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BACKGROUND: The mTOR (mechanistic target of rapamycin) pathway is a complex signaling cascade that regulates cellular growth, proliferation, metabolism, and survival. Although activation of mTOR signaling has been linked to atherosclerosis, its direct role in lesion progression and in plaque macrophages remains poorly understood. We previously demonstrated that mTORC1 (mTOR complex 1) activation promotes atherogenesis through inhibition of autophagy and increased apoptosis in macrophages. METHODS: Using macrophage-specific Rictor- and mTOR-deficient mice, we now dissect the distinct functions of mTORC2 pathways in atherogenesis. RESULTS: In contrast to the atheroprotective effect seen with blockade of macrophage mTORC1, macrophage-specific mTORC2-deficient mice exhibit an atherogenic phenotype, with larger, more complex lesions and increased cell death. In cultured macrophages, we show that mTORC2 signaling inhibits the FoxO1 (forkhead box protein O1) transcription factor, leading to suppression of proinflammatory pathways, especially the inflammasome/IL (interleukin)-1ß response, a key mediator of vascular inflammation and atherosclerosis. In addition, administration of FoxO1 inhibitors efficiently rescued the proinflammatory response caused by mTORC2 deficiency both in vitro and in vivo. Interestingly, collective deletion of macrophage mTOR, which ablates mTORC1- and mTORC2-dependent pathways, leads to minimal change in plaque size or complexity, reflecting the balanced yet opposing roles of these signaling arms. CONCLUSIONS: Our data provide the first mechanistic details of macrophage mTOR signaling in atherosclerosis and suggest that therapeutic measures aimed at modulating mTOR need to account for its dichotomous functions.
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Aterosclerosis , Serina-Treonina Quinasas TOR , Ratones , Animales , Diana Mecanicista del Complejo 2 de la Rapamicina , Serina-Treonina Quinasas TOR/metabolismo , Macrófagos/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Factores de Transcripción/metabolismo , Aterosclerosis/genética , Aterosclerosis/metabolismoRESUMEN
Abnormal gut motility is a feature of several mitochondrial encephalomyopathies, and mutations in genes such as TYMP and POLG, have been linked to these rare diseases. The human genome encodes three DNA ligases, of which only one, ligase III (LIG3), has a mitochondrial splice variant and is crucial for mitochondrial health. We investigated the effect of reduced LIG3 activity and resulting mitochondrial dysfunction in seven patients from three independent families, who showed the common occurrence of gut dysmotility and neurological manifestations reminiscent of mitochondrial neurogastrointestinal encephalomyopathy. DNA from these patients was subjected to whole exome sequencing. In all patients, compound heterozygous variants in a new disease gene, LIG3, were identified. All variants were predicted to have a damaging effect on the protein. The LIG3 gene encodes the only mitochondrial DNA (mtDNA) ligase and therefore plays a pivotal role in mtDNA repair and replication. In vitro assays in patient-derived cells showed a decrease in LIG3 protein levels and ligase activity. We demonstrated that the LIG3 gene defects affect mtDNA maintenance, leading to mtDNA depletion without the accumulation of multiple deletions as observed in other mitochondrial disorders. This mitochondrial dysfunction is likely to cause the phenotypes observed in these patients. The most prominent and consistent clinical signs were severe gut dysmotility and neurological abnormalities, including leukoencephalopathy, epilepsy, migraine, stroke-like episodes, and neurogenic bladder. A decrease in the number of myenteric neurons, and increased fibrosis and elastin levels were the most prominent changes in the gut. Cytochrome c oxidase (COX) deficient fibres in skeletal muscle were also observed. Disruption of lig3 in zebrafish reproduced the brain alterations and impaired gut transit in vivo. In conclusion, we identified variants in the LIG3 gene that result in a mitochondrial disease characterized by predominant gut dysmotility, encephalopathy, and neuromuscular abnormalities.
