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BACKGROUND AND AIMS: Hepatic ischemia-reperfusion (IR) injury is the most common complication that occurs in liver surgery and hemorrhagic shock. ATP citrate lyase (Acly) plays a pivotal role in chromatin modification via generating acetyl-CoA for histone acetylation to influence biological processes. We aim to examine the roles of Acly, which is highly expressed in hepatocytes, in liver IR injury. APPROACH AND RESULTS: The functions of Acly in hepatic IR injury were examined in the mouse model with a hepatocyte-specific knockout of Acly . The Acly target genes were analyzed by CUT&RUN assay and RNA sequencing. The relationship between the susceptibility of the steatotic liver to IR and Acly was determined by the gain of function studies in mice. Hepatic deficiency of Acly exacerbated liver IR injury. IR induced Acly nuclear translocation in hepatocytes, which spatially fueled nuclear acetyl-CoA. This alteration was associated with enhanced acetylation of H3K9 and subsequent activation of the Foxa2 signaling pathway. Nuclear localization of Acly enabled Foxa2-mediated protective effects after hypoxia-reperfusion in cultured hepatocytes, while cytosolic Acly demonstrated no effect. The presence of steatosis disrupted Acly nuclear translocation. In the steatotic liver, restoration of Acly nuclear localization through overexpression of Rspondin-1 or Rspondin-3 ameliorated the IR-induced injury. CONCLUSIONS: Our results indicate that Acly regulates histone modification by means of nuclear AcCoA production in hepatic IR. Disruption of Acly nuclear translocation increases the vulnerability of the steatotic liver to IR. Nuclear Acly thus may serve as a potential therapeutic target for future interventions in hepatic IR injury, particularly in the context of steatosis.
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Although visceral adipocytes located within the body's central core are maintained at approximately 37°C, adipocytes within bone marrow, subcutaneous, and dermal depots are found primarily within the peripheral shell and generally exist at cooler temperatures. Responses of brown and beige/brite adipocytes to cold stress are well studied; however, comparatively little is known about mechanisms by which white adipocytes adapt to temperatures below 37°C. Here, we report that adaptation of cultured adipocytes to 31°C, the temperature at which distal marrow adipose tissues and subcutaneous adipose tissues often reside, increases anabolic and catabolic lipid metabolism, and elevates oxygen consumption. Cool adipocytes rely less on glucose and more on pyruvate, glutamine, and, especially, fatty acids as energy sources. Exposure of cultured adipocytes and gluteal white adipose tissue (WAT) to cool temperatures activates a shared program of gene expression. Cool temperatures induce stearoyl-CoA desaturase-1 (SCD1) expression and monounsaturated lipid levels in cultured adipocytes and distal bone marrow adipose tissues (BMATs), and SCD1 activity is required for acquisition of maximal oxygen consumption at 31°C.
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Adipocitos Blancos/metabolismo , Regulación de la Temperatura Corporal/fisiología , Adaptación Fisiológica , Adipocitos/metabolismo , Adipocitos/fisiología , Adipocitos Marrones/metabolismo , Adipocitos Blancos/fisiología , Tejido Adiposo/metabolismo , Tejido Adiposo Blanco/metabolismo , Animales , Frío , Ácidos Grasos/metabolismo , Femenino , Metabolismo de los Lípidos/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Consumo de Oxígeno , Ratas , Ratas Sprague-Dawley , Estearoil-CoA Desaturasa/metabolismoRESUMEN
CRISPR/Cas9 has enabled inducible gene knockout in numerous tissues; however, its use has not been reported in brown adipose tissue (BAT). Here, we developed the brown adipocyte CRISPR (BAd-CRISPR) methodology to rapidly interrogate the function of one or multiple genes. With BAd-CRISPR, an adeno-associated virus (AAV8) expressing a single guide RNA (sgRNA) is administered directly to BAT of mice expressing Cas9 in brown adipocytes. We show that the local administration of AAV8-sgRNA to interscapular BAT of adult mice robustly transduced brown adipocytes and ablated expression of adiponectin, adipose triglyceride lipase, fatty acid synthase, perilipin 1, or stearoyl-CoA desaturase 1 by >90%. Administration of multiple AAV8 sgRNAs led to simultaneous knockout of up to three genes. BAd-CRISPR induced frameshift mutations and suppressed target gene mRNA expression but did not lead to substantial accumulation of off-target mutations in BAT. We used BAd-CRISPR to create an inducible uncoupling protein 1 (Ucp1) knockout mouse to assess the effects of UCP1 loss on adaptive thermogenesis in adult mice. Inducible Ucp1 knockout did not alter core body temperature; however, BAd-CRISPR Ucp1 mice had elevated circulating concentrations of fibroblast growth factor 21 and changes in BAT gene expression consistent with heat production through increased peroxisomal lipid oxidation. Other molecular adaptations predict additional cellular inefficiencies with an increase in both protein synthesis and turnover, and mitochondria with reduced reliance on mitochondrial-encoded gene expression and increased expression of nuclear-encoded mitochondrial genes. These data suggest that BAd-CRISPR is an efficient tool to speed discoveries in adipose tissue biology.
