RESUMO
Aspartate-glutamate carrier isoform 1 (AGC1) is a carrier responsible for the export of mitochondrial aspartate in exchange for cytosolic glutamate and is part of the malate-aspartate shuttle, essential for the balance of reducing equivalents in the cells. In the brain, mutations in SLC25A12 gene, encoding for AGC1, cause an ultra-rare genetic disease, reported as a neurodevelopmental encephalopathy, whose symptoms include global hypomyelination, arrested psychomotor development, hypotonia and seizures. Among the biological components most affected by AGC1 deficiency are oligodendrocytes, glial cells responsible for myelination processes, and their precursors [oligodendrocyte progenitor cells (OPCs)]. The AGC1 silencing in an in vitro model of OPCs was documented to cause defects of proliferation and differentiation, mediated by alterations of histone acetylation/deacetylation. Disrupting AGC1 activity could possibly reduce the availability of acetyl groups, leading to perturbation of many biological pathways, such as histone modifications and fatty acids formation for myelin production. Here, we explore the transcriptome of mouse OPCs partially silenced for AGC1, reporting results of canonical analyses (differential expression) and pathway enrichment analyses, which highlight a disruption in fatty acids synthesis from both a regulatory and enzymatic stand. We further investigate the cellular effects of AGC1 deficiency through the identification of most affected transcriptional networks and altered alternative splicing. Transcriptional data were integrated with differential metabolite abundance analysis, showing downregulation of several amino acids, including glutamine and aspartate. Taken together, our results provide a molecular foundation for the effects of AGC1 deficiency in OPCs, highlighting the molecular mechanisms affected and providing a list of actionable targets to mitigate the effects of this pathology.
Assuntos
Sistemas de Transporte de Aminoácidos Acídicos/deficiência , Antiporters/deficiência , Doenças Desmielinizantes Hereditárias do Sistema Nervoso Central , Doenças Mitocondriais , Células Precursoras de Oligodendrócitos , Transtornos Psicomotores , Camundongos , Animais , Regulação para Baixo/genética , Células Precursoras de Oligodendrócitos/metabolismo , Ácido Aspártico/metabolismo , Isoformas de Proteínas/metabolismo , Ácidos GraxosRESUMO
The accurate characterisation of metabolic profiles is an important prerequisite to determine the rate and the efficiency of the metabolic pathways taking place in the cells. Changes in the balance of metabolites involved in vital processes such as glycolysis, tricarboxylic acid (TCA) cycle, oxidative phosphorylation (OXPHOS), as well as in the biochemical pathways related to amino acids, lipids, nucleotides, and their precursors reflect the physiological condition of the cells and may contribute to the development of various human diseases. The feasible and reliable measurement of a wide array of metabolites and biomarkers possesses great potential to elucidate physiological and pathological mechanisms, aid preclinical drug development and highlight potential therapeutic targets. An effective, straightforward, sensitive, and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) approach was developed for the simultaneous quali-quantitative analysis of 41 compounds in both cell pellet and cell growth medium obtained from brain-derived cell cultures. Sample pretreatment miniaturisation was achieved thanks to the development and optimisation of an original extraction/purification approach based on digitally programmed microextraction by packed sorbent (eVol®-MEPS). MEPS allows satisfactory and reproducible clean-up and preconcentration of both low-volume homogenate cell pellet lysate and cell growth medium with advantages including, but not limited to, minimal sample handling and method sustainability in terms of sample, solvents, and energy consumption. The MEPS-LC-MS/MS method showed good sensitivity, selectivity, linearity, and precision. As a proof of concept, the developed method was successfully applied to the analysis of both cell pellet and cell growth medium obtained from a line of mouse immortalised oligodendrocyte precursor cells (OPCs; Oli-neu cell line), leading to the unambiguous determination of all the considered target analytes. This method is thus expected to be suitable for targeted, quantitative metabolic profiling in most brain cell models, thus allowing accurate investigations on the biochemical pathways that can be altered in central nervous system (CNS) neuropathologies, including e.g., mitochondrial respiration and glycolysis, or use of specific nutrients for growth and proliferation, or lipid, amino acid and nucleotide metabolism.
