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1.
J Cell Sci ; 135(5)2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33414166

RESUMO

Ferroptosis is a regulated, non-apoptotic form of cell death, characterized by hydroxy-peroxidation of discrete phospholipid hydroperoxides, particularly hydroperoxyl (Hp) forms of arachidonoyl- and adrenoyl-phosphatidylethanolamine, with a downstream cascade of oxidative damage to membrane lipids, proteins and DNA, culminating in cell death. We recently showed that human trophoblasts are particularly sensitive to ferroptosis caused by depletion or inhibition of glutathione peroxidase 4 (GPX4) or the lipase PLA2G6. Here, we show that trophoblastic ferroptosis is accompanied by a dramatic change in the trophoblast plasma membrane, with macro-blebbing and vesiculation. Immunofluorescence revealed that ferroptotic cell-derived blebs stained positive for F-actin, but negative for cytoplasmic organelle markers. Transfer of conditioned medium that contained detached macrovesicles or co-culture of wild-type target cells with blebbing cells did not stimulate ferroptosis in target cells. Molecular modeling showed that the presence of Hp-phosphatidylethanolamine in the cell membrane promoted its cell ability to be stretched. Together, our data establish that membrane macro-blebbing is characteristic of trophoblast ferroptosis and can serve as a useful marker of this process. Whether or not these blebs are physiologically functional remains to be established.

3.
ACS Cent Sci ; 6(10): 1772-1788, 2020 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-33145414

RESUMO

The development of a fluorescent probe for a specific metal has required exquisite design, synthesis, and optimization of fluorogenic molecules endowed with chelating moieties with heteroatoms. These probes are generally chelation- or reactivity-based. Catalysis-based fluorescent probes have the potential to be more sensitive; however, catalytic methods with a biocompatible fluorescence turn-on switch are rare. Here, we have exploited ligand-accelerated metal catalysis to repurpose known fluorescent probes for different metals, a new approach in probe development. We used the cleavage of allylic and propargylic ethers as platforms that were previously designed for palladium. After a single experiment that combinatorially examined >800 reactions with two variables (metal and ligand) for each ether, we discovered a platinum- or copper-selective method with the ligand effect of specific phosphines. Both metal-ligand systems were previously unknown and afforded strong signals owing to catalytic turnover. The fluorometric technologies were applied to geological, pharmaceutical, serum, and live cell samples and were used to discover that platinum accumulates in lysosomes in cisplatin-resistant cells in a manner that appears to be independent of copper distribution. The use of ligand-accelerated catalysis may present a new blueprint for engineering metal selectivity in probe development.

4.
Proc Natl Acad Sci U S A ; 117(44): 27319-27328, 2020 11 03.
Artigo em Inglês | MEDLINE | ID: mdl-33087576

RESUMO

The recently identified ferroptotic cell death is characterized by excessive accumulation of hydroperoxy-arachidonoyl (C20:4)- or adrenoyl (C22:4)- phosphatidylethanolamine (Hp-PE). The selenium-dependent glutathione peroxidase 4 (GPX4) inhibits ferroptosis, converting unstable ferroptotic lipid hydroperoxides to nontoxic lipid alcohols in a tissue-specific manner. While placental oxidative stress and lipotoxicity are hallmarks of placental dysfunction, the possible role of ferroptosis in placental dysfunction is largely unknown. We found that spontaneous preterm birth is associated with ferroptosis and that inhibition of GPX4 causes ferroptotic injury in primary human trophoblasts and during mouse pregnancy. Importantly, we uncovered a role for the phospholipase PLA2G6 (PNPLA9, iPLA2beta), known to metabolize Hp-PE to lyso-PE and oxidized fatty acid, in mitigating ferroptosis induced by GPX4 inhibition in vitro or by hypoxia/reoxygenation injury in vivo. Together, we identified ferroptosis signaling in the human and mouse placenta, established a role for PLA2G6 in attenuating trophoblastic ferroptosis, and provided mechanistic insights into the ill-defined placental lipotoxicity that may inspire PLA2G6-targeted therapeutic strategies.