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Tejido Adiposo Pardo/metabolismo , Sistemas CRISPR-Cas , Animales , Factores de Crecimiento de Fibroblastos/genética , Factores de Crecimiento de Fibroblastos/metabolismo , Técnicas de Inactivación de Genes , Ratones , Ratones Noqueados , Proteína Desacopladora 1/genética , Proteína Desacopladora 1/metabolismoRESUMEN
Whether the stomach influences the progression of nonalcoholic steatohepatitis (NASH) remains largely unknown. Ghrelin, a 28-amino acid gastric hormone, is critical for the regulation of energy metabolism and inflammation. We investigated whether ghrelin affects the progression of NASH. NASH was induced with lipopolysaccharide (LPS; 240 µg/kg/day) in male C57BL/6J mice with high-fat diet (HFD). Ghrelin (11 nmol/kg/day) was administrated by a subcutaneous mini-pump. Liver steatosis, inflammation, and fibrosis were assessed. Kupffer cells and hepatocytes isolated from wild type, GHSR1a-/- or PPARγ+/- mice were cocultured to determine the cellular and molecular mechanism by which ghrelin ameliorates NASH. A low concentration of LPS activates the Kupffer cells, leading to the development of NASH in mice fed HFD. Ghrelin blocked the progression of NASH induced by LPS via GHSR1a-mediated attenuation of Kupffer cells M1 polarization. GHSR1a was detected in Kupffer cells isolated from wild-type mice but not in GHSR1a deficient animals. Upon binding with ghrelin, internalization of GHSR1a occurred. Ghrelin reduced levels of tumor necrosis factor-α and inducible nitricoxide synthase while increasing Arg1 in Kupffer cells treated with LPS. Ghrelin markedly attenuated the upregulation of lipid accumulation induced by the supernatant of Kupffer cells under both basal and LPS-treated conditions. Deficiency of PPARγ significantly reduced the effect of LPS on the hepatic steatosis in mice and in cultured hepatocytes. Our studies indicate that the stomach may improve the development of NASH via ghrelin. Ghrelin may serve as a marker and therapeutic target for NASH.
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Ghrelina/farmacología , Macrófagos del Hígado/metabolismo , Enfermedad del Hígado Graso no Alcohólico/prevención & control , Receptores de Ghrelina/metabolismo , Estómago/fisiología , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Animales , Arginasa/metabolismo , Polaridad Celular , Células Cultivadas , Dieta Alta en Grasa , Ghrelina/metabolismo , Hepatocitos/metabolismo , Lipopolisacáridos , Hígado/patología , Cirrosis Hepática/patología , Activación de Macrófagos/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Óxido Nítrico Sintasa de Tipo II/metabolismo , Enfermedad del Hígado Graso no Alcohólico/patología , PPAR gamma/genética , Receptores de Ghrelina/genéticaRESUMEN
Gastric mechanistic target of rapamycin (mTOR) signaling is inversely associated with the expression and secretion of ghrelin, a 28-aa peptide hormone produced by gastric X/A-like cells. Ghrelin contributes to obesity and hepatic steatosis. We sought to control global lipid metabolism via the manipulation of gastric mTOR signaling in X/A-like cells. We established a ghrl-cre transgene in which the Cre enzyme is expressed in X/A-like cells under the control of the ghrelin-promoter. mTORflox/flox and tuberous sclerosis 1 (TSC1)flox/flox mice were separately bred with ghrl-cre mice to generate mTOR-ghrl-cre or TSC1-ghrl-cre mice, within which mTOR signaling was suppressed or activated, respectively. Lipid metabolism in liver and adipose depots was analyzed. Under the control of the ghrelin-promoter, the Cre enzyme was exclusively expressed in stomach X/A-like cells in adult animals. Knockout of mTOR in X/A-like cells increased circulating acyl-ghrelin and promoted hepatic lipogenesis with effects on adipose depots. Activation of mTOR signaling by deletion of its upstream inhibitor, TSC1, decreased ghrelin expression and secretion, altering lipid metabolism as evidenced by resistance to high-fat diet-induced obesity and hepatic steatosis. Both ghrelin administration and injection of rapamycin, an inhibitor of mTOR, altered the phenotypes of TSC1-ghrl-cre mice. Conclusion: Gastric mTOR signaling in X/A-like cells contributes to organism lipid homeostasis by regulating hepatic and adipose lipid metabolism. Gastric mTOR signaling may provide an alternative strategy for intervention in lipid disorders.
