Antonio Vidal-Puig | University of Cambridge (original) (raw)

Papers by Antonio Vidal-Puig

PLoS Biology, 2011

Identification of early mechanisms that may lead from obesity towards complications such as metab... more Identification of early mechanisms that may lead from obesity towards complications such as metabolic syndrome is of great interest. Here we performed lipidomic analyses of adipose tissue in twin pairs discordant for obesity but still metabolically compensated. In parallel we studied more evolved states of obesity by investigating a separated set of individuals considered to be morbidly obese. Despite lower dietary polyunsaturated fatty acid intake, the obese twin individuals had increased proportions of palmitoleic and arachidonic acids in their adipose tissue, including increased levels of ethanolamine plasmalogens containing arachidonic acid. Information gathered from these experimental groups was used for molecular dynamics simulations of lipid bilayers combined with dependency network analysis of combined clinical, lipidomics, and gene expression data. The simulations suggested that the observed lipid remodeling maintains the biophysical properties of lipid membranes, at the price, however, of increasing their vulnerability to inflammation. Conversely, in morbidly obese subjects, the proportion of plasmalogens containing arachidonic acid in the adipose tissue was markedly decreased. We also show by in vitro Elovl6 knockdown that the lipid network regulating the observed remodeling may be amenable to genetic modulation. Together, our novel approach suggests a physiological mechanism by which adaptation of adipocyte membranes to adipose tissue expansion associates with positive energy balance, potentially leading to higher vulnerability to inflammation in acquired obesity. Further studies will be needed to determine the cause of this effect.

Diabetes, 2005

The nuclear receptor peroxisome proliferator–activated receptor-γ (PPARγ) is critically required ... more The nuclear receptor peroxisome proliferator–activated receptor-γ (PPARγ) is critically required for adipogenesis. PPARγ exists as two isoforms, γ1 and γ2. PPARγ2 is the more potent adipogenic isoform in vitro and is normally restricted to adipose tissues, where it is regulated more by nutritional state than PPARγ1. To elucidate the relevance of the PPARγ2 in vivo, we generated a mouse model in which the PPARγ2 isoform was specifically disrupted. Despite similar weight, body composition, food intake, energy expenditure, and adipose tissue morphology, male mice lacking the γ2 isoform were more insulin resistant than wild-type animals when fed a regular diet. These results indicate that insulin resistance associated with ablation of PPARγ2 is not the result of lipodystrophy and suggests a specific role for PPARγ2 in maintaining insulin sensitivity independently of its effects on adipogenesis. Furthermore, PPARγ2 knockout mice fed a high-fat diet did not become more insulin resistant t...

Nature medicine, 2010

Thyroid hormones are well known to regulate whole-body energy metabolism, which was believed to o... more Thyroid hormones are well known to regulate whole-body energy metabolism, which was believed to occur as a direct effect on individual cells in the periphery. But Antonio Vidal-Puig and his colleagues now show that these thyroid hormone effects on energy regulation are actually ...

PloS one, 2012

Mice lacking Peroxisome Proliferator-Activated Receptor c2 (PPARc2) have unexpectedly normal gluc... more Mice lacking Peroxisome Proliferator-Activated Receptor c2 (PPARc2) have unexpectedly normal glucose tolerance and mild insulin resistance. Mice lacking PPARc2 were found to have elevated levels of Lipocalin prostaglandin D synthase (L-PGDS) expression in BAT and subcutaneous white adipose tissue (WAT). To determine if induction of L-PGDS was compensating for a lack of PPARc2, we crossed L-PGDS KO mice to PPARc2 KO mice to generate Double Knock Out mice (DKO). Using DKO mice we demonstrated a requirement of L-PGDS for maintenance of subcutaneous WAT (scWAT) function. In scWAT, DKO mice had reduced expression of thermogenic genes, the de novo lipogenic program and the lipases ATGL and HSL. Despite the reduction in markers of lipolysis in scWAT, DKO mice had a normal metabolic rate and elevated serum FFA levels compared to L-PGDS KO alone. Analysis of intra-abdominal white adipose tissue (epididymal WAT) showed elevated expression of mRNA and protein markers of lipolysis in DKO mice, suggesting that DKO mice may become more reliant on intra-abdominal WAT to supply lipid for oxidation. This switch in depot utilisation from subcutaneous to epididymal white adipose tissue was associated with a worsening of whole organism metabolic function, with DKO mice being glucose intolerant, and having elevated serum triglyceride levels compared to any other genotype. Overall, L-PGDS and PPARc2 coordinate to regulate carbohydrate and lipid metabolism.