5.
Redox Biol ; 37: 101695, 2020 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-32905883

RESUMO

Convergent evidence implicates impaired mitochondrial function and α-Synuclein accumulation as critical upstream events in the pathogenesis of Parkinson's disease, but comparatively little is known about how these factors interact to provoke neurodegeneration. We previously showed that α-Synuclein knockdown protected rat substantia nigra dopaminergic neurons from systemic exposure to the mitochondrial complex I inhibitor rotenone. Here we show that motor abnormalities prior to neuronal loss in this model are associated with extensive α-Synuclein-dependent cellular thiol oxidation. In order to elucidate the underlying events in vivo we constructed novel transgenic zebrafish that co-express, in dopaminergic neurons: (i) human α-Synuclein at levels insufficient to provoke neurodegeneration or neurobehavioral abnormalities; and (ii) genetically-encoded ratiometric fluorescent biosensors to detect cytoplasmic peroxide flux and glutathione oxidation. Live intravital imaging of the intact zebrafish CNS at cellular resolution showed unequivocally that α-Synuclein amplified dynamic cytoplasmic peroxide flux in dopaminergic neurons following exposure to the mitochondrial complex I inhibitors MPP+ or rotenone. This effect was robust and clearly evident following either acute or prolonged exposure to each inhibitor. In addition, disturbance of the resting glutathione redox potential following exogenous hydrogen peroxide challenge was augmented by α-Synuclein. Together these data show that α-Synuclein is a critical determinant of the redox consequences of mitochondrial dysfunction in dopaminergic neurons. The findings are important because the mechanisms underlying α-Synuclein-dependent reactive oxygen species fluxes and antioxidant suppression might provide a pharmacological target in Parkinson's disease to prevent progression from mitochondrial dysfunction and oxidative stress to cell death.

6.
medRxiv ; 2020 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-32817968

RESUMO

SARS-CoV-2 pneumonia may induce an aberrant immune response with brisk recruitment of myeloid cells into the lower respiratory tract, which may contribute to morbidity and mortality. We describe endotracheal aspirate samples from seven patients with SARS-CoV-2 pneumonia requiring mechanical ventilation. We note SARS-CoV-2 virions within lower respiratory tract myeloid cells shown by electron tomography, immunofluorescence confocal imaging, and immuno-electron microscopy. Endotracheal aspirates are primarily composed of mononuclear and polymorphonuclear leukocytes. These myeloid cells that harbor virus are frequently positive for CD14 and/or CD16 and most display an inflammatory phenotype marked by expression of IL-6 and tissue factor mRNA transcript and protein expression.

7.
Sci Transl Med ; 12(553)2020 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-32718989

RESUMO

Patients with insulin resistance have high risk of cardiovascular disease such as myocardial infarction (MI). However, it is not known whether MI can initiate or aggravate insulin resistance. We observed that patients with ST-elevation MI and mice with MI had de novo hyperglycemia and features of insulin resistance, respectively. In mouse models of both myocardial and skeletal muscle injury, we observed that the number of visceral adipose tissue (VAT)-resident macrophages decreased because of apoptosis after these distant organ injuries. Patients displayed a similar decrease in VAT-resident macrophage numbers and developed systemic insulin resistance after ST-elevation MI. Loss of VAT-resident macrophages after MI injury led to systemic insulin resistance in non-diabetic mice. Danger signaling-associated protein high mobility group box 1 was released by the dead myocardium after MI in rodents and triggered macrophage apoptosis via Toll-like receptor 4. The VAT-resident macrophage population in the steady state in mice was transcriptomically distinct from macrophages in the brain, skin, kidney, bone marrow, lungs, and liver and was derived from hematopoietic progenitor cells just after birth. Mechanistically, VAT-resident macrophage apoptosis and de novo insulin resistance in mouse models of MI were linked to diminished concentrations of macrophage colony-stimulating factor and adiponectin. Collectively, these findings demonstrate a previously unappreciated role of adipose tissue-resident macrophages in sensing remote organ injury and promoting MI pathogenesis.

