NCLX prevents cell death during adrenergic activation of the brown adipose tissue.
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ABSTRACT:
SUBMITTER: Assali EA
PROVIDER: S-EPMC7334226 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Increasing energy expenditure through activation of endogenous brown adipose tissue (BAT) is a potential approach to treat obesity and diabetes. The class of ?3-adrenergic receptor (AR) agonists stimulates rodent BAT, but this activity has never been demonstrated in humans. Here we determined the ability of 200 mg oral mirabegron (Myrbetriq, Astellas Pharma, Inc.), a ?3-AR agonist currently approved to treat overactive bladder, to stimulate BAT as compared to placebo. Mirabegron led to higher BAT metabolic activity as measured via (18)F-fluorodeoxyglucose ((18)F-FDG) using positron emission tomography (PET) combined with computed tomography (CT) in all twelve healthy male subjects (p = 0.001), and it increased resting metabolic rate (RMR) by 203 ± 40 kcal/day (+13%; p = 0.001). BAT metabolic activity was also a significant predictor of the changes in RMR (p = 0.006). Therefore, a ?3-AR agonist can stimulate human BAT thermogenesis and may be a promising treatment for metabolic disease.
| S-EPMC4298351 | biostudies-literature
Project description:In mammals, white adipose tissue (WAT) stores and releases lipids, whereas brown adipose tissue (BAT) oxidizes lipids to fuel thermogenesis. In obese individuals, WAT undergoes profound changes; it expands, becomes dysfunctional, and develops a low-grade inflammatory state. Importantly, BAT content and activity decline in obese subjects, mainly as a result of the conversion of brown adipocytes to white-like unilocular cells. Here, we show that BAT "whitening" is induced by multiple factors, including high ambient temperature, leptin receptor deficiency, β-adrenergic signaling impairment, and lipase deficiency, each of which is capable of inducing macrophage infiltration, brown adipocyte death, and crown-like structure (CLS) formation. Brown-to-white conversion and increased CLS formation were most marked in BAT from adipose triglyceride lipase (Atgl)-deficient mice, where, according to transmission electron microscopy, whitened brown adipocytes contained enlarged endoplasmic reticulum, cholesterol crystals, and some degenerating mitochondria, and were surrounded by an increased number of collagen fibrils. Gene expression analysis showed that BAT whitening in Atgl-deficient mice was associated to a strong inflammatory response and NLRP3 inflammasome activation. Altogether, the present findings suggest that converted enlarged brown adipocytes are highly prone to death, which, by promoting inflammation in whitened BAT, may contribute to the typical inflammatory state seen in obesity.
| S-EPMC5928436 | biostudies-literature
Project description:Although recent studies have shown that brown adipose tissue (BAT) arises from progenitor cells that also give rise to skeletal muscle, the developmental signals that control the formation of BAT remain largely unknown. Here, we show that brown preadipocytes possess primary cilia and can respond to Hedgehog (Hh) signaling. Furthermore, cell-autonomous activation of Hh signaling blocks early brown-preadipocyte differentiation, inhibits BAT formation in vivo, and results in replacement of neck BAT with poorly differentiated skeletal muscle. Finally, we show that Hh signaling inhibits BAT formation partially through up-regulation of chicken ovalbumin upstream promoter transcription factor II (COUP-TFII). Taken together, our studies uncover a previously unidentified role for Hh as an inhibitor of BAT development.
| S-EPMC4413261 | biostudies-literature
Project description:Stress-associated conditions such as psychoemotional reactivity and depression have been paradoxically linked to either weight gain or weight loss. This bi-directional effect of stress is not understood at the functional level. Here we tested the hypothesis that pre-stress level of adaptive thermogenesis and brown adipose tissue (BAT) functions explain the vulnerability or resilience to stress-induced obesity.We used wt and triple ?1,?2,?3-Adrenergic Receptors knockout (?-less) mice exposed to a model of chronic subordination stress (CSS) at either room temperature (22 °C) or murine thermoneutrality (30 °C). A combined behavioral, physiological, molecular, and immunohistochemical analysis was conducted to determine stress-induced modulation of energy balance and BAT structure and function. Immortalized brown adipocytes were used for in vitro assays.Departing from our initial observation that ?ARs are dispensable for cold-induced BAT browning, we demonstrated that under physiological conditions promoting low adaptive thermogenesis and BAT activity (e.g. thermoneutrality or genetic deletion of the ?ARs), exposure to CSS acted as a stimulus for BAT activation and thermogenesis, resulting in resistance to diet-induced obesity despite the presence of hyperphagia. Conversely, in wt mice acclimatized to room temperature, and therefore characterized by sustained BAT function, exposure to CSS increased vulnerability to obesity. Exposure to CSS enhanced the sympathetic innervation of BAT in wt acclimatized to thermoneutrality and in ?-less mice. Despite increased sympathetic innervation suggesting adrenergic-mediated browning, norepinephrine did not promote browning in ?ARs knockout brown adipocytes, which led us to identify an alternative sympathetic/brown adipocytes purinergic pathway in the BAT. This pathway is downregulated under conditions of low adaptive thermogenesis requirements, is induced by stress, and elicits activation of UCP1 in wt and ?-less brown adipocytes. Importantly, this purinergic pathway is conserved in human BAT.Our findings demonstrate that thermogenesis and BAT function are determinant of the resilience or vulnerability to stress-induced obesity. Our data support a model in which adrenergic and purinergic pathways exert complementary/synergistic functions in BAT, thus suggesting an alternative to ?ARs agonists for the activation of human BAT.