Assuntos
Microextração em Fase Sólida , Espectrometria de Massas em Tandem , Humanos , Camundongos , Animais , Cromatografia Líquida/métodos , Espectrometria de Massas em Tandem/métodos , Microextração em Fase Sólida/métodos , Encéfalo , Técnicas de Cultura de CélulasRESUMO
Smith-Magenis syndrome (SMS) is a neurodevelopmental disorder characterized by cognitive and behavioral symptoms, obesity, and sleep disturbance, and no therapy has been developed to alleviate its symptoms or delay disease onset. SMS occurs due to haploinsufficiency of the retinoic acid-induced-1 (RAI1) gene caused by either chromosomal deletion (SMS-del) or RAI1 missense/nonsense mutation. The molecular mechanisms underlying SMS are unknown. Here, we generated and characterized primary cells derived from four SMS patients (two with SMS-del and two carrying RAI1 point mutations) and four control subjects to investigate the pathogenetic processes underlying SMS. By combining transcriptomic and lipidomic analyses, we found altered expression of lipid and lysosomal genes, deregulation of lipid metabolism, accumulation of lipid droplets, and blocked autophagic flux. We also found that SMS cells exhibited increased cell death associated with the mitochondrial pathology and the production of reactive oxygen species. Treatment with N-acetylcysteine reduced cell death and lipid accumulation, which suggests a causative link between metabolic dyshomeostasis and cell viability. Our results highlight the pathological processes in human SMS cells involving lipid metabolism, autophagy defects and mitochondrial dysfunction and suggest new potential therapeutic targets for patient treatment.
Assuntos
Síndrome de Smith-Magenis , Humanos , Síndrome de Smith-Magenis/diagnóstico , Síndrome de Smith-Magenis/genética , Síndrome de Smith-Magenis/patologia , Haploinsuficiência/genética , Metabolismo dos Lipídeos/genética , Fatores de Transcrição/metabolismo , Transativadores/metabolismo , Fenótipo , Autofagia/genética , Tretinoína/farmacologia , Tretinoína/metabolismo , LipídeosRESUMO
BACKGROUND: Bisphenol A (BPA) and perfluorooctanoic acid (PFOA) are synthetic compounds widely utilized in industrial activities devoted to the production of daily life plastic, metal products, and packaging from which they are able to migrate to food and water. Due to their persistence in the environment, living organisms are chronically exposed to these pollutants. BPA and PFOA have adverse effects on tissues and organs. The aim of this study was to identify the molecular targets and biochemical mechanisms involved in their toxicity. METHODS: HepG2 and HaCaT cells were treated with BPA or PFOA, and the trypan blue exclusion test and 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay were performed to define the conditions for subsequent investigations. We conducted quantitative PCR and western blot analysis to evaluate the expression of proteins involved in nitric oxide (NO) signaling. Cell-based assays were carried out to evaluate reactive oxygen species (ROS) production, nitrite/nitrate (NOx) accumulation, 3-nitrotyrosine (3-NT) formation, and mitochondrial membrane potential (MMP) determination in treated cells. RESULTS: HepG2 and HaCaT cells incubated for 24 h with subtoxic concentrations of BPA or PFOA (50 and 10 µM, respectively) exhibited altered mRNA and protein expression levels of NO synthase isoforms, manganese superoxide dismutase, and cytochrome c. Treatment with PFOA led to activation of inducible NO synthase (NOS), a marker of nitrosative stress, accompanied by the increased production of ROS, NOx, and 3-NT and alterations of the MMP compared to controls. CONCLUSIONS: The results of this study indicate the major involvement of the NO signaling axis in the persistent alteration of cell redox homeostasis and mitochondrial dysfunction induced by BPA and PFOA, highlighting the specific role of PFOA in NOS regulation and induction of nitro-oxidative stress.
