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Wang J, Barr MM, Wehman AM. Extracellular vesicles. Genetics 2024:iyae088. [PMID: 38884207 DOI: 10.1093/genetics/iyae088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Accepted: 05/21/2024] [Indexed: 06/18/2024] Open
Abstract
Extracellular vesicles (EVs) encompass a diverse array of membrane-bound organelles released outside cells in response to developmental and physiological cell needs. EVs play important roles in remodeling the shape and content of differentiating cells and can rescue damaged cells from toxic or dysfunctional content. EVs can send signals and transfer metabolites between tissues and organisms to regulate development, respond to stress or tissue damage, or alter mating behaviors. While many EV functions have been uncovered by characterizing ex vivo EVs isolated from body fluids and cultured cells, research using the nematode Caenorhabditis elegans has provided insights into the in vivo functions, biogenesis, and uptake pathways. The C. elegans EV field has also developed methods to analyze endogenous EVs within the organismal context of development and adult physiology in free-living, behaving animals. In this review, we summarize major themes that have emerged for C. elegans EVs and their relevance to human health and disease. We also highlight the diversity of biogenesis mechanisms, locations, and functions of worm EVs and discuss open questions and unexplored topics tenable in C. elegans, given the nematode model is ideal for light and electron microscopy, genetic screens, genome engineering, and high-throughput omics.
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Affiliation(s)
- Juan Wang
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ 08854, USA
| | - Maureen M Barr
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ 08854, USA
| | - Ann M Wehman
- Department of Biological Sciences, University of Denver, Denver, CO 80210, USA
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2
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Clark AS, Kalmanson Z, Morton K, Hartman J, Meyer J, San-Miguel A. An unbiased, automated platform for scoring dopaminergic neurodegeneration in C. elegans. PLoS One 2023; 18:e0281797. [PMID: 37418455 PMCID: PMC10328331 DOI: 10.1371/journal.pone.0281797] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 06/20/2023] [Indexed: 07/09/2023] Open
Abstract
Caenorhabditis elegans (C. elegans) has served as a simple model organism to study dopaminergic neurodegeneration, as it enables quantitative analysis of cellular and sub-cellular morphologies in live animals. These isogenic nematodes have a rapid life cycle and transparent body, making high-throughput imaging and evaluation of fluorescently tagged neurons possible. However, the current state-of-the-art method for quantifying dopaminergic degeneration requires researchers to manually examine images and score dendrites into groups of varying levels of neurodegeneration severity, which is time consuming, subject to bias, and limited in data sensitivity. We aim to overcome the pitfalls of manual neuron scoring by developing an automated, unbiased image processing algorithm to quantify dopaminergic neurodegeneration in C. elegans. The algorithm can be used on images acquired with different microscopy setups and only requires two inputs: a maximum projection image of the four cephalic neurons in the C. elegans head and the pixel size of the user's camera. We validate the platform by detecting and quantifying neurodegeneration in nematodes exposed to rotenone, cold shock, and 6-hydroxydopamine using 63x epifluorescence, 63x confocal, and 40x epifluorescence microscopy, respectively. Analysis of tubby mutant worms with altered fat storage showed that, contrary to our hypothesis, increased adiposity did not sensitize to stressor-induced neurodegeneration. We further verify the accuracy of the algorithm by comparing code-generated, categorical degeneration results with manually scored dendrites of the same experiments. The platform, which detects 20 different metrics of neurodegeneration, can provide comparative insight into how each exposure affects dopaminergic neurodegeneration patterns.
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Affiliation(s)
- Andrew S. Clark
- Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Zachary Kalmanson
- Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Katherine Morton
- Nicholas School of the Environment, Duke University, Durham, North Carolina, United States of America
| | - Jessica Hartman
- Nicholas School of the Environment, Duke University, Durham, North Carolina, United States of America
- Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Joel Meyer
- Nicholas School of the Environment, Duke University, Durham, North Carolina, United States of America
| | - Adriana San-Miguel
- Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, United States of America
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Melnikov K, Kucharíková S, Bárdyová Z, Botek N, Kaiglová A. Applications of a powerful model organism Caenorhabditis elegans to study the neurotoxicity induced by heavy metals and pesticides. Physiol Res 2023; 72:149-166. [PMID: 37159850 PMCID: PMC10226405 DOI: 10.33549/physiolres.934977] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 02/03/2023] [Indexed: 08/27/2023] Open
Abstract
The expansion of industry and the use of pesticides in agriculture represent one of the major causes of environmental contamination. Unfortunately, individuals and animals are exposed to these foreign and often toxic substances on a daily basis. Therefore, it is crucial to monitor the impact of such chemicals on human health. Several in vitro studies have addressed this issue, but it is difficult to explore the impact of these compounds on living organisms. A nematode Caenorhabditis elegans has become a useful alternative to animal models mainly because of its transparent body, fast growth, short life cycle, and easy cultivation. Furthermore, at the molecular level, there are significant similarities between humans and C. elegans. These unique features make it an excellent model to complement mammalian models in toxicology research. Heavy metals and pesticides, which are considered environmental contaminants, are known to have affected the locomotion, feeding behavior, brood size, growth, life span, and cell death of C. elegans. Today, there are increasing numbers of research articles dedicated to this topic, of which we summarized the most recent findings dedicated to the effect of heavy metals, heavy metal mixtures, and pesticides on the well-characterized nervous system of this nematode.