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Células Enteroendocrinas/metabolismo , Ghrelina/metabolismo , Metabolismo de los Lípidos , Serina-Treonina Quinasas TOR/metabolismo , Animales , Homeostasis , Hígado/metabolismo , Masculino , Ratones , Ratones Transgénicos , Proteína 1 del Complejo de la Esclerosis Tuberosa/genéticaRESUMEN
Leucine-rich repeat G protein-coupled receptors (LGRs) and their endogenous ligands R-spondin1-4 (Rspo) are critical in embryonic development and in maintenance of stem cells. The functions of the Rspo-LGR system in differentiated cells remain uncharacterized. In this study, the expression profiles of LGRs and Rspos were characterized in mature hepatocytes. A liver-specific knockout of LGR4 in mouse was generated and used to study hepatic ischemia/reperfusion-induced injury (HIRI) as well as lipopolysaccharide/ D- galactosamine (LPS/D-Gal)-induced liver injury. We have demonstrated that, in adult liver, LGR4 is expressed in hepatocytes and responds to Rspo1 with internalization. Rspo1 is responsive to various nutritional states and to mTOR signaling. Activation of LGR4 by Rspo1 significantly reduced tumor necrosis factor-α (TNFα)-induced cell death, and levels of NF-κB-p65 and caspase-3 in cultured hepatocytes. Knockdown of hepatic LGR4 rendered hepatocytes more vulnerable to TNFα-induced damage in cultured primary cells and in the setting of HIRI and LPS/D-Gal-induced liver injury. Rspo1 potentiated both basal and Wnt3a-induced stabilization of ß-catenin. Disruption of ß-catenin signaling reversed the protective effects of Rspo1 on TNFα-induced hepatocyte toxicity. LGR4 knockdown increased nuclear translocation of NF-κB-p65 in response to acute injury. Overexpression of IKKß attenuated the protective effects of Rspo1 on TNFα-induced cell death. In conclusion, the Rspo1-LGR4 system represents a novel pathway for cytoprotection and modulation of stress-induced tissue damage. NEW & NOTEWORTHY Functional LGR4 is present in mature hepatocytes. R-spodin1 protects hepatocytes from tumor necrosis factor-α-induced cell death. Liver-specific knockdown of LGR4 renders liver more susceptible to acute injury. LGR4 protects hepatocytes from injury by inhibition of NF-κB signaling.
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Enfermedad Hepática Inducida por Sustancias y Drogas/metabolismo , Hepatocitos/metabolismo , Hígado/lesiones , Receptores Acoplados a Proteínas G/metabolismo , Animales , Hígado/metabolismo , Hepatopatías/metabolismo , Ratones Endogámicos C57BL , Ratones Noqueados , FN-kappa B/metabolismo , Sustancias Protectoras/farmacología , Transducción de Señal/fisiología , Factor de Transcripción ReIA/metabolismoRESUMEN
Hepatic steatosis renders liver more vulnerable to ischemia/reperfusion injury (IRI), which commonly occurs in transplantation, trauma, and liver resection. The underlying mechanism is not fully characterized. We aimed to clarify the role of mechanistic target of rapamycin (mTOR) signaling in hepatic ischemia/reperfusion injury (HIRI) in normal and steatotic liver using Alb-TSC1-/- (AT) and Alb-mTOR-/- (Am) transgenic mice. Steatotic liver induced by high-fat diet was more vulnerable to IRI. Activation of hepatic mTOR in AT mice decreased lipid accumulation attenuated HIRI as measured by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining, circulating levels of alanine aminotransferase and lactate dehydrogenase, and inflammatory mediators such as monocyte chemoattractant protein 1 (MCP-1), TNF-α, and IL-6 and hepatic cleaved caspase 3 in mice fed either a normal chow diet or a high-fat diet. The effects of mTOR activation on hepatic cleaved caspase 3 were reversed by rapamycin, an inhibitor of mTOR signaling. Inhibition of hepatic mTOR in Am mice increased hepatic lipid deposition and HIRI. The increment in hepatic susceptibility to IRI was significantly attenuated by pretreatment with IKKß inhibitor. Further, suppression of mTOR facilitated nuclear translocation of NF-κB p65. In conclusion, our study suggests that mTOR activity in hepatocytes decreases hepatic vulnerability to injury through a mechanism dependent on NF-κB proinflammatory cytokine signaling pathway in both normal and steatotic liver.-Li, Z., Zhang, J., Mulholland, M., Zhang, W. mTOR activation protects liver from ischemia/reperfusion-induced injury through NF-κB pathway.
