scholarly journals Rho-kinase mediates the anorexigenic action of melanocortin by suppressing AMPK

2019 ◽  
Author(s):  
Sang Soo Kim ◽  
Won Min Hwang ◽  
Won-Mo Yang ◽  
Hyon Lee ◽  
Kyong Soo Park ◽  
...  
Keyword(s):  
Food Intake ◽  
Energy Homeostasis ◽  
Rho Kinase ◽  
Metabolic Effects ◽  
Chow Diet ◽  
Physical Interaction ◽  
Signaling Mechanism ◽  
Ampk Signaling ◽  
Normal Chow

ABSTRACTObjectiveMelanocortin action is essential for the maintenance of energy homeostasis. However, knowledge of the signaling mechanism(s) that mediates the effect of melanocortin remains incomplete.MethodsROCK1 is a key regulator of energy balance in the hypothalamus. To explore the role of ROCK1 in the anorexigenic action of melanocortin, we deleted ROCK1 in MC4R neurons in mice. Next, we studied the metabolic effects of MC4R neuron-specific ROCK1-deficiency and following treatment with α-melanocyte-stimulating hormone (MSH).ResultsHere we show that α-MSH increases Rho-kinase 1 (ROCK1) activity in the hypothalamus. Deficiency of ROCK1 in MC4R-expressing neurons results in increased body weight in mice fed normal chow diet. This is likely due to increased food intake and decreased energy expenditure. Importantly, we find that ROCK1 activation in MC4R expressing neurons is required for melanocortin action, as evidenced by the fact that α– MSH’s ability to suppress food intake is impaired in MC4R neuron-specific ROCK1-deficient mice. To elucidate the mechanism by which ROCK1 mediates melanocortin action, we performedin vitrostudies in hypothalamic cells expressing MC4R. We demonstrate that α–MSH promotes the physical interaction of ROCK1 and Gα12, and this results in suppression of AMPK activity.ConclusionsOur study identifies ROCK1 as a novel mediator of melanocortin’s anorexigenic action and uncover a new MC4R→Gα12→ROCK1→AMPK signaling pathway. Targeting Rho-kinase in MC4R-expressing neurons could provide a new strategy to combat obesity and its related complications.

scholarly journals ADAR1 deficiency protects against high-fat diet-induced obesity and insulin resistance in mice

2020 ◽  
Author(s):  
Xiaobing Cui ◽  
Jia Fei ◽  
Sisi Chen ◽  
Gaylen L. Edwards ◽  
Shi-You Chen
Keyword(s):  
Insulin Resistance ◽  
Food Intake ◽  
High Fat Diet ◽  
Peptide Yy ◽  
Tolerance Test ◽  
Chow Diet ◽  
High Fat ◽  
Blood Biochemical ◽  
Insulin Tolerance ◽  
Normal Chow

Obesity is an important independent risk factor for type 2 diabetes, cardiovascular diseases, and many other chronic diseases. The objective of this study was to determine the role of adenosine deaminase acting on RNA 1 (ADAR1) in the development of obesity and insulin resistance. Wild-type (WT) and heterozygous ADAR1-deficient (Adar1+/-) mice were fed normal chow or high-fat diet (HFD) for 12 weeks. Adar1+/- mice fed with HFD exhibited a lean phenotype with reduced fat mass compared with WT controls, although no difference was found under chow diet conditions. Blood biochemical analysis and insulin tolerance test showed that Adar1+/- improved HFD-induced dyslipidemia and insulin resistance. Metabolic studies showed that food intake was decreased in Adar1+/- mice compared with the WT mice under HFD conditions. Paired feeding studies further demonstrated that Adar1+/- protected mice from HFD-induced obesity through decreased food intake. Furthermore, Adar1+/- restored the increased ghrelin expression in stomach and the decreased serum peptide YY levels under HFD conditions. These data indicate that ADAR1 may contribute to diet-induce obesity, at least partially, through modulating the ghrelin and peptide YY expression and secretion.

scholarly journals IQGAP1 binds AMPK and is required for maximum AMPK activation

2020 ◽  
pp. jbc.RA120.016193
Author(s):  
Andrew C. Hedman ◽  
Zhigang Li ◽  
Laëtitia Gorisse ◽  
Swetha Parvathaneni ◽  
Chase J. Morgan ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Intracellular Signaling ◽  
Energy Homeostasis ◽  
Molecular Mechanisms ◽  
Direct Interaction ◽  
Mitogen Activated Protein Kinase ◽  
Null Cell ◽  
Ampk Signaling ◽  
In Cells

