RESUMO
In response to skeletal muscle contraction during exercise, paracrine factors coordinate tissue remodeling, which underlies this healthy adaptation. Here we describe a pH-sensing metabolite signal that initiates muscle remodeling upon exercise. In mice and humans, exercising skeletal muscle releases the mitochondrial metabolite succinate into the local interstitium and circulation. Selective secretion of succinate is facilitated by its transient protonation, which occurs upon muscle cell acidification. In the protonated monocarboxylic form, succinate is rendered a transport substrate for monocarboxylate transporter 1, which facilitates pH-gated release. Upon secretion, succinate signals via its cognate receptor SUCNR1 in non-myofibrillar cells in muscle tissue to control muscle-remodeling transcriptional programs. This succinate-SUCNR1 signaling is required for paracrine regulation of muscle innervation, muscle matrix remodeling, and muscle strength in response to exercise training. In sum, we define a bioenergetic sensor in muscle that utilizes intracellular pH and succinate to coordinate tissue adaptation to exercise.
Assuntos
Músculo Esquelético/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Ácido Succínico/metabolismo , Animais , Humanos , Concentração de Íons de Hidrogênio , Inflamação/metabolismo , Camundongos , Mitocôndrias/metabolismo , Transportadores de Ácidos Monocarboxílicos/metabolismo , Contração Muscular , Receptores Acoplados a Proteínas G/fisiologia , Transdução de Sinais , Succinatos/metabolismo , Simportadores/metabolismoRESUMO
Intestinal epithelial cell (IEC) damage by T cells contributes to graft-versus-host disease, inflammatory bowel disease and immune checkpoint blockade-mediated colitis. But little is known about the target cell-intrinsic features that affect disease severity. Here we identified disruption of oxidative phosphorylation and an increase in succinate levels in the IECs from several distinct in vivo models of T cell-mediated colitis. Metabolic flux studies, complemented by imaging and protein analyses, identified disruption of IEC-intrinsic succinate dehydrogenase A (SDHA), a component of mitochondrial complex II, in causing these metabolic alterations. The relevance of IEC-intrinsic SDHA in mediating disease severity was confirmed by complementary chemical and genetic experimental approaches and validated in human clinical samples. These data identify a critical role for the alteration of the IEC-specific mitochondrial complex II component SDHA in the regulation of the severity of T cell-mediated intestinal diseases.
Assuntos
Colite/enzimologia , Colo/enzimologia , Citotoxicidade Imunológica , Complexo II de Transporte de Elétrons/metabolismo , Células Epiteliais/enzimologia , Doença Enxerto-Hospedeiro/enzimologia , Mucosa Intestinal/enzimologia , Mitocôndrias/enzimologia , Linfócitos T/imunologia , Animais , Estudos de Casos e Controles , Comunicação Celular , Células Cultivadas , Colite/genética , Colite/imunologia , Colite/patologia , Colo/imunologia , Colo/ultraestrutura , Modelos Animais de Doenças , Complexo II de Transporte de Elétrons/genética , Células Epiteliais/imunologia , Células Epiteliais/ultraestrutura , Feminino , Doença Enxerto-Hospedeiro/genética , Doença Enxerto-Hospedeiro/imunologia , Doença Enxerto-Hospedeiro/patologia , Humanos , Imunidade nas Mucosas , Mucosa Intestinal/imunologia , Mucosa Intestinal/ultraestrutura , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mitocôndrias/imunologia , Mitocôndrias/ultraestrutura , Fosforilação Oxidativa , Ácido Succínico/metabolismo , Linfócitos T/metabolismoRESUMO
Krebs cycle intermediates traditionally link to oxidative phosphorylation whilst also making key cell components. It is now clear that some of these metabolites also act as signals. Succinate plays an important role in inflammatory, hypoxic, and metabolic signaling, while itaconate (from another Krebs cycle intermediate, cis-aconitate) has an anti-inflammatory role.