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Affiliation(s)
- K Melnikov
- Department of Laboratory Medicine, Faculty of Health Care and Social Work, University in Trnava, Slovakia.
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Clark AS, Kalmanson Z, Morton K, Hartman J, Meyer J, San-Miguel A. An unbiased, automated platform for scoring dopaminergic neurodegeneration in C. elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.02.526781. [PMID: 36778421 PMCID: PMC9915681 DOI: 10.1101/2023.02.02.526781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Caenorhabditis elegans ( C. elegans ) has served as a simple model organism to study dopaminergic neurodegeneration, as it enables quantitative analysis of cellular and sub-cellular morphologies in live animals. These isogenic nematodes have a rapid life cycle and transparent body, making high-throughput imaging and evaluation of fluorescently tagged neurons possible. However, the current state-of-the-art method for quantifying dopaminergic degeneration requires researchers to manually examine images and score dendrites into groups of varying levels of neurodegeneration severity, which is time consuming, subject to bias, and limited in data sensitivity. We aim to overcome the pitfalls of manual neuron scoring by developing an automated, unbiased image processing algorithm to quantify dopaminergic neurodegeneration in C. elegans . The algorithm can be used on images acquired with different microscopy setups and only requires two inputs: a maximum projection image of the four cephalic neurons in the C. elegans head and the pixel size of the user’s camera. We validate the platform by detecting and quantifying neurodegeneration in nematodes exposed to rotenone, cold shock, and 6-hydroxydopamine using 63x epifluorescence, 63x confocal, and 40x epifluorescence microscopy, respectively. Analysis of tubby mutant worms with altered fat storage showed that, contrary to our hypothesis, increased adiposity did not sensitize to stressor-induced neurodegeneration. We further verify the accuracy of the algorithm by comparing code-generated, categorical degeneration results with manually scored dendrites of the same experiments. The platform, which detects 19 different metrics of neurodegeneration, can provide comparative insight into how each exposure affects dopaminergic neurodegeneration patterns.
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Affiliation(s)
- Andrew S Clark
- Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
| | - Zachary Kalmanson
- Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
| | - Katherine Morton
- Nicholas School of the Environment, Duke University, Durham, North Carolina, USA
| | - Jessica Hartman
- Nicholas School of the Environment, Duke University, Durham, North Carolina, USA
- Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Joel Meyer
- Nicholas School of the Environment, Duke University, Durham, North Carolina, USA
| | - Adriana San-Miguel
- Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
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Ke T, Santamaria A, Junior FB, Rocha JBT, Bowman AB, Aschner M. Methylmercury exposure-induced reproductive effects are mediated by dopamine in Caenorhabditis elegans. Neurotoxicol Teratol 2022; 93:107120. [PMID: 35987454 DOI: 10.1016/j.ntt.2022.107120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 08/09/2022] [Accepted: 08/11/2022] [Indexed: 11/28/2022]
Abstract
Methylmercury (MeHg) is a neurotoxicant that exists in the natural environment, which level can be greatly increased because of human activity. MeHg exposures have the risk of being detrimental to the development of the nervous system. Studies on MeHg toxicity have largely focused on the mechanisms of its neurotoxicity following developmental exposures. Additionally, reproductive toxicity of developmental MeHg exposures has been noted in rodent models. The model organism Caenorhabditis elegans (C. elegans) is a self-fertilizing animal which has a short lifespan around 20 days. Most C. elegans are hermaphrodites that can generate both sperm and oocytes. To investigate the effects of developmental MeHg exposures on the reproduction in C. elegans, larvae stage 1 worms were exposed to MeHg (0, 0.01 or 0.05 μM) for 24 h. The laid eggs and oocytes were compared during each day at adult stages for 6 days. We showed that MeHg exposure significantly induced an increased number of eggs in day 1 adults without an effect on the timing of egg laying or the total number of eggs or oocytes over the 6-day period. The expression of dat-1 and cat-2 and dopamine levels were increased in worms exposed to MeHg. Supplementation with 100 μM dopamine recapitulated the effect of MeHg on the number of eggs present in day 1 adults. Furthermore, the effect of MeHg on the number of eggs was abrogated in the cat-2 mutant worms CB1112. The number of oocytes in the 6-day adult stages was decreased by MeHg in the dat-1 mutant RM2702. MeHg exposures did not change the mating rate or the number of offspring from mating. Combined, these novel findings show that developmental exposure to low levels of MeHg has limited effects on the reproduction in C. elegans. Furthermore, our data support a modulatory role of dopamine in MeHg-induced effects on reproduction in this model system.