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ADN Ligasa (ATP)/genética , Enfermedades Gastrointestinales/genética , Motilidad Gastrointestinal/genética , Encefalomiopatías Mitocondriales/genética , Proteínas de Unión a Poli-ADP-Ribosa/genética , Animales , Femenino , Enfermedades Gastrointestinales/patología , Humanos , Masculino , Encefalomiopatías Mitocondriales/patología , Mutación , Linaje , Pez CebraRESUMEN
Browning of adipose tissue is induced by specific stimuli such as cold exposure and consists of up-regulation of thermogenesis in white adipose tissue. Recently, it has emerged as an attractive target for managing obesity in humans. Here, we performed a comprehensive analysis to identify genes associated with browning in murine adipose tissue. We focused on glycerol kinase (GYK) because its mRNA expression pattern is highly correlated with that of uncoupling protein 1 (UCP1), which regulates the thermogenic capacity of adipocytes. Cold exposure-induced Ucp1 up-regulation in inguinal white adipose tissue (iWAT) was partially abolished by Gyk knockdown (KD) in vivo Consistently, the Gyk KD inhibited Ucp1 expression induced by treatment with the ß-adrenergic receptors (ßAR) agonist isoproterenol (Iso) in vitro and resulted in impaired uncoupled respiration. Gyk KD also suppressed Iso- and adenylate cyclase activator-induced transcriptional activation and phosphorylation of the cAMP response element-binding protein (CREB). However, we did not observe these effects with a cAMP analog. Therefore Gyk KD related to Iso-induced cAMP products. In Iso-treated Gyk KD adipocytes, stearoyl-CoA desaturase 1 (SCD1) was up-regulated, and monounsaturated fatty acids such as palmitoleic acid (POA) accumulated. Moreover, a SCD1 inhibitor treatment recovered the Gyk KD-induced Ucp1 down-regulation and POA treatment down-regulated Iso-activated Ucp1 Our findings suggest that Gyk stimulates Ucp1 expression via a mechanism that partially depends on the ßAR-cAMP-CREB pathway and Gyk-mediated regulation of fatty acid metabolism.
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Adipocitos Beige/metabolismo , Frío , Ácidos Grasos/metabolismo , Glicerol Quinasa/metabolismo , Sistemas de Mensajero Secundario , Termogénesis , Activación Transcripcional , Proteína Desacopladora 1/biosíntesis , Adipocitos Beige/citología , Animales , AMP Cíclico/genética , AMP Cíclico/metabolismo , Ácidos Grasos/genética , Glicerol Quinasa/genética , Isoproterenol/farmacología , Masculino , Ratones , Estearoil-CoA Desaturasa/genética , Estearoil-CoA Desaturasa/metabolismo , Proteína Desacopladora 1/genéticaRESUMEN
Specific conditions, such as exposure to cold, can induce the production of brown-like adipocytes in white adipose tissue. These adipocytes express high levels of uncoupling protein 1 (UCP1) and energy expended by generating heat. Thus, these are a potential target for the prevention or treatment of obesity. The present study involved a comprehensive analysis of the adipose tissue to understand the relationship between long non-coding RNA (lncRNA) 2310069B03Rik and UCP1. Cold exposure increased both lncRNA 2310069B03Rik and Ucp1 expression in inguinal white adipose tissue (iWAT). However, overexpression of lncRNA 2310069B03Rik suppressed the Ucp1 mRNA expression and the promoter activity of UCP1 in the iWAT primary adipocytes. In addition, compared to the early induction of Ucp1 expression by cold stimulation, the induction of lncRNA 2310069B03Rik expression was later. These results suggest that lncRNA 2310069B03Rik functions as a suppression factor of Ucp1 expression.
