scholarly journals The Role of PDE3B Phosphorylation in the Inhibition of Lipolysis by Insulin

2015 ◽  
Vol 35 (16) ◽  
pp. 2752-2760 ◽  
Author(s):  
Lisa M. DiPilato ◽  
Faiyaz Ahmad ◽  
Matthew Harms ◽  
Patrick Seale ◽  
Vincent Manganiello ◽  
...  
Keyword(s):  
Energy Homeostasis ◽  
Phosphorylation Site ◽  
Whole Body ◽  
Mutant Form ◽  
Brown Adipocytes ◽  
Akt Phosphorylation ◽  
Phosphodiesterase 3B ◽  
Body Energy

Inhibition of adipocyte lipolysis by insulin is important for whole-body energy homeostasis; its disruption has been implicated as contributing to the development of insulin resistance and type 2 diabetes mellitus. The main target of the antilipolytic action of insulin is believed to be phosphodiesterase 3B (PDE3B), whose phosphorylation by Akt leads to accelerated degradation of the prolipolytic second messenger cyclic AMP (cAMP). To test this hypothesis genetically, brown adipocytes lacking PDE3B were examined for their regulation of lipolysis. InPde3bknockout (KO) adipocytes, insulin was unable to suppress β-adrenergic receptor-stimulated glycerol release. Reexpressing wild-type PDE3B in KO adipocytes fully rescued the action of insulin against lipolysis. Surprisingly, a mutant form of PDE3B that ablates the major Akt phosphorylation site, murine S273, also restored the ability of insulin to suppress lipolysis. Taken together, these data suggest that phosphorylation of PDE3B by Akt is not required for insulin to suppress adipocyte lipolysis.

scholarly journals The two faces of reactive oxygen species (ROS) in adipocyte function and dysfunction

2016 ◽  
Vol 397 (8) ◽  
pp. 709-724 ◽  
Author(s):  
José Pedro Castro ◽  
Tilman Grune ◽  
Bodo Speckmann
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Animal Studies ◽  
Energy Homeostasis ◽  
Reactive Oxygen ◽  
Whole Body ◽  
Oxygen Species ◽  
Body Energy

Abstract White adipose tissue (WAT) is actively involved in the regulation of whole-body energy homeostasis via storage/release of lipids and adipokine secretion. Current research links WAT dysfunction to the development of metabolic syndrome (MetS) and type 2 diabetes (T2D). The expansion of WAT during oversupply of nutrients prevents ectopic fat accumulation and requires proper preadipocyte-to-adipocyte differentiation. An assumed link between excess levels of reactive oxygen species (ROS), WAT dysfunction and T2D has been discussed controversially. While oxidative stress conditions have conclusively been detected in WAT of T2D patients and related animal models, clinical trials with antioxidants failed to prevent T2D or to improve glucose homeostasis. Furthermore, animal studies yielded inconsistent results regarding the role of oxidative stress in the development of diabetes. Here, we discuss the contribution of ROS to the (patho)physiology of adipocyte function and differentiation, with particular emphasis on sources and nutritional modulators of adipocyte ROS and their functions in signaling mechanisms controlling adipogenesis and functions of mature fat cells. We propose a concept of ROS balance that is required for normal functioning of WAT. We explain how both excessive and diminished levels of ROS, e.g. resulting from over supplementation with antioxidants, contribute to WAT dysfunction and subsequently insulin resistance.

scholarly journals Uncoupling of sarcoendoplasmic reticulum calcium ATPase pump activity by sarcolipin as the basis for muscle non-shivering thermogenesis

2020 ◽  
Vol 375 (1793) ◽  
pp. 20190135 ◽  
Author(s):  
Naresh C. Bal ◽  
Muthu Periasamy
Keyword(s):  
Energy Homeostasis ◽  
Atp Hydrolysis ◽  
Calcium Atpase ◽  
Whole Body ◽  
Signalling Molecule ◽  
Brown Adipose ◽  
Pump Activity ◽  
Body Energy ◽  
Shivering Thermogenesis

Thermogenesis in endotherms relies on both shivering and non-shivering thermogenesis (NST). The role of brown adipose tissue (BAT) in NST is well recognized, but the role of muscle-based NST has been contested. However, recent studies have provided substantial evidence for the importance of muscle-based NST in mammals. This review focuses primarily on the role of sarcoplasmic reticulum (SR) Ca 2+ -cycling in muscle NST; specifically, it will discuss recent data showing how uncoupling of sarcoendoplasmic reticulum calcium ATPase (SERCA) (inhibition of Ca 2+ transport but not ATP hydrolysis) by sarcolipin (SLN) results in futile SERCA pump activity, increased ATP hydrolysis and heat production contributing to muscle NST. It will also critically examine how activation of muscle NST can be an important factor in regulating metabolic rate and whole-body energy homeostasis. In this regard, SLN has emerged as a powerful signalling molecule to promote mitochondrial biogenesis and oxidative metabolism in muscle. Furthermore, we will discuss the functional interplay between BAT and muscle, especially with respect to how reduced BAT function in mammals could be compensated by muscle-based NST. Based on the existing data, we argue that SLN-mediated thermogenesis is an integral part of muscle NST and that muscle NST potentially contributed to the evolution of endothermy within the vertebrate clade. This article is part of the theme issue ‘Vertebrate palaeophysiology’.