| S-EPMC4703853 | biostudies-other
Project description:BackgroundBrown adipose tissue [BAT] metabolism in vivo is vital for the development of novel strategies in combating obesity and diabetes. Currently, BAT is activated at low temperatures and measured using 2-deoxy-2-18F-fluoro-D-glucose [18F-FDG] positron-emission tomography [PET]. We report the use of β3-adrenergic receptor-mediated activation of BAT at ambient temperatures using (R, R)-5-[2-[2,3-(3-chlorphenyl)-2-hydroxyethyl-amino]propyl]-1,3-benzodioxole-2,2-dicarboxylate, disodium salt [CL316,243] (a selective β3-adrenoceptor agonist) and measured by 18F-FDG PET/computed tomography [CT].MethodsControl and CL316,243-treated (2 mg/kg) male Sprague-Dawley rats were administered with 18F-FDG for PET/CT studies and were compared to animals at cold temperatures. Receptor-blocking experiments were carried out using propranolol (5 mg/kg). Dose effects of CL316,243 were studied by injecting 0.1 to 1 mg/kg 30 min prior to 18F-FDG administration. Imaging results were confirmed by autoradiography, and histology was done to confirm BAT activation.ResultsCL316,243-activated interscapular BAT [IBAT], cervical, periaortic, and intercostal BATs were clearly visualized by PET. 18F-FDG uptake of IBAT was increased 12-fold by CL316,243 vs. 1.1-fold by cold exposure when compared to controls. 18F-FDG uptake of the CL-activated IBAT was reduced by 96.0% using intraperitoneal administration of propranolol. Average 18F-FDG uptake of IBAT increased 3.6-, 3.5-, and 7.6-fold by doses of 0.1, 0.5, and 1 mg/kg CL, respectively. Ex vivo 18F-FDG autoradiography and histology of transverse sections of IBAT confirmed intense uptake in the CL-activated group and activated IBAT visualized by PET.ConclusionOur study indicated that BAT metabolic activity could be evaluated by 18F-FDG PET using CL316,243 at ambient temperature in the rodent model. This provides a feasible and reliable method to study BAT metabolism.
| S-EPMC3250993 | biostudies-literature
Project description:Adrenergic stimulation of brown adipose tissue (BAT) induces acute and long-term responses. The acute adrenergic response activates thermogenesis by uncoupling oxidative phosphorylation and enabling increased substrate oxidation. Long-term, adrenergic signaling remodels BAT, inducing adaptive transcriptional changes that expand thermogenic capacity. Here, we show that the estrogen-related receptors alpha and gamma (ERRα, ERRγ) are collectively critical effectors of adrenergically stimulated transcriptional reprogramming of BAT. Mice lacking adipose ERRs (ERRαγAd-/-) have reduced oxidative and thermogenic capacity and rapidly become hypothermic when exposed to cold. ERRαγAd-/- mice treated long term with a β3-adrenergic agonist fail to expand oxidative or thermogenic capacity and do not increase energy expenditure in response to norepinephrine (NE). Furthermore, ERRαγAd-/- mice fed a high-fat diet do not lose weight or show improved glucose tolerance when dosed with β3-adrenergic agonists. The molecular basis of these defects is the finding that ERRs mediate the bulk of the transcriptional response to adrenergic stimulation.
| S-EPMC5993202 | biostudies-literature
Project description:ObjectiveIncreasing energy expenditure through activation of brown adipose tissue (BAT) thermogenesis is an attractive approach to counteract obesity. It is therefore essential to understand the molecular mechanisms that control BAT functions. Until now several members of the Janus kinase (JAK) - signal transducer and activator of transcription (STAT) pathway have been implicated as being relevant for BAT physiology. However, whether the STAT family member STAT5 is important for the thermogenic property of adipose tissues is unknown. Therefore, we have investigated the role of STAT5 in thermogenic fat in this paper.MethodsWe performed metabolic and molecular analyses using mice that harbor an adipocyte-specific deletion of Stat5a/b alleles.ResultsWe found that STAT5 is necessary for acute cold-induced temperature maintenance and the induction of lipid mobilization in BAT following β3-adrenergic stimulation. Moreover, mitochondrial respiration of primary differentiated brown adipocytes lacking STAT5 was diminished. Increased sensitivity to cold stress upon STAT5 deficiency was associated with reduced expression of thermogenic markers including uncoupling protein 1 (UCP1), while decreased stimulated lipolysis was linked to decreased protein kinase A (PKA) activity. Additionally, brown remodeling of white adipose tissue was diminished following chronic β3-adrenergic stimulation, which was accompanied by a decrease in mitochondrial performance.ConclusionWe conclude that STAT5 is essential for the functionality and the β-adrenergic responsiveness of thermogenic adipose tissue.
