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Sample records for a-769662 activates ampk

  1. Bypassing AMPK Phosphorylation

    Viollet, Benoit; Foretz, Marc; Schlattner, Uwe

    2014-01-01

    AMP-activated protein kinase (AMPK) functions as a signaling hub to balance energy supply with demand. Phosphorylation of activation loop Thr172 has been considered as an essential step in AMPK activation. In this issue of Chemistry & Biology, Scott and colleagues show that the small molecule direct AMPK activator, A-769662, bypasses this phosphorylation event, and acts synergistically with AMP on naive AMPK.

  2. Belinostat-induced apoptosis and growth inhibition in pancreatic cancer cells involve activation of TAK1-AMPK signaling axis

    Wang, Bing, E-mail: wangbin69@yahoo.com; Wang, Xin-bao; Chen, Li-yu; Huang, Ling; Dong, Rui-zen

    2013-07-19

    Highlights: •Belinostat activates AMPK in cultured pancreatic cancer cells. •Activation of AMPK is important for belinostat-induced cytotoxic effects. •ROS and TAK1 are involved in belinostat-induced AMPK activation. •AMPK activation mediates mTOR inhibition by belinostat. -- Abstract: Pancreatic cancer accounts for more than 250,000 deaths worldwide each year. Recent studies have shown that belinostat, a novel pan histone deacetylases inhibitor (HDACi) induces apoptosis and growth inhibition in pancreatic cancer cells. However, the underlying mechanisms are not fully understood. In the current study, we found that AMP-activated protein kinase (AMPK) activation was required for belinostat-induced apoptosis and anti-proliferation in PANC-1 pancreatic cancer cells. A significant AMPK activation was induced by belinostat in PANC-1 cells. Inhibition of AMPK by RNAi knockdown or dominant negative (DN) mutation significantly inhibited belinostat-induced apoptosis in PANC-1 cells. Reversely, AMPK activator AICAR and A-769662 exerted strong cytotoxicity in PANC-1 cells. Belinostat promoted reactive oxygen species (ROS) production in PANC-1 cells, increased ROS induced transforming growth factor-β-activating kinase 1 (TAK1)/AMPK association to activate AMPK. Meanwhile, anti-oxidants N-Acetyl-Cysteine (NAC) and MnTBAP as well as TAK1 shRNA knockdown suppressed belinostat-induced AMPK activation and PANC-1 cell apoptosis. In conclusion, we propose that belinostat-induced apoptosis and growth inhibition require the activation of ROS-TAK1-AMPK signaling axis in cultured pancreatic cancer cells.

  3. Belinostat-induced apoptosis and growth inhibition in pancreatic cancer cells involve activation of TAK1-AMPK signaling axis

    Highlights: •Belinostat activates AMPK in cultured pancreatic cancer cells. •Activation of AMPK is important for belinostat-induced cytotoxic effects. •ROS and TAK1 are involved in belinostat-induced AMPK activation. •AMPK activation mediates mTOR inhibition by belinostat. -- Abstract: Pancreatic cancer accounts for more than 250,000 deaths worldwide each year. Recent studies have shown that belinostat, a novel pan histone deacetylases inhibitor (HDACi) induces apoptosis and growth inhibition in pancreatic cancer cells. However, the underlying mechanisms are not fully understood. In the current study, we found that AMP-activated protein kinase (AMPK) activation was required for belinostat-induced apoptosis and anti-proliferation in PANC-1 pancreatic cancer cells. A significant AMPK activation was induced by belinostat in PANC-1 cells. Inhibition of AMPK by RNAi knockdown or dominant negative (DN) mutation significantly inhibited belinostat-induced apoptosis in PANC-1 cells. Reversely, AMPK activator AICAR and A-769662 exerted strong cytotoxicity in PANC-1 cells. Belinostat promoted reactive oxygen species (ROS) production in PANC-1 cells, increased ROS induced transforming growth factor-β-activating kinase 1 (TAK1)/AMPK association to activate AMPK. Meanwhile, anti-oxidants N-Acetyl-Cysteine (NAC) and MnTBAP as well as TAK1 shRNA knockdown suppressed belinostat-induced AMPK activation and PANC-1 cell apoptosis. In conclusion, we propose that belinostat-induced apoptosis and growth inhibition require the activation of ROS-TAK1-AMPK signaling axis in cultured pancreatic cancer cells

  4. AMPK-Activated Protein Kinase Suppresses Ccr2 Expression by Inhibiting the NF-κB Pathway in RAW264.7 Macrophages

    Kumase, Fumiaki; Takeuchi, Kimio; Morizane, Yuki; Suzuki, Jun; Matsumoto, Hidetaka; Kataoka, Keiko; Al-Moujahed, Ahmad; Maidana, Daniel E.; Miller, Joan W.; Vavvas, Demetrios G.

    2016-01-01

    C-C chemokine receptor 2 (Ccr2) is a key pro-inflammatory marker of classic (M1) macrophage activation. Although Ccr2 is known to be expressed both constitutively and inductively, the full regulatory mechanism of its expression remains unclear. AMP-activated protein kinase (AMPK) is not only a master regulator of energy homeostasis but also a central regulator of inflammation. In this study, we sought to assess AMPK’s role in regulating RAW264.7 macrophage Ccr2 protein levels in resting (M0) or LPS-induced M1 states. In both M0 and M1 RAW264.7 macrophages, knockdown of the AMPKα1 subunit by siRNA led to increased Ccr2 levels whereas pharmacologic (A769662) activation of AMPK, attenuated LPS-induced increases in Ccr2 expression in an AMPK dependent fashion. The increases in Ccr2 levels by AMPK downregulation were partially reversed by NF-κB inhibition whereas TNF-a inhibition had minimal effects. Our results indicate that AMPK is a negative regulator of Ccr2 expression in RAW264.7 macrophages, and that the mechanism of action of AMPK inhibition of Ccr2 is mediated, in part, through the NF-κB pathway. PMID:26799633

  5. AMPK activators: mechanisms of action and physiological activities.

    Kim, Joungmok; Yang, Goowon; Kim, Yeji; Kim, Jin; Ha, Joohun

    2016-01-01

    AMP-activated protein kinase (AMPK) is a central regulator of energy homeostasis, which coordinates metabolic pathways and thus balances nutrient supply with energy demand. Because of the favorable physiological outcomes of AMPK activation on metabolism, AMPK has been considered to be an important therapeutic target for controlling human diseases including metabolic syndrome and cancer. Thus, activators of AMPK may have potential as novel therapeutics for these diseases. In this review, we provide a comprehensive summary of both indirect and direct AMPK activators and their modes of action in relation to the structure of AMPK. We discuss the functional differences among isoform-specific AMPK complexes and their significance regarding the development of novel AMPK activators and the potential for combining different AMPK activators in the treatment of human disease. PMID:27034026

  6. The nuclear protein Artemis promotes AMPK activation by stabilizing the LKB1-AMPK complex

    Nakagawa, Koji, E-mail: k_nakagawa@pharm.hokudai.ac.jp [Department of Pathophysiology and Therapeutics, Division of Pharmascience, Faculty of Pharmaceutical Sciences, Hokkaido University, N12 W6, Kita-ku, Sapporo, Hokkaido 060-0812 (Japan); Uehata, Yasuko; Natsuizaka, Mitsuteru; Kohara, Toshihisa; Darmanin, Stephanie [Department of Gastroenterology and Hematology, Graduate School of Medicine, Hokkaido University, N15 W7, Kita-ku, Sapporo, Hokkaido 060-8638 (Japan); Asaka, Masahiro [Department of Gastroenterology and Hematology, Graduate School of Medicine, Hokkaido University, N15 W7, Kita-ku, Sapporo, Hokkaido 060-8638 (Japan); Department of Cancer Preventive Medicine, Graduate School of Medicine, Hokkaido University, N15 W7, Kita-ku, Sapporo, Hokkaido 060-8638 (Japan); Takeda, Hiroshi [Department of Pathophysiology and Therapeutics, Division of Pharmascience, Faculty of Pharmaceutical Sciences, Hokkaido University, N12 W6, Kita-ku, Sapporo, Hokkaido 060-0812 (Japan); Department of Gastroenterology and Hematology, Graduate School of Medicine, Hokkaido University, N15 W7, Kita-ku, Sapporo, Hokkaido 060-8638 (Japan); Kobayashi, Masanobu [Department of Cancer Preventive Medicine, Graduate School of Medicine, Hokkaido University, N15 W7, Kita-ku, Sapporo, Hokkaido 060-8638 (Japan); School of Nursing and Social Services, Health Sciences University of Hokkaido, Ishikari-Toubetsu, Hokkaido 061-0293 (Japan)

    2012-11-02

    Highlights: Black-Right-Pointing-Pointer The nuclear protein Artemis physically interacts with AMPK{alpha}2. Black-Right-Pointing-Pointer Artemis co-localizes with AMPK{alpha}2 in the nucleus. Black-Right-Pointing-Pointer Artemis promotes phosphorylation and activation of AMPK. Black-Right-Pointing-Pointer The interaction between AMPK{alpha}2 and LKB1 is stabilized by Artemis. -- Abstract: AMP-activated protein kinase (AMPK) is a hetero-trimeric Ser/Thr kinase composed of a catalytic {alpha} subunit and regulatory {beta} and {gamma} subunits; it functions as an energy sensor that controls cellular energy homeostasis. In response to an increased cellular AMP/ATP ratio, AMPK is activated by phosphorylation at Thr172 in the {alpha}-subunit by upstream AMPK kinases (AMPKKs), including tumor suppressor liver kinase B1 (LKB1). To elucidate more precise molecular mechanisms of AMPK activation, we performed yeast two-hybrid screening and isolated the complementary DNA (cDNA) encoding the nuclear protein Artemis/DNA cross-link repair 1C (DCLRE1C) as an AMPK{alpha}2-binding protein. Artemis was found to co-immunoprecipitate with AMPK{alpha}2, and the co-localization of Artemis with AMPK{alpha}2 in the nucleus was confirmed by immunofluorescence staining in U2OS cells. Moreover, over-expression of Artemis enhanced the phosphorylation of AMPK{alpha}2 and the AMPK substrate acetyl-CoA carboxylase (ACC). Conversely, RNAi-mediated knockdown of Artemis reduced AMPK and ACC phosphorylation. In addition, Artemis markedly increased the physical association between AMPK{alpha}2 and LKB1. Taken together, these results suggest that Artemis functions as a positive regulator of AMPK signaling by stabilizing the LKB1-AMPK complex.

  7. AMPK Activation Affects Glutamate Metabolism in Astrocytes

    Voss, Caroline Marie; Pajęcka, Kamilla; Stridh, Malin H;

    2015-01-01

    acid (TCA) cycle was studied using high-performance liquid chromatography analysis supplemented with gas chromatography-mass spectrometry technology. It was found that AMPK activation had profound effects on the pathways involved in glutamate metabolism since the entrance of the glutamate carbon...... affected by a reduction of the flux of glutamate derived carbon through the malic enzyme and pyruvate carboxylase catalyzed reactions. Finally, it was found that in the presence of glutamate as an additional substrate, glucose metabolism monitored by the use of tritiated deoxyglucose was unaffected by AMPK...

  8. Activation of AMPK and its Impact on Exercise Capacity.

    Niederberger, Ellen; King, Tanya S; Russe, Otto Quintus; Geisslinger, Gerd

    2015-11-01

    Activation of the adenosine monophosphate (AMP)-activated kinase (AMPK) contributes to beneficial effects such as improvement of the hyperglycemic state in diabetes as well as reduction of obesity and inflammatory processes. Furthermore, stimulation of AMPK activity has been associated with increased exercise capacity. A study published in 2008, directly before the Olympic Games in Beijing, showed that the AMPK activator AICAR (5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide) increased the running capacity of mice without any training and thus, prompted the World Anti-Doping Agency (WADA) to include certain AMPK activators in the list of forbidden drugs. This raises the question as to whether all AMPK activators should be considered for registration or whether the increase in exercise performance is only associated with specific AMPK-activating substances. In this review, we intend to shed light on currently published AMPK-activating drugs, their working mechanisms, and their impact on body fitness. PMID:26186961

  9. How is AMPK activity regulated in skeletal muscles during exercise?

    Jørgensen, Sebastian Beck; Rose, Adam John

    2008-01-01

    AMPK is a metabolic "master" controller activated in skeletal muscle by exercise in a time and intensity dependent manner, and has been implicated in regulating metabolic pathways in muscle during physical exercise. AMPK signaling in skeletal muscle is regulated by several systemic...... and intracellular factors and the regulation of skeletal muscle AMPK in response to exercise is the focus of this review. Specifically, the role of LKB1 and phosphatase PP2C in nucleotide-dependent activation of AMPK, and ionized calcium in CaMKK-dependent activation of AMPK in working muscle is discussed. We also...

  10. Arctigenin alleviates ER stress via activating AMPK

    Yuan GU; Xiao-xiao SUN; Ji-ming YE; Li HE; Shou-sheng YAN; Hao-hao ZHANG; Li-hong HU; Jun-ying YUAN; Qiang YU

    2012-01-01

    Aim:To investigate the protective effects of arctigenin (ATG),a phenylpropanoid dibenzylbutyrolactone lignan from Arctium lappa L (Compositae),against ER stress in vitro and the underlying mechanisms.Methods:A cell-based screening assay for ER stress regulators was established.Cell viability was measured using MTT assay.PCR and Western blotting were used to analyze gene and protein expression.Silencing of the CaMKKβ,LKB1,and AMPKα1 genes was achieved by RNA interference (RNAi).An ATP bioluminescent assay kit was employed to measure the intracellular ATP levels.Results:ATG (2.5,5,and 10 μmol/L) inhibited cell death and unfolded protein response (UPR) in a concentration-dependent manner in cells treated with the ER stress inducer brefeldin A (100 nmol/L).ATG (1,5,and 10 μmol/L) significantly attenuated protein synthesis in cells through inhibiting mTOR-p7OS6K signaling and eEF2 activity,which were partially reversed by silencing AMPKα1 with RNAi.ATG (1-50 μmol/L) reduced intracellular ATP level and activated AMPK through inhibiting complex I-mediated respiration.Pretreatment of cells with the AMPK inhibitor compound C (25 μmol/L) rescued the inhibitory effects of ATG on ER stress.Furthermore,ATG (2.5 and 5μmol/L) efficiently activated AMPK and reduced the ER stress and cell death induced by palmitate (2 mmol/L) in INS-1 β cells.Conclusion:ATG is an effective ER stress alleviator,which protects cells against ER stress through activating AMPK,thus attenuating protein translation and reducing ER load.

  11. The nuclear protein Artemis promotes AMPK activation by stabilizing the LKB1–AMPK complex

    Highlights: ► The nuclear protein Artemis physically interacts with AMPKα2. ► Artemis co-localizes with AMPKα2 in the nucleus. ► Artemis promotes phosphorylation and activation of AMPK. ► The interaction between AMPKα2 and LKB1 is stabilized by Artemis. -- Abstract: AMP-activated protein kinase (AMPK) is a hetero-trimeric Ser/Thr kinase composed of a catalytic α subunit and regulatory β and γ subunits; it functions as an energy sensor that controls cellular energy homeostasis. In response to an increased cellular AMP/ATP ratio, AMPK is activated by phosphorylation at Thr172 in the α-subunit by upstream AMPK kinases (AMPKKs), including tumor suppressor liver kinase B1 (LKB1). To elucidate more precise molecular mechanisms of AMPK activation, we performed yeast two-hybrid screening and isolated the complementary DNA (cDNA) encoding the nuclear protein Artemis/DNA cross-link repair 1C (DCLRE1C) as an AMPKα2-binding protein. Artemis was found to co-immunoprecipitate with AMPKα2, and the co-localization of Artemis with AMPKα2 in the nucleus was confirmed by immunofluorescence staining in U2OS cells. Moreover, over-expression of Artemis enhanced the phosphorylation of AMPKα2 and the AMPK substrate acetyl-CoA carboxylase (ACC). Conversely, RNAi-mediated knockdown of Artemis reduced AMPK and ACC phosphorylation. In addition, Artemis markedly increased the physical association between AMPKα2 and LKB1. Taken together, these results suggest that Artemis functions as a positive regulator of AMPK signaling by stabilizing the LKB1–AMPK complex.

  12. Exercise-induced AMPK activity in skeletal muscle

    Friedrichsen, Martin; Mortensen, Brynjulf; Pehmøller, Christian;

    2013-01-01

    The energy/fuel sensor 5'-AMP-activated protein kinase (AMPK) is viewed as a master regulator of cellular energy balance due to its many roles in glucose, lipid, and protein metabolism. In this review we focus on the regulation of AMPK activity in skeletal muscle and its involvement in glucose...... metabolism, including glucose transport and glycogen synthesis. In addition, we discuss the plausible interplay between AMPK and insulin signaling regulating these processes....

  13. Activation of AMP-activated kinase modulates sensitivity of glioma cells against epidermal growth factor receptor inhibition.

    Hartel, Ines; Ronellenfitsch, Michael; Wanka, Christina; Wolking, Stefan; Steinbach, Joachim P; Rieger, Johannes

    2016-07-01

    The epidermal growth factor (EGFR) pathway is frequently activated in glioblastoma but the clinical efficacy of EGFR inhibitors in malignant glioma has been disappointing. The reasons for the failure of the mechanisms of resistance of these inhibitors are unclear, but may involve factors of the tumor microenvironment such as limited glucose availability and hypoxia. It was therefore examined whether glucose and oxygen influenced the response of glioma cells to EGFR inhibition. Decreased levels of glucose and oxygen led to resistance against the EGFR inhibitor PD153035, whereas high glucose amounts and normoxia sensitised glioma cells towards the inhibitor. Low levels of glucose and oxygen stimulated AMP-activated kinase (AMPK) in glioma cells. 2DG, an inhibitor of glycolysis, and the AMPK activator A769662 reduced glucose consumption, induced phosphorylation of AMPK and mimicked the effects of low glucose availability on the toxicity of PD153035. Similarly, 2DG reduced toxicity of imatinib in K562 leukemia cells. In contrast, inhibition of AMPK by compound C or by short-hairpin (sh)-mediated gene suppression increased cell death induced by the EGFR inhibitor and reverted the protective effects of 2DG and A769662. In conclusion, cytotoxicity of EGFR inhibition can be diminished by AMPK activation in glioma cells. These results may provide one explanation for the low activity of EGFR inhibitors in clinical trials and suggest antagonism of AMPK or of AMPK-regulated metabolic alterations as a promising approach to enhance their therapeutic efficacy. PMID:27121290

  14. Discovery of Pyridones As Oral AMPK Direct Activators.

    Mirguet, Olivier; Sautet, Stéphane; Clément, Catherine-Anne; Toum, Jérôme; Donche, Frédéric; Marques, Celine; Rondet, Emilie; Pizzonero, Mathieu; Beaufils, Benjamin; Dudit, Yann; Huet, Pascal; Trottet, Lionel; Grondin, Pascal; Brusq, Jean-Marie; Boursier, Eric; Saintillan, Yannick; Nicodeme, Edwige

    2013-07-11

    AMP-activated protein kinase (AMPK) is an evolutionarily conserved fuel-sensing enzyme that is activated in shortage of energy and suppressed in its surfeit. AMPK activation stimulates fatty acid oxidation, enhances insulin sensitivity, alleviates hyperglycemia and hyperlipidemia, and inhibits proinflammatory changes. Thus, AMPK is a well-received therapeutic target for type 2 diabetes and other metabolic disorders. Here, we will report the discovery of pyrrolopyridone derivatives as AMPK direct activators. We will illustrate the synthesis and structure-activity relationships of the series as well as some pharmacokinetic results. Some compounds exhibited encouraging oral exposure and were evaluated in a mouse diabetic model. Compound 17 showed oral activity at 30 mg/kg on blood glucose. PMID:24900722

  15. Pharmacologic regulation of AMPK in breast cancer affects cytoskeletal properties involved with microtentacle formation and re-attachment.

    Chakrabarti, Kristi R; Whipple, Rebecca A; Boggs, Amanda E; Hessler, Lindsay K; Bhandary, Lekhana; Vitolo, Michele I; Thompson, Keyata; Martin, Stuart S

    2015-11-01

    The presence of tumor cells in the circulation is associated with a higher risk of metastasis in patients with breast cancer. Circulating breast tumor cells use tubulin-based structures known as microtentacles (McTNs) to re-attach to endothelial cells and arrest in distant organs. McTN formation is dependent on the opposing cytoskeletal forces of stable microtubules and the actin network. AMP-activated protein kinase (AMPK) is a cellular metabolic regulator that can alter actin and microtubule organization in epithelial cells. We report that AMPK can regulate the cytoskeleton of breast cancer cells in both attached and suspended conditions. We tested the effects of AMPK on microtubule stability and the actin-severing protein, cofilin. AMPK inhibition with compound c increased both microtubule stability and cofilin activation, which also resulted in higher McTN formation and re-attachment. Conversely, AMPK activation with A-769662 decreased microtubule stability and cofilin activation with concurrent decreases in McTN formation and cell re-attachment. This data shows for the first time that AMPK shifts the balance of cytoskeletal forces in suspended breast cancer cells, which affect their ability to form McTNs and re-attach. These results support a model where AMPK activators may be used therapeutically to reduce the metastatic efficiency of breast tumor cells. PMID:26431377

  16. Transitory activation of AMPK at reperfusion protects the ischaemic-reperfused rat myocardium against infarction

    Paiva, MA; Gonçalves, L.; Providência, LA; Davidson, SM; Yellon, DM; Mocanu, MM

    2010-01-01

    PURPOSE: AMPK plays a crucial role in the regulation of the energy metabolism of the heart. During ischaemia, AMPK activation is a known adaptative prosurvival mechanism that helps to maintain the energy levels of the myocardium. However, it still remains unclear if activation of AMPK during reperfusion is beneficial for the heart. Two known AMPK activators (metformin and AICAR) were used to verify the hypothesis that a transitory activation of AMPK at reperfusion may exert cardioprotection, ...

  17. Cordycepin activates AMP-activated protein kinase (AMPK) via interaction with the γ1 subunit

    Wu, Chongming; Guo, Yanshen; Su, Yan; Zhang, Xue; Luan, Hong; Zhang, Xiaopo; Zhu, Huixin; He, Huixia; Wang, Xiaoliang; Sun, Guibo; Sun, Xiaobo; Guo, Peng; Zhu, Ping

    2013-01-01

    Cordycepin is a bioactive component of the fungus Cordyceps militaris. Previously, we showed that cordycepin can alleviate hyperlipidemia through enhancing the phosphorylation of AMP-activated protein kinase (AMPK), but the mechanism of this stimulation is unknown. Here, we investigated the potential mechanisms of cordycepin-induced AMPK activation in HepG2 cells. Treatment with cordycepin largely reduced oleic acid (OA)-elicited intracellular lipid accumulation and increased AMPK activity in...

  18. AMP-activated protein kinase (AMPK) activation regulates in vitro bone formation and bone mass.

    Shah, M; Kola, B; Bataveljic, A; Arnett, T R; Viollet, B; Saxon, L; Korbonits, M; Chenu, C

    2010-08-01

    Adenosine 5'-monophosphate-activated protein kinase (AMPK), a regulator of energy homeostasis, has a central role in mediating the appetite-modulating and metabolic effects of many hormones and antidiabetic drugs metformin and glitazones. The objective of this study was to determine if AMPK can be activated in osteoblasts by known AMPK modulators and if AMPK activity is involved in osteoblast function in vitro and regulation of bone mass in vivo. ROS 17/2.8 rat osteoblast-like cells were cultured in the presence of AMPK activators (AICAR and metformin), AMPK inhibitor (compound C), the gastric peptide hormone ghrelin and the beta-adrenergic blocker propranolol. AMPK activity was measured in cell lysates by a functional kinase assay and AMPK protein phosphorylation was studied by Western Blotting using an antibody recognizing AMPK Thr-172 residue. We demonstrated that treatment of ROS 17/2.8 cells with AICAR and metformin stimulates Thr-172 phosphorylation of AMPK and dose-dependently increases its activity. In contrast, treatment of ROS 17/2.8 cells with compound C inhibited AMPK phosphorylation. Ghrelin and propranolol dose-dependently increased AMPK phosphorylation and activity. Cell proliferation and alkaline phosphatase activity were not affected by metformin treatment while AICAR significantly inhibited ROS 17/2.8 cell proliferation and alkaline phosphatase activity at high concentrations. To study the effect of AMPK activation on bone formation in vitro, primary osteoblasts obtained from rat calvaria were cultured for 14-17days in the presence of AICAR, metformin and compound C. Formation of 'trabecular-shaped' bone nodules was evaluated following alizarin red staining. We demonstrated that both AICAR and metformin dose-dependently increase trabecular bone nodule formation, while compound C inhibits bone formation. When primary osteoblasts were co-treated with AICAR and compound C, compound C suppressed the stimulatory effect of AICAR on bone nodule formation

  19. AMP-activated protein kinase (AMPK) activation regulates in vitro bone formation and bone mass

    Shah, M; Kola, B; Bataveljic, A.; Arnett, T. R.; Viollet, B.; Saxon, L.; Korbonits, M.; C. Chenu

    2010-01-01

    Adenosine 5′-monophosphate-activated protein kinase (AMPK), a regulator of energy homeostasis, has a central role in mediating the appetite-modulating and metabolic effects of many hormones and antidiabetic drugs metformin and glitazones. The objective of this study was to determine if AMPK can be activated in osteoblasts by known AMPK modulators and if AMPK activity is involved in osteoblast function in vitro and regulation of bone mass in vivo. ROS 17/2.8 rat osteoblast-like cells were cult...

  20. Sex-Specific Regulation of AMP-Activated Protein Kinase (AMPK) in the Pacific Oyster Crassostrea gigas

    Guevelou, Eric; Huvet, Arnaud; Galindo-sanchez, Clara E.; Milan, Massimo; Quillien, Virgile; Daniel, Jean-yves; Quere, Claudie; Boudry, Pierre; Corporeau, Charlotte

    2013-01-01

    The hermaphrodite Pacific oyster Crassostrea gigas displays a high energy allocation to reproduction. We studied the expression of AMP-activated protein kinase (AMPK) during gametogenesis in the gonad and characterized the mRNA sequences of the AMPK subunits: the AMPK alpha mRNA sequence was previously characterized; we identified AMPK beta, AMPK gamma, and mRNAs of putative AMPK-related targets following bioinformatics mining on existing genomic resources. We analyzed the mRNA expression of ...

  1. Activated AMPK inhibits PPAR-{alpha} and PPAR-{gamma} transcriptional activity in hepatoma cells.

    Sozio, Margaret S; Lu, Changyue; Zeng, Yan; Liangpunsakul, Suthat; Crabb, David W

    2011-10-01

    AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor-α (PPAR-α) are critical regulators of short-term and long-term fatty acid oxidation, respectively. We examined whether the activities of these molecules were coordinately regulated. H4IIEC3 cells were transfected with PPAR-α and PPAR-γ expression plasmids and a peroxisome-proliferator-response element (PPRE) luciferase reporter plasmid. The cells were treated with PPAR agonists (WY-14,643 and rosiglitazone), AMPK activators 5-aminoimidazole-4-carboxamide riboside (AICAR) and metformin, and the AMPK inhibitor compound C. Both AICAR and metformin decreased basal and WY-14,643-stimulated PPAR-α activity; compound C increased agonist-stimulated reporter activity and partially reversed the effect of the AMPK activators. Similar effects on PPAR-γ were seen, with both AICAR and metformin inhibiting PPRE reporter activity. Compound C increased basal PPAR-γ activity and rosiglitazone-stimulated activity. In contrast, retinoic acid receptor-α (RAR-α), another nuclear receptor that dimerizes with retinoid X receptor (RXR), was largely unaffected by the AMPK activators. Compound C modestly increased AM580 (an RAR agonist)-stimulated activity. The AMPK activators did not affect PPAR-α binding to DNA, and there was no consistent correlation between effects of the AMPK activators and inhibitor on PPAR and the nuclear localization of AMPK-α subunits. Expression of either a constitutively active or dominant negative AMPK-α inhibited basal and WY-14,643-stimulated PPAR-α activity and basal and rosiglitazone-stimulated PPAR-γ activity. We concluded that the AMPK activators AICAR and metformin inhibited transcriptional activities of PPAR-α and PPAR-γ, whereas inhibition of AMPK with compound C activated both PPARs. The effects of AMPK do not appear to be mediated through effects on RXR or on PPAR/RXR binding to DNA. These effects are independent of kinase activity and instead appear to

  2. Protective effect of nectandrin B, a potent AMPK activator on neointima formation: inhibition of Pin1 expression through AMPK activation

    Ki, Sung Hwan; Lee, Jung-Woon; Lim, Sung Chul; Hien, Tran Thi; Im, Ji Hye; Oh, Won Keun; Lee, Moo Yeol; Ji, Young Hyun; Kim, Yoon Gyoon; Kang, Keon Wook

    2013-01-01

    Background and Purpose Neointima is considered a critical event in the development of vascular occlusive disease. Nectandrin B from nutmeg functions as a potent AMP-activated protein kinase (AMPK) activators. The present study addressed whether nectandrin B inhibits intimal hyperplasia in guide wire-injured arteries and examined its molecular mechanism. Experimental Approach Neointima was induced by guide wire injury in mouse femoral arteries. Cell proliferation and mechanism studies were performed in rat vascular smooth muscle cells (VSMC) culture model. Key Results Nectandrin B increased AMPK activity in VSMC. Nectandrin B inhibited the cell proliferation induced by PDGF and DNA synthesis. Moreover, treatment of nectandrin B suppressed neointima formation in femoral artery after guide wire injury. We have recently shown that Pin1 plays a critical role in VSMC proliferation and neointima formation. Nectandrin B potently blocked PDGF-induced Pin1 and cyclin D1 expression and nectandrin B‘s anti-proliferation effect was diminished in Pin1 overexpressed VSMC. PDGF-induced phosphorylation of ERK and Akt was marginally affected by nectandrin B. However, nectandrin B increased the levels of p53 and its downstream target p21 and, also reversibly decreased the expression of E2F1 and phosphorylated Rb in PDGF-treated VSMC. AMPK inhibition by dominant mutant form of adenovirus rescued nectandrin B-mediated down-regulation of Pin1 and E2F1. Conclusions and Implications Nectandrin B inhibited VSMC proliferation and neointima formation via inhibition of E2F1-dependent Pin1 gene transcription, which is mediated through the activation of an AMPK/p53-triggered pathway. PMID:23004677

  3. Cordycepin activates AMP-activated protein kinase (AMPK) via interaction with the γ1 subunit

    Wu, Chongming; Guo, Yanshen; Su, Yan; Zhang, Xue; Luan, Hong; Zhang, Xiaopo; Zhu, Huixin; He, Huixia; Wang, Xiaoliang; Sun, Guibo; Sun, Xiaobo; Guo, Peng; Zhu, Ping

    2014-01-01

    Cordycepin is a bioactive component of the fungus Cordyceps militaris. Previously, we showed that cordycepin can alleviate hyperlipidemia through enhancing the phosphorylation of AMP-activated protein kinase (AMPK), but the mechanism of this stimulation is unknown. Here, we investigated the potential mechanisms of cordycepin-induced AMPK activation in HepG2 cells. Treatment with cordycepin largely reduced oleic acid (OA)-elicited intracellular lipid accumulation and increased AMPK activity in a dose-dependent manner. Cordycepin-induced AMPK activation was not accompanied by changes in either the intracellular levels of AMP or the AMP/ATP ratio, nor was it influenced by calmodulin-dependent protein kinase kinase (CaMKK) inhibition; however, this activation was significantly suppressed by liver kinase B1 (LKB1) knockdown. Molecular docking, fluorescent and circular dichroism measurements showed that cordycepin interacted with the γ1 subunit of AMPK. Knockdown of AMPKγ1 by siRNA substantially abolished the effects of cordycepin on AMPK activation and lipid regulation. The modulating effects of cordycepin on the mRNA levels of key lipid regulatory genes were also largely reversed when AMPKγ1 expression was inhibited. Together, these data suggest that cordycepin may inhibit intracellular lipid accumulation through activation of AMPK via interaction with the γ1 subunit. PMID:24286368

  4. Novel small-molecule AMPK activator orally exerts beneficial effects on diabetic db/db mice

    Li, Yuan-Yuan; Yu, Li-Fang; Zhang, Li-Na; Qiu, Bei-Ying; Su, Ming-Bo; Wu, Fang; Chen, Da-Kai; Pang, Tao; Gu, Min; Zhang, Wei; Ma, Wei-Ping; Jiang, Hao-Wen; Li, Jing-Ya, E-mail: jyli@mail.shcnc.ac.cn; Nan, Fa-Jun, E-mail: fjnan@mail.shcnc.ac.cn; Li, Jia, E-mail: jli@mail.shcnc.ac.cn

    2013-12-01

    AMP-activated protein kinase (AMPK), which is a pivotal guardian of whole-body energy metabolism, has become an attractive therapeutic target for metabolic syndrome. Previously, using a homogeneous scintillation proximity assay, we identified the small-molecule AMPK activator C24 from an optimization based on the original allosteric activator PT1. In this paper, the AMPK activation mechanism of C24 and its potential beneficial effects on glucose and lipid metabolism on db/db mice were investigated. C24 allosterically stimulated inactive AMPK α subunit truncations and activated AMPK heterotrimers by antagonizing autoinhibition. In primary hepatocytes, C24 increased the phosphorylation of AMPK downstream target acetyl-CoA carboxylase dose-dependently without changing intracellular AMP/ATP ratio, indicating its allosteric activation in cells. Through activating AMPK, C24 decreased glucose output by down-regulating mRNA levels of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) in primary hepatocytes. C24 also decreased the triglyceride and cholesterol contents in HepG2 cells. Due to its improved bioavailability, chronic oral treatment with multiple doses of C24 significantly reduced blood glucose and lipid levels in plasma, and improved the glucose tolerance of diabetic db/db mice. The hepatic transcriptional levels of PEPCK and G6Pase were reduced. These results demonstrate that this orally effective activator of AMPK represents a novel approach to the treatment of metabolic syndrome. - Highlights: • C24 activates AMPK through antagonizing autoinhibition within α subunit. • C24 activates AMPK in hepatocytes and decreases glucose output via AMPK. • C24 exerts beneficial effects on diabetic db/db mice. • C24 represents a novel therapeutic for treatment of metabolic syndrome.

  5. Novel small-molecule AMPK activator orally exerts beneficial effects on diabetic db/db mice

    AMP-activated protein kinase (AMPK), which is a pivotal guardian of whole-body energy metabolism, has become an attractive therapeutic target for metabolic syndrome. Previously, using a homogeneous scintillation proximity assay, we identified the small-molecule AMPK activator C24 from an optimization based on the original allosteric activator PT1. In this paper, the AMPK activation mechanism of C24 and its potential beneficial effects on glucose and lipid metabolism on db/db mice were investigated. C24 allosterically stimulated inactive AMPK α subunit truncations and activated AMPK heterotrimers by antagonizing autoinhibition. In primary hepatocytes, C24 increased the phosphorylation of AMPK downstream target acetyl-CoA carboxylase dose-dependently without changing intracellular AMP/ATP ratio, indicating its allosteric activation in cells. Through activating AMPK, C24 decreased glucose output by down-regulating mRNA levels of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) in primary hepatocytes. C24 also decreased the triglyceride and cholesterol contents in HepG2 cells. Due to its improved bioavailability, chronic oral treatment with multiple doses of C24 significantly reduced blood glucose and lipid levels in plasma, and improved the glucose tolerance of diabetic db/db mice. The hepatic transcriptional levels of PEPCK and G6Pase were reduced. These results demonstrate that this orally effective activator of AMPK represents a novel approach to the treatment of metabolic syndrome. - Highlights: • C24 activates AMPK through antagonizing autoinhibition within α subunit. • C24 activates AMPK in hepatocytes and decreases glucose output via AMPK. • C24 exerts beneficial effects on diabetic db/db mice. • C24 represents a novel therapeutic for treatment of metabolic syndrome

  6. Synthesis and biological evaluation of arctigenin ester and ether derivatives as activators of AMPK.

    Shen, Sida; Zhuang, Jingjing; Chen, Yijia; Lei, Min; Chen, Jing; Shen, Xu; Hu, Lihong

    2013-07-01

    A series of new arctigenin and 9-deoxy-arctigenin derivatives bearing different ester and ether side chains at the phenolic hydroxyl positions are designed, synthesized, and evaluated for activating AMPK potency in L6 myoblasts. Initial biological evaluation indicates that some alkyl ester and phenethyl ether arctigenin derivatives display potential activities in AMPK phosphorylation improvement. Further structure-activity relationship analysis shows that arctigenin ester derivatives 3a, 3h and 9-deoxy-arctigenin phenethyl ether derivatives 6a, 6c, 6d activate AMPK more potently than arctigenin. Moreover, the 2-(3,4-dimethoxyphenyl)ethyl ether moiety of 6c has been demonstrated as a potential functional group to improve the effect of AMPK phosphorylation. The structural optimization of arctigenin leads to the identification of 6c as a promising lead compound that exhibits excellent activity in AMPK activation. PMID:23673223

  7. The AMPK activator R419 improves exercise capacity and skeletal muscle insulin sensitivity in obese mice

    Marcinko, Katarina; Bujak, Adam L.; Lally, James S.V.; Ford, Rebecca J.; Wong, Tammy H.; Smith, Brennan K.; Kemp, Bruce E.; Jenkins, Yonchu; Li, Wei; Kinsella, Todd M.; Hitoshi, Yasumichi; Steinberg, Gregory R.

    2015-01-01

    Objective Skeletal muscle AMP-activated protein kinase (AMPK) is important for regulating glucose homeostasis, mitochondrial content and exercise capacity. R419 is a mitochondrial complex-I inhibitor that has recently been shown to acutely activate AMPK in myotubes. Our main objective was to examine whether R419 treatment improves insulin sensitivity and exercise capacity in obese insulin resistant mice and whether skeletal muscle AMPK was important for mediating potential effects. Methods Glucose homeostasis, insulin sensitivity, exercise capacity, and electron transport chain content/activity were examined in wildtype (WT) and AMPK β1β2 muscle-specific null (AMPK-MKO) mice fed a high-fat diet (HFD) with or without R419 supplementation. Results There was no change in weight gain, adiposity, glucose tolerance or insulin sensitivity between HFD-fed WT and AMPK-MKO mice. In both HFD-fed WT and AMPK-MKO mice, R419 enhanced insulin tolerance, insulin-stimulated glucose disposal, skeletal muscle 2-deoxyglucose uptake, Akt phosphorylation and glucose transporter 4 (GLUT4) content independently of alterations in body mass. In WT, but not AMPK-MKO mice, R419 improved treadmill running capacity. Treatment with R419 increased muscle electron transport chain content and activity in WT mice; effects which were blunted in AMPK-MKO mice. Conclusions Treatment of obese mice with R419 improved skeletal muscle insulin sensitivity through a mechanism that is independent of skeletal muscle AMPK. R419 also increases exercise capacity and improves mitochondrial function in obese WT mice; effects that are diminished in the absence of skeletal muscle AMPK. These findings suggest that R419 may be a promising therapy for improving whole-body glucose homeostasis and exercise capacity. PMID:26413470

  8. Modulation of de novo purine biosynthesis leads to activation of AMPK and results in improved glucose handling and insulin sensitivity

    Sadasivan, Satish Kumar; Vasamsetti, Balamuralikrishna; Singh, Jaideep; Siddaraju, Nethra; Khan, Khaiser Mehdi; Oommen, Anup Mammen; Jagannath, Madanalli R; Rao, Raghavendra Pralhada

    2014-01-01

    Background AMP activated protein kinase (AMPK) regulates key metabolic reactions and plays a major role in glucose homeostasis. Activating the AMPK is considered as one of the potential therapeutic strategies in treating type-2 diabetes. However, targeting AMPK by small molecule mediated approach can be challenging owing to diverse isoforms of the enzyme and their varied combination in different tissues. In the current study we employ a novel strategy of achieving AMPK activation through incr...

  9. Activation of AMPK alpha and gamma-isoform complexes in the intact ischemic rat heart

    AMP-activated protein kinase (AMPK) plays a key role in modulating cellular metabolic processes. AMPK, a serine-threonine kinase, is a heterotrimeric complex of catalytic alpha-subunits and regulatory beta- and gamma-subunits with multiple isoforms. Mutations in the cardiac gamma(2)-isoform have bee...

  10. A Critical SUMO1 Modification of LKB1 Regulates AMPK Activity during Energy Stress

    Ritho, Joan

    2015-07-23

    SUMOylation has been implicated in cellular stress adaptation, but its role in regulating liver kinase B1 (LKB1), a major upstream kinase of the energy sensor AMP-activated protein kinase (AMPK), is unknown. Here, we show that energy stress triggers an increase in SUMO1 modification of LKB1, despite a global reduction in both SUMO1 and SUMO2/3 conjugates. During metabolic stress, SUMO1 modification of LKB1 lysine 178 is essential in promoting its interaction with AMPK via a SUMO-interacting motif (SIM) essential for AMPK activation. The LKB1 K178R SUMO mutant had defective AMPK signaling and mitochondrial function, inducing death in energy-deprived cells. These results provide additional insight into how LKB1-AMPK signaling is regulated during energy stress, and they highlight the critical role of SUMOylation in maintaining the cell’s energy equilibrium.

  11. Combined pharmacological activation of AMPK and PPAR δ potentiates the effects of exercise in trained mice

    Manio, Mark Christian C.; Inoue, Kazuo; Fujitani, Mina; Matsumura, Shigenobu; Fushiki, Tohru

    2016-01-01

    Abstract The combined activation of the cellular energy sensor AMP‐activated protein kinase (AMPK) and the nuclear transcription factor peroxisome proliferator‐activated receptor delta (PPAR δ) has been demonstrated to improve endurance and muscle function by mimicking the effects of exercise training. However, their combined pharmacological activation with exercise training has not been explored. Balb/c mice were trained on a treadmill and administered both the AMPK activator AICAR and the P...

  12. Role of adenosine 5'-monophosphate-activated protein kinase in interleukin-6 release from isolated mouse skeletal muscle

    Glund, Stephan; Treebak, Jonas Thue; Long, Yun Chau;

    2009-01-01

    IL-6 is released from skeletal muscle during exercise and has consequently been implicated to mediate beneficial effects on whole-body metabolism. Using 5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICAR), a pharmacological activator of 5'-AMP-activated protein kinase (AMPK), we tested...... the hypothesis that AMPK modulates IL-6 release from isolated muscle. Skeletal muscle from AMPKalpha2 kinase-dead transgenic, AMPKalpha1 knockout (KO) and AMPKgamma3 KO mice and respective wild-type littermates was incubated in vitro, in the absence or presence of 2 mmol/liter AICAR. Skeletal muscle...... from wild-type mice was also incubated with the AMPK activator A-769662. Incubation of mouse glycolytic extensor digitorum longus and oxidative soleus muscle for 2 h was associated with profound IL-6 mRNA production and protein release, which was suppressed by AICAR (P < 0.001). Basal IL-6 release from...

  13. Blockade of MerTK Activation by AMPK Inhibits RPE Cell Phagocytosis.

    Qin, Suofu

    2016-01-01

    Timely removal of shed photoreceptor outer segments by retinal pigment epithelial cells (RPE) plays a key role in biological renewal of these highly peroxidizable structures and in maintenance of retina health. How environmental stress cause RPE cell dysfunction is undefined however. AMP-activated protein kinase (AMPK), a heterotrimer of a catalytic α subunit and regulatory β and γ subunits, maintains energy homeostasis by limiting energy utilization and/or promoting energy production when energy supply is compromised. Intriguingly, AMPK has been shown to be important in functions of RPE cells. In this mini-review, the role and mechanisms of AMPK in controlling RPE cell phagocytosis are discussed. PMID:26427488

  14. Crosstalk between AMPK activation and angiotensin II-induced hypertrophy in cardiomyocytes: the role of mitochondria

    Hernández, Jessica Soto; Barreto-Torres, Giselle; Kuznetsov, Andrey V.; Khuchua, Zaza; Javadov, Sabzali

    2014-01-01

    AMP-kinase (AMPK) activation reduces cardiac hypertrophy, although underlying molecular mechanisms remain unclear. In this study, we elucidated the anti-hypertrophic action of metformin, specifically, the role of the AMPK/eNOS/p53 pathway. H9c2 rat cardiomyocytes were treated with angiotensin II (AngII) for 24 hrs in the presence or absence of metformin (AMPK agonist), losartan [AngII type 1 receptor (AT1R) blocker], Nω-nitro-L-arginine methyl ester (L-NAME, pan-NOS inhibitor), splitomicin (S...

  15. Adenosine Monophosphate-Activated Protein Kinase (AMPK) as a Diverse Therapeutic Target: A Computational Perspective.