2006-P: The Role of Adipose Tissue-Resident Eosinophils in Adipocyte Metabolism and Whole-Body Energy Homeostasis

Diabetes ◽  
2019 ◽  
Vol 68 (Supplement 1) ◽  
pp. 2006-P ◽  
Author(s):  
TING LI ◽  
WILLIAM LESUER ◽  
ABHILASHA SINGH ◽  
JAMES D. HERNANDEZ ◽  
XIAODONG ZHANG ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Energy Homeostasis ◽  
Whole Body ◽  
Body Energy

scholarly journals Paracrine role for endothelial IGF-1 receptor in white adipocyte beiging

2021 ◽  
Author(s):  
Natalie J Haywood ◽  
Katherine I Bridge ◽  
Cheukyau Luk ◽  
Nele Warmke ◽  
Katie J Simmons ◽  
...  
Keyword(s):  
Potential Role ◽  
Whole Body ◽  
Environmental Cues ◽  
Brown Adipocytes ◽  
White Adipocyte ◽  
Beige Adipocytes ◽  
Close Proximity ◽  
Body Energy ◽  
Existing Form

SummaryThere are at least two distinct types of thermogenic adipocyte in mammals: a pre-existing form established during development, termed classical brown adipocytes and an inducible form, ‘beige’ adipocytes1–3. Various environmental cues can stimulate a process frequently referred to as ‘beiging’ of white adipose tissue (WAT), leading to enhanced thermogenesis and obesity resistance 4, 5. Whilst beiging of WAT as a therapeutic goal for obesity and obesity-related complications has attracted much attention6–9; therapeutics stimulating beiging without deleterious side-effects remain elusive10. The endothelium lines all blood vessels and is therefore in close proximity to all cells. Many studies support the possibility that the endothelium acts as a paracrine organ11–14. We explored the potential role of endothelial insulin-like growth factor-1 receptor (IGF-1R) as a paracrine modulator of WAT phenotype. Here we show that a reduction in endothelial IGF-1R expression in the presence of nutrient excess leads to white adipocyte beiging, increases whole-body energy expenditure and enhances insulin sensitivity via a non-cell autonomous paracrine mechanism. We demonstrate that this is mediated by endothelial release of malonic acid, which we show, using prodrug analogues, has potentially therapeutically-relevant properties in the treatment of metabolic disease.

scholarly journals Mitophagy-mediated adipose inflammation contributes to type 2 diabetes with hepatic insulin resistance

2020 ◽  
Vol 218 (3) ◽  
Author(s):  
Feng He ◽  
Yanrui Huang ◽  
Zhi Song ◽  
Huanjiao Jenny Zhou ◽  
Haifeng Zhang ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Energy Homeostasis ◽  
Hepatic Insulin Resistance ◽  
Whole Body ◽  
Ros Generation ◽  
Polyubiquitin Chains ◽  
Adipose Inflammation ◽  
Body Energy

White adipose tissues (WAT) play crucial roles in maintaining whole-body energy homeostasis, and their dysfunction can contribute to hepatic insulin resistance and type 2 diabetes mellitus (T2DM). However, the mechanisms underlying these alterations remain unknown. By analyzing the transcriptome landscape in human adipocytes based on available RNA-seq datasets from lean, obese, and T2DM patients, we reveal elevated mitochondrial reactive oxygen species (ROS) pathway and NF-κB signaling with altered fatty acid metabolism in T2DM adipocytes. Mice with adipose-specific deletion of mitochondrial redox Trx2 develop hyperglycemia, hepatic insulin resistance, and hepatic steatosis. Trx2-deficient WAT exhibited excessive mitophagy, increased inflammation, and lipolysis. Mechanistically, mitophagy was induced through increasing ROS generation and NF-κB–dependent accumulation of autophagy receptor p62/SQSTM1, which recruits damaged mitochondria with polyubiquitin chains. Importantly, administration of ROS scavenger or NF-κB inhibitor ameliorates glucose and lipid metabolic disorders and T2DM progression in mice. Taken together, this study reveals a previously unrecognized mechanism linking mitophagy-mediated adipose inflammation to T2DM with hepatic insulin resistance.

scholarly journals A-769662 inhibits adipocyte glucose uptake in an AMPK-independent manner

2021 ◽  
Vol 478 (3) ◽  
pp. 633-646
Author(s):  
Franziska Kopietz ◽  
Yazeed Alshuweishi ◽  
Silvia Bijland ◽  
Fatmah Alghamdi ◽  
Eva Degerman ◽  
...  
Keyword(s):  
Glucose Uptake ◽  
Energy Homeostasis ◽  
Inhibitory Effect ◽  
Whole Body ◽  
Ampk Activation ◽  
Independent Manner ◽  
Amp Activated Protein Kinase ◽  
Body Energy ◽  
Site Binding