| S-EPMC7322099 | biostudies-literature
Project description:Programmed cell death-4 (PDCD4), a selective protein translation inhibitor, has shown proinflammatory effect in some inflammatory diseases, but its roles in obesity remain unestablished. This study aims to investigate the effects of PDCD4 on obesity, inflammation, and insulin resistance. Surprisingly, high-fat diet (HFD)-fed PDCD4-deficient (PDCD4(-/-)) mice exhibited an absolutely lean phenotype together with improved insulin sensitivity. Compared with wild-type obese mice, HFD-fed PDCD4(-/-) mice showed higher energy expenditure, lower epididymal fat weight, and reduced macrophage infiltration inflammatory cytokine secretion in white adipose tissue (WAT). Alleviated hepatic steatosis along with decreased plasma levels of triglyceride and cholesterol was also observed in these mice. Importantly, PDCD4 appeared to disturb lipid metabolism via inhibiting the expression of liver X receptor (LXR)-?, a master modulator of lipid homeostasis, which was elevated in HFD-fed PDCD4(-/-) mice accompanied by upregulation of its target genes and relieved endoplasmic reticulum stress in WAT. These data demonstrate that PDCD4 deficiency protects mice against diet-induced obesity, WAT inflammation, and insulin resistance through restoring the expression of LXR-?, thereby proposing PDCD4 as a potential target for treating obesity-associated diseases.
| S-EPMC3837052 | biostudies-literature
Project description:Although the accumulation of white adipose tissue (WAT) is a risk factor for disease, brown adipose tissue (BAT) has been suggested to have a protective role against obesity.We studied whether changes in BAT were related to changes in the amounts of subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) in children treated for malignancy.We examined the effect of BAT activity on weight, SAT, and VAT in 32 pediatric patients with cancer whose positron emission tomography-computed tomography (PET-CT) scans at diagnosis showed no BAT activity. Changes in weight, SAT, and VAT from diagnosis to remission for children with metabolically active BAT at disease-free follow-up (BAT+) were compared with those in children without visualized BAT when free of disease (BAT-).Follow-up PET-CT studies (4.7 ± 2.4 mo later) after successful treatment of the cancer showed BAT+ in 19 patients but no active BAT (BAT-) in 13 patients. BAT+ patients, in comparison with BAT- patients, gained significantly less weight (3.3 ± 6.6% compared with 11.0 ± 11.6%; P = 0.02) and had significantly less SAT (18.2 ± 26.5% compared with 67.4 ± 71.7%; P = 0.01) and VAT (22.6 ± 33.5% compared with 131.6 ± 171.8%; P = 0.01) during treatment. Multiple regression analysis indicated that the inverse relations between BAT activation and measures of weight, SAT, and VAT persisted even after age, glucocorticoid treatment, and the season when the PET-CT scans were obtained were accounted for.The activation of BAT in pediatric patients undergoing treatment of malignancy is associated with significantly less adipose accumulation. This trial was registered at clinicaltrials.gov as NCT01517581.
| S-EPMC3325837 | biostudies-literature
Project description:Cold exposure produces adaptive hyperplasia and growth of brown adipose tissue (BAT), the major site of non-shivering thermogenesis in rodents, associated with increased angiogenesis in this tissue. Vascular endothelial growth factor (VEGF), one of the most potent angiogenic factors, was found to be expressed abundantly in BAT of the rat. When rats were exposed to cold at 4 degrees C, the VEGF mRNA level in BAT was increased by 2-3-fold in 1-4 h, but returned to the basal level within 24 h. VEGF expression in other tissues such as heart, kidney and lung did not change after cold exposure. The cold-induced increase in VEGF mRNA was abolished by surgical sympathetic denervation, but mimicked by administration of noradrenaline or a beta3-adrenoceptor agonist CL316,243, indicating the critical role of the beta-adrenergic pathway in VEGF expression in BAT. Among three isoforms of VEGF, the mRNA of a short form (VEGF120) lacking heparin-binding activity was preferentially increased after cold exposure and treatment with the adrenergic agonists. These results suggest that cold exposure activates the sympathetic nerves and leads to a rapid increase in synthesis of VEGF in BAT, which in turn stimulates the proliferation of surrounding vascular endothelial cells.
| S-EPMC1218903 | biostudies-other