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1.
Cell ; 171(5): 1094-1109.e15, 2017 Nov 16.
Artículo en Inglés | MEDLINE | ID: mdl-29149604

RESUMEN

Cholesterol is a critical nutrient requiring tight constraint in the endoplasmic reticulum (ER) due to its uniquely challenging biophysical properties. While the mechanisms by which the ER defends against cholesterol insufficiency are well described, it remains unclear how the ER senses and effectively defends against cholesterol excess. Here, we identify the ER-bound transcription factor nuclear factor erythroid 2 related factor-1, Nrf1/Nfe2L1, as a critical mediator of this process. We show that Nrf1 directly binds to and specifically senses cholesterol in the ER through a defined domain and that cholesterol regulates Nrf1 turnover, processing, localization, and activity. In Nrf1 deficiency, in vivo cholesterol challenges induce massive hepatic cholesterol accumulation and damage, which is rescued by replacing Nrf1 exogenously. This Nrf1-mediated mechanism involves the suppression of CD36-driven inflammatory signaling and derepression of liver X receptor activity. These findings reveal Nrf1 as a guardian of cholesterol homeostasis and a core component of adaptive responses to excess cellular cholesterol.


Asunto(s)
Colesterol/metabolismo , Retículo Endoplásmico/metabolismo , Hígado/metabolismo , Factor Nuclear 1 de Respiración/metabolismo , Animales , Antígenos CD36/metabolismo , Hígado Graso/metabolismo , Regulación de la Expresión Génica , Homeostasis , Humanos , Hígado/citología , Ratones , Transcripción Genética
2.
EMBO J ; 43(2): 168-195, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38212382

RESUMEN

Coenzyme Q (CoQ) is essential for mitochondrial respiration and required for thermogenic activity in brown adipose tissues (BAT). CoQ deficiency leads to a wide range of pathological manifestations, but mechanistic consequences of CoQ deficiency in specific tissues, such as BAT, remain poorly understood. Here, we show that pharmacological or genetic CoQ deficiency in BAT leads to stress signals causing accumulation of cytosolic mitochondrial RNAs and activation of the eIF2α kinase PKR, resulting in activation of the integrated stress response (ISR) with suppression of UCP1 but induction of FGF21 expression. Strikingly, despite diminished UCP1 levels, BAT CoQ deficiency displays increased whole-body metabolic rates at room temperature and thermoneutrality resulting in decreased weight gain on high-fat diets (HFD). In line with enhanced metabolic rates, BAT and inguinal white adipose tissue (iWAT) interorgan crosstalk caused increased browning of iWAT in BAT-specific CoQ deficient animals. This mitohormesis-like effect depends on the ATF4-FGF21 axis and BAT-secreted FGF21, revealing an unexpected role for CoQ in the modulation of whole-body energy expenditure with wide-ranging implications for primary and secondary CoQ deficiencies.


Asunto(s)
Tejido Adiposo Pardo , Ataxia , Factores de Crecimiento de Fibroblastos , Enfermedades Mitocondriales , Debilidad Muscular , Animales , Ratones , Tejido Adiposo Pardo/metabolismo , Ubiquinona/metabolismo , Ubiquinona/farmacología , Enfermedades Mitocondriales/metabolismo , Termogénesis/genética , Ratones Endogámicos C57BL
3.
Nature ; 603(7902): 736-742, 2022 03.
Artículo en Inglés | MEDLINE | ID: mdl-35264794

RESUMEN

Cells display complex intracellular organization by compartmentalization of metabolic processes into organelles, yet the resolution of these structures in the native tissue context and their functional consequences are not well understood. Here we resolved the three-dimensional structural organization of organelles in large (more than 2.8 × 105 µm3) volumes of intact liver tissue (15 partial or full hepatocytes per condition) at high resolution (8 nm isotropic pixel size) using enhanced focused ion beam scanning electron microscopy1,2 imaging followed by deep-learning-based automated image segmentation and 3D reconstruction. We also performed a comparative analysis of subcellular structures in liver tissue of lean and obese mice and found substantial alterations, particularly in hepatic endoplasmic reticulum (ER), which undergoes massive structural reorganization characterized by marked disorganization of stacks of ER sheets3 and predominance of ER tubules. Finally, we demonstrated the functional importance of these structural changes by monitoring the effects of experimental recovery of the subcellular organization on cellular and systemic metabolism. We conclude that the hepatic subcellular organization of the ER architecture are highly dynamic, integrated with the metabolic state and critical for adaptive homeostasis and tissue health.