Assuntos
Mitocôndrias , Estresse Oxidativo , Humanos , Espécies Reativas de Oxigênio/metabolismo , Linhagem Celular , Mitocôndrias/metabolismoRESUMO
Mitochondrial aspartate-glutamate carrier isoform 1 (AGC1) deficiency is an ultra-rare genetic disease characterized by global hypomyelination and brain atrophy, caused by mutations in the SLC25A12 gene leading to a reduction in AGC1 activity. In both neuronal precursor cells and oligodendrocytes precursor cells (NPCs and OPCs), the AGC1 determines reduced proliferation with an accelerated differentiation of OPCs, both associated with gene expression dysregulation. Epigenetic regulation of gene expression through histone acetylation plays a crucial role in the proliferation/differentiation of both NPCs and OPCs and is modulated by mitochondrial metabolism. In AGC1 deficiency models, both OPCs and NPCs show an altered expression of transcription factors involved in the proliferation/differentiation of brain precursor cells (BPCs) as well as a reduction in histone acetylation with a parallel alteration in the expression and activity of histone acetyltransferases (HATs) and histone deacetylases (HDACs). In this study, histone acetylation dysfunctions have been dissected in in vitro models of AGC1 deficiency OPCs (Oli-Neu cells) and NPCs (neurospheres), in physiological conditions and following pharmacological treatments. The inhibition of HATs by curcumin arrests the proliferation of OPCs leading to their differentiation, while the inhibition of HDACs by suberanilohydroxamic acid (SAHA) has only a limited effect on proliferation, but it significantly stimulates the differentiation of OPCs. In NPCs, both treatments determine an alteration in the commitment toward glial cells. These data contribute to clarifying the molecular and epigenetic mechanisms regulating the proliferation/differentiation of OPCs and NPCs. This will help to identify potential targets for new therapeutic approaches that are able to increase the OPCs pool and to sustain their differentiation toward oligodendrocytes and to myelination/remyelination processes in AGC1 deficiency, as well as in other white matter neuropathologies.
RESUMO
Gab2 is a scaffolding protein, overexpressed in many types of cancers, that plays a key role in the formation of signaling complexes involved in cellular proliferation, migration, and differentiation. The interaction between Gab2 and the C-terminal SH3 domain of the protein Grb2 is crucial for the activation of the proliferation-signaling pathway Ras/Erk, thus representing a potential pharmacological target. In this study, we identified, by virtual screening, seven potential inhibitor molecules that were experimentally tested through kinetic and equilibrium binding experiments. One compound showed a remarkable effect in lowering the affinity of the C-SH3 domain for Gab2. This inhibitory effect was subsequently validated in cellula by using lung cancer cell lines A549 and H1299. Our results are discussed under the light of previous works on the C-SH3:Gab2 interaction.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/química , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteína Adaptadora GRB2/química , Proteína Adaptadora GRB2/metabolismo , Domínios de Homologia de src , Linhagem Celular Tumoral , Fluorescência , Humanos , Cinética , Modelos Moleculares , Ligação Proteica , Reprodutibilidade dos TestesRESUMO
Nutrient utilization and reshaping of metabolism in cancer cells is a well-known driver of malignant transformation. Less clear is the influence of the local microenvironment on metastasis formation and choice of the final organ to invade. Here we show that the level of the amino acid serine in the cytosol affects the migratory properties of lung adenocarcinoma (LUAD) cells. Inhibition of serine or glycine uptake from the extracellular milieu, as well as knockdown of the cytosolic one-carbon metabolism enzyme serine hydroxymethyltransferase (SHMT1), abolishes migration. Using rescue experiments with a brain extracellular extract, and direct measurements, we demonstrate that cytosolic serine starvation controls cell movement by increasing reactive oxygen species formation and decreasing ATP levels, thereby promoting activation of the AMP sensor kinase (AMPK) by phosphorylation. Activation of AMPK induces remodeling of the cytoskeleton and finally controls cell motility. These results highlight that cytosolic serine metabolism plays a key role in controlling motility, suggesting that cells are able to dynamically exploit the compartmentalization of this metabolism to adapt their metabolic needs to different cell functions (movement vs. proliferation). We propose a model to explain the relevance of serine/glycine metabolism in the preferential colonization of the brain by LUAD cells and suggest that the inhibition of serine/glycine uptake and/or cytosolic SHMT1 might represent a successful strategy to limit the formation of brain metastasis from primary tumors, a major cause of death in these patients.
