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In obesity and type 2 diabetes, Glut4 glucose transporter expression is decreased selectively in adipocytes (1). Adipose-specific knockout or overexpression of Glut4 alters systemic insulin sensitivity (2). Here we show, using DNA array analyses, that nicotinamide N-methyltransferase (Nnmt) is the most strongly reciprocally regulated gene when comparing gene expression in white adipose tissue (WAT) from adipose-specific Glut4-knockout or adipose-specific Glut4-overexpressing mice with their respective controls. NNMT methylates nicotinamide (vitamin B3) using S-adenosylmethionine (SAM) as a methyl donor (3,4). Nicotinamide is a precursor of [NAD.sup.+], an important cofactor linking cellular redox states with energy metabolism (5). SAM provides propylamine for polyamine biosynthesis and donates a methyl group for histone methylation (6). Polyamine flux including synthesis, catabolism and excretion, is controlled by the rate-limiting enzymes ornithine decarboxylase (ODC) and spermidine-spermine N1-acetyltransferase (SSAT; encoded by Satl) and by polyamine oxidase (PAO), and has a major role in energy metabolism (7,8). We report that NNMT expression is increased in WAT and liver of obese and diabetic mice. Nnmt knockdown in WAT and liver protects against diet-induced obesity by augmenting cellular energy expenditure. NNMT inhibition increases adipose SAM and [NAD.sup.+] levels and upregulates ODC and SSAT activity as well as expression, owing to the effects of NNMT on histone H3 lysine 4 methylation in adipose tissue. Direct evidence for increased polyamine flux resulting from NNMT inhibition includes elevated urinary excretion and adipocyte secretion of diacetylspermine, a product of polyamine metabolism. NNMT inhibition in adipocytes increases oxygen consumption in an ODC-, SSAT- and PAO-dependent manner. Thus, NNMT is a novel regulator of histone methylation, polyamine flux and [NAD.sup.+]-dependent SIRT1 signalling, and is a unique and attractive target for treating obesity and type 2 diabetes., Nnmt is expressed at high levels in adipose tissue and liver and at lower levels in other organs (3,4). Nnmt is increased in multiple cancers (9,10), neuro-degenerative diseases (11), and [...]

Normal epithelial cells require matrix attachment for survival, and the ability of tumour cells to survive outside their natural extra-cellular matrix (ECM) niches is dependent on acquisition of anchorage independence [...]

AMP-activated protein kinase (AMPK) is a metabolic fuel gauge conserved along the evolutionary scale in eukaryotes that senses changes in the intracellular AMP/ATP ratio (1). Recent evidence indicated an important role for AMPK in the therapeutic benefits of metformin (2,3), thiazolidinediones (4) and exercise (5), which form the cornerstones of the clinical management of type 2 diabetes and associated metabolic disorders. In general, activation of AMPK acts to maintain cellular energy stores, switching on catabolic pathways that produce ATP, mostly by enhancing oxidative metabolism and mitochondrial biogenesis, while switching off anabolic pathways that consume ATP (1). This regulation can take place acutely, through the regulation of fast post-translational events, but also by transcriptionally reprogramming the cell to meet energetic needs. Here we demonstrate that AMPK controls the expression of genes involved in energy metabolism in mouse skeletal muscle by acting in coordination with another metabolic sensor, the [NAD.sup.+]-dependent type III deacetylase SIRT1. AMPK enhances SIRT1 activity by increasing cellular [NAD.sup.+] levels, resulting in the deacetylation and modulation of the activity of downstream SIRT1 targets that include the peroxisome proliferator-activated receptor-γ coactivator 1αand the forkhead box O1 (FOXO1) and 03 (FOXO3a) transcription factors. The AMPK-induced SIRT1-mediated deacetylation of these targets explains many of the convergent biological effects of AMPK and SIRT1 on energy metabolism., AMPK is a critical regulator of mitochondrial biogenesis in response to energy deprivation (6). Although the mechanisms by which AMPK modulates mitochondrial gene expression are not entirely elucidated, they seem [...]

