RESUMEN

Inhibition of S6 kinase 1 (S6K1) extends lifespan and improves healthspan in mice, but the underlying mechanisms are unclear. Cellular senescence is a stable growth arrest accompanied by an inflammatory senescence-associated secretory phenotype (SASP). Cellular senescence and SASP-mediated chronic inflammation contribute to age-related pathology, but the specific role of S6K1 has not been determined. Here we show that S6K1 deletion does not reduce senescence but ameliorates inflammation in aged mouse livers. Using human and mouse models of senescence, we demonstrate that reduced inflammation is a liver-intrinsic effect associated with S6K deletion. Specifically, we show that S6K1 deletion results in reduced IRF3 activation; impaired production of cytokines, such as IL1ß; and reduced immune infiltration. Using either liver-specific or myeloid-specific S6K knockout mice, we also demonstrate that reduced immune infiltration and clearance of senescent cells is a hepatocyte-intrinsic phenomenon. Overall, deletion of S6K reduces inflammation in the liver, suggesting that suppression of the inflammatory SASP by loss of S6K could underlie the beneficial effects of inhibiting this pathway on healthspan and lifespan.

RESUMEN

OBJECTIVE: Sympathetic nervous system and immune cell interactions play key roles in the regulation of metabolism. For example, recent convergent studies have shown that macrophages regulate obesity through brown adipose tissue (BAT) activation and beiging of white adipose tissue (WAT) via effects upon local catecholamine availability. However, these studies have raised issues about the underlying mechanisms involved including questions regarding the production of catecholamines by macrophages, the role of macrophage polarization state and the underlying intracellular signaling pathways in macrophages that might mediate these effects. METHODS: To address such issues we generated mice lacking Irs2, which mediates the effects of insulin and interleukin 4, specifically in LyzM expressing cells (Irs2LyzM-/- mice). RESULTS: These animals displayed obesity resistance and preservation of glucose homeostasis on high fat diet feeding due to increased energy expenditure via enhanced BAT activity and WAT beiging. Macrophages per se did not produce catecholamines but Irs2LyzM-/- mice displayed increased sympathetic nerve density and catecholamine availability in adipose tissue. Irs2-deficient macrophages displayed an anti-inflammatory transcriptional profile and alterations in genes involved in scavenging catecholamines and supporting increased sympathetic innervation. CONCLUSIONS: Our studies identify a critical macrophage signaling pathway involved in the regulation of adipose tissue sympathetic nerve function that, in turn, mediates key neuroimmune effects upon systemic metabolism. The insights gained may open therapeutic opportunities for the treatment of obesity.

Asunto(s)

Tejido Adiposo Pardo/metabolismo , Proteínas Sustrato del Receptor de Insulina/genética , Células Precursoras de Monocitos y Macrófagos/metabolismo , Obesidad/genética , Sistema Nervioso Simpático/metabolismo , Tejido Adiposo Pardo/fisiología , Animales , Catecolaminas/metabolismo , Células Cultivadas , Metabolismo Energético , Eliminación de Gen , Proteínas Sustrato del Receptor de Insulina/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Transducción de Señal , Sistema Nervioso Simpático/fisiología

RESUMEN

Feeding requires the integration of homeostatic drives with emotional states relevant to food procurement in potentially hostile environments. The ventromedial hypothalamus (VMH) regulates feeding and anxiety, but how these are controlled in a concerted manner remains unclear. Using pharmacogenetic, optogenetic, and calcium imaging approaches with a battery of behavioral assays, we demonstrate that VMH steroidogenic factor 1 (SF1) neurons constitute a nutritionally sensitive switch, modulating the competing motivations of feeding and avoidance of potentially dangerous environments. Acute alteration of SF1 neuronal activity alters food intake via changes in appetite and feeding-related behaviors, including locomotion, exploration, anxiety, and valence. In turn, intrinsic SF1 neuron activity is low during feeding and increases with both feeding termination and stress. Our findings identify SF1 neurons as a key part of the neurocircuitry that controls both feeding and related affective states, giving potential insights into the relationship between disordered eating and stress-associated psychological disorders in humans.

