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Rodriguez P, Blakely RD. Sink or swim: Does a worm paralysis phenotype hold clues to neurodegenerative disease? J Cell Physiol 2024; 239:e31125. [PMID: 37795580 DOI: 10.1002/jcp.31125] [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: 07/15/2023] [Revised: 09/07/2023] [Accepted: 09/11/2023] [Indexed: 10/06/2023]
Abstract
Receiving a neurodegenerative disease (NDD) diagnosis, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, or amyotrophic lateral sclerosis, is devastating, particularly given the limited options for treatment. Advances in genetic technologies have allowed for efficient modeling of NDDs in animals and brought hope for new disease-modifying medications. The complexity of the mammalian brain and the costs and time needed to identify and develop therapeutic leads limits progress. Modeling NDDs in invertebrates, such as the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans, offers orders of magnitude increases in speed of genetic analysis and manipulation, and can be pursued at substantially reduced cost, providing an important, platform complement and inform research with mammalian NDD models. In this review, we describe how our efforts to exploit C. elegans for the study of neural signaling and health led to the discovery of a paralytic phenotype (swimming-induced paralysis) associated with altered dopamine signaling and, surprisingly, to the discovery of a novel gene and pathway whose dysfunction in glial cells triggers neurodegeneration. Research to date on swip-10 and its putative mammalian ortholog MBLAC1, suggests that a tandem analysis will offer insights into NDD mechanisms and insights into novel, disease-modifying therapeutics.
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Affiliation(s)
- Peter Rodriguez
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Boca Raton, Florida, USA
| | - Randy D Blakely
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Boca Raton, Florida, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida, USA
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Refai O, Aggarwal S, Cheng MH, Gichi Z, Salvino JM, Bahar I, Blakely RD, Mortensen OV. Allosteric Modulator KM822 Attenuates Behavioral Actions of Amphetamine in Caenorhabditis elegans through Interactions with the Dopamine Transporter DAT-1. Mol Pharmacol 2022; 101:123-131. [PMID: 34906999 PMCID: PMC8969146 DOI: 10.1124/molpharm.121.000400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 12/03/2021] [Indexed: 11/22/2022] Open
Abstract
Aberrant dopamine (DA) signaling is associated with several psychiatric disorders, such as autism, bipolar disorder, addiction, and Parkinson's disease, and several medications that target the DA transporter (DAT) can induce or treat these disorders. In addition, psychostimulants, such as cocaine and D-amphetamine (AMPH), rely on the competitive interactions with the transporter's substrate binding site to produce their rewarding effects. Agents that exhibit noncompetitive, allosteric modulation of DAT remain an important topic of investigation due to their potential therapeutic applications. We previously identified a novel allosteric modulator of human DAT, KM822, that can decrease the affinity of cocaine for DAT and attenuate cocaine-elicited behaviors; however, whether DAT is the sole mediator of KM822 actions in vivo is unproven given the large number of potential off-target sites. Here, we provide in silico and in vitro evidence that the allosteric site engaged by KM822 is conserved between human DAT and Caenorhabditis elegans DAT-1. KM822 binds to a similar pocket in DAT-1 as previously identified in human DAT. In functional dopamine uptake assays, KM822 affects the interaction between AMPH and DAT-1 by reducing the affinity of AMPH for DAT-1. Finally, through a combination of genetic and pharmacological in vivo approaches we provide evidence that KM822 diminishes the behavioral actions of AMPH on swimming-induced paralysis through a direct allosteric modulation of DAT-1. More broadly, our findings demonstrate allosteric modulation of DAT as a behavior modifying strategy and suggests that Caenorhabditis elegans can be operationalized to identify and investigate the interactions of DAT allosteric modulators. SIGNIFICANCE STATEMENT: We previously demonstrated that the dopamine transporter (DAT) allosteric modulator KM822 decreases cocaine affinity for human DAT. Here, using in silico and in vivo genetic approaches, we extend this finding to interactions with amphetamine, demonstrating evolutionary conservation of the DAT allosteric site. In Caenorhabditis elegans, we report that KM822 suppresses amphetamine behavioral effects via specific interactions with DAT-1. Our findings reveal Caenorhabditis elegans as a new tool to study allosteric modulation of DAT and its behavioral consequences.
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Affiliation(s)
- Osama Refai
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, Florida (O.R., Z.G., R.D.B.); Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida (O.R., R.D.B.); Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania (S.A., O.V.M.); Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania (M.H.C., I.B.); and The Wistar Institute, Philadelphia, Pennsylvania (J.M.S.)
| | - Shaili Aggarwal
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, Florida (O.R., Z.G., R.D.B.); Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida (O.R., R.D.B.); Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania (S.A., O.V.M.); Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania (M.H.C., I.B.); and The Wistar Institute, Philadelphia, Pennsylvania (J.M.S.)
| | - Mary Hongying Cheng
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, Florida (O.R., Z.G., R.D.B.); Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida (O.R., R.D.B.); Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania (S.A., O.V.M.); Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania (M.H.C., I.B.); and The Wistar Institute, Philadelphia, Pennsylvania (J.M.S.)
| | - Zayna Gichi
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, Florida (O.R., Z.G., R.D.B.); Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida (O.R., R.D.B.); Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania (S.A., O.V.M.); Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania (M.H.C., I.B.); and The Wistar Institute, Philadelphia, Pennsylvania (J.M.S.)
