Biochemical Regulation of Mammalian AMP-activated Protein Kinase Activity by NAD and NADH

Rafaeloff-Phail, Ronit; Ding, Liyun; Conner, Laura J.; Yeh, Wu-Kuang; McClure, Don B.; Guo, Haihong; Emerson, Kimberlee J.; Brooks, Harold B.

doi:10.1074/jbc.m409574200

Cited by 67 publications

(65 citation statements)

References 28 publications

(29 reference statements)

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“…However, biochemical assays disclosed that GF mice had 72% higher levels of NADϩ (Table 2), which also activates AMPK (10). Similar regulation of AMPK and its targets in both muscle and liver is consistent with recent reports that metabolic crosstalk exists among these distinct tissues (14,15).…”

Section: Gf Mice Have Increased Levels Of Phosphorylated Ampk In Muscsupporting

confidence: 72%

Mechanisms underlying the resistance to diet-induced obesity in germ-free mice

Bäckhed

Manchester²,

Semenkovich

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

2,257

1,744

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The trillions of microbes that colonize our adult intestines function collectively as a metabolic organ that communicates with, and complements, our own human metabolic apparatus. Given the worldwide epidemic in obesity, there is interest in how interactions between human and microbial metabolomes may affect our energy balance. Here we report that, in contrast to mice with a gut microbiota, germ-free (GF) animals are protected against the obesity that develops after consuming a Western-style, high-fat, sugar-rich diet. Their persistently lean phenotype is associated with increased skeletal muscle and liver levels of phosphorylated AMP-activated protein kinase (AMPK) and its downstream targets involved in fatty acid oxidation (acetylCoA carboxylase; carnitinepalmitoyltransferase). Moreover, GF knockout mice lacking fasting-induced adipose factor (Fiaf), a circulating lipoprotein lipase inhibitor whose expression is normally selectively suppressed in the gut epithelium by the microbiota, are not protected from diet-induced obesity. Although GF Fiaf؊/؊ animals exhibit similar levels of phosphorylated AMPK as their wild-type littermates in liver and gastrocnemius muscle, they have reduced expression of genes encoding the peroxisomal proliferatoractivated receptor coactivator (Pgc-1␣) and enzymes involved in fatty acid oxidation. Thus, GF animals are protected from dietinduced obesity by two complementary but independent mechanisms that result in increased fatty acid metabolism: (i) elevated levels of Fiaf, which induces Pgc-1␣; and (ii) increased AMPK activity. Together, these findings support the notion that the gut microbiota can influence both sides of the energy balance equation, and underscore the importance of considering our metabolome in a supraorganismal context. AMP-activated protein kinase ͉ fasting-induced adipose factor ͉ fatty acid metabolism ͉ gut microbiota ͉ symbiosis

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Section: Gf Mice Have Increased Levels Of Phosphorylated Ampk In Muscsupporting

confidence: 72%

Mechanisms underlying the resistance to diet-induced obesity in germ-free mice

Bäckhed

Manchester²,

Semenkovich

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

2,257

1,744

View full text Add to dashboard Cite

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“…Binding of the C-terminal domain with the ␤ and ␥ subunits induces a conformational change in ␣ subunit, which results in an increase in AMPK activity. In addition to regulatory subunits ␤ and ␥, NAD was recently shown to have an activation effect on AMPK (54). However, the details of these mechanisms remain unclear because of a lack of information about the three-dimensional structure of AMPK ␣ catalytic subunit.…”

Section: Discussionmentioning

confidence: 99%

Small Molecule Antagonizes Autoinhibition and Activates AMP-activated Protein Kinase in Cells

