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1.
Methods Mol Biol ; 2814: 209-222, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38954208

RESUMEN

Identifying the mechanisms of action of existing and novel drugs is essential for the development of new compounds for therapeutic and commercial use. Here we provide a technique to identify these mechanisms through isolating mutant cell lines that show resistance to drug-induced phenotypes using Dictyostelium discoideum REMI libraries. This approach provides a robust and rapid chemical-genetic screening technique that enables an unbiased approach to identify proteins and molecular pathways that control drug sensitivity. Mutations that result in drug resistance often occur in target proteins thus identifying the specific protein targets for drugs and bioactive natural products. Following the identification of a list of putative molecular targets user selected compound targets can be analyzed to confirm and validate direct inhibitory effects.


Asunto(s)
Dictyostelium , Mutación , Dictyostelium/genética , Dictyostelium/metabolismo , Enzimas de Restricción del ADN/metabolismo , Biblioteca de Genes , Resistencia a Medicamentos/genética , Bibliotecas de Moléculas Pequeñas/farmacología
2.
Int J Mol Sci ; 25(12)2024 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-38928292

RESUMEN

Tanshinone IIA (T2A) is a bioactive compound that provides promise in the treatment of glioblastoma multiforme (GBM), with a range of molecular mechanisms including the inhibition of the mechanistic target of rapamycin complex 1 (mTORC1) and the induction of autophagy. Recently, T2A has been demonstrated to function through sestrin 2 (SESN) to inhibit mTORC1 activity, but its possible impact on autophagy through this pathway has not been investigated. Here, the model system Dictyostelium discoideum and GBM cell lines were employed to investigate the cellular role of T2A in regulating SESN to inhibit mTORC1 and activate autophagy through a GATOR2 component MIOS. In D. discoideum, T2A treatment induced autophagy and inhibited mTORC1 activity, with both effects lost upon the ablation of SESN (sesn-) or MIOS (mios-). We further investigated the targeting of MIOS to reproduce this effect of T2A, where computational analysis identified 25 novel compounds predicted to strongly bind the human MIOS protein, with one compound (MIOS inhibitor 3; Mi3) reducing cell proliferation in two GBM cells. Furthermore, Mi3 specificity was demonstrated through the loss of potency in the D. discoideum mios- cells regarding cell proliferation and the induction of autophagy. In GBM cells, Mi3 treatment also reduced mTORC1 activity and induced autophagy. Thus, a potential T2A mimetic showing the inhibition of mTORC1 and induction of autophagy in GBM cells was identified.


Asunto(s)
Abietanos , Autofagia , Dictyostelium , Glioblastoma , Diana Mecanicista del Complejo 1 de la Rapamicina , Glioblastoma/tratamiento farmacológico , Glioblastoma/metabolismo , Glioblastoma/patología , Abietanos/farmacología , Humanos , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/antagonistas & inhibidores , Autofagia/efectos de los fármacos , Línea Celular Tumoral , Dictyostelium/efectos de los fármacos , Dictyostelium/metabolismo , Proliferación Celular/efectos de los fármacos , Proteínas Nucleares/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/antagonistas & inhibidores , Sestrinas
3.
Plant Commun ; 5(6): 100846, 2024 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-38460510

RESUMEN

Allelochemicals represent a class of natural products released by plants as root, leaf, and fruit exudates that interfere with the growth and survival of neighboring plants. Understanding how allelochemicals function to regulate plant responses may provide valuable new approaches to better control plant function. One such allelochemical, Myrigalone A (MyA) produced by Myrica gale, inhibits seed germination and seedling growth through an unknown mechanism. Here, we investigate MyA using the tractable model Dictyostelium discoideum and reveal that its activity depends on the conserved homolog of the plant ethylene synthesis protein 1-aminocyclopropane-1-carboxylic acid oxidase (ACO). Furthermore, in silico modeling predicts the direct binding of MyA to ACO within the catalytic pocket. In D. discoideum, ablation of ACO mimics the MyA-dependent developmental delay, which is partially restored by exogenous ethylene, and MyA reduces ethylene production. In Arabidopsis thaliana, MyA treatment delays seed germination, and this effect is rescued by exogenous ethylene. It also mimics the effect of established ACO inhibitors on root and hypocotyl extension, blocks ethylene-dependent root hair production, and reduces ethylene production. Finally, in silico binding analyses identify a range of highly potent ethylene inhibitors that block ethylene-dependent response and reduce ethylene production in Arabidopsis. Thus, we demonstrate a molecular mechanism by which the allelochemical MyA reduces ethylene biosynthesis and identify a range of ultrapotent inhibitors of ethylene-regulated responses.