Assuntos
Ciclo do Ácido Cítrico/fisiologia , Succinatos/metabolismo , Ácido Succínico/metabolismo , Animais , Humanos , Transdução de SinaisRESUMO
The small intestinal tuft cell-ILC2 circuit mediates epithelial responses to intestinal helminths and protists by tuft cell chemosensory-like sensing and IL-25-mediated activation of lamina propria ILC2s. Small intestine ILC2s constitutively express the IL-25 receptor, which is negatively regulated by A20 (Tnfaip3). A20 deficiency in ILC2s spontaneously triggers the circuit and, unexpectedly, promotes adaptive small-intestinal lengthening and remodeling. Circuit activation occurs upon weaning and is enabled by dietary polysaccharides that render mice permissive for Tritrichomonas colonization, resulting in luminal accumulation of acetate and succinate, metabolites of the protist hydrogenosome. Tuft cells express GPR91, the succinate receptor, and dietary succinate, but not acetate, activates ILC2s via a tuft-, TRPM5-, and IL-25-dependent pathway. Also induced by parasitic helminths, circuit activation and small intestinal remodeling impairs infestation by new helminths, consistent with the phenomenon of concomitant immunity. We describe a metabolic sensing circuit that may have evolved to facilitate mutualistic responses to luminal pathosymbionts.
Assuntos
Intestino Delgado/fisiologia , Tritrichomonas/metabolismo , Acetatos/metabolismo , Animais , Fibras na Dieta/metabolismo , Metabolismo Energético , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Células Epiteliais/parasitologia , Interleucinas/genética , Interleucinas/metabolismo , Mucosa Intestinal/citologia , Intestino Delgado/microbiologia , Intestino Delgado/parasitologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microbiota , Plasmídeos/genética , Plasmídeos/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Receptores de Interleucina/metabolismo , Receptores de Interleucina-17/genética , Receptores de Interleucina-17/metabolismo , Ácido Succínico/metabolismo , Canais de Cátion TRPM/metabolismo , Tritrichomonas/crescimento & desenvolvimento , Proteína 3 Induzida por Fator de Necrose Tumoral alfa/genética , Proteína 3 Induzida por Fator de Necrose Tumoral alfa/metabolismoRESUMO
SUCNR1 is an auto- and paracrine sensor of the metabolic stress signal succinate. Using unsupervised molecular dynamics (MD) simulations (170.400 ns) and mutagenesis across human, mouse, and rat SUCNR1, we characterize how a five-arginine motif around the extracellular pole of TM-VI determines the initial capture of succinate in the extracellular vestibule (ECV) to either stay or move down to the orthosteric site. Metadynamics demonstrate low-energy succinate binding in both sites, with an energy barrier corresponding to an intermediate stage during which succinate, with an associated water cluster, unlocks the hydrogen-bond-stabilized conformationally constrained extracellular loop (ECL)-2b. Importantly, simultaneous binding of two succinate molecules through either a "sequential" or "bypassing" mode is a frequent endpoint. The mono-carboxylate NF-56-EJ40 antagonist enters SUCNR1 between TM-I and -II and does not unlock ECL-2b. It is proposed that occupancy of both high-affinity sites is required for selective activation of SUCNR1 by high local succinate concentrations.
Assuntos
Receptores Acoplados a Proteínas G , Ácido Succínico , Camundongos , Ratos , Animais , Humanos , Ácido Succínico/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Simulação de Dinâmica Molecular , Succinatos/metabolismo , Estresse FisiológicoRESUMO
Sirtuins are NAD(+)-dependent enzymes universally present in all organisms, where they play central roles in regulating numerous biological processes. Although early studies showed that sirtuins deacetylated lysines in a reaction that consumes NAD(+), more recent studies have revealed that these enzymes can remove a variety of acyl-lysine modifications. The specificities for varied acyl modifications may thus underlie the distinct roles of the different sirtuins within a given organism. This review summarizes the structure, chemistry, and substrate specificity of sirtuins with a focus on how different sirtuins recognize distinct substrates and thus carry out specific functions.