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Frío , ARN Largo no Codificante/metabolismo , Proteína Desacopladora 1/genética , Adipocitos Beige , Agonistas Adrenérgicos beta/farmacología , Animales , Células Cultivadas , Regulación hacia Abajo , Regulación de la Expresión Génica/efectos de los fármacos , Masculino , Ratones , Ratones Endogámicos C57BL , Termogénesis/genética , Proteína Desacopladora 1/metabolismoRESUMEN
Among dietary fatty acids with immunologic effects, ω-3 polyunsaturated fatty acids, such as α-linolenic acid (ALA), have been considered as factors that contribute to the differentiation of M2-type macrophages (M2 macrophages). In this study, we examined the effect of ALA and its gut lactic acid bacteria metabolites 13-hydroxy-9(Z),15(Z)-octadecadienoic acid (13-OH) and 13-oxo-9(Z),15(Z)-octadecadienoic acid (13-oxo) on the differentiation of M2 macrophages from bone marrow-derived cells (BMDCs) and investigated the underlying mechanisms. BMDCs were stimulated with ALA, 13-OH, or 13-oxo in the presence of IL-4 or IL-13 for 24 h, and significant increases in M2 macrophage markers CD206 and Arginase-1 (Arg1) were observed. In addition, M2 macrophage phenotypes were less prevalent following cotreatment with GPCR40 antagonists or inhibitors of PLC-ß and MEK under these conditions, suggesting that GPCR40 signaling is involved in the regulation of M2 macrophage differentiation. In further experiments, remarkable M2 macrophage accumulation was observed in the lamina propria of the small intestine of C57BL/6 mice after intragastric treatments with ALA, 13-OH, or 13-oxo at 1 g/kg of body weight per day for 3 d. These findings suggest a novel mechanism of M2 macrophage differentiation involving fatty acids from gut lactic acid bacteria and GPCR40 signaling.-Ohue-Kitano, R., Yasuoka, Y., Goto, T., Kitamura, N., Park, S.-B., Kishino, S., Kimura, I., Kasubuchi, M., Takahashi, H., Li, Y., Yeh, Y.-S., Jheng, H.-F., Iwase, M., Tanaka, M., Masuda, S., Inoue, T., Yamakage, H., Kusakabe, T., Tani, F., Shimatsu, A., Takahashi, N., Ogawa, J., Satoh-Asahara, N., Kawada, T. α-Linolenic acid-derived metabolites from gut lactic acid bacteria induce differentiation of anti-inflammatory M2 macrophages through G protein-coupled receptor 40.
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Lactobacillales/metabolismo , Macrófagos/citología , Macrófagos/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Ácido alfa-Linolénico/metabolismo , Animales , Diferenciación Celular , Microbioma Gastrointestinal , Células HEK293 , Humanos , Inmunidad Innata , Interleucina-4/metabolismo , Sistema de Señalización de MAP Quinasas , Macrófagos/inmunología , Masculino , Ratones , Ratones Endogámicos C57BL , Modelos Biológicos , PPAR gamma/metabolismoAsunto(s)
Inhibidores de Hidroximetilglutaril-CoA Reductasas , Proproteína Convertasa 9 , Proproteína Convertasa 9/genética , Inhibidores de Hidroximetilglutaril-CoA Reductasas/farmacología , Inhibidores de Hidroximetilglutaril-CoA Reductasas/uso terapéutico , Proproteína Convertasas , Serina EndopeptidasasRESUMEN
Emergence of thermogenic adipocytes such as brown and beige adipocytes is critical for whole body energy metabolism. Promoting the emergence of these adipocytes, which increase energy expenditure, could be a viable strategy in treating obesity and its related diseases. However, little is known regarding the mechanisms that regulate the emergence of these adipocytes in obese adipose tissue. Here, we demonstrated that classically activated macrophages (M1 MÏ) suppress the induction of thermogenic adipocytes in obese adipose tissues of mice. Cold exposure significantly induced the expression levels of uncoupling protein-1 (UCP1), which is a mitochondrial protein unique in thermogenic adipocytes, in C57BL/6 mice fed a normal diet. However, UCP1 induction was significantly suppressed in adipose tissues of C57BL/6 mice fed a high-fat diet, into which M1 MÏ infiltrated. Depletion of M1 MÏ using clodronate liposomes eliminated the suppressive effect and markedly reduced the mRNA level of tumor necrosis factor-α (TNFα) in the adipose tissues. Importantly, consistent with the observed changes in the expression levels of marker genes for thermogenic adipocytes, combination treatment of clodronate liposome and cold exposure resulted in metabolic benefits such as lowered body weight and blood glucose level in obese mice. Moreover, intraperitoneal injection of recombinant TNFα protein suppressed UCP1 induction in lean adipose tissues of mice. Collectively, our data indicate that infiltrated M1 MÏ suppress the induction of thermogenic adipocytes in obese adipose tissues via TNFα. This report suggests that inflammation induced by infiltrated MÏ could cause not only insulin resistance but also reduction of energy expenditure in adipose tissues.