Asunto(s)
Arabidopsis , Etilenos , Feromonas , Etilenos/biosíntesis , Etilenos/metabolismo , Feromonas/farmacología , Feromonas/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/efectos de los fármacos , Germinación/efectos de los fármacos
4.
Cells ; 12(17)2023 08 28.
Artículo en Inglés | MEDLINE | ID: mdl-37681895

RESUMEN

Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease characterised by progressive degeneration of the motor neurones. An expanded GGGGCC (G4C2) hexanucleotide repeat in C9orf72 is the most common genetic cause of ALS and frontotemporal dementia (FTD); therefore, the resulting disease is known as C9ALS/FTD. Here, we employ a Drosophila melanogaster model of C9ALS/FTD (C9 model) to investigate a role for specific medium-chain fatty acids (MCFAs) in reversing pathogenic outcomes. Drosophila larvae overexpressing the ALS-associated dipeptide repeats (DPRs) in the nervous system exhibit reduced motor function and neuromuscular junction (NMJ) defects. We show that two MCFAs, nonanoic acid (NA) and 4-methyloctanoic acid (4-MOA), can ameliorate impaired motor function in C9 larvae and improve NMJ degeneration, although their mechanisms of action are not identical. NA modified postsynaptic glutamate receptor density, whereas 4-MOA restored defects in the presynaptic vesicular release. We also demonstrate the effects of NA and 4-MOA on metabolism in C9 larvae and implicate various metabolic pathways as dysregulated in our ALS model. Our findings pave the way to identifying novel therapeutic targets and potential treatments for ALS.


Asunto(s)
Esclerosis Amiotrófica Lateral , Demencia Frontotemporal , Enfermedades Neurodegenerativas , Animales , Esclerosis Amiotrófica Lateral/genética , Drosophila , Drosophila melanogaster , Ácidos Grasos , Unión Neuromuscular , Larva
5.
Cell Death Discov ; 9(1): 172, 2023 May 19.
Artículo en Inglés | MEDLINE | ID: mdl-37202382

RESUMEN

Glioblastomas are a highly aggressive cancer type which respond poorly to current pharmaceutical treatments, thus novel therapeutic approaches need to be investigated. One such approach involves the use of the bioactive natural product Tanshinone IIA (T2A) derived from the Chinese herb Danshen, where mechanistic insight for this anti-cancer agent is needed to validate its use. Here, we employ a tractable model system, Dictyostelium discoideum, to provide this insight. T2A potently inhibits cellular proliferation of Dictyostelium, suggesting molecular targets in this model. We show that T2A rapidly reduces phosphoinositide 3 kinase (PI3K) and protein kinase B (PKB) activity, but surprisingly, the downstream complex mechanistic target of rapamycin complex 1 (mTORC1) is only inhibited following chronic treatment. Investigating regulators of mTORC1, including PKB, tuberous sclerosis complex (TSC), and AMP-activated protein kinase (AMPK), suggests these enzymes were not responsible for this effect, implicating an additional molecular mechanism of T2A. We identify this mechanism as the increased expression of sestrin, a negative regulator of mTORC1. We further show that combinatory treatment using a PI3K inhibitor and T2A gives rise to a synergistic inhibition of cell proliferation. We then translate our findings to human and mouse-derived glioblastoma cell lines, where both a PI3K inhibitor (Paxalisib) and T2A reduces glioblastoma proliferation in monolayer cultures and in spheroid expansion, with combinatory treatment significantly enhancing this effect. Thus, we propose a new approach for cancer treatment, including glioblastomas, through combinatory treatment with PI3K inhibitors and T2A.

