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Belcher S, Flores-Iga G, Natarajan P, Crummett G, Talavera-Caro A, Gracia-Rodriguez C, Lopez-Ortiz C, Das A, Adjeroh DA, Nimmakayala P, Balagurusamy N, Reddy UK. Dietary Curcumin Intake and Its Effects on the Transcriptome and Metabolome of Drosophila melanogaster. Int J Mol Sci 2024; 25:6559. [PMID: 38928266 PMCID: PMC11203963 DOI: 10.3390/ijms25126559] [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: 05/01/2024] [Revised: 06/01/2024] [Accepted: 06/11/2024] [Indexed: 06/28/2024] Open
Abstract
Curcumin, a polyphenol derived from Curcuma longa, used as a dietary spice, has garnered attention for its therapeutic potential, including antioxidant, anti-inflammatory, and antimicrobial properties. Despite its known benefits, the precise mechanisms underlying curcumin's effects on consumers remain unclear. To address this gap, we employed the genetic model Drosophila melanogaster and leveraged two omics tools-transcriptomics and metabolomics. Our investigation revealed alterations in 1043 genes and 73 metabolites upon supplementing curcumin into the diet. Notably, we observed genetic modulation in pathways related to antioxidants, carbohydrates, and lipids, as well as genes associated with gustatory perception and reproductive processes. Metabolites implicated in carbohydrate metabolism, amino acid biosynthesis, and biomarkers linked to the prevention of neurodegenerative diseases such as schizophrenia, Alzheimer's, and aging were also identified. The study highlighted a strong correlation between the curcumin diet, antioxidant mechanisms, and amino acid metabolism. Conversely, a lower correlation was observed between carbohydrate metabolism and cholesterol biosynthesis. This research highlights the impact of curcumin on the diet, influencing perception, fertility, and molecular wellness. Furthermore, it directs future studies toward a more focused exploration of the specific effects of curcumin consumption.
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Affiliation(s)
- Samantha Belcher
- Department of Biology, Gus R. Douglass Institute, West Virginia State University, Institute, WV 25112, USA; (S.B.); (G.F.-I.); (P.N.); (G.C.); (A.T.-C.); (C.G.-R.); (C.L.-O.); (A.D.); (P.N.)
| | - Gerardo Flores-Iga
- Department of Biology, Gus R. Douglass Institute, West Virginia State University, Institute, WV 25112, USA; (S.B.); (G.F.-I.); (P.N.); (G.C.); (A.T.-C.); (C.G.-R.); (C.L.-O.); (A.D.); (P.N.)
| | - Purushothaman Natarajan
- Department of Biology, Gus R. Douglass Institute, West Virginia State University, Institute, WV 25112, USA; (S.B.); (G.F.-I.); (P.N.); (G.C.); (A.T.-C.); (C.G.-R.); (C.L.-O.); (A.D.); (P.N.)
| | - Garrett Crummett
- Department of Biology, Gus R. Douglass Institute, West Virginia State University, Institute, WV 25112, USA; (S.B.); (G.F.-I.); (P.N.); (G.C.); (A.T.-C.); (C.G.-R.); (C.L.-O.); (A.D.); (P.N.)
| | - Alicia Talavera-Caro
- Department of Biology, Gus R. Douglass Institute, West Virginia State University, Institute, WV 25112, USA; (S.B.); (G.F.-I.); (P.N.); (G.C.); (A.T.-C.); (C.G.-R.); (C.L.-O.); (A.D.); (P.N.)
| | - Celeste Gracia-Rodriguez
- Department of Biology, Gus R. Douglass Institute, West Virginia State University, Institute, WV 25112, USA; (S.B.); (G.F.-I.); (P.N.); (G.C.); (A.T.-C.); (C.G.-R.); (C.L.-O.); (A.D.); (P.N.)
- Laboratorio de Biorremediación, Facultad de Ciencias Biológicas, Universidad Autónoma de Coahuila, Torreón 27275, Coahuila, Mexico
| | - Carlos Lopez-Ortiz
- Department of Biology, Gus R. Douglass Institute, West Virginia State University, Institute, WV 25112, USA; (S.B.); (G.F.-I.); (P.N.); (G.C.); (A.T.-C.); (C.G.-R.); (C.L.-O.); (A.D.); (P.N.)
| | - Amartya Das
- Department of Biology, Gus R. Douglass Institute, West Virginia State University, Institute, WV 25112, USA; (S.B.); (G.F.-I.); (P.N.); (G.C.); (A.T.-C.); (C.G.-R.); (C.L.-O.); (A.D.); (P.N.)