Asunto(s)
Retículo Endoplásmico , Homeostasis , Hígado , Animales , Retículo Endoplásmico/metabolismo , Hígado/citología , Ratones , Microscopía/métodos , Orgánulos
4.
Biochim Biophys Acta Mol Cell Biol Lipids ; 1869(6): 159512, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38761895

RESUMEN

OBJECTIVE: Excess cholesterol storage can induce the formation of cholesterol crystals in hepatocyte lipid droplets. Such crystals distinguish metabolic dysfunction associated steatohepatitis (MASH) from simple steatosis and may underlie its pathogenesis by causing cell damage that triggers liver inflammation. The mechanism linking cholesterol excess to its crystallization in lipid droplets is unclear. As cholesteryl esters localize to and accumulate in lipid droplets more readily than unesterified free cholesterol, we investigated whether cholesterol esterification by sterol O-acyltransferase (SOAT), also known as acyl co-A cholesterol acyltransferase (ACAT), is required for hepatocyte lipid droplet crystal formation. METHOD: Cholesterol crystals were measured in cholesterol loaded Hep3B hepatocytes, RAW264.7 macrophages, and mouse liver using polarizing light microscopy. We examined the effect of blocking SOAT activity on crystal formation and compared these results to features of cholesterol metabolism and the progression to intracellular crystal deposits. RESULTS: Cholesterol loading of Hep3B cells caused robust levels of lipid droplet localized crystal formation in a dose- and time-dependent manner. Co-treatment with SOAT inhibitors and genetic ablation of SOAT1 blocked crystal formation. SOAT inhibitor also blocked crystal formation in low density lipoprotein (LDL) treated Hep3B cells, acetylated LDL treated RAW 264.7 macrophages, and in the liver of mice genetically predisposed to hepatic cholesterol overload and in mice with cholesterol enriched diet-induced MASH. CONCLUSION: SOAT1-mediated esterification may underlie cholesterol crystals associated with MASH by concentrating it in lipid droplets. These findings imply that inhibiting hepatocyte SOAT1 may be able to alleviate cholesterol associated MASH. Moreover, that either a lipid droplet localized cholesteryl ester hydrolase is required for cholesterol crystal formation, or the crystals are composed of cholesteryl ester.


Asunto(s)
Colesterol , Hepatocitos , Gotas Lipídicas , Esterol O-Aciltransferasa , Animales , Humanos , Masculino , Ratones , Colesterol/metabolismo , Ésteres del Colesterol/metabolismo , Cristalización , Esterificación , Hepatocitos/metabolismo , Gotas Lipídicas/metabolismo , Hígado/metabolismo , Hígado/patología , Ratones Endogámicos C57BL , Células RAW 264.7 , Esterol O-Aciltransferasa/metabolismo , Esterol O-Aciltransferasa/genética
5.
Nat Commun ; 15(1): 3982, 2024 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-38729945

RESUMEN

The hepatocytes within the liver present an immense capacity to adapt to changes in nutrient availability. Here, by using high resolution volume electron microscopy, we map how hepatic subcellular spatial organization is regulated during nutritional fluctuations and as a function of liver zonation. We identify that fasting leads to remodeling of endoplasmic reticulum (ER) architecture in hepatocytes, characterized by the induction of single rough ER sheet around the mitochondria, which becomes larger and flatter. These alterations are enriched in periportal and mid-lobular hepatocytes but not in pericentral hepatocytes. Gain- and loss-of-function in vivo models demonstrate that the Ribosome receptor binding protein1 (RRBP1) is required to enable fasting-induced ER sheet-mitochondria interactions and to regulate hepatic fatty acid oxidation. Endogenous RRBP1 is enriched around periportal and mid-lobular regions of the liver. In obesity, ER-mitochondria interactions are distinct and fasting fails to induce rough ER sheet-mitochondrion interactions. These findings illustrate the importance of a regulated molecular architecture for hepatocyte metabolic flexibility.