    Ramesh, M; Vepuri, Suresh B; Oosthuizen, Frasia; Soliman, Mahmoud E

    2016-02-01

    Adenosine monophosphate-activated protein kinase (AMPK) is viewed as a privileged therapeutic target for several diseases such as cancer, diabetes, inflammation, obesity, etc. In addition, AMPK has entered the limelight of current drug discovery with its evolution as a key metabolic regulator. AMPK also plays a key role in the maintenance of cellular energy homeostasis. Structurally, AMPK is a heterotrimeric protein, which consists of three protein subunits (α, β, and γ). The crystal structure of AMPK was solved, and several computational studies including homology modeling, molecular docking, molecular dynamics, and QSAR have been reported in order to explore the structure and function of this diverse therapeutic target. In this review, we present a comprehensive up-to-date overview on the computational and molecular modeling approaches that have been carried out on AMPK in order to understand its structure, function, dynamics, and its drug binding landscape. Information provided in this review would be of great interest to a wide pool of researchers involved in the design of new molecules against various diseases where AMPK plays a predominant role. Graphical Abstract ᅟ. PMID:26541160

  16. Fenofibrate activates AMPK and increases eNOS phosphorylation in HUVEC

    Fenofibrate improves endothelial function by lipid-lowering and anti-inflammatory effects. Additionally, fenofibrate has been demonstrated to upregulate endothelial nitric oxide synthase (eNOS). AMP-activated protein kinase (AMPK) has been reported to phosphorylate eNOS at Ser-1177 and stimulate vascular endothelium-derived nitric oxide (NO) production. We report here that fenofibrate activates AMPK and increases eNOS phosphorylation and NO production in human umbilical vein endothelial cells (HUVEC). Incubation of HUVEC with fenofibrate increased the phosphorylation of AMPK and acetyl-CoA carboxylase. Fenofibrate simultaneously increased eNOS phosphorylation and NO production. Inhibitors of protein kinase A and phosphatidylinositol 3-kinase failed to suppress the fenofibrate-induced eNOS phosphorylation. Neither bezafibrate nor WY-14643 activated AMPK in HUVEC. Furthermore, fenofibrate activated AMPK without requiring any transcriptional activities. These results indicate that fenofibrate stimulates eNOS phosphorylation and NO production through AMPK activation, which is suggested to be a novel characteristic of this agonist and unrelated to its effects on peroxisome proliferator-activated receptor α

  17. AMPK activation regulates apoptosis, adipogenesis, and lipolysis by eIF2α in adipocytes

    AMP-activated protein kinase (AMPK) is a metabolic master switch regulating glucose and lipid metabolism. Recently, AMPK has been implicated in the control of adipose tissue content. Yet, the nature of this action is controversial. We examined the effect on F442a adipocytes of the AMPK activator-AICAR. Activation of AMPK induced dose-dependent apoptotic cell death, inhibition of lipolysis, and downregulatation key adipogenic genes, such as peroxisome proliferator-activated receptor (PPARγ) and CCAAT/enhancer-binding protein alpha (C/EBPα). We have identified the α-subunit of the eukaryotic initiation factor-2 (eIF2α) as a target gene which is phosphorylated following AICAR treatment. Such phosphorylation is one of the best-characterized mechanisms for downregulating protein synthesis. 2-Aminopurine (2-AP), an inhibitor of eIF2α kinases, could overcome the apoptotic effect of AICAR, abolishing the reduction of PPARγ and C/EBPα and the lipolytic properties of AMPK. Thus, AMPK may diminish adiposity via reduction of fat cell number through eIF2α-dependent translation shutdown

  18. Use of metformin alone is not associated with survival outcomes of colorectal cancer cell but AMPK activator AICAR sensitizes anticancer effect of 5-fluorouracil through AMPK activation.

    Xinbing Sui

    Full Text Available Colorectal cancer (CRC is still the third most common cancer and the second most common causes of cancer-related death around the world. Metformin, a biguanide, which is widely used for treating diabetes mellitus, has recently been shown to have a suppressive effect on CRC risk and mortality, but not all laboratory studies suggest that metformin has antineoplastic activity. Here, we investigated the effect of metformin and AMPK activator AICAR on CRC cells proliferation. As a result, metformin did not inhibit cell proliferation or induce apoptosis for CRC cell lines in vitro and in vivo. Different from metformin, AICAR emerged antitumor activity and sensitized anticancer effect of 5-FU on CRC cells in vitro and in vivo. In further analysis, we show that AMPK activation may be a key molecular mechanism for the additive effect of AICAR. Taken together, our results suggest that metformin has not antineoplastic activity for CRC cells as a single agent but AMPK activator AICAR can induce apoptosis and enhance the cytotoxic effect of 5-FU through AMPK activation.

  19. AMP-activated protein kinase induces actin cytoskeleton reorganization in epithelial cells

    Miranda, Lisa; Carpentier, Sarah; Platek, Anna; Hussain, Nusrat; Gueuning, Marie-Agnes; Vertommen, Didier; Ozkan, Yurda; Sid, Brice; Hue, Louis; Courtoy, Pierre J.; Rider, Mark H. [de Duve Institute, Universite catholique de Louvain, Avenue Hippocrate, B-1200 Brussels (Belgium); Horman, Sandrine, E-mail: sandrine.horman@uclouvain.be [Institute of Experimental and Clinical Research - Pole of Cardiovascular Research, Universite catholique de Louvain, Avenue Hippocrate, B-1200 Brussels (Belgium)

    2010-06-04

    AMP-activated protein kinase (AMPK), a known regulator of cellular and systemic energy balance, is now recognized to control cell division, cell polarity and cell migration, all of which depend on the actin cytoskeleton. Here we report the effects of A769662, a pharmacological activator of AMPK, on cytoskeletal organization and signalling in epithelial Madin-Darby canine kidney (MDCK) cells. We show that AMPK activation induced shortening or radiation of stress fibers, uncoupling from paxillin and predominance of cortical F-actin. In parallel, Rho-kinase downstream targets, namely myosin regulatory light chain and cofilin, were phosphorylated. These effects resembled the morphological changes in MDCK cells exposed to hyperosmotic shock, which led to Ca{sup 2+}-dependent AMPK activation via calmodulin-dependent protein kinase kinase-{beta}(CaMKK{beta}), a known upstream kinase of AMPK. Indeed, hypertonicity-induced AMPK activation was markedly reduced by the STO-609 CaMKK{beta} inhibitor, as was the increase in MLC and cofilin phosphorylation. We suggest that AMPK links osmotic stress to the reorganization of the actin cytoskeleton.

  20. Atrial natriuretic peptide regulates lipid mobilization and oxygen consumption in human adipocytes by activating AMPK

    Highlights: → Treatment of differentiated human adipocytes with atrial natriuretic peptide (ANP) increased lipolysis and oxygen consumption by activating AMP-activated protein kinase (AMPK). → ANP stimulated lipid mobilization by selective activation of the alpha2 subunit of AMPK and increased energy utilization through activation of both the alpha1 and alpha2 subunits of AMPK. → ANP enhanced adipocyte mitochondrial oxidative capacity as evidenced by induction of oxidative mitochondrial genes and increase in oxygen consumption. → Exposure of human adipocytes to fatty acids and (TNFα) induced insulin resistance and decreased expression of mitochondrial genes which was restored to normal by ANP. -- Abstract: Atrial natriuretic peptide (ANP) has been shown to regulate lipid and carbohydrate metabolism providing a possible link between cardiovascular function and metabolism by mediating the switch from carbohydrate to lipid mobilization and oxidation. ANP exerts a potent lipolytic effect via cGMP-dependent protein kinase (cGK)-I mediated-stimulation of AMP-activated protein kinase (AMPK). Activation of the ANP/cGK signaling cascade also promotes muscle mitochondrial biogenesis and fat oxidation. Here we demonstrate that ANP regulates lipid metabolism and oxygen utilization in differentiated human adipocytes by activating the alpha2 subunit of AMPK. ANP treatment increased lipolysis by seven fold and oxygen consumption by two fold, both of which were attenuated by inhibition of AMPK activity. ANP-induced lipolysis was shown to be mediated by the alpha2 subunit of AMPK as introduction of dominant-negative alpha2 subunit of AMPK attenuated ANP effects on lipolysis. ANP-induced activation of AMPK enhanced mitochondrial oxidative capacity as evidenced by a two fold increase in oxygen consumption and induction of mitochondrial genes, including carnitine palmitoyltransferase 1A (CPT1a) by 1.4-fold, cytochrome C (CytC) by 1.3-fold, and peroxisome proliferator-activated

  1. Atrial natriuretic peptide regulates lipid mobilization and oxygen consumption in human adipocytes by activating AMPK

    Souza, Sandra C. [Translational Sciences - Translational Medicine, Novartis Institutes for Biomedical Research, Inc., 220 Massachusetts Avenue, Cambridge, MA 02139 (United States); Chau, Mary D.L.; Yang, Qing [Cardiovascular and Metabolism Disease Area, Novartis Institutes for Biomedical Research, Inc., 100 Technology Square, Cambridge, MA 02139 (United States); Gauthier, Marie-Soleil [Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA 02140 (United States); Clairmont, Kevin B.; Wu, Zhidan; Gromada, Jesper [Cardiovascular and Metabolism Disease Area, Novartis Institutes for Biomedical Research, Inc., 100 Technology Square, Cambridge, MA 02139 (United States); Dole, William P., E-mail: bill.dole@novartis.com [Translational Sciences - Translational Medicine, Novartis Institutes for Biomedical Research, Inc., 220 Massachusetts Avenue, Cambridge, MA 02139 (United States)

    2011-07-08

    Highlights: {yields} Treatment of differentiated human adipocytes with atrial natriuretic peptide (ANP) increased lipolysis and oxygen consumption by activating AMP-activated protein kinase (AMPK). {yields} ANP stimulated lipid mobilization by selective activation of the alpha2 subunit of AMPK and increased energy utilization through activation of both the alpha1 and alpha2 subunits of AMPK. {yields} ANP enhanced adipocyte mitochondrial oxidative capacity as evidenced by induction of oxidative mitochondrial genes and increase in oxygen consumption. {yields} Exposure of human adipocytes to fatty acids and (TNF{alpha}) induced insulin resistance and decreased expression of mitochondrial genes which was restored to normal by ANP. -- Abstract: Atrial natriuretic peptide (ANP) has been shown to regulate lipid and carbohydrate metabolism providing a possible link between cardiovascular function and metabolism by mediating the switch from carbohydrate to lipid mobilization and oxidation. ANP exerts a potent lipolytic effect via cGMP-dependent protein kinase (cGK)-I mediated-stimulation of AMP-activated protein kinase (AMPK). Activation of the ANP/cGK signaling cascade also promotes muscle mitochondrial biogenesis and fat oxidation. Here we demonstrate that ANP regulates lipid metabolism and oxygen utilization in differentiated human adipocytes by activating the alpha2 subunit of AMPK. ANP treatment increased lipolysis by seven fold and oxygen consumption by two fold, both of which were attenuated by inhibition of AMPK activity. ANP-induced lipolysis was shown to be mediated by the alpha2 subunit of AMPK as introduction of dominant-negative alpha2 subunit of AMPK attenuated ANP effects on lipolysis. ANP-induced activation of AMPK enhanced mitochondrial oxidative capacity as evidenced by a two fold increase in oxygen consumption and induction of mitochondrial genes, including carnitine palmitoyltransferase 1A (CPT1a) by 1.4-fold, cytochrome C (CytC) by 1.3-fold, and

  2. Activation of AMPK inhibits cervical cancer cell growth through AKT/FOXO3a/FOXM1 signaling cascade

    Although advanced-stage cervical cancer can benefit from current treatments, approximately 30% patients may fail after definitive treatment eventually. Therefore, exploring alternative molecular therapeutic approaches is imperatively needed for this disease. We have recently shown that activation of AMP-activated protein kinase (AMPK), a metabolic sensor, hampers cervical cancer cell growth through blocking the Wnt/β-catenin signaling activity. Here, we report that activated AMPK (p-AMPK) also inhibits cervical cancer cell growth by counteracting FOXM1 function. Effect of the activation of AMPK on FOXM1 expression was examined by hypoxia and glucose deprivation, as well as pharmacological AMPK activators such as A23187, AICAR and metformin. RT Q-PCR and Western blot analysis were employed to investigate the activities of AMPK, FOXM1 and AKT/FOXO3a signaling. Consistent with our previous findings, the activation of AMPK by either AMPK activators such as AICAR, A23187, metformin, glucose deprivation or hypoxia significantly inhibited the cervical cancer cell growth. Importantly, we found that activated AMPK activity was concomitantly associated with the reduction of both the mRNA and protein levels of FOXM1. Mechanistically, we showed that activated AMPK was able to reduce AKT mediated phosphorylation of p-FOXO3a (Ser253). Interestingly, activated AMPK could not cause any significant changes in FOXM1 in cervical cancer cells in which endogenous FOXO3a levels were knocked down using siRNAs, suggesting that FOXO3a is involved in the suppression of FOXM1. Taken together, our results suggest the activated AMPK impedes cervical cancer cell growth through reducing the expression of FOXM1

  3. AMPK activation protects cells from oxidative stress-induced senescence via autophagic flux restoration and intracellular NAD(+) elevation.

    Han, Xiaojuan; Tai, Haoran; Wang, Xiaobo; Wang, Zhe; Zhou, Jiao; Wei, Xiawei; Ding, Yi; Gong, Hui; Mo, Chunfen; Zhang, Jie; Qin, Jianqiong; Ma, Yuanji; Huang, Ning; Xiang, Rong; Xiao, Hengyi

    2016-06-01

    AMPK activation is beneficial for cellular homeostasis and senescence prevention. However, the molecular events involved in AMPK activation are not well defined. In this study, we addressed the mechanism underlying the protective effect of AMPK on oxidative stress-induced senescence. The results showed that AMPK was inactivated in senescent cells. However, pharmacological activation of AMPK by metformin and berberine significantly prevented the development of senescence and, accordingly, inhibition of AMPK by Compound C was accelerated. Importantly, AMPK activation prevented hydrogen peroxide-induced impairment of the autophagic flux in senescent cells, evidenced by the decreased p62 degradation, GFP-RFP-LC3 cancellation, and activity of lysosomal hydrolases. We also found that AMPK activation restored the NAD(+) levels in the senescent cells via a mechanism involving mostly the salvage pathway for NAD(+) synthesis. In addition, the mechanistic relationship of autophagic flux and NAD(+) synthesis and the involvement of mTOR and Sirt1 activities were assessed. In summary, our results suggest that AMPK prevents oxidative stress-induced senescence by improving autophagic flux and NAD(+) homeostasis. This study provides a new insight for exploring the mechanisms of aging, autophagy and NAD(+) homeostasis, and it is also valuable in the development of innovative strategies to combat aging. PMID:26890602

  4. Co-activation of AMPK and mTORC1 Induces Cytotoxicity in Acute Myeloid Leukemia

    Pierre Sujobert

    2015-06-01

    Full Text Available AMPK is a master regulator of cellular metabolism that exerts either oncogenic or tumor suppressor activity depending on context. Here, we report that the specific AMPK agonist GSK621 selectively kills acute myeloid leukemia (AML cells but spares normal hematopoietic progenitors. This differential sensitivity results from a unique synthetic lethal interaction involving concurrent activation of AMPK and mTORC1. Strikingly, the lethality of GSK621 in primary AML cells and AML cell lines is abrogated by chemical or genetic ablation of mTORC1 signaling. The same synthetic lethality between AMPK and mTORC1 activation is established in CD34-positive hematopoietic progenitors by constitutive activation of AKT or enhanced in AML cells by deletion of TSC2. Finally, cytotoxicity in AML cells from GSK621 involves the eIF2α/ATF4 signaling pathway that specifically results from mTORC1 activation. AMPK activation may represent a therapeutic opportunity in mTORC1-overactivated cancers.

  5. Co-activation of AMPK and mTORC1 Induces Cytotoxicity in Acute Myeloid Leukemia.

    Sujobert, Pierre; Poulain, Laury; Paubelle, Etienne; Zylbersztejn, Florence; Grenier, Adrien; Lambert, Mireille; Townsend, Elizabeth C; Brusq, Jean-Marie; Nicodeme, Edwige; Decrooqc, Justine; Nepstad, Ina; Green, Alexa S; Mondesir, Johanna; Hospital, Marie-Anne; Jacque, Nathalie; Christodoulou, Alexandra; Desouza, Tiffany A; Hermine, Olivier; Foretz, Marc; Viollet, Benoit; Lacombe, Catherine; Mayeux, Patrick; Weinstock, David M; Moura, Ivan C; Bouscary, Didier; Tamburini, Jerome

    2015-06-01

    AMPK is a master regulator of cellular metabolism that exerts either oncogenic or tumor suppressor activity depending on context. Here, we report that the specific AMPK agonist GSK621 selectively kills acute myeloid leukemia (AML) cells but spares normal hematopoietic progenitors. This differential sensitivity results from a unique synthetic lethal interaction involving concurrent activation of AMPK and mTORC1. Strikingly, the lethality of GSK621 in primary AML cells and AML cell lines is abrogated by chemical or genetic ablation of mTORC1 signaling. The same synthetic lethality between AMPK and mTORC1 activation is established in CD34-positive hematopoietic progenitors by constitutive activation of AKT or enhanced in AML cells by deletion of TSC2. Finally, cytotoxicity in AML cells from GSK621 involves the eIF2α/ATF4 signaling pathway that specifically results from mTORC1 activation. AMPK activation may represent a therapeutic opportunity in mTORC1-overactivated cancers. PMID:26004183

  6. Sex-specific regulation of AMP-activated protein kinase (AMPK) in the Pacific oyster Crassostrea gigas.

    Guévélou, Eric; Huvet, Arnaud; Galindo-Sánchez, Clara E; Milan, Massimo; Quillien, Virgile; Daniel, Jean-Yves; Quéré, Claudie; Boudry, Pierre; Corporeau, Charlotte

    2013-10-01

    The hermaphrodite Pacific oyster Crassostrea gigas displays a high energy allocation to reproduction. We studied the expression of AMP-activated protein kinase (AMPK) during gametogenesis in the gonad and characterized the mRNA sequences of the AMPK subunits: the AMPK alpha mRNA sequence was previously characterized; we identified AMPK beta, AMPK gamma, and mRNAs of putative AMPK-related targets following bioinformatics mining on existing genomic resources. We analyzed the mRNA expression of the AMPK alpha, beta, and gamma subunits in the gonads of male and female oysters through a reproductive cycle, and we quantified the mRNA expression of genes belonging to fatty acid and glucose metabolism. AMPK alpha mRNA levels were more abundant in males at the first stage of gametogenesis, when mitotic activity and the differentiation of germinal cells occur, and were always more abundant in males than in females. Some targets of fatty acid and glucose metabolism appeared to be correlated with the expression of AMPK subunits at the mRNA level. We then analyzed the sex-specific AMPK activity by measuring the phosphorylation of the catalytic AMPK alpha protein and its expression at the protein level. Both the amount of AMPK alpha protein and threonine 172 phosphorylation appeared to be almost totally inhibited in mature female gonads at stage 3, at the time when accumulation of reserves in oocytes was promoted, while it remained at a high level in mature spermatozoa. Its activation might play a sex-dependent role in the management of energy during gametogenesis in oyster. PMID:23926284

  7. Increased skeletal muscle glucose uptake by rosemary extract through AMPK activation.

    Naimi, Madina; Tsakiridis, Theodoros; Stamatatos, Theocharis C; Alexandropoulos, Dimitris I; Tsiani, Evangelia

    2015-04-01

    Stimulation of the energy sensor AMP-activated kinase (AMPK) has been viewed as a targeted approach to increase glucose uptake by skeletal muscle and control blood glucose homeostasis. Rosemary extract (RE) has been reported to activate AMPK in hepatocytes and reduce blood glucose levels in vivo but its effects on skeletal muscle are not known. In the present study, we examined the effects of RE and the mechanism of regulation of glucose uptake in muscle cells. RE stimulated glucose uptake in L6 myotubes in a dose- and time-dependent manner. Maximum stimulation was seen with 5 μg/mL of RE for 4 h (184% ± 5.07% of control, p < 0.001), a response comparable to maximum insulin (207% ± 5.26%, p < 0.001) and metformin (216% ± 8.77%, p < 0.001) stimulation. RE did not affect insulin receptor substrate 1 and Akt phosphorylation but significantly increased AMPK and acetyl-CoA carboxylase phosphorylation. Furthermore, the RE-stimulated glucose uptake was significantly reduced by the AMPK inhibitor compound C, but remained unchanged by the PI3K inhibitor, wortmannin. RE did not affect GLUT4 or GLUT1 glucose transporter translocation in contrast with a significant translocation of both transporters seen with insulin or metformin treatment. Our study is the first to show a direct effect of RE on muscle cell glucose uptake by a mechanism that involves AMPK activation. PMID:25794239

  8. 5'-Monophosphate-activated protein kinase (AMPK) improves autophagic activity in diabetes and diabetic complications

    Fan Yao; Ming Zhang; Li Chen

    2015-01-01

    Diabetes mellitus (DM), an endocrine disorder, will be one of the leading causes of death world-wide in about two decades. Cellular injuries and disorders of energy metabolism are two key factors in the pathogenesis of diabetes, which also become the important causes for the process of diabetic complications. AMPK is a key enzyme in maintaining metabolic homeostasis and has been implicated in the activation of autophagy in distinct tissues. An increasing number of researchers have confirmed t...

  9. Interleukin-18 activates skeletal muscle AMPK and reduces weight gain and insulin resistance in mice

    Madsen, Birgitte Lindegaard; Matthews, Vance B; Brandt, Claus;

    2013-01-01

    receptor (IL-18R(-/-)), fed a standard chow or high fat diet (HFD). We next performed gain of function experiments in skeletal muscle, in vitro, ex vivo and in vivo. We show that IL-18 is implicated in metabolic homeostasis, inflammation and insulin resistance via mechanisms involving the activation of......-18 into skeletal muscle activated AMPK and concomitantly inhibited high fat diet-induced weight gain. In summary IL-18 enhances AMPK signaling and lipid oxidation in skeletal muscle implicating IL-18 in metabolic homeostasis....

  10. Higher skeletal muscle alpha2AMPK activation and lower energy charge and fat oxidation in men than in women during submaximal exercise

    Roepstorff, Carsten; Thiele, Maja; Hillig, Thore;

    2006-01-01

    5'AMP-activated protein kinase (AMPK) is an energy sensor activated by perturbed cellular energy status such as during muscle contraction. Activated AMPK is thought to regulate several key metabolic pathways. We used sex comparison to investigate whether AMPK signalling in skeletal muscle regulat...

  11. Mitochondria related peptide MOTS-c suppresses ovariectomy-induced bone loss via AMPK activation.

    Ming, Wei; Lu, Gan; Xin, Sha; Huanyu, Lu; Yinghao, Jiang; Xiaoying, Lei; Chengming, Xu; Banjun, Ruan; Li, Wang; Zifan, Lu

    2016-08-01

    Therapeutic targeting bone loss has been the focus of the study in osteoporosis. The present study is intended to evaluate whether MOTS-c, a novel mitochondria related 16 aa peptide, can protect mice from ovariectomy-induced osteoporosis. After ovary removal, the mice were injected with MOTS-c at a dose of 5 mg/kg once a day for 12 weeks. Our results showed that MOTS-c treatment significantly alleviated bone loss, as determined by micro-CT examination. Mechanistically, we found that the receptor activator of nuclear factor-κB ligand (RANKL) induced osteoclast differentiation was remarkably inhibited by MOTS-c. Moreover, MOTS-c increased phosphorylated AMPK levels, and compound C, an AMPK inhibitor, could partially abrogate the effects of the MOTS-c on osteoclastogenesis. Thus, our findings provide evidence that MOTS-c may exert as an inhibitor of osteoporosis via AMPK dependent inhibition of osteoclastogenesis. PMID:27237975

  12. N-Hydroxycinnamide Derivatives of Osthole Ameliorate Hyperglycemia through Activation of AMPK and p38 MAPK

    Wei-Hwa Lee

    2015-03-01

    Full Text Available Our previous studies found that osthole markedly reduced blood glucose levels in both db/db and ob/ob mice. To improve the antidiabetic activity of osthole, a series of N-hydroxycinnamide derivatives of osthole were synthesized, and their hypoglycemia activities were examined in vitro and in vivo. Both N-hydroxycinnamide derivatives of osthole, OHC-4p and OHC-2m, had the greatest potential for activating AMPK and increasing glucose uptake by L6 skeletal muscle cells. In addition, OHC-4p and OHC-2m time- and dose-dependently increased phosphorylation levels of AMPK and p38 MAPK. The AMPK inhibitor, compound C, and the p38 MAPK inhibitor, SB203580, significantly reversed activation of AMPK and p38 MAPK, respectively, in OHC-4p- and OHC-2m-treated cells. Compound C and SB203580 also inhibited glucose uptake induced by OHC-4p and OHC-2m. Next, we found that OHC-4p and OHC-2m significantly increased glucose transporter 4 (GLUT4 translocation to plasma membranes and counteracted hyperglycemia in mice with streptozotocin-induced diabetes. These results suggest that activation of AMPK and p38 MAPK by OHC-4p and OHC-2m is associated with increased glucose uptake and GLUT4 translocation and subsequently led to amelioration of hyperglycemia. Therefore, OHC-4p and OHC-2m might have potential as antidiabetic agents for treating type 2 diabetes. Our previous studies found that osthole markedly reduced blood glucose levels in both db/db and ob/ob mice. To improve the antidiabetic activity of osthole, a series of N-hydroxycinnamide derivatives of osthole were synthesized, and their hypoglycemia activities were examined in vitro and in vivo. Both N-hydroxycinnamide derivatives of osthole, OHC-4p and OHC-2m, had the greatest potential for activating AMPK and increasing glucose uptake by L6 skeletal muscle cells. In addition, OHC-4p and OHC-2m time- and dose-dependently increased phosphorylation levels of AMPK and p38 MAPK. The AMPK inhibitor, compound C, and the

  13. N-hydroxycinnamide derivatives of osthole ameliorate hyperglycemia through activation of AMPK and p38 MAPK.

    Lee, Wei-Hwa; Wu, Hsueh-Hsia; Huang, Wei-Jan; Li, Yi-Ning; Lin, Ren-Jye; Lin, Shyr-Yi; Liang, Yu-Chih

    2015-01-01

    Our previous studies found that osthole markedly reduced blood glucose levels in both db/db and ob/ob mice. To improve the antidiabetic activity of osthole, a series of N-hydroxycinnamide derivatives of osthole were synthesized, and their hypoglycemia activities were examined in vitro and in vivo. Both N-hydroxycinnamide derivatives of osthole, OHC-4p and OHC-2m, had the greatest potential for activating AMPK and increasing glucose uptake by L6 skeletal muscle cells. In addition, OHC-4p and OHC-2m time- and dose-dependently increased phosphorylation levels of AMPK and p38 MAPK. The AMPK inhibitor, compound C, and the p38 MAPK inhibitor, SB203580, significantly reversed activation of AMPK and p38 MAPK, respectively, in OHC-4p- and OHC-2m-treated cells. Compound C and SB203580 also inhibited glucose uptake induced by OHC-4p and OHC-2m. Next, we found that OHC-4p and OHC-2m significantly increased glucose transporter 4 (GLUT4) translocation to plasma membranes and counteracted hyperglycemia in mice with streptozotocin-induced diabetes. These results suggest that activation of AMPK and p38 MAPK by OHC-4p and OHC-2m is associated with increased glucose uptake and GLUT4 translocation and subsequently led to amelioration of hyperglycemia. Therefore, OHC-4p and OHC-2m might have potential as antidiabetic agents for treating type 2 diabetes. Our previous studies found that osthole markedly reduced blood glucose levels in both db/db and ob/ob mice. To improve the antidiabetic activity of osthole, a series of N-hydroxycinnamide derivatives of osthole were synthesized, and their hypoglycemia activities were examined in vitro and in vivo. Both N-hydroxycinnamide derivatives of osthole, OHC-4p and OHC-2m, had the greatest potential for activating AMPK and increasing glucose uptake by L6 skeletal muscle cells. In addition, OHC-4p and OHC-2m time- and dose-dependently increased phosphorylation levels of AMPK and p38 MAPK. The AMPK inhibitor, compound C, and the p38 MAPK inhibitor

  14. A dual role for AMP-activated protein kinase (AMPK) during neonatal hypoxic-ischaemic brain injury in mice.

    Rousset, Catherine I; Leiper, Fiona C; Kichev, Anton; Gressens, Pierre; Carling, David; Hagberg, Henrik; Thornton, Claire

    2015-04-01

    Perinatal hypoxic-ischaemic encephalopathy (HIE) occurs in 1-2 in every 1000 term infants and the devastating consequences range from cerebral palsy, epilepsy and neurological deficit to death. Cellular damage post insult occurs after a delay and is mediated by a secondary neural energy failure. AMP-activated protein kinase (AMPK) is a sensor of cellular stress resulting from ATP depletion and/or calcium dysregulation, hallmarks of the neuronal cell death observed after HIE. AMPK activation has been implicated in the models of adult ischaemic injury but, as yet, there have been no studies defining its role in neonatal asphyxia. Here, we find that in an in vivo model of neonatal hypoxia-ischaemic and in oxygen/glucose deprivation in neurons, there is pathological activation of the calcium/calmodulin-dependent protein kinase kinase β (CaMKKβ)-AMPKα1 signalling pathway. Pharmacological inhibition of AMPK during the insult promotes neuronal survival but, conversely, inhibiting AMPK activity prior to the insult sensitizes neurons, exacerbating cell death. Our data have pathological relevance for neonatal HIE as prior sensitization such as exposure to bacterial infection (reported to reduce AMPK activity) produces a significant increase in injury. We show that in an in vivo model of neonatal hypoxia-ischaemic and in oxygen/glucose deprivation in neurons, there is a pathological activation of the CaMKKβ-AMPKα1 signalling pathway. Inhibiting AMPK during OGD promotes neuronal survival; conversely, inhibiting AMPK prior to OGD exacerbates cell death. Our data have clinical relevance as prior sensitization (e.g. exposure to bacterial infection reducing AMPK activity) increases injury. AMPK, AMP-activated protein kinase; HI, hypoxia-ischaemia; OGD, oxygen-glucose deprivation. PMID:25598140

  15. AMPK activators suppress cervical cancer cell growth through inhibition of DVL3 mediated Wnt/β-catenin signaling activity.

    H T Kwan

    Full Text Available Recent evidence has suggested that AMPK activators may be applied as therapeutic drugs in suppressing cancer cell growth. However, the molecular mechanism of their suppressive function in cancer cells is still unclear. Here we show that AMPK activators impair cervical cancer cell growth through the reduction of DVL3, a positive regulator in Wnt/β-catenin signaling and an oncogenic player in cervical cancer tumorigenesis. By western blot and immunohistochemical analyses, we demonstrated that DVL3 was frequently upregulated and significantly associated with elevated β-catenin (P = 0.009 and CyclinD1 (P = 0.009 expressions in cervical cancer. Enforced expression of DVL3 elevated β-catenin and augmented cervical cancer cell growth, verifying that DVL3-mediated Wnt/β-catenin activation is involved in cervical cancer oncogenesis. On the other aspect, we noted that the cervical cancer cell growth was remarkably suppressed by AMPK activators and such cell growth inhibition was in concomitant with the reduction of DVL3 protein level in dose- and time-dependent manners. Besides, impaired mTOR signaling activity also reduced DVL3 expression. In contrast, co-treatment with Compound C (AMPK inhibitor could significantly abrogate metformin induced DVL3 reduction. In addition, co-treatment with AM114 or MG132 (proteosomal inhibitors could partially restore DVL3 expression under the treatment of metformin. Further in vivo ubiquitination assay revealed that metformin could reduce DVL3 by ubiquitin/proteasomal degradation. To our knowledge, this is the first report showing the probable molecular mechanisms of that the AMPK activators suppress cervical cancer cell growth by impairing DVL3 protein synthesis via AMPK/mTOR signaling and/or partially promoting the proteasomal degradation of DVL3.

  16. Differential AMP-activated Protein Kinase (AMPK) Recognition Mechanism of Ca2+/Calmodulin-dependent Protein Kinase Kinase Isoforms.

    Fujiwara, Yuya; Kawaguchi, Yoshinori; Fujimoto, Tomohito; Kanayama, Naoki; Magari, Masaki; Tokumitsu, Hiroshi

    2016-06-24

    Ca(2+)/calmodulin-dependent protein kinase kinase β (CaMKKβ) is a known activating kinase for AMP-activated protein kinase (AMPK). In vitro, CaMKKβ phosphorylates Thr(172) in the AMPKα subunit more efficiently than CaMKKα, with a lower Km (∼2 μm) for AMPK, whereas the CaMKIα phosphorylation efficiencies by both CaMKKs are indistinguishable. Here we found that subdomain VIII of CaMKK is involved in the discrimination of AMPK as a native substrate by measuring the activities of various CaMKKα/CaMKKβ chimera mutants. Site-directed mutagenesis analysis revealed that Leu(358) in CaMKKβ/Ile(322) in CaMKKα confer, at least in part, a distinct recognition of AMPK but not of CaMKIα. PMID:27151216

  17. AMPK Activation by Metformin Suppresses Abnormal Extracellular Matrix Remodeling in Adipose Tissue and Ameliorates Insulin Resistance in Obesity.

    Luo, Ting; Nocon, Allison; Fry, Jessica; Sherban, Alex; Rui, Xianliang; Jiang, Bingbing; Xu, X Julia; Han, Jingyan; Yan, Yun; Yang, Qin; Li, Qifu; Zang, Mengwei

    2016-08-01

    Fibrosis is emerging as a hallmark of metabolically dysregulated white adipose tissue (WAT) in obesity. Although adipose tissue fibrosis impairs adipocyte plasticity, little is known about how aberrant extracellular matrix (ECM) remodeling of WAT is initiated during the development of obesity. Here we show that treatment with the antidiabetic drug metformin inhibits excessive ECM deposition in WAT of ob/ob mice and mice with diet-induced obesity, as evidenced by decreased collagen deposition surrounding adipocytes and expression of fibrotic genes including the collagen cross-linking regulator LOX Inhibition of interstitial fibrosis by metformin is likely attributable to the activation of AMPK and the suppression of transforming growth factor-β1 (TGF-β1)/Smad3 signaling, leading to enhanced systemic insulin sensitivity. The ability of metformin to repress TGF-β1-induced fibrogenesis is abolished by the dominant negative AMPK in primary cells from the stromal vascular fraction. TGF-β1-induced insulin resistance is suppressed by AMPK agonists and the constitutively active AMPK in 3T3L1 adipocytes. In omental fat depots of obese humans, interstitial fibrosis is also associated with AMPK inactivation, TGF-β1/Smad3 induction, aberrant ECM production, myofibroblast activation, and adipocyte apoptosis. Collectively, integrated AMPK activation and TGF-β1/Smad3 inhibition may provide a potential therapeutic approach to maintain ECM flexibility and combat chronically uncontrolled adipose tissue expansion in obesity. PMID:27207538

  18. A dual role for AMP‐activated protein kinase (AMPK) during neonatal hypoxic–ischaemic brain injury in mice

    Rousset, Catherine I.; Leiper, Fiona C.; Kichev, Anton; Gressens, Pierre; Carling, David; Hagberg, Henrik; Thornton, Claire

    2015-01-01

    Abstract Perinatal hypoxic–ischaemic encephalopathy (HIE) occurs in 1–2 in every 1000 term infants and the devastating consequences range from cerebral palsy, epilepsy and neurological deficit to death. Cellular damage post insult occurs after a delay and is mediated by a secondary neural energy failure. AMP‐activated protein kinase (AMPK) is a sensor of cellular stress resulting from ATP depletion and/or calcium dysregulation, hallmarks of the neuronal cell death observed after HIE. AMPK act...

  19. Polyphenol-Rich Propolis Extracts Strengthen Intestinal Barrier Function by Activating AMPK and ERK Signaling.

    Wang, Kai; Jin, Xiaolu; Chen, Yifan; Song, Zehe; Jiang, Xiasen; Hu, Fuliang; Conlon, Michael A; Topping, David L

    2016-01-01

    Propolis has abundant polyphenolic constituents and is used widely as a health/functional food. Here, we investigated the effects of polyphenol-rich propolis extracts (PPE) on intestinal barrier function in human intestinal epithelial Caco-2 cells, as well as in rats. In Caco-2 cells, PPE increased transepithelial electrical resistance and decreased lucifer yellow flux. PPE-treated cells showed increased expression of the tight junction (TJ) loci occludin and zona occludens (ZO)-1. Confocal microscopy showed organized expressions in proteins related to TJ assembly, i.e., occludin and ZO-1, in response to PPE. Furthermore, PPE led to the activation of AMPK, ERK1/2, p38, and Akt. Using selective inhibitors, we found that the positive effects of PPE on barrier function were abolished in cells in which AMPK and ERK1/2 signaling were inhibited. Moreover, rats fed a diet supplemented with PPE (0.3% in the diet) exhibited increased colonic epithelium ZO-1 expression. Overall, these data suggest that PPE strengthens intestinal barrier function by activating AMPK and ERK signaling and provide novel insights into the potential application of propolis for human gut health. PMID:27164138

  20. Polyphenol-Rich Propolis Extracts Strengthen Intestinal Barrier Function by Activating AMPK and ERK Signaling

    Kai Wang

    2016-05-01

    Full Text Available Propolis has abundant polyphenolic constituents and is used widely as a health/functional food. Here, we investigated the effects of polyphenol-rich propolis extracts (PPE on intestinal barrier function in human intestinal epithelial Caco-2 cells, as well as in rats. In Caco-2 cells, PPE increased transepithelial electrical resistance and decreased lucifer yellow flux. PPE-treated cells showed increased expression of the tight junction (TJ loci occludin and zona occludens (ZO-1. Confocal microscopy showed organized expressions in proteins related to TJ assembly, i.e., occludin and ZO-1, in response to PPE. Furthermore, PPE led to the activation of AMPK, ERK1/2, p38, and Akt. Using selective inhibitors, we found that the positive effects of PPE on barrier function were abolished in cells in which AMPK and ERK1/2 signaling were inhibited. Moreover, rats fed a diet supplemented with PPE (0.3% in the diet exhibited increased colonic epithelium ZO-1 expression. Overall, these data suggest that PPE strengthens intestinal barrier function by activating AMPK and ERK signaling and provide novel insights into the potential application of propolis for human gut health.

  1. Mangiferin decreases plasma free fatty acids through promoting its catabolism in liver by activation of AMPK.

    Yucun Niu

    Full Text Available Mangiferin has been shown to have the effect of improving dyslipidemia. Plasma free fatty acids (FFA are closely associated with blood lipid metabolism as well as many diseases including metabolic syndrome. This study is to investigate whether mangiferin has effects on FFA metabolism in hyperlipidemic rats. Wistar rats were fed a high-fat diet and administered mangiferin simultaneously for 6 weeks. Mangiferin (50, 100, 150 mg/kg BW decreased dose-dependently FFA and triglycerides (TG levels in plasma, and their accumulations in liver, but increased the β-hydroxybutyrate levels in both plasma and liver of hyperlipidemic rats. HepG2 cells were treated with oleic acid (OA, 0.2 mmol/L to simulate the condition of high level of plasma FFA in vitro, and were treated with different concentrations of mangiferin simultaneously for 24 h. We found that mangiferin significantly increased FFA uptake, significantly decreased intracellular FFA and TG accumulations in HepG2 cells. Mangiferin significantly increased AMP-activated protein kinase (AMPK phosphorylation and its downstream proteins involved in fatty acid translocase (CD36 and carnitine palmitoyltransferase 1 (CPT1, but significantly decreased acyl-CoA: diacylgycerol acyltransferase 2 (DGAT2 expression and acetyl-CoA carboxylase (ACC activity by increasing its phosphorylation level in both in vivo and in vitro studies. Furthermore, these effects were reversed by Compound C, an AMPK inhibitor in HepG2 cells. For upstream of AMPK, mangiferin increased AMP/ATP ratio, but had no effect on LKB1 phosphorylation. In conclusion, mangiferin decreased plasma FFA levels through promoting FFA uptake and oxidation, inhibiting FFA and TG accumulations by regulating the key enzymes expression in liver through AMPK pathway. Therefore, mangiferin is a possible beneficial natural compound for metabolic syndrome by improving FFA metabolism.

  2. FK866-induced NAMPT inhibition activates AMPK and downregulates mTOR signaling in hepatocarcinoma cells

    Schuster, Susanne, E-mail: Susanne.Schuster@medizin.uni-leipzig.de [Center for Pediatric Research Leipzig, University Hospital for Children and Adolescents, Faculty of Medicine, University of Leipzig, Liebigstr. 21, 04103 Leipzig (Germany); Penke, Melanie; Gorski, Theresa [Center for Pediatric Research Leipzig, University Hospital for Children and Adolescents, Faculty of Medicine, University of Leipzig, Liebigstr. 21, 04103 Leipzig (Germany); Gebhardt, Rolf [Institute of Biochemistry, Faculty of Medicine, University of Leipzig, Johannisallee 30, 04103 Leipzig (Germany); Weiss, Thomas S. [Children' s University Hospital, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg (Germany); Kiess, Wieland; Garten, Antje [Center for Pediatric Research Leipzig, University Hospital for Children and Adolescents, Faculty of Medicine, University of Leipzig, Liebigstr. 21, 04103 Leipzig (Germany)

    2015-03-06

    Background: Nicotinamide phosphoribosyltransferase (NAMPT) is the key enzyme of the NAD salvage pathway starting from nicotinamide. Cancer cells have an increased demand for NAD due to their high proliferation and DNA repair rate. Consequently, NAMPT is considered as a putative target for anti-cancer therapies. There is evidence that AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) become dysregulated during the development of hepatocellular carcinoma (HCC). Here, we investigated the effects of NAMPT inhibition by its specific inhibitor FK866 on the viability of hepatocarcinoma cells and analyzed the effects of FK866 on the nutrient sensor AMPK and mTOR complex1 (mTORC1) signaling. Results: FK866 markedly decreased NAMPT activity and NAD content in hepatocarcinoma cells (Huh7 cells, Hep3B cells) and led to delayed ATP reduction which was associated with increased cell death. These effects could be abrogated by administration of nicotinamide mononucleotide (NMN), the enzyme product of NAMPT. Our results demonstrated a dysregulation of the AMPK/mTOR pathway in hepatocarcinoma cells compared to non-cancerous hepatocytes with a higher expression of mTOR and a lower AMPKα activation in hepatocarcinoma cells. We found that NAMPT inhibition by FK866 significantly activated AMPKα and inhibited the activation of mTOR and its downstream targets p70S6 kinase and 4E-BP1 in hepatocarcinoma cells. Non-cancerous hepatocytes were less sensitive to FK866 and did not show changes in AMPK/mTOR signaling after FK866 treatment. Conclusion: Taken together, these findings reveal an important role of the NAMPT-mediated NAD salvage pathway in the energy homeostasis of hepatocarcinoma cells and suggest NAMPT inhibition as a potential treatment option for HCC. - Highlights: • FK866 increases cell death in p53-deficient hepatocarcinoma cells. • AMPK/mTOR signaling is dysregulated in hepatocarcinoma cells. • FK866-induced NAMPT inhibition activates AMPK

  3. Deficiency of LKB1 in skeletal muscle prevents AMPK activation and glucose uptake during contraction

    Sakamoto, Kei; McCarthy, Afshan; Smith, Darrin; Green, Kevin A.; Grahame Hardie, D.; Ashworth, Alan; Dario R. Alessi

    2005-01-01

    Recent studies indicate that the LKB1 tumour suppressor protein kinase is the major ‘upstream' activator of the energy sensor AMP-activated protein kinase (AMPK). We have used mice in which LKB1 is expressed at only ∼10% of the normal levels in muscle and most other tissues, or that lack LKB1 entirely in skeletal muscle. Muscle expressing only 10% of the normal level of LKB1 had significantly reduced phosphorylation and activation of AMPKα2. In LKB1-lacking muscle, the basal activity of the A...