Asunto(s)

Ansiedad/fisiopatología , Emociones , Conducta Alimentaria , Hipotálamo/fisiología , Neuronas/fisiología , Animales , Ansiedad/metabolismo , Apetito , Calcio/metabolismo , Conducta Exploratoria , Femenino , Hipotálamo/citología , Hipotálamo/metabolismo , Locomoción , Masculino , Ratones , Neuronas/metabolismo , Factores de Empalme de ARN/genética , Factores de Empalme de ARN/metabolismo

RESUMEN

The mechanistic target of rapamycin (mTOR) signalling pathway plays a highly conserved role in aging; mice lacking ribosomal protein S6 kinase 1 (S6K1-/-) have extended lifespan and healthspan relative to wild type (WT) controls. Exactly how reduced mTOR signalling induces such effects is unclear, although preservation of stem cell function may be important. We show, using gene expression analyses, that there was a reduction in expression of cell cycle genes in young (12 week) and aged (80 week) S6K1-/- BM-derived c-Kit+ cells when compared to age-matched WT mice, suggesting that these cells are more quiescent in S6K1-/- mice. In addition, we investigated hematopoietic stem cell (HSC) frequency and function in young and aged S6K1-/-and WT mice. Young, but not aged, S6K1-/-mice had more LSK (lineage-, c-Kit+, Sca-1+) cells (% of bone marrow (BM)), including the most primitive long-term repopulating HSCs (LT-HSC) relative to WT controls. Donor-derived engraftment of LT-HSCs in recipient mice was unaffected by genotype in young mice, but was enhanced in transplants using LT-HSCs derived from aged S6K1-/- mice. Our results are the first to provide evidence that age-associated HSC functional decline is ameliorated in a long-lived mTOR mutant mouse.

Asunto(s)

Envejecimiento/genética , Células Madre Hematopoyéticas/fisiología , Proteínas Quinasas S6 Ribosómicas 90-kDa/genética , Transducción de Señal/genética , Serina-Treonina Quinasas TOR/metabolismo , Envejecimiento/metabolismo , Animales , Antígenos Ly/metabolismo , Médula Ósea/metabolismo , Femenino , Perfilación de la Expresión Génica , Trasplante de Células Madre Hematopoyéticas , Proteínas de la Membrana/metabolismo , Ratones , Proteínas Proto-Oncogénicas c-kit/metabolismo

RESUMEN

Hypothalamic ribosomal S6K1 has been suggested as a point of convergence for hormonal and nutrient signals in the regulation of feeding behavior, bodyweight, and glucose metabolism. However, the long-term effects of manipulating hypothalamic S6K1 signaling on energy homeostasis and the cellular mechanisms underlying these roles are unclear. We therefore inactivated S6K1 in pro-opiomelanocortin (POMC) and agouti-related protein (AgRP) neurons, key regulators of energy homeostasis, but in contrast to the current view, we found no evidence that S6K1 regulates food intake and bodyweight. In contrast, S6K1 signaling in POMC neurons regulated hepatic glucose production and peripheral lipid metabolism and modulated neuronal excitability. S6K1 signaling in AgRP neurons regulated skeletal muscle insulin sensitivity and was required for glucose sensing by these neurons. Our findings suggest that S6K1 signaling is not a general integrator of energy homeostasis in the mediobasal hypothalamus but has distinct roles in the regulation of glucose homeostasis by POMC and AgRP neurons.