Assuntos
Histonas/química , NAD/química , Processamento de Proteína Pós-Traducional , Sirtuínas/química , Acilação , Expressão Gênica , Histonas/genética , Histonas/metabolismo , Humanos , Hidrólise , Cinética , Lipoilação , Modelos Moleculares , Ácido Mirístico/química , Ácido Mirístico/metabolismo , NAD/metabolismo , Plasmodium falciparum/química , Plasmodium falciparum/enzimologia , Estrutura Secundária de Proteína , Sirtuínas/genética , Sirtuínas/metabolismo , Especificidade por Substrato , Ácido Succínico/química , Ácido Succínico/metabolismo , Thermotoga maritima/química , Thermotoga maritima/enzimologiaRESUMO
Succinate is a signaling metabolite sensed extracellularly by succinate receptor 1 (SUNCR1). The accumulation of succinate in macrophages is known to activate a pro-inflammatory program; however, the contribution of SUCNR1 to macrophage phenotype and function has remained unclear. Here we found that activation of SUCNR1 had a critical role in the anti-inflammatory responses in macrophages. Myeloid-specific deficiency in SUCNR1 promoted a local pro-inflammatory phenotype, disrupted glucose homeostasis in mice fed a normal chow diet, exacerbated the metabolic consequences of diet-induced obesity and impaired adipose-tissue browning in response to cold exposure. Activation of SUCNR1 promoted an anti-inflammatory phenotype in macrophages and boosted the response of these cells to type 2 cytokines, including interleukin-4. Succinate decreased the expression of inflammatory markers in adipose tissue from lean human subjects but not that from obese subjects, who had lower expression of SUCNR1 in adipose-tissue-resident macrophages. Our findings highlight the importance of succinate-SUCNR1 signaling in determining macrophage polarization and assign a role to succinate in limiting inflammation.
Assuntos
Inflamação/imunologia , Macrófagos/imunologia , Obesidade/imunologia , Receptores Acoplados a Proteínas G/imunologia , Tecido Adiposo/efeitos dos fármacos , Tecido Adiposo/imunologia , Tecido Adiposo/metabolismo , Animais , Células Cultivadas , Citocinas/genética , Citocinas/imunologia , Citocinas/metabolismo , Perfilação da Expressão Gênica/métodos , Humanos , Inflamação/genética , Inflamação/metabolismo , Macrófagos/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Obesidade/genética , Obesidade/metabolismo , Receptores Acoplados a Proteínas G/deficiência , Receptores Acoplados a Proteínas G/genética , Ácido Succínico/imunologia , Ácido Succínico/metabolismo , Ácido Succínico/farmacologia , Células THP-1RESUMO
Activated macrophages undergo metabolic reprogramming, which drives their pro-inflammatory phenotype, but the mechanistic basis for this remains obscure. Here, we demonstrate that upon lipopolysaccharide (LPS) stimulation, macrophages shift from producing ATP by oxidative phosphorylation to glycolysis while also increasing succinate levels. We show that increased mitochondrial oxidation of succinate via succinate dehydrogenase (SDH) and an elevation of mitochondrial membrane potential combine to drive mitochondrial reactive oxygen species (ROS) production. RNA sequencing reveals that this combination induces a pro-inflammatory gene expression profile, while an inhibitor of succinate oxidation, dimethyl malonate (DMM), promotes an anti-inflammatory outcome. Blocking ROS production with rotenone by uncoupling mitochondria or by expressing the alternative oxidase (AOX) inhibits this inflammatory phenotype, with AOX protecting mice from LPS lethality. The metabolic alterations that occur upon activation of macrophages therefore repurpose mitochondria from ATP synthesis to ROS production in order to promote a pro-inflammatory state.
