84 research outputs found
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Wireless optogenetics protects against obesity via stimulation of non-canonical fat thermogenesis.
Cold stimuli and the subsequent activation of β-adrenergic receptor (β-AR) potently stimulate adipose tissue thermogenesis and increase whole-body energy expenditure. However, systemic activation of the β3-AR pathway inevitably increases blood pressure, a significant risk factor for cardiovascular disease, and, thus, limits its application for the treatment of obesity. To activate fat thermogenesis under tight spatiotemporal control without external stimuli, here, we report an implantable wireless optogenetic device that bypasses the β-AR pathway and triggers Ca2+ cycling selectively in adipocytes. The wireless optogenetics stimulation in the subcutaneous adipose tissue potently activates Ca2+ cycling fat thermogenesis and increases whole-body energy expenditure without cold stimuli. Significantly, the light-induced fat thermogenesis was sufficient to protect mice from diet-induced body-weight gain. The present study provides the first proof-of-concept that fat-specific cold mimetics via activating non-canonical thermogenesis protect against obesity
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Mitochondrial lipoylation integrates age-associated decline in brown fat thermogenesis.
Thermogenesis in brown adipose tissue (BAT) declines with age; however, what regulates this process remains poorly understood. Here, we identify mitochondria lipoylation as a previously unappreciated molecular hallmark of aged BAT in mice. Using mitochondrial proteomics, we show that mitochondrial lipoylation is disproportionally reduced in aged BAT through a post-transcriptional decrease in the iron-sulfur (Fe-S) cluster formation pathway. A defect in the Fe-S cluster formation by the fat-specific deletion of Bola3 significantly reduces mitochondrial lipoylation and fuel oxidation in BAT, leading to glucose intolerance and obesity. In turn, enhanced mitochondrial lipoylation by α-lipoic acid supplementation effectively restores BAT function in old mice, thereby preventing age-associated obesity and glucose intolerance. The effect of α-lipoic acids requires mitochondrial lipoylation via the Bola3 pathway and does not depend on the anti-oxidant activity of α-lipoic acid. These results open up the possibility to alleviate the age-associated decline in energy expenditure by enhancing the mitochondrial lipoylation pathway
Identification of the matricellular protein Fibulin-5 as a target molecule of glucokinase-mediated calcineurin/NFAT signaling in pancreatic islets
Glucokinase-mediated glucose signaling induces insulin secretion, proliferation, and apoptosis in pancreatic β-cells. However, the precise molecular mechanisms underlying these processes are not clearly understood. Here, we demonstrated that glucokinase activation using a glucokinase activator (GKA) significantly upregulated the expression of Fibulin-5 (Fbln5), a matricellular protein involved in matrix-cell signaling, in isolated mouse islets. The islet Fbln5 expression was induced by ambient glucose in a time- and dose-dependent manner and further enhanced by high-fat diet or the deletion of insulin receptor substrate 2 (IRS-2), whereas the GKA-induced increase in Fbln5 expression was diminished in Irs-2-deficient islets. GKA-induced Fbln5 upregulation in the islets was blunted by a glucokinase inhibitor, KATP channel opener, Ca2+ channel blocker and calcineurin inhibitor, while it was augmented by harmine, a dual-specificity tyrosine phosphorylation-regulated kinase (DYRK) 1 A inhibitor. Although deletion of Fbln5 in mice had no significant effects on the glucose tolerance or β-cell functions, adenovirus-mediated Fbln5 overexpression increased glucose-stimulated insulin secretion in INS-1 rat insulinoma cells. Since the islet Fbln5 expression is regulated through a glucokinase/KATP channel/calcineurin/nuclear factor of activated T cells (NFAT) pathway crucial for the maintenance of β-cell functions, further investigation of Fbln5 functions in the islets is warranted
DPP-4 inhibition improves early mortality, β cell function, and adipose tissue inflammation in db/db mice fed a diet containing sucrose and linoleic acid
Additional file 3: Figure S2. Liver and epididymal fat weights in db/+ mice and db/db mice. The experiments were performed in db/+ or db/db mice fed an SL diet, SO diet, SL containing DPP-4 inhibitor (0.4% des-fluoro-sitagliptin) diet, or SO containing DPP-4 inhibitor diet for 8 weeks. (left) Liver weights as a proportion of body weight (n = 5). (right) Epididymal fat weights as a proportion of body weight (n = 5)
Solitary Asymptomatic Thyroid Metastasis from Hepatocellular Carcinoma Detected by FDG-PET/CT
Thyroid metastases from hepatocellular carcinoma (HCC) seldom occur and are often difficult to diagnose because of their asymptomatic clinical course. We evaluated a very rare case of solitary thyroid metastasis from HCC that showed high uptake of fluorine-18 fluorodeoxyglucose (FDG), when imaged using fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT). The patient was a 74-year-old man and presented with a remarkably elevated des-gamma-carboxy prothrombin level of 1,157 mAU/ml 22 months after hepatic lobectomy. FDG-PET/CT imaging revealed a hypodense tumor with high FDG uptake, with a maximum standardized uptake value of 5.2 in the thyroid left lobe. Solitary thyroid metastasis from HCC was suspected and subsequent fine needle aspiration did indeed reveal HCC. The patient received left thyroidectomy with left regional lymph node dissection. Two months after left thyroidectomy, contrast-enhanced computed tomography showed local recurrence, and the patient received ongoing radiotherapy treatment. To our knowledge, the present study is the first to demonstrate the feasibility of FDG-PET/CT in the diagnosis and management of clinically diagnosed, asymptomatic, solitary thyroid metastasis from HCC
Feasibility of Intraspecific Mix Cropping in Japan-Trials with Soybean Lines in Kawatabi Field Center
Young Researchers Sessio
Thermal stress induces glycolytic beige fat formation via a myogenic state.
Environmental cues profoundly affect cellular plasticity in multicellular organisms. For instance, exercise promotes a glycolytic-to-oxidative fibre-type switch in skeletal muscle, and cold acclimation induces beige adipocyte biogenesis in adipose tissue. However, the molecular mechanisms by which physiological or pathological cues evoke developmental plasticity remain incompletely understood. Here we report a type of beige adipocyte that has a critical role in chronic cold adaptation in the absence of β-adrenergic receptor signalling. This beige fat is distinct from conventional beige fat with respect to developmental origin and regulation, and displays enhanced glucose oxidation. We therefore refer to it as glycolytic beige fat. Mechanistically, we identify GA-binding protein α as a regulator of glycolytic beige adipocyte differentiation through a myogenic intermediate. Our study reveals a non-canonical adaptive mechanism by which thermal stress induces progenitor cell plasticity and recruits a distinct form of thermogenic cell that is required for energy homeostasis and survival
BCAA catabolism in brown fat controls energy homeostasis through SLC25A44.
Branched-chain amino acid (BCAA; valine, leucine and isoleucine) supplementation is often beneficial to energy expenditure; however, increased circulating levels of BCAA are linked to obesity and diabetes. The mechanisms of this paradox remain unclear. Here we report that, on cold exposure, brown adipose tissue (BAT) actively utilizes BCAA in the mitochondria for thermogenesis and promotes systemic BCAA clearance in mice and humans. In turn, a BAT-specific defect in BCAA catabolism attenuates systemic BCAA clearance, BAT fuel oxidation and thermogenesis, leading to diet-induced obesity and glucose intolerance. Mechanistically, active BCAA catabolism in BAT is mediated by SLC25A44, which transports BCAAs into mitochondria. Our results suggest that BAT serves as a key metabolic filter that controls BCAA clearance via SLC25A44, thereby contributing to the improvement of metabolic health
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