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Tejido Adiposo/metabolismo , Diferenciación Celular/inmunología , Resistencia a la Insulina/inmunología , Macrófagos/inmunología , Obesidad/metabolismo , ARN Mensajero/metabolismo , Factor de Necrosis Tumoral alfa/inmunología , Proteína Desacopladora 1/genética , Adipocitos Beige/efectos de los fármacos , Adipocitos Beige/metabolismo , Adipocitos Marrones/efectos de los fármacos , Adipocitos Marrones/metabolismo , Tejido Adiposo/efectos de los fármacos , Tejido Adiposo/inmunología , Animales , Diferenciación Celular/efectos de los fármacos , Ácido Clodrónico/farmacología , Frío , Dieta Alta en Grasa , Metabolismo Energético/inmunología , Immunoblotting , Inmunohistoquímica , Liposomas , Macrófagos/efectos de los fármacos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Obesos , Obesidad/inmunología , ARN Mensajero/efectos de los fármacos , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Termogénesis , Factor de Necrosis Tumoral alfa/efectos de los fármacos , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/farmacología , Proteína Desacopladora 1/efectos de los fármacos , Proteína Desacopladora 1/metabolismoRESUMEN
Isoprenoids such as geranylgeranyl pyrophosphate (GGPP) influence various biological processes. Here we show that GGPP inhibits adipocyte differentiation via the liver X receptors (LXRs) pathway. Intracellular GGPP levels and GGPP synthase (Ggps) mRNA expression increases during adipocyte differentiation. Ggps expression also increases in white adipose tissue of obese mice. GGPP addition reduces the expression of adipogenic marker genes such as adipocyte fatty acid binding protein, peroxisome proliferator-activated receptor γ, and insulin-stimulated glucose uptake. Similarly, over-expressing Ggps inhibits adipocyte differentiation. In contrast, Ggps knockdown promotes adipocyte differentiation. Inhibition of adipocyte differentiation by GGPP was partially reduced by LXR agonist T0901317. Furthermore, Ggps knockdown up-regulates LXR target genes during adipocyte differentiation. These results suggest that GGPP may act as an endogenous regulator of adipocyte differentiation and maturation through a mechanism partially dependent on the LXR pathway.