  4. Antidiabetic Effect of Salvianolic Acid A on Diabetic Animal Models via AMPK Activation and Mitochondrial Regulation

    Guifen Qiang

    2015-05-01

    Full Text Available Background/Aims: Diabetes mellitus (DM characterized by hyperglycemia contributes to macrovascular and microvascular complications. Salvianolic acid A (SalA is a polyphenolic compound isolated from the root of Salvia miltiorrhiza Bunge, which is a traditional Chinese medicine widely used to treat cardiovascular diseases. However, little is known about its antidiabetic effect. Our study aimed to investigate the in vivo and in vitro antidiabetic effect of SalA and the underlying mechanisms. Methods: Alloxan-induced type 1 diabetic mice and high-fat diet (HFD and low-dose streptozotocin (STZ-induced type 2 diabetic rats received SalA treatment. Blood glucose, oral glucose tolerance test (OGTT, 24-h food and water intake were monitored. In vitro, glucose consumption and uptake were measured in HepG2 cells and L6 myotubes. Mitochondrial function was detected in hepatic and skeletal muscle mitochondria. AMP-activated protein kinase (AMPK and Akt were analyzed by western blot. Results: In both type 1 and type 2 diabetic animals, SalA lowered fasting blood glucose (FBG and fed blood glucose in dose-dependent manner, as well as reduced 24-h food and water intake. In vitro, SalA caused dose-dependent increase in glucose consumption and enhanced glucose uptake. SalA significantly increased ATP production from 10 min to 12 h in HepG2 cells and L6 myotubes. Interestingly, SalA decreased mitochondrial membrane potential (MMP in HepG2 cells. Furthermore, SalA improved hepatic and skeletal muscle mitochondrial function, increased ATP production, and concurrently decreased MMP. In particularly, SalA activated AMPK phosphorylation through Ca2+/calmodulin-dependent protein kinase kinase β (CaMKKβ/AMPK signaling pathway, independent of liver kinase 1 (LKB1/AMPK pathway. However, SalA didn't show any effect on insulin secretagogue and activation of PI3K/Akt signaling pathway. Conclusion: SalA exhibits the antidiabetic effects in diabetic animal models through

  5. LPS inhibits caspase 3-dependent apoptosis in RAW264.7 macrophages induced by the AMPK activator AICAR

    Highlights: • AMPK-activation induces caspase 3-dependent apoptosis in macrophages. • Apoptosis is associated with decreased mTOR and increased p21 levels. • All effects can be significantly inhibited by the TLR4 agonist lipopolysaccharide. - Abstract: AMP-activated kinase is a cellular energy sensor which is activated in stages of increased ATP consumption. Its activation has been associated with a number of beneficial effects such as decreasing inflammatory processes and the disease progress of diabetes and obesity, respectively. Furthermore, AMPK activation has been linked with induction of cell cycle arrest and apoptosis in cancer and vascular cells, indicating that it might have a therapeutic impact for the treatment of cancer and atherosclerosis. However, the impact of AMPK on the proliferation of macrophages, which also play a key role in the formation of atherosclerotic plaques and in inflammatory processes, has not been focused so far. We have assessed the influence of AICAR- and metformin-induced AMPK activation on cell viability of macrophages with and without inflammatory stimulation, respectively. In cells without inflammatory stimulation, we found a strong induction of caspase 3-dependent apoptosis associated with decreased mTOR levels and increased expression of p21. Interestingly, these effects could be inhibited by co-stimulation with bacterial lipopolysaccharide (LPS) but not by other proinflammatory cytokines suggesting that AICAR induces apoptosis via AMPK in a TLR4-pathway dependent manner. In conclusion, our results revealed that AMPK activation is not only associated with positive effects but might also contribute to risk factors by disturbing important features of macrophages. The fact that LPS is able to restore AMPK-associated apoptosis might indicate an important role of TLR4 agonists in preventing unfavorable cell death of immune cells

  6. LPS inhibits caspase 3-dependent apoptosis in RAW264.7 macrophages induced by the AMPK activator AICAR

    Russe, Otto Quintus, E-mail: quintus@russe.eu; Möser, Christine V., E-mail: chmoeser@hotmail.com; Kynast, Katharina L., E-mail: katharina.kynast@googlemail.com; King, Tanya S., E-mail: tanya.sarah.king@googlemail.com; Olbrich, Katrin, E-mail: Katrin.olbrich@gmx.net; Grösch, Sabine, E-mail: groesch@em.uni-frankfurt.de; Geisslinger, Gerd, E-mail: geisslinger@em.uni-frankfurt.de; Niederberger, Ellen, E-mail: e.niederberger@em.uni-frankfurt.de

    2014-05-09

    Highlights: • AMPK-activation induces caspase 3-dependent apoptosis in macrophages. • Apoptosis is associated with decreased mTOR and increased p21 levels. • All effects can be significantly inhibited by the TLR4 agonist lipopolysaccharide. - Abstract: AMP-activated kinase is a cellular energy sensor which is activated in stages of increased ATP consumption. Its activation has been associated with a number of beneficial effects such as decreasing inflammatory processes and the disease progress of diabetes and obesity, respectively. Furthermore, AMPK activation has been linked with induction of cell cycle arrest and apoptosis in cancer and vascular cells, indicating that it might have a therapeutic impact for the treatment of cancer and atherosclerosis. However, the impact of AMPK on the proliferation of macrophages, which also play a key role in the formation of atherosclerotic plaques and in inflammatory processes, has not been focused so far. We have assessed the influence of AICAR- and metformin-induced AMPK activation on cell viability of macrophages with and without inflammatory stimulation, respectively. In cells without inflammatory stimulation, we found a strong induction of caspase 3-dependent apoptosis associated with decreased mTOR levels and increased expression of p21. Interestingly, these effects could be inhibited by co-stimulation with bacterial lipopolysaccharide (LPS) but not by other proinflammatory cytokines suggesting that AICAR induces apoptosis via AMPK in a TLR4-pathway dependent manner. In conclusion, our results revealed that AMPK activation is not only associated with positive effects but might also contribute to risk factors by disturbing important features of macrophages. The fact that LPS is able to restore AMPK-associated apoptosis might indicate an important role of TLR4 agonists in preventing unfavorable cell death of immune cells.

  7. Combined pharmacological activation of AMPK and PPARδ potentiates the effects of exercise in trained mice.

    Manio, Mark Christian C; Inoue, Kazuo; Fujitani, Mina; Matsumura, Shigenobu; Fushiki, Tohru

    2016-03-01

    The combined activation of the cellular energy sensor AMP-activated protein kinase (AMPK) and the nuclear transcription factor peroxisome proliferator-activated receptor delta (PPARδ) has been demonstrated to improve endurance and muscle function by mimicking the effects of exercise training. However, their combined pharmacological activation with exercise training has not been explored. Balb/c mice were trained on a treadmill and administered both the AMPK activator AICAR and the PPARδ agonist GW0742 for 4 weeks. AICAR treatment potentiated endurance, but the combination of AICAR and GW0742 further potentiated endurance and increased all running parameters significantly relative to exercised and nonexercised groups (138-179% and 355% increase in running time, respectively). Despite the lack of change in basal whole-body metabolism, a significant shift to fat as the main energy source with a decline in carbohydrate utilization was observed upon indirect calorimetry analysis at the period near exhaustion. Increased energy substrates before exercise, and elevated muscle nonesterified fatty acids (NEFA) and elevated muscle glycogen at exhaustion were observed together with increased PDK4 mRNA expression. Citrate synthase activity was elevated in AICAR-treated groups, while PGC-1α protein level tended to be increased in GW0742-treated groups. At exhaustion, Pgc1a was robustly upregulated together with Pdk4, Cd36, and Lpl in the muscle. A robust upregulation of Pgc1a and a downregulation in Chrebp were observed in the liver. Our data show that combined pharmacological activation of AMPK and PPARδ potentiates endurance in trained mice by transcriptional changes in muscle and liver, increased available energy substrates, delayed hypoglycemia through glycogen sparing accompanied by increased NEFA availability, and improved substrate shift from carbohydrate to fat. PMID:26997622

  8. Variation in genes coding for AMP-activated protein kinase (AMPK) and breast cancer risk in the European Prospective Investigation on Cancer (EPIC)

    Campa, Daniele; Claus, Rainer; Dostal, Lucie; Stein, Angelika; Chang-Claude, Jenny; Meidtner, Karina; Boeing, Heiner; Olsen, Anja; Tjonneland, Anne; Overvad, Kim; Rodriguez, Laudina; Bonet, Catalina; Sanchez, Maria-Jose; Amiano, Pilar; Huerta, Jose Maria; Barricarte, Aurelio; Khaw, Kay-Tee; Wareham, Nicholas; Travis, Ruth C.; Allen, Naomi E.; Trichopoulou, Antonia; Bamia, Christina; Benetou, Vassiliki; Palli, Domenico; Agnoli, Claudia; Panico, Salvatore; Tumino, Rosario; Sacerdote, Carlotta; van Kranen, Henk; Bueno-de-Mesquita, H. Bas; Peeters, Petra H. M.; van Gils, Carla H.; Lenner, Per; Sund, Malin; Lund, Eiliv; Gram, Inger Torhild; Rinaldi, Sabina; Chajes, Veronique; Romieu, Isabelle; Engel, Pierre; Boutron-Ruault, Marie Christine; Clavel-Chapelon, Francoise; Siddiq, Afshan; Riboli, Elio; Canzian, Federico; Kaaks, Rudolf

    2011-01-01

    AMP-activated protein kinase (AMPK) is an energy sensing/signalling intracellular protein which is activated by an increase in the cellular AMP:ATP ratio after ATP depletion. Once activated, AMPK inhibits fatty acid synthesis and the Akt-mTOR pathway, and activates the p53-p21 axis. All these molecu

  9. Endothelial AMPK activation induces mitochondrial biogenesis and stress adaptation via eNOS-dependent mTORC1 signaling.

    Li, Chunying; Reif, Michaella M; Craige, Siobhan M; Kant, Shashi; Keaney, John F

    2016-05-01

    Metabolic stress sensors like AMP-activated protein kinase (AMPK) are known to confer stress adaptation and promote longevity in lower organisms. This study demonstrates that activating the metabolic stress sensor AMP-activated protein kinase (AMPK) in endothelial cells helps maintain normal cellular function by promoting mitochondrial biogenesis and stress adaptation. To better define the mechanisms whereby AMPK promotes endothelial stress resistance, we used 5-aminoimidazole-4-carboxamide riboside (AICAR) to chronically activate AMPK and observed stimulation of mitochondrial biogenesis in wild type mouse endothelium, but not in endothelium from endothelial nitric oxide synthase knockout (eNOS-null) mice. Interestingly, AICAR-enhanced mitochondrial biogenesis was blocked by pretreatment with the mammalian target of rapamycin complex 1 (mTORC1) inhibitor, rapamycin. Further, AICAR stimulated mTORC1 as determined by phosphorylation of its known downstream effectors in wild type, but not eNOS-null, endothelial cells. Together these data indicate that eNOS is needed to couple AMPK activation to mTORC1 and thus promote mitochondrial biogenesis and stress adaptation in the endothelium. These data suggest a novel mechanism for mTORC1 activation that is significant for investigations in vascular dysfunction. PMID:26989010

  10. In Vivo Correction of COX Deficiency by Activation of the AMPK/PGC-1α Axis

    Viscomi, Carlo; Bottani, Emanuela; Civiletto, Gabriele; Cerutti, Raffaele; Moggio, Maurizio; Fagiolari, Gigliola; Schon, Eric A.; Lamperti, Costanza; Zeviani, Massimo

    2011-01-01

    Summary Increased mitochondrial biogenesis by activation of PPAR- or AMPK/PGC-1α-dependent homeostatic pathways has been proposed as a treatment for mitochondrial disease. We tested this hypothesis on three recombinant mouse models characterized by defective cytochrome c-oxidase (COX) activity: a knockout (KO) mouse for Surf1, a knockout/knockin mouse for Sco2, and a muscle-restricted KO mouse for Cox15. First, we demonstrated that double-recombinant animals overexpressing PGC-1α in skeletal ...

  11. Demethyleneberberine attenuates non-alcoholic fatty liver disease with activation of AMPK and inhibition of oxidative stress.

    Qiang, Xiaoyan; Xu, Lulu; Zhang, Miao; Zhang, Pengcheng; Wang, Yinhang; Wang, Yongchen; Zhao, Zheng; Chen, Huan; Liu, Xie; Zhang, Yubin

    2016-04-15

    Non-alcoholic fatty liver disease (NAFLD) has reached an epidemic level globally, which is recognized to form non-alcoholic steatohepatitis (NASH) by the "two-hit" model, including oxidative stress and inflammation. AMP-activated protein kinase (AMPK) has long been regarded as a key regulator of energy metabolism, which is recognized as a critical target for NAFLD treatment. Here we introduce a natural product, demethyleneberberine (DMB), which potentially ameliorated NAFLD by activating AMPK pathways. Our study showed that the intraperitoneal injection of DMB (20 or 40 mg/kg body weight) decreased hepatic lipid accumulation in methionine and choline deficient (MCD) high-fat diet feeding mice and db/db mice. The further investigation demonstrated that DMB activated AMPK by increasing its phosphorylation in vitro and in vivo. Accompanied with AMPK activation, the expression of lipogenic genes were significantly reduced while genes responsible for the fatty acid β-oxidation were restored in DMB-treated NAFLD mice. In addition, the remarkable oxidative damage and inflammation induced by NAFLD were both attenuated by DMB treatment, which is reflected by decreased lipid oxidative product, malonaldehyde (MDA) and inflammatory factors, tumor necrosis factor α (TNFα) and interleukin 1β (IL-1β). Based on all above, DMB could serve as a novel AMPK activator for treating NAFLD and preventing the pathologic progression from NAFLD to NASH by inhibiting the oxidative stress and inflammation. PMID:26970305

  12. Glucose Enhances Leptin Signaling through Modulation of AMPK Activity

    Haoran Su; Lin Jiang; Christin Carter-Su; Liangyou Rui

    2012-01-01

    Leptin exerts its action by binding to and activating the long form of leptin receptors (LEPRb). LEPRb activates JAK2 that subsequently phosphorylates and activates STAT3. The JAK2/STAT3 pathway is required for leptin control of energy balance and body weight. Defects in leptin signaling lead to leptin resistance, a primary risk factor for obesity. Body weight is also regulated by nutrients, including glucose. Defects in glucose sensing also contribute to obesity. Here we report crosstalk bet...

  13. Astragalus polysaccharides alleviates glucose toxicity and restores glucose homeostasis in diabetic states via activation of AMPK

    Zou, Feng; Mao, Xian-qing; Wang, Nian; Liu, Jian; Ou-Yang, Jing-ping

    2009-01-01

    Aim: To establish the mechanism underlying the improvement of glucose toxicity by Astragalus polysaccharide (APS), which occurred via an AMP activated protein kinase (AMPK)-dependent pathway. Methods: In vivo and in vitro effects of APS on glucose homeostasis were examined in a type 2 diabetes mellitus (T2DM) rat model. The T2DM rat model was duplicated by a high-fat diet (58% fat, 25.6% carbohydrate, and 16.4% protein) and a small dose of streptozotocin (STZ, 25 mg/kg, ip). After APS therapy...

  14. AMP-activated protein kinase (AMPK) cross-talks with canonical Wnt signaling via phosphorylation of β-catenin at Ser 552

    AMP-activated protein kinase (AMPK) is a key regulator of energy metabolism; its activity is regulated by a plethora of physiological conditions, exercises and many anti-diabetic drugs. Recent studies show that AMPK involves in cell differentiation but the underlying mechanism remains undefined. Wingless Int-1 (Wnt)/β-catenin signaling pathway regulates the differentiation of mesenchymal stem cells through enhancing β-catenin/T-cell transcription factor 1 (TCF) mediated transcription. The objective of this study was to determine whether AMPK cross-talks with Wnt/β-catenin signaling through phosphorylation of β-catenin. C3H10T1/2 mesenchymal cells were used. Chemical inhibition of AMPK and the expression of a dominant negative AMPK decreased phosphorylation of β-catenin at Ser 552. The β-catenin/TCF mediated transcription was correlated with AMPK activity. In vitro, pure AMPK phosphorylated β-catenin at Ser 552 and the mutation of Ser 552 to Ala prevented such phosphorylation, which was further confirmed using [γ-32P]ATP autoradiography. In conclusion, AMPK phosphorylates β-catenin at Ser 552, which stabilizes β-catenin, enhances β-catenin/TCF mediated transcription, expanding AMPK from regulation of energy metabolism to cell differentiation and development via cross-talking with the Wnt/β-catenin signaling pathway.

  15. Cadmium induces autophagy through ROS-dependent activation of the LKB1-AMPK signaling in skin epidermal cells

    Cadmium is a toxic heavy metal which is environmentally and occupationally relevant. The mechanisms underlying cadmium-induced autophagy are not yet completely understood. The present study shows that cadmium induces autophagy, as demonstrated by the increase of LC3-II formation and the GFP-LC3 puncta cells. The induction of autophagosomes was directly visualized by electron microscopy in cadmium-exposed skin epidermal cells. Blockage of LKB1 or AMPK by siRNA transfection suppressed cadmium-induced autophagy. Cadmium-induced autophagy was inhibited in dominant-negative AMPK-transfected cells, whereas it was accelerated in cells transfected with the constitutively active form of AMPK. mTOR signaling, a negative regulator of autophagy, was downregulated in cadmium-exposed cells. In addition, cadmium generated reactive oxygen species (ROS) at relatively low levels, and caused poly(ADP-ribose) polymerase-1 (PARP) activation and ATP depletion. Inhibition of PARP by pharmacological inhibitors or its siRNA transfection suppressed ATP reduction and autophagy in cadmium-exposed cells. Furthermore, cadmium-induced autophagy signaling was attenuated by either exogenous addition of catalase and superoxide dismutase, or by overexpression of these enzymes. Consequently, these results suggest that cadmium-mediated ROS generation causes PARP activation and energy depletion, and eventually induces autophagy through the activation of LKB1-AMPK signaling and the down-regulation of mTOR in skin epidermal cells. - Highlights: → Cadmium, a toxic heavy metal, induces autophagic cell death through ROS-dependent activation of the LKB1-AMPK signaling. → Cadmium generates intracellular ROS at low levels and this leads to severe DNA damage and PARP activation, resulting in ATP depletion, which are the upstream events of LKB1-AMPK-mediated autophagy. → This novel finding may contribute to further understanding of cadmium-mediated diseases.

  16. Nootkatone, a characteristic constituent of grapefruit, stimulates energy metabolism and prevents diet-induced obesity by activating AMPK.

    Murase, Takatoshi; Misawa, Koichi; Haramizu, Satoshi; Minegishi, Yoshihiko; Hase, Tadashi

    2010-08-01

    AMP-activated protein kinase (AMPK) is a serine/threonine kinase that is implicated in the control of energy metabolism and is considered to be a molecular target for the suppression of obesity and the treatment of metabolic syndrome. Here, we identified and characterized nootkatone, a constituent of grapefruit, as a naturally occurring AMPK activator. Nootkatone induced an increase in AMPKalpha1 and -alpha2 activity along with an increase in the AMP/ATP ratio and an increase the phosphorylation of AMPKalpha and the downstream target acetyl-CoA carboxylase (ACC), in C(2)C(12) cells. Nootkatone-induced activation of AMPK was possibly mediated both by LKB1 and Ca(2+)/calmodulin-dependent protein kinase kinase. Nootkatone also upregulated PPARgamma coactivator-1alpha in C(2)C(12) cells and C57BL/6J mouse muscle. In addition, administration of nootkatone (200 mg/kg body wt) significantly enhanced AMPK activity, accompanied by LKB1, AMPK, and ACC phosphorylation in the liver and muscle of mice. Whole body energy expenditure evaluated by indirect calorimetry was also increased by nootkatone administration. Long-term intake of diets containing 0.1% to 0.3% (wt/wt) nootkatone significantly reduced high-fat and high-sucrose diet-induced body weight gain, abdominal fat accumulation, and the development of hyperglycemia, hyperinsulinemia, and hyperleptinemia in C57BL/6J mice. Furthermore, endurance capacity, evaluated as swimming time to exhaustion in BALB/c mice, was 21% longer in mice fed 0.2% nootkatone than in control mice. These findings indicate that long-term intake of nootkatone is beneficial toward preventing obesity and improving physical performance and that these effects are due, at least in part, to enhanced energy metabolism through AMPK activation in skeletal muscle and liver. PMID:20501876

  17. The pentacyclic triterpenoid, plectranthoic acid, a novel activator of AMPK induces apoptotic death in prostate cancer cells.

    Akhtar, Nosheen; Syed, Deeba N; Khan, Mohammad Imran; Adhami, Vaqar M; Mirza, Bushra; Mukhtar, Hasan

    2016-01-26

    Epidemiologic studies indicated that diabetics treated with metformin had a lower incidence of cancer than those taking other anti-diabetes drugs. This led to a surge in the efforts for identification of safer and more effective metformin mimetic compounds. The plant Ficus microcarpa is widely used for the treatment of type 2 diabetes in traditional medicine in South Asia. We obtained extracts from this plant and identified a small molecule, plectranthoic acid (PA), with potent 5'AMP-activated kinase (AMPK) activating properties far superior than metformin. AMPK is the central hub of metabolic regulation and a well-studied therapeutic target for metabolic syndrome, type-2 diabetes and cancer. We observed that treatment of prostate cancer (PCa) cells with PA inhibited proliferation and induced G0/G1 phase cell cycle arrest that was associated with up-regulation of cyclin kinase inhibitors p21/CIP1 and p27/KIP1. PA treatment suppressed mTOR/S6K signaling and induced apoptosis in PCa cells in an AMPK-dependent manner. Interestingly, PA-induced autophagy in PCa cells was found to be independent of AMPK activation. Combination studies of PA and metformin demonstrated that metformin had an inhibitory effect on PA-induced AMPK activation and suppressed PA-mediated apoptosis. Given the anti-proliferative role of PA in cancer and its potent anti-hyperglycemic activity, we suggest that PA should be explored further as a novel activator of AMPK for its ultimate use for the prevention of cancers and treatment of type 2 diabetes. PMID:26683363

  18. In vivo correction of COX deficiency by activation of the AMPK/PGC-1α axis.

    Viscomi, Carlo; Bottani, Emanuela; Civiletto, Gabriele; Cerutti, Raffaele; Moggio, Maurizio; Fagiolari, Gigliola; Schon, Eric A; Lamperti, Costanza; Zeviani, Massimo

    2011-07-01

    Increased mitochondrial biogenesis by activation of PPAR- or AMPK/PGC-1α-dependent homeostatic pathways has been proposed as a treatment for mitochondrial disease. We tested this hypothesis on three recombinant mouse models characterized by defective cytochrome c-oxidase (COX) activity: a knockout (KO) mouse for Surf1, a knockout/knockin mouse for Sco2, and a muscle-restricted KO mouse for Cox15. First, we demonstrated that double-recombinant animals overexpressing PGC-1α in skeletal muscle on a Surf1 KO background showed robust induction of mitochondrial biogenesis and increase of mitochondrial respiratory chain activities, including COX. No such effect was obtained by treating both Surf1(-/-) and Cox15(-/-) mice with the pan-PPAR agonist bezafibrate, which instead showed adverse effects in either model. Contrariwise, treatment with the AMPK agonist AICAR led to partial correction of COX deficiency in all three models, and, importantly, significant motor improvement up to normal in the Sco2(KO/KI) mouse. These results open new perspectives for therapy of mitochondrial disease. PMID:21723506

  19. Compound 13, an α1-selective small molecule activator of AMPK, inhibits Helicobacter pylori-induced oxidative stresses and gastric epithelial cell apoptosis

    Half of the world's population experiences Helicobacter pylori (H. pylori) infection, which is a main cause of gastritis, duodenal and gastric ulcer, and gastric cancers. In the current study, we investigated the potential role of compound 13 (C13), a novel α1-selective small molecule activator of AMP-activated protein kinase (AMPK), against H. pylori-induced cytotoxicity in cultured gastric epithelial cells (GECs). We found that C13 induced significant AMPK activation, evidenced by phosphorylation of AMPKα1 and ACC (acetyl-CoA carboxylase), in both primary and transformed GECs. Treatment of C13 inhibited H. pylori-induced GEC apoptosis. AMPK activation was required for C13-mediated GEC protection. Inhibition of AMPK kinase activity by the AMPK inhibitor Compound C, or silencing AMPKα1 expression by targeted-shRNAs, alleviated C13-induced GEC protective activities against H. pylori. Significantly, C13 inhibited H. pylori-induced reactive oxygen species (ROS) production in GECs. C13 induced AMPK-dependent expression of anti-oxidant gene heme oxygenase (HO-1) in GECs. Zinc protoporphyrin (ZnPP) and tin protoporphyrin (SnPP), two HO-1 inhibitors, not only suppressed C13-mediated ROS scavenging activity, but also alleviated its activity in GECs against H. pylori. Together, these results indicate that C13 inhibits H. pylori-induced ROS production and GEC apoptosis through activating AMPK–HO–1 signaling. - Highlights: • We synthesized compound 13 (C13), a α1-selective small molecule AMPK activator. • C13-induced AMPK activation requires α1 subunit in gastric epithelial cells (GECs). • C13 enhances Helicobacter pylori-induced pro-survival AMPK activation to inhibit GEC apoptosis. • C13 inhibits H. pylori-induced reactive oxygen species (ROS) production in GECs. • AMPK-heme oxygenase (HO-1) activation is required for C13-mediated anti-oxidant activity

  20. Compound 13, an α1-selective small molecule activator of AMPK, inhibits Helicobacter pylori-induced oxidative stresses and gastric epithelial cell apoptosis

    Zhao, Hangyong; Zhu, Huanghuang; Lin, Zhou; Lin, Gang; Lv, Guoqiang, E-mail: lvguoqiangwuxivip@163.com

    2015-08-07

    Half of the world's population experiences Helicobacter pylori (H. pylori) infection, which is a main cause of gastritis, duodenal and gastric ulcer, and gastric cancers. In the current study, we investigated the potential role of compound 13 (C13), a novel α1-selective small molecule activator of AMP-activated protein kinase (AMPK), against H. pylori-induced cytotoxicity in cultured gastric epithelial cells (GECs). We found that C13 induced significant AMPK activation, evidenced by phosphorylation of AMPKα1 and ACC (acetyl-CoA carboxylase), in both primary and transformed GECs. Treatment of C13 inhibited H. pylori-induced GEC apoptosis. AMPK activation was required for C13-mediated GEC protection. Inhibition of AMPK kinase activity by the AMPK inhibitor Compound C, or silencing AMPKα1 expression by targeted-shRNAs, alleviated C13-induced GEC protective activities against H. pylori. Significantly, C13 inhibited H. pylori-induced reactive oxygen species (ROS) production in GECs. C13 induced AMPK-dependent expression of anti-oxidant gene heme oxygenase (HO-1) in GECs. Zinc protoporphyrin (ZnPP) and tin protoporphyrin (SnPP), two HO-1 inhibitors, not only suppressed C13-mediated ROS scavenging activity, but also alleviated its activity in GECs against H. pylori. Together, these results indicate that C13 inhibits H. pylori-induced ROS production and GEC apoptosis through activating AMPK–HO–1 signaling. - Highlights: • We synthesized compound 13 (C13), a α1-selective small molecule AMPK activator. • C13-induced AMPK activation requires α1 subunit in gastric epithelial cells (GECs). • C13 enhances Helicobacter pylori-induced pro-survival AMPK activation to inhibit GEC apoptosis. • C13 inhibits H. pylori-induced reactive oxygen species (ROS) production in GECs. • AMPK-heme oxygenase (HO-1) activation is required for C13-mediated anti-oxidant activity.

  1. Region-specific activation of the AMPK system by cocaine: The role of D1 and D2 receptors.

    Xu, Shijie; Kang, Ung Gu

    2016-01-01

    The 5' adenosine monophosphate-activated protein kinase (AMPK) functions as an intracellular energy sensor that regulates and maintains energy balance. The psychostimulant drug cocaine has profound effects on behavior that are accentuated with repeated use, which is a process termed sensitization. Thus, the present study examined whether the sensitizing effects of cocaine could be observed in the AMPK system and aimed to determine whether these effects were mediated by dopamine (DA) D1 or D2 receptors. In the first set of experiments, rats were injected daily for 5days with either cocaine (15mg/kg, intraperitoneal [IP]) or saline. On the day 6, each group was divided into two subgroups and given either cocaine or saline. In the second set of experiments, rats were pretreated with SCH23390 (0.5mg/kg, IP), haloperidol (1mg/kg, IP), or both agents in combination, followed by cocaine or saline treatment. In the drug-naïve state, acute treatment with cocaine produced an increase in locomotor activity and increased AMPK phosphorylation in the frontal cortex but decreased it in the dorsal striatum. In the drug-sensitized state (following repeated treatment), the behavioral responsiveness to cocaine was augmented and accompanied by alterations in AMPK activity. The phosphorylation levels of the upstream kinases Ser-431-LKB1 and Thr-196-CaMK4 were congruent with the changes in AMPK activity. Thr-184/187-TAK1 was phosphorylated after chronic cocaine treatment in the dorsal striatum but not in the frontal cortex. The opposite effects induced by cocaine in the AMPK system in the dorsal striatum and frontal cortex may be explained by the differential activations of DA D1 and D2 receptors in these brain regions. PMID:27132751

  2. Rapamycin requires AMPK activity and p27 expression for promoting autophagy-dependent Tsc2-null cell survival.

    Campos, Tania; Ziehe, Javiera; Fuentes-Villalobos, Francisco; Riquelme, Orlando; Peña, Daniela; Troncoso, Rodrigo; Lavandero, Sergio; Morin, Violeta; Pincheira, Roxana; Castro, Ariel F

    2016-06-01

    Tuberous sclerosis complex (TSC) disease results from inactivation of the TSC1 or TSC2 gene, and is characterized by benign tumors in several organs. Because TSC tumorigenesis correlates with hyperactivation of mTORC1, current therapies focus on mTORC1 inhibition with rapamycin or its analogs. Rapamycin-induced tumor shrinkage has been reported, but tumor recurrence occurs on withdrawal from rapamycin. Autophagy has been associated with development of TSC tumors and with tumor cell survival during rapamycin treatment. mTORC1 and AMPK directly inhibit and activate autophagy, respectively. AMPK is hyperactivated in TSC cells and tumors, and drives cytoplasmic sequestration of the cell-cycle inhibitor p27KIP (p27). Whether AMPK and p27 are involved in rapamycin-induced autophagy and survival of TSC cells remain unexplored. Here, we show that inhibition of AMPK by compound C or by shRNA-mediated depletion of LKB1 reduces activation of autophagy by rapamycin in Tsc2-null cells. Similarly, shRNA-mediated depletion of p27 inhibited rapamycin-induced autophagy. In support of p27 lying downstream of AMPK on the activation of autophagy in Tsc2-null cells, a p27 mutant that preferentially localizes in the cytosol recovered the effect of rapamycin on autophagy in both p27- and LKB1-depleted cells, but a nuclear p27 mutant was inactive. Finally, we show that p27-dependent activation of autophagy is involved in Tsc2-null cell survival under rapamycin treatment. These results indicate that an AMPK/p27 axis is promoting a survival mechanism that could explain in part the relapse of TSC tumors treated with rapamycin, exposing new avenues for designing more efficient treatments for TSC patients. PMID:26975583

  3. Cardiovascular Protective Effect of Metformin and Telmisartan: Reduction of PARP1 Activity via the AMPK-PARP1 Cascade.

    Shang, Fenqing; Zhang, Jiao; Li, Zhao; Zhang, Jin; Yin, Yanjun; Wang, Yaqiong; Marin, Traci L; Gongol, Brendan; Xiao, Han; Zhang, You-Yi; Chen, Zhen; Shyy, John Y-J; Lei, Ting

    2016-01-01

    Hyperglycemia and hypertension impair endothelial function in part through oxidative stress-activated poly (ADP-ribose) polymerase 1 (PARP1). Biguanides and angiotensin II receptor blockers (ARBs) such as metformin and telmisartan have a vascular protective effect. We used cultured vascular endothelial cells (ECs), diabetic and hypertensive rodent models, and AMPKα2-knockout mice to investigate whether metformin and telmisartan have a beneficial effect on the endothelium via AMP-activated protein kinase (AMPK) phosphorylation of PARP1 and thus inhibition of PARP1 activity. The results showed that metformin and telmisartan, but not glipizide and metoprolol, activated AMPK, which phosphorylated PARP1 Ser-177 in cultured ECs and the vascular wall of rodent models. Experiments using phosphorylated/de-phosphorylated PARP1 mutants show that AMPK phosphorylation of PARP1 leads to decreased PARP1 activity and attenuated protein poly(ADP-ribosyl)ation (PARylation), but increased endothelial nitric oxide synthase (eNOS) activity and silent mating type information regulation 2 homolog 1 (SIRT1) expression. Taken together, the data presented here suggest biguanides and ARBs have a beneficial effect on the vasculature by the cascade of AMPK phosphorylation of PARP1 to inhibit PARP1 activity and protein PARylation in ECs, thereby mitigating endothelial dysfunction. PMID:26986624

  4. Cardiovascular Protective Effect of Metformin and Telmisartan: Reduction of PARP1 Activity via the AMPK-PARP1 Cascade.

    Fenqing Shang

    Full Text Available Hyperglycemia and hypertension impair endothelial function in part through oxidative stress-activated poly (ADP-ribose polymerase 1 (PARP1. Biguanides and angiotensin II receptor blockers (ARBs such as metformin and telmisartan have a vascular protective effect. We used cultured vascular endothelial cells (ECs, diabetic and hypertensive rodent models, and AMPKα2-knockout mice to investigate whether metformin and telmisartan have a beneficial effect on the endothelium via AMP-activated protein kinase (AMPK phosphorylation of PARP1 and thus inhibition of PARP1 activity. The results showed that metformin and telmisartan, but not glipizide and metoprolol, activated AMPK, which phosphorylated PARP1 Ser-177 in cultured ECs and the vascular wall of rodent models. Experiments using phosphorylated/de-phosphorylated PARP1 mutants show that AMPK phosphorylation of PARP1 leads to decreased PARP1 activity and attenuated protein poly(ADP-ribosylation (PARylation, but increased endothelial nitric oxide synthase (eNOS activity and silent mating type information regulation 2 homolog 1 (SIRT1 expression. Taken together, the data presented here suggest biguanides and ARBs have a beneficial effect on the vasculature by the cascade of AMPK phosphorylation of PARP1 to inhibit PARP1 activity and protein PARylation in ECs, thereby mitigating endothelial dysfunction.

  5. Flavonoid derivative exerts an antidiabetic effect via AMPK activation in diet-induced obesity mice.

    Chen, Ying; Zhang, Chang; Jin, Mei-Na; Qin, Nan; Qiao, Wei; Yue, Xiao-Long; Duan, Hong-Quan; Niu, Wen-Yan

    2016-09-01

    In our previous study, a derivative of tiliroside, 3-O-[(E)-4-(4-ethoxyphenyl)-2-oxobut-3-en-1-yl]kaempferol (Fla-OEt) significantly enhanced glucose consumption in insulin resistant HepG2 cells. This article deals with the antihyperglycemic and antihyperlipidemic effects of Fla-OEt in diet-induced obesity (DIO) mice. Daily administration of Fla-OEt significantly decreased oral glucose tolerance test, intraperitoneal insulin tolerance test and serum lipids. Hyperinsulinemic-euglycemic clamp and the ratio of high-density-lipoprotein/low-density-lipoprotein with Fla-OEt treatment were increased comparing with high-fat diet (HFD) group, so lipid metabolism was improved. Histopathology examination showed that the Fla-OEt restored the damage of adipose tissues and liver in DIO mice. Moreover, compared with HFD group, Fla-OEt treatment significantly increased the phosphorylation of AMPK and ACC in adiposity tissues, liver, and muscles. The mechanism of its action might be the activation of AMPK pathway. It appears that Fla-OEt is worth further study for development as a lead compound for a potential antidiabetic agent. PMID:26511291

  6. Chronic AMPK activation via loss of FLCN induces functional beige adipose tissue through PGC-1α/ERRα.

    Yan, Ming; Audet-Walsh, Étienne; Manteghi, Sanaz; Rosa Dufour, Catherine; Walker, Benjamin; Baba, Masaya; St-Pierre, Julie; Giguère, Vincent; Pause, Arnim

    2016-05-01

    The tumor suppressor folliculin (FLCN) forms a repressor complex with AMP-activated protein kinase (AMPK). Given that AMPK is a master regulator of cellular energy homeostasis, we generated an adipose-specific Flcn (Adipoq-FLCN) knockout mouse model to investigate the role of FLCN in energy metabolism. We show that loss of FLCN results in a complete metabolic reprogramming of adipose tissues, resulting in enhanced oxidative metabolism. Adipoq-FLCN knockout mice exhibit increased energy expenditure and are protected from high-fat diet (HFD)-induced obesity. Importantly, FLCN ablation leads to chronic hyperactivation of AMPK, which in turns induces and activates two key transcriptional regulators of cellular metabolism, proliferator-activated receptor γ (PPARγ) coactivator-1α (PGC-1α) and estrogen-related receptor α (ERRα). Together, the AMPK/PGC-1α/ERRα molecular axis positively modulates the expression of metabolic genes to promote mitochondrial biogenesis and activity. In addition, mitochondrial uncoupling proteins as well as other markers of brown fat are up-regulated in both white and brown FLCN-null adipose tissues, underlying the increased resistance of Adipoq-FLCN knockout mice to cold exposure. These findings identify a key role of FLCN as a negative regulator of mitochondrial function and identify a novel molecular pathway involved in the browning of white adipocytes and the activity of brown fat. PMID:27151976

  7. Honokiol activates the LKB1–AMPK signaling pathway and attenuates the lipid accumulation in hepatocytes

    Seo, Min Suk; Kim, Jung Hwan; Kim, Hye Jung; Chang, Ki Churl; Park, Sang Won, E-mail: parksw@gnu.ac.kr

    2015-04-15

    Honokiol is a bioactive neolignan compound isolated from the species of Magnolia. This study was designed to elucidate the cellular mechanism by which honokiol alleviates the development of non-alcoholic steatosis. HepG2 cells were treated with honokiol for 1 h, and then exposed to 1 mM free fatty acid (FFA) for 24 h to simulate non-alcoholic steatosis in vitro. C57BL/6 mice were fed with a high-fat diet for 28 days, and honokiol (10 mg/kg/day) was daily treated. Honokiol concentration-dependently attenuated intracellular fat overloading and triglyceride (TG) accumulation in FFA-exposed HepG2 cells. These effects were blocked by pretreatment with an AMP-activated protein kinase (AMPK) inhibitor. Honokiol significantly inhibited sterol regulatory element-binding protein-1c (SREBP-1c) maturation and the induction of lipogenic proteins, stearoyl-CoA desaturase-1 (SCD-1) and fatty acid synthase (FAS) in FFA-exposed HepG2 cells, but these effects were blocked by pretreatment of an AMPK inhibitor. Honokiol induced AMPK phosphorylation and subsequent acetyl-CoA carboxylase (ACC) phosphorylation, which were inhibited by genetic deletion of liver kinase B1 (LKB1). Honokiol stimulated LKB1 phosphorylation, and genetic deletion of LKB1 blocked the effect of honokiol on SREBP-1c maturation and the induction of SCD-1 and FAS proteins in FFA-exposed HepG2 cells. Honokiol attenuated the increases in hepatic TG and lipogenic protein levels and fat accumulation in the mice fed with high-fat diet, while significantly induced LKB1 and AMPK phosphorylation. Taken together, our findings suggest that honokiol has an anti-lipogenic effect in hepatocytes, and this effect may be mediated by the LKB1–AMPK signaling pathway, which induces ACC phosphorylation and inhibits SREBP-1c maturation in hepatocytes. - Highlights: • Honokiol attenuates lipid accumulation induced by free fatty acid in hepatocyte. • Honokiol inhibits the increase in lipogenic enzyme levels induced by free fatty

  8. ETC-1002 regulates immune response, leukocyte homing, and adipose tissue inflammation via LKB1-dependent activation of macrophage AMPK.

    Filippov, Sergey; Pinkosky, Stephen L; Lister, Richard J; Pawloski, Catherine; Hanselman, Jeffrey C; Cramer, Clay T; Srivastava, Rai Ajit K; Hurley, Timothy R; Bradshaw, Cheryl D; Spahr, Mark A; Newton, Roger S

    2013-08-01

    ETC-1002 is an investigational drug currently in Phase 2 development for treatment of dyslipidemia and other cardiometabolic risk factors. In dyslipidemic subjects, ETC-1002 not only reduces plasma LDL cholesterol but also significantly attenuates levels of hsCRP, a clinical biomarker of inflammation. Anti-inflammatory properties of ETC-1002 were further investigated in primary human monocyte-derived macrophages and in in vivo models of inflammation. In cells treated with ETC-1002, increased levels of AMP-activated protein kinase (AMPK) phosphorylation coincided with reduced activity of MAP kinases and decreased production of proinflammatory cytokines and chemokines. AMPK phosphorylation and inhibitory effects of ETC-1002 on soluble mediators of inflammation were significantly abrogated by siRNA-mediated silencing of macrophage liver kinase B1 (LKB1), indicating that ETC-1002 activates AMPK and exerts its anti-inflammatory effects via an LKB1-dependent mechanism. In vivo, ETC-1002 suppressed thioglycollate-induced homing of leukocytes into mouse peritoneal cavity. Similarly, in a mouse model of diet-induced obesity, ETC-1002 restored adipose AMPK activity, reduced JNK phosphorylation, and diminished expression of macrophage-specific marker 4F/80. These data were consistent with decreased epididymal fat-pad mass and interleukin (IL)-6 release by inflamed adipose tissue. Thus, ETC-1002 may provide further clinical benefits for patients with cardiometabolic risk factors by reducing systemic inflammation linked to insulin resistance and vascular complications of metabolic syndrome. PMID:23709692

  9. Compound 13, an α1-selective small molecule activator of AMPK, inhibits Helicobacter pylori-induced oxidative stresses and gastric epithelial cell apoptosis.

    Zhao, Hangyong; Zhu, Huanghuang; Lin, Zhou; Lin, Gang; Lv, Guoqiang

    2015-08-01

    Half of the world's population experiences Helicobacter pylori (H. pylori) infection, which is a main cause of gastritis, duodenal and gastric ulcer, and gastric cancers. In the current study, we investigated the potential role of compound 13 (C13), a novel α1-selective small molecule activator of AMP-activated protein kinase (AMPK), against H. pylori-induced cytotoxicity in cultured gastric epithelial cells (GECs). We found that C13 induced significant AMPK activation, evidenced by phosphorylation of AMPKα1 and ACC (acetyl-CoA carboxylase), in both primary and transformed GECs. Treatment of C13 inhibited H. pylori-induced GEC apoptosis. AMPK activation was required for C13-mediated GEC protection. Inhibition of AMPK kinase activity by the AMPK inhibitor Compound C, or silencing AMPKα1 expression by targeted-shRNAs, alleviated C13-induced GEC protective activities against H. pylori. Significantly, C13 inhibited H. pylori-induced reactive oxygen species (ROS) production in GECs. C13 induced AMPK-dependent expression of anti-oxidant gene heme oxygenase (HO-1) in GECs. Zinc protoporphyrin (ZnPP) and tin protoporphyrin (SnPP), two HO-1 inhibitors, not only suppressed C13-mediated ROS scavenging activity, but also alleviated its activity in GECs against H. pylori. Together, these results indicate that C13 inhibits H. pylori-induced ROS production and GEC apoptosis through activating AMPK-HO-1 signaling. PMID:26022128

  10. Adiponectin Upregulates MiR-133a in Cardiac Hypertrophy through AMPK Activation and Reduced ERK1/2 Phosphorylation.

    Ying Li

    Full Text Available Adiponectin and miR-133a are key regulators in cardiac hypertrophy. However, whether APN has a potential effect on miR-133a remains unclear. In this study, we aimed to investigate whether APN could regulate miR-133a expression in Angiotensin II (Ang II induced cardiac hypertrophy in vivo and in vitro. Lentiviral-mediated adiponectin treatment attenuated cardiac hypertrophy induced by Ang II infusion in male wistar rats as determined by reduced cell surface area and mRNA levels of atrial natriuretic peptide (ANF and brain natriuretic peptide (BNP, also the reduced left ventricular end-diastolic posterior wall thickness (LVPWd and end-diastolic interventricular septal thickness (IVSd. Meanwhile, APN elevated miR-133a level which was downregulated by Ang II. To further investigate the underlying molecular mechanisms, we treated neonatal rat ventricular myocytes (NRVMs with recombinant rat APN before Ang II stimulation. Pretreating cells with recombinant APN promoted AMP-activated protein kinase (AMPK phosphorylation and inhibited ERK activation. By using the inhibitor of AMPK or a lentiviral vector expressing AMPK short hairpin RNA (shRNA cancelled the positive effect of APN on miR-133a. The ERK inhibitor PD98059 reversed the downregulation of miR-133a induced by Ang II. These results indicated that the AMPK activation and ERK inhibition were responsible for the positive effect of APN on miR-133a. Furthermore, adiponectin receptor 1 (AdipoR1 mRNA expression was inhibited by Ang II stimulation. The positive effects of APN on AMPK activation and miR-133a, and the inhibitory effect on ERK phosphorylation were inhibited in NRVMs transfected with lentiviral AdipoR1shRNA. In addition, APN depressed the elevated expression of connective tissue growth factor (CTGF, a direct target of miR-133a, through the AMPK pathway. Taken together, our data indicated that APN reversed miR-133a levels through AMPK activation, reduced ERK1/2 phosphorylation in

  11. Metformin attenuates pressure overload-induced cardiac hypertrophy via AMPK activation

    Yong-nan FU; Han XIAO; Xiao-wei MA; Sheng-yang JIANG; Ming XU; You-yi ZHANG

    2011-01-01

    Aim: To identify the role of metformin in cardiac hypertrophy and investigate the possible mechanism underlying this effect.Methods: Wild type and AMPKα2 knockout (AMPKα2-/-) littermates were subjected to left ventricular pressure overload caused by evaluated using echocardiography and anatomic and histological methods. The antihypertrophic mechanism of metformin was analyzed using Western blotting.Results: Metformin significantly attenuated cardiac hypertrophy induced by pressure overload in wild type mice, but the antihypertrophic actions of metformin were ablated in AMPKx2-/- mice. Furthermore, metformin suppressed the phosphorylation of Akt/protein kinase B (AKT) and mammalian target of rapamycin (mTOR) in response to pressure overload in wild type mice, but not in AMPKα2-/-mice.Conclusion: Long-term administration of metformin may attenuate cardiac hypertrophy induced by pressure overload in nondiabetic mice, and this attenuation is highly dependent on AMPK activation. These findings may provide a potential therapy for patients at risk of developing pathological cardiac hypertrophy.