Asunto(s)
Retículo Endoplásmico , Ayuno , Hepatocitos , Hígado , Obesidad , Ayuno/metabolismo , Retículo Endoplásmico/metabolismo , Animales , Hepatocitos/metabolismo , Obesidad/metabolismo , Obesidad/patología , Hígado/metabolismo , Ratones , Masculino , Ratones Endogámicos C57BL , Mitocondrias/metabolismo , Mitocondrias Hepáticas/metabolismo , Mitocondrias Hepáticas/ultraestructura , Ácidos Grasos/metabolismo , Humanos , Oxidación-Reducción , Proteínas Ribosómicas/metabolismo
6.
bioRxiv ; 2024 Jun 08.
Artículo en Inglés | MEDLINE | ID: mdl-38895340

RESUMEN

Imbalances in lipid storage and secretion lead to the accumulation of hepatocyte lipid droplets (LDs) (i.e., hepatic steatosis). Our understanding of the mechanisms that govern the channeling of hepatocyte neutral lipids towards cytosolic LDs or secreted lipoproteins remains incomplete. Here, we performed a series of CRISPR-Cas9 screens under different metabolic states to uncover mechanisms of hepatic neutral lipid flux. Clustering of chemical-genetic interactions identified CLIC-like chloride channel 1 (CLCC1) as a critical regulator of neutral lipid storage and secretion. Loss of CLCC1 resulted in the buildup of large LDs in hepatoma cells and knockout in mice caused liver steatosis. Remarkably, the LDs are in the lumen of the ER and exhibit properties of lipoproteins, indicating a profound shift in neutral lipid flux. Finally, remote homology searches identified a domain in CLCC1 that is homologous to yeast Brl1p and Brr6p, factors that promote the fusion of the inner and outer nuclear envelopes during nuclear pore complex assembly. Loss of CLCC1 lead to extensive nuclear membrane herniations, consistent with impaired nuclear pore complex assembly. Thus, we identify CLCC1 as the human Brl1p/Brr6p homolog and propose that CLCC1-mediated membrane remodeling promotes hepatic neutral lipid flux and nuclear pore complex assembly.

7.
Artículo en Inglés | MEDLINE | ID: mdl-35940911

RESUMEN

The endoplasmic reticulum (ER) is a key organelle involved in the regulation of lipid and glucose metabolism, proteostasis, Ca2+ signaling, and detoxification. The structural organization of the ER is very dynamic and complex, with distinct subdomains such as the nuclear envelope and the peripheral ER organized into ER sheets and tubules. ER also forms physical contact sites with all other cellular organelles and with the plasma membrane. Both form and function of the ER are highly adaptive, with a potent capacity to respond to transient changes in environmental cues such as nutritional fluctuations. However, under obesity-induced chronic stress, the ER fails to adapt, leading to ER dysfunction and the development of metabolic pathologies such as insulin resistance and fatty liver disease. Here, we discuss how the remodeling of ER structure and contact sites with other organelles results in diversification of metabolic function and how perturbations to this structural flexibility by chronic overnutrition contribute to ER dysfunction and metabolic pathologies in obesity.


Asunto(s)
Retículo Endoplásmico , Transducción de Señal , Humanos , Retículo Endoplásmico/metabolismo , Membrana Celular/metabolismo , Membrana Nuclear/metabolismo , Obesidad , Estrés del Retículo Endoplásmico/fisiología
8.
J Clin Invest ; 133(1)2023 01 03.
Artículo en Inglés | MEDLINE | ID: mdl-36346671

RESUMEN

Three principal ER quality-control mechanisms, namely, the unfolded protein response, ER-associated degradation (ERAD), and ER-phagy are each important for the maintenance of ER homeostasis, yet how they are integrated to regulate ER homeostasis and organellar architecture in vivo is largely unclear. Here we report intricate crosstalk among the 3 pathways, centered around the SEL1L-HRD1 protein complex of ERAD, in the regulation of organellar organization in ß cells. SEL1L-HRD1 ERAD deficiency in ß cells triggers activation of autophagy, at least in part, via IRE1α (an endogenous ERAD substrate). In the absence of functional SEL1L-HRD1 ERAD, proinsulin is retained in the ER as high molecular weight conformers, which are subsequently cleared via ER-phagy. A combined loss of both SEL1L and autophagy in ß cells leads to diabetes in mice shortly after weaning, with premature death by approximately 11 weeks of age, associated with marked ER retention of proinsulin and ß cell loss. Using focused ion beam scanning electron microscopy powered by deep-learning automated image segmentation and 3D reconstruction, our data demonstrate a profound organellar restructuring with a massive expansion of ER volume and network in ß cells lacking both SEL1L and autophagy. These data reveal at an unprecedented detail the intimate crosstalk among the 3 ER quality-control mechanisms in the dynamic regulation of organellar architecture and ß cell function.