Transcriptional control of metabolic circuits requires coordination between specific transcription factors and coregulators and is often deregulated in metabolic diseases. We characterized here the mechanisms through which the coactivator SRC-3 controls energy homeostasis. SRC-3 knock-out mice present a more favorable metabolic profile relative to their wild-type littermates. This metabolic improvement in [SRC-3.sup.-/-] mice is caused by an increase in mitochondrial function and in energy expenditure as a consequence of activation of PGC-1[alpha]. By controlling the expression of the only characterized PGC-1[alpha] acetyltransferase GCN5, SRC-3 induces PGC-1[alpha] acetylation and consequently inhibits its activity. Interestingly, SRC-3 expression is induced by caloric excess, resulting in the inhibition of PGC-1[alpha] activity and energy expenditure, whereas caloric restriction reduces SRC-3 levels leading to enhanced PGC-1[alpha] activity and energy expenditure. Collectively, these data suggest that SRC-3 is a critical link in a cofactor network that uses PGC-1[alpha] as an effector to control mitochondrial function and energy homeostasis. acetyltransferase | caloric restriction | cofactors | deacetylase | SIRT1

Author(s): John T. Cunningham [1, 2]; Joseph T. Rodgers [1]; Daniel H. Arlow [3]; Francisca Vazquez [1]; Vamsi K. Mootha (corresponding author) [3]; Pere Puigserver (corresponding author) [1, 2] Transcriptional [...]

Transcriptional complexes that contain peroxisome-proliferator-activated receptor coactivator (PGC)-1α control mitochondrial oxidative function to maintain energy homeostasis in response to nutrient and hormonal signals (1,2). An important component in the energy [...]

In the fasted state, induction of hepatic glucose output and fatty acid oxidation is essential to sustain energetic balance. Production and oxidation of glucose and fatty acids by the liver are controlled through a complex network of transcriptional regulators. Among them, the transcriptional coactivator PGC-1[alpha] plays an important role in hepatic and systemic glucose and lipid metabolism. We have previously demonstrated that sirtuin 1 (SIRT1) regulates genes involved in gluconeogenesis through interaction and deacetylation of PGC-1[alpha]. Here, we show in vivo that hepatic SIRT1 is a factor in systemic and hepatic glucose, lipid, and cholesterol homeostasis. Knockdown of SIRT1 in liver caused mild hypoglycemia, increased systemic glucose and insulin sensitivity, and decreased glucose production. SIRT1 knockdown also decreased serum cholesterol and increased hepatic free fatty acid and cholesterol content. These metabolic phenotypes caused by SIRT1 knockdown tightly correlated with decreased expression of gluconeogenic, fatty acid oxidation and cholesterol degradation as well as efflux genes. Additionally, overexpression of SIRT1 reversed many of the changes caused by SIRT1 knockdown and depended on the presence of PGC-1[alpha]. Interestingly, most of the effects of SIRT1 were only apparent in the fasted state. Our results indicate that hepatic SIRT1 is an important factor in the regulation of glucose and lipid metabolism in response to nutrient deprivation. As these pathways are dysregulated in metabolic diseases, SIRT1 may be a potential therapeutic target to control hyperglycemia and hypercholesterolemia. fasting response | glucose metabolism | lipid metabolism | deacetylase | transcriptional coactivator

Previous investigations show that intracerebroventricular administration of a potent inhibitor of fatty acid synthase, C75, increases the level of its substrate, malonyl-CoA, in the hypothalamus. The 'malonyl-CoA signal' is rapidly transmitted to skeletal muscle by the sympathetic nervous system, increasing fatty acid oxidation, uncoupling protein-3 (UCP3) expression, and thus, energy expenditure. Here, we show that intracerebroventricular or intraperitoneal administration of C75 increases the number of mitochondria in white and red (soleus) skeletal muscle. Consistent with signal transmission from the hypothalamus by the sympathetic nervous system, centrally administered C75 rapidly ([less than or equal to] 2 h) up-regulated the expression (in skeletal muscle) of the [beta]-adrenergic signaling molecules, i.e., norepinephrine, [[beta].sub.3]-adrenergic receptor, and cAMP; the transcriptional regulators peroxisomal proliferator activator regulator [gamma] coactivator 1[alpha] (PGC-1[alpha]) and estrogen receptor-related receptor [alpha](ERR[alpha]); and the expression of key oxidative mitochondrial enzymes, including pyruvate dehydrogenase kinase, medium-chain length fatty acyl-CoA dehydrogenase, ubiquinone-cytochrome c reductase, cytochrome oxidase, as well as ATP synthase and UCP3. The role of PGC-1[alpha] in mediating these responses in muscle was assessed with C2C12 myocytes in cell culture. Consistent with the in vivo response, adenovirus-directed expression of PGC-1[alpha] in C2C12 muscle cells provoked the phosphorylation/ inactivation and reduced expression of acetyl-CoA carboxylase 2, causing a reduction of the malonyl-CoA concentration. These effects, coupled with an increased carnitine palmitoyltransferase 1b, led to increased fatty acid oxidation. PGC-1[alpha] also increased the expression of ERR[alpha], PPAR[alpha], and enzymes that support mitochondrial fatty acid oxidation, ATP synthesis, and thermogenesis, apparently mediated by an increased expression of UCP3. C75 | energy expenditure | sympathetic nervous system | uncoupling protein 3 | C2C12 myocytes