AMP-activated protein kinase (AMPK) is a fundamental component of a protein kinase cascade that is an energy sensor. AMPK maintains energy homeostasis in the cell by promoting catabolic and inhibiting anabolic pathways. Activation of AMPK requires phosphorylation by the liver kinase B1 or by the Ca2+ /calmodulin-dependent protein kinase kinase 2 (CaMKK2). The scaffold protein IQGAP1 regulates intracellular signaling pathways, such as the mitogen-activated protein kinase and AKT signaling cascades. Recent work implicates the participation of IQGAP1 in metabolic function, but the molecular mechanisms underlying these effects are poorly understood. Here, using several approaches including binding analysis with fusion proteins, siRNA-mediated gene silencing, RT-PCR, and knockout mice, we investigated whether IQGAP1 modulates AMPK signaling. In vitro analysis reveals that IQGAP1 binds directly to the α1 subunit of AMPK. In addition, we observed a direct interaction between IQGAP1 and CaMKK2, which is mediated by the IQ domain of IQGAP1. Both CaMKK2 and AMPK associate with IQGAP1 in cells. The ability of metformin and increased intracellular free Ca2+ concentrations to activate AMPK is reduced in cells lacking IQGAP1. Importantly, Ca2+-stimulated AMPK phosphorylation was rescued by re-expression of IQGAP1 in IQGAP1-null cell lines. Comparison of the fasting response in wild-type and IQGAP1-null mice revealed that transcriptional regulation of the gluconeogenesis genes PCK1 and G6PC and the fatty acid synthesis genes FASN and ACC1 is impaired in IQGAP1-null mice. Our data disclose a previously unidentified functional interaction between IQGAP1 and AMPK and suggest that IQGAP1 modulates AMPK signaling.

scholarly journals AMP-activated protein kinase pathway and bone metabolism

2011 ◽  
Vol 212 (3) ◽  
pp. 277-290 ◽  
Author(s):  
J Jeyabalan ◽  
M Shah ◽  
B Viollet ◽  
C Chenu
Keyword(s):  
Protein Kinase ◽  
Energy Homeostasis ◽  
Bone Cells ◽  
Peripheral Tissues ◽  
Ampk Signaling ◽  
Obesity And Diabetes ◽  
Regulate Food Intake ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

There is increasing evidence that osteoporosis, similarly to obesity and diabetes, could be another disorder of energy metabolism. AMP-activated protein kinase (AMPK) has emerged over the last decade as a key sensing mechanism in the regulation of cellular energy homeostasis and is an essential mediator of the central and peripheral effects of many hormones on the metabolism of appetite, fat and glucose. Novel work demonstrates that the AMPK signaling pathway also plays a role in bone physiology. Activation of AMPK promotes bone formationin vitroand the deletion of α or β subunit of AMPK decreases bone mass in mice. Furthermore, AMPK activity in bone cells is regulated by the same hormones that regulate food intake and energy expenditure through AMPK activation in the brain and peripheral tissues. AMPK is also activated by antidiabetic drugs such as metformin and thiazolidinediones (TZDs), which also impact on skeletal metabolism. Interestingly, TZDs have detrimental skeletal side effects, causing bone loss and increasing the risk of fractures, although the role of AMPK mediation is still unclear. These data are presented in this review that also discusses the potential roles of AMPK in bone as well as the possibility for AMPK to be a future therapeutic target for intervention in osteoporosis.

scholarly journals Gpr17 deficiency in POMC neurons ameliorates the metabolic derangements caused by long-term high-fat diet feeding

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Austin M. Reilly ◽  
Shudi Zhou ◽  
Sunil K. Panigrahi ◽  
Shijun Yan ◽  
Jason M. Conley ◽  
...  
Keyword(s):  
High Fat Diet ◽  
Energy Homeostasis ◽  
Regulatory Function ◽  
Chow Diet ◽  
Dependent Manner ◽  
Metabolic Homeostasis ◽  
High Fat ◽  
Electrophysiological Properties ◽  
Insulin Tolerance ◽  
Normal Chow