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Affiliation(s)
- Tao Ke
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, United States
| | - Abel Santamaria
- Laboratorio de Aminoácidos Excitadores/Laboratorio de Neurofarmacología Molecular y Nanotecnología, Instituto Nacional de Neurología y Neurocirugía, 14269 Mexico City, Mexico
| | - Fernando Barbosa Junior
- Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP 14040-900, Brazil
| | - João B T Rocha
- Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, 97105900 Santa Maria, RS, Brazil
| | - Aaron B Bowman
- School of Health Sciences, Purdue University, West Lafayette, IN 47907-2051, United States
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, United States.
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The Human LRRK2 Modulates the Age-Dependent Effects of Developmental Methylmercury Exposure in Caenorhabditis elegans. Neurotox Res 2022; 40:1235-1247. [PMID: 35838907 DOI: 10.1007/s12640-022-00547-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 06/30/2022] [Accepted: 07/06/2022] [Indexed: 10/17/2022]
Abstract
Methylmercury (MeHg) neurotoxicity exhibits age-dependent effects with a latent and/or persistent neurotoxic effect on aged animals. Individual susceptibility to MeHg neurotoxicity is governed by both exposure duration and genetic factors that can magnify or mitigate the pathologic processes associated with this exposure. We previously showed the G2019S mutation of leucine-rich repeat kinase 2 (LRRK2) modulates the response of worms to high levels of MeHg, mitigating its effect on neuronal morphology in pre-vesicles in cephalic (CEP) dopaminergic neurons. Here we sought to better understand the long-term effects of MeHg exposure at low levels (100-fold lower than that in our previous report) and the modulatory role of the LRRK2 mutation. Worms exposed to MeHg (10 or 50 nM) at the larval stage (L1 stage) were compared at adult stages (young age: day 1 adult; middle age: day 5 adult; old age: day 10 adult) for the swimming speeds in M9 buffer, moving speeds during locomotion on an OP50-seeded plate, and the numbers of CEP dopaminergic pre-vesicles, vesicular structures originating from the dendrites of CEP for exportation of cellular content. In addition, the expression levels of Caenorhabditis elegans homologs of dopamine transporter (dat-1) and tyrosine hydroxylase (cat-2) were also analyzed at these adult stages. Our data showed that swimming speeds were reduced in wild-type worms at the day 10 adult stage at 50 nM MeHg level; yet, reduced swimming speeds were noted in the G2019S LRRK2 transgenic line upon MeHg exposures as low as 10 nM. Compared to locomotor speeds, swimming speeds appear to be more sensitive to the behavioral effects of developmental MeHg exposures, as the locomotor speeds were largely intact and indistinguishable from controls following MeHg exposures. Furthermore, we showed an age-dependent modulation of dat-1 and cat-2 expressions, which could also be modified by the LRRK2 mutation. Although MeHg exposures did not change the number of pre-vesicles, the LRRK2 mutation was associated with increased numbers of pre-vesicles in aged worms. Our data suggest that the latent behavioral effects of MeHg are sensitized by the G2019S LRRK2 mutation, and the underlying mechanism likely involves age-dependent changes in dopaminergic signaling.
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The Modulatory Role of sti-1 in Methylmercury-Induced Toxicity in Caenorhabditis elegans. Neurotox Res 2022; 40:837-846. [PMID: 35471723 DOI: 10.1007/s12640-022-00515-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 04/14/2022] [Accepted: 04/19/2022] [Indexed: 10/18/2022]
Abstract
Human exposure to the neurotoxin methylmercury (MeHg) poses a significant health risk to the development of the nervous system. The mechanisms of MeHg-induced neurotoxicity are associated with the disruption of cellular homeostasis, and include oxidative stress, loss of calcium homeostasis, and impaired protein quality control. The stress inducible protein 1 (STI-1) is involved in the regulation of protein quality control by acting as a protein cochaperone to maintain optimal protein unfolding and refolding. Here, we utilized the Caenorhabditis elegans (C. elegans) model of MeHg toxicity to characterize the role of the sti-1 gene in MeHg-induced toxicity. We showed that lifespan and developmental milestone timings were significantly altered in sti-1 knockout (KO) animals with MeHg exposure. However, knocking down sti-1 by RNAi did not result in an analogous effect for lifespan, but did still sensitize to delays in developmental milestone progression by acute MeHg, suggesting that insufficiency of sti-1 does not recapitulate all phenotypes of the null mutation. Furthermore, inhibition of ATP levels by MeHg exposure was modulated by sti-1. Considering that the skn-1/gst-4 pathway is highly involved in metal's toxicity, such pathway was also explored in our model. We showed that sti-1 mutant worms exhibited impaired capacity to upregulate the antioxidant genes skn-1/gst-4, highlighting a central role of sti-1 in modulating antioxidant response. Lastly, we showed that loss-of-function mutation in the rrf-3 gene, which encodes a putative RNA-directed RNA polymerase, has significant effect in altering MeHg-induced toxicity by potentiating the animal's detoxification system. Altogether, our novel data show an indispensable role of protein quality control in the defense against MeHg toxicity.