8.
Artigo em Inglês | MEDLINE | ID: mdl-32585075

RESUMO

Hydrogen peroxide (H2 O2 ) mediates the biology of wound healing, apoptosis, inflammation, etc. H2 O2 has been fluorometrically imaged with protein- or small-molecule-based probes. However, only protein-based probes have afforded temporal insights within seconds. Small-molecule-based electrophilic probes for H2 O2 require many minutes for a sufficient response in biological systems. Here, we report a fluorogenic probe that selectively undergoes a [2,3]-sigmatropic rearrangement (seleno-Mislow-Evans rearrangement) with H2 O2 , followed by acetal hydrolysis, to produce a green fluorescent molecule in seconds. Unlike other electrophilic probes, the current probe acts as a nucleophile. The fast kinetics enabled real-time imaging of H2 O2 produced in endothelial cells in 8 seconds (much earlier than previously shown) and H2 O2 in a zebrafish wound healing model. This work may provide a platform for endogenous H2 O2 detection in real time with chemical probes.

9.
Proc Natl Acad Sci U S A ; 117(25): 14376-14385, 2020 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-32513718

RESUMO

Temporally harmonized elimination of damaged or unnecessary organelles and cells is a prerequisite of health. Under Type 2 inflammatory conditions, human airway epithelial cells (HAECs) generate proferroptotic hydroperoxy-arachidonoyl-phosphatidylethanolamines (HpETE-PEs) as proximate death signals. Production of 15-HpETE-PE depends on activation of 15-lipoxygenase-1 (15LO1) in complex with PE-binding protein-1 (PEBP1). We hypothesized that cellular membrane damage induced by these proferroptotic phospholipids triggers compensatory prosurvival pathways, and in particular autophagic pathways, to prevent cell elimination through programmed death. We discovered that PEBP1 is pivotal to driving dynamic interactions with both proferroptotic 15LO1 and the autophagic protein microtubule-associated light chain-3 (LC3). Further, the 15LO1-PEBP1-generated ferroptotic phospholipid, 15-HpETE-PE, promoted LC3-I lipidation to stimulate autophagy. This concurrent activation of autophagy protects cells from ferroptotic death and release of mitochondrial DNA. Similar findings are observed in Type 2 Hi asthma, where high levels of both 15LO1-PEBP1 and LC3-II are seen in HAECs, in association with low bronchoalveolar lavage fluid mitochondrial DNA and more severe disease. The concomitant activation of ferroptosis and autophagy by 15LO1-PEBP1 complexes and their hydroperoxy-phospholipids reveals a pathobiologic pathway relevant to asthma and amenable to therapeutic targeting.


Assuntos
Araquidonato 15-Lipoxigenase/metabolismo , Asma/imunologia , Autofagia/imunologia , Células Epiteliais/patologia , Ferroptose/imunologia , Proteína de Ligação a Fosfatidiletanolamina/metabolismo , Adulto , Animais , Asma/diagnóstico , Asma/patologia , Líquido da Lavagem Broncoalveolar/citologia , Linhagem Celular , Sobrevivência Celular/imunologia , Células Epiteliais/imunologia , Feminino , Técnicas de Inativação de Genes , Humanos , Ácidos Hidroxieicosatetraenoicos/imunologia , Ácidos Hidroxieicosatetraenoicos/metabolismo , Interleucina-13/imunologia , Interleucina-13/metabolismo , Masculino , Camundongos , Proteínas Associadas aos Microtúbulos/metabolismo , Simulação de Dinâmica Molecular , Proteína de Ligação a Fosfatidiletanolamina/genética , Fosfatidiletanolaminas/imunologia , Fosfatidiletanolaminas/metabolismo , Cultura Primária de Células , Ligação Proteica/imunologia , Índice de Gravidade de Doença
10.
FASEB J ; 34(5): 7192-7207, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32274853