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Hígado Graso/complicaciones , Daño por Reperfusión/prevención & control , Serina-Treonina Quinasas TOR/metabolismo , Factor de Transcripción ReIA/metabolismo , Proteínas Supresoras de Tumor/metabolismo , Animales , Dieta Alta en Grasa , Hígado Graso/inducido químicamente , Regulación de la Expresión Génica/fisiología , Técnicas de Silenciamiento del Gen , Quinasa I-kappa B/metabolismo , Metabolismo de los Lípidos , Hígado/metabolismo , Ratones , Ratones Noqueados , Transducción de Señal/fisiología , Serina-Treonina Quinasas TOR/genética , Factor de Transcripción ReIA/genética , Proteína 1 del Complejo de la Esclerosis Tuberosa , Proteínas Supresoras de Tumor/genéticaRESUMEN
Although ghrelin has been demonstrated to stimulate energy intake and storage through a central mechanism, its effect on hepatic lipid metabolism remains largely uncharacterized. Ghrelin receptor antagonism or gene deletion significantly decreased obesity-associated hepatic steatosis by suppression of de novo lipogenesis, whereas exogenous ghrelin stimulated lipogenesis, leading to hepatic lipid accumulation in mice. The effects of ghrelin were mediated by direct activation of its receptor on hepatocytes. Cultured hepatocytes responded to ghrelin with increased lipid content and expression of lipogenesis-related genes. Ghrelin increased phosphorylation of S6, the downstream target of mammalian target of rapamycin (mTOR) signaling in cultured hepatocytes, whereas ghrelin receptor antagonism reduced hepatic phosphorylation of S6 in db/db mice. Inhibition of mTOR signaling by rapamycin markedly attenuated ghrelin-induced up-regulation of lipogenesis in hepatocytes, whereas activation of hepatic mTOR signaling by deletion of TSC1 increased hepatic lipogenesis. By interacting with peroxisome proliferator-activated receptor-γ (PPARγ), mTOR mediates the ghrelin-induced up-regulation of lipogenesis in hepatocytes. The stimulatory effect of ghrelin on hepatic lipogenesis was significantly attenuated by PPARγ antagonism in cultured hepatocytes and in PPARγ gene-deficient mice. Our study indicates that ghrelin activates its receptor on hepatocytes to promote lipogenesis via a mechanism involving the mTOR-PPARγ signaling pathway.
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Ghrelina/farmacología , Lipogénesis/efectos de los fármacos , Hígado/metabolismo , PPAR gamma/metabolismo , Transducción de Señal/efectos de los fármacos , Serina-Treonina Quinasas TOR/metabolismo , Animales , Hígado Graso/metabolismo , Hígado Graso/patología , Eliminación de Gen , Hepatocitos/efectos de los fármacos , Hepatocitos/metabolismo , Hepatocitos/patología , Hígado/efectos de los fármacos , Hígado/patología , Masculino , Ratones Endogámicos C57BL , Ratones Noqueados , Unión Proteica/efectos de los fármacos , Receptores de Ghrelina/metabolismoRESUMEN
MAIN CONCLUSION: The triose phosphate use limitation was studied using long-term and short term changes in capacity. The TPU limitation caused increased proton motive force; long-term TPU limitation additionally reduced other photosynthetic components. Photosynthetic responses to CO2 can be interpreted primarily as being limited by the amount or activity of Rubisco or the capacity for ribulose bisphosphate regeneration, but at high rates of photosynthesis a third response is often seen. Photosynthesis becomes insensitive to CO2 or even declines with increasing CO2, and this behavior has been associated with a limitation of export of carbon from the Calvin-Benson cycle. It is often called the triose phosphate use (TPU) limitation. We studied the long-term consequences of this limitation using plants engineered to have reduced capacity for starch or sucrose synthesis. We studied short-term consequences using temperature as a method for changing the balance of carbon fixation capacity and TPU. A long-term and short-term TPU limitation resulted in an increase in proton motive force (PMF) in the thylakoids. Once a TPU limitation was reached, any further increases in CO2 was met with a further increase in the PMF but no increase or little increase in net assimilation of CO2. A long-term TPU limitation resulted in reduced Rubisco and RuBP regeneration capacity. We hypothesize that TPU, Rubisco activity, and RuBP regeneration are regulated so that TPU is normally in slight excess of what is required, and that this results in more effective regulation than if TPU were in large excess.
