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Fiona McMurray,
Chris D Church,
Rachel Larder,
George Nicholson,
Sara Wells,
Lydia Teboul, Y C Loraine Tung,
Debra Rimmington,
Fatima Bosch,
Veronica Jimenez,
Giles S H Yeo,
Stephen O'Rahilly,
Frances M Ashcroft,
Anthony P Coll,
Roger D Cox
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ABSTRACT: The strongest BMI-associated GWAS locus in humans is the FTO gene. Rodent studies demonstrate a role for FTO in energy homeostasis and body composition. The phenotypes observed in loss of expression studies are complex with perinatal lethality, stunted growth from weaning, and significant alterations in body composition. Thus understanding how and where Fto regulates food intake, energy expenditure, and body composition is a challenge. To address this we generated a series of mice with distinct temporal and spatial loss of Fto expression. Global germline loss of Fto resulted in high perinatal lethality and a reduction in body length, fat mass, and lean mass. When ratio corrected for lean mass, mice had a significant increase in energy expenditure, but more appropriate multiple linear regression normalisation showed no difference in energy expenditure. Global deletion of Fto after the in utero and perinatal period, at 6 weeks of age, removed the high lethality of germline loss. However, there was a reduction in weight by 9 weeks, primarily as loss of lean mass. Over the subsequent 10 weeks, weight converged, driven by an increase in fat mass. There was a switch to a lower RER with no overall change in food intake or energy expenditure. To test if the phenotype can be explained by loss of Fto in the mediobasal hypothalamus, we sterotactically injected adeno-associated viral vectors encoding Cre recombinase to cause regional deletion. We observed a small reduction in food intake and weight gain with no effect on energy expenditure or body composition. Thus, although hypothalamic Fto can impact feeding, the effect of loss of Fto on body composition is brought about by its actions at sites elsewhere. Our data suggest that Fto may have a critical role in the control of lean mass, independent of its effect on food intake.
PLoS Genetics 01/2013; 9(1):e1003166. · 8.69 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: An understanding of the mechanisms underlying body-weight regulation is crucial to tackle the growing problem of obesity. Recent technological advances in the analysis of genetic variation have given novel insights into the molecular basis of common disease. In particular, genomic variants in the fat mass and obesity-associated (FTO) gene have been consistently associated with human adiposity and metabolic disorders. Studies of the product of this previously mysterious gene have formed a vanguard in the quest to turn statistical association into hard biology. In this review, we examine data from human genetic and murine studies that explore the potential role of FTO, a member of the Fe(II)- and 2-oxoglutarate-dependent oxygenase superfamily, in the regulation of energy homeostasis and metabolism.
Trends in Endocrinology and Metabolism 02/2011; 22(2):53-9. · 8.11 Impact Factor
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Isabel Huang-Doran,
Louise S Bicknell,
Francis M Finucane,
Nuno Rocha,
Keith M Porter, Y C Loraine Tung,
Ferenc Szekeres,
Anna Krook,
John J Nolan,
Mark O'Driscoll,
Michael Bober,
Stephen O'Rahilly,
Andrew P Jackson,
Robert K Semple
[show abstract]
[hide abstract]
ABSTRACT: Genetic defects in human pericentrin (PCNT), encoding the centrosomal protein pericentrin, cause a form of osteodysplastic primordial dwarfism that is sometimes reported to be associated with diabetes. We thus set out to determine the prevalence of diabetes and insulin resistance among patients with PCNT defects and examined the effects of pericentrin depletion on insulin action using 3T3-L1 adipocytes as a model system.
A cross-sectional metabolic assessment of 21 patients with PCNT mutations was undertaken. Pericentrin expression in human tissues was profiled using quantitative real-time PCR. The effect of pericentrin knockdown on insulin action and adipogenesis in 3T3-L1 adipocytes was determined using Oil red O staining, gene-expression analysis, immunoblotting, and glucose uptake assays. Pericentrin expression and localization also was determined in skeletal muscle.
Of 21 patients with genetic defects in PCNT, 18 had insulin resistance, which was severe in the majority of subjects. Ten subjects had confirmed diabetes (mean age of onset 15 years [range 5-28]), and 13 had metabolic dyslipidemia. All patients without insulin resistance were younger than 4 years old. Knockdown of pericentrin in adipocytes had no effect on proximal insulin signaling but produced a twofold impairment in insulin-stimulated glucose uptake, approximately commensurate with an associated defect in cell proliferation and adipogenesis. Pericentrin was highly expressed in human skeletal muscle, where it showed a perinuclear distribution.
Severe insulin resistance and premature diabetes are common features of PCNT deficiency but are not congenital. Partial failure of adipocyte differentiation may contribute to this, but pericentrin deficiency does not impair proximal insulin action in adipocytes.