Assuntos
Inflamação/imunologia , Ativação de Macrófagos , Macrófagos/imunologia , Mitocôndrias/enzimologia , Succinato Desidrogenase/metabolismo , Ácido Succínico/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Carbonil Cianeto m-Clorofenil Hidrazona/farmacologia , Ciclo do Ácido Cítrico , Glicólise , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Inflamação/genética , Interleucina-10/metabolismo , Lipopolissacarídeos/imunologia , Macrófagos/metabolismo , Malonatos/farmacologia , Potencial da Membrana Mitocondrial , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/efeitos dos fármacos , Proteínas Mitocondriais/metabolismo , Oxirredução/efeitos dos fármacos , Fosforilação Oxidativa/efeitos dos fármacos , Oxirredutases/metabolismo , Proteínas de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Análise de Sequência de RNA , Succinato Desidrogenase/genética , TranscriptomaRESUMO
Glutamine metabolism provides synergistic support for macrophage activation and elicitation of desirable immune responses; however, the underlying mechanisms regulated by glutamine metabolism to orchestrate macrophage activation remain unclear. Here we show that the production of α-ketoglutarate (αKG) via glutaminolysis is important for alternative (M2) activation of macrophages, including engagement of fatty acid oxidation (FAO) and Jmjd3-dependent epigenetic reprogramming of M2 genes. This M2-promoting mechanism is further modulated by a high αKG/succinate ratio, whereas a low ratio strengthens the proinflammatory phenotype in classically activated (M1) macrophages. As such, αKG contributes to endotoxin tolerance after M1 activation. This study reveals new mechanistic regulations by which glutamine metabolism tailors the immune responses of macrophages through metabolic and epigenetic reprogramming.
Assuntos
Reprogramação Celular/imunologia , Epigênese Genética , Ácidos Cetoglutáricos/imunologia , Ativação de Macrófagos/imunologia , Macrófagos/imunologia , Animais , Imunoprecipitação da Cromatina , Ciclo do Ácido Cítrico/imunologia , Ácidos Graxos/metabolismo , Perfilação da Expressão Gênica , Glutamina/metabolismo , Glicólise/imunologia , Ácidos Cetoglutáricos/metabolismo , Lipopolissacarídeos , Macrófagos/metabolismo , Metabolômica , Camundongos , NF-kappa B/imunologia , Oxirredução , Fosforilação Oxidativa , Fenótipo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de RNA , Ácido Succínico/metabolismoRESUMO
Glutaminase regulates glutaminolysis to promote cancer cell proliferation. However, the mechanism underlying glutaminase activity regulation is largely unknown. Here, we demonstrate that kidney-type glutaminase (GLS) is highly expressed in human pancreatic ductal adenocarcinoma (PDAC) specimens with correspondingly upregulated glutamine dependence for PDAC cell proliferation. Upon oxidative stress, the succinyl-coenzyme A (CoA) synthetase ADP-forming subunit ß (SUCLA2) phosphorylated by p38 mitogen-activated protein kinase (MAPK) at S79 dissociates from GLS, resulting in enhanced GLS K311 succinylation, oligomerization, and activity. Activated GLS increases glutaminolysis and the production of nicotinamide adenine dinucleotide phosphate (NADPH) and glutathione, thereby counteracting oxidative stress and promoting tumor cell survival and tumor growth in mice. In addition, the levels of SUCLA2 pS79 and GLS K311 succinylation, which were mutually correlated, were positively associated with advanced stages of PDAC and poor prognosis for patients. Our findings reveal critical regulation of GLS by SUCLA2-coupled GLS succinylation regulation and underscore the regulatory role of metabolites in glutaminolysis and PDAC development.