RESUMO

Mutations in ganglioside-induced differentiation-associated protein 1 (GDAP1) alter mitochondrial morphology and result in several subtypes of the inherited peripheral neuropathy Charcot-Marie-Tooth disease; however, the mechanism by which GDAP1 functions has remained elusive. GDAP1 contains primary sequence homology to the GST superfamily; however, the question of whether GDAP1 is an active GST has not been clearly resolved. Here, we present biochemical evidence, suggesting that GDAP1 has lost the ability to bind glutathione without a loss of substrate binding activity. We have revealed that the α-loop, located within the H-site motif is the primary determinant for substrate binding. Using structural data of GDAP1, we have found that critical residues and configurations in the G-site which canonically interact with glutathione are altered in GDAP1, rendering it incapable of binding glutathione. Last, we have found that the overexpression of GDAP1 in HeLa cells results in a mitochondrial phenotype which is distinct from oxidative stress-induced mitochondrial fragmentation. This phenotype is dependent on the presence of the transmembrane domain, as well as a unique hydrophobic domain that is not found in canonical GSTs. Together, we data point toward a non-enzymatic role for GDAP1, such as a sensor or receptor.

11.
Elife ; 92020 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-32180546

RESUMO

Mitochondrial dysfunction is implicated in the pathogenesis of multiple neurological diseases, but elucidation of underlying mechanisms is limited experimentally by the inability to damage specific mitochondria in defined neuronal groups. We developed a precision chemoptogenetic approach to target neuronal mitochondria in the intact nervous system in vivo. MG2I, a chemical fluorogen, produces singlet oxygen when bound to the fluorogen-activating protein dL5** and exposed to far-red light. Transgenic zebrafish expressing dL5** within neuronal mitochondria showed dramatic MG2I- and light-dependent neurobehavioral deficits, caused by neuronal bioenergetic crisis and acute neuronal depolarization. These abnormalities resulted from loss of neuronal respiration, associated with mitochondrial fragmentation, swelling and elimination of cristae. Remaining cellular ultrastructure was preserved initially, but cellular pathology downstream of mitochondrial damage eventually culminated in neuronal death. Our work provides powerful new chemoptogenetic tools for investigating mitochondrial homeostasis and pathophysiology and shows a direct relationship between mitochondrial function, neuronal biogenetics and whole-animal behavior.

12.
Nat Chem Biol ; 16(3): 278-290, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32080625

RESUMO

Ferroptotic death is the penalty for losing control over three processes-iron metabolism, lipid peroxidation and thiol regulation-that are common in the pro-inflammatory environment where professional phagocytes fulfill their functions and yet survive. We hypothesized that redox reprogramming of 15-lipoxygenase (15-LOX) during the generation of pro-ferroptotic signal 15-hydroperoxy-eicosa-tetra-enoyl-phosphatidylethanolamine (15-HpETE-PE) modulates ferroptotic endurance. Here, we have discovered that inducible nitric oxide synthase (iNOS)/NO•-enrichment of activated M1 (but not alternatively activated M2) macrophages/microglia modulates susceptibility to ferroptosis. Genetic or pharmacologic depletion/inactivation of iNOS confers sensitivity on M1 cells, whereas NO• donors empower resistance of M2 cells to ferroptosis. In vivo, M1 phagocytes, in comparison to M2 phagocytes, exert higher resistance to pharmacologically induced ferroptosis. This resistance is diminished in iNOS-deficient cells in the pro-inflammatory conditions of brain trauma or the tumour microenvironment. The nitroxygenation of eicosatetraenoyl (ETE)-PE intermediates and oxidatively truncated species by NO• donors and/or suppression of NO• production by iNOS inhibitors represent a novel redox mechanism of regulation of ferroptosis in pro-inflammatory conditions.