| | - Donald A. Adjeroh
- Lane Department of Computer Science and Electrical Engineering, West Virginia University, Morgantown, WV 26506, USA;
| | - Padma Nimmakayala
- Department of Biology, Gus R. Douglass Institute, West Virginia State University, Institute, WV 25112, USA; (S.B.); (G.F.-I.); (P.N.); (G.C.); (A.T.-C.); (C.G.-R.); (C.L.-O.); (A.D.); (P.N.)
| | - Nagamani Balagurusamy
- Laboratorio de Biorremediación, Facultad de Ciencias Biológicas, Universidad Autónoma de Coahuila, Torreón 27275, Coahuila, Mexico
| | - Umesh K. Reddy
- Department of Biology, Gus R. Douglass Institute, West Virginia State University, Institute, WV 25112, USA; (S.B.); (G.F.-I.); (P.N.); (G.C.); (A.T.-C.); (C.G.-R.); (C.L.-O.); (A.D.); (P.N.)
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Her Y, Pascual DM, Goldstone-Joubert Z, Marcogliese PC. Variant functional assessment in Drosophila by overexpression: what can we learn? Genome 2024; 67:158-167. [PMID: 38412472 DOI: 10.1139/gen-2023-0135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
The last decade has been highlighted by the increased use of next-generation DNA sequencing technology to identify novel human disease genes. A critical downstream part of this process is assigning function to a candidate gene variant. Functional studies in Drosophila melanogaster, the common fruit fly, have made a prominent contribution in annotating variant impact in an in vivo system. The use of patient-derived knock-in flies or rescue-based, "humanization", approaches are novel and valuable strategies in variant testing but have been recently widely reviewed. An often-overlooked strategy for determining variant impact has been GAL4/upstream activation sequence-mediated tissue-defined overexpression in Drosophila. This mini-review will summarize the recent contribution of ectopic overexpression of human reference and variant cDNA in Drosophila to assess variant function, interpret the consequence of the variant, and in some cases infer biological mechanisms.
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Affiliation(s)
- Yina Her
- Department of Biochemistry and Medical Genetics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
- Children's Hospital Research Institute of Manitoba (CHRIM), University of Manitoba, Winnipeg, MB, Canada
| | - Danielle M Pascual
- Department of Biochemistry and Medical Genetics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
- Children's Hospital Research Institute of Manitoba (CHRIM), University of Manitoba, Winnipeg, MB, Canada
| | - Zoe Goldstone-Joubert
- Department of Biochemistry and Medical Genetics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
- Children's Hospital Research Institute of Manitoba (CHRIM), University of Manitoba, Winnipeg, MB, Canada
| | - Paul C Marcogliese
- Department of Biochemistry and Medical Genetics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
- Children's Hospital Research Institute of Manitoba (CHRIM), University of Manitoba, Winnipeg, MB, Canada
- Excellence in Neurodevelopment and Rehabilitation Research in Child Health (ENRRICH) Theme, Winnipeg, MB, Canada
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Muñoz-Juan A, Benseny-Cases N, Guha S, Barba I, Caldwell KA, Caldwell GA, Agulló L, Yuste VJ, Laromaine A, Dalfó E. Caenorhabditis elegans RAC1/ced-10 mutants as a new animal model to study very early stages of Parkinson's disease. Prog Neurobiol 2024; 234:102572. [PMID: 38253120 DOI: 10.1016/j.pneurobio.2024.102572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 11/21/2023] [Accepted: 01/15/2024] [Indexed: 01/24/2024]
Abstract
Patients with Parkinson's disease (PD) display non-motor symptoms arising prior to the appearance of motor signs and before a clear diagnosis. Motor and non-motor symptoms correlate with progressive deposition of the protein alpha-synuclein (Asyn) both within and outside of the central nervous system, and its accumulation parallels neurodegeneration. The genome of Caenorhabditis elegans does not encode a homolog of Asyn, thus rendering this nematode an invaluable system with which to investigate PD-related mechanisms in the absence of interference from endogenous Asyn aggregation. CED-10 is the nematode homolog of human RAC1, a small GTPase needed to maintain the function and survival of dopaminergic neurons against human Asyn-induced toxicity in C. elegans. Here, we introduce C. elegans RAC1/ced-10 mutants as a predictive tool to investigate early PD symptoms before neurodegeneration occurs. Deep phenotyping of these animals reveals that, early in development, they displayed altered defecation cycles, GABAergic abnormalities and an increased oxidation index. Moreover, they exhibited altered lipid metabolism evidenced by the accumulation of lipid droplets. Lipidomic fingerprinting indicates that phosphatidylcholine and sphingomyelin, but not phosphatidylethanolamine or phosphatidylserine, were elevated in RAC1/ced-10 mutant nematodes. These collective characteristics reflect the non-motor dysfunction, GABAergic neurotransmission defects, upregulation of stress response mechanisms, and metabolic changes associated with early-onset PD. Thus, we put forward an easy-to-manipulate preclinical animal model to deepen our understanding of early-stage PD and accelerate the translational path for therapeutic target discovery.