Assuntos
Adenocarcinoma de Pulmão/genética , Adenilato Quinase/metabolismo , Glicina Hidroximetiltransferase/metabolismo , Adenocarcinoma de Pulmão/patologia , Movimento Celular , HumanosRESUMO
BACKGROUND/AIM: The connection between prostate cancer and inflammation has been proposed many years ago, but very little is known about the metabolic adaptations of prostate cells in case of infection or inflammation. The aim of this study was to examine the effect of the stimulation of Toll-like receptor 3 (TLR3) on the metabolism of prostate cancer (PCa) cell lines and benign prostate cells. MATERIALS AND METHODS: Cytofluorimetry, qRT-PCR, western blot and Gas-chromatography/Mass-spectrometry were used. RESULTS: Reprogramming of glucose utilization involving hypoxia-inducible factor 1-alpha (HIF-1α) and the extracellular adenosine axis was observed. TLR3 stimulation synergized with adenosine receptor A2b on PCa cells, and induced a strong production of lactate, exacerbating the Warburg effect. Moreover, stimulation of benign prostate cells with poly I:C reduced lactate secretion, a characteristic typical of the neoplastic transformation. CONCLUSION: TLR3 stimulation promotes metabolic adaptations likely involved in the mechanisms of disease onset and progression.
Assuntos
Glucose/metabolismo , Próstata/metabolismo , Próstata/patologia , Neoplasias da Próstata/metabolismo , Receptor 3 Toll-Like/metabolismo , Adenosina/metabolismo , Linhagem Celular Tumoral , Progressão da Doença , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Masculino , Células PC-3 , Poli I-C/metabolismo , Neoplasias da Próstata/patologia , Receptores Purinérgicos P1/metabolismoRESUMO
Enzymes of intermediary metabolism are often reported to have moonlighting functions as RNA-binding proteins and have regulatory roles beyond their primary activities. Human serine hydroxymethyltransferase (SHMT) is essential for the one-carbon metabolism, which sustains growth and proliferation in normal and tumour cells. Here, we characterize the RNA-binding function of cytosolic SHMT (SHMT1) in vitro and using cancer cell models. We show that SHMT1 controls the expression of its mitochondrial counterpart (SHMT2) by binding to the 5'untranslated region of the SHMT2 transcript (UTR2). Importantly, binding to RNA is modulated by metabolites in vitro and the formation of the SHMT1-UTR2 complex inhibits the serine cleavage activity of the SHMT1, without affecting the reverse reaction. Transfection of UTR2 in cancer cells controls SHMT1 activity and reduces cell viability. We propose a novel mechanism of SHMT regulation, which interconnects RNA and metabolites levels to control the cross-talk between cytosolic and mitochondrial compartments of serine metabolism.
Assuntos
Citosol/enzimologia , Glicina Hidroximetiltransferase/genética , Mitocôndrias/enzimologia , Proteínas de Ligação a RNA/genética , Serina/metabolismo , Regiões 5' não Traduzidas , Compartimento Celular/genética , Linhagem Celular Tumoral , Proliferação de Células , Fibroblastos/citologia , Fibroblastos/enzimologia , Regulação da Expressão Gênica , Glicina Hidroximetiltransferase/metabolismo , Humanos , Linfócitos/citologia , Linfócitos/enzimologia , Mitocôndrias/genética , Ligação Proteica , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Proteínas de Ligação a RNA/metabolismoRESUMO
Cancer cells reprogramme one-carbon metabolism (OCM) to sustain growth and proliferation. Depending on cell demands, serine hydroxymethyltransferase (SHMT) dynamically changes the fluxes of OCM by reversibly converting serine and tetrahydrofolate (THF) into 5,10-methylene-THF and glycine. SHMT is a tetrameric enzyme that mainly exists in three isoforms; two localize in the cytosol (SHMT1/SHMT2α) and one (SHMT2) in the mitochondria. Both the cytosolic isoforms can also translocate to the nucleus to sustain de novo thymidylate synthesis and support cell proliferation. Finally, the expression levels of the different isoforms are regulated to a certain extent by a yet unknown crosstalk mechanism. We have designed and fully characterized a set of three SHMT1 mutants, which uncouple the oligomeric state of the enzyme from its catalytic activity. We have then investigated the effects of the mutations on SHMT1 nuclear localization, cell viability and crosstalk in lung cancer cells (A549; H1299). Our data reveal that in these cell lines de novo thymidylate synthesis requires SHMT1 to be active, regardless of its oligomeric state. We have also confirmed that the crosstalk between the cytosolic and mitochondrial SHMT actually takes place and regulates the expression of the two isoforms. Apparently, the crosstalk mechanism is independent from the oligomeric state and the catalytic activity of SHMT1. DATABASE: Structural data are available in the PDB under the accession number 6FL5.