Asunto(s)
Degradación Asociada con el Retículo Endoplásmico , Endorribonucleasas , Ratones , Animales , Endorribonucleasas/metabolismo , Proinsulina/genética , Proinsulina/metabolismo , Ubiquitina-Proteína Ligasas/genética , Proteínas Serina-Treonina Quinasas/metabolismo , Retículo Endoplásmico/metabolismo , Proteínas/metabolismo
9.
bioRxiv ; 2023 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-36865319

RESUMEN

Mitochondrial reactive oxygen species (mROS) are central to physiology. While excess mROS production has been associated with several disease states, its precise sources, regulation, and mechanism of generation in vivo remain unknown, limiting translational efforts. Here we show that in obesity, hepatic ubiquinone (Q) synthesis is impaired, which raises the QH 2 /Q ratio, driving excessive mROS production via reverse electron transport (RET) from site I Q in complex I. Using multiple complementary genetic and pharmacological models in vivo we demonstrated that RET is critical for metabolic health. In patients with steatosis, the hepatic Q biosynthetic program is also suppressed, and the QH 2 /Q ratio positively correlates with disease severity. Our data identify a highly selective mechanism for pathological mROS production in obesity, which can be targeted to protect metabolic homeostasis.

10.
J Bioenerg Biomembr ; 43(1): 53-8, 2011 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-21271281

RESUMEN

Hypothalamic inflammation and dysfunction are common features of experimental obesity. An imbalance between caloric intake and energy expenditure is generated as a consequence of this inflammation, leading to the progressive increase of body adiposity. Thermogenesis, is one of the main functions affected by obesity-linked hypothalamic dysfunction and the complete characterization of the mechanisms involved in this process may offer new therapeutic perspectives for obesity. The brown adipose tissue is an important target for hypothalamic action in thermogenesis. This tissue has been thoroughly studied in rodents and hibernating mammals; however, until recently, its advocated role in human thermogenesis was neglected due to the lack of substantial evidence of its presence in adult humans. The recent demonstration of the presence of functional brown adipose tissue in adult humans has renovated the interest in this tissue. Here, we review some of the work that shows how inflammation and dysfunction of the hypothalamus can control brown adipose tissue activity and how this can impact on whole body thermogenesis and energy expenditure.


Asunto(s)
Tejido Adiposo Pardo/fisiología , Hipotálamo/fisiopatología , Inflamación/fisiopatología , Modelos Biológicos , Obesidad/fisiopatología , Termogénesis/fisiología , Adulto , Humanos , Insulina/metabolismo , Leptina/metabolismo
11.
Cell Metab ; 33(2): 319-333.e6, 2021 02 02.
Artículo en Inglés | MEDLINE | ID: mdl-33340456

RESUMEN

Endoplasmic reticulum stress (ERS) has a pathophysiological role in obesity-associated insulin resistance. Yet, the coordinated tissue response to ERS remains unclear. Increased connexin 43 (Cx43)-mediated intercellular communication has been implicated in tissue-adaptive and -maladaptive response to various chronic stresses. Here, we demonstrate that in hepatocytes, ERS results in increased Cx43 expression and cell-cell coupling. Co-culture of ER-stressed "donor" cells resulted in intercellular transmission of ERS and dysfunction to ERS-naive "recipient" cells ("bystander response"), which could be prevented by genetic or pharmacologic suppression of Cx43. Hepatocytes from obese mice were able to transmit ERS to hepatocytes from lean mice, and mice lacking liver Cx43 were protected from diet-induced ERS, insulin resistance, and hepatosteatosis. Taken together, our results indicate that in obesity, the increased Cx43-mediated cell-cell coupling allows intercellular propagation of ERS. This novel maladaptive response to over-nutrition exacerbates the tissue ERS burden, promoting hepatosteatosis and impairing whole-body glucose metabolism.