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Affiliation(s)
- A Muñoz-Juan
- Group of Nanoparticles and Nanocomposites, Institut Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193 Bellaterra, Barcelona, Spain
| | - N Benseny-Cases
- Biophysics Unit. Department of Biochemistry and Molecular Biology. Universitat Autònoma de Barcelona, Bellaterra 08193, Barcelona, Spain
| | - S Guha
- Nautilus Biotechnology, 835 Industrial Rd, San Carlos, CA 94070, USA
| | - I Barba
- Faculty of Medicine, University of Vic-Central University of Catalonia (UVic-UCC), Institute for Research and Innovation in Life Sciences and Health in Central Catalonia (IRIS-CC), Can Baumann, 08500 Vic, Spain
| | - K A Caldwell
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA; Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, and Nathan Shock Center of Excellence in the Basic Biology of Aging, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, AL 35294, USA
| | - G A Caldwell
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA; Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, and Nathan Shock Center of Excellence in the Basic Biology of Aging, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, AL 35294, USA
| | - L Agulló
- Faculty of Medicine, University of Vic-Central University of Catalonia (UVic-UCC), Institute for Research and Innovation in Life Sciences and Health in Central Catalonia (IRIS-CC), Can Baumann, 08500 Vic, Spain
| | - V J Yuste
- Department of Biochemistry and Molecular Biology, Institut de Neurociències, Faculty of Medicine, M2, Universitat Autònoma de Barcelona (UAB), Bellaterra Campus, Cerdanyola del Vallés, Barcelona, Spain
| | - A Laromaine
- Group of Nanoparticles and Nanocomposites, Institut Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193 Bellaterra, Barcelona, Spain
| | - E Dalfó
- Faculty of Medicine, University of Vic-Central University of Catalonia (UVic-UCC), Institute for Research and Innovation in Life Sciences and Health in Central Catalonia (IRIS-CC), Can Baumann, 08500 Vic, Spain; Department of Biochemistry and Molecular Biology, Institut de Neurociències, Faculty of Medicine, M2, Universitat Autònoma de Barcelona (UAB), Bellaterra Campus, Cerdanyola del Vallés, Barcelona, Spain; Institute of Neurosciences, Faculty of Medicine, Universitat Autònoma de Barcelona (UAB), Campus UAB, 08193 Cerdanyola del Vallès, Spain.
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Gaeta AL, Willicott K, Willicott CW, McKay LE, Keogh CM, Altman TJ, Kimble LC, Yarbrough AL, Caldwell KA, Caldwell GA. Mechanistic impacts of bacterial diet on dopaminergic neurodegeneration in a Caenorhabditis elegans α-synuclein model of Parkinson's disease. iScience 2023; 26:106859. [PMID: 37260751 PMCID: PMC10227375 DOI: 10.1016/j.isci.2023.106859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 04/03/2023] [Accepted: 05/08/2023] [Indexed: 06/02/2023] Open
Abstract
Failure of inherently protective cellular processes and misfolded protein-associated stress contribute to the progressive loss of dopamine (DA) neurons characteristic of Parkinson's disease (PD). A disease-modifying role for the microbiome has recently emerged in PD, representing an impetus to employ the soil-dwelling nematode, Caenorhabditis elegans, as a preclinical model to correlate changes in gene expression with neurodegeneration in transgenic animals grown on distinct bacterial food sources. Even under tightly controlled conditions, hundreds of differentially expressed genes and a robust neuroprotective response were discerned between clonal C. elegans strains overexpressing human alpha-synuclein in the DA neurons fed either one of only two subspecies of Escherichia coli. Moreover, this neuroprotection persisted in a transgenerational manner. Genetic analysis revealed a requirement for the double-stranded RNA (dsRNA)-mediated gene silencing machinery in conferring neuroprotection. In delineating the contribution of individual genes, evidence emerged for endopeptidase activity and heme-associated pathway(s) as mechanistic components for modulating dopaminergic neuroprotection.