Diabetes, Aug 6, 2013

The epidemic of obesity imposes unprecedented challenges on human adipose tissue (WAT) storage ca... more The epidemic of obesity imposes unprecedented challenges on human adipose tissue (WAT) storage capacity that may benefit from adaptive mechanisms to maintain adipocyte functionality. Here, we demonstrate that changes in the regulatory feedback set point control of Insig1/SREBP1 represent an adaptive response that preserves WAT lipid homeostasis in obese and insulinresistant states. In our experiments, we show that Insig1 mRNA expression decreases in WAT from mice with obesity-associated insulin resistance and from morbidly obese humans and in in vitro models of adipocyte insulin resistance. Insig1 downregulation is part of an adaptive response that promotes the maintenance of SREBP1 maturation and facilitates lipogenesis and availability of appropriate levels of fatty acid unsaturation, partially compensating the antilipogenic effect associated with insulin resistance. We describe for the first time the existence of this adaptive mechanism in WAT, which involves Insig1/SREBP1 and preserves the degree of lipid unsaturation under conditions of obesity-induced insulin resistance. These adaptive mechanisms contribute to maintain lipid desaturation through preferential SCD1 regulation and facilitate fat storage in WAT, despite ongoing metabolic stress. Diabetes 62:3697-3708, 2013 T he epidemic of obesity is testing the capacity of white adipose tissue (WAT) to cope with an unprecedented nutritional pressure and demand to expand. We and others have proposed that the expansion and dysfunction of WAT may be an important pathogenic contributor to obesity-associated metabolic complications (1). However, a recurrent observation from clinical studies is that obese patients maintain a remarkable capacity to store fat before adverse metabolic effects occur. Moreover, we have recently demonstrated, using a monozygotic twin cohort discordant for obesity, that while expanding, the WAT adapts its biochemical features to maintain its biophysical characteristics and preserves its functionality by increasing the degree of fatty acid (FA) unsaturation and chain length in adipocyte membrane phospholipids (PLs). This implies the existence of adaptive homeostatic mechanisms that preserve WAT functionality (2).

Biochemical and Biophysical Research Communications, 2002

Activation of the canonical Wnt signalling pathway results in stabilisation and nuclear transloca... more Activation of the canonical Wnt signalling pathway results in stabilisation and nuclear translocation of beta-catenin. In the absence of a Wnt signal, beta-catenin is phosphorylated at four conserved serine and threonine residues at the N-terminus of the protein, which results in beta-catenin ubiquitination and proteasome-dependent degradation. The phosphorylation of three of these residues, Thr41, Ser37, and Ser33, is mediated by glycogen synthase kinase-3 (GSK-3) in a sequential manner, beginning from the C-terminal Thr41. It has recently been shown that the GSK-3 dependent phosphorylation of beta-catenin requires prior priming through phosphorylation of Ser45. However, it is not known whether phosphorylation of Ser45 is carried out by GSK-3 itself or by an alternative kinase. In this study, the phosphorylation of beta-catenin at Ser45 was characterised using a phospho-specific antibody. GSK-3beta was found to be unable to phosphorylate beta-catenin at Ser45 in vitro and in intact cells. However, inhibition of GSK-3 in intact cells reduced Ser45 phosphorylation, suggesting that GSK-3 kinase activity is required for the phosphorylation event. In vitro, CK1, but not CK2, phosphorylates Ser45. Ser45 phosphorylation in intact cells is not mediated by CK1varepsilon, a known positive regulator of Wnt signalling, as overexpression of this kinase leads to decreased phosphorylation levels. In conclusion, phosphorylation of beta-catenin at the GSK-3 priming site Ser45 is not mediated by GSK-3 itself, but by an alternative kinase, indicating that beta-catenin is not an unprimed substrate for GSK-3 in vivo. Priming of GSK-3 dependent phosphorylation of beta-catenin by a different kinase could have important implications for the regulation of Wnt signalling.