6.
Ann Clin Transl Neurol ; 10(5): 787-801, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-37000947

RESUMEN

OBJECTIVE: The goal of this study is to demonstrate the utility of a growth assay to quantify the functional impact of single nucleotide variants (SNVs) in SLC2A1, the gene responsible for Glut1DS. METHODS: The functional impact of 40 SNVs in SLC2A1 was quantitatively determined in HAP1 cells in which SLC2A1 is required for growth. Donor libraries were introduced into the endogenous SLC2A1 gene in HAP1-Lig4KO cells using CRISPR/Cas9. Cell populations were harvested and sequenced to quantify the effect of variants on growth and generate a functional score. Quantitative functional scores were compared to 3-OMG uptake, SLC2A1 cell surface expression, CADD score, and clinical data, including CSF/blood glucose ratio. RESULTS: Nonsense variants (N = 3) were reduced in cell culture over time resulting in negative scores (mean score: -1.15 ± 0.17), whereas synonymous variants (N = 10) were not depleted (mean score: 0.25 ± 0.12) (P < 2e-16). Missense variants (N = 27) yielded a range of functional scores including slightly negative scores, supporting a partial function and intermediate phenotype. Several variants with normal results on either cell surface expression (p.N34S and p.W65R) or 3-OMG uptake (p.W65R) had negative functional scores. There is a moderate but significant correlation between our functional scores and CADD scores. INTERPRETATION: Cell growth is useful to quantitatively determine the functional effects of SLC2A1 variants. Nonsense variants were reliably distinguished from benign variants in this in vitro functional assay. For facilitating early diagnosis and therapeutic intervention, future work is needed to determine the functional effect of every possible variant in SLC2A1.


Asunto(s)
Errores Innatos del Metabolismo de los Carbohidratos , Humanos , Fenotipo , Errores Innatos del Metabolismo de los Carbohidratos/genética , Errores Innatos del Metabolismo de los Carbohidratos/diagnóstico , Proteínas de Transporte de Monosacáridos/genética , Mutación Missense , Transportador de Glucosa de Tipo 1/genética
7.
Artículo en Inglés | MEDLINE | ID: mdl-36568268

RESUMEN

The rationale for using thalidomide (THD) as a treatment for nausea and vomiting during pregnancy in the late 1950s appears to have been based on its sedative or hypnotic properties. In contrast to contemporaneous studies on the anti-emetic activity of phenothiazines, we were unable to identify publications reporting preclinical or clinical evaluation of THD as an anti-emetic. Our survey of the literature revealed a clinical study in 1965 showing THD reduced vomiting in cancer chemotherapy which was substantiated by similar studies from 2000, particularly showing efficacy in the delayed phase of chemotherapy-induced nausea and vomiting. To identify the mechanism(s) potentially involved in thalidomide's anti-emetic activity we reviewed its pharmacology in the light of nausea and vomiting mechanisms and their pharmacology with a particular emphasis on chemotherapy and pregnancy. The process identified the following potential mechanisms: reduced secretion of Growth Differentiation Factor 15, suppression of inflammation/prostaglandin production, downregulation of cytotoxic drug induced upregulation of iNOS, and modulation of BK (KCa1.1) channels and GABAA/glutamate transmission at critical points in the emetic pathways (nucleus tractus solitarius, area postrema). We propose ways to investigate these hypothesized mechanisms and discuss the associated challenges (e.g., objective quantification of nausea) in addition to some of the more general aspects of developing novel drugs to treat nausea and vomiting.