Abstract Background Proopiomelanocortin (POMC) neurons in the arcuate nucleus of the hypothalamus (ARH) control energy homeostasis by sensing hormonal and nutrient cues and activating secondary melanocortin sensing neurons. We identified the expression of a G protein-coupled receptor, Gpr17, in the ARH and hypothesized that it contributes to the regulatory function of POMC neurons on metabolism. Methods In order to test this hypothesis, we generated POMC neuron-specific Gpr17 knockout (PGKO) mice and determined their energy and glucose metabolic phenotypes on normal chow diet (NCD) and high-fat diet (HFD). Results Adult PGKO mice on NCD displayed comparable body composition and metabolic features measured by indirect calorimetry. By contrast, PGKO mice on HFD demonstrated a sexually dimorphic phenotype with female PGKO mice displaying better metabolic homeostasis. Notably, female PGKO mice gained significantly less body weight and adiposity (p < 0.01), which was associated with increased energy expenditure, locomotor activity, and respiratory quotient, while males did not have an overt change in energy homeostasis. Though PGKO mice of both sexes had comparable glucose and insulin tolerance, detailed analyses of liver gene expression and serum metabolites indicate that PGKO mice could have reduced gluconeogenesis and increased lipid utilization on HFD. To elucidate the central-based mechanism(s) underlying the better-preserved energy and glucose homeostasis in PGKO mice on HFD, we examined the electrophysiological properties of POMC neurons and found Gpr17 deficiency led to increased spontaneous action potentials. Moreover, PGKO mice, especially female knockouts, had increased POMC-derived alpha-melanocyte stimulating hormone and beta-endorphin despite a comparable level of prohormone POMC in their hypothalamic extracts. Conclusions Gpr17 deficiency in POMC neurons protects metabolic homeostasis in a sex-dependent manner during dietary and aging challenges, suggesting that Gpr17 could be an effective anti-obesity target in specific populations with poor metabolic control.

scholarly journals The Metabolic Effects of Angiopoietin-like protein 8 (ANGPLT8) are Differentially Regulated by Insulin and Glucose in Adipose Tissue and Liver and are Controlled by AMPK Signaling

2019 ◽  
Author(s):  
Lu Zhang ◽  
Chris E. Shannon ◽  
Terry M. Bakewell ◽  
Muhammad A. Abdul-Ghani ◽  
Marcel Fourcaudot ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Transcriptional Control ◽  
Metabolic Effects ◽  
Luciferase Reporter ◽  
Ampk Signaling ◽  
Insulin Clamp ◽  
Metabolic Role

AbstractObjectiveThe angiopoietin-like protein (ANGPTL) family represents a promising therapeutic target for dyslipidemia, which is a feature of obesity and type 2 diabetes (T2DM). The aim of the present study was to determine the metabolic role of ANGPTL8 and to investigate its nutritional, hormonal and molecular regulation in key metabolic tissues.MethodsThe metabolism of ANGPTL8 knockout mice (ANGPTL8−/−) was examined in mice following chow and high-fat diets (HFD). The regulation of ANGPTL8 expression by insulin and glucose was quantified using a combination of in vivo insulin clamp experiments in mice and in vitro experiments in hepatocytes and adipocytes. The role of AMPK signaling was examined, and the transcriptional control of ANGPTL8 was determined using bioinformatic and luciferase reporter approaches.ResultsThe ANGPTL8−/−mice had improved glucose tolerance and displayed reduced fed and fasted plasma triglycerides. However, there was no reduction in steatosis in ANGPTL8−/−mice after the HFD. Insulin acutely activated ANGPTL8 expression in liver and adipose tissue, which was mediated by C/EBPβ. Using insulin clamp experiments we observed that glucose further enhanced ANGPTL8 expression in the presence of insulin in adipocytes only. The activation of AMPK signaling potently suppressed the effect of insulin on ANGPTL8 expression in hepatocytes.ConclusionThese data show that ANGPTL8 plays an important metabolic role in mice that may extend beyond triglyceride metabolism. The finding that insulin and glucose have distinct roles in regulating ANGPTL8 expression in liver and adipose tissue may provide important clues about the function of ANGPTL8 in these tissues.

scholarly journals Control of hyperglycemia in male mice by leflunomide: mechanisms of action

2018 ◽  
Vol 237 (1) ◽  
pp. 43-58 ◽  
Author(s):  
Junhong Chen ◽  
Jing Sun ◽  
Michelle E Doscas ◽  
Jin Ye ◽  
Ashley J Williamson ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Glucose Transporter ◽  
Chow Diet ◽  
Serine Threonine Kinase ◽  
Glucose Levels ◽  
L6 Myotubes ◽  
Insulin Tolerance ◽  
Insulin Receptor Signaling ◽  
Normal Chow