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Carbono/metabolismo , Fotosíntesis , Plantas/metabolismo , Ribulosa-Bifosfato Carboxilasa/metabolismo , Triosas/metabolismo , Dióxido de Carbono/metabolismo , Fosfatos/metabolismo , Temperatura , Tilacoides/metabolismo , TiempoRESUMEN
Isoprene emissions from poplar (Populus spp.) plantations can influence atmospheric chemistry and regional climate. These emissions respond strongly to temperature, [CO2], and drought, but the superimposed effect of these three climate change factors are, for the most part, unknown. Performing predicted climate change scenario simulations (periodic and chronic heat and drought spells [HDSs] applied under elevated [CO2]), we analyzed volatile organic compound emissions, photosynthetic performance, leaf growth, and overall carbon (C) gain of poplar genotypes emitting (IE) and nonemitting (NE) isoprene. We aimed (1) to evaluate the proposed beneficial effect of isoprene emission on plant stress mitigation and recovery capacity and (2) to estimate the cumulative net C gain under the projected future climate. During HDSs, the chloroplastidic electron transport rate of NE plants became impaired, while IE plants maintained high values similar to unstressed controls. During recovery from HDS episodes, IE plants reached higher daily net CO2 assimilation rates compared with NE genotypes. Irrespective of the genotype, plants undergoing chronic HDSs showed the lowest cumulative C gain. Under control conditions simulating ambient [CO2], the C gain was lower in the IE plants than in the NE plants. In summary, the data on the overall C gain and plant growth suggest that the beneficial function of isoprene emission in poplar might be of minor importance to mitigate predicted short-term climate extremes under elevated [CO2]. Moreover, we demonstrate that an analysis of the canopy-scale dynamics of isoprene emission and photosynthetic performance under multiple stresses is essential to understand the overall performance under proposed future conditions.
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Butadienos/análisis , Cambio Climático , Hemiterpenos/análisis , Pentanos/análisis , Populus/química , Carbono/metabolismo , Proliferación Celular , Ecosistema , Fotosíntesis , Pigmentación , Hojas de la Planta/química , Factores de Tiempo , Compuestos Orgánicos Volátiles/análisis , AguaRESUMEN
Over the last decades, post-illumination bursts (PIBs) of isoprene, acetaldehyde and green leaf volatiles (GLVs) following rapid light-to-dark transitions have been reported for a variety of different plant species. However, the mechanisms triggering their release still remain unclear. Here we measured PIBs of isoprene-emitting (IE) and isoprene non-emitting (NE) grey poplar plants grown under different climate scenarios (ambient control and three scenarios with elevated CO2 concentrations: elevated control, periodic heat and temperature stress, chronic heat and temperature stress, followed by recovery periods). PIBs of isoprene were unaffected by elevated CO2 and heat and drought stress in IE, while they were absent in NE plants. On the other hand, PIBs of acetaldehyde and also GLVs were strongly reduced in stress-affected plants of all genotypes. After recovery from stress, distinct differences in PIB emissions in both genotypes confirmed different precursor pools for acetaldehyde and GLV emissions. Changes in PIBs of GLVs, almost absent in stressed plants and enhanced after recovery, could be mainly attributed to changes in lipoxygenase activity. Our results indicate that acetaldehyde PIBs, which recovered only partly, derive from a new mechanism in which acetaldehyde is produced from methylerythritol phosphate pathway intermediates, driven by deoxyxylulose phosphate synthase activity.