Assuntos
Núcleo Celular/metabolismo , Glicina Hidroximetiltransferase/metabolismo , Neoplasias Pulmonares/metabolismo , Proteínas Mutantes/metabolismo , Serina/metabolismo , Timidina Monofosfato/metabolismo , Proliferação de Células , Cristalografia por Raios X , Glicina Hidroximetiltransferase/química , Glicina Hidroximetiltransferase/genética , Humanos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , Proteínas Mutantes/química , Proteínas Mutantes/genética , Mutação , Conformação Proteica , Isoformas de Proteínas , Células Tumorais CultivadasRESUMO
Serine hydroxymethyltransferase (SHMT) is a pivotal enzyme in one-carbon metabolism that catalyses the reversible conversion of serine and tetrahydrofolate into glycine and methylenetetrahydrofolate. It exists in cytosolic (SHMT1) and mitochondrial (SHMT2) isoforms. Research on one-carbon metabolism in cancer cell lines has shown that SHMT1 preferentially catalyses serine synthesis, whereas in mitochondria SHMT2 is involved in serine breakdown. Recent research has focused on the identification of inhibitors that bind at the folate pocket. We have previously found that a representative derivative of the pyrazolopyran scaffold, namely 2.12, inhibits both SHMT isoforms, with a preference for SHMT1, causing apoptosis in lung cancer cell lines. Here we show that the affinity of 2.12 for SHMT depends on the identity of the amino acid substrate bound to the enzyme. The dissociation constant of 2.12 is 50-fold lower when it binds to SHMT1 enzyme-serine complex, as compared to the enzyme-glycine complex. Evidence is presented for a similar behaviour of compound 2.12 in the cellular environment. These findings suggest that the presence and identity of the amino acid substrate should be considered when designing SHMT inhibitors. Moreover, our data provide the proof-of-concept that SHMT inhibitors selectively targeting the directionality of one-carbon metabolism flux could be designed.
Assuntos
Inibidores Enzimáticos/farmacologia , Glicina Hidroximetiltransferase/antagonistas & inibidores , Glicina Hidroximetiltransferase/química , Glicina/química , Piranos/farmacologia , Pirazóis/farmacologia , Serina/química , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Inibidores Enzimáticos/metabolismo , Humanos , Ligação de Hidrogênio , Neoplasias Pulmonares/patologia , Piranos/química , Pirazóis/química , Espectrometria de Fluorescência , Especificidade por SubstratoRESUMO
Nonylphenol (NP) and octylphenol (OP) are pervasive environmental contaminants belonging to the broader class of compounds known as alkylphenols, with potential human toxic effects. Classified as "xenoestrogens," NP and OP are able to interfere with the cell endocrine physiology via a direct interaction with the estrogen receptors. Here, using HepG2 cells in culture, the changes of the cell redox balance and mitochondrial activity induced by OP and NP have been investigated at µM concentrations, largely below those provoking acute toxicity, as those typical of environmental contaminants. Following 24 h cell exposure to both OP and NP, ROS production appeared significantly increased (p ≤ 0.01), together with the production of higher NO oxides (p = 0.003) and peroxynitrated protein-derivatives (NP versus CTR, p = 0.003). The mitochondrial proton electrochemical potential gradient instead was decreased (p ≤ 0.05), as the oxygen consumption by complex IV, particularly following incubation with NP (NP versus CTR, p = 0.017). Consistently, the RT-PCR and Western blot analyses proved that the OP and NP can modulate to a different extent the expression of the inducible NOS (NP versus CTR, p ≤ 0.01) and the endothelial NOS (OP versus CTR, p ≤ 0.05), with a significant variation of the coupling efficiency of the latter (NP versus CTR, p ≤ 0.05), a finding that may provide a novel clue to understand the specific xenoestrogenic properties of OP and NP.