8.
Br J Pharmacol ; 179(14): 3628-3644, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-32959886

RESUMEN

BACKGROUND AND PURPOSE: AMPA receptors, which shape excitatory postsynaptic currents and are directly involved in overactivation of synaptic function during seizures, represent a well-accepted target for anti-epileptic drugs. Trans-4-butylcyclohexane carboxylic acid (4-BCCA) has emerged as a new promising anti-epileptic drug in several in vitro and in vivo seizure models, but the mechanism of its action remained unknown. The purpose of this study is to characterize structure and dynamics of 4-BCCA interaction with AMPA receptors. EXPERIMENTAL APPROACH: We studied the molecular mechanism of AMPA receptor inhibition by 4-BCCA using a combination of X-ray crystallography, mutagenesis, electrophysiological assays, and molecular dynamics simulations. KEY RESULTS: We identified 4-BCCA binding sites in the transmembrane domain (TMD) of AMPA receptor, at the lateral portals formed by transmembrane segments M1-M4. At this binding site, 4-BCCA is very dynamic, assumes multiple poses, and can enter the ion channel pore. CONCLUSION AND IMPLICATIONS: 4-BCCA represents a low-affinity inhibitor of AMPA receptors that acts at the TMD sites distinct from non-competitive inhibitors, such as the anti-epileptic drug perampanel and the ion channel blockers. Further studies might examine the possibsility of synergistic use of these inhibitors in treatment of epilepsy and a wide range of neurological disorders and gliomas. LINKED ARTICLES: This article is part of a themed issue on Structure Guided Pharmacology of Membrane Proteins (BJP 75th Anniversary). To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v179.14/issuetoc.


Asunto(s)
Ácidos Carboxílicos , Receptores AMPA , Ciclohexanos , Humanos , Receptores AMPA/metabolismo , Convulsiones
9.
Brain Commun ; 3(4): fcab160, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34729477

RESUMEN

This prospective open-label feasibility study aimed to evaluate acceptability, tolerability and compliance with dietary intervention with K.Vita, a medical food containing a unique ratio of decanoic acid to octanoic acid, in individuals with drug-resistant epilepsy. Adults and children aged 3-18 years with drug-resistant epilepsy took K.Vita daily whilst limiting high-refined sugar food and beverages. K.Vita was introduced incrementally with the aim of achieving ≤35% energy requirements for children or 240 ml for adults. Primary outcome measures were assessed by study completion, participant diary, acceptability questionnaire and K.Vita intake. Reduction in seizures or paroxysmal events was a secondary outcome. 23/35 (66%) children and 18/26 (69%) adults completed the study; completion rates were higher when K.Vita was introduced more gradually. Gastrointestinal disturbances were the primary reason for discontinuation, but symptoms were similar to those reported from ketogenic diets and incidence decreased over time. At least three-quarters of participants/caregivers reported favourably on sensory attributes of K.Vita, such as taste, texture and appearance, and ease of use. Adults achieved a median intake of 240 ml K.Vita, and children 120 ml (19% daily energy). Three children and one adult had ß-hydroxybutyrate >1 mmol/l. There was 50% (95% CI 39-61%) reduction in mean frequency of seizures/events. Reduction in seizures or paroxysmal events correlated significantly with blood concentrations of medium chain fatty acids (C10 and C8) but not ß-hydroxybutyrate. K.Vita was well accepted and tolerated. Side effects were mild and resolved with dietetic support. Individuals who completed the study complied with K.Vita and additional dietary modifications. Dietary intervention had a beneficial effect on frequency of seizures or paroxysmal events, despite absent or very low levels of ketosis. We suggest that K.Vita may be valuable to those with drug-resistant epilepsy, particularly those who cannot tolerate or do not have access to ketogenic diets, and may allow for more liberal dietary intake compared to ketogenic diets, with mechanisms of action perhaps unrelated to ketosis. Further studies of effectiveness of K.Vita are warranted.