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Butadienos/metabolismo , Hemiterpenos/metabolismo , Pentanos/metabolismo , Populus/metabolismo , Compuestos Orgánicos Volátiles/metabolismo , Deshidratación , Calor , Lipooxigenasa/metabolismo , Hojas de la Planta/metabolismo , Hojas de la Planta/fisiología , Hojas de la Planta/efectos de la radiación , Transpiración de Plantas/fisiología , Transpiración de Plantas/efectos de la radiación , Populus/fisiología , Populus/efectos de la radiaciónRESUMEN
AIMS/HYPOTHESIS: Glucagon-like peptide (GLP-1), an intestinal incretin produced in L cells through proglucagon processing, is released in response to meal intake. The intracellular mechanism by which L cells sense the organism energy level to coordinate the production of GLP-1 remains unclear. Mechanistic target of rapamycin (mTOR) is an intracellular fuel sensor critical for energy homeostasis. In this study, we investigated whether intestinal mTOR regulates GLP-1 production in L cells. METHODS: The effects of mTOR on GLP-1 production were examined in lean- or high-fat diet (HFD) induced diabetic C57/BL6, db/db, Neurog3-Tsc1(-/-) mice, and STC-1 cells. GLP-1 expression was investigated by real-time PCR and western blotting. Plasma GLP-1 and insulin were detected by enzyme immunoassay and radioimmunoassay, respectively. RESULTS: Fasting downregulated mTOR activity, which was associated with a decrement of intestinal proglucagon and circulating GLP-1. Upon re-feeding, these alterations returned to the levels of fed animals. In HFD induced diabetic mice, ileal mTOR signalling, proglucagon and circulating GLP-1 were significantly decreased. Inhibition of mTOR signalling by rapamycin decreased levels of intestinal and plasma GLP-1 in both normal and diabetic mice. Activation of the intestinal mTOR signalling by L-leucine or Tsc1 gene deletion increased levels of intestinal proglucagon and plasma GLP-1. Overexpression of mTOR stimulated proglucagon promoter activity and GLP-1 production, whereas inhibition of mTOR activity by overexpression of tuberous sclerosis 1 (TSC1) or TSC2 decreased proglucagon promoter activity and GLP-1 production in STC-1 cells. CONCLUSIONS/INTERPRETATION: mTOR may link energy supply with the production of GLP-1 in L cells.
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Células Enteroendocrinas/metabolismo , Péptido 1 Similar al Glucagón/metabolismo , Mucosa Intestinal/metabolismo , Serina-Treonina Quinasas TOR/metabolismo , Animales , Diabetes Mellitus Experimental/metabolismo , Dieta Alta en Grasa , Regulación hacia Abajo , Células Enteroendocrinas/efectos de los fármacos , Ayuno/metabolismo , Intestinos/efectos de los fármacos , Leucina/farmacología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proglucagón/metabolismo , Sirolimus/farmacologíaRESUMEN
Isoprene emission protects plants from a variety of abiotic stresses. It has been hypothesized to do so by partitioning into cellular membranes, particularly the thylakoid membrane. At sufficiently high concentrations, this partitioning may alter the physical properties of membranes. As much as several per cent of carbon taken up in photosynthesis is re-emitted as isoprene but the concentration of isoprene in the thylakoid membrane of rapidly emitting plants has seldom been considered. In this study, the intramembrane concentration of isoprene in phosphatidylcholine liposomes equilibrated to a physiologically relevant gas phase concentration of 20 µL L(-1) isoprene was less than predicted by ab initio calculations based on the octanol-water partitioning coefficient of isoprene while the concentration in thylakoid membranes was more. However, the concentration in both systems was roughly two orders of magnitude lower than previously assumed. High concentrations of isoprene (2000 µL L(-1) gas phase) failed to alter the viscosity of phosphatidylcholine liposomes as measured with perylene, a molecular probe of membrane structure. These results strongly suggest that the physiological concentration of isoprene within the leaves of highly emitting plants is too low to affect the dynamics of thylakoid membrane acyl lipids. It is speculated that isoprene may bind to and modulate the dynamics of thylakoid embedded proteins.
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Butadienos/química , Hemiterpenos/química , Membranas Artificiales , Pentanos/química , Hojas de la Planta/química , Spinacia oleracea/química , Tilacoides/químicaRESUMEN
INTRODUCTION: Irisin is a newly identified 112 amino acid hormone, derived as a product of fibronectin type III domain containing 5 (FNDC5), which is highly related to metabolic activity in skeletal muscle and brown fat. The effects of irisin on cardiovascular functions are unknown. PURPOSE: To explore the effects of central and peripheral irisin on cardiovascular functions. METHODS: Irisin was either administrated into 3rd ventricle of rats or intravenously, and its effects on blood pressure and cardiac contractibility measured. RESULTS: Administration of recombinant human irisin into the 3rd brain ventricle of rats activated neurons in the paraventricular nuclei of the hypothalamus. Central administration of irisin increased blood pressure and cardiac contractibility. Exogenous irisin reversed atenolol-induced inhibition of cardiac contractibility. In contrast, peripheral administration of irisin reduced blood pressure in both control and spontaneously hypertensive rats. Irisin dilated mesenteric artery rings through ATP-sensitive potassium channels. CONCLUSION: Our studies indicate that central and peripheral irisin may differentially regulate cardiovascular activities.