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Ke T, Tinkov AA, Skalny AV, Bowman AB, Rocha JBT, Santamaria A, Aschner M. Developmental exposure to methylmercury and ADHD, a literature review of epigenetic studies. ENVIRONMENTAL EPIGENETICS 2021; 7:dvab014. [PMID: 34881051 PMCID: PMC8648069 DOI: 10.1093/eep/dvab014] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 09/20/2021] [Accepted: 11/08/2021] [Indexed: 06/13/2023]
Abstract
Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that affects the competence of academic performance and social wellness in children and adults. The causes of ADHD are unclear. Both genetic and environmental factors contribute to the development of ADHD. The behavioral impairments in ADHD are associated with epigenetic changes in genes that are important for neurodevelopment. Among environmental causes of ADHD, the neurotoxin methylmercury (MeHg) is associated with an increased risk for ADHD. Developing children are susceptible to neurotoxic effects of prenatal MeHg exposure. Human epidemiology studies have shown that prenatal MeHg exposure could invoke epigenetic changes in genes that are involved in ADHD. In addition, the pathogenesis of ADHD involves dopaminergic system, which is a target of developmental MeHg exposure. MeHg-induced alterations in the dopaminergic system have a profound impact on behavioral functions in adults. As a trace level of MeHg (around nM) can induce long-lasting behavioral alterations, potential mechanisms of MeHg-induced functional changes in the dopaminergic system may involve epigenetic mechanisms. Here, we review the relevant evidence on developmental MeHg exposures and the risk for ADHD. We also point out research gaps in understanding environmental causes of ADHD.
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Affiliation(s)
- Tao Ke
- **Correspondence address. Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Forchheimer Building, Room 209, Bronx, NY 10461, USA. Tel: +1 718 430 4047; Fax: +1 718 430 8922; E-mail:
| | - Alexey A Tinkov
- World-Class Research Center “Digital Biodesign and Personalized Healthcare”, IM Sechenov First Moscow State Medical University (Sechenov University), Moscow 119435, Russia
- Laboratory of Ecobiomonitoring and Quality Control, Yaroslavl State University, Yaroslavl 150003, Russia
| | - Antoly V Skalny
- World-Class Research Center “Digital Biodesign and Personalized Healthcare”, IM Sechenov First Moscow State Medical University (Sechenov University), Moscow 119435, Russia
- Laboratory of Medical Elementology, K.G. Razumovsky Moscow State University of Technologies and Management, Moscow 109004, Russia
| | - Aaron B Bowman
- School of Health Sciences, Purdue University, West Lafayette, IN 47907-2051, USA
| | - Joao B T Rocha
- Department of Biochemistry and Molecular Biology, Federal University of Santa Maria, Santa Maria, RS 97105-900, Brazil
| | - Abel Santamaria
- Laboratorio de Aminoácidos Excitadores, Instituto Nacional de Neurología y Neurocirugía, Mexico City 14269, Mexico
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Forchheimer Building, Room 209, Bronx, NY 10461, USA
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Martins AC, Ke T, Bowman AB, Aschner M. New insights on mechanisms underlying methylmercury-induced and manganese-induced neurotoxicity. CURRENT OPINION IN TOXICOLOGY 2021; 25:30-35. [PMID: 33898886 PMCID: PMC8061890 DOI: 10.1016/j.cotox.2021.03.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Toxic and essential elements are widely distributed in the Earth's crust and individuals may be exposed to several of them. Indeed, exposure to toxic elements such as mercury (Hg) can be a potential health risk factor of health, mainly by ingestion of fish containing methylmercury (MeHg). On the other hand, essential elements such as manganese (Mn) play an important role in physiological process in human body. However, Mn overexposure may cause toxic effects. In this respect, the neurotoxic effects of MeHg and Mn on the developing brain are well recognized. Therefore, in this critical review, we address the effects of MeHg and Mn on cell signaling pathways which may contribute to molecular mechanisms involved in MeHg- and Mn-induced neurotoxicity.
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Affiliation(s)
- Airton C Martins
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Tao Ke
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Aaron B Bowman
- School of Health Sciences, Purdue University, West Lafayette, IN, USA
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
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