Assuntos
Óxido Nítrico/metabolismo , Fenóis/química , Humanos , Oxirredução , Transdução de SinaisRESUMO
A growing body of evidence suggests the consumption of high-fat diet (HFD) during pregnancy to model maternal obesity and the associated increase in oxidative stress (OS), might act as powerful prenatal stressors, leading to adult stress-related metabolic or behavioral disorders. We hypothesized that administration of antioxidants throughout gestation might counteract the negative effects of prenatal exposure to metabolic challenges (maternal HFD feeding during pregnancy) on the developing fetus. In this study, female C57BL/6J mice were fed HFD for 13 weeks (from 5-weeks of age until delivery) and were exposed to the N-acetyl-cysteine (NAC) antioxidant from 10-weeks of age until right before delivery. Body weight of the offspring was assessed following birth, up to weaning and at adulthood. The metabolic, neuroendocrine and emotional profile of the adult offspring was tested at 3-months of age. Prenatal HFD increased mother's body weight and offspring's weight at the time of weaning, when administered in conjunction with NAC. In females, NAC administration reduced high levels of leptin resulting from prenatal HFD. Prenatal NAC administration also resulted in greater glucose tolerance and insulin sensitivity while increasing adiponectin levels, as well as increasing exploratory behavior, an effect accompanied by reduced plasma corticosterone levels in response to restraint stress. Analysis of glutathione levels in the hypothalamus and in brown adipose tissue indicates that, while HFD administration to pregnant dams led to reduced levels of glutathione in the offspring, as in the male hypothalamus, NAC was able to revert this effect and to increase glutathione levels both in the periphery (Brown Adipose Tissue, both males and females) and in the central nervous system (males). Overall, results from this study indicate that the body redox milieu should be tightly regulated during fetal life and that buffering OS during pregnancy can have important long-term consequences on metabolic and behavioral endpoints.
RESUMO
High levels of circulating lipoprotein constitute a risk factor for cardiovascular diseases, and in this context, the specific role of the very-low-density lipoproteins (VLDL) is poorly understood. The response of human umbilical vein endothelial cells (HUVEC) to VLDL exposure was studied, especially focusing on the pathways involved in alteration of redox homeostasis and nitric oxide (NO) bioavailability. The results obtained by the analysis of the expression level of genes implicated in the NO metabolism and oxidative stress response indicated a strong activation of inducible NO synthase (iNOS) upon 24 h exposure to VLDL, particularly if these have been preventively oxidised. Simultaneously, both mRNA and protein expression of endothelial NO synthase (eNOS) were decreased and its phosphorylation pattern, at the key residues Tyr495 and Ser1177, strongly suggested the occurrence of the eNOS uncoupling. The results are consistent with the observed increased production of nitrites and nitrates (NOx), reactive oxygen species (ROS), 3-nitrotyrosine (3-NT), and, at mitochondrial level, a deficit in mitochondrial O2 consumption. Altogether, these data suggest that the VLDL, particularly if oxidised, when allowed to persist in contact with endothelial cells, strongly alter NO bioavailability, affecting redox homeostasis and mitochondrial function.
Assuntos
Células Endoteliais da Veia Umbilical Humana/metabolismo , Lipoproteínas VLDL/metabolismo , Óxido Nítrico/metabolismo , Homeostase , Humanos , Espécies Reativas de Oxigênio , Transdução de SinaisRESUMO
This research provides a cautionary example when evaluating changes in behavioral end points with respect to postulated pharmacologic activity. Various small molecule substrate mimetic protein tyrosine phosphatase 1B (PTP1B) inhibitors were investigated as pharmacologic agents for decreasing food consumption using intranasal (IN) dosing as a means for direct nose-to-brain delivery along the olfactory/trigeminal nerve pathways. Although food consumption was decreased in diet-induced obese (DIO) mice, nasal discharge was observed. Studies were conducted to investigate local effects on the nasal airway and to develop structure-activity relationships. Intranasal administration of PTP1B inhibitors at ≥0.03 mg/d to DIO mice produced dose-dependent injury to various cell types of the nasal epithelia. Protein tyrosine phosphatase 1B inhibitors with calculated log octanol >3.0 were the most toxic. Whereas a pharmacologically inactive analog of a PTP1B inhibitor produced nasal injury, along with decreased food consumption, the marketed IN drug ketorolac produced no lesions at the same dose of 0.3 mg/d and only minor changes at 3 mg/d. Rat skin fibroblast cells were exposed in vitro to PTP1B inhibitors, ketorolac, paraquat, and the detergent sodium dodecylbenzene sulfonate (NDS) followed by measures of cytotoxicity. The most potent PTP1B inhibitors were similar to NDS, whereas ketorolac was the least toxic compound. Cytotoxic potency in vitro was similar to in vivo. In conclusion, PTP1B inhibitors injured nasal epithelium through a mechanism independent of PTP1B inhibition and likely due to nonspecific cytotoxicity such as disruption of the cell membrane. Decreased food consumption in DIO mice was due to toxicity rather than a pharmacologic mode of action.