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Presión Sanguínea/fisiología , Fibronectinas/fisiología , Núcleo Hipotalámico Paraventricular/efectos de los fármacos , Administración Intravenosa , Animales , Presión Sanguínea/efectos de los fármacos , Fibronectinas/administración & dosificación , Fibronectinas/farmacología , Corazón/efectos de los fármacos , Corazón/fisiología , Humanos , Infusiones Intraventriculares , Canales KATP/efectos de los fármacos , Canales KATP/fisiología , Masculino , Arterias Mesentéricas/efectos de los fármacos , Arterias Mesentéricas/fisiología , Neuronas/efectos de los fármacos , Neuronas/fisiología , Núcleo Hipotalámico Paraventricular/fisiología , Ratas , Ratas Endogámicas SHR , Proteínas Recombinantes/administración & dosificación , Proteínas Recombinantes/farmacología , Vasodilatación/efectos de los fármacos , Vasodilatación/fisiologíaRESUMEN
BACKGROUND & AIMS: Ghrelin, a gut hormone with pleiotropic effects, may act as a protective signal in parenchymal cells. We investigated the protective effects of ghrelin on hepatocytes after ischaemia/reperfusion (I/R). METHODS: Hepatic injury was assessed by measurement of plasma alanine aminotransferase (ALT) and lactate dehydrogenase (LDH), histological analysis, and TUNEL assay. Effects of exogenous ghrelin and ghrelin receptor gene deletion on I/R induced injury of liver were evaluated. RESULTS: Ischaemia/reperfusion induced a profound injury to hepatocytes. This was accompanied by elevations in plasma ALT and LDH. Pretreatment with ghrelin significantly reduced elevations in plasma ALT and LDH, and attenuated tissue damage induced by hepatic I/R in mice. Hepatic injury induced by I/R was more pronounced in ghrelin receptor gene null mice. Ghrelin administration blocked the up-regulation of AMP-activated protein kinase (AMPK) activity induced by hepatic I/R. CONCLUSIONS: This study demonstrates that ghrelin contributes to the cytoprotection during hepatic I/R.
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Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Ghrelina/uso terapéutico , Hepatopatías/etiología , Hepatopatías/prevención & control , Daño por Reperfusión/complicaciones , Proteínas Quinasas Activadas por AMP/metabolismo , Alanina Transaminasa/sangre , Análisis de Varianza , Animales , Western Blotting , Eliminación de Gen , Ghrelina/farmacología , Hepatocitos/efectos de los fármacos , Etiquetado Corte-Fin in Situ , L-Lactato Deshidrogenasa/sangre , Masculino , Ratones , Ratones Endogámicos C57BL , Receptores de Ghrelina/genéticaRESUMEN
Pericytes (PCs) are located surrounding the walls of small blood vessels, particularly capillaries and microvessels. In addition to their functions in maintaining vascular integrity, participating in angiogenesis, and regulating blood flow, PCs also serve as a reservoir for multi-potent stem/progenitor cells in white, brown, beige, and bone marrow adipose tissues. Due to the complex nature of this cell population, the identification and characterization of PCs has been challenging. A comprehensive understanding of the heterogeneity of PCs may enhance their potential as therapeutic targets for metabolic syndromes or bone-related diseases. This mini-review summarizes multiple PC markers commonly employed in lineage-tracing studies, with an emphasis on their contribution to adipogenesis and functions in different adipose depots under diverse metabolic conditions.