p70 S6 kinase (S6K1) is a serine/threonine kinase that phosphorylates the insulin receptor substrate-1 (IRS-1) at serine 1101 and desensitizes insulin receptor signaling. S6K1 hyperactivation due to overnutrition leads to hyperglycemia and type 2 diabetes. Our recent study showed that A77 1726, the active metabolite of the anti-rheumatoid arthritis (RA) drug leflunomide, is an inhibitor of S6K1. Whether leflunomide can control hyperglycemia and sensitize the insulin receptor has not been tested. Here we report that A77 1726 increased AKTS473/T308 and S6K1T389 phosphorylation but decreased S6S235/236 and IRS-1S1101 phosphorylation in 3T3-L1 adipocytes, C2C12 and L6 myotubes. A77 1726 increased insulin receptor tyrosine phosphorylation and binding of the p85 subunit of the PI-3 kinase to IRS-1. A77 1726 enhanced insulin-stimulated glucose uptake in L6 myotubes and 3T3-L1 adipocytes, and enhanced insulin-stimulated glucose transporter type 4 (GLUT4) translocation to the plasma membrane of L6 cells. Finally, we investigated the anti-hyperglycemic effect of leflunomide on ob/ob and high-fat diet (HFD)-induced diabetes mouse models. Leflunomide treatment normalized blood glucose levels and overcame insulin resistance in glucose and insulin tolerance tests in ob/ob and HFD-fed mice but had no effect on mice fed a normal chow diet (NCD). Leflunomide treatment increased AKTS473/T308 phosphorylation in the fat and muscle of ob/ob mice but not in normal mice. Our results suggest that leflunomide sensitizes the insulin receptor by inhibiting S6K1 activity in vitro, and that leflunomide could be potentially useful for treating patients with both RA and diabetes.

scholarly journals Propionate promotes intestinal lipolysis and metabolic benefits via AMPK/LSD1 pathway in mice

2019 ◽  
Vol 243 (3) ◽  
pp. 187-197
Author(s):  
Dan Wang ◽  
Chu-Dan Liu ◽  
Meng-Li Tian ◽  
Cheng-Quan Tan ◽  
Gang Shu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Energy Homeostasis ◽  
Short Chain Fatty Acids ◽  
Hormone Sensitive Lipase ◽  
Regulatory Control ◽  
Whole Body ◽  
Chow Diet ◽  
Microbial Fermentation ◽  
Fermentation Products

Dietary fibers and their microbial fermentation products short-chain fatty acids promote metabolic benefits, but the underlying mechanisms are still unclear. Recent studies indicate that intestinal lipid handling is under regulatory control and has broad influence on whole body energy homeostasis. Here we reported that dietary inulin and propionate significantly decreased whole body fat mass without affecting food intake in mice fed with chow diet. Meanwhile, triglyceride (TG) content was decreased and lipolysis gene expression, such as adipose triglyceride lipase (A tgl), hormone-sensitive lipase (H sl) and lysosomal acid lipase (L al) was elevated in the jejunum and ileum of inulin- and propionate-treated mice. In vitro studies on Caco-2 cells showed propionate directly induced enterocyte Atgl, Hsl and Lal gene expression and decreased TG content, via activation of phosphorylation of AMP-activated protein kinase (p-AMPK) and lysine-specific demethylase 1 (LSD1). Moreover, inulin and propionate could increase intestinal lipolysis under high-fat diet (HFD)-fed condition which contributed to the prevention of HFD-induced obesity. Our study suggests that dietary fiber inulin and its microbial fermentation product propionate can regulate metabolic homeostasis through regulating intestinal lipid handling, which may provide a novel therapeutic target for both prevention and treatment of obesity.

scholarly journals Natural Phenolic Compounds Targeting The AMPK Activation For Metabolic Health

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Khoa D.A Nguyen ◽  
Khanh V Doan ◽  
Keyword(s):  
Phenolic Compounds ◽  
Metabolic Disorders ◽  
Energy Homeostasis ◽  
Antioxidant Property ◽  
Metabolic Health ◽  
Metabolic Effects ◽  
Whole Body ◽  
Ampk Activation ◽  
Ampk Signaling ◽  
Natural Phenolic Compounds

AMP-activated protein kinase (AMPK) is a cellular energy sensor which plays a crucial role in regulation of whole-body energy homeostasis. Activation of AMPK signaling results in favorable effects on mitochondrial function, autophagy, glucose/lipid metabolism, and insulin sensitivity, making it an important therapeutic target in treatment/prevention of metabolic disorders and cancer. Recently, pharmacological studies of natural phenolic compounds indicated that the benefits on metabolic health of these phytochemicals are not only related to their protogenic antioxidant property but also to their AMPK-activating potential. Due to their diverse structures, identification of phenolic compound molecules which have potential to target the AMPK activation for beneficial metabolic effects may be promising in order to develop novel therapeutics in the prevention and/or treatment of metabolic disorders. In this minireview, we summarize beneficial metabolic outcomes of AMPK activation and discuss the capability of natural polyphenols to activate the AMPK pathway focusing on the phenolic acids as potential lead compounds.