Assuntos
Carcinoma Ductal Pancreático/genética , Glutaminase/genética , Neoplasias Pancreáticas/genética , Succinato-CoA Ligases/genética , Animais , Carcinoma Ductal Pancreático/diagnóstico , Carcinoma Ductal Pancreático/enzimologia , Carcinoma Ductal Pancreático/mortalidade , Linhagem Celular Tumoral , Proliferação de Células , Regulação Neoplásica da Expressão Gênica , Glutaminase/metabolismo , Glutamina/metabolismo , Glutationa/metabolismo , Xenoenxertos , Humanos , Masculino , Camundongos , Camundongos Nus , NADP/metabolismo , Estresse Oxidativo , Neoplasias Pancreáticas/diagnóstico , Neoplasias Pancreáticas/enzimologia , Neoplasias Pancreáticas/mortalidade , Fosforilação , Prognóstico , Processamento de Proteína Pós-Traducional , Transdução de Sinais , Succinato-CoA Ligases/metabolismo , Ácido Succínico/metabolismo , Análise de Sobrevida , Proteínas Quinases p38 Ativadas por Mitógeno/genética , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
Macrophages form a major cell population in the tumor microenvironment. They can be activated and polarized into tumor-associated macrophages (TAM) by the tumor-derived soluble molecules to promote tumor progression and metastasis. Here, we used comparative metabolomics coupled with biochemical and animal studies to show that cancer cells release succinate into their microenvironment and activate succinate receptor (SUCNR1) signaling to polarize macrophages into TAM. Furthermore, the results from in vitro and in vivo studies revealed that succinate promotes not only cancer cell migration and invasion but also cancer metastasis. These effects are mediated by SUCNR1-triggered PI3K-hypoxia-inducible factor 1α (HIF-1α) axis. Compared with healthy subjects and tumor-free lung tissues, serum succinate levels and lung cancer SUCNR1 expression were elevated in lung cancer patients, suggesting an important clinical relevance. Collectively, our findings indicate that the secreted tumor-derived succinate belongs to a novel class of cancer progression factors, controlling TAM polarization and promoting tumorigenic signaling.
Assuntos
Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Macrófagos/metabolismo , Metástase Neoplásica/patologia , Receptores Acoplados a Proteínas G/metabolismo , Ácido Succínico/metabolismo , Células A549 , Animais , Linhagem Celular Tumoral , Movimento Celular/fisiologia , Células HT29 , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Células MCF-7 , Macrófagos/patologia , Camundongos Endogâmicos C57BL , Células PC-3 , Transdução de Sinais/fisiologia , Microambiente Tumoral/fisiologiaRESUMO
Metabolites have functions in the immune system independent of their conventional roles as sources or intermediates in biosynthesis and bioenergetics. We are still in the pioneering phase of gathering information about the functions of specific metabolites in immunoregulation. In this review, we cover succinate, itaconate, α-ketoglutarate, and lactate as examples. Each of these metabolites has a different story of how their immunoregulatory functions were discovered and how their roles in the complex process of inflammation were revealed. Parallels and interactions are emerging between metabolites and cytokines, well-known immunoregulators. We depict molecular mechanisms by which metabolites prime cellular and often physiological changes focusing on intra- and extra-cellular activities and signaling pathways. Possible therapeutic opportunities for immune and inflammatory diseases are emerging.
Assuntos
Ácidos Carboxílicos/imunologia , Ácidos Carboxílicos/metabolismo , Imunidade/imunologia , Animais , Ciclo do Ácido Cítrico , Citocinas/metabolismo , Metabolismo Energético , Humanos , Imunidade/fisiologia , Inflamação/metabolismo , Ácidos Cetoglutáricos/imunologia , Ácidos Cetoglutáricos/metabolismo , Ácido Láctico/imunologia , Ácido Láctico/metabolismo , Transdução de Sinais , Succinatos/imunologia , Succinatos/metabolismo , Ácido Succínico/imunologia , Ácido Succínico/metabolismoRESUMO
The enzymes of the mitochondrial electron transport chain are key players of cell metabolism. Despite being active when isolated, in vivo they associate into supercomplexes1, whose precise role is debated. Supercomplexes CIII2CIV1-2 (refs. 2,3), CICIII2 (ref. 4) and CICIII2CIV (respirasome)5-10 exist in mammals, but in contrast to CICIII2 and the respirasome, to date the only known eukaryotic structures of CIII2CIV1-2 come from Saccharomyces cerevisiae11,12 and plants13, which have different organization. Here we present the first, to our knowledge, structures of mammalian (mouse and ovine) CIII2CIV and its assembly intermediates, in different conformations. We describe the assembly of CIII2CIV from the CIII2 precursor to the final CIII2CIV conformation, driven by the insertion of the N terminus of the assembly factor SCAF1 (ref. 14) deep into CIII2, while its C terminus is integrated into CIV. Our structures (which include CICIII2 and the respirasome) also confirm that SCAF1 is exclusively required for the assembly of CIII2CIV and has no role in the assembly of the respirasome. We show that CIII2 is asymmetric due to the presence of only one copy of subunit 9, which straddles both monomers and prevents the attachment of a second copy of SCAF1 to CIII2, explaining the presence of one copy of CIV in CIII2CIV in mammals. Finally, we show that CIII2 and CIV gain catalytic advantage when assembled into the supercomplex and propose a role for CIII2CIV in fine tuning the efficiency of electron transfer in the electron transport chain.