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Adipogénesis , Pericitos , Adipogénesis/fisiología , Tejido Adiposo , Células Madre/metabolismo , CapilaresRESUMEN
Background: Extensive research on cluster headaches (CHs) has been conducted worldwide; however, there is currently no bibliometric research on CHs. Therefore, this study aimed to analyze the current research hotspots and frontiers of CHs over the past decade. Methods: Raw data on CHs was obtained from the Web of Science Core Collection database from 2014 to 2023. CiteSpace V6.2 R7 (64 bit) and Microsoft Excel were used to assess the annual publication volume, authors, countries, and references. VOSviewer 1.6.19 software was used to assess the institutions, cited authors, and keywords, and co-occurrence and clustering functions were applied to draw a visual knowledge map. Results: In the past decade, the overall annual publication volume of articles related to CHs has increased year by year, showing promising development prospects. The total 1909 articles contained six types of literature, among which the proportion of original research articles was the highest (1,270 articles, 66.53%), published in 201 journals. Cephalalgia (439 articles, 23.00%) had the highest publication volume, and the Lancet was the journal with the highest impact factor (IF = 168.9). Furthermore, the United States of America was the country with the most published papers (584 articles, 30.60%), University of London was the research institution with the most published papers (142 articles, 7.44%), and Goodsby, Peter J was found to be the most prolific author (38 articles, 1.99%). Conclusion: This study may provide some direction for subsequent researcher on CHs. The hotspots and frontiers of future research on CHs are suggested as follows: in basic medicine, more attention should be paid to pathophysiology, especially on increasing research on the pathogenesis mediated by CGRP; in clinical medicine, more attention should be paid to the design of evidence-based medicine methodology, especially the strict design, including double-blind, questionnaire, and follow-up, in randomized controlled trials, using high-quality articles for meta-analyses, and recommending high-level evidence; therapeutic techniques need to be further explored, suggesting the implementation of transcranial magnetic stimulation of the cortex, and stimulation of the sphinopalatine ganglia and occipital nerve to achieve peripheral neuromodulation. Furthermore, chronic migraine and insomnia are inextricably linked to CHs.
RESUMEN
Among central nervous system-associated malignancies, glioblastoma (GBM) is the most common and has the highest mortality rate. The high heterogeneity of GBM cell types and the complex tumor microenvironment frequently lead to tumor recurrence and sudden relapse in patients treated with temozolomide. In precision medicine, research on GBM treatment is increasingly focusing on molecular subtyping to precisely characterize the cellular and molecular heterogeneity, as well as the refractory nature of GBM toward therapy. Deep understanding of the different molecular expression patterns of GBM subtypes is critical. Researchers have recently proposed tetra fractional or tripartite methods for detecting GBM molecular subtypes. The various molecular subtypes of GBM show significant differences in gene expression patterns and biological behaviors. These subtypes also exhibit high plasticity in their regulatory pathways, oncogene expression, tumor microenvironment alterations, and differential responses to standard therapy. Herein, we summarize the current molecular typing scheme of GBM and the major molecular/genetic characteristics of each subtype. Furthermore, we review the mesenchymal transition mechanisms of GBM under various regulators.
Asunto(s)
Neoplasias Encefálicas , Glioblastoma , Fenotipo , Humanos , Glioblastoma/genética , Glioblastoma/patología , Glioblastoma/clasificación , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patología , Neoplasias Encefálicas/clasificación , Regulación Neoplásica de la Expresión Génica , Microambiente Tumoral , Transición Epitelial-Mesenquimal/genética , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismoRESUMEN
Introduction: Unlike white adipose tissue depots, bone marrow adipose tissue (BMAT) expands during caloric restriction (CR). Although mechanisms for BMAT expansion remain unclear, prior research suggested an intermediary role for increased circulating glucocorticoids. Methods: In this study, we utilized a recently described mouse model (BMAd-Cre) to exclusively target bone marrow adipocytes (BMAds) for elimination of the glucocorticoid receptor (GR) (i.e. Nr3c1) whilst maintaining GR expression in other adipose depots. Results: Mice lacking GR in BMAds (BMAd-Nr3c1 -/-) and control mice (BMAd-Nr3c1 +/+) were fed ad libitum or placed on a 30% CR diet for six weeks. On a normal chow diet, tibiae of female BMAd-Nr3c1-/- mice had slightly elevated proximal trabecular metaphyseal bone volume fraction and thickness. Both control and BMAd-Nr3c1-/- mice had increased circulating glucocorticoids and elevated numbers of BMAds in the proximal tibia following CR. However, no significant differences in trabecular and cortical bone were observed, and quantification with osmium tetroxide and µCT revealed no difference in BMAT accumulation between control or BMAd-Nr3c1 -/- mice. Differences in BMAd size were not observed between BMAd-Nr3c1-/- and control mice. Interestingly, BMAd-Nr3c1-/- mice had decreased circulating white blood cell counts 4 h into the light cycle. Discussion: In conclusion, our data suggest that eliminating GR from BMAd has minor effects on bone and hematopoiesis, and does not impair BMAT accumulation during CR.