Activation of AMP-activated protein kinase (AMPK) is considered a valid strategy for the treatment of type 2 diabetes. However, despite the importance of adipose tissue for whole-body energy homeostasis, the effect of AMPK activation in adipocytes has only been studied to a limited extent and mainly with the AMP-mimetic 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), which has limited specificity. The aim of this study was to evaluate the effect of the allosteric AMPK activators A-769662 and 991 on glucose uptake in adipocytes. For this purpose, primary rat or human adipocytes, and cultured 3T3-L1 adipocytes, were treated with either of the allosteric activators, or AICAR, and basal and insulin-stimulated glucose uptake was assessed. Additionally, the effect of AMPK activators on insulin-stimulated phosphorylation of Akt and Akt substrate of 160 kDa was assessed. Furthermore, primary adipocytes from ADaM site binding drug-resistant AMPKβ1 S108A knock-in mice were employed to investigate the specificity of the drugs for the observed effects. Our results show that insulin-stimulated adipocyte glucose uptake was significantly reduced by A-769662 but not 991, yet neither activator had any clear effects on basal or insulin-stimulated Akt/AS160 signaling. The use of AMPKβ1 S108A mutant-expressing adipocytes revealed that the observed inhibition of glucose uptake by A-769662 is most likely AMPK-independent, a finding which is supported by the rapid inhibitory effect A-769662 exerts on glucose uptake in 3T3-L1 adipocytes. These data suggest that AMPK activation per se does not inhibit glucose uptake in adipocytes and that the effects of AICAR and A-769662 are AMPK-independent.

Role of cell cycle regulators in adipose tissue and whole body energy homeostasis

2017 ◽  
Vol 75 (6) ◽  
pp. 975-987 ◽  
Author(s):  
I. C. Lopez-Mejia ◽  
J. Castillo-Armengol ◽  
S. Lagarrigue ◽  
L. Fajas
Keyword(s):  
Cell Cycle ◽  
Adipose Tissue ◽  
Energy Homeostasis ◽  
Whole Body ◽  
Cell Cycle Regulators ◽  
Body Energy

Exercise and MEF2–HDAC interactions

2007 ◽  
Vol 32 (5) ◽  
pp. 852-856 ◽  
Author(s):  
Sean L. McGee
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Nuclear Export ◽  
Energy Homeostasis ◽  
Whole Body ◽  
Positive Health ◽  
Exercise Induced ◽  
Amp Activated Protein Kinase ◽  
Body Energy ◽  
Skeletal Muscle Adaptations

Exercise increases the metabolic capacity of skeletal muscle, which improves whole-body energy homeostasis and contributes to the positive health benefits of exercise. This is, in part, mediated by increases in the expression of a number of metabolic enzymes, regulated largely at the level of transcription. At a molecular level, many of these genes are regulated by the class II histone deacetylase (HDAC) family of transcriptional repressors, in particular HDAC5, through their interaction with myocyte enhancer factor 2 transcription factors. HDAC5 kinases, including 5′-AMP-activated protein kinase and protein kinase D, appear to regulate skeletal muscle metabolic gene transcription by inactivating HDAC5 and inducing HDAC5 nuclear export. These mechanisms appear to participate in exercise-induced gene expression and could be important for skeletal muscle adaptations to exercise.

scholarly journals The Role of AMPK Signaling in Brown Adipose Tissue Activation

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1122
Author(s):  
Jamie I. van der van der Vaart ◽  
Mariëtte R. Boon ◽  
Riekelt H. Houtkooper
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Whole Body ◽  
Ampk Signaling ◽  
Mitochondrial Homeostasis ◽  
Brown Adipose ◽  
Metabolic Stresses ◽  
Amp Activated Protein Kinase ◽  
Body Energy

Obesity is becoming a pandemic, and its prevalence is still increasing. Considering that obesity increases the risk of developing cardiometabolic diseases, research efforts are focusing on new ways to combat obesity. Brown adipose tissue (BAT) has emerged as a possible target to achieve this for its functional role in energy expenditure by means of increasing thermogenesis. An important metabolic sensor and regulator of whole-body energy balance is AMP-activated protein kinase (AMPK), and its role in energy metabolism is evident. This review highlights the mechanisms of BAT activation and investigates how AMPK can be used as a target for BAT activation. We review compounds and other factors that are able to activate AMPK and further discuss the therapeutic use of AMPK in BAT activation. Extensive research shows that AMPK can be activated by a number of different kinases, such as LKB1, CaMKK, but also small molecules, hormones, and metabolic stresses. AMPK is able to activate BAT by inducing adipogenesis, maintaining mitochondrial homeostasis and inducing browning in white adipose tissue. We conclude that, despite encouraging results, many uncertainties should be clarified before AMPK can be posed as a target for anti-obesity treatment via BAT activation.

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