Assuntos
Respiração Celular , Mitocôndrias/enzimologia , Complexos Multienzimáticos/química , Complexos Multienzimáticos/metabolismo , Ovinos , Animais , Sítios de Ligação , Conjuntos de Dados como Assunto , Transporte de Elétrons , Camundongos , Mitocôndrias/metabolismo , Modelos Moleculares , NAD/metabolismo , Ácido Succínico/metabolismoRESUMO
Brown adipose tissue (BAT) is rich in mitochondria and plays important roles in energy expenditure, thermogenesis, and glucose homeostasis. We find that levels of mitochondrial protein succinylation and malonylation are high in BAT and subject to physiological and genetic regulation. BAT-specific deletion of Sirt5, a mitochondrial desuccinylase and demalonylase, results in dramatic increases in global protein succinylation and malonylation. Mass spectrometry-based quantification of succinylation reveals that Sirt5 regulates the key thermogenic protein in BAT, UCP1. Mutation of the two succinylated lysines in UCP1 to acyl-mimetic glutamine and glutamic acid significantly decreases its stability and activity. The reduced function of UCP1 and other proteins in Sirt5KO BAT results in impaired mitochondria respiration, defective mitophagy, and metabolic inflexibility. Thus, succinylation of UCP1 and other mitochondrial proteins plays an important role in BAT and in regulation of energy homeostasis.
Assuntos
Metabolismo Energético/genética , Mitocôndrias/metabolismo , Obesidade/genética , Sirtuínas/genética , Proteína Desacopladora 1/genética , Tecido Adiposo Marrom/metabolismo , Tecido Adiposo Marrom/patologia , Animais , Regulação da Expressão Gênica , Glucose/metabolismo , Camundongos , Camundongos Knockout , Mitocôndrias/genética , Proteínas Mitocondriais/genética , Obesidade/metabolismo , Obesidade/patologia , Proteômica/métodos , Ácido Succínico/metabolismo , Termogênese/genética , Proteína Desacopladora 1/metabolismoRESUMO
Succinate is a potent immune signalling molecule that is present in the mammalian gut and within macrophages. Both of these infection niches are colonised by the pathogenic bacterium Salmonella enterica serovar Typhimurium during infection. Succinate is a C4-dicarboyxlate that can serve as a source of carbon for bacteria. When succinate is provided as the sole carbon source for in vitro cultivation, Salmonella and other enteric bacteria exhibit a slow growth rate and a long lag phase. This growth inhibition phenomenon was known to involve the sigma factor RpoS, but the genetic basis of the repression of bacterial succinate utilisation was poorly understood. Here, we use an experimental evolution approach to isolate fast-growing mutants during growth of S. Typhimurium on succinate containing minimal medium. Our approach reveals novel RpoS-independent systems that inhibit succinate utilisation. The CspC RNA binding protein restricts succinate utilisation, an inhibition that is antagonised by high levels of the small regulatory RNA (sRNA) OxyS. We discovered that the Fe-S cluster regulatory protein IscR inhibits succinate utilisation by repressing the C4-dicarboyxlate transporter DctA. Furthermore, the ribose operon repressor RbsR is required for the complete RpoS-driven repression of succinate utilisation, suggesting a novel mechanism of RpoS regulation. Our discoveries shed light on the redundant regulatory systems that tightly regulate the utilisation of succinate. We speculate that the control of central carbon metabolism by multiple regulatory systems in Salmonella governs the infection niche-specific utilisation of succinate.