Assuntos
Ferroptose/fisiologia , Macrófagos/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo , Animais , Araquidonato 15-Lipoxigenase/metabolismo , Araquidonato 15-Lipoxigenase/fisiologia , Morte Celular , Feminino , Ferro/metabolismo , Ferro/fisiologia , Leucotrienos/metabolismo , Peroxidação de Lipídeos/fisiologia , Peróxidos Lipídicos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microglia/metabolismo , Óxido Nítrico Sintase Tipo II/fisiologia , Oxirredução , Espécies Reativas de Oxigênio/metabolismo
13.
J Leukoc Biol ; 106(1): 57-81, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31071242

RESUMO

In addition to the known prominent role of polyunsaturated (phospho)lipids as structural blocks of biomembranes, there is an emerging understanding of another important function of these molecules as a highly diversified signaling language utilized for intra- and extracellular communications. Technological developments in high-resolution mass spectrometry facilitated the development of a new branch of metabolomics, redox lipidomics. Analysis of lipid peroxidation reactions has already identified specific enzymatic mechanisms responsible for the biosynthesis of several unique signals in response to inflammation and regulated cell death programs. Obtaining comprehensive information about millions of signals encoded by oxidized phospholipids, represented by thousands of interactive reactions and pleiotropic (patho)physiological effects, is a daunting task. However, there is still reasonable hope that significant discoveries, of at least some of the important contributors to the overall overwhelmingly complex network of interactions triggered by inflammation, will lead to the discovery of new small molecule regulators and therapeutic modalities. For example, suppression of the production of AA-derived pro-inflammatory mediators, HXA3 and LTB4, by an iPLA2 γ inhibitor, R-BEL, mitigated injury associated with the activation of pro-inflammatory processes in animals exposed to whole-body irradiation. Further, technological developments promise to make redox lipidomics a powerful approach in the arsenal of diagnostic and therapeutic instruments for personalized medicine of inflammatory diseases and conditions.


Assuntos
Apoptose , Inflamação/metabolismo , Lipidômica , Transdução de Sinais/fisiologia , Animais , Ácidos Graxos Insaturados/metabolismo , Humanos , Inflamação/etiologia , Ferro/metabolismo , Peroxidação de Lipídeos , Oxirredução , Irradiação Corporal Total
14.
Am J Physiol Lung Cell Mol Physiol ; 316(6): L1150-L1164, 2019 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-30892078

RESUMO

Pulmonary hypertension (PH) is a leading cause of death in sickle cell disease (SCD) patients. Hemolysis and oxidative stress contribute to SCD-associated PH. We have reported that the protein thrombospondin-1 (TSP1) is elevated in the plasma of patients with SCD and, by interacting with its receptor CD47, limits vasodilation of distal pulmonary arteries ex vivo. We hypothesized that the TSP1-CD47 interaction may promote PH in SCD. We found that TSP1 and CD47 are upregulated in the lungs of Berkeley (BERK) sickling (Sickle) mice and patients with SCD-associated PH. We then generated chimeric animals by transplanting BERK bone marrow into C57BL/6J (n = 24) and CD47 knockout (CD47KO, n = 27) mice. Right ventricular (RV) pressure was lower in fully engrafted Sickle-to-CD47KO than Sickle-to-C57BL/6J chimeras, as shown by the reduced maximum RV pressure (P = 0.013) and mean pulmonary artery pressure (P = 0.020). The afterload of the sickle-to-CD47KO chimeras was also lower, as shown by the diminished pulmonary vascular resistance (P = 0.024) and RV effective arterial elastance (P = 0.052). On myography, aortic segments from Sickle-to-CD47KO chimeras showed improved relaxation to acetylcholine. We hypothesized that, in SCD, TSP1-CD47 signaling promotes PH, in part, by increasing reactive oxygen species (ROS) generation. In human pulmonary artery endothelial cells, treatment with TSP1 stimulated ROS generation, which was abrogated by CD47 blockade. Explanted lungs of CD47KO chimeras had less vascular congestion and a smaller oxidative footprint. Our results show that genetic absence of CD47 ameliorates SCD-associated PH, which may be due to decreased ROS levels. Modulation of TSP1-CD47 may provide a new molecular approach to the treatment of SCD-associated PH.