  12. Metformin, an AMPK activator, stimulates the phosphorylation of aquaporin 2 and urea transporter A1 in inner medullary collecting ducts.

    Klein, Janet D; Wang, Yanhua; Blount, Mitsi A; Molina, Patrick A; LaRocque, Lauren M; Ruiz, Joseph A; Sands, Jeff M

    2016-05-15

    Nephrogenic diabetes insipidus (NDI) is characterized by production of very large quantities of dilute urine due to an inability of the kidney to respond to vasopressin. Congenital NDI results from mutations in the type 2 vasopressin receptor (V2R) in ∼90% of families. These patients do not have mutations in aquaporin-2 (AQP2) or urea transporter UT-A1 (UT-A1). We tested adenosine monophosphate kinase (AMPK) since it is known to phosphorylate another vasopressin-sensitive transporter, NKCC2 (Na-K-2Cl cotransporter). We found AMPK expressed in rat inner medulla (IM). AMPK directly phosphorylated AQP2 and UT-A1 in vitro. Metformin, an AMPK activator, increased phosphorylation of both AQP2 and UT-A1 in rat inner medullary collecting ducts (IMCDs). Metformin increased the apical plasma membrane accumulation of AQP2, but not UT-A1, in rat IM. Metformin increased both osmotic water permeability and urea permeability in perfused rat terminal IMCDs. These findings suggest that metformin increases osmotic water permeability by increasing AQP2 accumulation in the apical plasma membrane but increases urea permeability by activating UT-A1 already present in the membrane. Lastly, metformin increased urine osmolality in mice lacking a V2R, a mouse model of congenital NDI. We conclude that AMPK activation by metformin mimics many of the mechanisms by which vasopressin increases urine-concentrating ability. These findings suggest that metformin may be a novel therapeutic option for congenital NDI due to V2R mutations. PMID:26962099

  13. Diabetes-Related Ankyrin Repeat Protein (DARP/Ankrd23 Modifies Glucose Homeostasis by Modulating AMPK Activity in Skeletal Muscle.

    Yoshiaki Shimoda

    Full Text Available Skeletal muscle is the major site for glucose disposal, the impairment of which closely associates with the glucose intolerance in diabetic patients. Diabetes-related ankyrin repeat protein (DARP/Ankrd23 is a member of muscle ankyrin repeat proteins, whose expression is enhanced in the skeletal muscle under diabetic conditions; however, its role in energy metabolism remains poorly understood. Here we report a novel role of DARP in the regulation of glucose homeostasis through modulating AMP-activated protein kinase (AMPK activity. DARP is highly preferentially expressed in skeletal muscle, and its expression was substantially upregulated during myotube differentiation of C2C12 myoblasts. Interestingly, DARP-/- mice demonstrated better glucose tolerance despite similar body weight, while their insulin sensitivity did not differ from that in wildtype mice. We found that phosphorylation of AMPK, which mediates insulin-independent glucose uptake, in skeletal muscle was significantly enhanced in DARP-/- mice compared to that in wildtype mice. Gene silencing of DARP in C2C12 myotubes enhanced AMPK phosphorylation, whereas overexpression of DARP in C2C12 myoblasts reduced it. Moreover, DARP-silencing increased glucose uptake and oxidation in myotubes, which was abrogated by the treatment with AICAR, an AMPK activator. Of note, improved glucose tolerance in DARP-/- mice was abolished when mice were treated with AICAR. Mechanistically, gene silencing of DARP enhanced protein expression of LKB1 that is a major upstream kinase for AMPK in myotubes in vitro and the skeletal muscle in vivo. Together with the altered expression under diabetic conditions, our data strongly suggest that DARP plays an important role in the regulation of glucose homeostasis under physiological and pathological conditions, and thus DARP is a new therapeutic target for the treatment of diabetes mellitus.

  14. Astragalus polysaccharide stimulates glucose uptake in L6 myotubes through AMPK activation and AS160/TBC1D4 phosphorylation

    Jian LIU; Si-tu YANG; Lang BU; Jing-ping OU-YANG; Jing-fang ZHANG; Jin-zhi LU; De-ling ZHANG; Ke LI; Ke SU; Jing WANG; Ye-min ZHANG; Nian WANG

    2013-01-01

    Aim:To establish the mechanism responsible for the stimulation of glucose uptake by Astragalus polysaccharide (APS),extracted from Astragalus membranaceus Bunge,in L6 myotubes in vitro.Methods:APS-stimulated glucose uptake in L6 myotubes was measured using the 2-deoxy-[3H]-D-glucose method.The adenine nucleotide contents in the cells were measured by HPLC.The phosphorylation of AMP-activated protein kinase (AMPK) and Akt substrate of 160 kDa (AS160) was examined using Western blot analysis.The cells transfected with 4P mutant AS160 (AS160-4P) were constructed using gene transfer approach.Results:Treatment of L6 myotubes with APS (100-1600 μg/mL) significantly increased glucose uptake in time-and concentration-dependent manners.The maximal glucose uptake was reached in the cells treated with APS (400 μg/mL) for 36 h.The APS-stimulated glucose uptake was significantly attenuated by pretreatment with Compound C,a selective AMPK inhibitor or in the cells overexpressing AS160-4P.Treatment of L6 myotubes with APS strongly promoted the activation of AMPK.We further demonstrated that either Ca2+/calmodulin-dependent protein kinase kinase β (CaMKKβ) or liver kinase B1 (LKB1) mediated APS-induced activation of AMPK in L6 myotubes,and the increased cellular AMP:ATP ratio was also involved.Treatment of L6 myotubes with APS robustly enhanced the phosphorylation of AS160,which was significantly attenuated by pretreatment with Compound C.Conclusion:Our results demonstrate that APS stimulates glucose uptake in L6 myotubes through the AMP-AMPK-AS160 pathway,which may contribute to its hypoglycemic effect.

  15. Decreased spontaneous activity in AMPK α2 muscle specific kinase dead mice is not caused by changes in brain dopamine metabolism.

    Møller, Lisbeth L V; Sylow, Lykke; Gøtzsche, Casper R; Serup, Annette K; Christiansen, Søren H; Weikop, Pia; Kiens, Bente; Woldbye, David P D; Richter, Erik A

    2016-10-01

    It is well known that physical activity has several health benefits, yet many people do not exercise. Dopamine levels in the striatum of the brain are thought to be important for the motivation to exercise. Conversely, we hypothesized that muscle quality can affect the motivation to exercise through alterations of the brain dopamine levels specifically in the striatal region. To test this hypothesis, transgenic mice overexpressing an inactivatable dominant negative α2 AMPK construct (AMPK α2 KD) in muscles and littermate wildtype (WT) mice were tested. AMPK α2 KD mice have impaired running capacity and display reduced voluntary wheel running activity. Striatal content of dopamine and its metabolites were measured under basal physiological conditions and after cocaine-induced dopamine efflux from the ventral striatum by in vivo microdialysis. Moreover, cocaine-induced locomotor activity was tested in an open field test. Furthermore, we investigated maximal running capacity and voluntary running over a period of 19days. AMPK α2 KD mice ran 30% less in daily distance compared to WT. Furthermore, AMPK α2 KD mice showed significantly decreased locomotor activity in the open field test compared to WT when treated with saline or cocaine, respectively, but the increase induced by cocaine was similar in AMPK α2 KD and WT mice. The efflux of dopamine in ventral striatum after cocaine treatment increased similarly by 2.5-fold in the two genotypes, and basal levels of dopamine and its metabolites DOPAC and HVA were also similar between genotypes. These findings show that decreased AMPK activity in muscle leads to decreased voluntary activity which is not due to secondary abnormalities in dopamine levels in the ventral striatum or sensitivity to cocaine. Thus, decreased voluntary activity in AMPK muscle deficient mice is most likely unrelated to regulation of brain dopamine content and metabolism. PMID:27306083

  16. Arctigenin Inhibits Adipogenesis by Inducing AMPK Activation and Reduces Weight Gain in High-Fat Diet-Induced Obese Mice.

    Han, Yo-Han; Kee, Ji-Ye; Park, Jinbong; Kim, Hye-Lin; Jeong, Mi-Young; Kim, Dae-Seung; Jeon, Yong-Deok; Jung, Yunu; Youn, Dong-Hyun; Kang, JongWook; So, Hong-Seob; Park, Raekil; Lee, Jong-Hyun; Shin, Soyoung; Kim, Su-Jin; Um, Jae-Young; Hong, Seung-Heon

    2016-09-01

    Although arctigenin (ARC) has been reported to have some pharmacological effects such as anti-inflammation, anti-cancer, and antioxidant, there have been no reports on the anti-obesity effect of ARC. The aim of this study is to investigate whether ARC has an anti-obesity effect and mediates the AMP-activated protein kinase (AMPK) pathway. We investigated the anti-adipogenic effect of ARC using 3T3-L1 pre-adipocytes and human adipose tissue-derived mesenchymal stem cells (hAMSCs). In high-fat diet (HFD)-induced obese mice, whether ARC can inhibit weight gain was investigated. We found that ARC reduced weight gain, fat pad weight, and triglycerides in HFD-induced obese mice. ARC also inhibited the expression of peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein alpha (C/EBPα) in in vitro and in vivo. Furthermore, ARC induced the AMPK activation resulting in down-modulation of adipogenesis-related factors including PPARγ, C/EBPα, fatty acid synthase, adipocyte fatty acid-binding protein, and lipoprotein lipase. This study demonstrates that ARC can reduce key adipogenic factors by activating the AMPK in vitro and in vivo and suggests a therapeutic implication of ARC for obesity treatment. J. Cell. Biochem. 117: 2067-2077, 2016. © 2016 Wiley Periodicals, Inc. PMID:26852013

  17. GPR40 agonist ameliorates liver X receptor-induced lipid accumulation in liver by activating AMPK pathway.

    Li, Meng; Meng, Xiangyu; Xu, Jie; Huang, Xiuqing; Li, Hongxia; Li, Guoping; Wang, Shu; Man, Yong; Tang, Weiqing; Li, Jian

    2016-01-01

    Hepatic steatosis is strongly linked to insulin resistance and type 2 diabetes. GPR40 is a G protein-coupled receptor mediating free fatty acid-induced insulin secretion and thus plays a beneficial role in the improvement of diabetes. However, the impact of GPR40 agonist on hepatic steatosis still remains to be elucidated. In the present study, we found that activation of GPR40 by its agonist GW9508 attenuated Liver X receptor (LXR)-induced hepatic lipid accumulation. Activation of LXR in the livers of C57BL/6 mice fed a high-cholesterol diet and in HepG2 cells stimulated by chemical agonist caused increased expression of its target lipogenic genes and subsequent lipid accumulation. All these effects of LXR were dramatically downregulated after GW9508 supplementation. Moreover, GPR40 activation was accompanied by upregulation of AMPK pathway, whereas the inhibitive effect of GPR40 on the lipogenic gene expression was largely abrogated by AMPK knockdown. Taken together, our results demonstrated that GW9508 exerts a beneficial effect to ameliorate LXR-induced hepatic steatosis through regulation of AMPK signaling pathway. PMID:27121981

  18. GPR40 agonist ameliorates liver X receptor-induced lipid accumulation in liver by activating AMPK pathway

    Li, Meng; Meng, Xiangyu; Xu, Jie; Huang, Xiuqing; Li, Hongxia; Li, Guoping; Wang, Shu; Man, Yong; Tang, Weiqing; Li, Jian

    2016-01-01

    Hepatic steatosis is strongly linked to insulin resistance and type 2 diabetes. GPR40 is a G protein-coupled receptor mediating free fatty acid-induced insulin secretion and thus plays a beneficial role in the improvement of diabetes. However, the impact of GPR40 agonist on hepatic steatosis still remains to be elucidated. In the present study, we found that activation of GPR40 by its agonist GW9508 attenuated Liver X receptor (LXR)-induced hepatic lipid accumulation. Activation of LXR in the livers of C57BL/6 mice fed a high-cholesterol diet and in HepG2 cells stimulated by chemical agonist caused increased expression of its target lipogenic genes and subsequent lipid accumulation. All these effects of LXR were dramatically downregulated after GW9508 supplementation. Moreover, GPR40 activation was accompanied by upregulation of AMPK pathway, whereas the inhibitive effect of GPR40 on the lipogenic gene expression was largely abrogated by AMPK knockdown. Taken together, our results demonstrated that GW9508 exerts a beneficial effect to ameliorate LXR-induced hepatic steatosis through regulation of AMPK signaling pathway. PMID:27121981

  19. Autophagy facilitates lung adenocarcinoma resistance to cisplatin treatment by activation of AMPK/mTOR signaling pathway

    Wu, Tao; Wang, Min-Cong; Jing, Li; Liu, Zhi-Yan; Guo, Hui; Liu, Ying; Bai, Yi-Yang; Cheng, Yang-Zi; Nan, Ke-Jun; Liang, Xuan

    2015-01-01

    Resistance to cisplatin-based therapy is a major challenge in the control of lung cancer progression. However, the underlying mechanisms remain largely unclear. Autophagy is closely associated with resistance to lung cancer therapy, but the function of autophagy in cisplatin treatment is still controversial. Here, we investigated whether autophagy was involved in lung adenocarcinoma resistance to cisplatin and further elucidated the underlying molecular mechanisms. Cisplatin-refractory lung adenocarcinoma cells increased autophagic vacuole formation detected by monodansylcadaverine staining. When exposed to cisplatin, lung adeno-carcinoma cells demonstrated increased levels of autophagy detected by MAP1A/1B LC3B and mammalian homologue of yeast Atg6 (Beclin-1) expression using Western blot analysis. Activation of cisplatin-induced autophagic flux was increased by using chloroquine (CQ), which can accumulate LC3B-II protein and increase punctate distribution of LC3B localization. The combination of cisplatin with CQ was more potent than cisplatin alone in inhibiting lung adenocarcinoma cell growth, which also increased cisplatin-induced apoptosis. Compared to cisplatin treatment alone, the combination of cisplatin and CQ decreased p-AMPK and increased p-mTOR protein expressions, in addition, the AMPK inhibitor Compound C plus cisplatin downregulated p-AMPK and upregulated p-mTOR as well as depressed LC3B cleavage. These findings demonstrate that activation of autophagy is a hallmark of cisplatin exposure in human lung adenocarcinoma cells, and that there is a cisplatin-induced autophagic response via activation of the AMPK/mTOR signaling pathway. We speculate that autophagy can be used as a novel therapeutic target to overcome cisplatin-resistant lung adenocarcinoma. PMID:26715839

  20. Long-Term Consumption of Platycodi Radix Ameliorates Obesity and Insulin Resistance via the Activation of AMPK Pathways.

    Lee, Chae Eun; Hur, Haeng Jeon; Hwang, Jin-Taek; Sung, Mi Jeong; Yang, Hye Jeong; Kim, Hyun-Jin; Park, Jae Ho; Kwon, Dae Young; Kim, Myung-Sunny

    2012-01-01

    This study was designed to evaluate the effects and mechanism of Platycodi radix, having white balloon flower (Platycodon grandiflorum for. albiflorum (Honda) H. Hara) on obesity and insulin resistance. The extracts of Platycodi radix with white balloon flower were tested in cultured cells and administered into mice on a high-fat diet. The Platycodi radix activated the AMPK/ACC phosphorylation in C2C12 myotubes and also suppressed adipocyte differentiation in 3T3-L1 cells. In experimental animal, it suppressed the weight gain of obese mice and ameliorated obesity-induced insulin resistance. It also reduced the elevated circulating mediators, including triglyceride (TG), T-CHO, leptin, resistin, and monocyte chemotactic protein (MCP)-1 in obesity. As shown in C2C12 myotubes, the administration of Platycodi radix extracts also recovered the AMPK/ACC phosphorylation in the muscle of obese mice. These results suggest that Platycodi radix with white balloon flower ameliorates obesity and insulin resistance in obese mice via the activation of AMPK/ACC pathways and reductions of adipocyte differentiation. PMID:22829857

  1. Long-Term Consumption of Platycodi Radix Ameliorates Obesity and Insulin Resistance via the Activation of AMPK Pathways

    Chae Eun Lee

    2012-01-01

    Full Text Available This study was designed to evaluate the effects and mechanism of Platycodi radix, having white balloon flower (Platycodon grandiflorum for. albiflorum (Honda H. Hara on obesity and insulin resistance. The extracts of Platycodi radix with white balloon flower were tested in cultured cells and administered into mice on a high-fat diet. The Platycodi radix activated the AMPK/ACC phosphorylation in C2C12 myotubes and also suppressed adipocyte differentiation in 3T3-L1 cells. In experimental animal, it suppressed the weight gain of obese mice and ameliorated obesity-induced insulin resistance. It also reduced the elevated circulating mediators, including triglyceride (TG, T-CHO, leptin, resistin, and monocyte chemotactic protein (MCP-1 in obesity. As shown in C2C12 myotubes, the administration of Platycodi radix extracts also recovered the AMPK/ACC phosphorylation in the muscle of obese mice. These results suggest that Platycodi radix with white balloon flower ameliorates obesity and insulin resistance in obese mice via the activation of AMPK/ACC pathways and reductions of adipocyte differentiation.

  2. Negative regulation of mTOR activity by LKB1-AMPK signaling in non-small cell lung cancer cells

    Li-xia DONG; Lin-lin SUN; Xia ZHANG; Li PAN; Lin-juan LIAN; Zhe CHEN; Dian-sheng ZHONG

    2013-01-01

    Aim: To investigate the role of LKB1 in regulation of mTOR signaling in non-small cell lung cancer (NSCLC) cells.Methods: LKB1 protein expression and phosphorylation of AMPK,4E-BP1 and S6K in the cells were assessed using Western blotting in various NSCLC cell lines (A549,H460,H1792,Calu-1,and H1299).Energy stress was mimicked by treating the cells with 2-deoxyglucose (2-DG).Compound C was used to inhibit AMPK activity.Cell growth was measured using the MTS assay.Results: LKB1 protein was expressed in LKB1 wild-type Calu-1,H1299,and H1792 cells,but it was undetected in LKB1 mutant A549 and H460 cells.Treatment of the LKB1 wild-type cells with 2-DG (5,10,and 25 mmol/L) augmented the phosphorylation of AMPK in dose-and time-dependent manners.In the LKB1 wild-type cells,2-DG dramatically suppressed the phosphorylation of two mTOR targets,4E-BP1 and S6K,whereas the LKB1 mutant A549 and H460 cells were highly resistant to 2-DG-induced inhibition on mTOR activity.In addition,stable knockdown of LKB1 in H1299 cells impaired 2-DG-induced inhibition on mTOR activity.Pretreatment of H1299 and H1792 cells with the AMPK inhibitor compound C (10 Pmoi/L) blocked 2-DG-induced inhibition on mTOR activity.2-DG inhibited the growth of H1299 cells more effectively than that of H460 cells; stable knockdown of LKB1 in H1299 cells attenuated the growth inhibition caused by 2-DG.Conclusion: In non-small cell lung cancer cells,LKB1/AMPK signaling negatively regulates mTOR activity and contributes to cell growth inhibition in response to energy stress.

  3. AMPK activation represses the human gene promoter of the cardiac isoform of acetyl-CoA carboxylase: Role of nuclear respiratory factor-1

    Research highlights: → AMPK inhibits acetyl-CoA carboxylase beta gene promoter activity. → Nuclear respiratory factor-1 inhibits acetyl-CoA carboxylase beta promoter activity. → AMPK regulates acetyl-CoA carboxylase beta at transcriptional level. -- Abstract: The cardiac-enriched isoform of acetyl-CoA carboxylase (ACCβ) produces malonyl-CoA, a potent inhibitor of carnitine palmitoyltransferase-1. AMPK inhibits ACCβ activity, lowering malonyl-CoA levels and promoting mitochondrial fatty acid β-oxidation. Previously, AMPK increased promoter binding of nuclear respiratory factor-1 (NRF-1), a pivotal transcriptional modulator controlling gene expression of mitochondrial proteins. We therefore hypothesized that NRF-1 inhibits myocardial ACCβ promoter activity via AMPK activation. A human ACCβ promoter-luciferase construct was transiently transfected into neonatal cardiomyocytes ± a NRF-1 expression construct. NRF-1 overexpression decreased ACCβ gene promoter activity by 71 ± 4.6% (p < 0.001 vs. control). Transfections with 5'-end serial promoter deletions revealed that NRF-1-mediated repression of ACCβ was abolished with a pPIIβ-18/+65-Luc deletion construct. AMPK activation dose-dependently reduced ACCβ promoter activity, while NRF-1 addition did not further decrease it. We also investigated NRF-1 inhibition in the presence of upstream stimulatory factor 1 (USF1), a known transactivator of the human ACCβ gene promoter. Here NRF-1 blunted USF1-dependent induction of ACCβ promoter activity by 58 ± 7.5% (p < 0.001 vs. control), reversed with a dominant negative NRF-1 construct. NRF-1 also suppressed endogenous USF1 transcriptional activity by 55 ± 6.2% (p < 0.001 vs. control). This study demonstrates that NRF-1 is a novel transcriptional inhibitor of the human ACCβ gene promoter in the mammalian heart. Our data extends AMPK regulation of ACCβ to the transcriptional level.

  4. Targeting energy metabolic and oncogenic signaling pathways in triple-negative breast cancer by a novel adenosine monophosphate-activated protein kinase (AMPK) activator.

    Lee, Kuen-Haur; Hsu, En-Chi; Guh, Jih-Hwa; Yang, Hsiao-Ching; Wang, Dasheng; Kulp, Samuel K; Shapiro, Charles L; Chen, Ching-Shih

    2011-11-11

    The antitumor activities of the novel adenosine monophosphate-activated protein kinase (AMPK) activator, OSU-53, were assessed in in vitro and in vivo models of triple-negative breast cancer. OSU-53 directly stimulated recombinant AMPK kinase activity (EC(50), 0.3 μM) and inhibited the viability and clonogenic growth of MDA-MB-231 and MDA-MB-468 cells with equal potency (IC(50), 5 and 2 μM, respectively) despite lack of LKB1 expression in MDA-MB-231 cells. Nonmalignant MCF-10A cells, however, were unaffected. Beyond AMPK-mediated effects on mammalian target of rapamycin signaling and lipogenesis, OSU-53 also targeted multiple AMPK downstream pathways. Among these, the protein phosphatase 2A-dependent dephosphorylation of Akt is noteworthy because it circumvents the feedback activation of Akt that results from mammalian target of rapamycin inhibition. OSU-53 also modulated energy homeostasis by suppressing fatty acid biosynthesis and shifting the metabolism to oxidation by up-regulating the expression of key regulators of mitochondrial biogenesis, such as a peroxisome proliferator-activated receptor γ coactivator 1α and the transcription factor nuclear respiratory factor 1. Moreover, OSU-53 suppressed LPS-induced IL-6 production, thereby blocking subsequent Stat3 activation, and inhibited hypoxia-induced epithelial-mesenchymal transition in association with the silencing of hypoxia-inducible factor 1a and the E-cadherin repressor Snail. In MDA-MB-231 tumor-bearing mice, daily oral administration of OSU-53 (50 and 100 mg/kg) suppressed tumor growth by 47-49% and modulated relevant intratumoral biomarkers of drug activity. However, OSU-53 also induced protective autophagy that attenuated its antiproliferative potency. Accordingly, cotreatment with the autophagy inhibitor chloroquine increased the in vivo tumor-suppressive activity of OSU-53. OSU-53 is a potent, orally bioavailable AMPK activator that acts through a broad spectrum of antitumor activities. PMID

  5. Fenofibrate improves renal lipotoxicity through activation of AMPK-PGC-1α in db/db mice.

    Yu Ah Hong

    Full Text Available Peroxisome proliferator-activated receptor (PPAR-α, a lipid-sensing transcriptional factor, serves an important role in lipotoxicity. We evaluated whether fenofibrate has a renoprotective effect by ameliorating lipotoxicity in the kidney. Eight-week-old male C57BLKS/J db/m control and db/db mice, divided into four groups, received fenofibrate for 12 weeks. In db/db mice, fenofibrate ameliorated albuminuria, mesangial area expansion and inflammatory cell infiltration. Fenofibrate inhibited accumulation of intra-renal free fatty acids and triglycerides related to increases in PPARα expression, phosphorylation of AMP-activated protein kinase (AMPK, and activation of Peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α-estrogen-related receptor (ERR-1α-phosphorylated acetyl-CoA carboxylase (pACC, and suppression of sterol regulatory element-binding protein (SREBP-1 and carbohydrate regulatory element-binding protein (ChREBP-1, key downstream effectors of lipid metabolism. Fenofibrate decreased the activity of phosphatidylinositol-3 kinase (PI3K-Akt phosphorylation and FoxO3a phosphorylation in kidneys, increasing the B cell leukaemia/lymphoma 2 (BCL-2/BCL-2-associated X protein (BAX ratio and superoxide dismutase (SOD 1 levels. Consequently, fenofibrate recovered from renal apoptosis and oxidative stress, as reflected by 24 hr urinary 8-isoprostane. In cultured mesangial cells, fenofibrate prevented high glucose-induced apoptosis and oxidative stress through phosphorylation of AMPK, activation of PGC-1α-ERR-1α, and suppression of SREBP-1 and ChREBP-1. Our results suggest that fenofibrate improves lipotoxicity via activation of AMPK-PGC-1α-ERR-1α-FoxO3a signaling, showing its potential as a therapeutic modality for diabetic nephropathy.

  6. AMP-activated protein kinase (AMPK) {beta}1{beta}2 muscle null mice reveal an essential role for AMPK in maintaining mitochondrial content and glucose uptake during exercise

    O'Neill, Hayley M; Maarbjerg, Stine Just; Crane, Justin D;

    2011-01-01

    . Interestingly, young ß1ß2M-KO mice fed a control chow diet are not obese or insulin resistant but do have impaired contraction-stimulated glucose uptake. These data demonstrate an obligatory role for skeletal muscle AMPK in maintaining mitochondrial capacity and contraction-stimulated glucose uptake, findings...

  7. Ultraviolet (UV and Hydrogen Peroxide Activate Ceramide-ER Stress-AMPK Signaling Axis to Promote Retinal Pigment Epithelium (RPE Cell Apoptosis

    Jin Yao

    2013-05-01

    Full Text Available Ultraviolet (UV radiation and reactive oxygen species (ROS impair the physiological functions of retinal pigment epithelium (RPE cells by inducing cell apoptosis, which is the main cause of age-related macular degeneration (AMD. The mechanism by which UV/ROS induces RPE cell death is not fully addressed. Here, we observed the activation of a ceramide-endoplasmic reticulum (ER stress-AMP activated protein kinase (AMPK signaling axis in UV and hydrogen peroxide (H2O2-treated RPE cells. UV and H2O2 induced an early ceramide production, profound ER stress and AMPK activation. Pharmacological inhibitors against ER stress (salubrinal, ceramide production (fumonisin B1 and AMPK activation (compound C suppressed UV- and H2O2-induced RPE cell apoptosis. Conversely, cell permeable short-chain C6 ceramide and AMPK activator AICAR (5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide mimicked UV and H2O2’s effects and promoted RPE cell apoptosis. Together, these results suggest that UV/H2O2 activates the ceramide-ER stress-AMPK signaling axis to promote RPE cell apoptosis.

  8. AMPK regulates metabolism and survival in response to ionizing radiation

    Background and purpose: AMPK is a metabolic sensor and an upstream inhibitor of mTOR activity. AMPK is phosphorylated by ionizing radiation (IR) in an ATM dependent manner, but the cellular consequences of this phosphorylation event have remained unclear. The objective of this study was to assess whether AMPK plays a functional role in regulating cellular responses to IR. Methods: The importance of AMPK expression for radiation responses was investigated using both MEFs (mouse embryo fibroblasts) double knockout for AMPK α1/α2 subunits and human colorectal carcinoma cells (HCT 116) with AMPK α1/α2 shRNA mediated knockdown. Results: We demonstrate here that IR results in phosphorylation of both AMPK and its substrate, ACC. IR moderately stimulated mTOR activity, and this was substantially exacerbated in the absence of AMPK. AMPK was required for IR induced expression of the mTOR inhibitor REDD1, indicating that AMPK restrains mTOR activity through multiple mechanisms. Likewise, cellular metabolism was deregulated following irradiation in the absence of AMPK, as evidenced by a substantial increase in oxygen consumption rates and lactate production. AMPK deficient cells showed impairment of the G1/S cell cycle checkpoint, and were unable to support long-term proliferation during starvation following radiation. Lastly, we show that AMPK proficiency is important for clonogenic survival after radiation during starvation. Conclusions: These data reveal novel functional roles for AMPK in regulating mTOR signaling, cell cycle, survival and metabolic responses to IR.

  9. Specific deletion of AMP-activated protein kinase (α1AMPK in murine oocytes alters junctional protein expression and mitochondrial physiology.

    Michael J Bertoldo

    Full Text Available Oogenesis and folliculogenesis are dynamic processes that are regulated by endocrine, paracrine and autocrine signals. These signals are exchanged between the oocyte and the somatic cells of the follicle. Here we analyzed the role of AMP-activated protein kinase (AMPK, an important regulator of cellular energy homeostasis, by using transgenic mice deficient in α1AMPK specifically in the oocyte. We found a decrease of 27% in litter size was observed in ZP3-α1AMPK-/- (ZP3-KO female mice. Following in vitro fertilization, where conditions are stressful for the oocyte and embryo, ZP3-KO oocytes were 68% less likely to pass the 2-cell stage. In vivo and in cumulus-oocyte complexes, several proteins involved in junctional communication, such as connexin37 and N-cadherin were down-regulated in the absence of α1AMPK. While the two signalling pathways (PKA and MAPK involved in the junctional communication between the cumulus/granulosa cells and the oocyte were stimulated in control oocytes, ZP3-KO oocytes exhibited only low phosphorylation of MAPK or CREB proteins. In addition, MII oocytes deficient in α1AMPK had a 3-fold lower ATP concentration, an increase in abnormal mitochondria, and a decrease in cytochrome C and PGC1α levels, suggesting perturbed energy production by mitochondria. The absence of α1AMPK also induced a reduction in histone deacetylase activity, which was associated with an increase in histone H3 acetylation (K9/K14 residues. Together, the results of the present study suggest that absence of AMPK, modifies oocyte quality through energy processes and oocyte/somatic cell communication. The limited effect observed in vivo could be partly due to a favourable follicle microenvironment where nutrients, growth factors, and adequate cell interaction were present. Whereas in a challenging environment such as that of in vitro culture following IVF, the phenotype is revealed.

  10. AMPK inhibits MTDH expression via GSK3β and SIRT1 activation: potential role in triple negative breast cancer cell proliferation.

    Gollavilli, Paradesi Naidu; Kanugula, Anantha Koteswararao; Koyyada, Rajeswari; Karnewar, Santosh; Neeli, Praveen Kumar; Kotamraju, Srigiridhar

    2015-10-01

    Recent studies have highlighted the involvement of metadherin (MTDH), an oncogenic protein, in promoting cancer progression, metastasis and chemoresistance in many cancers including mammary carcinomas. However, the molecular regulation of MTDH is still not completely understood. In this study we document that AMP activated protein kinase (AMPK) activation-induced anti-proliferative effects are, in part, mediated by inhibiting MTDH expression in MDA-MB-231 and BT-549 triple negative breast cancer (TNBC) cells. 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR), an AMPK activator, caused growth arrest, inhibition of migration and invasion of TNBC cells. Intriguingly, AICAR or metformin treatment resulted in significant downregulation of MTDH expression via inhibiting c-Myc expression. In contrast, treatment of cells with compound C, an inhibitor of AMPK, increased both c-Myc and MTDH expressions in TNBC cells. Also, AMPK activation caused increased glycogen synthase kinase 3β (GSK3β) activity by inhibiting the inactive phosphorylation at Ser9, on the one hand, and activation of sirtuin1 (SIRT1) by inhibiting Ser47 phosphorylation, as evidenced by deacetylation of p53, on the other hand. Moreover, AMPK-induced GSK3β and SIRT1 activities were found to be responsible for inhibiting c-Myc-mediated upregulation of MTDH, as LiCl (an inhibitor of GSK3β) and EX-527 (an inhibitor of SIRT1) reversed AICAR-mediated downregulation of c-Myc and MTDH expressions. Similar results were observed with siSIRT1 treatment. Furthermore, AICAR and EX-527 treatments caused increased cell death under MTDH-depleted conditions. Finally, we uncovered a novel regulation of MTDH expression and showed that AMPK activation by inducing GSK3β and SIRT1 downregulates MTDH expression via inhibiting c-Myc in TNBC cells. PMID:26236947

  11. Decreased spontaneous activity in AMPK α2 muscle specific kinase dead mice is not caused by changes in brain dopamine metabolism

    Møller, Lisbeth Liliendal Valbjørn; Sylow, Lykke; Gøtzsche, Casper René;

    2016-01-01

    It is well known that physical activity has several health benefits, yet many people do not exercise. Dopamine levels in the striatum of the brain are thought to be important for the motivation to exercise. Conversely, we hypothesized that muscle quality can affect the motivation to exercise...... through alterations of the brain dopamine levels specifically in the striatal region. To test this hypothesis, transgenic mice overexpressing an inactivatable dominant negative α2 AMPK construct (AMPK α2 KD) in muscles and littermate wildtype (WT) mice were tested. AMPK α2 KD mice have impaired running...... capacity and display reduced voluntary wheel running activity. Striatal content of dopamine and its metabolites were measured under basal physiological conditions and after cocaine-induced dopamine efflux from the ventral striatum by in vivo microdialysis. Moreover, cocaine-induced locomotor activity was...

  12. Fenoterol inhibits LPS-induced AMPK activation and inflammatory cytokine production through β-arrestin-2 in THP-1 cell line

    The AMP-activated protein kinase (AMPK) pathway is involved in regulating inflammation in several cell lines. We reported that fenoterol, a β2-adrenergic receptor (β2-AR) agonist, had anti-inflammatory effects in THP-1 cells, a monocytic cell line. Whether the fenoterol anti-inflammatory effect involves the AMPK pathway is unknown. In this study, we explored the mechanism of β2-AR stimulation with fenoterol in a lipopolysaccharide (LPS)-induced inflammatory cytokine secretion in THP-1 cells. We studied whether fenoterol and β-arrestin-2 or AMPKα1 subunit knockdown could affect LPS-induced AMPK activation, nuclear factor-kappa B (NF-κB) activation and inflammatory cytokine secretion. LPS-induced AMPK activation and interleukin 1β (IL-1β) release were reduced with fenoterol pretreatment of THP-1 cells. SiRNA knockdown of β-arrestin-2 abolished the fenoterol inhibition of LPS-induced AMPK activation and interleukin 1β (IL-1β) release, thus β-arrestin-2 mediated the anti-inflammatory effects of fenoterol on LPS-treated THP-1 cells. In addition, siRNA knockdown of AMPKα1 significantly attenuated the LPS-induced NF-κB activation and IL-1β release, so AMPKα1 was a key signaling molecule involved in LPS-induced inflammatory cytokine production. These results suggested the β2-AR agonist fenoterol inhibited LPS-induced AMPK activation and IL-1β release via β-arrestin-2 in THP-1 cells. The exploration of these mechanisms may help optimize therapeutic agents targeting these pathways in inflammatory diseases. - Highlights: • β2-AR agonist fenoterol exerts its protective effect on LPS-treated THP-1 cells. • Fenoterol inhibits LPS-induced AMPK activation and IL-1β production. • β-arrestin2 mediates fenoterol-inhibited AMPK activation and IL-1β release. • AMPKα1 is involved in LPS-induced NF-κB activation and IL-1β production

  13. Fenoterol inhibits LPS-induced AMPK activation and inflammatory cytokine production through β-arrestin-2 in THP-1 cell line

    Wang, Wei [Department of Respiratory Medicine, Peking University Third Hospital, Beijing (China); Department of Infectious Diseases, Peking University Third Hospital, Beijing (China); Zhang, Yuan [Department of Respiratory Medicine, Peking University Third Hospital, Beijing (China); Xu, Ming; Zhang, You-Yi [Department of Institute of Vascular Medicine and Beijing Key Laboratory of Cardiovascular Receptors Research, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Peking University Third Hospital, Beijing (China); He, Bei, E-mail: puh3_hb@bjmu.edu.cn [Department of Respiratory Medicine, Peking University Third Hospital, Beijing (China)

    2015-06-26

    The AMP-activated protein kinase (AMPK) pathway is involved in regulating inflammation in several cell lines. We reported that fenoterol, a β{sub 2}-adrenergic receptor (β{sub 2}-AR) agonist, had anti-inflammatory effects in THP-1 cells, a monocytic cell line. Whether the fenoterol anti-inflammatory effect involves the AMPK pathway is unknown. In this study, we explored the mechanism of β{sub 2}-AR stimulation with fenoterol in a lipopolysaccharide (LPS)-induced inflammatory cytokine secretion in THP-1 cells. We studied whether fenoterol and β-arrestin-2 or AMPKα1 subunit knockdown could affect LPS-induced AMPK activation, nuclear factor-kappa B (NF-κB) activation and inflammatory cytokine secretion. LPS-induced AMPK activation and interleukin 1β (IL-1β) release were reduced with fenoterol pretreatment of THP-1 cells. SiRNA knockdown of β-arrestin-2 abolished the fenoterol inhibition of LPS-induced AMPK activation and interleukin 1β (IL-1β) release, thus β-arrestin-2 mediated the anti-inflammatory effects of fenoterol on LPS-treated THP-1 cells. In addition, siRNA knockdown of AMPKα1 significantly attenuated the LPS-induced NF-κB activation and IL-1β release, so AMPKα1 was a key signaling molecule involved in LPS-induced inflammatory cytokine production. These results suggested the β{sub 2}-AR agonist fenoterol inhibited LPS-induced AMPK activation and IL-1β release via β-arrestin-2 in THP-1 cells. The exploration of these mechanisms may help optimize therapeutic agents targeting these pathways in inflammatory diseases. - Highlights: • β{sub 2}-AR agonist fenoterol exerts its protective effect on LPS-treated THP-1 cells. • Fenoterol inhibits LPS-induced AMPK activation and IL-1β production. • β-arrestin2 mediates fenoterol-inhibited AMPK activation and IL-1β release. • AMPKα1 is involved in LPS-induced NF-κB activation and IL-1β production.

  14. Autophagy is not required to sustain exercise and PRKAA1/AMPK activity but is important to prevent mitochondrial damage during physical activity

    Lo Verso, Francesca; Carnio, Silvia; Vainshtein, Anna; Sandri, Marco

    2014-01-01

    Physical activity has been recently documented to play a fundamental physiological role in the regulation of autophagy in several tissues. It has also been reported that autophagy is required for exercise itself and for training-induced adaptations in glucose homeostasis. These autophagy-mediated metabolic improvements are thought to be largely dependent on the activation of the metabolic sensor PRKAA1/AMPK. However, it is unknown whether these important benefits stem from systemic adaptation...

  15. AMPK and Exercise: Glucose Uptake and Insulin Sensitivity

    Hayley M O'Neill

    2013-01-01

    AMPK is an evolutionary conserved sensor of cellular energy status that is activated during exercise. Pharmacological activation of AMPK promotes glucose uptake, fatty acid oxidation, mitochondrial biogenesis, and insulin sensitivity; processes that are reduced in obesity and contribute to the development of insulin resistance. AMPK deficient mouse models have been used to provide direct genetic evidence either supporting or refuting a role for AMPK in regulating these processes. Exercise pro...

  16. AMP-activated protein kinase inhibits alkaline pH- and PKA-induced apical vacuolar H+-ATPase accumulation in epididymal clear cells.

    Hallows, Kenneth R; Alzamora, Rodrigo; Li, Hui; Gong, Fan; Smolak, Christy; Neumann, Dietbert; Pastor-Soler, Núria M

    2009-04-01

    Acidic luminal pH and low [HCO(3)(-)] maintain sperm quiescent during maturation in the epididymis. The vacuolar H(+)-ATPase (V-ATPase) in clear cells is a major contributor to epididymal luminal acidification. We have shown previously that protein kinase A (PKA), acting downstream of soluble adenylyl cyclase stimulation by alkaline luminal pH or HCO(3)(-), induces V-ATPase apical membrane accumulation in clear cells. Here we examined whether the metabolic sensor AMP-activated protein kinase (AMPK) regulates this PKA-induced V-ATPase apical membrane accumulation. Immunofluorescence labeling of rat and non-human primate epididymides revealed specific AMPK expression in epithelial cells. Immunofluorescence labeling of rat epididymis showed that perfusion in vivo with the AMPK activators 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR) or A-769662 induced a redistribution of the V-ATPase into subapical vesicles, even in the presence of a luminal alkaline (pH 7.8) buffer compared with that of controls perfused without drug. Moreover, preperfusion with AICAR blocked the PKA-mediated V-ATPase translocation to clear cell apical membranes induced by N(6)-monobutyryl-cAMP (6-MB-cAMP). Purified PKA and AMPK both phosphorylated V-ATPase A subunit in vitro. In HEK-293 cells [(32)P]orthophosphate in vivo labeling of the A subunit increased following PKA stimulation and decreased following RNA interference-mediated knockdown of AMPK. Finally, the extent of PKA-dependent in vivo phosphorylation of the A subunit increased with AMPK knockdown. In summary, our findings suggest that AMPK inhibits PKA-mediated V-ATPase apical accumulation in epididymal clear cells, that both kinases directly phosphorylate the V-ATPase A subunit in vitro and in vivo, and that AMPK inhibits PKA-dependent phosphorylation of this subunit. V-ATPase activity may be coupled to the sensing of acid-base status via PKA and to metabolic status via AMPK. PMID:19211918

  17. Wedelolactone Regulates Lipid Metabolism and Improves Hepatic Steatosis Partly by AMPK Activation and Up-Regulation of Expression of PPARα/LPL and LDLR.

    Yun Zhao

    Full Text Available Hyperlipidemia is considered one of the greatest risk factors of cardiovascular diseases. We investigated the anti-hyperlipidemic effect and the underlying mechanism of wedelolactone, a plant-derived coumestan, in HepG2 cells and high-fat diet (HFD-induced hyperlipidemic hamsters. We showed that in cultured HepG2 cells, wedelolactone up-regulated protein levels of adenosine monophosphate activated protein kinase (AMPK and peroxisome proliferator-activated receptor-alpha (PPARα as well as the gene expression of AMPK, PPARα, lipoprotein lipase (LPL, and the low-density lipoprotein receptor (LDLR. Meanwhile, administration of wedelolactone for 4 weeks decreased the lipid profiles of plasma and liver in HFD-induced hyperlipidemic hamsters, including total cholesterol (TC, triglycerides (TG, and low-density lipoprotein-cholesterol (LDL-C. The activation of AMPK and up-regulation of PPARα was also observed with wedelolactone treatment. Furthermore, wedelolactone also increased the activities of superoxidase dismutase (SOD and glutathione peroxidase (GSH-Px and decreased the level of the lipid peroxidation product malondialdehyde (MDA in the liver, therefore decreasing the activity of alanine aminotransferase (ALT. In conclusion, we provide novel experimental evidence that wedelolactone possesses lipid-lowering and steatosis-improving effects, and the underlying mechanism is, at least in part, mediated by the activation of AMPK and the up-regulation of PPARα/LPL and LDLR.

  18. Anti-Diabetic Activities of Jiaotaiwan in db/db Mice by Augmentation of AMPK Protein Activity and Upregulation of GLUT4 Expression

    Na Hu

    2013-01-01

    Full Text Available Jiaotaiwan (JTW, which is composed of Coptis chinensis (CC and cinnamon (CIN, is one of the most well-known traditional Chinese medicines. In this study, we investigated the antidiabetic effects and mechanism of JTW in db/db mice. Results showed that JTW significantly decreased the level of fasting blood glucose and improved glucose and insulin tolerance better than CC or CIN alone. JTW also effectively protected the pancreatic islet shape, augmented the activation of AMP-activated protein kinase (AMPK in the liver, and increased the expression of glucose transporter 4 (GLUT4 protein in skeletal muscle and white fat. AMPK and GLUT4 contributed to glucose metabolism regulation and had an essential function in the development of diabetes mellitus (DM. Therefore, the mechanisms of JTW may be related to suppressing gluconeogenesis by activating AMPK in the liver and affecting glucose uptake in surrounding tissues through the upregulation of GLUT4 protein expression. These findings provided a new insight into the antidiabetic clinical applications of JTW and demonstrated the potential of JTW as a new drug candidate for DM treatment.