Author(s): Joseph T. Rodgers [1]; Carlos Lerin [1]; Wilhelm Haas [3]; Steven P. Gygi [3]; Bruce M. Spiegelman [2, 3]; Pere Puigserver (corresponding author) [1] Homeostatic mechanisms in mammals respond [...]

Recent studies have shown that genes involved in oxidative phosphorylation (OXPHOS) exhibit reduced expression in skeletal muscle of diabetic and prediabetic humans. Moreover, these changes may be mediated by the transcriptional coactivator peroxisome proliferator-activated receptor [gamma] coactivator-1[alpha] (PGC-1[alpha]). By combining PGC-1[alpha]-induced genome-wide transcriptional profiles with a computational strategy to detect cis-regulatory motifs, we identified estrogen-related receptor [alpha] (Err[alpha]) and GA repeat-binding protein [alpha] as key transcription factors regulating the OXPHOS pathway. Interestingly, the genes encoding these two transcription factors are themselves PGC-1[alpha]-inducible and contain variants of both motifs near their prometers. Cellular assays confirmed that Err[alpha] and GA-binding protein a partner with PGC-1[alpha] in muscle to form a double-positive-feedback loop that drives the expression of many OXPHOS genes. By using a synthetic inhibitor of Err[alpha], we demonstrated its key role in PGC-1[alpha]-mediated effects on gene regulation and cellular respiration. These results illustrate the dissection of gene regulatory networks in a complex mammalian system, elucidate the mechanism of PGC-1[alpha] action in the OXPHOS pathway, and suggest that Err[alpha] agonists may ameliorate insulin-resistance in individuals with type 2 diabetes mellitus.

Author(s): Pere Puigserver [1, 2]; James Rhee [1]; Jerry Donovan [1]; Christopher J. Walkey [1]; J. Cliff Yoon [1]; Francesco Oriente [3]; Yukari Kitamura [3]; Jennifer Altomonte [4]; Hengjiang Dong [...]

The liver plays several critical roles in the metabolic adaptation to fasting. We have shown previously that the transcriptional coactivator peroxisome proliferator-activated receptor [gamma] coactivator-1[alpha] (PGC-1[alpha]) is induced in fasted or diabetic liver and activates the entire program of gluconeogenesis. PGC-1[alpha] interacts with several nuclear receptors known to bind gluconeogenic promoters including the glucocorticoid receptor, hepatocyte nuclear factor 4[alpha] (HNF4[alpha]), and the peroxisome proliferator-activated receptors. However, the genetic requirement for any of these interactions has not been determined. Using hepatocytes from mice lacking HNF4[alpha] in the liver, we show here that PGC-1[alpha] completely loses its ability to activate key genes of gluconeogenesis such as phosphoenol-pyruvate carboxykinase and glucose-6-phosphatase when HNF4[alpha] is absent. It is also shown that PGC-1[alpha] can induce genes of [beta]-oxidation and ketogenesis in hepatocytes, but these effects do not require HNF4[alpha]. Analysis of the glucose-6-phosphatase promoter indicates a key role for HNF4[alpha]-binding sites that function robustly only when HNF4[alpha] is coactivated by PGC-1[alpha]. These data illustrate the involvement of PGC-1[alpha] in several aspects of the hepatic fasting response and show that HNF4[alpha] is a critical component of PGC-1[alpha]-mediated gluconeogenesis.