Assuntos
Anemia Falciforme/patologia , Antígeno CD47/metabolismo , Hipertensão Pulmonar/patologia , Artéria Pulmonar/patologia , Trombospondina 1/metabolismo , Anemia Falciforme/genética , Animais , Antígeno CD47/antagonistas & inibidores , Antígeno CD47/genética , Células Cultivadas , Células Endoteliais/patologia , Humanos , Hipertensão Pulmonar/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Artéria Pulmonar/citologia , Espécies Reativas de Oxigênio/metabolismo , Função Ventricular Direita/fisiologia
15.
J Cereb Blood Flow Metab ; 39(5): 913-925, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-29192562

RESUMO

Decreased cerebral blood flow (CBF) after cardiac arrest (CA) contributes to secondary ischemic injury in infants and children. We previously reported cortical hypoperfusion with tissue hypoxia early in a pediatric rat model of asphyxial CA. In order to identify specific alterations as potential therapeutic targets to improve cortical hypoperfusion post-CA, we characterize the CBF alterations at the cortical microvascular level in vivo using multiphoton microscopy. We hypothesize that microvascular constriction and disturbances of capillary red blood cell (RBC) flow contribute to cortical hypoperfusion post-CA. After resuscitation from 9 min asphyxial CA, transient dilation of capillaries and venules at 5 min was followed by pial arteriolar constriction at 30 and 60 min (19.6 ± 1.3, 19.3 ± 1.2 µm at 30, 60 min vs. 22.0 ± 1.2 µm at baseline, p < 0.05). At the capillary level, microcirculatory disturbances were highly heterogeneous, with RBC stasis observed in 25.4% of capillaries at 30 min post-CA. Overall, the capillary plasma mean transit time was increased post-CA by 139.7 ± 51.5%, p < 0.05. In conclusion, pial arteriolar constriction, the no-reflow phenomenon and increased plasma transit time were observed post-CA. Our results detail the microvascular disturbances in a pediatric asphyxial CA model and provide a powerful platform for assessing specific vascular-targeted therapies.


Assuntos
Encéfalo/irrigação sanguínea , Circulação Cerebrovascular , Parada Cardíaca/complicações , Microcirculação , Fenômeno de não Refluxo/etiologia , Animais , Encéfalo/fisiopatologia , Parada Cardíaca/fisiopatologia , Masculino , Fenômeno de não Refluxo/fisiopatologia , Ratos Sprague-Dawley , Vasodilatação
16.
J Clin Invest ; 128(10): 4639-4653, 2018 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-30198910

RESUMO

Ferroptosis is a death program executed via selective oxidation of arachidonic acid-phosphatidylethanolamines (AA-PE) by 15-lipoxygenases. In mammalian cells and tissues, ferroptosis has been pathogenically associated with brain, kidney, and liver injury/diseases. We discovered that a prokaryotic bacterium, Pseudomonas aeruginosa, that does not contain AA-PE can express lipoxygenase (pLoxA), oxidize host AA-PE to 15-hydroperoxy-AA-PE (15-HOO-AA-PE), and trigger ferroptosis in human bronchial epithelial cells. Induction of ferroptosis by clinical P. aeruginosa isolates from patients with persistent lower respiratory tract infections was dependent on the level and enzymatic activity of pLoxA. Redox phospholipidomics revealed elevated levels of oxidized AA-PE in airway tissues from patients with cystic fibrosis (CF) but not with emphysema or CF without P. aeruginosa. We believe that the evolutionarily conserved mechanism of pLoxA-driven ferroptosis may represent a potential therapeutic target against P. aeruginosa-associated diseases such as CF and persistent lower respiratory tract infections.