Biochemical and Biophysical Research Communications, 1999

Administration of ␤-adrenergic receptor (␤-AR) agonists, especially ␤ 3 -AR agonists, is well kno... more Administration of ␤-adrenergic receptor (␤-AR) agonists, especially ␤ 3 -AR agonists, is well known to increase thermogenesis in rodents and humans. In this work we studied the role of the ␤ 3 -AR in regulating mRNA expression of genes involved in thermogenesis, i.e., mitochondrial uncoupling proteins UCP2 and UCP3, and peroxisome proliferator-activated receptor-␥ coactivator-1 (PGC-1), in mouse skeletal muscle. For this purpose, different ␤ 3 -AR agonists were administered acutely to both wild type mice and mice whose ␤ 3 -AR gene has been disrupted (␤ 3 -AR KO mice). CL 316243 increased the expression of UCP2, UCP3 and PGC-1 in wild type mice only. By contrast, BRL 37344 and CGP 12177 increased the expression of UCP2 and UCP3 in both wild type and ␤ 3 -AR KO mice, whereas they increased the expression of PGC-1 in wild type mice only. Finally, acute (3 h) cold exposure increased the expression of UCP2 and UCP3, but not PGC-1, in skeletal muscle of both wild type and ␤ 3 -AR KO mice. These results show that selective stimulation of the ␤ 3 -AR affects the expression of UCP2, UCP3 and PGC-1 in skeletal muscle. This effect is probably indirect, as muscle does not seem to express ␤ 3 -AR. In addition, our data suggest that BRL 37344 and CGP 12177 act, in part, through an as yet unidentified receptor, possibly a ␤ 4 -AR.

Journal of Biological Chemistry, 2000

Uncoupling protein 3 (UCP3) is a member of the mitochondrial anion carrier superfamily. Based upo... more Uncoupling protein 3 (UCP3) is a member of the mitochondrial anion carrier superfamily. Based upon its high homology with UCP1 and its restricted tissue distribution to skeletal muscle and brown adipose tissue, UCP3 has been suggested to play important roles in regulating energy expenditure, body weight, and thermoregulation. Other postulated roles for UCP3 include regulation of fatty acid metabolism, adaptive responses to acute exercise and starvation, and prevention of reactive oxygen species (ROS) formation. To address these questions, we have generated mice lacking UCP3 (UCP3 knockout (KO) mice). Here, we provide evidence that skeletal muscle mitochondria lacking UCP3 are more coupled (i.e. increased state 3/state 4 ratio), indicating that UCP3 has uncoupling activity. In addition, production of ROS is increased in mitochondria lacking UCP3. This study demonstrates that UCP3 has uncoupling activity and that its absence may lead to increased production of ROS. Despite these effects on mitochondrial function, UCP3 does not seem to be required for body weight regulation, exercise tolerance, fatty acid oxidation, or cold-induced thermogenesis. The absence of such phenotypes in UCP3 KO mice could not be attributed to up-regulation of other UCP mRNAs. However, alternative compensatory mechanisms cannot be excluded. The consequence of increased mitochondrial coupling in UCP3 KO mice on metabolism and the possible role of yet unidentified compensatory mechanisms, remains to be determined.

Expert Review of Molecular Diagnostics, 2006

Metabolites are the key regulators of systems homeostasis. As such, concentration changes of spec... more Metabolites are the key regulators of systems homeostasis. As such, concentration changes of specific groups of metabolites may reflect systemic responses to environmental, therapeutic or genetic interventions. Thus, the study of metabolites is a powerful tool for the characterization of complex phenotypes as well as for the development of biomarkers for specific physiological responses. Therefore, metabolomics is a valuable platform for studies of complex diseases and the development of new therapies, both in nonclinical disease model characterization and clinical settings.