Asunto(s)

Metabolismo Energético/fisiología , Conducta Alimentaria/fisiología , Glucosa/metabolismo , Hipotálamo/metabolismo , Neuronas/metabolismo , Proteínas Quinasas S6 Ribosómicas 90-kDa/metabolismo , Proteína Relacionada con Agouti/metabolismo , Animales , Peso Corporal/fisiología , Homeostasis/fisiología , Resistencia a la Insulina/fisiología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proopiomelanocortina/metabolismo , Transducción de Señal/fisiología

RESUMEN

Maternal obesity is linked with increased adverse pregnancy outcomes for both mother and child. The metabolic impact of excessive fat within the context of pregnancy is not fully understood. We used a mouse model of high fat (HF) feeding to induce maternal obesity to identify adipose tissue-mediated mechanisms driving metabolic dysfunction in pregnant and non-pregnant obese mice. As expected, chronic HF-feeding for 12 weeks preceding pregnancy increased peripheral (subcutaneous) and visceral (mesenteric) fat mass. However, unexpectedly at late gestation (E18.5) HF-fed mice exhibited a remarkable normalization of visceral but not peripheral adiposity, with a 53% reduction in non-pregnant visceral fat mass expressed as a proportion of body weight (P<0.001). In contrast, in control animals, pregnancy had no effect on visceral fat mass proportion. Obesity exaggerated glucose intolerance at mid-pregnancy (E14.5). However by E18.5, there were no differences, in glucose tolerance between obese and control mice. Transcriptomic analysis of visceral fat from HF-fed dams at E18.5 revealed reduced expression of genes involved in de novo lipogenesis (diacylglycerol O-acyltransferase 2--Dgat2) and inflammation (chemokine C-C motif ligand 20--Ccl2) and upregulation of estrogen receptor α (ERα) compared to HF non pregnant. Attenuation of adipose inflammation was functionally confirmed by a 45% reduction of CD11b+CD11c+ adipose tissue macrophages (expressed as a proportion of all stromal vascular fraction cells) in HF pregnant compared to HF non pregnant animals (P<0.001). An ERα selective agonist suppressed both de novo lipogenesis and expression of lipogenic genes in adipocytes in vitro. These data show that, in a HF model of maternal obesity, late gestation is associated with amelioration of visceral fat hypertrophy, inflammation and glucose intolerance, and suggest that these effects are mediated in part by elevated visceral adipocyte ERα signaling.

Asunto(s)

Adipocitos/citología , Adiposidad , Estrógenos/metabolismo , Grasa Intraabdominal/metabolismo , Ratones Obesos , Adipocitos/metabolismo , Animales , Femenino , Glucosa/metabolismo , Prueba de Tolerancia a la Glucosa , Macrófagos/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Análisis de Secuencia por Matrices de Oligonucleótidos , Embarazo , Preñez , Receptores de Estrógenos/metabolismo , Transducción de Señal , Factores de Tiempo , Transcriptoma

RESUMEN

Preterm birth (PTB) is a major public health problem, with a global prevalence of 9.6% and over a million annual neonatal deaths. In a mouse model of preterm labor (PTL) induced by intravaginal administration of a subclinical dose of lipopolysaccharide (LPS), we previously demonstrated that LPS ascends to the cervix, inducing complement activation, cervical remodeling and PTL. Here we show that complement activation also plays a role in myometrial contractions during PTL in this model. Increased levels of C5a were detected in the myometrium of LPS-treated mice but not in age-matched control or term myometrium. Human and mouse myometrium incubated with C5a showed increased frequency of contractions and expression of connexin 43, suggesting that C5a is an uterotonic molecule. Statins, which showed beneficial effects in preventing complement-mediated pregnancy complications, prevented cervical remodeling, myometrial contractions and PTL in the LPS model. The protective effects of statins in PTL were associated with increased synthesis, expression and activity of heme oxygenase (HO-1) in myometrium and cervix. Coadministration of HO-1 inhibitor tin-protoporphyrin-IX with pravastatin abrogated the protective effects of pravastatin on cervical remodeling and myometrial contractions leading to PTB. In addition, pravastatin inhibited complement activation in the cervix by increasing the synthesis and expression of complement inhibitor decay-accelerating factor. This study in mice suggests that statins might be useful to prevent PTL in humans. Clinical trials in humans are needed and if these results are confirmed, they may form the basis for a new clinical approach to prevent PTB.