Assuntos
Apoptose , Fibrose Cística/metabolismo , Fosfatidiletanolaminas/metabolismo , Infecções por Pseudomonas/metabolismo , Pseudomonas aeruginosa/metabolismo , Mucosa Respiratória/metabolismo , Infecções Respiratórias/metabolismo , Linhagem Celular , Fibrose Cística/microbiologia , Fibrose Cística/patologia , Células Epiteliais/metabolismo , Células Epiteliais/microbiologia , Células Epiteliais/patologia , Humanos , Infecções por Pseudomonas/patologia , Pseudomonas aeruginosa/patogenicidade , Mucosa Respiratória/microbiologia , Mucosa Respiratória/fisiologia , Infecções Respiratórias/microbiologia , Infecções Respiratórias/patologia
17.
J Neurosci ; 38(34): 7505-7515, 2018 08 22.
Artigo em Inglês | MEDLINE | ID: mdl-30030401

RESUMO

Dysregulation of mitochondrial biogenesis is implicated in the pathogenesis of neurodegenerative diseases such as Parkinson's disease (PD). However, it is not clear how mitochondrial biogenesis is regulated in neurons, with their unique compartmentalized anatomy and energetic demands. This is particularly relevant in PD because selectively vulnerable neurons feature long, highly arborized axons where degeneration initiates. We previously found that exposure of neurons to chronic, sublethal doses of rotenone, a complex I inhibitor linked to PD, causes early increases in mitochondrial density specifically in distal axons, suggesting possible upregulation of mitochondrial biogenesis within axons. Here, we directly evaluated for evidence of mitochondrial biogenesis in distal axons and examined whether PD-relevant stress causes compartmentalized alterations. Using BrdU labeling and imaging to quantify replicating mitochondrial DNA (mtDNA) in primary rat neurons (pooled from both sexes), we provide evidence of mtDNA replication in axons along with cell bodies and proximal dendrites. We found that exposure to chronic, sublethal rotenone increases mtDNA replication first in neurites and later extending to cell bodies, complementing our mitochondrial density data. Further, isolating axons from cell bodies and dendrites, we discovered that rotenone exposure upregulates mtDNA replication in distal axons. Utilizing superresolution stimulated emission depletion (STED) imaging, we identified mtDNA replication at sites of mitochondrial-endoplasmic reticulum contacts in axons. Our evidence suggests that mitochondrial biogenesis occurs not only in cell bodies, but also in distal axons, and is altered under PD-relevant stress conditions in an anatomically compartmentalized manner. We hypothesize that this contributes to vulnerability in neurodegenerative diseases.SIGNIFICANCE STATEMENT Mitochondrial biogenesis is crucial for maintaining mitochondrial and cellular health and has been linked to neurodegenerative disease pathogenesis. However, regulation of this process is poorly understood in CNS neurons, which rely on mitochondrial function for survival. Our findings offer fundamental insight into these regulatory mechanisms by demonstrating that replication of mitochondrial DNA, an essential precursor for biogenesis, can occur in distal regions of CNS neuron axons independent of the soma. Further, this process is upregulated specifically in axons as an early response to neurodegeneration-relevant stress. This is the first demonstration of the compartmentalized regulation of CNS neuronal mitochondrial biogenesis in response to stress and may prove a useful target in development of therapeutic strategies for neurodegenerative disease.


Assuntos
Axônios/ultraestrutura , Replicação do DNA , DNA Mitocondrial/biossíntese , Mitocôndrias/metabolismo , Biogênese de Organelas , Doença de Parkinson/metabolismo , Animais , Axônios/efeitos dos fármacos , Axônios/metabolismo , Córtex Cerebral/citologia , Replicação do DNA/efeitos dos fármacos , Complexo I de Transporte de Elétrons/antagonistas & inibidores , Complexo I de Transporte de Elétrons/metabolismo , Complexo IV da Cadeia de Transporte de Elétrons/análise , Retículo Endoplasmático/ultraestrutura , Feminino , Humanos , Masculino , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/ultraestrutura , Dinâmica Mitocondrial/efeitos dos fármacos , ATPases Mitocondriais Próton-Translocadoras/análise , Neuritos/efeitos dos fármacos , Neuritos/ultraestrutura , Neurônios/efeitos dos fármacos , Neurônios/ultraestrutura , Estresse Oxidativo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/análise , Ratos , Ratos Sprague-Dawley , Rotenona/toxicidade , Desacopladores/toxicidade
18.
J Cell Biol ; 217(5): 1567-1569, 2018 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-29653995

RESUMO

Light-sheet fluorescence microscopy methods that minimize photodamage are increasingly penetrant in biomedical research and currently comprise three distinct platforms. In this issue, Fadero et al. (2018. J. Cell Biol. https://doi.org/10.1083/jcb.201710087) describe a fourth approach termed "LITE microscopy," which is useful for extended imaging of specimens from cells to organisms.