Pang

Zhang

et al. 2008

Journal of Biological Chemistry

139

148

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AMP-activated protein kinase (AMPK) serves as an energy sensor and is considered a promising drug target for treatment of type II diabetes and obesity. A previous report has shown that mammalian AMPK ␣1 catalytic subunit including autoinhibitory domain was inactive. To test the hypothesis that small molecules can activate AMPK through antagonizing the autoinhibition in ␣ subunits, we screened a chemical library with inactive human ␣1 394 (␣1, residues 1-394) and found a novel small-molecule activator, PT1, which dose-dependently activated AMPK ␣1 394 , ␣1 335 , ␣2 398 , and even heterotrimer ␣1␤1␥1. Based on PT1-docked AMPK ␣1 subunit structure model and different mutations, we found PT1 might interact with Glu-96 and Lys-156 residues near the autoinhibitory domain and directly relieve autoinhibition. Further studies using L6 myotubes showed that the phosphorylation of AMPK and its downstream substrate, acetyl-CoA carboxylase, were dose-dependently and time-dependently increased by PT1 without an increase in cellular AMP:ATP ratio. Moreover, in HeLa cells deficient in LKB1, PT1 enhanced AMPK phosphorylation, which can be inhibited by the calcium/calmodulin-dependent protein kinase kinases inhibitor STO-609 and AMPK inhibitor compound C. PT1 also lowered hepatic lipid content in a dose-dependent manner through AMPK activation in HepG2 cells, and this effect was diminished by compound C. Taken together, these data indicate that this small-molecule activator may directly activate AMPK via antagonizing the autoinhibition in vitro and in cells. This compound highlights the effort to discover novel AMPK activators and can be a useful tool for elucidating the mechanism responsible for conformational change and autoinhibitory regulation of AMPK.The AMP-activated protein kinase (AMPK) 3 is a highly conserved serine/threonine protein kinase that is widely expressed in higher eukaryotes, yeast, and plants and plays a unique and central role in the responses of cells to metabolic stresses such as nutrient starvation, heat shock, ischemia/hypoxia, and vigorous muscular exercise by depleting cellular ATP and elevating AMP levels (1, 2). Once activated, AMPK prevents depletion of ATP by increasing the rate of ATP generation, triggering changes in the rates of glucose transport, fatty acid oxidation, lipogenesis, sterol synthesis, and gluconeogenesis through direct regulation of key metabolic enzymes and transcriptional control of specific genes (1-4). There is mounting evidence of the involvement of AMPK in human physiological and pathological processes, especially type 2 diabetes and obesity. Previous studies indicate that several of the beneficial effects of rosiglitazone and metformin, two widely used antidiabetic drugs, are mediated by indirect activation of AMPK, suggesting the potential role of the AMPK pathway in the treatment of type 2 diabetes (5, 7). Two adipocyte-derived hormones, leptin and adiponectin, stimulate fatty acid oxidation and glucose uptake in peripheral tissues such as skeletal muscle and liver, whic...

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“…Cells were transfected with appropriate plasmid constructs (SRE-TK-Luc, CA-AMPK, DN-AMPK, and pEGFP-LKB1) by using the LipofectAMINE 2000 (Invitrogen) as recommended by the manufacturer, and they were incubated in 1% serum media with or without OA. pCMV-RL plasmids were other cellular energy and metabolic states, such as glycogen, lipid, and NAD/NADH redox potential (9)(10)(11). However, recent studies have suggested that other unidentifi ed pathways can regulate AMPK, regardless of cellular energy status.…”

Section: Transient Transfection and Reporter Gene Assaymentioning

confidence: 99%

Role of the AMPK/SREBP-1 pathway in the development of orotic acid-induced fatty liver

Jung

Kwon

Jung

et al. 2011

Journal of Lipid Research

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been used as a chemical inducer of fatty liver ( 2, 3 ). Although somewhat inconclusive, the reported mechanisms of OA-induced fatty liver include impairment of fatty acid oxidation, stimulation of lipogenesis, and reduction in lipid transport from the liver ( 4, 5 ). OA-induced fatty liver is species specifi c, and thus far, only the rat has been found to be susceptible. Durschlag and Robinson demonstrated that pharmacokinetic factors determined species specifi city in OA-induced hepatotoxicity ( 6 ). However, the precise molecular mechanism by which OA induces fat accumulation, specifi cally in the rat liver, has remained unclear. Identifi cation of molecular targets of OA effects and susceptibility are of great importance in terms of scientifi c as well as practical aspects. The major source of OA in a typical adult diet is milk and dairy products, which contribute about 0.005% of the total solids, a level at which rats do not show hepatic changes. However, considering the high content of OA in many dietary supplements, vitamin and mineral complexes, and muscle-building products widely sold on the market, we should be wary of possible health effects posed to humans.AMP-activated protein kinase (AMPK), a heterotrimeric enzyme complex, is the key regulator of energy metabolism in cells. The energy-sensing motif of the enzyme monitors the energy status of cells and controls its activity by phosphorylation at T172 ( 7 ). In the liver, activation of AMPK phosphorylates and inactivates the rate-limiting enzymes of lipogenesis, such as acetyl-CoA carboxylase (ACC) ( 8 ). AMPK is classically regulated by various metabolic stresses that cause an increase in the AMP/ATP ratio or Induction of fatty liver in rats by orotic acid (OA; 6-carboxyuracil) administration was fi rst observed in 1955 ( 1 ).

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Biochemical Regulation of Mammalian AMP-activated Protein Kinase Activity by NAD and NADH

Cited by 67 publications

References 28 publications

Mechanisms underlying the resistance to diet-induced obesity in germ-free mice

Mechanisms underlying the resistance to diet-induced obesity in germ-free mice

Small Molecule Antagonizes Autoinhibition and Activates AMP-activated Protein Kinase in Cells

Role of the AMPK/SREBP-1 pathway in the development of orotic acid-induced fatty liver

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