BMC Systems Biology, 2007

Background: Lipids are an important and highly diverse class of molecules having structural, ener... more Background: Lipids are an important and highly diverse class of molecules having structural, energy storage and signaling roles. Modern analytical technologies afford screening of many lipid molecular species in parallel. One of the biggest challenges of lipidomics is elucidation of important pathobiological phenomena from the integration of the large amounts of new data becoming available.

Proceedings of The National Academy of Sciences, 2004

Nuclear receptors and their coactivators have been shown to function as key regulators of adipose... more Nuclear receptors and their coactivators have been shown to function as key regulators of adipose tissue biology. Here we show that a ligand-dependent transcriptional repressor for nuclear receptors plays a crucial role in regulating the balance between energy storage and energy expenditure. Mice devoid of the corepressor protein RIP140 are lean, show resistance to high-fat diet-induced obesity and hepatic steatosis, and have increased oxygen consumption. Although the process of adipogenesis is unaffected, expression of certain lipogenic enzymes is reduced. In contrast, genes involved in energy dissipation and mitochondrial uncoupling, including uncoupling protein 1, are markedly increased. Therefore, the maintenance of energy homeostasis requires the action of a transcriptional repressor in white adipose tissue, and ligand-dependent recruitment of RIP140 to nuclear receptors may provide a therapeutic target in the treatment of obesity and related disorders.

Journal of Clinical Investigation, 2007

Central nervous system control of energy balance affects susceptibility to obesity and diabetes, ... more Central nervous system control of energy balance affects susceptibility to obesity and diabetes, but how fatty acids, malonyl-CoA, and other metabolites act at this site to alter metabolism is poorly understood. Pharmacological inhibition of fatty acid synthase (FAS), rate limiting for de novo lipogenesis, decreases appetite independently of leptin but also promotes weight loss through activities unrelated to FAS inhibition. Here we report that the conditional genetic inactivation of FAS in pancreatic β cells and hypothalamus produced lean, hypophagic mice with increased physical activity and impaired hypothalamic PPARα signaling. Administration of a PPARα agonist into the hypothalamus increased PPARα target genes and normalized food intake. Inactivation of β cell FAS enzyme activity had no effect on islet function in culture or in vivo. These results suggest a critical role for brain FAS in the regulation of not only feeding, but also physical activity, effects that appear to be mediated through the provision of ligands generated by FAS to PPARα. Thus, 2 diametrically opposed proteins, FAS (induced by feeding) and PPARα (induced by starvation), unexpectedly form an integrative sensory module in the central nervous system to orchestrate energy balance. Nonstandard abbreviations used: ACO, acyl-CoA oxidase; AgRP, agouti-related protein; CART, cocaine-amphetamine-related transcript; CPT-1, carnitine palmitoyltransferase-1; FAS, fatty acid synthase; FASKO mice, mice lacking FAS in pancreatic β cells and a diffuse neuronal population within the hypothalamus; Glut2, glucose transporter 2; MCD, malonyl-CoA decarboxylase; MCH, melanin-concentrating hormone; NPY, neuropeptide Y; Pdx-1, pancreatic duodenal homeobox-1; POMC, proopiomelanocortin; RIPCre mice, mice expressing Cre under the control of the rat insulin 2 promoter.

PLOS Genetics, 2007

Peroxisome proliferator activated receptor gamma 2 (PPARg2) is the nutritionally regulated isofor... more Peroxisome proliferator activated receptor gamma 2 (PPARg2) is the nutritionally regulated isoform of PPARg. Ablation of PPARg2 in the ob/ob background, PPARg2 À/À Lep ob /Lep ob (POKO mouse), resulted in decreased fat mass, severe insulin resistance, b-cell failure, and dyslipidaemia. Our results indicate that the PPARg2 isoform plays an important role, mediating adipose tissue expansion in response to positive energy balance. Lipidomic analyses suggest that PPARg2 plays an important antilipotoxic role when induced ectopically in liver and muscle by facilitating deposition of fat as relatively harmless triacylglycerol species and thus preventing accumulation of reactive lipid species. Our data also indicate that PPARg2 may be required for the b-cell hypertrophic adaptive response to insulin resistance. In summary, the PPARg2 isoform prevents lipotoxicity by (a) promoting adipose tissue expansion, (b) increasing the lipid-buffering capacity of peripheral organs, and (c) facilitating the adaptive proliferative response of bcells to insulin resistance.