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Affiliation(s)
- Anthony L. Gaeta
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Karolina Willicott
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Corey W. Willicott
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Luke E. McKay
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Candice M. Keogh
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Tyler J. Altman
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Logan C. Kimble
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Abigail L. Yarbrough
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Kim A. Caldwell
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
- Center for Convergent Bioscience and Medicine, The University of Alabama, Tuscaloosa, AL 35487, USA
- Alabama Research Institute on Aging, The University of Alabama, Tuscaloosa, AL 35487, USA
- Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, Nathan Shock Center of Excellence for Basic Research in the Biology of Aging, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Guy A. Caldwell
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
- Center for Convergent Bioscience and Medicine, The University of Alabama, Tuscaloosa, AL 35487, USA
- Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, Nathan Shock Center of Excellence for Basic Research in the Biology of Aging, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Starr LA, McKay LE, Peter KN, Seyfarth LM, Berkowitz LA, Caldwell KA, Caldwell GA. Attenuation of Dopaminergic Neurodegeneration in a C. elegans Parkinson's Model through Regulation of Xanthine Dehydrogenase (XDH-1) Expression by the RNA Editase, ADR-2. J Dev Biol 2023; 11:jdb11020020. [PMID: 37218814 DOI: 10.3390/jdb11020020] [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: 03/12/2023] [Revised: 05/16/2023] [Accepted: 05/18/2023] [Indexed: 05/24/2023] Open
Abstract
Differential RNA editing by adenosine deaminases that act on RNA (ADARs) has been implicated in several neurological disorders, including Parkinson's disease (PD). Here, we report results of a RNAi screen of genes differentially regulated in adr-2 mutants, normally encoding the only catalytically active ADAR in Caenorhabditis elegans, ADR-2. Subsequent analysis of candidate genes that alter the misfolding of human α-synuclein (α-syn) and dopaminergic neurodegeneration, two PD pathologies, reveal that reduced expression of xdh-1, the ortholog of human xanthine dehydrogenase (XDH), is protective against α-synuclein-induced dopaminergic neurodegeneration. Further, RNAi experiments show that WHT-2, the worm ortholog of the human ABCG2 transporter and a predicted interactor of XDH-1, is the rate-limiting factor in the ADR-2, XDH-1, WHT-2 system for dopaminergic neuroprotection. In silico structural modeling of WHT-2 indicates that the editing of one nucleotide in the wht-2 mRNA leads to the substitution of threonine with alanine at residue 124 in the WHT-2 protein, changing hydrogen bonds in this region. Thus, we propose a model where wht-2 is edited by ADR-2, which promotes optimal export of uric acid, a known substrate of WHT-2 and a product of XDH-1 activity. In the absence of editing, uric acid export is limited, provoking a reduction in xdh-1 transcription to limit uric acid production and maintain cellular homeostasis. As a result, elevation of uric acid is protective against dopaminergic neuronal cell death. In turn, increased levels of uric acid are associated with a decrease in ROS production. Further, downregulation of xdh-1 is protective against PD pathologies because decreased levels of XDH-1 correlate to a concomitant reduction in xanthine oxidase (XO), the form of the protein whose by-product is superoxide anion. These data indicate that modifying specific targets of RNA editing may represent a promising therapeutic strategy for PD.