10.
Cells ; 10(11)2021 10 29.
Artículo en Inglés | MEDLINE | ID: mdl-34831171

RESUMEN

Ketogenic diets, used in epilepsy treatment, are considered to work through reduced glucose and ketone generation to regulate a range of cellular process including autophagy induction. Recent studies into the medium-chain triglyceride (MCT) ketogenic diet have suggested that medium-chain fatty acids (MCFAs) provided in the diet, decanoic acid and octanoic acid, cause specific therapeutic effects independent of glucose reduction, although a role in autophagy has not been investigated. Both autophagy and MCFAs have been widely studied in Dictyostelium, with findings providing important advances in the study of autophagy-related pathologies such as neurodegenerative diseases. Here, we utilize this model to analyze a role for MCFAs in regulating autophagy. We show that treatment with decanoic acid but not octanoic acid induces autophagosome formation and modulates autophagic flux in high glucose conditions. To investigate this effect, decanoic acid, but not octanoic acid, was found to induce the expression of autophagy-inducing proteins (Atg1 and Atg8), providing a mechanism for this effect. Finally, we demonstrate a range of related fatty acid derivatives with seizure control activity, 4BCCA, 4EOA, and Epilim (valproic acid), also function to induce autophagosome formation in this model. Thus, our data suggest that decanoic acid and related compounds may provide a less-restrictive therapeutic approach to activate autophagy.


Asunto(s)
Autofagia , Ácidos Decanoicos/farmacología , Dictyostelium/citología , Autofagosomas/efectos de los fármacos , Autofagosomas/metabolismo , Autofagia/efectos de los fármacos , Dictyostelium/efectos de los fármacos , Dictyostelium/metabolismo , Fosfatos de Fosfatidilinositol/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo
11.
Cells ; 10(11)2021 11 05.
Artículo en Inglés | MEDLINE | ID: mdl-34831258

RESUMEN

The social amoeba Dictyostelium discoideum provides an excellent model for research across a broad range of disciplines within biology. The organism diverged from the plant, yeast, fungi and animal kingdoms around 1 billion years ago but retains common aspects found in these kingdoms. Dictyostelium has a low level of genetic complexity and provides a range of molecular, cellular, biochemical and developmental biology experimental techniques, enabling multidisciplinary studies to be carried out in a wide range of areas, leading to research breakthroughs. Numerous laboratories within the United Kingdom employ Dictyostelium as their core research model. This review introduces Dictyostelium and then highlights research from several leading British research laboratories, covering their distinct areas of research, the benefits of using the model, and the breakthroughs that have arisen due to the use of Dictyostelium as a tractable model system.


Asunto(s)
Biología , Dictyostelium/fisiología , Modelos Biológicos , Investigación , Animales , Dictyostelium/citología , Descubrimiento de Drogas , Procesamiento Proteico-Postraduccional , Reino Unido
12.
Front Cell Dev Biol ; 9: 722066, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34589488

RESUMEN

Ketogenic diets have been utilized for many years to improve health, and as a dietary approach for the treatment of a range of diseases, where the mechanism of these low carbohydrate and high fat diets is widely considered to be through the production of metabolic products of fat breakdown, called ketones. One of these diets, the medium chain triglyceride ketogenic diet, involves high fat dietary intake in the form of medium chain fatty acids (MCFAs), decanoic and octanoic acid, and is commonly used in endurance and high intensity exercises but has also demonstrated beneficial effects in the treatment of numerous pathologies including drug resistant epilepsy, cancer, and diabetes. Recent advances, using Dictyostelium discoideum as a model, have controversially proposed several direct molecular mechanisms for decanoic acid in this diet, independent of ketone generation. Studies in this model have identified that decanoic acid reduces phosphoinositide turnover, diacylglycerol kinase (DGK) activity, and also inhibits the mechanistic target of rapamycin complex 1 (mTORC1). These discoveries could potentially impact the treatment of a range of disorders including epilepsy, cancer and bipolar disorder. In this review, we summarize the newly proposed mechanisms for decanoic acid, identified using D. discoideum, and highlight potential roles in health and disease treatment.