  19. AMPK-mediated AS160 phosphorylation in skeletal muscle is dependent on AMPK catalytic and regulatory subunits

    Treebak, Jonas Thue; Glund, Stephan; Deshmukh, Atul;

    2006-01-01

    signaling to glucose uptake. We show that AICAR increases AMPK, acetyl-CoA carboxylase, and AS160 phosphorylation by insulin-independent mechanisms in isolated skeletal muscle. Recombinant AMPK heterotrimeric complexes (a1ß1¿1 and a2ß2¿1) phosphorylate AS160 in a cell-free assay. In mice deficient in AMPK...... signaling (a2 AMPK knockout [KO], a2 AMPK kinase dead [KD], and ¿3 AMPK KO), AICAR effects on AS160 phosphorylation were severely blunted, highlighting that complexes containing a2 and ¿3 are necessary for AICAR-stimulated AS160 phosphorylation in intact skeletal muscle. Contraction-mediated AS160......AMP-activated protein kinase (AMPK) is a heterotrimeric protein that regulates glucose transport mediated by cellular stress or pharmacological agonists such as 5-aminoimidazole-4-carboxamide 1 ß-D-ribonucleoside (AICAR). AS160, a Rab GTPase-activating protein, provides a mechanism linking AMPK...

  20. AMPK activation represses the human gene promoter of the cardiac isoform of acetyl-CoA carboxylase: Role of nuclear respiratory factor-1

    Adam, Tasneem; Opie, Lionel H. [Hatter Cardiovascular Research Institute, Faculty of Health Sciences, University of Cape Town, Observatory 7925 (South Africa); Essop, M. Faadiel, E-mail: mfessop@sun.ac.za [Cardio-Metabolic Research Group (CMRG), Department of Physiological Sciences, Stellenbosch University, Stellenbosch 7600 (South Africa)

    2010-07-30

    Research highlights: {yields} AMPK inhibits acetyl-CoA carboxylase beta gene promoter activity. {yields} Nuclear respiratory factor-1 inhibits acetyl-CoA carboxylase beta promoter activity. {yields} AMPK regulates acetyl-CoA carboxylase beta at transcriptional level. -- Abstract: The cardiac-enriched isoform of acetyl-CoA carboxylase (ACC{beta}) produces malonyl-CoA, a potent inhibitor of carnitine palmitoyltransferase-1. AMPK inhibits ACC{beta} activity, lowering malonyl-CoA levels and promoting mitochondrial fatty acid {beta}-oxidation. Previously, AMPK increased promoter binding of nuclear respiratory factor-1 (NRF-1), a pivotal transcriptional modulator controlling gene expression of mitochondrial proteins. We therefore hypothesized that NRF-1 inhibits myocardial ACC{beta} promoter activity via AMPK activation. A human ACC{beta} promoter-luciferase construct was transiently transfected into neonatal cardiomyocytes {+-} a NRF-1 expression construct. NRF-1 overexpression decreased ACC{beta} gene promoter activity by 71 {+-} 4.6% (p < 0.001 vs. control). Transfections with 5'-end serial promoter deletions revealed that NRF-1-mediated repression of ACC{beta} was abolished with a pPII{beta}-18/+65-Luc deletion construct. AMPK activation dose-dependently reduced ACC{beta} promoter activity, while NRF-1 addition did not further decrease it. We also investigated NRF-1 inhibition in the presence of upstream stimulatory factor 1 (USF1), a known transactivator of the human ACC{beta} gene promoter. Here NRF-1 blunted USF1-dependent induction of ACC{beta} promoter activity by 58 {+-} 7.5% (p < 0.001 vs. control), reversed with a dominant negative NRF-1 construct. NRF-1 also suppressed endogenous USF1 transcriptional activity by 55 {+-} 6.2% (p < 0.001 vs. control). This study demonstrates that NRF-1 is a novel transcriptional inhibitor of the human ACC{beta} gene promoter in the mammalian heart. Our data extends AMPK regulation of ACC{beta} to the transcriptional level.

  1. AMP-Activated Kinase (AMPK Activation by AICAR in Human White Adipocytes Derived from Pericardial White Adipose Tissue Stem Cells Induces a Partial Beige-Like Phenotype.

    Omar Abdul-Rahman

    Full Text Available Beige adipocytes are special cells situated in the white adipose tissue. Beige adipocytes, lacking thermogenic cues, morphologically look quite similar to regular white adipocytes, but with a markedly different response to adrenalin. White adipocytes respond to adrenergic stimuli by enhancing lipolysis, while in beige adipocytes adrenalin induces mitochondrial biogenesis too. A key step in the differentiation and function of beige adipocytes is the deacetylation of peroxisome proliferator-activated receptor (PPARγ by SIRT1 and the consequent mitochondrial biogenesis. AMP-activated protein kinase (AMPK is an upstream activator of SIRT1, therefore we set out to investigate the role of AMPK in beige adipocyte differentiation using human adipose-derived mesenchymal stem cells (hADMSCs from pericardial adipose tissue. hADMSCs were differentiated to white and beige adipocytes and the differentiation medium of the white adipocytes was supplemented with 100 μM [(2R,3S,4R,5R-5-(4-Carbamoyl-5-aminoimidazol-1-yl-3,4-dihydroxyoxolan-2-yl]methyl dihydrogen phosphate (AICAR, a known activator of AMPK. The activation of AMPK with AICAR led to the appearance of beige-like morphological properties in differentiated white adipocytes. Namely, smaller lipid droplets appeared in AICAR-treated white adipocytes in a similar fashion as in beige cells. Moreover, in AICAR-treated white adipocytes the mitochondrial network was more fused than in white adipocytes; a fused mitochondrial system was characteristic to beige adipocytes. Despite the morphological similarities between AICAR-treated white adipocytes and beige cells, functionally AICAR-treated white adipocytes were similar to white adipocytes. We were unable to detect increases in basal or cAMP-induced oxygen consumption rate (a marker of mitochondrial biogenesis when comparing control and AICAR-treated white adipocytes. Similarly, markers of beige adipocytes such as TBX1, UCP1, CIDEA, PRDM16 and TMEM26 remained

  2. AMP-Activated Kinase (AMPK) Activation by AICAR in Human White Adipocytes Derived from Pericardial White Adipose Tissue Stem Cells Induces a Partial Beige-Like Phenotype

    Abdul-Rahman, Omar; Kristóf, Endre; Doan-Xuan, Quang-Minh; Vida, András; Nagy, Lilla; Horváth, Ambrus; Simon, József; Maros, Tamás; Szentkirályi, István; Palotás, Lehel; Debreceni, Tamás; Csizmadia, Péter; Szerafin, Tamás; Fodor, Tamás; Szántó, Magdolna; Tóth, Attila; Kiss, Borbála; Bacsó, Zsolt; Bai, Péter

    2016-01-01

    Beige adipocytes are special cells situated in the white adipose tissue. Beige adipocytes, lacking thermogenic cues, morphologically look quite similar to regular white adipocytes, but with a markedly different response to adrenalin. White adipocytes respond to adrenergic stimuli by enhancing lipolysis, while in beige adipocytes adrenalin induces mitochondrial biogenesis too. A key step in the differentiation and function of beige adipocytes is the deacetylation of peroxisome proliferator-activated receptor (PPARγ) by SIRT1 and the consequent mitochondrial biogenesis. AMP-activated protein kinase (AMPK) is an upstream activator of SIRT1, therefore we set out to investigate the role of AMPK in beige adipocyte differentiation using human adipose-derived mesenchymal stem cells (hADMSCs) from pericardial adipose tissue. hADMSCs were differentiated to white and beige adipocytes and the differentiation medium of the white adipocytes was supplemented with 100 μM [(2R,3S,4R,5R)-5-(4-Carbamoyl-5-aminoimidazol-1-yl)-3,4-dihydroxyoxolan-2-yl]methyl dihydrogen phosphate (AICAR), a known activator of AMPK. The activation of AMPK with AICAR led to the appearance of beige-like morphological properties in differentiated white adipocytes. Namely, smaller lipid droplets appeared in AICAR-treated white adipocytes in a similar fashion as in beige cells. Moreover, in AICAR-treated white adipocytes the mitochondrial network was more fused than in white adipocytes; a fused mitochondrial system was characteristic to beige adipocytes. Despite the morphological similarities between AICAR-treated white adipocytes and beige cells, functionally AICAR-treated white adipocytes were similar to white adipocytes. We were unable to detect increases in basal or cAMP-induced oxygen consumption rate (a marker of mitochondrial biogenesis) when comparing control and AICAR-treated white adipocytes. Similarly, markers of beige adipocytes such as TBX1, UCP1, CIDEA, PRDM16 and TMEM26 remained the same when

  3. Adiponectin enhances osteogenic differentiation in human adipose-derived stem cells by activating the APPL1-AMPK signaling pathway

    Chen, Tong; Wu, Yu-wei; Lu, Hui; Guo, Yuan [Second Dental Center, Peking University School and Hospital of Stomatology, Beijing (China); National Engineering Laboratory for Digital and Material Technology of Stomatology, Peking University School and Hospital of Stomatology, Beijing (China); Tang, Zhi-hui, E-mail: tang_zhihui@live.cn [Second Dental Center, Peking University School and Hospital of Stomatology, Beijing (China); National Engineering Laboratory for Digital and Material Technology of Stomatology, Peking University School and Hospital of Stomatology, Beijing (China)

    2015-05-29

    Human adipose-derived stem cells (hASCs) are multipotent progenitor cells with multi-lineage differentiation potential including osteogenesis and adipogenesis. While significant progress has been made in understanding the transcriptional control of hASC fate, little is known about how hASC differentiation is regulated by the autocrine loop. The most abundant adipocytokine secreted by adipocytes, adiponectin (APN) plays a pivotal role in glucose metabolism and energy homeostasis. Growing evidence suggests a positive association between APN and bone formation yet little is known regarding the direct effects of APN on hASC osteogenesis. Therefore, this study was designed to investigate the varied osteogenic effects and regulatory mechanisms of APN in the osteogenic commitment of hASCs. We found that APN enhanced the expression of osteoblast-related genes in hASCs, such as osteocalcin, alkaline phosphatase, and runt-related transcription factor-2 (Runx2, also known as CBFa1), in a dose- and time-dependent manner. This was further confirmed by the higher expression levels of alkaline phosphatase and increased formation of mineralization nodules, along with the absence of inhibition of cell proliferation. Importantly, APN at 1 μg/ml was the optimal concentration, resulting in maximum deposition of calcium nodules, and was significant superior to bone morphogenetic protein 2. Mechanistically, we found for the first time that APN increased nuclear translocation of the leucine zipper motif (APPL)-1 as well as AMP-activated protein kinase (AMPK) phosphorylation, which were reversed by pretreatment with APPL1 siRNA. Our results indicate that APN promotes the osteogenic differentiation of hASCs by activating APPL1-AMPK signaling, suggesting that manipulation of APN is a novel therapeutic target for controlling hASC fate. - Highlights: • Adiponectin enhances osteogenic differentiation in human adipose-derived stem cells. • The knock-down of APPL1 block the enhancement of

  4. Adiponectin enhances osteogenic differentiation in human adipose-derived stem cells by activating the APPL1-AMPK signaling pathway

    Human adipose-derived stem cells (hASCs) are multipotent progenitor cells with multi-lineage differentiation potential including osteogenesis and adipogenesis. While significant progress has been made in understanding the transcriptional control of hASC fate, little is known about how hASC differentiation is regulated by the autocrine loop. The most abundant adipocytokine secreted by adipocytes, adiponectin (APN) plays a pivotal role in glucose metabolism and energy homeostasis. Growing evidence suggests a positive association between APN and bone formation yet little is known regarding the direct effects of APN on hASC osteogenesis. Therefore, this study was designed to investigate the varied osteogenic effects and regulatory mechanisms of APN in the osteogenic commitment of hASCs. We found that APN enhanced the expression of osteoblast-related genes in hASCs, such as osteocalcin, alkaline phosphatase, and runt-related transcription factor-2 (Runx2, also known as CBFa1), in a dose- and time-dependent manner. This was further confirmed by the higher expression levels of alkaline phosphatase and increased formation of mineralization nodules, along with the absence of inhibition of cell proliferation. Importantly, APN at 1 μg/ml was the optimal concentration, resulting in maximum deposition of calcium nodules, and was significant superior to bone morphogenetic protein 2. Mechanistically, we found for the first time that APN increased nuclear translocation of the leucine zipper motif (APPL)-1 as well as AMP-activated protein kinase (AMPK) phosphorylation, which were reversed by pretreatment with APPL1 siRNA. Our results indicate that APN promotes the osteogenic differentiation of hASCs by activating APPL1-AMPK signaling, suggesting that manipulation of APN is a novel therapeutic target for controlling hASC fate. - Highlights: • Adiponectin enhances osteogenic differentiation in human adipose-derived stem cells. • The knock-down of APPL1 block the enhancement of

  5. Metformin inhibition of mTORC1 activation, DNA synthesis and proliferation in pancreatic cancer cells: Dependence on glucose concentration and role of AMPK

    Sinnett-Smith, James; Kisfalvi, Krisztina; Kui, Robert [Division of Digestive Diseases, Department of Medicine, CURE: Digestive Diseases Research Center, David Geffen School of Medicine and Molecular Biology Institute, University of California at Los Angeles, CA (United States); Rozengurt, Enrique, E-mail: erozengurt@mednet.ucla.edu [Division of Digestive Diseases, Department of Medicine, CURE: Digestive Diseases Research Center, David Geffen School of Medicine and Molecular Biology Institute, University of California at Los Angeles, CA (United States)

    2013-01-04

    Highlights: Black-Right-Pointing-Pointer Metformin inhibits cancer cell growth but the mechanism(s) are not understood. Black-Right-Pointing-Pointer We show that the potency of metformin is sharply dependent on glucose in the medium. Black-Right-Pointing-Pointer AMPK activation was enhanced in cancer cells incubated in physiological glucose. Black-Right-Pointing-Pointer Reciprocally, metformin potently inhibited mTORC1, DNA synthesis and proliferation. Black-Right-Pointing-Pointer Metformin, at low concentrations, inhibited DNA synthesis through AMPK. -- Abstract: Metformin, a widely used anti-diabetic drug, is emerging as a potential anticancer agent but the mechanisms involved remain incompletely understood. Here, we demonstrate that the potency of metformin induced AMPK activation, as shown by the phosphorylation of its substrates acetyl-CoA carboxylase (ACC) at Ser{sup 79} and Raptor at Ser{sup 792}, was dramatically enhanced in human pancreatic ductal adenocarcinoma (PDAC) cells PANC-1 and MiaPaCa-2 cultured in medium containing physiological concentrations of glucose (5 mM), as compared with parallel cultures in medium with glucose at 25 mM. In physiological glucose, metformin inhibited mTORC1 activation, DNA synthesis and proliferation of PDAC cells stimulated by crosstalk between G protein-coupled receptors and insulin/IGF signaling systems, at concentrations (0.05-0.1 mM) that were 10-100-fold lower than those used in most previous reports. Using siRNA-mediated knockdown of the {alpha}{sub 1} and {alpha}{sub 2} catalytic subunits of AMPK, we demonstrated that metformin, at low concentrations, inhibited DNA synthesis through an AMPK-dependent mechanism. Our results emphasize the importance of using medium containing physiological concentrations of glucose to elucidate the anticancer mechanism of action of metformin in pancreatic cancer cells and other cancer cell types.

  6. Metformin inhibition of mTORC1 activation, DNA synthesis and proliferation in pancreatic cancer cells: Dependence on glucose concentration and role of AMPK

    Highlights: ► Metformin inhibits cancer cell growth but the mechanism(s) are not understood. ► We show that the potency of metformin is sharply dependent on glucose in the medium. ► AMPK activation was enhanced in cancer cells incubated in physiological glucose. ► Reciprocally, metformin potently inhibited mTORC1, DNA synthesis and proliferation. ► Metformin, at low concentrations, inhibited DNA synthesis through AMPK. -- Abstract: Metformin, a widely used anti-diabetic drug, is emerging as a potential anticancer agent but the mechanisms involved remain incompletely understood. Here, we demonstrate that the potency of metformin induced AMPK activation, as shown by the phosphorylation of its substrates acetyl-CoA carboxylase (ACC) at Ser79 and Raptor at Ser792, was dramatically enhanced in human pancreatic ductal adenocarcinoma (PDAC) cells PANC-1 and MiaPaCa-2 cultured in medium containing physiological concentrations of glucose (5 mM), as compared with parallel cultures in medium with glucose at 25 mM. In physiological glucose, metformin inhibited mTORC1 activation, DNA synthesis and proliferation of PDAC cells stimulated by crosstalk between G protein-coupled receptors and insulin/IGF signaling systems, at concentrations (0.05–0.1 mM) that were 10–100-fold lower than those used in most previous reports. Using siRNA-mediated knockdown of the α1 and α2 catalytic subunits of AMPK, we demonstrated that metformin, at low concentrations, inhibited DNA synthesis through an AMPK-dependent mechanism. Our results emphasize the importance of using medium containing physiological concentrations of glucose to elucidate the anticancer mechanism of action of metformin in pancreatic cancer cells and other cancer cell types.

  7. Activation of autophagy in human skeletal muscle is dependent on exercise intensity and AMPK activation.

    Schwalm, Céline; Jamart, Cécile; Benoit, Nicolas; Naslain, Damien; Prémont, Christophe; Prévet, Jérémy; Van Thienen, Ruud; Deldicque, Louise; Francaux, Marc

    2015-08-01

    In humans, nutrient deprivation and extreme endurance exercise both activate autophagy. We hypothesized that cumulating fasting and cycling exercise would potentiate activation of autophagy in skeletal muscle. Well-trained athletes were divided into control (n = 8), low-intensity (LI, n = 8), and high-intensity (HI, n = 7) exercise groups and submitted to fed and fasting sessions. Muscle biopsy samples were obtained from the vastus lateralis before, at the end, and 1 h after a 2 h LI or HI bout of exercise. Phosphorylation of ULK1(Ser317) was higher after exercise (P diet. PMID:25957282

  8. Combretum lanceolatum flowers extract shows antidiabetic activity through activation of AMPK by quercetin

    Carlos Roberto Porto Dechandt

    2012-01-01

    Full Text Available The present study evaluated the antidiabetic activity of the Combretum lanceolatum Pohl ex Eichler, Combretaceae, flowers extract (ClEtOH in diabetic rats. Streptozotocin-diabetic rats were divided into four groups: diabetic control, diabetic treated with 500 mg/kg of metformin and diabetic treated with 250 or 500 mg/kg of ClEtOH for 21 days. The treatment of diabetic rats with 500 mg/kg of ClEtOH promoted an increase in the weight of liver, white adipose tissues and skeletal muscles, improving body weight gain. Diabetic rats treated with 500 mg/kg of ClEtOH also presented reduction in glycemia, glycosuria and urinary urea levels, and increase in liver glycogen content. HPLC chromatogram showed that quercetin is the major compound in the extract. The phosphorylation levels of adenosine monophosphate-activated protein kinase were increased in liver slices incubated in vitro with 50 µg/mL of ClEtOH, similarly to the incubation with metformin (50 µg/mL or quercetin (10 µg/mL. The antihyperglycemic effect of ClEtOH was similar to that of metformin and appears to be through inhibition of gluconeogenesis, since urinary urea was reduced and skeletal muscle mass was increased. These data indicate that the antidiabetic activity of the Combretum lanceolatum extract could be mediated, at least in part, through activation of adenosine monophosphateactivated protein kinase by quercetin.

  9. Combretum lanceolatum flowers extract shows antidiabetic activity through activation of AMPK by quercetin

    Carlos Roberto Porto Dechandt

    2013-04-01

    Full Text Available The present study evaluated the antidiabetic activity of the Combretum lanceolatum Pohl ex Eichler, Combretaceae, flowers extract (ClEtOH in diabetic rats. Streptozotocin-diabetic rats were divided into four groups: diabetic control, diabetic treated with 500 mg/kg of metformin and diabetic treated with 250 or 500 mg/kg of ClEtOH for 21 days. The treatment of diabetic rats with 500 mg/kg of ClEtOH promoted an increase in the weight of liver, white adipose tissues and skeletal muscles, improving body weight gain. Diabetic rats treated with 500 mg/kg of ClEtOH also presented reduction in glycemia, glycosuria and urinary urea levels, and increase in liver glycogen content. HPLC chromatogram showed that quercetin is the major compound in the extract. The phosphorylation levels of adenosine monophosphate-activated protein kinase were increased in liver slices incubated in vitro with 50 µg/mL of ClEtOH, similarly to the incubation with metformin (50 µg/mL or quercetin (10 µg/mL. The antihyperglycemic effect of ClEtOH was similar to that of metformin and appears to be through inhibition of gluconeogenesis, since urinary urea was reduced and skeletal muscle mass was increased. These data indicate that the antidiabetic activity of the Combretum lanceolatum extract could be mediated, at least in part, through activation of adenosine monophosphateactivated protein kinase by quercetin.

  10. AMPK and Exercise: Glucose Uptake and Insulin Sensitivity

    Hayley M. O'Neill

    2013-02-01

    Full Text Available AMPK is an evolutionary conserved sensor of cellular energy status that is activated during exercise. Pharmacological activation of AMPK promotes glucose uptake, fatty acid oxidation, mitochondrial biogenesis, and insulin sensitivity; processes that are reduced in obesity and contribute to the development of insulin resistance. AMPK deficient mouse models have been used to provide direct genetic evidence either supporting or refuting a role for AMPK in regulating these processes. Exercise promotes glucose uptake by an insulin dependent mechanism involving AMPK. Exercise is important for improving insulin sensitivity; however, it is not known if AMPK is required for these improvements. Understanding how these metabolic processes are regulated is important for the development of new strategies that target obesity-induced insulin resistance. This review will discuss the involvement of AMPK in regulating skeletal muscle metabolism (glucose uptake, glycogen synthesis, and insulin sensitivity.

  11. CNX-012-570, a direct AMPK activator provides strong glycemic and lipid control along with significant reduction in body weight; studies from both diet-induced obese mice and db/db mice models

    Anil, Tharappel M; Harish, Chandrashekaran; Lakshmi, Mudigere N; Harsha, KrishnaReddy; Onkaramurthy, Mallappa; Sathish Kumar, Venkatesh; Shree, Nitya; Geetha, Venkatachalaiah; Balamurali, Gundalmandikal V; Gopala, Aralakuppe S; Madhusudhan Reddy, Bobbili; Govind, Madabosse K; Anup, Mammen O; Moolemath, Yoganand; Venkataranganna, Marikunte V.

    2014-01-01

    Objectives AMP activated protein kinase (AMPK) regulates the coordination of anabolic and catabolic processes and is an attractive therapeutic target for T2DM, obesity and metabolic syndrome. We report the anti-hyperglycemic and anti-hyperlipidemic effects of CNX-012-570 is an orally bioavailable small molecule (molecular weight of 530 Daltons) that directly activates AMPK in DIO and db/db animal models of diabetes. Methods Activity and efficacy of the compound was tested in cell based as wel...

  12. Curcumin attenuates glutamate neurotoxicity in the hippocampus by suppression of ER stress-associated TXNIP/NLRP3 inflammasome activation in a manner dependent on AMPK

    Li, Ying; Li, Jia; Li, Shanshan; Li, Yi; Wang, Xiangxiang; Liu, Baolin [Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, 639, Longmian Road, Nanjing 211198 (China); Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Research, China Pharmaceutical University, 639, Longmian Road, Nanjing 211198 (China); Fu, Qiang, E-mail: fuqiang@cpu.edu.cn [Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, 639, Longmian Road, Nanjing 211198 (China); Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Research, China Pharmaceutical University, 639, Longmian Road, Nanjing 211198 (China); Ma, Shiping, E-mail: spma@cpu.edu.cn [Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, 639, Longmian Road, Nanjing 211198 (China); Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Research, China Pharmaceutical University, 639, Longmian Road, Nanjing 211198 (China)

    2015-07-01

    Curcumin is a natural polyphenolic compound in Curcuma longa with beneficial effects on neuronal protection. This study aims to investigate the action of curcumin in the hippocampus subjected to glutamate neurotoxicity. Glutamate stimulation induced reactive oxygen species (ROS), endoplasmic reticulum stress (ER stress) and TXNIP/NLRP3 inflammasome activation, leading to damage in the hippocampus. Curcumin treatment in the hippocampus or SH-SY5Y cells inhibited IRE1α and PERK phosphorylation with suppression of intracellular ROS production. Curcumin increased AMPK activity and knockdown of AMPKα with specific siRNA abrogated its inhibitory effects on IRE1α and PERK phosphorylation, indicating that AMPK activity was essential for the suppression of ER stress. As a result, curcumin reduced TXNIP expression and inhibited NLRP3 inflammasome activation by downregulation of NLRP3 and cleaved caspase-1 induction, and thus reduced IL-1β secretion. Specific fluorescent probe and flow cytometry analysis showed that curcumin prevented mitochondrial malfunction and protected cell survival from glutamate neurotoxicity. Moreover, oral administration of curcumin reduced brain infarct volume and attenuated neuronal damage in rats subjected to middle cerebral artery occlusion. Immunohistochemistry showed that curcumin inhibited p-IRE1α, p-PERK and NLRP3 expression in hippocampus CA1 region. Together, these results showed that curcumin attenuated glutamate neurotoxicity by inhibiting ER stress-associated TXNIP/NLRP3 inflammasome activation via the regulation of AMPK, and thereby protected the hippocampus from ischemic insult. - Highlights: • Curcumin attenuates glutamate neurotoxicity in the hippocampus. • Curcumin suppresses ER stress in glutamate-induced hippocampus slices. • Curcumin inhibits TXNIP/NLRP3 inflammasome activation. • Regulation of AMPK by curcumin contributes to suppressing ER stress.

  13. Curcumin attenuates glutamate neurotoxicity in the hippocampus by suppression of ER stress-associated TXNIP/NLRP3 inflammasome activation in a manner dependent on AMPK

    Curcumin is a natural polyphenolic compound in Curcuma longa with beneficial effects on neuronal protection. This study aims to investigate the action of curcumin in the hippocampus subjected to glutamate neurotoxicity. Glutamate stimulation induced reactive oxygen species (ROS), endoplasmic reticulum stress (ER stress) and TXNIP/NLRP3 inflammasome activation, leading to damage in the hippocampus. Curcumin treatment in the hippocampus or SH-SY5Y cells inhibited IRE1α and PERK phosphorylation with suppression of intracellular ROS production. Curcumin increased AMPK activity and knockdown of AMPKα with specific siRNA abrogated its inhibitory effects on IRE1α and PERK phosphorylation, indicating that AMPK activity was essential for the suppression of ER stress. As a result, curcumin reduced TXNIP expression and inhibited NLRP3 inflammasome activation by downregulation of NLRP3 and cleaved caspase-1 induction, and thus reduced IL-1β secretion. Specific fluorescent probe and flow cytometry analysis showed that curcumin prevented mitochondrial malfunction and protected cell survival from glutamate neurotoxicity. Moreover, oral administration of curcumin reduced brain infarct volume and attenuated neuronal damage in rats subjected to middle cerebral artery occlusion. Immunohistochemistry showed that curcumin inhibited p-IRE1α, p-PERK and NLRP3 expression in hippocampus CA1 region. Together, these results showed that curcumin attenuated glutamate neurotoxicity by inhibiting ER stress-associated TXNIP/NLRP3 inflammasome activation via the regulation of AMPK, and thereby protected the hippocampus from ischemic insult. - Highlights: • Curcumin attenuates glutamate neurotoxicity in the hippocampus. • Curcumin suppresses ER stress in glutamate-induced hippocampus slices. • Curcumin inhibits TXNIP/NLRP3 inflammasome activation. • Regulation of AMPK by curcumin contributes to suppressing ER stress

  14. Advances in the Research of AMPK and its Subunit Genes

    R.S. Jiang

    2013-01-01

    Full Text Available AMP-activated kinase (AMPK is a heterotrimeric complex composed of three subunits and is the core energy sensor of the cell. The AMPK activity is important for survival during periods of stress and starvation and also has implications in type II diabetes, obesity, metabolic syndrome, longevity and cancer, etc. The activation of AMPK is triggered through binding of Adenosine Monophosphate Activated Proteins (AMP to the Bateman domains of the gamma subunit, leading to increased phosphorylation of the threonine 172 on the alpha subunit by inducing allosteric activation and inhibiting dephosphorylation. AMPK and its subunits have been the focuses of many researchers dealing with genetic and metabolic issues. The study makes a comprehensive review on the structure, function, distribution, enzyme activity, the genetic mutation and other aspects of AMPK and its subunit genes, with the aim to outline main aspects of present researches on AMPK and its subunits in animal genetics.

  15. Betulinic acid alleviates non-alcoholic fatty liver by inhibiting SREBP1 activity via the AMPK-mTOR-SREBP signaling pathway.

    Quan, Hai Yan; Kim, Do Yeon; Kim, Soo Jung; Jo, Hee Kyung; Kim, Go Woon; Chung, Sung Hyun

    2013-05-01

    Non-alcoholic fatty liver disease (NAFLD) is emerging as the most common liver disease in industrialized countries. The discovery of food components that can ameliorate NAFLD is therefore of interest. Betulinic acid (BA) is a triterpenoid with many pharmacological activities, but the effect of BA on fatty liver is as yet unknown. To explore the possible anti-fatty liver effects and their underlying mechanisms, we used insulin-resistant HepG2 cells, primary rat hepatocytes and liver tissue from ICR mice fed a high-fat diet (HFD). Oil Red O staining revealed that BA significantly suppressed excessive triglyceride accumulation in HepG2 cells and in the livers of mice fed a HFD. Ca(+2)-calmodulin dependent protein kinase kinase (CAMKK) and AMP-activated protein kinase (AMPK) were both activated by BA treatment. In contrast, the protein levels of sterol regulatory element-binding protein 1 (SREBP1), mammalian target of rapamycin (mTOR) and S6 kinase (S6K) were all reduced when hepatocytes were treated with BA for up to 24h. We found that BA activates AMPK via phosphorylation, suppresses SREBP1 mRNA expression, nuclear translocation and repressed SREBP1 target gene expression in HepG2 cells and primary hepatocytes, leading to reduced lipogenesis and lipid accumulation. These effects were completely abolished in the presence of STO-609 (a CAMKK inhibitor) or compound C (an AMPK inhibitor), indicating that the BA-induced reduction in hepatic steatosis was mediated via the CAMKK-AMPK-SREBP1 signaling pathway. Taken together, our results suggest that BA effectively ameliorates intracellular lipid accumulation in liver cells and thus is a potential therapeutic agent for the prevention of fatty liver disease. PMID:23435355

  16. Gain of function AMP-activated protein kinase γ3 mutation (AMPKγ3R200Q) in pig muscle increases glycogen storage regardless of AMPK activation.

    Scheffler, Tracy L; Park, Sungkwon; Roach, Peter J; Gerrard, David E

    2016-06-01

    Chronic activation of AMP-activated protein kinase (AMPK) increases glycogen content in skeletal muscle. Previously, we demonstrated that a mutation in the ryanodine receptor (RyR1(R615C)) blunts AMPK phosphorylation in longissimus muscle of pigs with a gain of function mutation in the AMPKγ3 subunit (AMPKγ3(R200Q)); this may decrease the glycogen storage capacity of AMPKγ3(R200Q) + RyR1(R615C) muscle. Therefore, our aim in this study was to utilize our pig model to understand how AMPKγ3(R200Q) and AMPK activation contribute to glycogen storage and metabolism in muscle. We selected and bred pigs in order to generate offspring with naturally occurring AMPKγ3(R200Q), RyR1(R615C), and AMPKγ3(R200Q) + RyR1(R615C) mutations, and also retained wild-type littermates (control). We assessed glycogen content and parameters of glycogen metabolism in longissimus muscle. Regardless of RyR1(R615C), AMPKγ3(R200Q) increased the glycogen content by approximately 70%. Activity of glycogen synthase (GS) without the allosteric activator glucose 6-phosphate (G6P) was decreased in AMPKγ3(R200Q) relative to all other genotypes, whereas both AMPKγ3(R200Q) and AMPKγ3(R200Q) + RyR1(R615C) muscle exhibited increased GS activity with G6P. Increased activity of GS with G6P was not associated with increased abundance of GS or hexokinase 2. However, AMPKγ3(R200Q) enhanced UDP-glucose pyrophosphorylase 2 (UGP2) expression approximately threefold. Although UGP2 is not generally considered a rate-limiting enzyme for glycogen synthesis, our model suggests that UGP2 plays an important role in increasing flux to glycogen synthase. Moreover, we have shown that the capacity for glycogen storage is more closely related to the AMPKγ3(R200Q) mutation than activity. PMID:27302990

  17. Hypothalamic AMPK as a Regulator of Energy Homeostasis

    Huynh, My Khanh Q.; Kinyua, Ann W.; Yang, Dong Joo

    2016-01-01

    Activated in energy depletion conditions, AMP-activated protein kinase (AMPK) acts as a cellular energy sensor and regulator in both central nervous system and peripheral organs. Hypothalamic AMPK restores energy balance by promoting feeding behavior to increase energy intake, increasing glucose production, and reducing thermogenesis to decrease energy output. Besides energy state, many hormones have been shown to act in concert with AMPK to mediate their anorexigenic and orexigenic central effects as well as thermogenic influences. Here we explore the factors that affect hypothalamic AMPK activity and give the underlying mechanisms for the role of central AMPK in energy homeostasis together with the physiological effects of hypothalamic AMPK on energy balance restoration. PMID:27547453

  18. Hypothalamic AMPK as a Regulator of Energy Homeostasis.

    Huynh, My Khanh Q; Kinyua, Ann W; Yang, Dong Joo; Kim, Ki Woo

    2016-01-01

    Activated in energy depletion conditions, AMP-activated protein kinase (AMPK) acts as a cellular energy sensor and regulator in both central nervous system and peripheral organs. Hypothalamic AMPK restores energy balance by promoting feeding behavior to increase energy intake, increasing glucose production, and reducing thermogenesis to decrease energy output. Besides energy state, many hormones have been shown to act in concert with AMPK to mediate their anorexigenic and orexigenic central effects as well as thermogenic influences. Here we explore the factors that affect hypothalamic AMPK activity and give the underlying mechanisms for the role of central AMPK in energy homeostasis together with the physiological effects of hypothalamic AMPK on energy balance restoration. PMID:27547453

  19. Histological evaluation of AMPK signalling in primary breast cancer

    AMP-activated protein kinase (AMPK) acts as a cellular fuel gauge that responds to energy stress by suppressing cell growth and biosynthetic processes, thus ensuring that energy-consuming processes proceed only if there are sufficient metabolic resources. Malfunction of the AMPK pathway may allow cancer cells to undergo uncontrolled proliferation irrespective of their molecular energy levels. The aim of this study was to examine the state of AMPK phosphorylation histologically in primary breast cancer in relation to clinical and pathological parameters. Immunohistochemistry was performed using antibodies to phospho-AMPK (pAMPK), phospho-Acetyl Co-A Carboxylase (pACC) an established target for AMPK, HER2, ERα, and Ki67 on Tissue Micro-Array (TMA) slides of two cohorts of 117 and 237 primary breast cancers. The quick score method was used for scoring and patterns of protein expression were compared with clinical and pathological data, including a minimum 5 years follow up. Reduced signal, compared with the strong expression in normal breast epithelium, using a pAMPK antibody was demonstrated in 101/113 (89.4%) and 217/236 (91.9%) of two cohorts of patients. pACC was significantly associated with pAMPK expression (p = 0.007 & p = 0.014 respectively). For both cohorts, reduced pAMPK signal was significantly associated with higher histological grade (p = 0.010 & p = 0.021 respectively) and axillary node metastasis (p = 0.061 & p = 0.039 respectively). No significant association was found between pAMPK and any of HER2, ERα, or Ki67 expression, disease-free survival or overall survival. This study extends in vitro evidence through immunohistochemistry to confirm that AMPK is dysfunctional in primary breast cancer. Reduced signalling via the AMPK pathway, and the inverse relationship with histological grade and axillary node metastasis, suggests that AMPK re-activation could have therapeutic potential in breast cancer

  20. : AMPK and skeletal muscle hypertrophy

    Mounier, Rémi; Lantier, Louise; Leclerc, Jocelyne; Sotiropoulos, Athanassia; Pende, Mario; Daegelen, Dominique; Sakamoto, Kei; Foretz, Marc; Viollet, Benoit

    2009-01-01

    10 pages; 6 figures; 49 références bibliographiques International audience Activation of AMP-activated protein kinase (AMPK) inhibits protein synthesis through the suppression of the mammalian target of rapamycin complex 1 (mTORC1), a critical regulator of muscle growth. The purpose of this investigation was to determine the role of the AMPKalpha1 catalytic subunit on muscle cell size control and adaptation to muscle hypertrophy. We found that AMPKalpha1(-/-) primary cultured myotubes a...

  1. Combined Treatment of MCF-7 Cells with AICAR and Methotrexate, Arrests Cell Cycle and Reverses Warburg Metabolism through AMP-Activated Protein Kinase (AMPK and FOXO1.

    Tamás Fodor

    Full Text Available Cancer cells are characterized by metabolic alterations, namely, depressed mitochondrial oxidation, enhanced glycolysis and pentose phosphate shunt flux to support rapid cell growth, which is called the Warburg effect. In our study we assessed the metabolic consequences of a joint treatment of MCF-7 breast cancer cells with AICAR, an inducer of AMP-activated kinase (AMPK jointly with methotrexate (MTX, a folate-analog antimetabolite that blunts de novo nucleotide synthesis. MCF7 cells, a model of breast cancer cells, were resistant to the individual application of AICAR or MTX, however combined treatment of AICAR and MTX reduced cell proliferation. Prolonged joint application of AICAR and MTX induced AMPK and consequently enhanced mitochondrial oxidation and reduced the rate of glycolysis. These metabolic changes suggest an anti-Warburg rearrangement of metabolism that led to the block of the G1/S and the G2/M transition slowing down cell cycle. The slowdown of cell proliferation was abolished when mitotropic transcription factors, PGC-1α, PGC-1β or FOXO1 were silenced. In human breast cancers higher expression of AMPKα and FOXO1 extended survival. AICAR and MTX exerts similar additive antiproliferative effect on other breast cancer cell lines, such as SKBR and 4T1 cells, too. Our data not only underline the importance of Warburg metabolism in breast cancer cells but nominate the AICAR+MTX combination as a potential cytostatic regime blunting Warburg metabolism. Furthermore, we suggest the targeting of AMPK and FOXO1 to combat breast cancer.

  2. Combined Treatment of MCF-7 Cells with AICAR and Methotrexate, Arrests Cell Cycle and Reverses Warburg Metabolism through AMP-Activated Protein Kinase (AMPK) and FOXO1.

    Fodor, Tamás; Szántó, Magdolna; Abdul-Rahman, Omar; Nagy, Lilla; Dér, Ádám; Kiss, Borbála; Bai, Peter

    2016-01-01

    Cancer cells are characterized by metabolic alterations, namely, depressed mitochondrial oxidation, enhanced glycolysis and pentose phosphate shunt flux to support rapid cell growth, which is called the Warburg effect. In our study we assessed the metabolic consequences of a joint treatment of MCF-7 breast cancer cells with AICAR, an inducer of AMP-activated kinase (AMPK) jointly with methotrexate (MTX), a folate-analog antimetabolite that blunts de novo nucleotide synthesis. MCF7 cells, a model of breast cancer cells, were resistant to the individual application of AICAR or MTX, however combined treatment of AICAR and MTX reduced cell proliferation. Prolonged joint application of AICAR and MTX induced AMPK and consequently enhanced mitochondrial oxidation and reduced the rate of glycolysis. These metabolic changes suggest an anti-Warburg rearrangement of metabolism that led to the block of the G1/S and the G2/M transition slowing down cell cycle. The slowdown of cell proliferation was abolished when mitotropic transcription factors, PGC-1α, PGC-1β or FOXO1 were silenced. In human breast cancers higher expression of AMPKα and FOXO1 extended survival. AICAR and MTX exerts similar additive antiproliferative effect on other breast cancer cell lines, such as SKBR and 4T1 cells, too. Our data not only underline the importance of Warburg metabolism in breast cancer cells but nominate the AICAR+MTX combination as a potential cytostatic regime blunting Warburg metabolism. Furthermore, we suggest the targeting of AMPK and FOXO1 to combat breast cancer. PMID:26919657

  3. Regulation and function of AMPK in physiology and diseases

    Jeon, Sang-Min

    2016-01-01

    5′-adenosine monophosphate (AMP)-activated protein kinase (AMPK) is an evolutionarily conserved serine/threonine kinase that was originally identified as the key player in maintaining cellular energy homeostasis. Intensive research over the last decade has identified diverse molecular mechanisms and physiological conditions that regulate the AMPK activity. AMPK regulates diverse metabolic and physiological processes and is dysregulated in major chronic diseases, such as obesity, inflammation, diabetes and cancer. On the basis of its critical roles in physiology and pathology, AMPK is emerging as one of the most promising targets for both the prevention and treatment of these diseases. In this review, we discuss the current understanding of the molecular and physiological regulation of AMPK and its metabolic and physiological functions. In addition, we discuss the mechanisms underlying the versatile roles of AMPK in diabetes and cancer. PMID:27416781

  4. Compartmentalized AMPK Signaling Illuminated by Genetically Encoded Molecular Sensors and Actuators

    Takafumi Miyamoto

    2015-04-01

    Full Text Available AMP-activated protein kinase (AMPK, whose activity is a critical determinant of cell health, serves a fundamental role in integrating extracellular and intracellular nutrient information into signals that regulate various metabolic processes. Despite the importance of AMPK, its specific roles within the different intracellular spaces remain unresolved, largely due to the lack of real-time, organelle-specific AMPK activity probes. Here, we present a series of molecular tools that allows for the measurement of AMPK activity at the different subcellular localizations and that allows for the rapid induction of AMPK inhibition. We discovered that AMPKα1, not AMPKα2, was the subunit that preferentially conferred spatial specificity to AMPK, and that inhibition of AMPK activity at the mitochondria was sufficient for triggering cytosolic ATP increase. These findings suggest that genetically encoded molecular probes represent a powerful approach for revealing the basic principles of the spatiotemporal nature of AMPK regulation.

  5. Glucose-induced repression of PPARalpha gene expression in pancreatic beta-cells involves PP2A activation and AMPK inactivation

    Ravnskjaer, Kim; Boergesen, Michael; Dalgaard, Louise T;

    2006-01-01

    mechanism underlying this transcriptional repression by glucose remains unclear. Here we report that glucose-induced repression of PPARalpha gene expression in INS-1E cells is independent of beta-cell excitation and insulin secretion but requires activation of protein phosphatase 2A in a process involving...... AMPKalpha1 using RNAi suppressed PPARalpha expression, thereby mimicking the effect of glucose. These results indicate that activation of protein phosphatase 2A and subsequent inactivation of AMPK is necessary for glucose repression of PPARalpha expression in pancreatic beta-cells....

  6. Oocyte activation and latent HIV-1 reactivation: AMPK as a common mechanism of action linking the beginnings of life and the potential eradication of HIV-1.

    Finley, Jahahreeh

    2016-08-01

    In all mammalian species studied to date, the initiation of oocyte activation is orchestrated through alterations in intracellular calcium (Ca(2+)) signaling. Upon sperm binding to the oocyte plasma membrane, a sperm-associated phospholipase C (PLC) isoform, PLC zeta (PLCζ), is released into the oocyte cytoplasm. PLCζ hydrolyzes phosphatidylinositol 4,5-bisphosphate (PIP2) to produce diacylglycerol (DAG), which activates protein kinase C (PKC), and inositol 1,4,5-trisphosphate (IP3), which induces the release of Ca(2+) from endoplasmic reticulum (ER) Ca(2+) stores. Subsequent Ca(2+) oscillations are generated that drive oocyte activation to completion. Ca(2+) ionophores such as ionomycin have been successfully used to induce artificial human oocyte activation, facilitating fertilization during intra-cytoplasmic sperm injection (ICSI) procedures. Early studies have also demonstrated that the PKC activator phorbol 12-myristate 13-acetate (PMA) acts synergistically with Ca(2+) ionophores to induce parthenogenetic activation of mouse oocytes. Interestingly, the Ca(2+)-induced signaling cascade characterizing sperm or chemically-induced oocyte activation, i.e. the "shock and live" approach, bears a striking resemblance to the reactivation of latently infected HIV-1 viral reservoirs via the so called "shock and kill" approach, a method currently being pursued to eradicate HIV-1 from infected individuals. PMA and ionomycin combined, used as positive controls in HIV-1 latency reversal studies, have been shown to be extremely efficient in reactivating latent HIV-1 in CD4(+) memory T cells by inducing T cell activation. Similar to oocyte activation, T cell activation by PMA and ionomycin induces an increase in intracellular Ca(2+) concentrations and activation of DAG, PKC, and downstream Ca(2+)-dependent signaling pathways necessary for proviral transcription. Interestingly, AMPK, a master regulator of cell metabolism that is activated thorough the induction of cellular

  7. AMPK in the Brain: Its Roles in Energy Balance and Neuroprotection

    Ronnett, Gabriele V.; Ramamurthy, Santosh; Kleman, Amy M.; Landree, Leslie E.; Aja, Susan

    2009-01-01

    Adenosine monophosphate-activated protein kinase (AMPK) senses metabolic stress and integrates diverse physiological signals to restore energy balance. Multiple functions are indicated for AMPK in the CNS. While all neurons sense their own energy status, some integrate neuro-humoral signals to assess organismal energy balance. A variety of disease states may involve AMPK, so determining the underlying mechanisms is important. We review the impact of altered AMPK activity under physiological (...