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Adipocitos/metabolismo , Receptores X del Hígado/metabolismo , Fosfatos de Poliisoprenilo/farmacología , Transducción de Señal/efectos de los fármacos , Células 3T3-L1 , Adipocitos/citología , Adipocitos/efectos de los fármacos , Animales , Biomarcadores/metabolismo , Diferenciación Celular/efectos de los fármacos , Farnesiltransferasa/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Técnicas de Silenciamiento del Gen , Espacio Intracelular/metabolismo , Metabolismo de los Lípidos/efectos de los fármacos , Receptores X del Hígado/antagonistas & inhibidores , Masculino , Ratones , Ratones Endogámicos C57BL , Complejos Multienzimáticos/metabolismo , Transducción de Señal/genética , Factores de TiempoRESUMEN
High protein intake is common in western societies and is often promoted as part of a healthy lifestyle; however, amino-acid-mediated mammalian target of rapamycin (mTOR) signalling in macrophages has been implicated in the pathogenesis of ischaemic cardiovascular disease. In a series of clinical studies on male and female participants ( NCT03946774 and NCT03994367 ) that involved graded amounts of protein ingestion together with detailed plasma amino acid analysis and human monocyte/macrophage experiments, we identify leucine as the key activator of mTOR signalling in macrophages. We describe a threshold effect of high protein intake and circulating leucine on monocytes/macrophages wherein only protein in excess of â¼25 g per meal induces mTOR activation and functional effects. By designing specific diets modified in protein and leucine content representative of the intake in the general population, we confirm this threshold effect in mouse models and find ingestion of protein in excess of â¼22% of dietary energy requirements drives atherosclerosis in male mice. These data demonstrate a mechanistic basis for the adverse impact of excessive dietary protein on cardiovascular risk.
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Enfermedades Cardiovasculares , Humanos , Masculino , Femenino , Ratones , Animales , Leucina/metabolismo , Leucina/farmacología , Factores de Riesgo , Serina-Treonina Quinasas TOR/metabolismo , Macrófagos/metabolismo , Factores de Riesgo de Enfermedad Cardiaca , Mamíferos/metabolismoRESUMEN
INTRODUCTION: Lipid-laden foam cells within atherosclerotic plaques are key players in all phases of lesion development including its progression, necrotic core formation, fibrous cap thinning, and eventually plaque rupture. Manipulating foam cell biology is thus an attractive therapeutic strategy at early, middle, and even late stages of atherosclerosis. Traditional therapies have focused on prevention, especially lowering plasma lipid levels. Despite these interventions, atherosclerosis remains a major cause of cardiovascular disease, responsible for the largest numbers of death worldwide. AREAS COVERED: Foam cells within atherosclerotic plaques are comprised of macrophages, vascular smooth muscle cells, and other cell types which are exposed to high concentrations of lipoproteins accumulating within the subendothelial intimal layer. Macrophage-derived foam cells are particularly well studied and have provided important insights into lipid metabolism and atherogenesis. The contributions of foam cell-based processes are discussed with an emphasis on areas of therapeutic potential and directions for drug development. EXERT OPINION: As key players in atherosclerosis, foam cells are attractive targets for developing more specific, targeted therapies aimed at resolving atherosclerotic plaques. Recent advances in our understanding of lipid handling within these cells provide insights into how they might be manipulated and clinically translated to better treat atherosclerosis.
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Aterosclerosis , Placa Aterosclerótica , Humanos , Células Espumosas/metabolismo , Células Espumosas/patología , Placa Aterosclerótica/tratamiento farmacológico , Placa Aterosclerótica/patología , Aterosclerosis/tratamiento farmacológico , Macrófagos/metabolismo , LipoproteínasRESUMEN
In the research setting, white adipose tissue (WAT) transplantation, also known as fat transplantation, is often used to understand the physiological function of adipocytes or associated stromal vascular cells such as macrophages in the context of local and systemic metabolism. The mouse is the most common animal model used where WAT from a donor is transferred either to a subcutaneous site of the same organism or to a subcutaneous region of a recipient. Here, we describe in detail the procedure for heterologous fat transplantation, and, given the need for survival surgery, peri- and postoperative care and subsequent histological confirmation of fat grafts will also be discussed.