Trends in Biotechnology, 2008

Diabetes, 2001

Recent studies in murine models suggest that resistin (also called Fizz3 [1]), a novel cysteine-r... more Recent studies in murine models suggest that resistin (also called Fizz3 [1]), a novel cysteine-rich protein secreted by adipocytes, may represent the long-sought link between obesity and insulin resistance (2). Furthermore, peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists appear to inhibit resistin expression in murine adipocytes, providing a possible explanation for the mode of action of this class of insulin sensitizers (2). Using a fluorescent real-time reverse transcriptase-polymerase chain reaction-based assay, we found that resistin mRNA levels in whole adipose tissue samples were increased in morbidly obese humans compared with lean control subjects. However, in freshly isolated human adipocytes, resistin mRNA levels were very low and showed no correlation with BMI. Resistin mRNA was undetectable in preadipocytes, endothelial cells, and vascular smooth muscle cells, but it was readily detectable in circulating mononuclear cells. Although exposure of human mononuclear cells to PPAR-gamma agonists markedly upregulated fatty acid-binding protein-4 expression, these agents had no effect on mononuclear cell resistin expression. Finally, resistin mRNA was undetectable in adipocytes from a severely insulin-resistant subject with a dominant-negative mutation in PPAR-gamma (3). We conclude that the recently described relationships of murine resistin/Fizz3 expression with obesity, insulin resistance, and PPAR-gamma action may not readily translate to humans. Further studies of this novel class of proteins are needed to clarify their roles in human metabolism.

Biochemical and Biophysical Research Communications, 1997

in rodents (6-8). However, UCP1 may be of lesser im-Uncoupling proteins (UCPs) are inner mitochon... more in rodents (6-8). However, UCP1 may be of lesser im-Uncoupling proteins (UCPs) are inner mitochonportance in humans in whom the mass of brown adidrial membrane transporters which dissipate the propose tissue is limited. A second uncoupling protein, ton gradient, releasing stored energy as heat. UCP1 is termed UCP2 (9) or UCPH (10) was recently identified. expressed exclusively in brown adipocytes while UCP2 In contrast to UCP1, UCP2 is expressed in many tisis expressed widely. We now report the molecular clonsues, including sites not thought to mediate adaptive ing of a third uncoupling protein homologue, desigthermogenesis. We now report the molecular cloning nated UCP3. At the amino acid level, hUCP3 is 71% of a third uncoupling protein homologue, designated identical to hUCP2 and 57% identical to hUCP1. UCP3 UCP3, which is distinguished from UCP1 and UCP2 is distinguished from UCP1 and UCP2 by its abundant by its preferential expression in skeletal muscle and and preferential expression in skeletal muscle in hubrown adipose tissue, two important sites for regulated mans, and brown adipose tissue and skeletal muscle

Biochemical Journal, 2008

Leak of protons into the mitochondrial matrix during substrate oxidation partially uncouples elec... more Leak of protons into the mitochondrial matrix during substrate oxidation partially uncouples electron transport from phosphorylation of ADP, but the functions and source of basal and inducible proton leak in vivo remain controversial. In the present study we describe an endogenous activation of proton conductance in mitochondria isolated from rat and mouse skeletal muscle following addition of respiratory substrate. This endogenous activation increased with time, required a high membrane potential and was diminished by high concentrations of serum albumin. Inhibition of this endogenous activation by GDP [classically considered specific for UCPs (uncoupling proteins)], carboxyatractylate and bongkrekate (considered specific for the adenine nucleotide translocase) was examined in skeletal muscle mitochondria from wild-type and Ucp3-knockout mice. Proton conductance through endogenously activated UCP3 was calculated as the difference in leak between mitochondria from wild-type and Ucp3-knockout mice, and was found to be inhibited by carboxyatractylate and bongkrekate, but not GDP. Proton conductance in mitochondria from Ucp3-knockout mice was strongly inhibited by carboxyatractylate, bongkrekate and partially by GDP. We conclude the following: (i) at high protonmotive force, an endogenously generated activator stimulates proton conductance catalysed partly by UCP3 and partly by the adenine nucleotide translocase; (ii) GDP is not a specific inhibitor of UCP3, but also inhibits proton translocation by the adenine nucleotide translocase; and (iii) the inhibition of UCP3 by carboxyatractylate and bongkrekate is likely to be indirect, acting through the adenine nucleotide translocase.