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Affiliation(s)
- Lindsey A Starr
- Department of Biological Sciences, Center for Convergent Biomedicine, Alabama Life Research Institute, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Luke E McKay
- Department of Biological Sciences, Center for Convergent Biomedicine, Alabama Life Research Institute, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Kylie N Peter
- Department of Biological Sciences, Center for Convergent Biomedicine, Alabama Life Research Institute, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Lena M Seyfarth
- Department of Biological Sciences, Center for Convergent Biomedicine, Alabama Life Research Institute, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Laura A Berkowitz
- Department of Biological Sciences, Center for Convergent Biomedicine, Alabama Life Research Institute, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Kim A Caldwell
- Department of Biological Sciences, Center for Convergent Biomedicine, Alabama Life Research Institute, The University of Alabama, Tuscaloosa, AL 35487, USA
- Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, Nathan Shock Center of Excellence for the Basic Biology of Aging, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Guy A Caldwell
- Department of Biological Sciences, Center for Convergent Biomedicine, Alabama Life Research Institute, The University of Alabama, Tuscaloosa, AL 35487, USA
- Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, Nathan Shock Center of Excellence for the Basic Biology of Aging, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Thies JL, Willicott K, Craig ML, Greene MR, DuGay CN, Caldwell GA, Caldwell KA. Xanthine Dehydrogenase Is a Modulator of Dopaminergic Neurodegeneration in Response to Bacterial Metabolite Exposure in C. elegans. Cells 2023; 12:cells12081170. [PMID: 37190079 DOI: 10.3390/cells12081170] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 04/03/2023] [Accepted: 04/11/2023] [Indexed: 05/17/2023] Open
Abstract
Oxidative stress is a contributing factor to Parkinson's disease (PD). Considering the prevalence of sporadic PD, environmental exposures are postulated to increase reactive oxygen species and either incite or exacerbate neurodegeneration. We previously determined that exposure to the common soil bacterium, Streptomyces venezuelae (S. ven), enhanced oxidative stress and mitochondrial dysfunction in Caenorhabditis elegans, leading to dopaminergic (DA) neurodegeneration. Here, S. ven metabolite exposure in C. elegans was followed by RNA-Seq analysis. Half of the differentially identified genes (DEGs) were associated with the transcription factor DAF-16 (FOXO), which is a key node in regulating stress response. Our DEGs were enriched for Phase I (CYP) and Phase II (UGT) detoxification genes and non-CYP Phase I enzymes associated with oxidative metabolism, including the downregulated xanthine dehydrogenase gene, xdh-1. The XDH-1 enzyme exhibits reversible interconversion to xanthine oxidase (XO) in response to calcium. S. ven metabolite exposure enhanced XO activity in C. elegans. The chelation of calcium diminishes the conversion of XDH-1 to XO and results in neuroprotection from S. ven exposure, whereas CaCl2 supplementation enhanced neurodegeneration. These results suggest a defense mechanism that delimits the pool of XDH-1 available for interconversion to XO, and associated ROS production, in response to metabolite exposure.
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Affiliation(s)
- Jennifer L Thies
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Karolina Willicott
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Maici L Craig
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Madeline R Greene
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Cassandra N DuGay
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Guy A Caldwell
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Kim A Caldwell
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Integrated regulation of dopaminergic and epigenetic effectors of neuroprotection in Parkinson's disease models. Proc Natl Acad Sci U S A 2023; 120:e2210712120. [PMID: 36745808 PMCID: PMC9963946 DOI: 10.1073/pnas.2210712120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Whole-exome sequencing of Parkinson's disease (PD) patient DNA identified single-nucleotide polymorphisms (SNPs) in the tyrosine nonreceptor kinase-2 (TNK2) gene. Although this kinase had a previously demonstrated activity in preventing the endocytosis of the dopamine reuptake transporter (DAT), a causal role for TNK2-associated dysfunction in PD remains unresolved. We postulated the dopaminergic neurodegeneration resulting from patient-associated variants in TNK2 were a consequence of aberrant or prolonged TNK2 overactivity, the latter being a failure in TNK2 degradation by an E3 ubiquitin ligase, neuronal precursor cell-expressed developmentally down-regulated-4 (NEDD4). Interestingly, systemic RNA interference protein-3 (SID-3) is the sole TNK2 ortholog in the nematode Caenorhabditis elegans, where it is an established effector of epigenetic gene silencing mediated through the dsRNA-transporter, SID-1. We hypothesized that TNK2/SID-3 represents a node of integrated dopaminergic and epigenetic signaling essential to neuronal homeostasis. Use of a TNK2 inhibitor (AIM-100) or a NEDD4 activator [N-aryl benzimidazole 2 (NAB2)] in bioassays for either dopamine- or dsRNA-uptake into worm dopaminergic neurons revealed that sid-3 mutants displayed robust neuroprotection from 6-hydroxydopamine (6-OHDA) exposures, as did AIM-100 or NAB2-treated wild-type animals. Furthermore, NEDD4 activation by NAB2 in rat primary neurons correlated to a reduction in TNK2 levels and the attenuation of 6-OHDA neurotoxicity. CRISPR-edited nematodes engineered to endogenously express SID-3 variants analogous to TNK2 PD-associated SNPs exhibited enhanced susceptibility to dopaminergic neurodegeneration and circumvented the RNAi resistance characteristic of SID-3 dysfunction. This research exemplifies a molecular etiology for PD whereby dopaminergic and epigenetic signaling are coordinately regulated to confer susceptibility or resilience to neurodegeneration.
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