13.
Br J Pharmacol ; 178(5): 1149-1163, 2021 03.
Artículo en Inglés | MEDLINE | ID: mdl-33347604

RESUMEN

BACKGROUND AND PURPOSE: Cannabidiol (CBD) has been shown to differentially regulate the mechanistic target of rapamycin complex 1 (mTORC1) in preclinical models of disease, where it reduces activity in models of epilepsies and cancer and increases it in models of multiple sclerosis (MS) and psychosis. Here, we investigate the effects of phytocannabinoids on mTORC1 and define a molecular mechanism. EXPERIMENTAL APPROACH: A novel mechanism for phytocannabinoids was identified using the tractable model system, Dictyostelium discoideum. Using mouse embryonic fibroblasts, we further validate this new mechanism of action. We demonstrate clinical relevance using cells derived from healthy individuals and from people with MS (pwMS). KEY RESULTS: Both CBD and the more abundant cannabigerol (CBG) enhance mTORC1 activity in D. discoideum. We identify a mechanism for this effect involving inositol polyphosphate multikinase (IPMK), where elevated IPMK expression reverses the response to phytocannabinoids, decreasing mTORC1 activity upon treatment, providing new insight on phytocannabinoids' actions. We further validated this mechanism using mouse embryonic fibroblasts. Clinical relevance of this effect was shown in primary human peripheral blood mononuclear cells, where CBD and CBG treatment increased mTORC1 activity in cells derived from healthy individuals and decreased mTORC1 activity in cells derived from pwMS. CONCLUSION AND IMPLICATIONS: Our findings suggest that both CBD and the abundant CBG differentially regulate mTORC1 signalling through a mechanism dependent on the activity of the upstream IPMK signalling pathway, with potential relevance to the treatment of mTOR-related disorders, including MS.


Asunto(s)
Cannabinoides/farmacología , Diana Mecanicista del Complejo 1 de la Rapamicina , Fosfotransferasas (Aceptor de Grupo Alcohol) , Animales , Células Cultivadas , Fibroblastos , Leucocitos Mononucleares , Ratones
14.
Proc Natl Acad Sci U S A ; 117(38): 23617-23625, 2020 09 22.
Artículo en Inglés | MEDLINE | ID: mdl-32879008

RESUMEN

Low-glucose and -insulin conditions, associated with ketogenic diets, can reduce the activity of the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway, potentially leading to a range of positive medical and health-related effects. Here, we determined whether mTORC1 signaling is also a target for decanoic acid, a key component of the medium-chain triglyceride (MCT) ketogenic diet. Using a tractable model system, Dictyostelium, we show that decanoic acid can decrease mTORC1 activity, under conditions of constant glucose and in the absence of insulin, measured by phosphorylation of eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1). We determine that this effect of decanoic acid is dependent on a ubiquitin regulatory X domain-containing protein, mediating inhibition of a conserved Dictyostelium AAA ATPase, p97, a homolog of the human transitional endoplasmic reticulum ATPase (VCP/p97) protein. We then demonstrate that decanoic acid decreases mTORC1 activity in the absence of insulin and under high-glucose conditions in ex vivo rat hippocampus and in tuberous sclerosis complex (TSC) patient-derived astrocytes. Our data therefore indicate that dietary decanoic acid may provide a new therapeutic approach to down-regulate mTORC1 signaling.