Diabetes 01/2011; 60(3):925-35. · 8.29 Impact Factor
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M P Corander,
B G Challis,
E L Thompson,
Z Jovanovic, Y C Loraine Tung,
D Rimmington,
I T Huhtaniemi,
K G Murphy,
A K Topaloglu,
G S H Yeo,
S O'Rahilly,
W S Dhillo,
R K Semple,
A P Coll
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ABSTRACT: Growing evidence suggests the tachykinin neurokinin B (NKB) may modulate gonadotrophin secretion and play a role in sex-steroid feedback within the reproductive axis. NKB signalling has recently been identified as being necessary for normal human reproductive function, although the precise mechanisms underpinning this role remain to be established. We have used rodents to explore further the role of NKB within the reproductive axis. In particular, we have studied its interactions with kisspeptin, a neuropeptide essential for reproductive function in rodent and human with close anatomical links to NKB within the hypothalamus. Intraperitoneal administration of NKB (50 nmol) to male mice had no effect on circulating luteinsing hormone (LH) levels and, although i.p. kisspeptin (15 nmol) increased LH five-fold, co-administration of NKB and kisspeptin was indistinguishable from kisspeptin alone. Intracerebroventricular administration of NKB (10 nmol) to male mice also had no effect on LH levels, with 1 nmol kisspeptin i.c.v. significantly increasing LH compared to control (0.37 +/- 0.18 versus 5.11 +/- 0.28 ng/ml, respectively). Interestingly, i.c.v. co-administration of NKB and kisspeptin caused a significant increase in LH concentrations compared to kisspeptin alone (8.96 +/- 1.82 versus 5.11 +/- 0.28 ng/ml respectively). We used hypothalamic explants from rats to assess the effect of NKB on gonadotrpohin-releasing hormone (GnRH) secretion ex vivo. Doses of NKB up to 1000 nm failed to stimulate GnRH secretion, whereas 100 nm kisspeptin robustly increased GnRH secretion. Of note, co-administration of NKB with kisspeptin abrogated the effect of kisspeptin, producing no GnRH release above basal state. Finally, we analysed the expression of Tac2/Tacr3 (genes encoding NKB and NK3R, respectively) within the arcuate nucleus in different nutritional states. After a 48-h fast, the expression of both Tac2 and Tacr3 showed a significant increase, in contrast to levels of Kiss1 and Kiss1r mRNA, which remained unchanged. In male rodent models, NKB and kisspeptin have different effects upon gonadotrophin release and appear to interact in a complex manner.
Journal of Neuroendocrinology 03/2010; 22(3):181-7. · 3.14 Impact Factor
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Satya Dash,
Hiroyuki Sano,
Justin J Rochford,
Robert K Semple,
Giles Yeo,
Caroline S S Hyden,
Maria A Soos,
James Clark,
Andrew Rodin,
Claudia Langenberg,
Celine Druet,
Katherine A Fawcett, Y C Loraine Tung,
Nicolas J Wareham,
Inês Barroso,
Gustav E Lienhard,
Stephen O'Rahilly,
David B Savage
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ABSTRACT: Tre-2, BUB2, CDC16, 1 domain family member 4 (TBC1D4) (AS160) is a Rab-GTPase activating protein implicated in insulin-stimulated glucose transporter 4 (GLUT4) translocation in adipocytes and myotubes. To determine whether loss-of-function mutations in TBC1D4 might impair GLUT4 translocation and cause insulin resistance in humans, we screened the coding regions of this gene in 156 severely insulin-resistant patients. A female presenting at age 11 years with acanthosis nigricans and extreme postprandial hyperinsulinemia was heterozygous for a premature stop mutation (R363X) in TBC1D4. After demonstrating reduced expression of wild-type TBC1D4 protein and expression of the truncated protein in lymphocytes from the proband, we further characterized the biological effects of the truncated protein in 3T3L1 adipocytes. Prematurely truncated TBC1D4 protein tended to increase basal cell membrane GLUT4 levels (P = 0.053) and significantly reduced insulin-stimulated GLUT4 cell membrane translocation (P < 0.05). When coexpressed with wild-type TBC1D4, the truncated protein dimerized with full-length TBC1D4, suggesting that the heterozygous truncated variant might interfere with its wild-type counterpart in a dominant negative fashion. Two overweight family members with the mutation also manifested normal fasting glucose and insulin levels but disproportionately elevated insulin levels following an oral glucose challenge. This family provides unique genetic evidence of TBC1D4 involvement in human insulin action.