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Adipocitos , Tejido Adiposo Blanco , Ratones , Animales , Tejido Adiposo Blanco/metabolismo , Adipocitos/metabolismo , Modelos Animales , Tejido Adiposo/irrigación sanguíneaRESUMEN
The high thermogenic activity of brown adipose tissue (BAT) has received considerable attention. Here, we demonstrated the role of the mevalonate (MVA) biosynthesis pathway in the regulation of brown adipocyte development and survival. The inhibition of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), the rate-limiting enzyme in the MVA pathway and the molecular target of statins, suppressed brown adipocyte differentiation by suppressing protein geranylgeranylation-mediated mitotic clonal expansion. The development of BAT in neonatal mice exposed to statins during the fetal period was severely impaired. Moreover, statin-induced geranylgeranyl pyrophosphate (GGPP) deficiency led to the apoptosis of mature brown adipocytes. Brown adipocyte-specific Hmgcr knockout induced BAT atrophy and disrupted thermogenesis. Importantly, both genetic and pharmacological inhibition of HMGCR in adult mice induced morphological changes in BAT accompanied by an increase in apoptosis, and statin-treated diabetic mice showed worsened hyperglycemia. These findings revealed that MVA pathway-generated GGPP is indispensable for BAT development and survival.
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Dysfunction in the macrophage lysosomal system including reduced acidity and diminished degradative capacity is a hallmark of atherosclerosis, leading to blunted clearance of excess cellular debris and lipids in plaques and contributing to lesion progression. Devising strategies to rescue this macrophage lysosomal dysfunction is a novel therapeutic measure. Nanoparticles have emerged as an effective platform to both target specific tissues and serve as drug delivery vehicles. In most cases, administered nanoparticles are taken up non-selectively by the mononuclear phagocyte system including monocytes/macrophages leading to the undesirable degradation of cargo in lysosomes. We took advantage of this default route to target macrophage lysosomes to rectify their acidity in disease states such as atherosclerosis. Herein, we develop and test two commonly used acidic nanoparticles, poly-lactide-co-glycolic acid (PLGA) and polylactic acid (PLA), both in vitro and in vivo. Our results in cultured macrophages indicate that the PLGA-based nanoparticles are the most effective at trafficking to and enhancing acidification of lysosomes. PLGA nanoparticles also provide functional benefits including enhanced lysosomal degradation, promotion of macroautophagy/autophagy and protein aggregate removal, and reduced apoptosis and inflammasome activation. We demonstrate the utility of this system in vivo, showing nanoparticle accumulation in, and lysosomal acidification of, macrophages in atherosclerotic plaques. Long-term administration of PLGA nanoparticles results in significant reductions in surrogates of plaque complexity with reduced apoptosis, necrotic core formation, and cytotoxic protein aggregates and increased fibrous cap formation. Taken together, our data support the use of acidic nanoparticles to rescue macrophage lysosomal dysfunction in the treatment of atherosclerosis.Abbreviations: BCA: brachiocephalic arteries; FACS: fluorescence activated cell sorting; FITC: fluorescein-5-isothiocyanatel; IL1B: interleukin 1 beta; LAMP: lysosomal associated membrane protein; LIPA/LAL: lipase A, lysosomal acid type; LSDs: lysosomal storage disorders; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MFI: mean fluorescence intensity; MPS: mononuclear phagocyte system; PEGHDE: polyethylene glycol hexadecyl ether; PLA: polylactic acid; PLGA: poly-lactide-co-glycolic acid; SQSTM1/p62: sequestosome 1.
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Aterosclerosis , Nanopartículas , Placa Aterosclerótica , Humanos , Autofagia , Aterosclerosis/patología , Macrófagos/metabolismo , Placa Aterosclerótica/patología , Lisosomas/metabolismo , Ácidos/metabolismo , Poliésteres/metabolismoRESUMEN
Previous studies have demonstrated that a high-protein diet leads to increased atherosclerosis in mice, and that this adverse effect is caused by activation of macrophage mTORC1 signaling. Here, we provide a detailed protocol for the evaluation of diet-induced mTORC1 signaling in plaque macrophages in atherosclerosis-prone apolipoprotein E (ApoE) knockout (KO) mice. This protocol includes flow cytometry and immunofluorescence analysis of atherosclerotic macrophages that can be used to study the atherogenic potential of a variety of mTORC1 modulators. For complete details on the use and execution of this protocol, please refer to Zhang et al. (2020).