Assuntos
Inibidores Enzimáticos/efeitos adversos , Inibidores Enzimáticos/toxicidade , Mucosa Nasal/efeitos dos fármacos , Mucosa Nasal/lesões , Obesidade/tratamento farmacológico , Proteína Tirosina Fosfatase não Receptora Tipo 1/antagonistas & inibidores , Administração Intranasal , Animais , Células Cultivadas , Relação Dose-Resposta a Droga , Ingestão de Alimentos/efeitos dos fármacos , Inibidores Enzimáticos/administração & dosagem , Fibroblastos/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mucosa Nasal/citologia , Ratos , Relação Estrutura-AtividadeRESUMO
Cocaine abuse has long been known to cause morbidity and mortality due to its cardiovascular toxic effects. The pathogenesis of the cardiovascular toxicity of cocaine use has been largely reviewed, and the most recent data indicate a fundamental role of oxidative stress in cocaine-induced cardiovascular toxicity, indicating that mitochondrial dysfunction is involved in the mechanisms of oxidative stress. The comprehension of the mechanisms involving mitochondrial dysfunction could help in selecting the most appropriate mitochondria injury biological marker, such as superoxide dismutase-2 activity and glutathionylated hemoglobin. The potential use of modulators of oxidative stress (mitoubiquinone, the short-chain quinone idebenone, and allopurinol) in the treatment of cocaine cardiotoxic effects is also suggested to promote further investigations on these potential mitochondria-targeted antioxidant strategies.
Assuntos
Doenças Cardiovasculares/metabolismo , Transtornos Relacionados ao Uso de Cocaína/metabolismo , Cocaína/toxicidade , Mitocôndrias Cardíacas/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Animais , Doenças Cardiovasculares/induzido quimicamente , Doenças Cardiovasculares/patologia , Transtornos Relacionados ao Uso de Cocaína/patologia , Humanos , Mitocôndrias Cardíacas/patologia , Superóxido Dismutase/metabolismoRESUMO
Here we have collected evidence suggesting that chronic changes in the NO homeostasis and the rise of reactive oxygen species bioavailability can contribute to cell dysfunction in Leber's hereditary optic neuropathy (LHON) patients. We report that peripheral blood mononuclear cells (PBMCs), derived from a female LHON patient with bilateral reduced vision and carrying the pathogenic mutation 11778/ND4, display increased levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS), as revealed by flow cytometry, fluorometric measurements of nitrite/nitrate, and 3-nitrotyrosine immunodetection. Moreover, viability assays with the tetrazolium dye MTT showed that lymphoblasts from the same patient are more sensitive to prolonged NO exposure, leading to cell death. Taken together these findings suggest that oxidative and nitrosative stress cooperatively play an important role in driving LHON pathology when excess NO remains available over time in the cell environment.