  8. Role of AMPK in skeletal muscle metabolic regulation and adaptation in relation to exercise

    Jørgensen, Sebastian Beck; Richter, Erik; Wojtaszewski, Jørgen

    2006-01-01

    The 5'-AMP-activated protein kinase (AMPK) is a potent regulator of skeletal muscle metabolism and gene expression. AMPK is activated both in response to in vivo exercise and ex vivo contraction. AMPK is therefore believed to be an important signalling molecule in regulating muscle metabolism...... furthermore discuss the possible role of AMPK as a master switch in skeletal muscle metabolism with the main focus on AMPK in metabolic regulation during muscle work. Finally, AMPK has a well established role in regulating expression of genes encoding various enzymes in muscle, and this issue is discussed in...... during exercise as well as in adaptation of skeletal muscle to exercise training. The first part of this review is focused on different mechanisms regulating AMPK activity during muscle work such as alterations in nucleotide concentrations, availability of energy substrates and upstream AMPK kinases. We...

  9. Cafeteria diet-induced insulin resistance is not associated with decreased insulin signaling or AMPK activity and is alleviated by physical training in rats

    Brandt, Nina; De Bock, Katrien; Richter, Erik A.; Hespel, Peter

    2010-01-01

    Brandt N, De Bock K, Richter EA, Hespel P. Cafeteria diet-induced insulin resistance is not associated with decreased insulin signaling or AMPK activity and is alleviated by physical training in rats. Am J Physiol Endocrinol Metab 299: E215-E224, 2010. First published May 18, 2010; doi:10.1152/ajpendo.00098.2010.-Excess energy intake via a palatable low-fat diet (cafeteria diet) is known to induce obesity and glucose intolerance in rats. However, the molecular mechanisms behind this adaptatio...

  10. The proteasome inhibitor bortezomib induces testicular toxicity by upregulation of oxidative stress, AMP-activated protein kinase (AMPK) activation and deregulation of germ cell development in adult murine testis

    Understanding how chemotherapeutic agents mediate testicular toxicity is crucial in light of compelling evidence that male infertility, one of the severe late side effects of intensive cancer treatment, occurs more often than they are expected to. Previous study demonstrated that bortezomib (BTZ), a 26S proteasome inhibitor used to treat refractory multiple myeloma (MM), exerts deleterious impacts on spermatogenesis in pubertal mice via unknown mechanisms. Here, we showed that intermittent treatment with BTZ resulted in fertility impairment in adult mice, evidenced by testicular atrophy, desquamation of immature germ cells and reduced caudal sperm storage. These deleterious effects may originate from the elevated apoptosis in distinct germ cells during the acute phase and the subsequent disruption of Sertoli–germ cell anchoring junctions (AJs) during the late recovery. Mechanistically, balance between AMP-activated protein kinase (AMPK) activation and Akt/ERK pathway appeared to be indispensable for AJ integrity during the late testicular recovery. Of particular interest, the upregulated testicular apoptosis and the following disturbance of Sertoli–germ cell interaction may both stem from the excessive oxidative stress elicited by BTZ exposure. We also provided the in vitro evidence that AMPK-dependent mechanisms counteract follicle-stimulating hormone (FSH) proliferative effects in BTZ-exposed Sertoli cells. Collectively, BTZ appeared to efficiently prevent germ cells from normal development via multiple mechanisms in adult mice. Employment of antioxidants and/or AMPK inhibitor may represent an attractive strategy of fertility preservation in male MM patients exposed to conventional BTZ therapy and warrants further investigation. - Highlights: • Intermittent treatment with BTZ caused fertility impairment in adult mice. • BTZ treatment elicited apoptosis during early phase of testicular recovery. • Up-regulation of oxidative stress by BTZ treatment

  11. The proteasome inhibitor bortezomib induces testicular toxicity by upregulation of oxidative stress, AMP-activated protein kinase (AMPK) activation and deregulation of germ cell development in adult murine testis

    Li, Wei [Department of Human Anatomy, Histology and Embryology, Fourth Military Medical University, Xi' an 710032 (China); Fu, Jianfang [Department of Endocrinology, Xijing Hospital, Fourth Military Medical University, Xi' an 710032 (China); Zhang, Shun [Reproductive Medicine Center, Department of Gynecology and Obstetrics, Tangdu Hospital, Fourth Military Medical University, Xi' an 710038 (China); Zhao, Jie [Department of Human Anatomy, Histology and Embryology, Fourth Military Medical University, Xi' an 710032 (China); Xie, Nianlin, E-mail: xienianlin@126.com [Department of Thoracic Surgery, Tangdu Hospital, Fourth Military Medical University, Xi' an 710038 (China); Cai, Guoqing, E-mail: firstchair@fmmu.edu.cn [Department of Gynaecology and Obstetrics, Xijing Hospital, Fourth Military Medical University, Xi' an 710032 (China)

    2015-06-01

    Understanding how chemotherapeutic agents mediate testicular toxicity is crucial in light of compelling evidence that male infertility, one of the severe late side effects of intensive cancer treatment, occurs more often than they are expected to. Previous study demonstrated that bortezomib (BTZ), a 26S proteasome inhibitor used to treat refractory multiple myeloma (MM), exerts deleterious impacts on spermatogenesis in pubertal mice via unknown mechanisms. Here, we showed that intermittent treatment with BTZ resulted in fertility impairment in adult mice, evidenced by testicular atrophy, desquamation of immature germ cells and reduced caudal sperm storage. These deleterious effects may originate from the elevated apoptosis in distinct germ cells during the acute phase and the subsequent disruption of Sertoli–germ cell anchoring junctions (AJs) during the late recovery. Mechanistically, balance between AMP-activated protein kinase (AMPK) activation and Akt/ERK pathway appeared to be indispensable for AJ integrity during the late testicular recovery. Of particular interest, the upregulated testicular apoptosis and the following disturbance of Sertoli–germ cell interaction may both stem from the excessive oxidative stress elicited by BTZ exposure. We also provided the in vitro evidence that AMPK-dependent mechanisms counteract follicle-stimulating hormone (FSH) proliferative effects in BTZ-exposed Sertoli cells. Collectively, BTZ appeared to efficiently prevent germ cells from normal development via multiple mechanisms in adult mice. Employment of antioxidants and/or AMPK inhibitor may represent an attractive strategy of fertility preservation in male MM patients exposed to conventional BTZ therapy and warrants further investigation. - Highlights: • Intermittent treatment with BTZ caused fertility impairment in adult mice. • BTZ treatment elicited apoptosis during early phase of testicular recovery. • Up-regulation of oxidative stress by BTZ treatment

  12. AMPK controls exercise endurance, mitochondrial oxidative capacity, and skeletal muscle integrity. : AMPK in skeletal musclemetabolic adaptation

    Lantier, Louise; Fentz, Joachim; Mounier, Rémi; Leclerc, Jocelyne; Treebak, Jonas,; Pehmøller, Christian; Sanz, Nieves; Sakakibara, Iori; Saint-Amand, Emmanuelle; Rimbaud, Stéphanie; Maire, Pascal; Marette, André; Ventura-Clapier, Renée; Ferry, Arnaud; Wojtaszewski, Jørgen,

    2014-01-01

    : AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that plays a central role in skeletal muscle metabolism. We used skeletal muscle-specific AMPKα1α2 double-knockout (mdKO) mice to provide direct genetic evidence of the physiological importance of AMPK in regulating muscle exercise capacity, mitochondrial function, and contraction-stimulated glucose uptake. Exercise performance was significantly reduced in the mdKO mice, with a reduction in maximal force production an...

  13. Immunometabolism of AMPK in insulin resistance and atherosclerosis.

    Fullerton, Morgan D; Steinberg, Gregory R; Schertzer, Jonathan D

    2013-02-25

    Obesity leads to insulin resistance and atherosclerosis, which precede Type 2 diabetes and cardiovascular disease. Immunometabolism addresses how metabolic and inflammatory pathways converge to maintain health and a contemporary problem is determining how obesity-induced inflammation precipitates chronic diseases such as insulin resistance and atherosclerosis. AMP-activated protein kinase (AMPK) is an important serine/threonine kinase well known for regulating metabolic processes and maintaining energy homeostasis. However, both metabolic and immunological AMPK-mediated effects play a role in disease. Pro-inflammatory mediators suppress AMPK activity and hinder lipid oxidation. In addition, AMPK activation curbs inflammation by directly inhibiting pro-inflammatory signaling pathways and limiting the build-up of specific lipid intermediates that elicit immune responses. In the context of obesity and chronic disease, these reciprocal responses involve both immune and metabolic cells. Therefore, the immunometabolism of AMPK-mediated processes and therapeutics should be considered in atherosclerosis and insulin resistance. PMID:22361321

  14. 1,4-Dihydropyridines Active on the SIRT1/AMPK Pathway Ameliorate Skin Repair and Mitochondrial Function and Exhibit Inhibition of Proliferation in Cancer Cells.

    Valente, Sergio; Mellini, Paolo; Spallotta, Francesco; Carafa, Vincenzo; Nebbioso, Angela; Polletta, Lucia; Carnevale, Ilaria; Saladini, Serena; Trisciuoglio, Daniela; Gabellini, Chiara; Tardugno, Maria; Zwergel, Clemens; Cencioni, Chiara; Atlante, Sandra; Moniot, Sébastien; Steegborn, Clemens; Budriesi, Roberta; Tafani, Marco; Del Bufalo, Donatella; Altucci, Lucia; Gaetano, Carlo; Mai, Antonello

    2016-02-25

    Modulators of sirtuins are considered promising therapeutic targets for the treatment of cancer, cardiovascular, metabolic, inflammatory, and neurodegenerative diseases. Here we prepared new 1,4-dihydropyridines (DHPs) bearing changes at the C2/C6, C3/C5, C4, or N1 position. Tested with the SIRTainty procedure, some of them displayed increased SIRT1 activation with respect to the prototype 3a, high NO release in HaCat cells, and ameliorated skin repair in a mouse model of wound healing. In C2C12 myoblasts, two of them improved mitochondrial density and functions. All the effects were reverted by coadministration of compound C (9), an AMPK inhibitor, or of EX-527 (10), a SIRT1 inhibitor, highlighting the involvement of the SIRT1/AMPK pathway in the action of DHPs. Finally, tested in a panel of cancer cells, the water-soluble form of 3a, compound 8, displayed antiproliferative effects in the range of 8-35 μM and increased H4K16 deacetylation, suggesting a possible role for SIRT1 activators in cancer therapy. PMID:26689352

  15. Rosemary (Rosmarinus officinalis L.) extract regulates glucose and lipid metabolism by activating AMPK and PPAR pathways in HepG2 cells.

    Tu, Zheng; Moss-Pierce, Tijuana; Ford, Paul; Jiang, T Alan

    2013-03-20

    An epidemic of metabolic disorders such as obesity and diabetes is rising dramatically. Using natural products as potential preventive and therapeutic interventions for these disorders has drawn worldwide attention. Rosemary has been shown to lower blood glucose and cholesterol levels and mitigate weight gain in several in vivo studies. However, the mechanisms are essentially unknown. We investigated the effects of rosemary extract on metabolism and demonstrated that rosemary extract significantly increased glucose consumption in HepG2 cells. The phosphorylation of AMP-activated protein kinase (AMPK) and its substrate, acetyl-CoA carboxylase (ACC), was increased by rosemary extract. Rosemary extract also transcriptionally regulated the genes involved in metabolism, including SIRT1, PPARγ coactivator 1α (PGC1α), glucose-6-phosphatase (G6Pase), ACC, and low-density lipoprotein receptor (LDLR). Furthermore, the PPARγ-specific antagonist GW9662 diminished rosemary's effects on glucose consumption. Overall, our study suggested that rosemary potentially increases liver glycolysis and fatty acid oxidation by activating AMPK and PPAR pathways. PMID:23432097

  16. Monascin and ankaflavin act as natural AMPK activators with PPARα agonist activity to down-regulate nonalcoholic steatohepatitis in high-fat diet-fed C57BL/6 mice.

    Hsu, Wei-Hsuan; Chen, Ting-Hung; Lee, Bao-Hong; Hsu, Ya-Wen; Pan, Tzu-Ming

    2014-02-01

    Yellow pigments monascin (MS) and ankaflavin (AK) are secondary metabolites derived from Monascus-fermented products. The hypolipidemic and anti-inflammatory effects of MS and AK indicate that they have potential on preventing or curing nonalcoholic fatty liver disease (NAFLD). Oleic acid (OA) and high-fat diet were used to induce steatosis in FL83B hepatocytes and NAFLD in mice, respectively. We found that both MS and AK prevented fatty acid accumulation in hepatocytes by inhibiting fatty acid uptake, lipogenesis, and promoting fatty acid beta-oxidation mediated by activating peroxisome proliferator-activated receptor (PPAR)-α and AMP-activated kinase (AMPK). Furthermore, MS and AK significantly attenuated high-fat diet-induced elevation of total cholesterol (TC), triaceylglycerol (TG), free fatty acid (FFA), and low density lipoprotein-cholesterol (LDL-C) in plasma. MS and AK promoted AMPK phosphorylation, suppressed the steatosis-related mRNA expression and inflammatory cytokines secretion, as well as upregulated farnesoid X receptor (FXR), peroxisome proliferator-activated receptor gamma co-activator (PGC)-1α, and PPARα expression to induce fatty acid oxidation in the liver of mice. We provided evidence that MS and AK act as PPARα agonists to upregulate AMPK activity and attenuate NAFLD. MS and AK may be supplied in food supplements or developed as functional foods to reduce the risk of diabetes and obesity. PMID:24275089

  17. Role of AMPK in Regulating Muscle Insulin Sensitivity

    Kjøbsted, Rasmus

    skeletal muscle in response to exercise and contraction. It is considered an important sensor of cellular energy-fuel status and fulfills the purpose of regulating energy-fuel homeostasis. Based on this, the aim of the present PhD was to investigate the involvement of AMPK in regulating insulin sensitivity....... Results obtained during this PhD support a role of AMPK in regulating muscle insulin sensitivity, which may occur through phosphorylation of the downstream target TBC1D4. We find that prior AICAR treatment (pharmacological AMPK activator) and in situ contraction enhance mouse muscle insulin sensitivity in...... an AMPK-dependent manner. This is associated with and positively correlated to an increased phosphorylation of TBC1D4 Thr642 and Ser704, of which Thr642 previously has been shown to be important for insulin-stimulated glucose uptake in skeletal muscle. Furthermore, we find intact regulation of AMPK...

  18. Docosahexaenoic Acid Induces Cell Death in Human Non-Small Cell Lung Cancer Cells by Repressing mTOR via AMPK Activation and PI3K/Akt Inhibition

    Nayeong Kim

    2015-01-01

    Full Text Available The anticancer properties and mechanism of action of omega-3 polyunsaturated fatty acids (ω3-PUFAs have been demonstrated in several cancers; however, the mechanism in lung cancer remains unclear. Here, we show that docosahexaenoic acid (DHA, a ω3-PUFA, induced apoptosis and autophagy in non-small cell lung cancer (NSCLC cells. DHA-induced cell death was accompanied by AMP-activated protein kinase (AMPK activation and inactivated phosphatidylinositol 3-kinase (PI3K/Akt/mammalian target of rapamycin (mTOR signaling. Knocking down AMPK and overexpressing Akt increased mTOR activity and attenuated DHA-induced cell death, suggesting that DHA induces cell death via AMPK- and Akt-regulated mTOR inactivation. This was confirmed in Fat-1 transgenic mice, which produce ω3-PUFAs. Lewis lung cancer (LLC tumor cells implanted into Fat-1 mice showed slower growth, lower phospho-Akt levels, and higher levels of apoptosis and autophagy than cells implanted into wild-type mice. Taken together, these data suggest that DHA-induced apoptosis and autophagy in NSCLC cells are associated with AMPK activation and PI3K/Akt inhibition, which in turn lead to suppression of mTOR; thus ω3-PUFAs may be utilized as potential therapeutic agents for NSCLC treatment.

  19. 脂肪细胞AMPK活性对NF-κB活性的影响%Effects of the Phosphorylation of AMPK on NF-κB Activity in Adipocytes

    郑丽英; 张君; 徐文静; 陆环; 李宏; 冯晓朋; 王金宝; 谢建新

    2012-01-01

    为检测AICAR激活及Compound C抑制脂肪细胞AMPK磷酸化后对NF-κB的磷酸化活性的影响,探讨肥胖启动炎症的分子机制.将3T3-L1细胞诱导为成熟脂肪细胞后,实验分3个处理:基础培养液组(对照组)、实验组(基础培养液组分别加入AICAR和Compound C).运用Western blot检测药物干预后AMPK与NF-κB的磷酸化水平.结果显示,AICAR培养1h脂肪细胞内AMPK磷酸化水平增加,Compound C培养1h脂肪细胞内AMPK磷酸化水平降低,差异有统计学意义(P<0.05).AICAR培养1h脂肪细胞内NF-κB磷酸化水平降低,Compound C培养1h脂肪细胞NF-κB磷酸化水平增高,差异有统计学意义(P<0.05).由此可知,AMPK活性与NF-κB活性呈一定的负相关,AMPK可抑制NF-κB信号,肥胖导致炎症可能是AMPK活性降低引发NF-κB信号活性增强有关.%To explore the effects of the phosphorylation of AMPK activated by AICAR and inhibited by Compound C on NF-κB activity in adipocytes, and investigate molecular mechanisms of obesity-related inflammation. 3T3-L1 cells were induced into adipocytes, and three treatments were used in this experiment. AICAR and Compound C were added respectively into the standard culture medium (control), AMPK and NF-kB phosphorylation were examined by Western blot. AICAR activated AMPK and inhibited NF-κB phospho-rylation(P<0.05). Compound C inhibited AMPK and activated NF-κB phosphorylatioa AMPK activities and NF-κB activities have a certain negative correlation, and AMPK can inhibit NF-κB signaling pathway. The decrease of AMPK activities may enhance the activities of NF-kB signaling pathway, and then lead to obesity-related inflammation.

  20. Quercetin inhibits AMPK/TXNIP activation and reduces inflammatory lesions to improve insulin signaling defect in the hypothalamus of high fructose-fed rats.

    Zhang, Qing-Yu; Pan, Ying; Wang, Rong; Kang, Lin-Lin; Xue, Qiao-Chu; Wang, Xiao-Ning; Kong, Ling-Dong

    2014-04-01

    Fructose is a nutritional composition of fruits and honey. Its excess consumption induces insulin resistance-associated metabolic diseases. Hypothalamic insulin signaling plays a pivotal role in controlling whole-body insulin sensitivity and energy homeostasis. Quercetin, a natural flavonoid, has been reported to ameliorate high fructose-induced rat insulin resistance and hyperlipidemia. In this study, we investigated its regulatory effects on the hypothalamus of high fructose-fed rats. Rats were fed 10% fructose in drinking water for 10 weeks. After 4 weeks, these animals were orally treated with quercetin (50 and 100 mg/kg), allopurinol (5 mg/kg) and water daily for the next 6 weeks, respectively. Quercetin effectively restored high fructose-induced hypothalamic insulin signaling defect by up-regulating the phosphorylation of insulin receptor and protein kinase B. Furthermore, quercetin was found to reduce metabolic nutrient sensors adenosine monophosphate-activated protein kinase (AMPK) activation and thioredoxin-interacting protein (TXNIP) overexpression, as well as the glutamine-glutamate cycle dysfunction in the hypothalamus of high fructose-fed rats. Subsequently, it ameliorated high fructose-caused hypothalamic inflammatory lesions in rats by suppressing the activation of hypothalamic nuclear factor κB (NF-κB) pathway and NOD-like receptor 3 (NLRP3) inflammasome with interleukin 1β maturation. Allopurinol had similar effects. These results provide in vivo evidence that quercetin-mediated down-regulation of AMPK/TXNIP and subsequent inhibition of NF-κB pathway/NLRP3 inflammasome activation in the hypothalamus of rats may be associated with the reduction of hypothalamic inflammatory lesions, contributing to the improvement of hypothalamic insulin signaling defect in this model. Thus, quercetin with the central activity may be a therapeutic for high fructose-induced insulin resistance and hyperlipidemia in humans. PMID:24491314

  1. The In Vivo Antidiabetic Activity of Nigella sativa Is Mediated through Activation of the AMPK Pathway and Increased Muscle Glut4 Content

    Ali Benhaddou-Andaloussi

    2011-01-01

    Full Text Available The antidiabetic effect of N. sativa seed ethanol extract (NSE was assessed in Meriones shawi after development of diabetes. Meriones shawi were divided randomly into four groups: normal control, diabetic control, diabetic treated with NSE (2 g eq plant/kg or with metformin (300 mg/kg positive control, both administered by daily intragastric gavage for 4 weeks. Glycaemia and body weight were evaluated weekly. At study's end, an Oral Glucose Tolerance Test (OGTT was performed to estimate insulin sensitivity. Upon sacrifice, plasma lipid profile, insulin, leptin, and adiponectin levels were assessed. ACC phosphorylation and Glut4 protein content were determined in liver and skeletal muscle. NSE animals showed a progressive normalization of glycaemia, albeit slower than that of metformin controls. Moreover, NSE increased insulinemia and HDL-cholesterol, compared to diabetic controls. Leptin and adiponectin were unchanged. NSE treatment decreased OGTT and tended to decrease liver and muscle triglyceride content. NSE stimulated muscle and liver ACC phosphorylation and increased muscle Glut4. These results confirm NSE's previously reported hypoglycaemic and hypolipidemic activity. More significantly, our data demonstrate that in vivo treatment with NSE exerts an insulin-sensitizing action by enhancing ACC phosphorylation, a major component of the insulin-independent AMPK signaling pathway, and by enhancing muscle Glut4 expression.

  2. Baicalein induces autophagic cell death through AMPK/ULK1 activation and downregulation of mTORC1 complex components in human cancer cells.

    Aryal, Pramod; Kim, Kijoong; Park, Pil-Hoon; Ham, Seongho; Cho, Junghee; Song, Kyung

    2014-10-01

    Baicalein, a flavonoid and aglycon hydrolyzed from baicalin, has anticancer properties in several human carcinomas, but its molecular mechanisms of action remain unclear. Here, we show that baicalein leads to human cancer cell death by inducing autophagy rather than apoptosis, because cell death induced by baicalein was completely reversed by suppressing the expression levels of key molecules in autophagy such as Beclin 1, vacuolar protein sorting 34 (Vps34), autophagy-related (Atg)5 and Atg7, but not by pan-caspase inhibitor. Our data revealed that baicalein significantly increased the number of green fluorescence protein-cytosol-associated protein light chain 3 (GFP-LC3)-containing puncta and LC3B-II expression levels, which were further enhanced by chloroquine treatment. Furthermore, a luciferase-based reporter assay showed that the ratio of RLuc-LC3wt/RLuc-LC3G120A was greatly reduced. The data suggested that baicalein induced not only autophagosome formation, but also autophagic flux. Experiments using short interfering RNAs and pharmacological inhibitors revealed that Beclin 1, Vps34, Atg5, Atg7 and UNC-51 (Caenorhabditis elegans)-like kinase 1 (ULK1) play pivotal roles in mediating baicalein-induced autophagy. Moreover, baicalein activated AMP-activated protein kinase (AMPK)α, leading to ULK1 activation through phosphorylation at Ser555, whereas both protein and mRNA levels of mammalian target of rapamycin (mTOR) and Raptor, upstream inhibitors of ULK1 and autophagy, were markedly downregulated by baicalein. Our data suggest that the anticancer effects of baicalein are mainly due to autophagic cell death through activation of the AMPK/ULK1 pathway and inhibition of mTOR/Raptor complex 1 expression. These results provide new mechanistic insights into the anticancer functions of autophagy inducers, such as baicalein, which may be used as potential therapeutics for cancer treatment. PMID:25132405

  3. Exercício físico reduz a hiperglicemia de jejum em camundongos diabéticos através da ativação da AMPK Physical exercise decreases fasting hyperglycemia in diabetic mice through AMPK activation

    Mônica F. de Pádua

    2009-06-01

    condition, the insulin tolerance test (ITT and Western blot technique, were combined to assess the glucose homeostasis in diabetic mice (ob/ob and db/db after a single swimming session. RESULTS: Fasting hyperglycemia, severe insulin resistance and deficiency in the AMPK/ACC signaling in muscle and liver observed in the diabetic mice were reversed after the exercise session. The restoration of AMPK/ACC signaling reduced the expression of the gluconeogenic enzyme, PEPCK in the liver, and increased the translocation of GLUT4 in the skeletal muscle. These data indicate that the activation of AMPK/ACC pathway induced by physical exercise is important to reduce fasting glucose levels in experimental models of type 2 diabetes. These data open new insights for determination of physical activity control on the glucose homeostasis in diabetic patients.

  4. Estradiol Regulates Brown Adipose Tissue Thermogenesis via Hypothalamic AMPK

    Martínez de Morentin, Pablo B.; González-García, Ismael; Martins, Luís; Lage, Ricardo; Fernández-Mallo, Diana; Martínez-Sánchez, Noelia; Ruíz-Pino, Francisco; Liu, Ji; Morgan, Donald A.; Pinilla, Leonor; Gallego, Rosalía; Saha, Asish K.; Kalsbeek, Andries; Fliers, Eric; Bisschop, Peter H.

    2014-01-01

    Summary Estrogens play a major role in the modulation of energy balance through central and peripheral actions. Here, we demonstrate that central action of estradiol (E2) inhibits AMP-activated protein kinase (AMPK) through estrogen receptor alpha (ERα) selectively in the ventromedial nucleus of the hypothalamus (VMH), leading to activation of thermogenesis in brown adipose tissue (BAT) through the sympathetic nervous system (SNS) in a feeding-independent manner. Genetic activation of AMPK in...

  5. AMPK : a master energy regulator for gonadal functions.

    Michael eBertoldo

    2015-07-01

    Full Text Available From c.elegans to mammals (including humans, nutrition and energy metabolism strongly influence reproduction. At the cellular level, some detectors of energy status indicate whether energy reserves are abundant (obesity, or poor (diet restriction. One of these detectors is AMPK (5 'AMP-activated protein kinase, a protein kinase activated by ATP deficiency but also by several natural substances such as polyphenols or synthetic molecules like metformin, used in the treatment of insulin resistance. AMPK is expressed in muscle and liver, but also in the ovary and testis. This review focuses on the main effects of AMPK identified in gonadal cells. We describe the role of AMPK in gonadal steroidogenesis, in proliferation and survival of somatic gonadal cells and in the maturation of oocytes or spermatozoa. We discuss also the role of AMPK in germ and somatic cell interactions within the cumulus-oocyte complex and in the blood testis barrier. Finally, the interface in the gonad between AMPK and modification of metabolism is reported and discussion about the role of AMPK on fertility, in regards to the treatment of infertility associated with insulin resistance (male obesity, polycystic ovary syndrome.

  6. Energy Status Determines Hindbrain Signal Transduction Pathway Transcriptional Reactivity to AMPK in the Estradiol-Treated Ovariectomized Female Rat

    Ibrahim, Baher A.; Alenazi, Fahaad S.H.; Briski, Karen P.

    2014-01-01

    Dorsal vagal complex (DVC) AMPK regulation of food intake in the estradiol-treated ovariectomized (OVX) female rat is energy state-dependent. Here, RT-PCR array technology was used to identify estradiol-sensitive AMPK-regulated DVC signal transduction pathways that exhibit differential reactivity to sensor activation during energy balance versus imbalance. The AMP mimetic AICAR correspondingly reduced or stimulated cDVC phosphoAMPK (pAMPK) and estrogen receptor-beta (ERβ) proteins in full-fed...

  7. The dark face of AMPK as an essential tumor promoter.

    Jeon, Sang-Min; Hay, Nissim

    2012-10-01

    Numerous studies have shown that supraphysiological activation of AMPK could inhibit tumor growth. On the other hand, accumulating data also suggest that AMPK activity is required for tumor growth and migration. These findings suggest that physiological activation of AMPK is critical for tumor growth/migration, possibly through maintenance of ATP levels. Our recent study provides the first evidence that the maintenance of cellular NADPH homeostasis is the predominant mechanism by which AMPK promotes tumor cell survival and solid tumor formation. We showed that AMPK activation is required to maintain intracellular NADPH levels through the activation of fatty acid oxidation (FAO) or the inhibition of fatty acid synthesis (FAS) during glucose deprivation or matrix detachment respectively. Through these processes AMPK activation inhibits the rise in reactive oxygen species (ROS) levels and promotes metabolic adaptation in response to metabolic stress. This finding also provides a new therapeutic opportunity through targeting metabolic adaptation of cancer cells, either alone or in combination with conventional anti-cancer drugs that cause metabolic stress. PMID:23676995

  8. 小檗碱影响 AMPK/PGC-1信号途径改善糖尿病胰岛素抵抗和线粒体功能的研究%Berberine improves insulin-resistance and mitochondrial function by activating AMP-activated ;protein kinase (AMPK)/PGC-1α pathway

    王会玲; 李燕; 胡伟锋; 田军; 张金元

    2014-01-01

    Objective To investigate Berberine improve metabolism and insulin resistant in db/db mice and effects on skeletal muscle mitochondrial function, and relative mechanisms. Methods We selected db/db mouse as model of diabetes/insulin-resistance, the wild type mouse as control group. The db/db mice were administrated with berberine(5 mg·kg-1·d-1) by intraperitoneal injection till three weeks. The food intake, body weight and fasting blood glucose levels were observed every week. At 3rd weekend, all the mice were sacrificed, blood serum sample was collected for measurement the fasting insulin level by ELISA, then calculation of insulin sensitivity index (ISI). The epididymal fat pads were separation and weighed. The gastrocnemius was extracted mitochondria and measured the cytochrome C oxidase activity and ATP content. The gastrocnemius AMPK/PGC-1-αexpression was detected by Western blot. Results The body weight and fat weight of db/db mice decreased dramatically after treated with berberine. Berberine showed lowering fast blood glucose and improving the ISI. No significant change in serum insulin release before or after Berberine treated. Berberine increased the COX activity and ATP content in skeletal muscle mitochondria. We also observed the AMPK phosphorylation was significantly activated and the nucleus transcriptional PGC-1αincreased. Conclusion Berberine obviously improved insulin-resistance by lower blood glucose, body weight and fat weight. These effects showed no relationship to insulin release, but related to increase mitochondria energy metabolism by active AMPK/PGC-1αsignaling.%目的:探讨小檗碱改善糖尿病鼠糖代谢及胰岛素抵抗作用及对骨骼肌线粒体功能的影响和机制。方法采用db/db小鼠为研究对象,以野生型小鼠为对照组。给予小檗碱(5 mg·kg-1·d-1)腹腔注射3周,观察食量、体重和空腹血糖水平;第3周末处死,留取血标本分离血清,检测胰岛素水平并计算

  9. Genetic and metabolic effects on skeletal muscle AMPK in young and older twins

    Mortensen, Brynjulf; Poulsen, Pernille; Wegner, Lise;

    2009-01-01

    The protein complex AMP-activated protein kinase (AMPK) is believed to play an important role in the regulation of skeletal muscle glucose and lipid metabolism. Defects in the AMPK system might therefore be an important factor in the pathogenesis of type 2 diabetes. We aimed to identify genetic and...... environmental mechanisms involved in the regulation of AMPK expression and activity and to examine the association between AMPK protein levels and activity on one hand, and glucose and fat metabolism on the other hand. We investigated skeletal muscle biopsies from 100 young and 82 older mono- and dizygotic non...... influence. AMPK gamma3 protein expression and activity were negatively related to whole-body glucose uptake through the non-oxidative metabolic pathway, and positively related to phosphorylation of glycogen synthase. In conclusion, our results suggest that skeletal muscle AMPK expression is under minor...

  10. A role for AMPK in the inhibition of glucose-6-phosphate dehydrogenase by polyunsaturated fatty acids

    Kohan, Alison B.; Talukdar, Indrani; Walsh, Callee M. [Department of Biochemistry, West Virginia University, Morgantown, WV (United States); Salati, Lisa M., E-mail: lsalati@hsc.wvu.edu [Department of Biochemistry, West Virginia University, Morgantown, WV (United States)

    2009-10-09

    Both polyunsaturated fatty acids and AMPK promote energy partitioning away from energy consuming processes, such as fatty acid synthesis, towards energy generating processes, such as {beta}-oxidation. In this report, we demonstrate that arachidonic acid activates AMPK in primary rat hepatocytes, and that this effect is p38 MAPK-dependent. Activation of AMPK mimics the inhibition by arachidonic acid of the insulin-mediated induction of G6PD. Similar to intracellular signaling by arachidonic acid, AMPK decreases insulin signal transduction, increasing Ser{sup 307} phosphorylation of IRS-1 and a subsequent decrease in AKT phosphorylation. Overexpression of dominant-negative AMPK abolishes the effect of arachidonic acid on G6PD expression. These data suggest a role for AMPK in the inhibition of G6PD by polyunsaturated fatty acids.

  11. The proteasome inhibitor bortezomib induces testicular toxicity by upregulation of oxidative stress, AMP-activated protein kinase (AMPK) activation and deregulation of germ cell development in adult murine testis.

    Li, Wei; Fu, Jianfang; Zhang, Shun; Zhao, Jie; Xie, Nianlin; Cai, Guoqing

    2015-06-01

    Understanding how chemotherapeutic agents mediate testicular toxicity is crucial in light of compelling evidence that male infertility, one of the severe late side effects of intensive cancer treatment, occurs more often than they are expected to. Previous study demonstrated that bortezomib (BTZ), a 26S proteasome inhibitor used to treat refractory multiple myeloma (MM), exerts deleterious impacts on spermatogenesis in pubertal mice via unknown mechanisms. Here, we showed that intermittent treatment with BTZ resulted in fertility impairment in adult mice, evidenced by testicular atrophy, desquamation of immature germ cells and reduced caudal sperm storage. These deleterious effects may originate from the elevated apoptosis in distinct germ cells during the acute phase and the subsequent disruption of Sertoli-germ cell anchoring junctions (AJs) during the late recovery. Mechanistically, balance between AMP-activated protein kinase (AMPK) activation and Akt/ERK pathway appeared to be indispensable for AJ integrity during the late testicular recovery. Of particular interest, the upregulated testicular apoptosis and the following disturbance of Sertoli-germ cell interaction may both stem from the excessive oxidative stress elicited by BTZ exposure. We also provided the in vitro evidence that AMPK-dependent mechanisms counteract follicle-stimulating hormone (FSH) proliferative effects in BTZ-exposed Sertoli cells. Collectively, BTZ appeared to efficiently prevent germ cells from normal development via multiple mechanisms in adult mice. Employment of antioxidants and/or AMPK inhibitor may represent an attractive strategy of fertility preservation in male MM patients exposed to conventional BTZ therapy and warrants further investigation. PMID:25886977

  12. HIGD1A Regulates Oxygen Consumption, ROS Production, and AMPK Activity during Glucose Deprivation to Modulate Cell Survival and Tumor Growth

    Kurosh Ameri

    2015-02-01

    Full Text Available Hypoxia-inducible gene domain family member 1A (HIGD1A is a survival factor induced by hypoxia-inducible factor 1 (HIF-1. HIF-1 regulates many responses to oxygen deprivation, but viable cells within hypoxic perinecrotic solid tumor regions frequently lack HIF-1α. HIGD1A is induced in these HIF-deficient extreme environments and interacts with the mitochondrial electron transport chain to repress oxygen consumption, enhance AMPK activity, and lower cellular ROS levels. Importantly, HIGD1A decreases tumor growth but promotes tumor cell survival in vivo. The human Higd1a gene is located on chromosome 3p22.1, where many tumor suppressor genes reside. Consistent with this, the Higd1a gene promoter is differentially methylated in human cancers, preventing its hypoxic induction. However, when hypoxic tumor cells are confronted with glucose deprivation, DNA methyltransferase activity is inhibited, enabling HIGD1A expression, metabolic adaptation, and possible dormancy induction. Our findings therefore reveal important new roles for this family of mitochondrial proteins in cancer biology.

  13. The polyphenol extract from Sechium edule shoots inhibits lipogenesis and stimulates lipolysis via activation of AMPK signals in HepG2 cells.

    Wu, Cheng-Hsun; Ou, Ting-Tsz; Chang, Chun-Hua; Chang, Xiao-Zong; Yang, Mon-Yuan; Wang, Chau-Jong

    2014-01-22

    Fatty liver may have implications for metabolic syndrome, such as obesity, hypertension, and diabetes. Therefore, the development of pharmacological or natural agents to reduce fat accumulation in the liver is an important effort. The Sechium edule shoots have already been verified to decrease serum lipids and cholesterol and prevent atherosclerosis. However, how Sechium edule shoots modulate hepatic lipid metabolism is unclear. This study was designed to investigate the effects and mechanisms of polyphenol extracts (SPE) of Sechium edule shoots in reducing lipid accumulation in oleic acid-treated HepG2 cells. We found that water extracts (SWE) of Sechium edule shoots could decrease serum and hepatic lipid contents (e.g., triacylglycerol and cholesterol). Furthermore, SWE and SPE through the AMPK (AMP-activating protein kinase) signaling pathway could decrease lipogenic relative enzymes, such as FAS (fatty acid synthase), HMGCoR (HMG-CoA reductase), and SREBPs (sterol regulatory element binding proteins), and increase the expression of CPT-I (carnitine palmitoyltransferase I) and PPARα (peroxisome proliferators activated receptor α), which are critical regulators of hepatic lipid metabolism. These observations suggested that Sechium edule shoots have potential for developing health foods for preventing and remedying fatty liver. PMID:24377368

  14. Targeting AMPK Signaling Pathway to Overcome Drug Resistance for Cancer Therapy.

    Wang, Zhiyu; Liu, Pengxi; Chen, Qianjun; Deng, Shigui; Liu, Xiaoyan; Situ, Honglin; Zhong, Shaowen; Hann, Swei; Lin, Yi

    2016-01-01

    Mulitdrug resistance (MDR) is one of critical factorslimiting the efficacy of cancer chemoor radiotherapy. Emerging evidence has indicated that MDR is a complex process regulated by multiple factors, among which stress response molecules are considered as central players. AMP-activated protein kinase (AMPK) is a major regulator balancing energy supply and ultimately protects cells from harmful stresses via coordinating multiple metabolic pathways Notably, AMPK activation was recently shown to mediate the metabolism reprogramming in drug resistant cancer cells including promoting Warburg effects and mitochondrial biogenesis. Furthermore, AMPK activity has also been shown to regulate the self-renewal ability of cancer stem cells that are often refractory to chemotherapy. In addition, AMPK phosphorylation was critical in mediating autophagy induction, a process demonstrated to be effective in chemosensitivity modulation via degrading cellular components to satisfy nutrients requirement under stressful condition. Meanwhile, drug discovery targeting AMPK has been developed to validate the pathological significance of AMPK in cancer prevention and treatment. Although conflicting evidence focusing on the AMPK modulation for cancer treatment is still remained, this might be attributed to differences in AMPK isotypes in specific tissues, off-targets effects, the degree and duration of drug administration and experimental setting of stress conditions. This review will focus on AMPK mediated resistance to cancer therapy and discuss its potential therapeutic implication and targeting drug development. PMID:25777274

  15. Perfluorooctanoic acid exposure alters polyunsaturated fatty acid composition, induces oxidative stress and activates the AKT/AMPK pathway in mouse epididymis.

    Lu, Yin; Pan, Yitao; Sheng, Nan; Zhao, Allan Z; Dai, Jiayin

    2016-09-01

    Perfluorooctanoic acid (PFOA) is a degradation-resistant compound with a carbon-fluorine bond. Although PFOA emissions have been reduced since 2000, it remains persistent in the environment. Several studies on laboratory animals indicate that PFOA exposure can impact male fertility. Here, adult male mice received either PFOA (1.25, 5 or 20 mg/kg/d) or an equal volume of water for 28 d consecutively. PFOA accumulated in the epididymis in a dose-dependent manner and resulted in reduced epididymis weight, lower levels of triglycerides (TG), cholesterol (CHO), and free fatty acids (FFA), and activated AKT/AMPK signaling in the epididymis. Altered polyunsaturated fatty acid (PUFA) compositions, such as a higher arachidonic acid:linoleic acid (AA:LA) ratio, concomitant with excessive oxidative stress, as demonstrated by increased malonaldehyde (MDA) and decreased glutathione peroxidase (GSH-Px) in the epididymis, were observed in epididymis tissue following treatment with PFOA. These results indicate that the epididymis is a potential target of PFOA. Oxidative stress and PUFA alteration might help explain the sperm injury and male reproductive dysfunction induced by PFOA exposure. PMID:27262104

  16. Resistance exercise-induced S6K1 kinase activity is not inhibited in human skeletal muscle despite prior activation of AMPK by high-intensity interval cycling

    Apró, William; Moberg, Marcus; Hamilton, D. Lee;

    2015-01-01

    hypothesis was tested in eight trained male subjects who in randomized order performed either resistance exercise only (R) or interval cycling followed by resistance exercise (ER). Biopsies taken from the vastus lateralis before and after endurance exercise and repeatedly after resistance exercise were......Combining endurance and strength training in the same session has been reported to reduce the anabolic response to the latter form of exercise. The underlying mechanism, based primarily on results from rodent muscle, is proposed to involve AMPK-dependent inhibition of mTORC1 signaling. This...

  17. Methylisoindigo preferentially kills cancer stem cells by interfering cell metabolism via inhibition of LKB1 and activation of AMPK in PDACs.

    Cheng, Xinlai; Kim, Jee Young; Ghafoory, Shahrouz; Duvaci, Tijen; Rafiee, Roya; Theobald, Jannick; Alborzinia, Hamed; Holenya, Pavlo; Fredebohm, Johannes; Merz, Karl-Heinz; Mehrabi, Arianeb; Hafezi, Mohammadreza; Saffari, Arash; Eisenbrand, Gerhard; Hoheisel, Jörg D; Wölfl, Stefan

    2016-06-01

    Pancreatic ductal adenocarcinoma (PDAC) clinically has a very poor prognosis. No small molecule is available to reliably achieve cures. Meisoindigo is chemically related to the natural product indirubin and showed substantial efficiency in clinical chemotherapy for CML in China. However, its effect on PDAC is still unknown. Our results showed strong anti-proliferation effect of meisoindigo on gemcitabine-resistant PDACs. Using a recently established primary PDAC cell line, called Jopaca-1 with a larger CSCs population as model, we observed a reduction of CD133+ and ESA+/CD44+/CD24+ populations upon treatment and concomitantly a decreased expression of CSC-associated genes, and reduced cellular mobility and sphere formation. Investigating basic cellular metabolic responses, we detected lower oxygen consumption and glucose uptake, while intracellular ROS levels increased. This was effectively neutralized by the addition of antioxidants, indicating an essential role of the cellular redox balance. Further analysis on energy metabolism related signaling revealed that meisoindigo inhibited LKB1, but activated AMPK. Both of them were involved in cellular apoptosis. Additional in situ hybridization in tissue sections of PDAC patients reproducibly demonstrated co-expression and -localization of LKB1 and CD133 in malignant areas. Finally, we detected that CD133+/CD44+ were more vulnerable to meisoindigo, which could be mimicked by LKB1 siRNAs. Our results provide the first evidence, to our knowledge, that LKB1 sustains the CSC population in PDACs and demonstrate a clear benefit of meisoindigo in treatment of gemcitabine-resistant cells. This novel mechanism may provide a promising new treatment option for PDAC. PMID:26887594

  18. 二甲双胍通过激活腺苷酸活化蛋白激酶(AMPK)的抗肿瘤机制%Antitumor Mechanism of Metformin via Adenosine Monophosphate-activated Protein Kinase (AMPK) Activation

    陈兆煜; 王连唐; 陈雁扬

    2013-01-01

    Metformin, as a traditional oral hypoglycemic agent, is commonly used in the clinical treatment for type 2 diabetes. Recently, a large number of epidemiological researches have shown that metformin could reduce the tumor morbidity of type 2 diabetes, moreover, it has also been indicated that metformin could inhibit the growth, proliferation and transformation of cancer cells in metabolic pathways, cell cycle, oxidative stress and cancer/tumor stem cells transformation via AMPK pathway activation. But the antitumor effect of metformin via AMPK activation still exists arguments, and the deifnite mechanism remains to be further investigated and conifrmed by extensive clinical trials.%二甲双胍是一种传统的口服降糖药,临床上普遍用于2型糖尿病的治疗。近年来大量流行病学研究报道二甲双胍能够降低2型糖尿病患者的肿瘤发病率,亦有研究发现二甲双胍能在代谢途径、细胞周期、氧化应激、肿瘤干细胞转化等方面通过激活腺苷酸活化蛋白激酶(adenosine monophosphate-activated protein kinase, AMPK)信号通路,从而抑制肿瘤细胞的生长、增殖以及转化。但二甲双胍通过激活AMPK的抗肿瘤机制仍存在着争议,其确切的作用机制有待进一步深入的研究,同时亟需大规模的临床试验来证实。

  19. Hypothalamic AMPK: a canonical regulator of whole-body energy balance.

    López, Miguel; Nogueiras, Rubén; Tena-Sempere, Manuel; Diéguez, Carlos

    2016-07-01

    AMP-activated protein kinase (AMPK) has a major role in the modulation of energy balance. AMPK is activated in conditions of low energy, increasing energy production and reducing energy consumption. The AMPK pathway is a canonical route regulating energy homeostasis by integrating peripheral signals, such as hormones and metabolites, with neuronal networks. Current evidence has implicated AMPK in the hypothalamus and hindbrain with feeding, brown adipose tissue thermogenesis and browning of white adipose tissue, through modulation of the sympathetic nervous system, as well as glucose homeostasis. Interestingly, several potential antiobesity and/or antidiabetic agents, some of which are currently in clinical use such as metformin and liraglutide, exert some of their actions by acting on AMPK. Furthermore, the orexigenic and weight-gain effects of commonly used antipsychotic drugs are also mediated by hypothalamic AMPK. Overall, this evidence suggests that hypothalamic AMPK signalling is an interesting target for drug development, but is this approach feasible? In this Review we discuss the current understanding of hypothalamic AMPK and its role in the central regulation of energy balance and metabolism. PMID:27199291

  20. AMPK is Involved in Mediation of Erythropoietin Influence on Metabolic Activity and Reactive Oxygen Species Production in White Adipocytes

    Wang, Li; Di, Lijun; Noguchi, Constance Tom

    2014-01-01

    Erythropoietin, discovered for its indispensable role during erythropoiesis, has been used in the therapy for selected red blood cell disorders in erythropoietin-deficient patients. The biological activities of erythropoietin have been found to extend to non-erythroid tissues due to the expression of erythropoietin receptor. We previously demonstrated that erythropoietin promotes metabolic activity and white adipocytes browning to increase mitochondrial function and energy expenditure via per...