Asunto(s)
Ácidos Decanoicos/farmacología , Diana Mecanicista del Complejo 1 de la Rapamicina , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Animales , Astrocitos/metabolismo , Proteínas de Ciclo Celular/metabolismo , Células Cultivadas , Dictyostelium/efectos de los fármacos , Dictyostelium/crecimiento & desarrollo , Dictyostelium/metabolismo , Epilepsia , Glucosa/metabolismo , Hipocampo/química , Hipocampo/metabolismo , Humanos , Insulina/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/antagonistas & inhibidores , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/farmacología , Factores de Iniciación de Péptidos , Fosforilación , Ratas
15.
Biochem Biophys Rep ; 22: 100751, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32258439

RESUMEN

Visualizing mitochondria in living Dictyostelium discoideum cells using fluorescent dyes is often problematic due to variability in staining, metabolism of the dyes, and unknown potential effects of the dyes on mitochondrial function. We show that fluorescent labelling of mitochondria, using an N-terminal mitochondrial localization sequence derived from the D. discoideum protein GcvH1 (glycine cleavage system H1) attached to a red fluorescent protein enables clear mitochondrial imaging. We also show that this labelling has no effect upon mitochondria load or respiratory function.

16.
Br J Pharmacol ; 177(4): 912-928, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-31693171

RESUMEN

BACKGROUND AND PURPOSE: Epidiolex™, a form of highly purified cannabidiol (CBD) derived from Cannabis plants, has demonstrated seizure control activity in patients with Dravet syndrome, without a fully elucidated mechanism of action. We have employed an unbiased approach to investigate this mechanism at a cellular level. EXPERIMENTAL APPROACH: We use a tractable biomedical model organism, Dictyostelium, to identify a protein controlling the effect of CBD and characterize this mechanism. We then translate these results to a Dravet syndrome mouse model and an acute in vitro seizure model. KEY RESULTS: CBD activity is partially dependent upon the mitochondrial glycine cleavage system component, GcvH1 in Dictyostelium, orthologous to the human glycine cleavage system component H protein, which is functionally linked to folate one-carbon metabolism (FOCM). Analysis of FOCM components identified a mechanism for CBD in directly inhibiting methionine synthesis. Analysis of brain tissue from a Dravet syndrome mouse model also showed drastically altered levels of one-carbon components including methionine, and an in vitro rat seizure model showed an elevated level of methionine that is attenuated following CBD treatment. CONCLUSIONS AND IMPLICATIONS: Our results suggest a novel mechanism for CBD in the regulating methionine levels and identify altered one-carbon metabolism in Dravet syndrome and seizure activity.


Asunto(s)
Cannabidiol , Dictyostelium , Epilepsia , Síndrome de Lennox-Gastaut , Animales , Anticonvulsivantes/uso terapéutico , Cannabidiol/uso terapéutico , Ciclo del Carbono , Epilepsia/tratamiento farmacológico , Humanos , Síndrome de Lennox-Gastaut/tratamiento farmacológico , Metionina/uso terapéutico , Ratas
17.
Int J Dev Biol ; 63(8-9-10): 541-550, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31840791

RESUMEN

Developing novel compounds for the treatment of diseases remains one of the highest priorities in biomedical research, where it is critical to identify their targets and how they work at a cellular level. Most studies in this area employ mammalian models, since rodents or non-human primates are seen as a good approximation for humans. However, using mammalian models can be problematic for a range of reasons, including high genetic redundancy and the essential role for many proteins in development. More importantly, it is very difficult to identify how compounds function at a cellular or molecular level in these models without a previously suggested mechanism or target. So how can we identify targets of medicinal compounds? In this review we outline the use of an innovative and tractable model system, Dictyostelium discoideum, to provide useful insight to the cellular and molecular functions of both therapeutic drugs and pharmacologically active natural products. We outline the advantages of using this model, and then provide a range of exemplar studies using D. discoideum in pharmacological research to demonstrate breakthroughs in understanding the action and effects of compounds, and the subsequent translational of these advances to mammalian models leading to potential improvements in societal health.


