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Dehydrozingerone exerts beneficial metabolic effects in high-fat diet-induced obese mice viaAMPK activation in skeletal muscle

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      Abstract

      Dehydrozingerone (DHZ) exerts beneficial effects on human health; however, its mechanism of action remains unclear. Here, we found that DHZ suppressed high-fat diet-induced weight gain, lipid accumulation and hyperglycaemia in C57BL/6 mice and increased AMP-activated protein kinase (AMPK) phosphorylation and stimulated glucose uptake in C2C12 skeletal muscle cells. DHZ activated p38 mitogen-activated protein kinase (MAPK) signalling in an AMPK-dependent manner. Inhibiting AMPK or p38 MAPK blocked DHZ-induced glucose uptake. DHZ increased GLUT4 (major transporter for glucose uptake) expression in skeletal muscle. Glucose clearance and insulin-induced glucose uptake increased in DHZ-fed animals, suggesting that DHZ increases systemic insulin sensitivity in vivo. Thus, the beneficial health effects of DHZ could possibly be explained by its ability to activate the AMPK pathway in skeletal muscle.

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      Most cited references 36

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      AMP-activated protein kinase: ancient energy gauge provides clues to modern understanding of metabolism.

      The AMP-activated protein kinase (AMPK) is an evolutionarily conserved sensor of cellular energy status, and recent data demonstrate that it also plays a critical role in systemic energy balance. AMPK integrates nutritional and hormonal signals in peripheral tissues and the hypothalamus. It mediates effects of adipokines (leptin, adiponectin, and possibly resistin) in regulating food intake, body weight, and glucose and lipid homeostasis. AMPK is regulated by upstream kinases of which the tumor suppressor, LKB1, is the first to be identified. Complex signaling networks suggest that AMPK may prevent insulin resistance, in part by inhibiting pathways that antagonize insulin signaling. Through signaling, metabolic, and gene expression effects, AMPK enhances insulin sensitivity and fosters a metabolic milieu that may reduce the risk for obesity and type 2 diabetes.
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        Complexes between the LKB1 tumor suppressor, STRADα/β and MO25α/β are upstream kinases in the AMP-activated protein kinase cascade

        Background The AMP-activated protein kinase (AMPK) cascade is a sensor of cellular energy charge that acts as a 'metabolic master switch' and inhibits cell proliferation. Activation requires phosphorylation of Thr172 of AMPK within the activation loop by upstream kinases (AMPKKs) that have not been identified. Recently, we identified three related protein kinases acting upstream of the yeast homolog of AMPK. Although they do not have obvious mammalian homologs, they are related to LKB1, a tumor suppressor that is mutated in the human Peutz-Jeghers cancer syndrome. We recently showed that LKB1 exists as a complex with two accessory subunits, STRADα/β and MO25α/β. Results We report the following observations. First, two AMPKK activities purified from rat liver contain LKB1, STRADα and MO25α, and can be immunoprecipitated using anti-LKB1 antibodies. Second, both endogenous and recombinant complexes of LKB1, STRADα/β and MO25α/β activate AMPK via phosphorylation of Thr172. Third, catalytically active LKB1, STRADα or STRADβ and MO25α or MO25β are required for full activity. Fourth, the AMPK-activating drugs AICA riboside and phenformin do not activate AMPK in HeLa cells (which lack LKB1), but activation can be restored by stably expressing wild-type, but not catalytically inactive, LKB1. Fifth, AICA riboside and phenformin fail to activate AMPK in immortalized fibroblasts from LKB1-knockout mouse embryos. Conclusions These results provide the first description of a physiological substrate for the LKB1 tumor suppressor and suggest that it functions as an upstream regulator of AMPK. Our findings indicate that the tumors in Peutz-Jeghers syndrome could result from deficient activation of AMPK as a consequence of LKB1 inactivation.
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          The AMP-activated/SNF1 protein kinase subfamily: metabolic sensors of the eukaryotic cell?

          Mammalian AMP-activated protein kinase and yeast SNF1 protein kinase are the central components of kinase cascades that are highly conserved between animals, fungi, and plants. The AMP-activated protein kinase cascade acts as a metabolic sensor or "fuel gauge" that monitors cellular AMP and ATP levels because it is activated by increases in the AMP:ATP ratio. Once activated, the enzyme switches off ATP-consuming anabolic pathways and switches on ATP-producing catabolic pathways, such as fatty acid oxidation. The SNF1 complex in yeast is activated in response to the stress of glucose deprivation. In this case the intracellular signal or signals have not been identified; however, SNF1 activation is associated with depletion of ATP and elevation of AMP. The SNF1 complex acts primarily by inducing expression of genes required for catabolic pathways that generate glucose, probably by triggering phosphorylation of transcription factors. SNF1-related protein kinases in higher plants are likely to be involved in the response of plant cells to environmental and/or nutritional stress.
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            Author and article information

            Affiliations
            [a ]Department of Anatomy, Korea University College of Medicine Seoul, South Korea
            [b ]Department of Internal Medicine, Yonsei University Wonju College of Medicine Wonju, South Korea
            [c ]Seoul Science High School Seoul, South Korea
            Author notes
            Correspondence to: Hyeon Soo KIM, Department of Anatomy, Korea University College of Medicine, Seoul 136-701, Korea., Tel.: 82-2-920-6151, Fax: 82-2-929-5696, E-mail: anatomykim@ 123456korea.ac.kr
            Journal
            J Cell Mol Med
            J. Cell. Mol. Med
            jcmm
            Journal of Cellular and Molecular Medicine
            BlackWell Publishing Ltd (Oxford, UK )
            1582-1838
            1582-4934
            March 2015
            12 January 2015
            : 19
            : 3
            : 620-629
            25582026
            4369818
            10.1111/jcmm.12455
            © 2015 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

            This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

            Categories
            Original Articles

            Molecular medicine

            glucose uptake, metabolism, dehydrozingerone, curcumin analogue, ampk

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