| | - Joseph M Salvino
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, Florida (O.R., Z.G., R.D.B.); Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida (O.R., R.D.B.); Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania (S.A., O.V.M.); Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania (M.H.C., I.B.); and The Wistar Institute, Philadelphia, Pennsylvania (J.M.S.)
| | - Ivet Bahar
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, Florida (O.R., Z.G., R.D.B.); Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida (O.R., R.D.B.); Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania (S.A., O.V.M.); Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania (M.H.C., I.B.); and The Wistar Institute, Philadelphia, Pennsylvania (J.M.S.)
| | - Randy D Blakely
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, Florida (O.R., Z.G., R.D.B.); Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida (O.R., R.D.B.); Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania (S.A., O.V.M.); Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania (M.H.C., I.B.); and The Wistar Institute, Philadelphia, Pennsylvania (J.M.S.)
| | - Ole V Mortensen
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, Florida (O.R., Z.G., R.D.B.); Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida (O.R., R.D.B.); Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania (S.A., O.V.M.); Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania (M.H.C., I.B.); and The Wistar Institute, Philadelphia, Pennsylvania (J.M.S.)
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Formisano R, Rosikon KD, Singh A, Dhillon HS. The dopamine membrane transporter plays an active modulatory role in synaptic dopamine homeostasis. J Neurosci Res 2021; 100:1551-1559. [PMID: 34747520 PMCID: PMC9079189 DOI: 10.1002/jnr.24965] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 08/17/2021] [Accepted: 08/29/2021] [Indexed: 11/11/2022]
Abstract
Modulatory mechanisms of neurotransmitter release and clearance are highly controlled processes whose finely tuned regulation is critical for functioning of the nervous system. Dysregulation of the monoamine neurotransmitter dopamine can lead to several neuropathies. Synaptic modulation of dopamine is known to involve pre-synaptic D2 auto-receptors and acid sensing ion channels. In addition, the dopamine membrane transporter (DAT), which is responsible for clearance of dopamine from the synaptic cleft, is suspected to play an active role in modulating release of dopamine. Using functional imaging on the Caenorhabditis elegans model system, we show that DAT-1 acts as a negative feedback modulator to neurotransmitter vesicle fusion. Results from our fluorescence recovery after photo-bleaching (FRAP) based experiments were followed up with and reaffirmed using swimming-induced paralysis behavioral assays. Utilizing our numerical FRAP data we have developed a mechanistic model to dissect the dynamics of synaptic vesicle fusion, and compare the feedback effects of DAT-1 with the dopamine auto-receptor. Our experimental results and the mechanistic model are of potential broader significance, as similar dynamics are likely to be used by other synaptic modulators including membrane transporters for other neurotransmitters across species.
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Affiliation(s)
- Rosaria Formisano
- Department of Biological Sciences, Delaware Center for Neuroscience Research, Delaware State University, Dover, DE, USA
| | - Katarzyna D Rosikon
- Department of Biological Sciences, Delaware Center for Neuroscience Research, Delaware State University, Dover, DE, USA
| | - Abhyudai Singh
- Department of Electrical and Computer Engineering, Biomedical Engineering, Data Sciences Institute, University of Delaware, Newark, DE, USA
| | - Harbinder S Dhillon
- Department of Biological Sciences, Delaware Center for Neuroscience Research, Delaware State University, Dover, DE, USA
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Raj V, Nair A, Thekkuveettil A. Manganese exposure during early larval stages of C. elegans causes learning disability in the adult stage. Biochem Biophys Res Commun 2021; 568:89-94. [PMID: 34198165 DOI: 10.1016/j.bbrc.2021.06.073] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 06/22/2021] [Indexed: 11/29/2022]
Abstract
Manganese (Mn), even though an essential trace element, causes neurotoxicity in excess. In adults, over-exposure to Mn causes clinical manifestations, including dystonia, progressive bradykinesia, disturbance of gait, slurring, and stuttering of speech. These symptoms are mainly because of Mn-associated oxidative stress and degeneration of dopamine neurons in the central nervous system. Children with excessive Mn exposure often show learning disabilities but rarely show symptoms associated with dopaminergic neuron dysfunction. It is unclear why Mn exposure shows distinctive clinical outcomes in developing brains versus adult brains. Studies on nematode C. elegans have demonstrated that it is an excellent model to elucidate Mn-associated toxicity in the nervous system. In this study, we chronically exposed Mn to L1 larval stage of the worms to understand the effects on dopamine neurons and cognitive development. The worms showed modified behavior to exogenous dopamine compared to the control. The dopamine neurons showed resistance to neurodegeneration on repeated Mn exposure during the adult stage. As observed in mammalian systems, these worms showed significantly low olfactory adaptive learning and memory. This study shows that C. elegans alters adaptive developmental plasticity during Mn overexposure, modifying its sensitivity towards the metal ion and leads to remodeling in its innate learning behavior.
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Affiliation(s)
- Vishnu Raj
- Division of Molecular Medicine, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, 695012, India
| | - Agrima Nair
- Division of Molecular Medicine, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, 695012, India
| | - Anoopkumar Thekkuveettil
- Division of Molecular Medicine, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, 695012, India.
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