Asunto(s)
Productos Biológicos/farmacología , Dictyostelium/fisiología , Descubrimiento de Drogas , Animales , Antiinfecciosos/farmacología , Infecciones Bacterianas/tratamiento farmacológico , Trastorno Bipolar/tratamiento farmacológico , Cafeína/farmacología , Dictyostelium/genética , Epilepsia/tratamiento farmacológico , Flavonoides/farmacología , Humanos , Modelos Animales , Modelos Biológicos , Neoplasias/tratamiento farmacológico
19.
Autophagy ; 15(8): 1407-1418, 2019 08.
Artículo en Inglés | MEDLINE | ID: mdl-30806144

RESUMEN

Mutations in the γ-secretase complex are strongly associated with familial Alzheimer disease. Both proteolytic and non-proteolytic functions for the γ-secretase complex have been previously described in mammalian model organisms, but their relative contributions to disease pathology remain unclear. Here, we dissect the roles of orthologs of the γ-secretase components in the model system Dictyostelium, focusing on endocytosis, lysosomal activity and autophagy. In this model, we show that the orthologs of PSEN (psenA and psenB), Ncstn (nicastrin) and Aph-1 (gamma-secretase subunit Aph-1), are necessary for optimal fluid-phase uptake by macropinocytosis and in multicellular development under basic pH conditions. Disruption of either psenA/B or Aph-1 proteins also leads to disrupted phagosomal proteolysis as well as decreased autophagosomal acidification and autophagic flux. This indicates a general defect in lysosomal trafficking and degradation, which we show leads to the accumulation of ubiquitinated protein aggregates in cells lacking psenA/B and Aph-1 proteins. Importantly, we find that all the endocytic defects observed in Dictyostelium PSEN ortholog mutants can be fully rescued by proteolytically inactive Dictyostelium psenB and human PSEN1 proteins. Our data therefore demonstrates an evolutionarily conserved non-proteolytic role for presenilin, and γ-secretase component orthologs, in maintaining Dictyostelium lysosomal trafficking and autophagy. Abbreviations: Atg8: autophagy protein 8a; Aph-1: gamma-secretase subunit Aph-1; crtA: calreticulin; ER: endoplasmic reticulum; GFP: green fluorescent protein; GSK3B: glycogen synthase kinase 3 beta; Ncstn: nicastrin; PSEN1: presenilin 1; psenA and psenB: Dictyostelium presenilin A and B; TRITC; tetramethylrhodamine isothiocyanate.


Asunto(s)
Secretasas de la Proteína Precursora del Amiloide/metabolismo , Autofagia , Dictyostelium/metabolismo , Lisosomas/metabolismo , Presenilinas/metabolismo , Proteolisis , Homología de Secuencia de Aminoácido , Endocitosis , Proteínas Fluorescentes Verdes/metabolismo , Concentración de Iones de Hidrógeno , Mutación/genética , Ubiquitina/metabolismo , Ubiquitinación
20.
Epilepsia ; 59(11): e172-e178, 2018 11.
Artículo en Inglés | MEDLINE | ID: mdl-30324610

RESUMEN

Perampanel is an adjunctive treatment for epilepsy that works through the direct inhibition of AMPA receptors. The same molecular mechanism has recently been shown for a fatty acid, decanoic acid, prescribed in the medium chain triglyceride ketogenic diet for the treatment of patients with drug-resistant epilepsy. Because each compound has been proposed to act through a distinct AMPA receptor binding site, we predicted that perampanel and decanoic acid would act synergistically against AMPA receptors and, consequently, seizures. Here, we show a synergistic interaction between perampanel and decanoic acid in direct AMPA receptor inhibition, in an ex vivo model of seizure activity, and against seizure-induced activity in human brain slices. These data support a potential role for combination treatment using perampanel and dietary decanoic acid to provide enhanced seizure control.


Asunto(s)
Anticonvulsivantes/farmacología , Encéfalo/efectos de los fármacos , Ácidos Decanoicos/farmacología , Piridonas/farmacología , Receptores AMPA/metabolismo , Animales , Dopamina/farmacología , Relación Dosis-Respuesta a Droga , Sinergismo Farmacológico , Potenciales Evocados/efectos de los fármacos , Hipocampo/efectos de los fármacos , Humanos , Técnicas In Vitro , Nitrilos , Oocitos , Pentilenotetrazol/toxicidad , Ratas , Xenopus
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