Asunto(s)
Hepatocitos/metabolismo , Obesidad/metabolismo , Animales , Línea Celular , Técnicas de Cocultivo , Conexina 43/deficiencia , Conexina 43/metabolismo , Estrés del Retículo Endoplásmico , Femenino , Humanos , Masculino , Ratones , Ratones Congénicos , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos
12.
Sci Signal ; 14(713): eabf2059, 2021 Dec 14.
Artículo en Inglés | MEDLINE | ID: mdl-34905386

RESUMEN

Chronic metabolic inflammation is a key feature of obesity, insulin resistance, and diabetes. Here, we showed that altered regulation of the Ca2+ channel inositol trisphosphate receptor (IP3R) was an adipocyte-intrinsic event involved in the emergence and propagation of inflammatory signaling and the resulting insulin resistance. Inflammation induced by cytokine exposure in vitro or by obesity in vivo led to increases in the abundance and activity of IP3Rs and in the phosphorylation of the Ca2+-dependent kinase CaMKII in adipocytes in a manner dependent on the kinase JNK. In mice, adipocyte-specific loss of IP3R1/2 protected against adipose tissue inflammation and insulin resistance, despite the mice exhibiting substantial diet-induced weight gain. Thus, this work suggests that increased IP3R activity is a key link between obesity, inflammation, and insulin resistance. These data also suggest that approaches to target IP3R-mediated Ca2+ homeostasis in adipocytes may offer new therapeutic opportunities against metabolic diseases, especially because GWAS studies also implicate this locus in human obesity.


Asunto(s)
Adipocitos , Obesidad , Humanos , Inflamación , Transducción de Señal
13.
Biochim Biophys Acta ; 1788(7): 1517-22, 2009 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-19376087

RESUMEN

In this work, we compared the effect of K+ on vesicles derived from the longitudinal (LSR) and terminal cisternae (HSR) of rabbit white muscle. In HSR, K+ was found to inhibit both the Ca2+ accumulation and the heat released during ATP hydrolysis by the Ca2+-ATPase (SERCA1). This was not observed in LSR. Valinomycin abolished the HSR Ca2+-uptake inhibition promoted by physiological K+ concentrations, but it did not modify the thermogenic activity of the Ca2+ pump. The results with HSR are difficult to interpret, assuming that a single K+ is binding to either the ryanodine channel or to the Ca2+-ATPase. It is suggested that an increase of K+ in the assay medium alters the interactions among the various proteins found in HSR, thus modifying the properties of both the ryanodine channel and SERCA1.


Asunto(s)
Señalización del Calcio , Calcio/metabolismo , Fibras Musculares de Contracción Rápida/metabolismo , Potasio/metabolismo , Retículo Sarcoplasmático/metabolismo , Animales , Calor , Hidrólisis , Conejos , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismo
14.
Am J Physiol Heart Circ Physiol ; 297(2): H556-63, 2009 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19525379

RESUMEN

Short-term response to cold promotes a small but significant rise in serum T3 in euthyroid rabbits, where the heart is an important target of T3 action. In this work, we measured changes in sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA2a) and phospholamban (PLB) in hearts of hypo- and hyperthyroid rabbits and compared them with modifications induced by short- and long-term cold exposure. Short-term cold exposure promotes a small increase in T3 and, similar to hyperthyroidism, induces an increase of heart SERCA2a expression. The total PLB content does not change in hyperthyroidism, but short-term cold exposure promotes a significant decrease in total PLB and an increase in the ratio between phosphorylated and total PLB. The temperature of a given tissue depends on the balance between the heat provided by blood circulation and the rate of heat production by the tissue. In an attempt to evaluate the heat contribution of cardiac tissue, we measured mitochondrial respiration in permeabilized cardiac muscle and heat produced by cardiac sarcoplasmic reticulum (SR) during Ca(2+) transport. We observed that there was an increase in oxygen consumption and heat production during Ca(2+) transport by cardiac SR in both hyperthyroidism and short-term cold exposure. In contrast, both the mitochondrial respiration rate and heat derived from Ca(2+) transport were decreased in hypothyroid rabbits. The heart changes in oxygen consumption, SERCA2a-PLB ratio, and Ca(2+)-ATPase activity detected during short-term cold exposure were abolished after cold adaptation. We hypothesize that the transient rise in serum T3 contributes to the short-term response to cold exposure.