Asunto(s)

Cuello del Útero/efectos de los fármacos , Complemento C5a/antagonistas & inhibidores , Inhibidores Enzimáticos/farmacología , Hemo-Oxigenasa 1/genética , Miometrio/efectos de los fármacos , Trabajo de Parto Prematuro/prevención & control , Pravastatina/farmacología , Adulto , Animales , Antígenos CD55/genética , Antígenos CD55/metabolismo , Cuello del Útero/metabolismo , Cuello del Útero/fisiopatología , Complemento C5a/farmacología , Conexina 43/genética , Conexina 43/metabolismo , Femenino , Regulación de la Expresión Génica , Hemo-Oxigenasa 1/metabolismo , Humanos , Lipopolisacáridos , Masculino , Metaloporfirinas/farmacología , Ratones , Ratones Endogámicos C57BL , Miometrio/metabolismo , Miometrio/fisiopatología , Trabajo de Parto Prematuro/inducido químicamente , Trabajo de Parto Prematuro/genética , Trabajo de Parto Prematuro/metabolismo , Embarazo , Protoporfirinas/farmacología , Contracción Uterina/efectos de los fármacos

RESUMEN

Premature babies are particularly vulnerable to brain injury. In this study we focus on cortical brain damage associated with long-term cognitive, behavioral, attentional or socialization deficits in children born preterm. Using a mouse model of preterm birth (PTB), we demonstrated that complement component C5a contributes to fetal cortical brain injury. Disruption of cortical dendritic and axonal cytoarchitecture was observed in PTB-mice. Fetuses deficient in C5aR (-/-) did not show cortical brain damage. Treatment with antibody anti-C5, that prevents generation of C5a, also prevented cortical fetal brain injury in PTB-mice. C5a also showed a detrimental effect on fetal cortical neuron development and survival in vitro. Increased glutamate release was observed in cortical neurons in culture exposed to C5a. Blockade of C5aR prevented glutamate increase and restored neurons dendritic and axonal growth and survival. Similarly, increased glutamate levels - measured by (1)HMRS - were observed in vivo in PTB-fetuses compared to age-matched controls. The blockade of glutamate receptors prevented C5a-induced abnormal growth and increased cell death in isolated fetal cortical neurons. Simvastatin and pravastatin prevented cortical fetal brain developmental and metabolic abnormalities -in vivo and in vitro. Neuroprotective effects of statins were mediated by Akt/PKB signaling pathways. This study shows that complement activation plays a crucial role in cortical fetal brain injury in PTL and suggests that complement inhibitors and statins might be good therapeutic options to improve neonatal outcomes in preterm birth.

Asunto(s)

Corteza Cerebral/metabolismo , Activación de Complemento , Complemento C5a/metabolismo , Neuronas/metabolismo , Nacimiento Prematuro/metabolismo , Animales , Anticuerpos Neutralizantes/farmacología , Células Cultivadas , Corteza Cerebral/anomalías , Corteza Cerebral/efectos de los fármacos , Complemento C5a/antagonistas & inhibidores , Complemento C5a/genética , Femenino , Feto , Regulación de la Expresión Génica , Ácido Glutámico/metabolismo , Humanos , Recién Nacido , Ratones , Modelos Animales , Neuronas/efectos de los fármacos , Neuronas/patología , Pravastatina/farmacología , Embarazo , Nacimiento Prematuro/genética , Nacimiento Prematuro/patología , Receptor de Anafilatoxina C5a/deficiencia , Receptor de Anafilatoxina C5a/genética , Receptores de Glutamato/genética , Receptores de Glutamato/metabolismo , Transducción de Señal , Simvastatina/farmacología