Assuntos
Imageamento Tridimensional , Microscopia de Fluorescência/métodos , Animais , Caenorhabditis elegans/citologia , Caenorhabditis elegans/embriologia , Drosophila melanogaster/citologia
19.
Cell ; 171(3): 628-641.e26, 2017 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-29053969

RESUMO

Ferroptosis is a form of programmed cell death that is pathogenic to several acute and chronic diseases and executed via oxygenation of polyunsaturated phosphatidylethanolamines (PE) by 15-lipoxygenases (15-LO) that normally use free polyunsaturated fatty acids as substrates. Mechanisms of the altered 15-LO substrate specificity are enigmatic. We sought a common ferroptosis regulator for 15LO. We discovered that PEBP1, a scaffold protein inhibitor of protein kinase cascades, complexes with two 15LO isoforms, 15LO1 and 15LO2, and changes their substrate competence to generate hydroperoxy-PE. Inadequate reduction of hydroperoxy-PE due to insufficiency or dysfunction of a selenoperoxidase, GPX4, leads to ferroptosis. We demonstrated the importance of PEBP1-dependent regulatory mechanisms of ferroptotic death in airway epithelial cells in asthma, kidney epithelial cells in renal failure, and cortical and hippocampal neurons in brain trauma. As master regulators of ferroptotic cell death with profound implications for human disease, PEBP1/15LO complexes represent a new target for drug discovery.


Assuntos
Lesão Renal Aguda/patologia , Asma/patologia , Lesões Encefálicas Traumáticas/patologia , Morte Celular , Proteína de Ligação a Fosfatidiletanolamina/metabolismo , Lesão Renal Aguda/metabolismo , Animais , Apoptose , Asma/metabolismo , Lesões Encefálicas Traumáticas/metabolismo , Morte Celular/efeitos dos fármacos , Linhagem Celular , Humanos , Isoenzimas/metabolismo , Lipoxigenase/química , Lipoxigenase/metabolismo , Camundongos , Modelos Moleculares , Oxazolidinonas/farmacologia , Oxirredução , Proteína de Ligação a Fosfatidiletanolamina/química
20.
PLoS One ; 12(7): e0180486, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28686653

RESUMO

Whole-brain imaging is becoming a fundamental means of experimental insight; however, achieving subcellular resolution imagery in a reasonable time window has not been possible. We describe the first application of multicolor ribbon scanning confocal methods to collect high-resolution volume images of chemically cleared brains. We demonstrate that ribbon scanning collects images over ten times faster than conventional high speed confocal systems but with equivalent spectral and spatial resolution. Further, using this technology, we reconstruct large volumes of mouse brain infected with encephalitic alphaviruses and demonstrate that regions of the brain with abundant viral replication were inaccessible to vascular perfusion. This reveals that the destruction or collapse of large regions of brain micro vasculature may contribute to the severe disease caused by Venezuelan equine encephalitis virus. Visualization of this fundamental impact of infection would not be possible without sampling at subcellular resolution within large brain volumes.


Assuntos
Encéfalo/diagnóstico por imagem , Vírus da Encefalite Equina Venezuelana/patogenicidade , Encefalomielite Equina Venezuelana/diagnóstico por imagem , Microscopia Confocal/métodos , Animais , Encéfalo/fisiopatologia , Encéfalo/virologia , Callithrix/virologia , Vírus da Encefalite Equina Venezuelana/isolamento & purificação , Encefalomielite Equina Venezuelana/diagnóstico , Encefalomielite Equina Venezuelana/fisiopatologia , Encefalomielite Equina Venezuelana/virologia , Humanos , Camundongos , Neuroimagem/métodos , Ratos , Replicação Viral
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