  1. Cardiovascular Protective Effect of Metformin and Telmisartan: Reduction of PARP1 Activity via the AMPK-PARP1 Cascade

    Shang, Fenqing; Zhang, Jiao; Li, Zhao; Zhang, Jin; Yin, Yanjun; Wang, Yaqiong; Marin, Traci L.; Gongol, Brendan; Xiao, Han; Zhang, You-Yi; Chen, Zhen; Shyy, John Y-J; Lei, Ting

    2016-01-01

    Hyperglycemia and hypertension impair endothelial function in part through oxidative stress-activated poly (ADP-ribose) polymerase 1 (PARP1). Biguanides and angiotensin II receptor blockers (ARBs) such as metformin and telmisartan have a vascular protective effect. We used cultured vascular endothelial cells (ECs), diabetic and hypertensive rodent models, and AMPKα2-knockout mice to investigate whether metformin and telmisartan have a beneficial effect on the endothelium via AMP-activated pro...

  2. Fenofibrate Improves Renal Lipotoxicity through Activation of AMPK-PGC-1α in db/db Mice

    Yu Ah Hong; Ji Hee Lim; Min Young Kim; Tae Woo Kim; Yaeni Kim; Keun Suk Yang; Hoon Suk Park; Sun Ryoung Choi; Sungjin Chung; Hyung Wook Kim; Hye Won Kim; Bum Soon Choi; Yoon Sik Chang; Cheol Whee Park

    2014-01-01

    Peroxisome proliferator-activated receptor (PPAR)-α, a lipid-sensing transcriptional factor, serves an important role in lipotoxicity. We evaluated whether fenofibrate has a renoprotective effect by ameliorating lipotoxicity in the kidney. Eight-week-old male C57BLKS/J db/m control and db/db mice, divided into four groups, received fenofibrate for 12 weeks. In db/db mice, fenofibrate ameliorated albuminuria, mesangial area expansion and inflammatory cell infiltration. Fenofibrate inhibited ac...

  3. α-MSH Stimulates Glucose Uptake in Mouse Muscle and Phosphorylates Rab-GTPase-Activating Protein TBC1D1 Independently of AMPK

    Enriori, Pablo J.; Jensen, Thomas Elbenhardt; Garcia-Rudaz, Cecilia; Litwak, Sara A.; Raun, Kirsten; Wojtaszewski, Jørgen; Wulff, Birgitte Schjellerup; Cowley, Michael A.

    2016-01-01

    The melanocortin system includes five G-protein coupled receptors (family A) defined as MC1R-MC5R, which are stimulated by endogenous agonists derived from proopiomelanocortin (POMC). The melanocortin system has been intensely studied for its central actions in body weight and energy expenditure regulation, which are mainly mediated by MC4R. The pituitary gland is the source of various POMC-derived hormones released to the circulation, which raises the possibility that there may be actions of the melanocortins on peripheral energy homeostasis. In this study, we examined the molecular signaling pathway involved in α-MSH-stimulated glucose uptake in differentiated L6 myotubes and mouse muscle explants. In order to examine the involvement of AMPK, we investigate α-MSH stimulation in both wild type and AMPK deficient mice. We found that α-MSH significantly induces phosphorylation of TBC1 domain (TBC1D) family member 1 (S237 and T596), which is independent of upstream PKA and AMPK. We find no evidence to support that α-MSH-stimulated glucose uptake involves TBC1D4 phosphorylation (T642 and S704) or GLUT4 translocation. PMID:27467141

  4. Argininosuccinate synthetase regulates hepatic AMPK linking protein catabolism and ureagenesis to hepatic lipid metabolism.

    Madiraju, Anila K; Alves, Tiago; Zhao, Xiaojian; Cline, Gary W; Zhang, Dongyan; Bhanot, Sanjay; Samuel, Varman T; Kibbey, Richard G; Shulman, Gerald I

    2016-06-14

    A key sensor of cellular energy status, AMP-activated protein kinase (AMPK), interacts allosterically with AMP to maintain an active state. When active, AMPK triggers a metabolic switch, decreasing the activity of anabolic pathways and enhancing catabolic processes such as lipid oxidation to restore the energy balance. Unlike oxidative tissues, in which AMP is generated from adenylate kinase during states of high energy demand, the ornithine cycle enzyme argininosuccinate synthetase (ASS) is a principle site of AMP generation in the liver. Here we show that ASS regulates hepatic AMPK, revealing a central role for ureagenesis flux in the regulation of metabolism via AMPK. Treatment of primary rat hepatocytes with amino acids increased gluconeogenesis and ureagenesis and, despite nutrient excess, induced both AMPK and acetyl-CoA carboxylase (ACC) phosphorylation. Antisense oligonucleotide knockdown of hepatic ASS1 expression in vivo decreased liver AMPK activation, phosphorylation of ACC, and plasma β-hydroxybutyrate concentrations. Taken together these studies demonstrate that increased amino acid flux can activate AMPK through increased AMP generated by ASS, thus providing a novel link between protein catabolism, ureagenesis, and hepatic lipid metabolism. PMID:27247419

  5. Genome-wide inhibitory impact of the AMPK activator metformin on [kinesins, tubulins, histones, auroras and polo-like kinases] M-phase cell cycle genes in human breast cancer cells.

    Oliveras-Ferraros, Cristina; Vazquez-Martin, Alejandro; Menendez, Javier A

    2009-05-15

    Prompted by the ever-growing scientific rationale for examining the antidiabetic drug metformin as a potential antitumor agent in breast cancer disease, we recently tested the hypothesis that the assessment of metformin-induced global changes in gene expression-as identified using 44 K (double density) Agilent's whole human genome arrays-could reveal gene-expression signatures that would allow proper selection of breast cancer patients who should be considered for metformin-based clinical trials. Using Database for Annotation, Visualization and Integrated Discovery bioinformatics (DAVID) resources we herein reveal that, at doses that lead to activation of the AMP-activated protein kinase (AMPK), metformin not only downregulates genes coding for ribosomal proteins (i.e., protein and macromolecule biosynthesis) but unexpectedly suppresses numerous mitosis-related gene families including kinesins, tubulins, histones, auroras and polo-like kinases. This is, to our knowledge, the first genome-scale evidence of a mitotic core component in the transcriptional response of human breast cancer cells to metformin. These findings further support a tight relationship between the activation status of AMPK and the chromosomal and cytoskeletal checkpoints of cell mitosis at the transcriptional level. PMID:19372741

  6. Thiamine deficiency induces anorexia by inhibiting hypothalamic AMPK.

    Liu, M; Alimov, A P; Wang, H; Frank, J A; Katz, W; Xu, M; Ke, Z-J; Luo, J

    2014-05-16

    Obesity and eating disorders are prevailing health concerns worldwide. It is important to understand the regulation of food intake and energy metabolism. Thiamine (vitamin B1) is an essential nutrient. Thiamine deficiency (TD) can cause a number of disorders in humans, such as Beriberi and Wernicke-Korsakoff syndrome. We demonstrated here that TD caused anorexia in C57BL/6 mice. After feeding a TD diet for 16days, the mice displayed a significant decrease in food intake and an increase in resting energy expenditure (REE), which resulted in a severe weight loss. At the 22nd day, the food intake was reduced by 69% and 74% for male and female mice, respectively in TD group. The REE increased by ninefolds in TD group. The loss of body weight (17-24%) was similar between male and female animals and mainly resulted from the reduction of fat mass (49% decrease). Re-supplementation of thiamine (benfotiamine) restored animal's appetite, leading to a total recovery of body weight. The hypothalamic adenosine monophosphate-activated protein kinase (AMPK) is a critical regulator of food intake. TD inhibited the phosphorylation of AMPK in the arcuate nucleus (ARN) and paraventricular nucleus (PVN) of the hypothalamus without affecting its expression. TD-induced inhibition of AMPK phosphorylation was reversed once thiamine was re-supplemented. In contrast, TD increased AMPK phosphorylation in the skeletal muscle and upregulated the uncoupling protein (UCP)-1 in brown adipose tissues which was consistent with increased basal energy expenditure. Re-administration of thiamine stabilized AMPK phosphorylation in the skeletal muscle as well as energy expenditure. Taken together, TD may induce anorexia by inhibiting hypothalamic AMPK activity. With a simultaneous increase in energy expenditure, TD caused an overall body weight loss. The results suggest that the status of thiamine levels in the body may affect food intake and body weight. PMID:24607345

  7. AMPK signaling in skeletal muscle during exercise: Role of reactive oxygen and nitrogen species.

    Morales-Alamo, David; Calbet, Jose A L

    2016-09-01

    Reactive oxygen and nitrogen species (RONS) are generated during exercise depending on intensity, duration and training status. A greater amount of RONS is released during repeated high-intensity sprint exercise and when the exercise is performed in hypoxia. By activating adenosine monophosphate-activated kinase (AMPK), RONS play a critical role in the regulation of muscle metabolism but also in the adaptive responses to exercise training. RONS may activate AMPK by direct an indirect mechanisms. Directly, RONS may activate or deactivate AMPK by modifying RONS-sensitive residues of the AMPK-α subunit. Indirectly, RONS may activate AMPK by reducing mitochondrial ATP synthesis, leading to an increased AMP:ATP ratio and subsequent Thr(172)-AMPK phosphorylation by the two main AMPK kinases: LKB1 and CaMKKβ. In presence of RONS the rate of Thr(172)-AMPK dephosphorylation is reduced. RONS may activate LKB1 through Sestrin2 and SIRT1 (NAD(+)/NADH.H(+)-dependent deacetylase). RONS may also activate CaMKKβ by direct modification of RONS sensitive motifs and, indirectly, by activating the ryanodine receptor (Ryr) to release Ca(2+). Both too high (hypoxia) and too low (ingestion of antioxidants) RONS levels may lead to Ser(485)-AMPKα1/Ser(491)-AMPKα2 phosphorylation causing inhibition of Thr(172)-AMPKα phosphorylation. Exercise training increases muscle antioxidant capacity. When the same high-intensity training is applied to arm and leg muscles, arm muscles show signs of increased oxidative stress and reduced mitochondrial biogenesis, which may be explained by differences in RONS-sensing mechanisms and basal antioxidant capacities between arm and leg muscles. Efficient adaptation to exercise training requires optimal exposure to pulses of RONS. Inappropriate training stimulus may lead to excessive RONS formation, oxidative inactivation of AMPK and reduced adaptation or even maladaptation. Theoretically, exercise programs should be designed taking into account the

  8. AMPK β1 Deletion Reduces Appetite, Preventing Obesity and Hepatic Insulin Resistance*

    Dzamko, Nicolas; Van Denderen, Bryce J.W.; Hevener, Andrea L.; Jørgensen, Sebastian Beck; Honeyman, Jane; Galic, Sandra; Chen, Zhi-Ping; Watt, Matthew J.; Campbell, Duncan J.; Steinberg, Gregory R.; Kemp, Bruce E.

    2009-01-01

    The AMP-activated protein kinase (AMPK) is an αβγ heterotrimer that regulates appetite and fuel metabolism. We have generated AMPK β1−/− mice on a C57Bl/6 background that are viable, fertile, survived greater than 2 years, and display no visible brain developmental defects. These mice have a 90% reduction in hepatic AMPK activity due to loss of the catalytic α subunits, with modest reductions of activity detected in the hypothalamus and white adipose tissue and no change in skeletal muscle or...

  9. AMPK inhibition blocks ROS-NFκB signaling and attenuates endotoxemia-induced liver injury.

    Yuan Guo

    Full Text Available BACKGROUND: AMP-activated protein kinase (AMPK is an important enzyme in regulation of cellular energy homeostasis. We have previously shown that AMPK activation by 5-aminoimidazole-4-carboxamide (AICAR results in suppression of immune responses, indicating the pivotal role of AMPK in immune regulation. However, the cellular mechanism underpinning AMPK inhibition on immune response remains largely to be elucidated. The study aimed to investigate the effects of AMPK inhibition on reactive oxygen species (ROS-nuclear factor κB (NFκB signaling and endotoxemia-induced liver injury. METHODOLOGY/PRINCIPAL FINDINGS: RAW 264.7 cells were pretreated with AMPK activator or inhibitor, followed by LPS challenge. In addition, LPS was injected intraperitoneally into mice to induce systemic inflammation. The parameters of liver injury and immune responses were determined, and survival of mice was monitored respectively. LPS challenge in RAW 264.7 cells resulted in AMPK activation which was then inhibited by compound C treatment. Both AMPK activation by AICAR or inhibition by compound C diminished LPS-induced ROS generation, inhibited phosphorylation of IKK, IκB, and NFκB p65, and consequently, decreased TNF production of RAW 264.7 cells. AICAR or compound C treatment decreased ALT, AST, and TNF levels in serum, reduced CD68 expression and MPO activity in liver tissue of mice with endotoxemia. Moreover, AICAR or compound C treatment improved survival of endotoxemic mice. CONCLUSIONS: AICAR or compound C treatment attenuates LPS-induced ROS-NFκB signaling, immune responses and liver injury. Strategies to activate or inhibit AMPK signaling may provide alternatives to the current clinical approaches to inhibit immune responses of endotoxemia.

  10. Chitosan oligosaccharide suppresses tumor progression in a mouse model of colitis-associated colorectal cancer through AMPK activation and suppression of NF-κB and mTOR signaling.

    Mattaveewong, Tharinee; Wongkrasant, Preedajit; Chanchai, Sumalee; Pichyangkura, Rath; Chatsudthipong, Varanuj; Muanprasat, Chatchai

    2016-07-10

    Novel, effective and safe agents are needed for the chemoprevention of colorectal cancer (CRC). This study investigated the effects of chitosan oligosaccharides (COS) on CRC progression and their underlying mechanisms and safety profiles in mice. Using a mouse model of colitis-associated CRC, we found that oral administration of COS (500mg/kg/day) resulted in a ∼60% reduction of tumor size and tumor numbers/sectioning. In addition, COS treatment increased AMPK activity, suppressed the NF-κB-mediated inflammatory response and reduced the expressions of cyclin D1, phosphorylated ribosomal protein S6, and MMP-9 in the colon tissues of these mice. Importantly, administration of COS (500mg/kg/day; 50 days) had no adverse effects on renal or liver functions. Our results indicate that COS suppressed CRC progression via AMPK activation and the suppression of NF-κB and mTOR signaling. COS may be of potential utility in the chemoprevention of CRC. PMID:27106148

  11. PP2A mediated AMPK inhibition promotes HSP70 expression in heat shock response.

    Ting Wang

    Full Text Available BACKGROUND: Under stress, AMP-activated protein kinase (AMPK plays a central role in energy balance, and the heat shock response is a protective mechanism for cell survival. The relationship between AMPK activity and heat shock protein (HSP expression under stress is unclear. METHODOLOGY/PRINCIPAL FINDINGS: We found that heat stress induced dephosphorylation of AMPKα subunit (AMPKα in various cell types from human and rodent. In HepG2 cells, the dephosphorylation of AMPKα under heat stress in turn caused dephosphorylation of acetyl-CoA carboxylase and upregulation of phosphoenolpyruvate carboxykinase, two downstream targets of AMPK, confirming the inhibition of AMPK activity by heat stress. Treatment of HepG2 cells with phosphatase 2A (PP2A inhibitor okadaic acid or inhibition of PP2A expression by RNA interference efficiently reversed heat stress-induced AMPKα dephosphorylation, suggesting that heat stress inhibited AMPK through activation of PP2A. Heat stress- and other HSP inducer (CdCl(2, celastrol, MG132-induced HSP70 expression could be inhibited by AICAR, an AMPK specific activator. Inhibition of AMPKα expression by RNA interference reversed the inhibitory effect of AICAR on HSP70 expression under heat stress. These results indicate that AMPK inhibition under stress contribute to HSP70 expression. Mechanistic studies showed that activation of AMPK by AICAR had no effect on heat stress-induced HSF1 nuclear translocation, phosphorylation and binding with heat response element in the promoter region of HSP70 gene, but significantly decreased HSP70 mRNA stability. CONCLUSIONS/SIGNIFICANCE: These results demonstrate that during heat shock response, PP2A mediated AMPK inhibition upregulates HSP70 expression at least partially through stabilizing its mRNA, which suggests a novel mechanism for HSP induction under stress.

  12. AMPK/Snf1 signaling regulates histone acetylation: Impact on gene expression and epigenetic functions.

    Salminen, Antero; Kauppinen, Anu; Kaarniranta, Kai

    2016-08-01

    AMP-activated protein kinase (AMPK) and its yeast homolog, Snf1, are critical regulators in the maintenance of energy metabolic balance not only stimulating energy production but also inhibiting energy-consuming processes. The AMPK/Snf1 signaling controls energy metabolism by specific phosphorylation of many metabolic enzymes and transcription factors, enhancing or suppressing their functions. The AMPK/Snf1 complexes can be translocated from cytoplasm into nuclei where they are involved in the regulation of transcription. Recent studies have indicated that AMPK/Snf1 activation can control histone acetylation through different mechanisms affecting not only gene transcription but also many other epigenetic functions. For instance, AMPK/Snf1 enzymes can phosphorylate the histone H3S10 (yeast) and H2BS36 (mammalian) sites which activate specific histone acetyltransferases (HAT), consequently enhancing histone acetylation. Moreover, nuclear AMPK can phosphorylate type 2A histone deacetylases (HDAC), e.g. HDAC4 and HDAC5, triggering their export from nuclei thus promoting histone acetylation reactions. AMPK activation can also increase the level of acetyl CoA, e.g. by inhibiting fatty acid and cholesterol syntheses. Acetyl CoA is a substrate for HATs, thus increasing their capacity for histone acetylation. On the other hand, AMPK can stimulate the activity of nicotinamide phosphoribosyltransferase (NAMPT) which increases the level of NAD(+). NAD(+) is a substrate for nuclear sirtuins, especially for SIRT1 and SIRT6, which deacetylate histones and transcription factors, e.g. those regulating ribosome synthesis and circadian clocks. Histone acetylation is an important epigenetic modification which subsequently can affect chromatin remodeling, e.g. via bromodomain proteins. We will review the signaling mechanisms of AMPK/Snf1 in the control of histone acetylation and subsequently clarify their role in the epigenetic regulation of ribosome synthesis and circadian clocks

  13. Carnosol, a dietary diterpene, displays growth inhibitory effects in human prostate cancer PC3 cells leading to G2-phase cell cycle arrest and targets the 5'-AMP-activated protein kinase (AMPK) pathway

    Johnson, Jeremy J.; Syed, Deeba N.; Heren, Chenelle R.; Suh, Yewseok; Adhami, Vaqar M.; Mukhtar, Hasan

    2010-01-01

    Purpose The anti-cancer effect of carnosol was investigated in human prostate cancer PC3 cells. Methods Biochemical analysis and protein array data of carnosol treated PC3 cells were analyzed. Results We evaluated carnosol for its potential anti-cancer properties in the PC3 cells. Using an MTT assay we found that carnosol (10 – 70 µM) decreases cell viability in a time and dose dependent manner. Next, we evaluated the effect of carnosol (20–60 uM) effect using flow cytometry as well as biochemical analysis and found induction of G2-phase cell cycle arrest. To establish a more precise mechanism, we performed a protein array that evaluated 638 proteins involved in cell signaling pathways. The protein array identified 5'-AMP-activated protein kinase (AMPK), a serine/threonine protein kinase involved in the regulation of cellular energy balance as a potential target. Further downstream effects consistent with cancer inhibition included the modulation of the mTOR/HSP70S6k/4E-BP1 pathway. Additionally, we found that carnosol targeted the PI3K/Akt pathway in a dose dependent manner. Conclusions These results suggest that carnosol targets multiple signaling pathways that include the AMPK pathway. The ability of carnosol to inhibit prostate cancer in vitro suggests carnosol may be a novel agent for the management of PCa. PMID:18286356

  14. Bezafibrate enhances proliferation and differentiation of osteoblastic MC3T3-E1 cells via AMPK and eNOS activation

    Xing ZHONG; Ling-ling XIU; Guo-hong WEI; Yuan-yuan LIU; Lei SU; Xiao-pei CAO; Yan-bing LI; Hai-peng XIAO

    2011-01-01

    Aim: To investigate the effects of bezafibrate on the proliferation and differentiation of osteoblastic MC3T3-E1 cells, and to determine the signaling pathway underlying the effects.Methods: MC3T3-E1 cells, a mouse osteoblastic cell line, were used. Cell viability and proliferation were examined using MTT assay and colorimetric BrdU incorporation assay, respectively. NO production was evaluated using the Griess reagent. The mRNA expression of ALP, collagen I, osteocalcin, BMP-2, and Runx-2 was measured using real-time PCR. Western blot analysis was used to detect the expression of AMPK and eNOS proteins.Results: Bezafibrate increased the viability and proliferation of MC3T3-E1 cells in a dose- and time-dependent manner. Bezafibrate (100 μmol/L) significantly enhanced osteoblastic mineralization and expression of the differentiation markers ALP, collagen I and osteocalcin. Bezaflbrate (100 μmol/L) increased phosphorylation of AMPK and eNOS, which led to an increase of NO production by 4.08-fold, and upregulating BMP-2 and Runx-2 mRNA expression. These effects could be blocked by AMPK inhibitor compound C (5 μmol/L), or the PPARβ inhibitor GSK0660 (0.5 μmol/L), but not by the PPARa inhibitor MK886 (10 μmol/L). Furthermore, GSK0660, compound C, or N-nitro-L-arginine methyl ester hydrochloride (L-NAME, 1 mmol/L) could reverse the stimulatory effects of bezafibrate (100 pmol/L) on osteoblast proliferation and differentiation, whereas MK886 only inhibited bezafibrate-induced osteoblast prolifera-tion.Conclusion: Bezafibrate stimulates proliferation and differentiation of MC3T3-E1 cells, mainly via a PPARβ-dependent mechanism. The drug might be beneficial for osteoporosis by promoting bone formation.

  15. Antagonistic control of muscle cell size by AMPK and mTORC1.

    Mounier, Rémi; Lantier, Louise; Leclerc, Jocelyne; Sotiropoulos, Athanassia; Foretz, Marc; Viollet, Benoit

    2011-08-15

    Nutrition and physical activity have profound effects on skeletal muscle metabolism and growth. Regulation of muscle mass depends on a thin balance between growth-promoting and growth-suppressing factors. Over the past decade, the mammalian target of rapamycin (mTOR) kinase has emerged as an essential factor for muscle growth by mediating the anabolic response to nutrients, insulin, insulin-like growth factors and resistance exercise. As opposed to the mTOR signaling pathway, the AMP-activated protein kinase (AMPK) is switched on during starvation and endurance exercise to upregulate energy-conserving processes. Recent evidence indicates that mTORC1 (mTOR Complex 1) and AMPK represent two antagonistic forces governing muscle adaption to nutrition, starvation and growth stimulation. Animal knockout models with impaired mTORC1 signaling showed decreased muscle mass correlated with increased AMPK activation. Interestingly, AMPK inhibition in p70S6K-deficient muscle cells restores cell growth and sensitivity to nutrients. Conversely, muscle cells lacking AMPK have increased mTORC1 activation with increased cell size and protein synthesis rate. We also demonstrated that the hypertrophic action of MyrAkt is enhanced in AMPK-deficient muscle, indicating that AMPK acts as a negative feedback control to restrain muscle hypertrophy. Our recent results extend this notion by showing that AMPKα1, but not AMPKα2, regulates muscle cell size through the control of mTORC1 signaling. These results reveal the diverse functions of the two catalytic isoforms of AMPK, with AMPKα1 playing a predominant role in the control of muscle cell size and AMPKα2 mediating muscle metabolic adaptation. Thus, the crosstalk between AMPK and mTORC1 signaling is a highly regulated way to control changes in muscle growth and metabolic rate imposed by external cues. PMID:21799304

  16. Inhibition of AMPK expression in skeletal muscle by systemic inflammation in COPD rats

    Qi, Yong; Shang, Jun-yi; Ma, Li-Jun; Sun, Bei-Bei; Hu, Xin-gang; Liu, Bao; Zhang, Guo-Jun

    2014-01-01

    Background Chronic obstructive pulmonary disease (COPD) is a disease characterized by airflow limitation and inflammation. Meanwhile, COPD also is associated with metabolic disorders, such as skeletal muscle weakness. Strikingly, activation of AMP-activated protein kinase (AMPK) exerts critical roles in energy metabolism. However, it remains unclear whether and how the expression levels of AMPK are affected in the COPD model rats which may lead to the dysfunction of the skeletal muscle in the...

  17. Berberine regulates neurite outgrowth through AMPK-dependent pathways by lowering energy status

    As a widely used anti-bacterial agent and a metabolic inhibitor as well as AMP-activated protein kinase (AMPK) activator, berberine (BBR) has been shown to cross the blood–brain barrier. Its efficacy has been investigated in various disease models of the central nervous system. Neurite outgrowth is critical for nervous system development and is a highly energy-dependent process regulated by AMPK-related pathways. In the present study, we aimed to investigate the effects of BBR on AMPK activation and neurite outgrowth in neurons. The neurite outgrowth of primary rat cortical neurons at different stages of polarization was monitored after exposure of BBR. Intracellular energy level, AMPK activation and polarity-related pathways were also inspected. The results showed that BBR suppressed neurite outgrowth and affected cytoskeleton stability in the early stages of neuronal polarization, which was mediated by lowered energy status and AMPK activation. Liver kinase B1 and PI3K–Akt–GSK3β signaling pathways were also involved. In addition, mitochondrial dysfunction and endoplasmic reticulum stress contributed to the lowered energy status induced by BBR. This study highlighted the knowledge of the complex activities of BBR in neurons and corroborated the significance of energy status during the neuronal polarization. - Highlights: • BBR inhibited neurite outgrowth in early stages of neuronal development. • Lowered neuronal energy status was induced by BBR treatment. • Neuronal energy stress induced by BBR activated AMPK-related pathways. • BBR induced mitochondrial dysfunction and endoplasmic reticulum stress

  18. Berberine regulates neurite outgrowth through AMPK-dependent pathways by lowering energy status

    Lu, Jiaqi; Cao, Yuanzhao; Cheng, Kuoyuan; Xu, Bo; Wang, Tianchang; Yang, Qi; Yang, Qin [State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing (China); Feng, Xudong, E-mail: xudong.feng@childrens.harvard.edu [Department of Medicine, Children' s Hospital Boston, Harvard Medical School, 300 Longwood Ave, Boston, MA 02115 (United States); Xia, Qing, E-mail: xqing@hsc.pku.edu.cn [State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing (China)

    2015-06-10

    As a widely used anti-bacterial agent and a metabolic inhibitor as well as AMP-activated protein kinase (AMPK) activator, berberine (BBR) has been shown to cross the blood–brain barrier. Its efficacy has been investigated in various disease models of the central nervous system. Neurite outgrowth is critical for nervous system development and is a highly energy-dependent process regulated by AMPK-related pathways. In the present study, we aimed to investigate the effects of BBR on AMPK activation and neurite outgrowth in neurons. The neurite outgrowth of primary rat cortical neurons at different stages of polarization was monitored after exposure of BBR. Intracellular energy level, AMPK activation and polarity-related pathways were also inspected. The results showed that BBR suppressed neurite outgrowth and affected cytoskeleton stability in the early stages of neuronal polarization, which was mediated by lowered energy status and AMPK activation. Liver kinase B1 and PI3K–Akt–GSK3β signaling pathways were also involved. In addition, mitochondrial dysfunction and endoplasmic reticulum stress contributed to the lowered energy status induced by BBR. This study highlighted the knowledge of the complex activities of BBR in neurons and corroborated the significance of energy status during the neuronal polarization. - Highlights: • BBR inhibited neurite outgrowth in early stages of neuronal development. • Lowered neuronal energy status was induced by BBR treatment. • Neuronal energy stress induced by BBR activated AMPK-related pathways. • BBR induced mitochondrial dysfunction and endoplasmic reticulum stress.

  19. Phytochemical regulation of Fyn and AMPK signaling circuitry.

    Lee, Chan Gyu; Koo, Ja Hyun; Kim, Sang Geon

    2015-12-01

    During the past decades, phytochemical terpenoids, polyphenols, lignans, flavonoids, and alkaloids have been identified as antioxidative and cytoprotective agents. Adenosine monophosphate-activated protein kinase (AMPK) is a kinase that controls redox-state and oxidative stress in the cell, and serves as a key molecule regulating energy metabolism. Many phytochemicals directly or indirectly alter the AMPK pathway in distinct manners, exerting catabolic metabolism. Some of them are considered promising in the treatment of metabolic diseases such as type II diabetes, obesity, and hyperlipidemia. Another important kinase that regulates energy metabolism is Fyn kinase, a member of the Src family kinases that plays a role in various cellular responses such as insulin signaling, cell growth, oxidative stress and apoptosis. Phytochemical inhibition of Fyn leads to AMPK-mediated protection of the cell in association with increased antioxidative capacity and mitochondrial biogenesis. The kinases may work together to form a signaling circuitry for the homeostasis of energy conservation and expenditure, and may serve as targets of phytochemicals. This review is intended as a compilation of recent advancements in the pharmacological research of phytochemicals targeting Fyn and AMPK circuitry, providing information for the prevention and treatment of metabolic diseases and the accompanying tissue injuries. PMID:25951818

  20. Cafeteria diet-induced insulin resistance is not associated with decreased insulin signaling or AMPK activity and is alleviated by physical training in rats

    Brandt, Nina; De Bock, Katrien; Richter, Erik;

    2010-01-01

    counteracted by training. In the perfused hindlimb, insulin-stimulated glucose transport in red gastrocnemius muscle was completely abolished in CAF and rescued by exercise training. Apart from a tendency toward an approximately 20% reduction in both basal and insulin-stimulated Akt Ser(473) phosphorylation (P......) among the groups. In conclusion, surplus energy intake of a palatable but low-fat cafeteria diet resulted in obesity and insulin resistance that was rescued by exercise training. Interestingly, insulin resistance was not accompanied by major defects in the insulin-signaling cascade or in altered AMPK......Excess energy intake via a palatable low-fat diet (cafeteria diet) is known to induce obesity and glucose intolerance in rats. However, the molecular mechanisms behind this adaptation are not known, and it is also not known whether exercise training can reverse it. Male Wistar rats were assigned to...

  1. AMPK: a master energy regulator for gonadal function

    Bertoldo, Michael J.; Faure, Melanie; Dupont, Joëlle; Froment, Pascal

    2015-01-01

    From C. elegans to mammals (including humans), nutrition and energy metabolism significantly influence reproduction. At the cellular level, some detectors of energy status indicate whether energy reserves are abundant (obesity), or poor (diet restriction). One of these detectors is AMPK (5′ AMP-activated protein kinase), a protein kinase activated by ATP deficiency but also by several natural substances such as polyphenols or synthetic molecules like metformin, used in the treatment of insuli...

  2. AMPK : a master energy regulator for gonadal functions.

    Michael eBertoldo; Melanie eFaure; Joëlle eDupont; Pascal eFroment

    2015-01-01

    From c.elegans to mammals (including humans), nutrition and energy metabolism strongly influence reproduction. At the cellular level, some detectors of energy status indicate whether energy reserves are abundant (obesity), or poor (diet restriction). One of these detectors is AMPK (5 'AMP-activated protein kinase), a protein kinase activated by ATP deficiency but also by several natural substances such as polyphenols or synthetic molecules like metformin, used in the treatment of insulin resi...

  3. AMPK controls exercise endurance, mitochondrial oxidative capacity, and skeletal muscle integrity

    Lantier, Louise; Fentz, Joachim; Mounier, Rémi;

    2014-01-01

    AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that plays a central role in skeletal muscle metabolism. We used skeletal muscle-specific AMPKα1α2 double-knockout (mdKO) mice to provide direct genetic evidence of the physiological importance of AMPK in regulating muscle...... as an elevated expression of interleukin 6 (IL-6) mRNA, possibly consistent with mild skeletal muscle injury. Notably, we found that AMPKα1 and AMPKα2 isoforms are dispensable for contraction-induced skeletal muscle glucose transport, except for male soleus muscle. However, the lack of skeletal...... muscle AMPK diminished maximal ADP-stimulated mitochondrial respiration, showing an impairment at complex I. This effect was not accompanied by changes in mitochondrial number, indicating that AMPK regulates muscle metabolic adaptation through the regulation of muscle mitochondrial oxidative capacity and...

  4. Contributions of AMPK and p53 dependent signaling to radiation response in the presence of metformin

    Background and purpose: Metformin is commonly prescribed to treat type 2 diabetes, and has additional potential as a cancer prophylactic and therapeutic. Metformin activates AMPK that in turn can launch a p53-dependent metabolic checkpoint. Possible interactions between metformin and radiation are poorly understood. Since radiation-induced signaling also involves AMPK and p53, we investigated their importance in mediating responses to metformin and radiation. Materials and methods: A549 cells, HCT116 cells wildtype or knockout for p53 or MEFs wildtype or double knockout for AMPKα1 and α2 were irradiated in the presence or absence of metformin. The impact of metformin on oxygen consumption and proliferation rates was determined, as well as clonogenic radiation survival. Results: Metformin resulted in moderate radiation protection in all cell lines, irrespective of AMPK and p53. Loss of AMPK sensitized cells to the anti-proliferative effects of metformin, while loss of p53 promoted both the growth inhibitory and toxic effects of metformin. Consequently, overall cell death after radiation was similar with and without metformin irrespective of AMPK or p53 genotype. Conclusions: The anti-proliferative activity of metformin may confer benefit in combination with radiotherapy, and this benefit is intensified upon loss of AMPK or p53 signaling

  5. Expanding roles for AMPK in skeletal muscle plasticity

    Mounier, Rémi; Théret, Marine; Lantier, Louise; Foretz, Marc; Viollet, Benoit

    2015-01-01

    Skeletal muscle possesses a remarkable plasticity and responds to environmental and physiological challenges by changing its phenotype in terms of size, composition, and metabolic properties. Muscle fibers rapidly adapt to drastic changes in energy demands during exercise through fine-tuning of the balance between catabolic and anabolic processes. One major sensor of energy demand in exercising muscle is AMP-activated protein kinase (AMPK). Recent advances have shed new light on the relevance...

  6. AMPK Control of Fat Metabolism in Skeletal Muscle

    Thomson, David M.; Winder, William W.

    2009-01-01

    AMP-activated protein kinase (AMPK) has emerged as a key regulator of skeletal muscle fat metabolism. Because abnormalities in skeletal muscle metabolism contribute to a variety of clinical diseases and disorders, understanding AMPK’s role in the muscle is important. It was originally shown to stimulate fatty acid oxidation decades ago, and since then much research has been accomplished describing this role. In this brief review we summarize much of this data, particularly in relation to chan...

  7. Myeloid Deletion of α1AMPK Exacerbates Atherosclerosis in LDL Receptor Knockout (LDLRKO) Mice.

    Cao, Qiang; Cui, Xin; Wu, Rui; Zha, Lin; Wang, Xianfeng; Parks, John S; Yu, Liqing; Shi, Hang; Xue, Bingzhong

    2016-06-01

    Macrophage inflammation marks all stages of atherogenesis, and AMPK is a regulator of macrophage inflammation. We therefore generated myeloid α1AMPK knockout (MAKO) mice on the LDL receptor knockout (LDLRKO) background to investigate whether myeloid deletion of α1AMPK exacerbates atherosclerosis. When fed an atherogenic diet, MAKO/LDLRKO mice displayed exacerbated atherosclerosis compared with LDLRKO mice. To determine the underlying pathophysiological pathways, we characterized macrophage inflammation/chemotaxis and lipid/cholesterol metabolism in MAKO/LDLRKO mice. Myeloid deletion of α1AMPK increased macrophage inflammatory gene expression and enhanced macrophage migration and adhesion to endothelial cells. Remarkably, MAKO/LDLRKO mice also displayed higher composition of circulating chemotaxically active Ly-6C(high) monocytes, enhanced atherosclerotic plaque chemokine expression, and monocyte recruitment into plaques, leading to increased atherosclerotic plaque macrophage content and inflammation. MAKO/LDLRKO mice also exhibited higher plasma LDL and VLDL cholesterol content, increased circulating apolipoprotein B (apoB) levels, and higher liver apoB expression. We conclude that macrophage α1AMPK deficiency promotes atherogenesis in LDLRKO mice and is associated with enhanced macrophage inflammation and hypercholesterolemia and that macrophage α1AMPK may serve as a therapeutic target for prevention and treatment of atherosclerosis. PMID:26822081

  8. An evolutionary perspective of AMPK-TOR signaling in the three domains of life.

    Roustan, Valentin; Jain, Arpit; Teige, Markus; Ebersberger, Ingo; Weckwerth, Wolfram

    2016-06-01

    AMPK and TOR protein kinases are the major control points of energy signaling in eukaryotic cells and organisms. They form the core of a complex regulatory network to co-ordinate metabolic activities in the cytosol with those in the mitochondria and plastids. Despite its relevance, it is still unclear when and how this regulatory pathway was formed during evolution, and to what extent its representations in the major eukaryotic lineages resemble each other. Here we have traced 153 essential proteins forming the human AMPK-TOR pathways across 412 species representing all three domains of life-prokaryotes (bacteria, archaea) and eukaryotes-and reconstructed their evolutionary history. The resulting phylogenetic profiles indicate the presence of primordial core pathways including seven proto-kinases in the last eukaryotic common ancestor. The evolutionary origins of the oldest components of the AMPK pathway, however, extend into the pre-eukaryotic era, and descendants of these ancient proteins can still be found in contemporary prokaryotes. The TOR complex in turn appears as a eukaryotic invention, possibly to aid in retrograde signaling between the mitochondria and the remainder of the cell. Within the eukaryotes, AMPK/TOR showed both a highly conserved core structure and a considerable plasticity. Most notably, KING1, a protein originally assigned as the γ subunit of AMPK in plants, is more closely related to the yeast SDS23 gene family than to the γ subunits in animals or fungi. This suggests its functional difference from a canonical AMPK γ subunit. PMID:27270999

  9. c-Myc and AMPK Control Cellular Energy Levels by Cooperatively Regulating Mitochondrial Structure and Function.

    Lia R Edmunds

    Full Text Available The c-Myc (Myc oncoprotein and AMP-activated protein kinase (AMPK regulate glycolysis and oxidative phosphorylation (Oxphos although often for different purposes. Because Myc over-expression depletes ATP with the resultant activation of AMPK, we explored the potential co-dependency of and cross-talk between these proteins by comparing the consequences of acute Myc induction in ampk+/+ (WT and ampk-/- (KO murine embryo fibroblasts (MEFs. KO MEFs showed a higher basal rate of glycolysis than WT MEFs and an appropriate increase in response to activation of a Myc-estrogen receptor (MycER fusion protein. However, KO MEFs had a diminished ability to increase Oxphos, mitochondrial mass and reactive oxygen species in response to MycER activation. Other differences between WT and KO MEFs, either in the basal state or following MycER induction, included abnormalities in electron transport chain function, levels of TCA cycle-related oxidoreductases and cytoplasmic and mitochondrial redox states. Transcriptional profiling of pathways pertinent to glycolysis, Oxphos and mitochondrial structure and function also uncovered significant differences between WT and KO MEFs and their response to MycER activation. Finally, an unbiased mass-spectrometry (MS-based survey capable of quantifying ~40% of all mitochondrial proteins, showed about 15% of them to be AMPK- and/or Myc-dependent in their steady state. Significant differences in the activities of the rate-limiting enzymes pyruvate kinase and pyruvate dehydrogenase, which dictate pyruvate and acetyl coenzyme A abundance, were also differentially responsive to Myc and AMPK and could account for some of the differences in basal metabolite levels that were also detected by MS. Thus, Myc and AMPK are highly co-dependent and appear to engage in significant cross-talk across numerous pathways which support metabolic and ATP-generating functions.

  10. LKB1/AMPK inhibits TGF-β1 production and the TGF-β signaling pathway in breast cancer cells.

    Li, Nian-Shuang; Zou, Jun-Rong; Lin, Hui; Ke, Rong; He, Xiao-Ling; Xiao, Lu; Huang, Deqiang; Luo, Lingyu; Lv, Nonghua; Luo, Zhijun

    2016-06-01

    Adenosine monophosphate-activated protein kinase (AMPK) acts as a fuel gauge that maintains energy homeostasis in both normal and cancerous cells, and has emerged as a tumor suppressor. The present study aims to delineate the functional relationship between AMPK and transforming growth factor beta (TGF-β). Our results showed that expression of liver kinase B1 (LKB1), an upstream kinase of AMPK, impeded TGF-β-induced Smad phosphorylation and their transcriptional activity in breast cancer cells, whereas knockdown of LKB1 or AMPKα1 subunit by short hairpin RNA (shRNA) enhanced the effect of TGF-β. Furthermore, AMPK activation reduced the promoter activity of TGF-β1. In accordance, type 2 diabetic patients taking metformin displayed a trend of reduction of serum TGF-β1, as compared with those without metformin. A significant reduction of serum TGF-β1 was found in mice after treatment with metformin. These results suggest that AMPK inhibits the transcription of TGF-β1, leading to reduction of its concentration in serum. Finally, metformin suppressed epithelial-to-mesenchymal transition of mammary epithelial cells. Taken together, our study demonstrates that AMPK exerts multiple actions on TGF-β signaling and supports that AMPK can serve as a therapeutic drug target for breast cancer. PMID:26718214

  11. Two weeks of metformin treatment enhances mitochondrial respiration in skeletal muscle of AMPK kinase dead but not wild type mice.

    Jonas M Kristensen

    Full Text Available Metformin is used as an anti-diabetic drug. Metformin ameliorates insulin resistance by improving insulin sensitivity in liver and skeletal muscle. Reduced mitochondrial content has been reported in type 2 diabetic muscles and it may contribute to decreased insulin sensitivity characteristic for diabetic muscles. The molecular mechanism behind the effect of metformin is not fully clarified but inhibition of complex I in the mitochondria and also activation of the 5'AMP activated protein kinase (AMPK has been reported in muscle. Furthermore, both AMPK activation and metformin treatment have been associated with stimulation of mitochondrial function and biogenesis. However, a causal relationship in skeletal muscle has not been investigated. We hypothesized that potential effects of in vivo metformin treatment on mitochondrial function and protein expressions in skeletal muscle are dependent upon AMPK signaling. We investigated this by two weeks of oral metformin treatment of muscle specific kinase dead α(2 (KD AMPK mice and wild type (WT littermates. We measured mitochondrial respiration and protein activity and expressions of key enzymes involved in mitochondrial carbohydrate and fat metabolism and oxidative phosphorylation. Mitochondrial respiration, HAD and CS activity, PDH and complex I-V and cytochrome c protein expression were all reduced in AMPK KD compared to WT tibialis anterior muscles. Surprisingly, metformin treatment only enhanced respiration in AMPK KD mice and thereby rescued the respiration defect compared to the WT mice. Metformin did not influence protein activities or expressions in either WT or AMPK KD mice.We conclude that two weeks of in vivo metformin treatment enhances mitochondrial respiration in the mitochondrial deficient AMPK KD but not WT mice. The improvement seems to be unrelated to AMPK, and does not involve changes in key mitochondrial proteins.