Assuntos
Atrofia Óptica Hereditária de Leber/patologia , Espécies Reativas de Nitrogênio/química , Espécies Reativas de Oxigênio/química , Trifosfato de Adenosina/química , Adulto , Sobrevivência Celular , Feminino , Citometria de Fluxo , Fluorometria , Humanos , Leucócitos Mononucleares/metabolismo , Linfócitos/citologia , Mutação , Nitritos/química , Nitrogênio , Atrofia Óptica Hereditária de Leber/metabolismo , Estresse Oxidativo , Oxigênio , Consumo de Oxigênio , Tirosina/análogos & derivados , Tirosina/químicaRESUMO
The 7WD4 and 7PA2 cell lines, widely used as cellular models for Alzheimer's disease (AD), have been used to investigate the effects of amyloid-ß protein precursor overexpression and amyloid-ß (Aß) oligomer accumulation on mitochondrial function. Under standard culture conditions, both cell lines, compared to Chinese hamster ovary (CHO) control cells, displayed an ~5% decrease of O2 respiration as sustained by endogenous substrates. Functional impairment of the respiratory chain was found distributed among the protein complexes, though more evident at the level of complex I and complex IV. Measurements of ATP showed that its synthesis by oxidative phosphorylation is decreased in 7WD4 and 7PA2 cells by ~25%, this loss being partly compensated by glycolysis (Warburg effect). Compensation proved to be more efficient in 7WD4 than in 7PA2 cells, the latter cell line displaying the highest reactive oxygen species production. The strongest deficit was observed in mitochondrial membrane potential that is almost 40% and 60% lower in 7WD4 and 7PA2 cells, respectively, in comparison to CHO controls. All functional parameters point to a severe bioenergetic impairment of the AD cells, with the extent of mitochondrial dysfunction being correlated to the accumulation of Aß peptides and oligomers.
Assuntos
Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/fisiologia , Mitocôndrias/metabolismo , Consumo de Oxigênio/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Doença de Alzheimer/fisiopatologia , Animais , Células CHO , Linhagem Celular , Cricetinae , Cricetulus , Humanos , Mitocôndrias/patologiaRESUMO
Extending our previous observations, we have shown on HaCat cells that melatonin, at ~10-9 M concentration, transiently raises not only the expression of the neuronal nitric oxide synthase (nNOS) mRNA, but also the nNOS protein synthesis and the nitric oxide oxidation products, nitrite and nitrate. Interestingly, from the cell bioenergetic point of view, the activated NO-related chemistry induces a mild decrease of the oxidative phosphorylation (OXPHOS) efficiency, paralleled by a depression of the mitochondrial membrane potential. The OXPHOS depression is apparently balanced by glycolysis. The mitochondrial effects described have been detected only at nanomolar concentration of melatonin and within a time window of a few hours' incubation; both findings compatible with the melatonin circadian cycle.
Assuntos
Ritmo Circadiano , Melatonina/metabolismo , Mitocôndrias/metabolismo , Óxido Nítrico/metabolismo , Trifosfato de Adenosina/biossíntese , Linhagem Celular , Respiração Celular/efeitos dos fármacos , Ritmo Circadiano/efeitos dos fármacos , Humanos , Queratinócitos/efeitos dos fármacos , Queratinócitos/metabolismo , Lactatos/metabolismo , Melatonina/farmacologia , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Modelos Biológicos , Óxido Nítrico Sintase Tipo I/metabolismo , Fosforilação Oxidativa/efeitos dos fármacos , Fatores de TempoRESUMO
Nitric oxide (NO) reacts with Complex I and cytochrome c oxidase (CcOX, Complex IV), inducing detrimental or cytoprotective effects. Two alternative reaction pathways (PWs) have been described whereby NO reacts with CcOX, producing either a relatively labile nitrite-bound derivative (CcOX-NO(2) (-), PW1) or a more stable nitrosyl-derivative (CcOX-NO, PW2). The two derivatives are both inhibited, displaying different persistency and O(2) competitiveness. In the mitochondrion, during turnover with O(2), one pathway prevails over the other one depending on NO, cytochrome c(2+) and O(2) concentration. High cytochrome c(2+), and low O(2) proved to be crucial in favoring CcOX nitrosylation, whereas under-standard cell-culture conditions formation of the nitrite derivative prevails. All together, these findings suggest that NO can modulate physiologically the mitochondrial respiratory/OXPHOS efficiency, eventually being converted to nitrite by CcOX, without cell detrimental effects. It is worthy to point out that nitrite, far from being a simple oxidation byproduct, represents a source of NO particularly important in view of the NO cell homeostasis, the NO production depends on the NO synthases whose activity is controlled by different stimuli/effectors; relevant to its bioavailability, NO is also produced by recycling cell/body nitrite. Bioenergetic parameters, such as mitochondrial ΔΨ, lactate, and ATP production, have been assayed in several cell lines, in the presence of endogenous or exogenous NO and the evidence collected suggests a crucial interplay between CcOX and NO with important energetic implications.