Trends in Molecular Medicine, 2005

Human obesity-related diabetes and the accompanying metabolic disorders have been specifically li... more Human obesity-related diabetes and the accompanying metabolic disorders have been specifically linked to increased visceral adipose tissue mass. Understanding the differences in biology of the two human fat depots (visceral and subcutaneous) might hold the key to therapeutic strategies aimed at reducing obesityinduced insulin resistance and alleviating symptoms of the metabolic syndrome. Visfatin (pre-B-cell colonyenhancing factor, PBEF) is a novel adipokine that appears to be preferentially produced by visceral adipose tissue and has insulin-mimetic actions. Could this molecule hold the key to future treatments for type 1 and 2 diabetes? This article discusses the pros and cons of visfatin action and how it might affect future therapeutic strategies.

PLoS Biology, 2011

Diabetes, 2005

Nature medicine, 2010

PloS one, 2012

Diabetes, Aug 6, 2013

Biochemical and Biophysical Research Communications, 2002

Biochemical and Biophysical Research Communications, 1999

Journal of Biological Chemistry, 2000

Expert Review of Molecular Diagnostics, 2006

BMC Systems Biology, 2007

Proceedings of The National Academy of Sciences, 2004

Journal of Clinical Investigation, 2007

PLOS Genetics, 2007

Trends in Biotechnology, 2008

Diabetes, 2001

Biochemical and Biophysical Research Communications, 1997

Biochemical Journal, 2008

Trends in Molecular Medicine, 2005

Genome / National Research Council Canada = Génome / Conseil national de recherches Canada, 2010

Many genes express multiple transcript isoforms generated by alternative splicing of mRNA. Using ... more Many genes express multiple transcript isoforms generated by alternative splicing of mRNA. Using real-time PCR, it is straightforward to determine the relative expression level of each isoform independently. However, it is less trivial to determine the relative proportions of different isoforms in a cDNA sample. The relative proportions of different isoforms can be important, as a small change in a highly abundant transcript may be more relevant than a large change in a minimally expressed transcript. Currently, determining the relative proportions of isoforms requires the construction of a standard curve using recombinant plasmid DNA or genomic DNA. As recombinant or genomic DNA standards often amplify with different efficiencies to cDNA samples, they may give under- or overestimations of isoform abundances. The method described in this article uses a titration curve generated from the same cDNA samples measured in the experiment. By using samples with different levels of separate isoforms, it is possible to derive linear equations which, when solved, allow the determination of the proportion of each isoform within the samples under study.

Molecular and cellular biology, 2004

The putative transcriptional corepressor ETO/MTG8 has been extensively studied due to its involve... more The putative transcriptional corepressor ETO/MTG8 has been extensively studied due to its involvement in a chromosomal translocation causing the t(8;21) form of acute myeloid leukemia. Despite this, the role of ETO in normal physiology has remained obscure. Here we show that ETO is highly expressed in preadipocytes and acts as an inhibitor of C/EBP␤ during early adipogenesis, contributing to its characteristically delayed activation. ETO prevents both the transcriptional activation of the C/EBP␣ promoter by C/EBP␤ and its concurrent accumulation in centromeric sites during early adipogenesis. ETO expression rapidly reduces after the initiation of adipogenesis, and this is essential to the normal induction of adipogenic gene expression. These findings define, for the first time, a molecular role for ETO in normal physiology as an inhibitor of C/EBP␤ and a novel regulator of early adipogenesis.

Biochemical …, Jan 1, 2003