  12. Central acylated ghrelin improves memory function and hippocampal AMPK activation and partly reverses the impairment of energy and glucose metabolism in rats infused with β-amyloid.

    Kang, Suna; Moon, Na Rang; Kim, Da Sol; Kim, Sung Hoon; Park, Sunmin

    2015-09-01

    Ghrelin is a gastric hormone released during the fasting state that targets the hypothalamus where it induces hunger; however, emerging evidence suggests it may also affect memory function. We examined the effect of central acylated-ghrelin and DES-acetylated ghrelin (native ghrelin) on memory function and glucose metabolism in an experimentally induced Alzheimer's disease (AD) rat model. AD rats were divided into 3 groups and Non-AD rats were used as a normal-control group. Each rat in the AD groups had intracerebroventricular (ICV) infusion of β-amyloid (25-35; 16.8nmol/day) into the lateral ventricle for 3 days, and then the pumps were changed to infuse either acylated-ghrelin (0.2nmol/h; AD-G), DES-acylated ghrelin (0.2nmol/h; AD-DES-G), or saline (control; AD-C) for 3 weeks. The Non-AD group had ICV infusion of β-amyloid (35-25) which does not deposit in the hippocampus. During the next 3 weeks memory function, food intake, body weight gain, body fat composition, and glucose metabolism were measured. AD-C exhibited greater β-amyloid deposition compared to Non-AD-C, and AD-G suppressed the increased β-amyloid deposition and potentiated the phosphorylation AMPK. In addition, AD-G increased the phosphorylation GSK and decreased the phosphorylation of Tau in comparison to AD-C and AD-DES-G. Cognitive function, measured by passive avoidance and water maze tests, was much lower in AD-C than Non-AD-C whereas AD-G but not AD-DES-G prevented the decrease (pintermittent fasting to facilitate sustained elevations of acyl-ghrelin should be investigated for cognitive and metabolic benefits, especially in person with early symptoms of memory impairment. PMID:26188171

  13. Targeting AMPK signalling pathway with natural medicines for atherosclerosis therapy: an integration of in silico screening and in vitro assay.

    Ou, Tiantong; Hou, Xumin; Guan, Shaofeng; Dai, Jinjie; Han, Wenzheng; Li, Ruogu; Wang, Wenxia; Qu, Xinkai; Zhang, Min

    2016-06-01

    An integration of virtual screening and kinase assay was reported to identify AMPK kinase inhibitors from various natural medicines.The activation of AMP-activated protein kinase (AMPK) signalling pathway plays a central role in the pathologic progression of atherosclerosis (AS). Targeting the AMPK is thus considered as a potential therapeutics to attenuate AS. Here, we report the establishment of a synthetic pipeline that integrates in silico virtual screening and in vitro kinase assay to discover new lead compounds of AMPK inhibitors. The screening is performed against a large-size pool of structurally diverse natural products, from which a number of compounds are inferred as promising candidates, and few of them are further tested in vitro by using a standard kinase assay protocol to determine their inhibitory potency against AMPK. With this scheme we successfully identify five potent AMPK inhibitors with IC50 values at micromolar level. We also examine the structural basis and molecular mechanism of nonbonded interaction network across the modelled complex interface of AMPK kinase domain with a newly identified natural medicine. PMID:26166578

  14. AMPK-independent inhibition of human macrophage ER stress response by AICAR.

    Boß, Marcel; Newbatt, Yvette; Gupta, Sahil; Collins, Ian; Brüne, Bernhard; Namgaladze, Dmitry

    2016-01-01

    Obesity-associated insulin resistance is driven by inflammatory processes in response to metabolic overload. Obesity-associated inflammation can be recapitulated in cell culture by exposing macrophages to saturated fatty acids (SFA), and endoplasmic reticulum (ER) stress responses essentially contribute to pro-inflammatory signalling. AMP-activated protein kinase (AMPK) is a central metabolic regulator with established anti-inflammatory actions. Whether pharmacological AMPK activation suppresses SFA-induced inflammation in a human system is unclear. In a setting of hypoxia-potentiated inflammation induced by SFA palmitate, we found that the AMP-mimetic AMPK activator 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) potently suppressed upregulation of ER stress marker mRNAs and pro-inflammatory cytokines. Furthermore, AICAR inhibited macrophage ER stress responses triggered by ER-stressors thapsigargin or tunicamycin. Surprisingly, AICAR acted independent of AMPK or AICAR conversion to 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranosyl monophosphate (ZMP) while requiring intracellular uptake via the equilibrative nucleoside transporter (ENT) ENT1 or the concentrative nucleoside transporter (CNT) CNT3. AICAR did not affect the initiation of the ER stress response, but inhibited the expression of major ER stress transcriptional effectors. Furthermore, AICAR inhibited autophosphorylation of the ER stress sensor inositol-requiring enzyme 1α (IRE1α), while activating its endoribonuclease activity in vitro. Our results suggest that AMPK-independent inhibition of ER stress responses contributes to anti-inflammatory and anti-diabetic effects of AICAR. PMID:27562249

  15. Dihydromyricetin improves skeletal muscle insulin resistance by inducing autophagy via the AMPK signaling pathway.

    Shi, Linying; Zhang, Ting; Liang, Xinyu; Hu, Qin; Huang, Juan; Zhou, Yong; Chen, Mingliang; Zhang, Qianyong; Zhu, Jundong; Mi, Mantian

    2015-07-01

    Skeletal muscle insulin resistance (SMIR) plays an important role in the pathogenesis of type 2 diabetes. Dihydromyricetin (DHM), a natural flavonoid, exerts various bioactivities including anti-oxidative and hepatoprotective effects. Herein, we intended to determine the effect of DHM on SMIR and the underlying mechanisms. We found that DHM increased the expression of phosphorylated insulin receptor substrate-1, phosphorylated Akt and glucose uptake capacity in palmitate-treated L6 myotubes under insulin-stimulated conditions. The expression of light chain 3, Beclin 1, autophagy-related gene 5 (Atg5), the degradation of sequestosome 1 and the formation of autophagosomes were also upregulated by DHM. Suppression of autophagy by 3-methyladenine and bafilomycin A1 or Atg5 and Beclin1 siRNA abolished the favorable effects of DHM on SMIR. Furthermore, DHM increased the levels of phosphorylated AMP-activated protein kinase (AMPK) and Ulk1, and decreased phosphorylated mTOR levels. AMPK inhibitor compound C (CC) and AMPK siRNA abrogated DHM-induced autophagy, subsequently suppressed DHM-induced SMIR improvement. Additionally, DHM inhibited the activity of F1F0-ATPase thereby activating AMPK. Finally, the results of in vivo study conducted in high fat diet-fed rats were consistent with the findings of in vitro study. In conclusion, DHM improved SMIR by inducing autophagy via the activation of AMPK signaling pathway. PMID:25797177

  16. Metformin interferes with bile acid homeostasis through AMPK-FXR crosstalk.

    Lien, Fleur; Berthier, Alexandre; Bouchaert, Emmanuel; Gheeraert, Céline; Alexandre, Jeremy; Porez, Geoffrey; Prawitt, Janne; Dehondt, Hélène; Ploton, Maheul; Colin, Sophie; Lucas, Anthony; Patrice, Alexandre; Pattou, François; Diemer, Hélène; Van Dorsselaer, Alain; Rachez, Christophe; Kamilic, Jelena; Groen, Albert K; Staels, Bart; Lefebvre, Philippe

    2014-03-01

    The nuclear bile acid receptor farnesoid X receptor (FXR) is an important transcriptional regulator of bile acid, lipid, and glucose metabolism. FXR is highly expressed in the liver and intestine and controls the synthesis and enterohepatic circulation of bile acids. However, little is known about FXR-associated proteins that contribute to metabolic regulation. Here, we performed a mass spectrometry-based search for FXR-interacting proteins in human hepatoma cells and identified AMPK as a coregulator of FXR. FXR interacted with the nutrient-sensitive kinase AMPK in the cytoplasm of target cells and was phosphorylated in its hinge domain. In cultured human and murine hepatocytes and enterocytes, pharmacological activation of AMPK inhibited FXR transcriptional activity and prevented FXR coactivator recruitment to promoters of FXR-regulated genes. Furthermore, treatment with AMPK activators, including the antidiabetic biguanide metformin, inhibited FXR agonist induction of FXR target genes in mouse liver and intestine. In a mouse model of intrahepatic cholestasis, metformin treatment induced FXR phosphorylation, perturbed bile acid homeostasis, and worsened liver injury. Together, our data indicate that AMPK directly phosphorylates and regulates FXR transcriptional activity to precipitate liver injury under conditions favoring cholestasis. PMID:24531544

  17. AMPK Agonist AICAR Improves Cognition and Motor Coordination in Young and Aged Mice

    Kobilo, Tali; Guerrieri, Davide; Zhang, Yongqing; Collica, Sarah C.; Becker, Kevin G.; van Praag, Henriette

    2014-01-01

    Normal aging can result in a decline of memory and muscle function. Exercise may prevent or delay these changes. However, aging-associated frailty can preclude physical activity. In young sedentary animals, pharmacological activation of AMP-activated protein kinase (AMPK), a transcriptional regulator important for muscle physiology, enhanced…

  18. Prior AICAR stimulation increases insulin sensitivity in mouse skeletal muscle in an AMPK-dependent manner

    Kjøbsted, Rasmus; Treebak, Jonas Thue; Fentz, Joachim;

    2015-01-01

    Acute exercise increases glucose uptake in skeletal muscle by an insulin-independent mechanism. In the period after exercise insulin sensitivity to increase glucose uptake is enhanced. The molecular mechanisms underpinning this phenomenon are poorly understood, but appear to involve an increased...... AMPK activation increases skeletal muscle insulin sensitivity. We found that prior AICAR stimulation of wild-type mouse muscle increases insulin sensitivity to stimulate glucose uptake. However, this was not observed in mice with reduced or ablated AMPK activity in skeletal muscle. Furthermore, prior...... AICAR stimulation enhanced insulin-stimulated phosphorylation of TBC1D4 at Thr(649) and Ser(711) in wild-type muscle only. These phosphorylation events were positively correlated with glucose uptake. Our results provide evidence to support that AMPK is sufficient to increase skeletal muscle insulin...

  19. AMPK regulates circadian rhythms in a tissue- and isoform-specific manner.

    Jee-Hyun Um

    Full Text Available BACKGROUND: AMP protein kinase (AMPK plays an important role in food intake and energy metabolism, which are synchronized to the light-dark cycle. In vitro, AMPK affects the circadian rhythm by regulating at least two clock components, CKIα and CRY1, via direct phosphorylation. However, it is not known whether the catalytic activity of AMPK actually regulates circadian rhythm in vivo. METHODOLOGY/PRINCIPAL FINDING: THE CATALYTIC SUBUNIT OF AMPK HAS TWO ISOFORMS: α1 and α2. We investigate the circadian rhythm of behavior, physiology and gene expression in AMPKα1-/- and AMPKα2-/- mice. We found that both α1-/- and α2-/- mice are able to maintain a circadian rhythm of activity in dark-dark (DD cycle, but α1-/- mice have a shorter circadian period whereas α2-/- mice showed a tendency toward a slightly longer circadian period. Furthermore, the circadian rhythm of body temperature was dampened in α1-/- mice, but not in α2-/- mice. The circadian pattern of core clock gene expression was severely disrupted in fat in α1-/- mice, but it was severely disrupted in the heart and skeletal muscle of α2-/- mice. Interestingly, other genes that showed circadian pattern of expression were dysreguated in both α1-/- and α2-/- mice. The circadian rhythm of nicotinamide phosphoryl-transferase (NAMPT activity, which converts nicotinamide (NAM to NAD+, is an important regulator of the circadian clock. We found that the NAMPT rhythm was absent in AMPK-deficient tissues and cells. CONCLUSION/SIGNIFICANCE: This study demonstrates that the catalytic activity of AMPK regulates circadian rhythm of behavior, energy metabolism and gene expression in isoform- and tissue-specific manners.

  20. AMPK and the biochemistry of exercise: implications for human health and disease

    Richter, Erik; Ruderman, Neil B.

    2009-01-01

    AMPK (AMP-activated protein kinase) is a phylogenetically conserved fuel-sensing enzyme that is present in all mammalian cells. During exercise, it is activated in skeletal muscle in humans, and at least in rodents, also in adipose tissue, liver and perhaps other organs by events that increase th...

  1. Molecular mechanisms of appetite and obesity: a role for brain AMPK.

    Martínez de Morentin, Pablo B; Urisarri, Adela; Couce, María L; López, Miguel

    2016-10-01

    Feeding behaviour and energy storage are both crucial aspects of survival. Thus, it is of fundamental importance to understand the molecular mechanisms regulating these basic processes. The AMP-activated protein kinase (AMPK) has been revealed as one of the key molecules modulating energy homoeostasis. Indeed, AMPK appears to be essential for translating nutritional and energy requirements into generation of an adequate neuronal response, particularly in two areas of the brain, the hypothalamus and the hindbrain. Failure of this physiological response can lead to energy imbalance, ultimately with extreme consequences, such as leanness or obesity. Here, we will review the data that put brain AMPK in the spotlight as a regulator of appetite. PMID:27555613

  2. Age-related changes in AMP-activated protein kinase after stroke

    Liu, Fudong; Benashski, Sharon E; Persky, Rebecca; Xu, Yan; Li, Jun; McCullough, Louise D.

    2011-01-01

    Adenosine monophosphate-activated protein kinase (AMPK) is an evolutionary conserved energy sensor sensitive to changes in cellular AMP/ATP ratio which is activated by phosphorylation (pAMPK). pAMPK levels decrease in peripheral tissues with age, but whether this also occurs in the aged brain, and how this contributes to the ability of the aged brain to cope with ischemic stress is unknown. This study investigated the activation of AMPK and the response to AMPK inhibition after induced stroke...

  3. Irisin improves endothelial function in obese mice through the AMPK-eNOS pathway.

    Han, Fang; Zhang, Shuxian; Hou, Ningning; Wang, Di; Sun, Xiaodong

    2015-11-01

    Irisin is a novel hormone secreted by myocytes. Lower levels of irisin are independently associated with endothelial dysfunction in obese subjects. The objective of this study was to explore whether irisin exerts a direct vascular protective effect on endothelial function in high-fat-diet-induced obese mice. Male C57BL/6 mice were given chow or a high-fat diet with or without treatment with irisin. Aortic endothelial function was determined by measuring endothelium-dependent vasodilatation (EDV). Nitric oxide (NO) in the aorta was determined. The effect of irisin on the levels of AMP-activated protein kinase (AMPK), Akt, and endothelial NO synthase (eNOS) phosphorylation in endothelial cells was determined. Human umbilical vein endothelial cells were used to study the role of irisin in the AMPK-eNOS pathway. Acetylcholine-stimulated EDV was significantly lower in obese mice compared with control mice. Treatment of obese mice with irisin significantly enhanced EDV and improved endothelial function. This beneficial effect of irisin was partly attenuated in the presence of inhibitors of AMPK, Akt, and eNOS. Treatment of obese mice with irisin enhanced NO production and phosphorylation of AMPK, Akt, and eNOS in endothelial cells. These factors were also enhanced by irisin in human umbilical vein endothelial cells in vitro. Suppression of AMPK expression by small interfering RNA blocked irisin-induced eNOS and Akt phosphorylation and NO production. We have provided the first evidence that irisin improves endothelial function in aortas of high-fat-diet-induced obese mice. The mechanism for this protective effect is related to the activation of the AMPK-eNOS signaling pathway. PMID:26371167

  4. Ginkgolide C Suppresses Adipogenesis in 3T3-L1 Adipocytes via the AMPK Signaling Pathway

    Chian-Jiun Liou

    2015-01-01

    Full Text Available Ginkgolide C, isolated from Ginkgo biloba leaves, is a flavone reported to have multiple biological functions, from decreased platelet aggregation to ameliorating Alzheimer disease. The study aim was to evaluate the antiadipogenic effect of ginkgolide C in 3T3-L1 adipocytes. Ginkgolide C was used to treat differentiated 3T3-L1 cells. Cell supernatant was collected to assay glycerol release, and cells were lysed to measure protein and gene expression related to adipogenesis and lipolysis by western blot and real-time PCR, respectively. Ginkgolide C significantly suppressed lipid accumulation in differentiated adipocytes. It also decreased adipogenesis-related transcription factor expression, including peroxisome proliferator-activated receptor and CCAAT/enhancer-binding protein. Furthermore, ginkgolide C enhanced adipose triglyceride lipase and hormone-sensitive lipase production for lipolysis and increased phosphorylation of AMP-activated protein kinase (AMPK, resulting in decreased activity of acetyl-CoA carboxylase for fatty acid synthesis. In coculture with an AMPK inhibitor (compound C, ginkgolide C also improved activation of sirtuin 1 and phosphorylation of AMPK in differentiated 3T3-L1 cells. The results suggest that ginkgolide C is an effective flavone for increasing lipolysis and inhibiting adipogenesis in adipocytes through the activated AMPK pathway.

  5. The impact of endurance exercise on global and AMPK gene-specific DNA methylation.

    King-Himmelreich, Tanya S; Schramm, Stefanie; Wolters, Miriam C; Schmetzer, Julia; Möser, Christine V; Knothe, Claudia; Resch, Eduard; Peil, Johannes; Geisslinger, Gerd; Niederberger, Ellen

    2016-05-27

    Alterations in gene expression as a consequence of physical exercise are frequently described. The mechanism of these regulations might depend on epigenetic changes in global or gene-specific DNA methylation levels. The AMP-activated protein kinase (AMPK) plays a key role in maintenance of energy homeostasis and is activated by increases in the AMP/ATP ratio as occurring in skeletal muscles after sporting activity. To analyze whether exercise has an impact on the methylation status of the AMPK promoter, we determined the AMPK methylation status in human blood samples from patients before and after sporting activity in the context of rehabilitation as well as in skeletal muscles of trained and untrained mice. Further, we examined long interspersed nuclear element 1 (LINE-1) as indicator of global DNA methylation changes. Our results revealed that light sporting activity in mice and humans does not alter global DNA methylation but has an effect on methylation of specific CpG sites in the AMPKα2 gene. These regulations were associated with a reduced AMPKα2 mRNA and protein expression in muscle tissue, pointing at a contribution of the methylation status to AMPK expression. Taken together, these results suggest that exercise influences AMPKα2 gene methylation in human blood and eminently in the skeletal muscle of mice and therefore might repress AMPKα2 gene expression. PMID:27103439

  6. Effects of wintertime fasting and seasonal adaptation on AMPK and ACC in hypothalamus, adipose tissue and liver of the raccoon dog (Nyctereutes procyonoides).

    Kinnunen, Sanni; Mänttäri, Satu; Herzig, Karl-Heinz; Nieminen, Petteri; Mustonen, Anne-Mari; Saarela, Seppo

    2016-02-01

    The raccoon dog (Nyctereutes procyonoides) is a canid with autumnal fattening and passive wintering strategy. We examined the effects of wintertime fasting and seasonality on AMP-activated protein kinase (AMPK), a regulator of metabolism, and its target, acetyl-CoA carboxylase (ACC) on the species. Twelve farmed raccoon dogs (eleven females/one male) were divided into two groups: half were fasted for ten weeks in December-March (winter fasted) and the others were fed ad libitum (winter fed). A third group (autumn fed, eight females) was fed ad libitum and sampled in December. Total AMPK, ACC and their phosphorylated forms (pAMPK, pACC) were measured from hypothalamus, liver, intra-abdominal (iWAT) and subcutaneous white adipose tissues (sWAT). The fasted animals lost 32% and the fed 20% of their body mass. Hypothalamic AMPK expression was lower and pACC levels higher in the winter groups compared to the autumn fed group. Liver pAMPK was lower in the winter fasted group, with consistently decreased ACC and pACC. AMPK and pAMPK were down-regulated in sWAT and iWAT of both winter groups, with a parallel decline in pACC in sWAT. The responses of AMPK and ACC to fasting were dissimilar to the effects observed previously in non-seasonal mammals and hibernators. Differences between the winter fed and autumn fed groups indicate that the functions of AMPK and ACC could be regulated in a season-dependent manner. Furthermore, the distinctive effects of prolonged fasting and seasonal adaptation on AMPK-ACC pathway could contribute to the wintering strategy of the raccoon dog. PMID:26603554

  7. Type 2 diabetes is associated with altered NF-¿B DNA binding activity, JNK phosphorylation, and AMPK phosphorylation in skeletal muscle after LPS

    Andreasen, Anne Sofie; Kelly, Meghan; Berg, Ronan Martin Griffin;

    2011-01-01

    Systemic inflammation is often associated with impaired glucose metabolism. We therefore studied the activation of inflammatory pathway intermediates that interfere with glucose uptake during systemic inflammation by applying a standardised inflammatory stimulus in vivo. After ethical approval, i...

  8. Post-Meal Responses of Elongation Factor 2 (eEF2 and Adenosine Monophosphate-Activated Protein Kinase (AMPK to Leucine and Carbohydrate Supplements for Regulating Protein Synthesis Duration and Energy Homeostasis in Rat Skeletal Muscle

    Donald K. Layman

    2012-11-01

    Full Text Available Previous research demonstrates that the anabolic response of muscle protein synthesis (MPS to a meal is regulated at the level of translation initiation with signals derived from leucine (Leu and insulin to activate mTORC1 signaling. Recent evidence suggests that the duration of the meal response is limited by energy status of the cell and inhibition of translation elongation factor 2 (eEF2. This study evaluates the potential to extend the anabolic meal response with post-meal supplements of Leu or carbohydrates. Adult (~256 g male Sprague-Dawley rats were food deprived for 12 h, then either euthanized before a standard meal (time 0 or at 90 or 180 min post-meal. At 135 min post-meal, rats received one of five oral supplements: 270 mg leucine (Leu270, 80:40:40 mg leucine, isoleucine, and valine (Leu80, 2.63 g carbohydrates (CHO2.6, 1 g carbohydrates (CHO1.0, or water (Sham control. Following the standard meal, MPS increased at 90 min then declined to pre-meal baseline at 180 min. Rats administered Leu270, Leu80, CHO2.6, or CHO1.0 maintained elevated rates of MPS at 180 min, while Sham controls declined from peak values. Leu80 and CHO1.0 treatments maintained MPS, but with values intermediate between Sham controls and Leu270 and CHO2.6 supplements. Consistent with MPS findings, the supplements maintained elongation activity and cellular energy status by preventing increases in AMP/ATP and phosphorylation of adenosine monophosphate-activated protein kinase (AMPK, acetyl-CoA carboxylase ACC and eEF2. The impact of the supplements on MPS and cellular energy status was in proportion to the energy content within the individual treatments (i.e., Leu270 > Leu80; CHO2.6 > CHO1.0, but the Leu supplements produced a disproportionate anabolic stimulation of MPS, eEF2 and energy status with significantly lower energy content. In summary, the incongruity between MPS and translation initiation at 180 min reflects a block in translation elongation due to

  9. Resveratrol Inhibition of Rac1-Derived Reactive Oxygen Species by AMPK Decreases Blood Pressure in a Fructose-Induced Rat Model of Hypertension

    Cheng, Pei-Wen; Lee, Hui-Chieh; Lu, Pei-Jung; Chen, Hsin-Hung; Lai, Chi-Cheng; Sun, Gwo-Ching; Yeh, Tung-Chen; Hsiao, Michael; Lin, Yu-Te; Liu, Chun-Peng; Tseng, Ching-Jiunn

    2016-01-01

    Recent studies have reported that the activation of AMP-activated protein kinase (AMPK) suppressed oxidative stress. The aim of this study was to examine whether the activation of AMPK in the brain decreased Rac1-induced ROS generation, thereby reducing blood pressure (BP) in rats with fructose-induced hypertension. The inhibition of ROS by treatment with an AMPK activator (oral resveratrol, 10 mg/kg/day) for 1 week decreased the BP and increased the NO production in the rostral ventrolateral medulla (RVLM) of fructose-fed rats but not in control Wistar-Kyoto (WKY) rats. In addition, resveratrol treatment abolished the Rac1-induced increases in the activity of the NADPH oxidase subunits p22-phox and reduced the activity of SOD2, while treatment with an AMPK inhibitor (compound C, 40 μM/day) had the opposite effect, in the fructose-fed rats. Interestingly, the activation of AMPK abolished Rac1 activation and decreased BP by inducing the activities of extracellular signal-regulated kinases 1 and 2 (ERK1/2) and ribosomal protein S6 kinase (RSK) and nNOS phosphorylation in the fructose-fed rats. We conclude that the activation of AMPK decreased BP, abolished ROS generation, and enhanced ERK1/2-RSK-nNOS pathway activity by negatively regulating Racl-induced NADPH oxidase levels in the RVLM during oxidative stress–associated hypertension. PMID:27138844

  10. The glycolytic shift in fumarate-hydratase-deficient kidney cancer lowers AMPK levels, increases anabolic propensities and lowers cellular iron levels

    Tong, Winghang

    2011-09-01

    Inactivation of the TCA cycle enzyme, fumarate hydratase (FH), drives a metabolic shift to aerobic glycolysis in FH-deficient kidney tumors and cell lines from patients with hereditary leiomyomatosis renal cell cancer (HLRCC), resulting in decreased levels of AMP-activated kinase (AMPK) and p53 tumor suppressor, and activation of the anabolic factors, acetyl-CoA carboxylase and ribosomal protein S6. Reduced AMPK levels lead to diminished expression of the DMT1 iron transporter, and the resulting cytosolic iron deficiency activates the iron regulatory proteins, IRP1 and IRP2, and increases expression of the hypoxia inducible factor HIF-1α, but not HIF-2α. Silencing of HIF-1α or activation of AMPK diminishes invasive activities, indicating that alterations of HIF-1α and AMPK contribute to the oncogenic growth of FH-deficient cells. © 2011 Elsevier Inc.

  11. Cyanidin and malvidin in aqueous extracts of black carrots fermented with Aspergillus oryzae prevent the impairment of energy, lipid and glucose metabolism in estrogen-deficient rats by AMPK activation.

    Park, Sunmin; Kang, Suna; Jeong, Do-Youn; Jeong, Seong-Yeop; Park, Jae Jung; Yun, Ho Sik

    2015-03-01

    decreasing FAS and SREBP-1c expression in comparison with cyanidin-3-rutinoside and malvidin-3,5-diglycosides. In conclusion, with increasing cyanidin and malvidin, BCAO prevented the exacerbation of lipid and glucose metabolism by activating hepatic insulin signaling and AMPK activation by in OVX rats. PMID:25701199

  12. APS improves free fatty acid metabolism by activating AMPK and promoting translocation of FAT/CD36 in C2C12 myoblasts%黄芪多糖通过活化AMPK和促进骨骼肌FAT/CD36转位改善成肌细胞FFAs代谢

    胡阳黔; 李静; 刘坚; 欧阳静萍; 宋杰

    2013-01-01

    AIM: To investigate the effect of Astragalus polysaccharides (APS) on the metabolism of free fatty acids (FFAs) in C2C12 myoblasts. METHODS: Cultured C2C12 myoblasts were used in the study. The viability of C2C12 myoblasts treated with FFAs at different concentrations for different time was observed by MTT assay. The concentrations of FFAs in the medium were detected by acetyl-CoA synthase (ACS) -acetyl-CoA oxidase (ACOD) method. The expression of fatty acid translocase (FAT/CD36), AMPK and p-AMPK protein was examined by Western blotting. RESULTS; FFAs decreased the viability of C2C12 myoblasts in a time- and concentration-dependent manner. Compared with FFAs group, the expression of cellular membrane FAT/CD36 and p-AMPK proteins increased in FFAs + APS group, but total AMPK and FAT/CD36 protein expression was not significantly changed. Meanwhile, the concentration of FFAs in the medium decreased and the cell viability increased in FFAs + APS group as compared with the group. CONCLUSION: APS improves the metabolism of FFAs by activating AMPK and promoting translocation of FAT/CD36 in C2C12 myoblasts.%目的:探讨黄芪多糖(Astragalus polysaccharides,APS)对骨骼肌游离脂肪酸(free fatty acids,FFAs)代谢的影响及其机制.方法:培养小鼠C2C12成肌细胞;MTT法检测不同浓度FFAs作用不同时间对细胞活性的影响.根据MTT结果选取FFAs最适浓度和时间处理细胞并用APS干预,采用乙酰辅酶A合成酶-乙酰辅酶A氧化酶法检测APS干预前后培养液FFAs浓度;Western blotting测APS干预前后细胞膜脂肪酸转位酶(FAT/CD36)、总FAT/CD36、磷酸化腺苷酸活化蛋白激酶(phosphorylated AMP-activated protein kinase,p-AMPK)和总AMPK蛋白表达.结果:FFAs对细胞的毒性呈浓度和时间依赖性.与FFAs组比较,FFAs+ APS组细胞膜FAT/CD36及p-AMPK蛋白表达增加(P<0.05),而总FAT/CD36及总AMPK蛋白表达无明显差异(P>0.05),同时培养液FFAs浓度降低,细胞活性增加(P<0.05).

  13. Contraction-stimulated glucose transport in muscle is controlled by AMPK and mechanical stress but not sarcoplasmatic reticulum Ca2+ release

    Jensen, Thomas Elbenhardt; Sylow, Lykke; Rose, Adam John; Madsen, Agnete Louise Bjerregaard; Angin, Yeliz; Maarbjerg, Stine J; Richter, Erik

    2014-01-01

    signals through proteins such as AMPK. Here, we demonstrate in incubated mouse muscle that Ca(2+) release is neither sufficient nor strictly necessary to increase glucose transport. Rather, the glucose transport response is associated with metabolic feedback signals through AMPK, and mechanical stress......-activated signals. Furthermore, artificial stimulation of AMPK combined with passive stretch of muscle is additive and sufficient to elicit the full contraction glucose transport response. These results suggest that ATP-turnover and mechanical stress feedback are sufficient to fully increase glucose transport...

  14. The Effects of Altitude Training on the AMPK-Related Glucose Transport Pathway in the Red Skeletal Muscle of Both Lean and Obese Zucker Rats

    Chen, Yu-Ching; Lee, Shin-Da; Kuo, Cha-Hua; Ho, Low-Tone

    2011-01-01

    Chen, Yu-Ching, Shin-Da Lee, Cha-Hua Kuo, and Low-Tone Ho. The effects of altitude training on the AMPK-related glucose transport pathway in the red skeletal muscle of both lean and obese Zucker rats. High Alt. Med. Biol. 12:371–378.—Introduction: The skeletal muscle AMP-activated protein kinase (AMPK)-related glucose transport pathway is involved in glucose homeostasis. Aim: In this study, we examined whether obese control Zucker rats had abnormal expression of proteins in the LKB1-AMPK-AS16...

  15. Glucose-Based Regulation of miR-451/AMPK Signaling Depends on the OCT1 Transcription Factor

    Khairul I. Ansari

    2015-05-01

    Full Text Available In aggressive, rapidly growing solid tumors such as glioblastoma multiforme (GBM, cancer cells face frequent dynamic changes in their microenvironment, including the availability of glucose and other nutrients. These challenges require that tumor cells have the ability to adapt in order to survive periods of nutrient/energy starvation. We have identified a reciprocal negative feedback loop mechanism in which the levels of microRNA-451 (miR-451 are negatively regulated through the phosphorylation and inactivation of its direct transcriptional activator OCT1 by 5′ AMP-activated protein kinase (AMPK, which is activated by glucose depletion-induced metabolic stress. Conversely, in a glucose-rich environment, unrestrained expression of miR-451 suppresses AMPK pathway activity. These findings uncover miR-451 as a major effector of glucose-regulated AMPK signaling, allowing tumor cell adaptation to variations in nutrient availability in the tumor microenvironment.

  16. Molecular signalling pathways involved in AMPK-mediated neuronal preconditioning and optimisation of a high content screening assay to monitor excitotoxic neuronal death.

    Kumar, Ujval A

    2013-01-01

    Neuronal preconditioning is a phenomenon where a previous exposure to a sublethal stress stimulus increases the resistance of neurons towards a second, normally lethal stress stimulus. Activation of the energy stress sensor, AMP-activated protein kinase (AMPK) has been shown to contribute to the protective effects of ischemic and mitochondrial uncoupling-induced preconditioning in neurons, however the molecular basis of AMPK-mediated preconditioning have been less well characterised. First...

  17. Stimulation of Wnt/β-Catenin Signaling to Improve Bone Development by Naringin via Interacting with AMPK and Akt

    Dawei Wang

    2015-07-01

    Full Text Available Background/Aims: Naringin is a naturally existing compound in citrus fruits and has been elucidated to promote bone development and maintenance. Methods: The biological roles of naringin were investigated in vitro using osteoblast-like UMR-106 cells, and in vivo through performing ovariectomy to mimic osteoporosis in female mice. Since Wnt/β-catenin signaling is involved in osteoblastogenesis, the effect of naringin on Wnt/β-catenin signaling was studied. Results: Naringin promoted the mRNA and protein expressions of β-catenin, and improved Ser552 phosphorylation on β-catenin in UMR-106 cells, which leads to the activation of lymphoid enhancer factor (LEF/ T-cell factor (TCF transcription factors. The recruitments of protein kinase B (Akt inhibitor (Akti-1/2 and AMP-activated protein kinase (AMPK inhibitor (Dorsomorphin reduced the influence of naringin on β-catenin phosphorylation, suggesting naringin activates β-catenin via regulating Akt and AMPK. In ovariectomized (OVX mice naringin treatment improved the bone strength while AMPK and Akt inhibitors partly reversed the effect, which further proved the involvements of Akt and AMPK in the action of naringin in vivo. Conclusion: Our study points to a novel finding on the mechanism of naringin in facilitating bone formation via Akt and AMPK signaling.

  18. Two weeks of metformin treatment enhances mitochondrial respiration in skeletal muscle of AMPK kinase dead but not wild type mice

    Kristensen, Jonas Møller; Larsen, Steen; Helge, Jørn Wulff;

    2013-01-01

    diabetic muscles. The molecular mechanism behind the effect of metformin is not fully clarified but inhibition of complex I in the mitochondria and also activation of the 5'AMP activated protein kinase (AMPK) has been reported in muscle. Furthermore, both AMPK activation and metformin treatment have been......Metformin is used as an anti-diabetic drug. Metformin ameliorates insulin resistance by improving insulin sensitivity in liver and skeletal muscle. Reduced mitochondrial content has been reported in type 2 diabetic muscles and it may contribute to decreased insulin sensitivity characteristic for...

  19. Effect of birth weight and 12 weeks of exercise training on exercise-induced AMPK signaling in human skeletal muscle

    Mortensen, Brynjulf; Hingst, Janne Rasmuss; Frederiksen, Nicklas;

    2013-01-01

    Subjects with a low birth weight (LBW) display increased risk of developing type 2 diabetes (T2D). We hypothesized that this is associated with defects in muscle adaptations following acute and regular physical activity, evident by impairments in the exercise-induced activation of AMPK signaling....... We investigated 21 LBW and 21 normal birth weight (NBW) subjects during 1 hour of acute exercise performed at the same relative workload before and after 12 weeks of exercise training. Multiple skeletal muscle biopsies were obtained before and after exercise. Protein levels and phosphorylation status...... need for AMPK to control energy turnover during exercise. Thus, the remaining ¿3-associated AMPK activation by acute exercise after exercise training might be sufficient to maintain cellular energy balance....

  20. Hypothalamic AMPK and fatty acid metabolism mediate thyroid regulation of energy balance

    López, Miguel; Varela, Luis; Vázquez, María J.; Rodríguez-Cuenca, Sergio; González, Carmen R.; Velagapudi, Vidya R.; Morgan, Donald A.; Schoenmakers, Erik; Agassandian, Khristofor; Lage, Ricardo; de Morentin, Pablo Blanco Martínez; Tovar, Sulay; Nogueiras, Rubén; Carling, David; Lelliott, Christopher

    2010-01-01

    Thyroid hormones have widespread cellular effects; however it is unclear whether their effects on the central nervous system (CNS) contribute to global energy balance. Here, we demonstrate that either whole body hyperthyroidism or central administration of triiodothyronine (T3) decreases the activity of hypothalamic AMP-activated protein kinase (AMPK), increases sympathetic nervous system (SNS) activity and upregulates thermogenic markers in brown adipose tissue (BAT). Inhibition of the lipog...

  1. Arctigenin alleviates ER stress via activating AMPK

    Gu, Yuan; Sun, Xiao-xiao; Ye, Ji-Ming; He, Li; Yan, Shou-sheng; Zhang, Hao-hao; Hu, Li-hong; Yuan, Jun-ying; Yu, Qiang

    2012-01-01

    Aim: To investigate the protective effects of arctigenin (ATG), a phenylpropanoid dibenzylbutyrolactone lignan from Arctium lappa L (Compositae), against ER stress in vitro and the underlying mechanisms. Methods: A cell-based screening assay for ER stress regulators was established. Cell viability was measured using MTT assay. PCR and Western blotting were used to analyze gene and protein expression. Silencing of the CaMKKβ, LKB1, and AMPKα1 genes was achieved by RNA interference (RNAi). An A...

  2. Convergence of IPMK and LKB1-AMPK Signaling Pathways on Metformin Action

    Bang, Sookhee; Chen, Yong; Ahima, Rexford S.; Kim, Sangwon F.

    2014-01-01

    Metformin is a biguanide drug that is widely prescribed for type 2 diabetes. Metformin suppresses hepatic gluconeogenesis and increases fatty acid oxidation. Although studies have suggested that metformin acts, at least in part, via activation of the liver kinase B1 (LKB1)/AMP-activated protein kinase (AMPK) pathway, the specific molecular mechanisms underlying metformin's regulation of glucose and lipid metabolism have not been well delineated. Recently, we have shown that inositol polyphosp...

  3. AMPK, a metabolic sensor, is involved in isoeugenol-induced glucose uptake in muscle cells

    Kim, Nami; Lee, Jung Ok; Lee, Hye Jeong; Lee, Yong Woo; Kim, Hyung Ip; Kim, Su Jin; Park, Sun Hwa; Lee, Chul Su; Ryoo, Sun Woo; Hwang, Geum-Sook; Kim, Hyeon Soo

    2016-01-01

    Isoeugenol exerts various beneficial effects on human health. However, the mechanisms underlying these effects are poorly understood. In this study, we observed that isoeugenol activated AMP-activated protein kinase (AMPK) and increased glucose uptake in rat L6 myotubes. Isoeugenol-induced increase in intracellular calcium concentration and glucose uptake was inhibited by STO-609, an inhibitor of calcium/calmodulin-dependent protein kinase kinase (CaMKK). Isoeugenol also increased the phospho...

  4. The effect of an intracerebroventricular injection of metformin or AICAR on the plasma concentrations of melatonin in the ewe: potential involvement of AMPK?

    Collet Armelle

    2011-07-01

    Full Text Available Abstract Background It is now widely accepted that AMP-activated protein kinase (AMPK is a critical regulator of energy homeostasis. Recently, it has been shown to regulate circadian clocks. In seasonal breeding species such as sheep, the circadian clock controls the secretion of an endogenous rhythm of melatonin and, as a consequence, is probably involved in the generation of seasonal rhythms of reproduction. Considering this, we identified the presence of the subunits of AMPK in different hypothalamic nuclei involved in the pre- and post-pineal pathways that control seasonality of reproduction in the ewe and we investigated if the intracerebroventricular (i.c.v. injection of two activators of AMPK, metformin and AICAR, affected the circadian rhythm of melatonin in ewes that were housed in constant darkness. In parallel the secretion of insulin was monitored as a peripheral metabolic marker. We also investigated the effects of i.c.v. AICAR on the phosphorylation of AMPK and acetyl-CoA carboxylase (ACC, a downstream target of AMPK, in brain structures along the photoneuroendocrine pathway to the pineal gland. Results All the subunits of AMPK that we studied were identified in all brain areas that were dissected but with some differences in their level of expression among structures. Metformin and AICAR both reduced (p Conclusions Taken together, these results suggest a potential role for AMPK on the secretion of melatonin probably acting trough the paraventricular nucleus and/or directly in the pineal gland. We conclude that AMPK may act as a metabolic cue to modulate the rhythm of melatonin secretion.

  5. Sucrose nonfermenting AMPK-related kinase (SNARK) mediates contraction-stimulated glucose transport in mouse skeletal muscle

    Koh, Ho-Jin; Toyoda, Taro; Fujii, Nobuharu;

    2010-01-01

    The signaling mechanisms that mediate the important effects of contraction to increase glucose transport in skeletal muscle are not well understood, but are known to occur through an insulin-independent mechanism. Muscle-specific knockout of LKB1, an upstream kinase for AMPK and AMPK....... Whole-body SNARK heterozygotic knockout mice also had impaired contraction-stimulated glucose transport in skeletal muscle, and knockdown of SNARK in C2C12 muscle cells impaired sorbitol-stimulated glucose transport. SNARK is activated by muscle contraction and is a unique mediator of contraction......-stimulated glucose transport in skeletal muscle....

  6. The role of AMP-activated protein kinase in regulation of skeletal muscle metabolism

    Anna Dziewulska; Paweł Dobrzyń; Agnieszka Dobrzyń

    2010-01-01

    AMP-activated protein kinase (AMPK) is a conserved, ubiquitously expressed eukaryotic enzyme that is activated in response to increasing AMP level. Regulation of AMPK activity in skeletal muscle is coordinated by contraction and phosphorylation by upstream kinases and a growing number of hormones and cytokines. Once activated, AMPK turns on catabolic, ATP-generating pathways, and turns off ATP-consuming metabolic processes such as biosynthesis and proliferation. Activation of AMPK promotes gl...

  7. PKC and AMPK regulation of Kv1.5 potassium channels.

    Andersen, Martin Nybo; Skibsbye, Lasse; Tang, Chuyi; Petersen, Frederic; MacAulay, Nanna; Rasmussen, Hanne Borger; Jespersen, Thomas

    2015-01-01

    The voltage-gated Kv1.5 potassium channel, conducting the ultra-rapid rectifier K(+) current (IKur), is regulated through several pathways. Here we investigate if Kv1.5 surface expression is controlled by the 2 kinases PKC and AMPK, using Xenopus oocytes, MDCK cells and atrial derived HL-1 cells. By confocal microscopy combined with electrophysiology we demonstrate that PKC activation reduces Kv1.5 current, through a decrease in membrane expressed channels. AMPK activation was found to decrease the membrane expression in MDCK cells, but not in HL-1 cells and was furthermore shown to be dependent on co-expression of Nedd4-2 in Xenopus oocytes. These results indicate that Kv1.5 channels are regulated by both kinases, although through different molecular mechanisms in different cell systems. PMID:26043299

  8. Linked decreases in Liver Kinase B1 and AMP-activated protein kinase activity modulate matrix catabolic responses to biomechanical injury in chondrocytes

    Petursson, Freyr; Husa, Matt; June, Ron; Lotz, Martin; Terkeltaub, Robert; Liu-Bryan, Ru

    2013-01-01

    Abstract Introduction AMP-activated protein kinase (AMPK) maintains cultured chondrocyte matrix homeostasis in response to inflammatory cytokines. AMPK activity is decreased in human knee osteoarthritis (OA) chondrocytes. Liver kinase B1 (LKB1) is one of the upstream activators of AMPK. Hence, we examined the relationship between LKB1 and AMPK activity in OA and aging cartilages, and in chondrocytes subjected to inflammatory cytokine treatment and biomechanical compression injury, and p...

  9. Liraglutide reduces fatty degeneration in hepatic cells via the AMPK/SREBP1 pathway

    Wang, Yan-Gui; Yang, Tian-lun

    2015-01-01

    Recent studies have suggested that liraglutide could have a potential function in improving non-alcoholic fatty liver disease (NAFLD); however, the underlying molecular mechanism remains unclear. The aim of the present study was to investigate the role of the AMP-activated protein kinase (AMPK)/sterol regulatory element binding protein 1 (SREBP1) pathway in mediating the effect of liraglutide in reducing fatty degeneration in an in vitro NAFLD model. To resemble the NAFLD condition in vitro, ...

  10. Oral glucose ingestion attenuates exercise-induced activation of 5'-AMP-activated protein kinase in human skeletal muscle

    Åkerström, Thorbjörn; Birk, Jesper Bratz; Klein, Ditte Kjærsgaard;

    2006-01-01

    5'-AMP-activated protein kinase (AMPK) has been suggested to be a 'metabolic master switch' regulating various aspects of muscle glucose and fat metabolism. In isolated rat skeletal muscle, glucose suppresses the activity of AMPK and in human muscle glycogen loading decreases exercise-induced AMPK...