Asunto(s)
Regulación de la Temperatura Corporal/fisiología , Proteínas de Unión al Calcio/metabolismo , Miocardio/metabolismo , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismo , Triyodotironina/metabolismo , Adaptación Fisiológica/fisiología , Animales , Calcio/metabolismo , Citrato (si)-Sintasa/metabolismo , Frío , Metabolismo Energético/fisiología , Calor , Hipertiroidismo/metabolismo , Hipotiroidismo/metabolismo , Masculino , Mitocondrias Cardíacas/metabolismo , Consumo de Oxígeno/fisiología , Conejos , Tiroxina/metabolismo , Tiroxina/farmacología
15.
BMJ Open ; 9(5): e023729, 2019 05 24.
Artículo en Inglés | MEDLINE | ID: mdl-31129571

RESUMEN

OBJECTIVE: To summarise the effects of herbal medications for the prevention of anxiety, depression, pain, and postoperative nausea and vomiting (PONV) in patients undergoing laparoscopic, obstetrical/gynaecological or cardiovascular surgical procedures. METHODS: Searches of MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and LILACS up until January 2018 were performed to identify randomised controlled trials (RCTs). We included RCTs or quasi-RCTs evaluating any herbal medication among adults undergoing laparoscopic, obstetrical/gynaecological or cardiovascular surgeries. The primary outcomes were anxiety, depression, pain and PONV. We used the Grading of Recommendations Assessment, Development and Evaluation approach to rate overall certainty of the evidence for each outcome. RESULTS: Eleven trials including 693 patients were eligible. Results from three RCTs suggested a statistically significant reduction in vomiting (relative risk/risk ratio (RR) 0.57; 95% CI 0.38 to 0.86) and nausea (RR 0.69; 95% CI 0.50 to 0.96) with the use of Zingiber officinale (ginger) compared with placebo in both laparoscopic and obstetrical/gynaecological surgeries. Results suggested a non-statistically significantly reduction in the need for rescue medication for pain (RR 0.52; 95% CI 0.13 to 2.13) with Rosa damascena (damask rose) and ginger compared with placebo in laparoscopic and obstetrical/gynaecological surgery. None of the included studies reported on adverse events (AEs). CONCLUSIONS: There is very low-certainty evidence regarding the efficacy of both Zingiber officinale and Rosa damascena in reducing vomiting (200 fewer cases per 1000; 288 fewer to 205 fewer), nausea (207 fewer cases per 1000; 333 fewer to 27 fewer) and the need for rescue medication for pain (666 fewer cases per 1000; 580 fewer to 752 more) in patients undergoing either laparoscopic or obstetrical/gynaecological surgeries. Among our eligible studies, there was no reported evidence on AEs. PROSPERO REGISTRATION NUMBER: CRD42016042838.


Asunto(s)
Ansiedad/prevención & control , Depresión/prevención & control , Dolor/prevención & control , Fitoterapia , Preparaciones de Plantas/uso terapéutico , Náusea y Vómito Posoperatorios/prevención & control , Cuidados Preoperatorios/métodos , Ensayos Clínicos Controlados Aleatorios como Asunto , Humanos
16.
Biochim Biophys Acta ; 1768(6): 1498-505, 2007 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-17466935

RESUMEN

The sarcoplasmic reticulum Ca(2+) ATPase 1 (SERCA 1) is able to handle the energy derived from ATP hydrolysis in such a way as to determine the parcel of energy that is used for Ca(2+) transport and the fraction that is converted into heat. In this work we measured the heat production by SERCA 1 in the two sarcoplasmic reticulum (SR) fractions: the light fraction (LSR), which is enriched in SERCA and the heavy fraction (HSR), which contains both the SERCA and the ryanodine Ca(2+) channel. We verified that although HSR cleaved ATP at faster rate than LSR, the amount of heat released during ATP hydrolysis by HSR was smaller than that measured by LSR. Consequently, the amount of heat released per mol of ATP cleaved (DeltaH(cal)) by HSR was lower compared to LSR. In HSR, the addition of 5 mM Mg(2+) or ruthenium red, conditions that close the ryanodine Ca(2+) channel, promoted a decrease in the ATPase activity, but the amount of heat released during ATP hydrolysis remained practically the same. In this condition, the DeltaH(cal) values of ATP hydrolysis increased significantly. Neither Mg(2+) nor ruthenium red had effect on LSR. Thus, we conclude that heat production by SERCA 1 depends on the region of SR in which the enzyme is inserted and that in HSR, the DeltaH(cal) of ATP hydrolysis by SERCA 1 depends on whether the ryanodine Ca(2+) channel is opened or closed.