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Aterosclerosis , Ratones , Animales , Citometría de Flujo , Macrófagos , Ratones Noqueados , Técnica del Anticuerpo FluorescenteRESUMEN
BACKGROUND: Obesity is a state of excess energy storage resulting in body fat accumulation, and postmenopausal obesity is a rising issue. In this study using ovariectomized (OVX) rats, we mimicked low estrogen levels in a postmenopausal state in order to investigate the effects of different amounts and types of dietary fatty acids on body fat accumulation and body lipid metabolism. METHODS: At 9 weeks of age, rats (n = 40) were given an ovariectomy, eight of which were sham-operated to serve as a control group (S). We then divided OVX rats into four different intervention groups: diet with 5% soybean oil (C), and diet with 5% (L), 15% (M), and 20% (H) (w/w) experimental oil, containing 60% monounsaturated fatty acids (MUFAs) and with a polyunsaturated/saturated fatty acid (P/S) ratio of 5. RESULTS: After OVX, compared to the S group, the C group showed significantly higher body weight, and insulin and leptin levels. Compared to the C group, the H group had lower hepatic triglyceride level and FAS enzyme activity, and higher hepatic ACO and CPT-1 gene expressions and enzyme activities. CONCLUSIONS: An OVX leads to severe weight gain and lipid metabolism abnormalities, while according to previous studies, high fat diet may worsen the situation. However, during our experiment, we discovered that the experimental oil mixture with 60% MUFAs and P/S = 5 may ameliorate these imbalances.
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Tejido Adiposo , Grasas Insaturadas en la Dieta/administración & dosificación , Grasas de la Dieta/administración & dosificación , Ácidos Grasos Insaturados/administración & dosificación , Ácidos Grasos/administración & dosificación , Metabolismo de los Lípidos , Animales , Dieta con Restricción de Grasas , Dieta Alta en Grasa , Ácido Graso Sintasas/metabolismo , Ácidos Grasos Monoinsaturados/administración & dosificación , Femenino , Insulina/sangre , Leptina/sangre , Hígado/metabolismo , Ovariectomía , Ratas , Ratas Sprague-Dawley , Aceite de Soja/administración & dosificación , Triglicéridos/metabolismo , Aumento de PesoRESUMEN
The autophagy-lysosome system is an important cellular degradation pathway that recycles dysfunctional organelles and cytotoxic protein aggregates. A decline in this system is pathogenic in many human diseases including neurodegenerative disorders, fatty liver disease, and atherosclerosis. Thus there is intense interest in discovering therapeutics aimed at stimulating the autophagy-lysosome system. Trehalose is a natural disaccharide composed of two glucose molecules linked by a É-1,1-glycosidic bond with the unique ability to induce cellular macroautophagy/autophagy and with reported efficacy on mitigating several diseases where autophagy is dysfunctional. Interestingly, the mechanism by which trehalose induces autophagy is unknown. One suggested mechanism is its ability to activate TFEB (transcription factor EB), the master transcriptional regulator of autophagy-lysosomal biogenesis. Here we describe a potential mechanism involving direct trehalose action on the lysosome. We find trehalose is endocytically taken up by cells and accumulates within the endolysosomal system. This leads to a low-grade lysosomal stress with mild elevation of lysosomal pH, which acts as a potent stimulus for TFEB activation and nuclear translocation. This process appears to involve inactivation of MTORC1, a known negative regulator of TFEB which is sensitive to perturbations in lysosomal pH. Taken together, our data show the trehalose can act as a weak inhibitor of the lysosome which serves as a trigger for TFEB activation. Our work not only sheds light on trehalose action but suggests that mild alternation of lysosomal pH can be a novel method of inducing the autophagy-lysosome system.Abbreviations: ASO: antisense oligonucleotide; AU: arbitrary units; BMDM: bone marrow-derived macrophages; CLFs: crude lysosomal fractions; CTSD: cathepsin D; LAMP: lysosomal associated membrane protein; LIPA/LAL: lipase A, lysosomal acid type; MAP1LC3: microtubule-associated protein 1 light chain 3; MFI: mean fluorescence intensity; MTORC1: mechanistic target of rapamycin kinase complex 1; pMAC: peritoneal macrophages; SLC2A8/GLUT8: solute carrier family 2, (facilitated glucose transporter), member 8; TFEB: transcription factor EB; TMR: tetramethylrhodamine; TREH: trehalase.
