces cell viability in IMR-32 neuroblastoma cells in addition to reducing synaptic puncta and neurite outgrowth in primary cultured neurons isolated from the frontal cortex of mice. Elaborating these findings to an in vivo model we found that developmental exposure of female mice to endosulfan during gestation and lactation elicited significant alterations to the GABAergic (GAT1, vGAT, GABAA receptor), glutamatergic (vGlut and GluN2B receptor), and dopaminergic (DAT, TH, VMAT2, and D2 receptor) neurotransmitter systems in the frontal cortex of male offspring. These findings identify damage to critical neurotransmitter circuits and proteins in the frontal cortex, which may underlie the neurobehavioral deficits observed following developmental exposure to endosulfan and other organochlorine insecticides.
Collapse
Affiliation(s)
- W Wyatt Wilson
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, 30322-3090
| | | | | | | | | |
Collapse
|
15
|
Bradner JM, Suragh TA, Wilson WW, Lazo CR, Stout KA, Kim HM, Wang MZ, Walker DI, Pennell KD, Richardson JR, Miller GW, Caudle WM. Exposure to the polybrominated diphenyl ether mixture DE-71 damages the nigrostriatal dopamine system: role of dopamine handling in neurotoxicity. Exp Neurol 2012; 241:138-47. [PMID: 23287494 DOI: 10.1016/j.expneurol.2012.12.013] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 12/13/2012] [Accepted: 12/18/2012] [Indexed: 11/26/2022]
Abstract
In the last several decades polybrominated diphenyl ethers (PBDEs) have replaced the previously banned polychlorinated biphenyls (PCBs) in multiple flame retardant utilities. As epidemiological and laboratory studies have suggested PCBs as a risk factor for Parkinson's disease (PD), the similarities between PBDEs and PCBs suggest that PBDEs have the potential to be neurotoxic to the dopamine system. The purpose of this study was to evaluate the neurotoxic effects of the PBDE mixture, DE-71, on the nigrostriatal dopamine system and address the role of altered dopamine handling in mediating this neurotoxicity. Using an in vitro model system we found DE-71 effectively caused cell death in a dopaminergic cell line as well as reducing the number of TH+ neurons isolated from VMAT2 WT and LO animals. Assessment of DE-71 neurotoxicity in vivo demonstrated significant deposition of PBDE congeners in the brains of mice, leading to reductions in striatal dopamine and dopamine handling, as well as reductions in the striatal dopamine transporter (DAT) and VMAT2. Additionally, DE-71 elicited a significant locomotor deficit in the VMAT2 WT and LO mice. However, no change was seen in TH expression in dopamine terminal or in the number of dopamine neurons in the substantia nigra pars compacta (SNpc). To date, these are the first data to demonstrate that exposure to PBDEs disrupts the nigrostriatal dopamine system. Given their similarities to PCBs, additional laboratory and epidemiological research should be considered to assess PBDEs as a potential risk factor for PD and other neurological disorders.
Collapse
Affiliation(s)
- Joshua M Bradner
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322-3090, USA.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Serluca FC, Xu B, Okabe N, Baker K, Lin SY, Sullivan-Brown J, Konieczkowski DJ, Jaffe KM, Bradner JM, Fishman MC, Burdine RD. Mutations in zebrafish leucine-rich repeat-containing six-like affect cilia motility and result in pronephric cysts, but have variable effects on left-right patterning. Development 2009; 136:1621-31. [PMID: 19395640 DOI: 10.1242/dev.020735] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Cilia defects have been implicated in a variety of human diseases and genetic disorders, but how cilia motility contributes to these phenotypes is still unknown. To further our understanding of how cilia function in development, we have cloned and characterized two alleles of seahorse, a zebrafish mutation that results in pronephric cysts. seahorse encodes Lrrc6l, a leucine-rich repeat-containing protein that is highly conserved in organisms that have motile cilia. seahorse is expressed in zebrafish tissues known to contain motile cilia. Although mutants do not affect cilia structure and retain the ability to interact with Disheveled, both alleles of seahorse strongly affect cilia motility in the zebrafish pronephros and neural tube. Intriguingly, although seahorse mutations variably affect fluid flow in Kupffer's vesicle, they can have very weak effects on left-right patterning. Combined with recently published results, our alleles suggest that the function of seahorse in cilia motility is separable from its function in other cilia-related phenotypes.
Collapse
|