Asunto(s)
Músculo Esquelético/enzimología , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismo , Retículo Sarcoplasmático/enzimología , Termogénesis/fisiología , Animales , Western Blotting , Calcio/metabolismo , Músculo Esquelético/fisiología , Conejos , Retículo Sarcoplasmático/fisiología
17.
Endocrinology ; 149(12): 6262-71, 2008 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18703625

RESUMEN

Brown adipose tissue (BAT) is involved in rat and mice thermoregulation, and heat produced by BAT depends on the concerted action of thyroid hormones and catecholamines. Little is known about cold-induced thermogenesis in mammals that have little or no BAT, such as rabbits. In these animals, thermogenesis primarily occurs in skeletal muscle. In this work, we have studied the effect of cold acclimation (4 C for 10 d) in normal and hypothyroid rabbits. It is known that hypothyroid rats die after a few hours of cold exposure. We now show that, different from rats, hypothyroid rabbits sustain their body temperature and survive after 10 d cold exposure. When compared with rabbits kept at room temperature, the muscles of cold-exposed rabbits showed a dark red color characteristic of oxidative muscle fibers. According to this pattern, we observed that in both normal and hypothyroid rabbits, cold exposure promotes an increase in oxygen consumption by skeletal muscle mitochondria. Moreover, in red muscle, cold acclimation induces an increase in the expression and activity of sarcoplasmic reticulum Ca(2+) ATPase isoform 1 (SERCA1), one of the muscle enzymes involved in heat production. We conclude that rabbit cold tolerance is probably related to increased muscle oxidative metabolism and heat production by SERCA1 and that these changes are not completely dependent on normal thyroid function.


Asunto(s)
Frío , Hipotiroidismo/metabolismo , Mitocondrias Musculares/metabolismo , Músculo Esquelético/metabolismo , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismo , Animales , Western Blotting , Peso Corporal , Ingestión de Alimentos , Hipotiroidismo/sangre , Hipotiroidismo/fisiopatología , Masculino , Mitocondrias Musculares/fisiología , Músculo Esquelético/fisiología , Consumo de Oxígeno/fisiología , Conejos , Termogénesis , Tiroxina/sangre , Factores de Tiempo , Triyodotironina/sangre
18.
Nat Med ; 24(3): 292-303, 2018 03.
Artículo en Inglés | MEDLINE | ID: mdl-29400713

RESUMEN

Adipocytes possess remarkable adaptive capacity to respond to nutrient excess, fasting or cold exposure, and they are thus an important cell type for the maintenance of proper metabolic health. Although the endoplasmic reticulum (ER) is a critical organelle for cellular homeostasis, the mechanisms that mediate adaptation of the ER to metabolic challenges in adipocytes are unclear. Here we show that brown adipose tissue (BAT) thermogenic function requires an adaptive increase in proteasomal activity to secure cellular protein quality control, and we identify the ER-localized transcription factor nuclear factor erythroid 2-like 1 (Nfe2l1, also known as Nrf1) as a critical driver of this process. We show that cold adaptation induces Nrf1 in BAT to increase proteasomal activity and that this is crucial for maintaining ER homeostasis and cellular integrity, specifically when the cells are in a state of high thermogenic activity. In mice, under thermogenic conditions, brown-adipocyte-specific deletion of Nfe2l1 (Nrf1) resulted in ER stress, tissue inflammation, markedly diminished mitochondrial function and whitening of the BAT. In mouse models of both genetic and dietary obesity, stimulation of proteasomal activity by exogenously expressing Nrf1 or by treatment with the proteasome activator PA28α in BAT resulted in improved insulin sensitivity. In conclusion, Nrf1 emerges as a novel guardian of brown adipocyte function, providing increased proteometabolic quality control for adapting to cold or to obesity.