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Autofagia , Factores de Transcripción Básicos con Cremalleras de Leucinas y Motivos Hélice-Asa-Hélice/metabolismo , Lisosomas/metabolismo , Trehalosa/metabolismo , Animales , Autofagia/fisiología , Factores de Transcripción Básicos con Cremalleras de Leucinas y Motivos Hélice-Asa-Hélice/fisiología , Western Blotting , Endocitosis , Técnica del Anticuerpo Fluorescente , Cromatografía de Gases y Espectrometría de Masas , Lisosomas/fisiología , Macrófagos Peritoneales/metabolismo , Macrófagos Peritoneales/fisiología , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Ratones , Trehalosa/fisiologíaRESUMEN
An efficient organocatalytic quadruple cascade reaction resulting in spiroxindole scaffolds bearing five quaternary stereocenters is reported. The complex cascade reaction is triggered by the scarcely explored vinylogous Michael addition of 3-alkylidene oxindoles to fully substituted enones and demonstrates the usefulness of the latter as efficient Michael acceptors in generating complex caged products in 26-92% yields, 14-98% ee and up to >25 : 1 d.r. values.
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The mevalonate pathway is essential for the synthesis of isoprenoids and cholesterol. Adipose tissue is known as a major site for cholesterol storage; however, the role of the local mevalonate pathway and its synthesized isoprenoids remains unclear. In this study, adipose-specific mevalonate pathway-disrupted (aKO) mice were generated through knockout of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase (HMGCR). aKO mice showed serious lipodystrophy accompanied with glucose and lipid metabolic disorders and hepatomegaly. These metabolic variations in aKO mice were dramatically reversed after fat transplantation. In addition, HMGCR-disrupted adipocytes exhibited loss of lipid accumulation and an increase of cell death, which were ameliorated by the supplementation of mevalonate and geranylgeranyl pyrophosphate but not farnesyl pyrophosphate and squalene. Finally, we found that apoptosis may be involved in adipocyte death induced by HMGCR down-regulation. Our findings indicate that the mevalonate pathway is essential for adipocytes and further suggest that this pathway is an important regulator of adipocyte turnover.
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To clarify the effects of a dipeptidyl peptidase-4 (DPP-4) inhibitor on whole-body energy metabolism, we treated mice fed a high-fat diet (HFD) with teneligliptin, a clinically available DPP-4 inhibitor. Teneligliptin significantly prevented HFD-induced obesity and obesity-associated metabolic disorders. It also increased oxygen consumption rate and upregulated uncoupling protein 1 (UCP1) expression in both brown adipose tissue (BAT) and inguinal white adipose tissue (iWAT), suggesting that it enhances BAT function. Soluble DPP-4 inhibited ß-adrenoreceptor-stimulated UCP1 expression in primary adipocytes, and this inhibition was prevented in the presence of teneligliptin, or an extracellular signal-related kinase inhibitor. These results indicate that soluble DPP-4 inhibits ß-adrenoreceptor-stimulated UCP1 induction and that chronic DPP-4 inhibitor treatment may prevent obesity through the activation of BAT function.