Assuntos
Proteínas de Bactérias , Ácido Succínico , Animais , Proteínas de Bactérias/metabolismo , Ácido Succínico/metabolismo , Salmonella typhimurium/genética , Succinatos/metabolismo , Carbono/metabolismo , Fator sigma/genética , Fator sigma/metabolismo , Regulação Bacteriana da Expressão Gênica , Mamíferos/metabolismoRESUMO
Influenza virus infection causes considerable morbidity and mortality, but current therapies have limited efficacy. We hypothesized that investigating the metabolic signaling during infection may help to design innovative antiviral approaches. Using bronchoalveolar lavages of infected mice, we here demonstrate that influenza virus induces a major reprogramming of lung metabolism. We focused on mitochondria-derived succinate that accumulated both in the respiratory fluids of virus-challenged mice and of patients with influenza pneumonia. Notably, succinate displays a potent antiviral activity in vitro as it inhibits the multiplication of influenza A/H1N1 and A/H3N2 strains and strongly decreases virus-triggered metabolic perturbations and inflammatory responses. Moreover, mice receiving succinate intranasally showed reduced viral loads in lungs and increased survival compared to control animals. The antiviral mechanism involves a succinate-dependent posttranslational modification, that is, succinylation, of the viral nucleoprotein at the highly conserved K87 residue. Succinylation of viral nucleoprotein altered its electrostatic interactions with viral RNA and further impaired the trafficking of viral ribonucleoprotein complexes. The finding that succinate efficiently disrupts the influenza replication cycle opens up new avenues for improved treatment of influenza pneumonia.
Assuntos
Vírus da Influenza A Subtipo H1N1 , Influenza Humana , Infecções por Orthomyxoviridae , Pneumonia , Animais , Antivirais/farmacologia , Humanos , Vírus da Influenza A Subtipo H3N2/metabolismo , Camundongos , Proteínas do Nucleocapsídeo , Nucleoproteínas/metabolismo , Ácido Succínico/metabolismo , Ácido Succínico/farmacologia , Ácido Succínico/uso terapêutico , Replicação ViralRESUMO
Inhalation of crystalline silica dust induces incurable lung damage, silicosis, and pulmonary fibrosis. However, the mechanisms of the lung injury remain poorly understood, with limited therapeutic options aside from lung transplantation. Posttranslational modifications can regulate the function of proteins and play an important role in studying disease mechanisms. To investigate changes in posttranslational modifications of proteins in silicosis, combined quantitative proteome, acetylome, and succinylome analyses were performed with lung tissues from silica-injured and healthy mice using liquid chromatography-mass spectrometry. Combined analysis was applied to the three omics datasets to construct a protein landscape. The acetylation and succinylation of the key transcription factor STAT1 were found to play important roles in the silica-induced pathophysiological changes. Modulating the acetylation level of STAT1 with geranylgeranylacetone effectively inhibited the progression of silicosis. This report revealed a comprehensive landscape of posttranslational modifications in silica-injured mouse and presented a novel therapeutic strategy targeting the posttranslational level for silica-induced lung diseases.
Assuntos
Lisina , Processamento de Proteína Pós-Traducional , Proteoma , Fator de Transcrição STAT1 , Silicose , Animais , Silicose/metabolismo , Silicose/tratamento farmacológico , Silicose/patologia , Fator de Transcrição STAT1/metabolismo , Proteoma/metabolismo , Lisina/metabolismo , Acetilação/efeitos dos fármacos , Camundongos , Dióxido de Silício , Pulmão/metabolismo , Pulmão/efeitos dos fármacos , Pulmão/patologia , Camundongos Endogâmicos C57BL , Proteômica/métodos , Masculino , Ácido Succínico/metabolismoRESUMO
Succinate produced by the commensal protist Tritrichomonas musculis (T. mu) stimulates chemosensory tuft cells, resulting in intestinal type 2 immunity. Tuft cells express the succinate receptor SUCNR1, yet this receptor does not mediate antihelminth immunity nor alter protist colonization. Here, we report that microbial-derived succinate increases Paneth cell numbers and profoundly alters the antimicrobial peptide (AMP) landscape in the small intestine. Succinate was sufficient to drive this epithelial remodeling, but not in mice lacking tuft cell chemosensory components required to detect this metabolite. Tuft cells respond to succinate by stimulating type 2 immunity, leading to interleukin-13-mediated epithelial and AMP expression changes. Moreover, type 2 immunity decreases the total number of mucosa-associated bacteria and alters the small intestinal microbiota composition. Finally, tuft cells can detect short-term bacterial dysbiosis that leads to a spike in luminal succinate levels and modulate AMP production in response. These findings demonstrate that a single metabolite produced by commensals can markedly shift the intestinal AMP profile and suggest that tuft cells utilize SUCNR1 and succinate sensing to modulate bacterial homeostasis.