GPR120 Regulates Pancreatic Polypeptide Secretion From Male Mouse Islets via PLC-Mediated Calcium Mobilization

Endocrinology ◽  
2020 ◽  
Vol 161 (10) ◽  
Author(s):  
Yu-Feng Zhao ◽  
Xiao-Cheng Li ◽  
Xiang-Yan Liang ◽  
Yan-Yan Zhao ◽  
Rong Xie ◽  
...  
Keyword(s):  
Pancreatic Polypeptide ◽  
Quantitative Polymerase Chain Reaction ◽  
Chow Diet ◽  
Specific Cell ◽  
Obese Mice ◽  
Normal Chow ◽  
Mouse Islets ◽  
Normal Chow Diet

Abstract The free fatty acid receptor G protein-coupled receptor 120 (GPR120) is expressed in pancreatic islets, but its specific cell distribution and function have not been fully established. In this study, a GPR120-IRES-EGFP knockin (KI) mouse was generated to identify GPR120-expressing cells with enhanced green fluorescence proteins (EGFP). EGFP-positive cells collected from KI mouse islets by flow cytometry had a significantly higher expression of pancreatic polypeptide (PP) evidenced by reverse transcriptase (RT)-quantitative polymerase chain reaction (qPCR). Single-cell RT-PCR and immunocytochemical double staining also demonstrated the coexpression of GPR120 with PP in mouse islets. The GPR120-specific agonist TUG-891 significantly increased plasma PP levels in mice. TUG-891 significantly increased PP levels in islet medium in vitro, which was markedly attenuated by GPR120 small interfering RNA treatment. TUG-891–stimulated PP secretion in islets was fully blocked by pretreatment with YM-254890 (a Gq protein inhibitor), U73122 (a phospholipase C inhibitor), or thapsigargin (an inducer of endoplasmic reticulum Ca2+ depletion), respectively. TUG-891 triggered the increase in intracellular free Ca2+ concentrations ([Ca2+]i) in PP cells, which was also eliminated by YM-254890, U73122, or thapsigargin. GPR120 gene expression was significantly reduced in islets of high-fat diet (HFD)-induced obese mice. TUG-891–stimulated PP secretion was also significantly diminished in vivo and in vitro in HFD-induced obese mice compared with that in normal-chow diet control mice. In summary, this study demonstrated that GPR120 is expressed in mouse islet PP cells and GPR120 activation stimulated PP secretion via the Gq/PLC-Ca2+ signaling pathway in normal-chow diet mice but with diminished effects in HFD-induced obese mice.

scholarly journals AMPK signaling mediates synphilin-1-induced hyperphagia and obesity in drosophila

2020 ◽  
pp. jcs.247742
Author(s):  
Jingnan Liu ◽  
Xiaobo Wang ◽  
Rui Ma ◽  
Tianxia Li ◽  
Gongbo Guo ◽  
...  
Keyword(s):  
Body Weight ◽  
Weight Gain ◽  
Food Intake ◽  
Energy Homeostasis ◽  
Body Weight Gain ◽  
Critical Role ◽  
Dominant Negative ◽  
Ampk Signaling ◽  
Ampk Phosphorylation ◽  
Transgenic Flies

Expression of synphilin-1 in neurons induces hyperphagia and obesity in a Drosophila model. However, the molecular pathways underlying synphilin-1-linked obesity remain unclear. Here, the Drosophila models and genetic tools were used to study the synphilin-1-linked pathways in energy balance by combining molecular biology and pharmacological approaches. We found that expression of human synphilin-1 in flies increased AMPK phosphorylation at Thr172 compared with non-transgenic flies. Knockdown of AMPK reduced AMPK phosphorylation and food intake in non-transgenic flies, and further suppressed synphilin-1-induced AMPK phosphorylation, hyperphagia, fat storage, and body weight gain in transgenic flies. Expression of constitutively activated AMPK significantly increased food intake and body weight gain in non-transgenic flies, but it did not alter food intake in the synphilin-1 transgenic flies. In contrast, expression of dominant-negative AMPK reduced food intake in both non-transgenic and synphilin-1 transgenic flies. Treatment with STO609 also suppressed synphilin-1-induced AMPK phosphorylation, hyperphagia and body weight gain. These results demonstrated that the AMPKsignaling pathway plays a critical role in synphilin-1-induced hyperphagia and obesity. These findings provide new insights into the mechanisms of synphilin-1 controlled energy homeostasis.

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