Author(s): Jiandie Lin [1]; Hai Wu [2]; Paul T. Tarr [1]; Chen-Yu Zhang [3]; Zhidan Wu [1]; Olivier Boss [3]; Laura F. Michael [1]; Pere Puigserver [1]; Eiji Isotani [4]; [...]

Author(s): Stephan Herzig [1]; Fanxin Long [1, 2]; Ulupi S. Jhala [1]; Susan Hedrick [1]; Rebecca Quinn [3]; Anton Bauer [4]; Dorothea Rudolph [4]; Gunther Schutz [4]; Cliff Yoon [5]; [...]

Author(s): J. Cliff Yoon [1]; Pere Puigserver [1]; Guoxun Chen [2]; Jerry Donovan [1]; Zhidan Wu [1]; James Rhee [1]; Guillaume Adelmant [1]; John Stafford [3]; C. Ronald Kahn [4]; [...]

Author(s): Chi Luo [1]; Ji-Hong Lim [1]; Yoonjin Lee [1, 2]; Scott R. Granter [3]; Ajith Thomas [1]; Francisca Vazquez [1, 4, 5]; Hans R. Widlund [6]; Pere Puigserver (corresponding [...]

Author(s): Yoonjin Lee [1, 2, 3]; John E. Dominy [1, 2]; Yoon Jong Choi [1, 4]; Michael Jurczak [5]; Nicola Tolliday [6]; Joao Paulo Camporez [5]; Helen Chim [1, 2]; [...]

Author(s): Chi Luo [1]; Pere Puigserver (corresponding author) [1] Excess food intake causes obesity and is linked to many life-threatening diseases, including cardiovascular disease and cancer [1]. Ingested dietary components [...]

Author(s): Joseph A. Baur [1, 13]; Kevin J. Pearson [2, 13]; Nathan L. Price [2]; Hamish A. Jamieson [7]; Carles Lerin [8]; Avash Kalra [2]; Vinayakumar V. Prabhu [3]; Joanne [...]

Muscle tissue is the major site for insulin-stimulated glucose uptake in vivo, due primarily to the recruitment of the insulin-sensitive glucose transporter (GLUT4) to the plasma membrane. Surprisingly, virtually all cultured muscle cells express little or no GLUT4. We show here that adenovirus-mediated expression of the transcriptional coactivator PGC-1, which is expressed in muscle in vivo but is also deficient in cultured muscle cells, causes the total restoration of GLUT4 mRNA levels to those observed in vivo. This increased GLUT4 expression correlates with a 3-fold increase in glucose transport, although much of this protein is transported to the plasma membrane even in the absence of insulin. PGC-1 mediates this increased GLUT4 expression, in large part, by binding to and coactivating the muscle-selective transcription factor MEF2C. These data indicate that PGC-1 is a coactivator of MEF2C and can control the level of endogenous GLUT4 gene expression in muscle. MEF2 | diabetes

Transcriptional coactivators have been viewed as constitutively active components, using transcription factors mainly to localize their functions. Here, it is shown that PPAR[Gamma] coactivator-1 (PGC-1) promotes transcription through the assembly of a complex that includes the histone acetyltransferases steroid receptor coactivator-1 (SRC-1) and CREB binding protein (CBP)/p300. PGC-1 has a low inherent transcriptional activity when it is not bound to a transcription factor. The docking of PGC-1 to peroxisome proliferator-activated receptor [Gamma] (PPAR[Gamma]) stimulates an apparent conformational change in PGC-1 that permits binding of SRC-1 and CBP/p300, resulting in a large increase in transcriptional activity. Thus, transcription factor docking switches on the activity of a coactivator protein., Transcription factors exert their effects through docking of coactivator or corepressor proteins. Coactivators belong to two broad classes. In the first class, proteins like the SRC and CBP/p300 families contain [...]

Author(s): Stephan Herzig; Fanxin Long; Ulupi S. Jhala; Susan Hedrick; Rebecca Quinn; Anton Bauer; Dorothea Rudolph; Gunther Schutz; Cliff Yoon; Pere Puigserver; Bruce Spiegelman; Marc Montminy Nature, 413, 179-183 (2001). [...]