Assuntos
Anti-Infecciosos , Mucosa Intestinal , Camundongos , Animais , Mucosa Intestinal/metabolismo , Intestino Delgado/metabolismo , Intestinos , Ácido Succínico/metabolismo , Anti-Infecciosos/metabolismoRESUMO
The prevailing notion that reduced cofactors NADH and FADH2 transfer electrons from the tricarboxylic acid cycle to the mitochondrial electron transfer system creates ambiguities regarding respiratory Complex II (CII). CII is the only membrane-bound enzyme in the tricarboxylic acid cycle and is part of the electron transfer system of the mitochondrial inner membrane feeding electrons into the coenzyme Q-junction. The succinate dehydrogenase subunit SDHA of CII oxidizes succinate and reduces the covalently bound prosthetic group FAD to FADH2 in the canonical forward tricarboxylic acid cycle. However, several graphical representations of the electron transfer system depict FADH2 in the mitochondrial matrix as a substrate to be oxidized by CII. This leads to the false conclusion that FADH2 from the ß-oxidation cycle in fatty acid oxidation feeds electrons into CII. In reality, dehydrogenases of fatty acid oxidation channel electrons to the Q-junction but not through CII. The ambiguities surrounding Complex II in the literature and educational resources call for quality control, to secure scientific standards in current communications of bioenergetics, and ultimately support adequate clinical applications. This review aims to raise awareness of the inherent ambiguity crisis, complementing efforts to address the well-acknowledged issues of credibility and reproducibility.
Assuntos
Complexo II de Transporte de Elétrons , Elétrons , Ácidos Graxos , Flavina-Adenina Dinucleotídeo , Succinato Desidrogenase , Transporte de Elétrons , Ácidos Graxos/química , Ácidos Graxos/metabolismo , Flavina-Adenina Dinucleotídeo/análogos & derivados , Flavina-Adenina Dinucleotídeo/metabolismo , Oxirredução , Reprodutibilidade dos Testes , Succinato Desidrogenase/metabolismo , Ciclo do Ácido Cítrico , Mitocôndrias/metabolismo , Ubiquinona/metabolismo , Ácido Succínico/metabolismo , Complexo II de Transporte de Elétrons/metabolismo , Metabolismo EnergéticoRESUMO
The tricarboxylic acid cycle intermediate succinate is involved in metabolic processes and plays a crucial role in the homeostasis of mitochondrial reactive oxygen species1. The receptor responsible for succinate signalling, SUCNR1 (also known as GPR91), is a member of the G-protein-coupled-receptor family2 and links succinate signalling to renin-induced hypertension, retinal angiogenesis and inflammation3-5. Because SUCNR1 senses succinate as an immunological danger signal6-which has relevance for diseases including ulcerative colitis, liver fibrosis7, diabetes and rheumatoid arthritis3,8-it is of interest as a therapeutic target. Here we report the high-resolution crystal structure of rat SUCNR1 in complex with an intracellular binding nanobody in the inactive conformation. Structure-based mutagenesis and radioligand-binding studies, in conjunction with molecular modelling, identified key residues for species-selective antagonist binding and enabled the determination of the high-resolution crystal structure of a humanized rat SUCNR1 in complex with a high-affinity, human-selective antagonist denoted NF-56-EJ40. We anticipate that these structural insights into the architecture of the succinate receptor and its antagonist selectivity will enable structure-based drug discovery and will further help to elucidate the function of SUCNR1 in vitro and in vivo.