Asunto(s)
Tejido Adiposo Pardo/metabolismo , Retículo Endoplásmico/genética , Factor 1 Relacionado con NF-E2/genética , Obesidad/genética , Complejo de la Endopetidasa Proteasomal/genética , Aclimatación/genética , Aclimatación/fisiología , Animales , Frío , Retículo Endoplásmico/metabolismo , Estrés del Retículo Endoplásmico/genética , Eliminación de Gen , Homeostasis , Humanos , Inflamación/genética , Inflamación/fisiopatología , Resistencia a la Insulina/genética , Mitocondrias/genética , Mitocondrias/metabolismo , Modelos Animales , Obesidad/fisiopatología , Complejo de la Endopetidasa Proteasomal/metabolismo , Termogénesis/genética
19.
Cell Rep ; 21(2): 393-402, 2017 Oct 10.
Artículo en Inglés | MEDLINE | ID: mdl-29020626

RESUMEN

Deterioration of metabolic health is a hallmark of aging and generally assumed to be detrimental to longevity. Exposure to a high-calorie diet impairs metabolism and accelerates aging; conversely, calorie restriction (CR) prevents age-related metabolic diseases and extends lifespan. However, it is unclear whether preservation of metabolic health is sufficient to extend lifespan. We utilized a genetic mouse model lacking Fabp4/5 that confers protection against metabolic diseases and shares molecular and lipidomic features with CR to address this question. Fabp-deficient mice exhibit extended metabolic healthspan, with protection against insulin resistance and glucose intolerance, inflammation, deterioration of adipose tissue integrity, and fatty liver disease. Surprisingly, however, Fabp-deficient mice did not exhibit any extension of lifespan. These data indicate that extension of metabolic healthspan in the absence of CR can be uncoupled from lifespan, indicating the potential for independent drivers of these pathways, at least in laboratory mice.


Asunto(s)
Tejido Adiposo/metabolismo , Proteínas de Unión a Ácidos Grasos/genética , Longevidad , Proteínas de Neoplasias/genética , Tejido Adiposo/crecimiento & desarrollo , Animales , Proteínas de Unión a Ácidos Grasos/metabolismo , Hígado Graso/genética , Femenino , Resistencia a la Insulina , Metabolismo de los Lípidos , Masculino , Ratones , Ratones Endogámicos C57BL , Proteínas de Neoplasias/metabolismo
20.
BMJ Open ; 7(7): e014290, 2017 07 26.
Artículo en Inglés | MEDLINE | ID: mdl-28751485

RESUMEN

INTRODUCTION: Postoperative nausea and vomiting (PONV) affect approximately 80% of surgical patients and is associated with increased length of hospital stay and systemic costs. Preoperative and postoperative pain, anxiety and depression are also commonly reported. Recent evidence regarding their safety and effectiveness has not been synthesised. The aim of this systematic review is to evaluate the efficacy and safety of herbal medications for the treatment and prevention of anxiety, depression, pain and PONV in patients undergoing laparoscopic, obstetrical/gynaecological and cardiovascular surgical procedures. METHODS AND ANALYSIS: The following electronic databases will be searched up to 1 October 2016 without language or publication status restrictions: CENTRAL, MEDLINE, EMBASE, CINAHL, Web of Science and LILACS. Randomised clinical trials enrolling adult surgical patients undergoing laparoscopic, obstetrical/gynaecological and cardiovascular surgeries and managed with herbal medication versus a control group (placebo, no intervention or active control) prophylactically or therapeutically will be considered eligible. Outcomes of interest will include the following: anxiety, depression, pain, nausea and vomiting. A team of reviewers will complete title and abstract screening and full-text screening for identified hits independently and in duplicate. Data extraction, risk of bias assessments and evaluation of the overall quality of evidence for each relevant outcome reported will be conducted independently and in duplicate using the Grading of Recommendations Assessment Development and Evaluation classification system. Dichotomous data will be summarised as risk ratios; continuous data will be summarised as standard average differences with 95% CIs. ETHICS AND DISSEMINATION: This is one of the first efforts to systematically summarise existing evidence evaluating the use of herbal medications in laparoscopic, obstetrical/gynaecological and cardiovascular surgical patients. The findings of this review will be disseminated through peer-reviewed publications and conference presentations. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42016042838.


Asunto(s)
Preparaciones de Plantas/uso terapéutico , Complicaciones Posoperatorias/prevención & control , Complicaciones Posoperatorias/terapia , Náusea y Vómito Posoperatorios/prevención & control , Náusea y Vómito Posoperatorios/terapia , Adulto , Ansiedad/prevención & control , Ansiedad/terapia , Depresión/prevención & control , Depresión/terapia , Humanos , Dolor Postoperatorio/prevención & control , Dolor Postoperatorio/terapia , Fitoterapia , Ensayos Clínicos Controlados Aleatorios como Asunto , Proyectos de Investigación , Revisiones Sistemáticas como Asunto
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