Proceedings of the National Academy of Sciences 06/2009; 106(23):9350-5. · 9.68 Impact Factor
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Cristen J Willer,
Elizabeth K Speliotes,
Ruth J F Loos,
Shengxu Li,
Cecilia M Lindgren,
Iris M Heid,
Sonja I Berndt,
Amanda L Elliott,
Anne U Jackson,
Claudia Lamina, [......],
Karen L Mohlke,
Leena Peltonen,
David Schlessinger,
David P Strachan,
H-Erich Wichmann,
Mark I McCarthy,
Michael Boehnke,
Inês Barroso,
Gonçalo R Abecasis,
Joel N Hirschhorn
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ABSTRACT: Common variants at only two loci, FTO and MC4R, have been reproducibly associated with body mass index (BMI) in humans. To identify additional loci, we conducted meta-analysis of 15 genome-wide association studies for BMI (n > 32,000) and followed up top signals in 14 additional cohorts (n > 59,000). We strongly confirm FTO and MC4R and identify six additional loci (P < 5 x 10(-8)): TMEM18, KCTD15, GNPDA2, SH2B1, MTCH2 and NEGR1 (where a 45-kb deletion polymorphism is a candidate causal variant). Several of the likely causal genes are highly expressed or known to act in the central nervous system (CNS), emphasizing, as in rare monogenic forms of obesity, the role of the CNS in predisposition to obesity.
Nature Genetics 12/2008; 41(1):25-34. · 35.53 Impact Factor
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ABSTRACT: The metabolic effects of leptin may involve both centrally and peripherally mediated actions with a component of the central actions potentially independent of alterations in food intake. Ob/ob mice have significant abnormalities in lipid metabolism, correctable by leptin administration. We used ob/ob mice to study the relative importance of the subtypes of actions of leptin (central vs. peripheral; food intake dependent vs. independent) on lipid metabolism. Mice were treated for 3 d with leptin, either centrally [intracerebroventricular (icv)] or peripherally (ip), and compared with mice pair-fed to the leptin-treated mice (PF) and with ad libitum-fed controls (C). All treatment groups (icv, ip, PF) showed indistinguishable changes in liver weight; hepatic steatosis; hepatic lipidemic profile; and circulating free fatty acids, triglycerides, and cholesterol lipoprotein profile. Changes in the expression of genes involved in lipogenesis and fatty acid oxidation in liver, muscle, and white fat were broadly similar in ip, icv, and PF groups. Leptin (both icv and ip) stimulated expression of both mitochondrial and peroxisomal acyl-coenzyme A oxidase (liver) and peroxisomal proliferator-activated receptor-alpha (skeletal muscle) to an extent not replicated by pair feeding. Leptin had profound effects on peripheral lipid metabolism, but the majority were explained by its effects on food intake. Leptin had additional centrally mediated effects to increase the expression of a limited number of genes concerned with fatty acid oxidation. Whereas we cannot exclude direct peripheral effects of leptin on certain aspects of lipid metabolism, we were unable to detect any such effects on the parameters measured in this study.
Endocrinology 11/2008; 149(11):5432-9. · 4.46 Impact Factor
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[show abstract]
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ABSTRACT: Human genetic data indicate impaired synthesis or processing of POMC results in obesity. We have used a mouse model of POMC deficiency (Pomc null) to explore the role of POMC-derived peptides in energy homeostasis. The phenotype of Pomc null mice recapitulates the clinical syndrome seen in humans congenitally lacking POMC. Loss of only one copy of the Pomc gene is sufficient to render mice susceptible to the effects of high fat feeding, emphasizing an important gene-environment interaction predisposing to obesity. Our studies indicate that POMC-derived peptides have influences on the response to a high fat diet, including a major influence on the dietary preference for fat. Pomc null mice are unusual in that obesity and hyperphagia develop in the absence of circulating glucocorticoid (GC). To investigate the interaction between GCs and the melanocortin system, we administered corticosterone to Pomc null mice. They appear hypersensitive to the adverse metabolic effects of GCs, developing hypertension, an exacerbation of both hyperphagia and obesity and a profound insulin resistance. GC treatment of Pomc null mice significantly increases the expression of the melanocortin antagonist agouti-related protein (AgRP). On-going studies in mice lacking both AgRP and Pomc will determine whether the metabolic phenotype seen with this GC therapy is due to a lack of melanocortin peptide, the unopposed action of AgRP or a combination of both.
Molecular and Cellular Endocrinology 10/2008; 300(1-2):147-51. · 4.19 Impact Factor
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ABSTRACT: Complete proopiomelanocortin (POMC) deficiency causes a human syndrome of hypoadrenalism, altered skin and hair pigmentation, and severe hyperphagic obesity. Heterozygote carriers of nonsense mutations are strongly predisposed to obesity. Pomc(+/-) mice have normal body weight on a chow diet but increase food intake and become more obese than wild-type littermates when placed on a high-fat diet. To further explore the mechanisms whereby dietary fat interacts with Pomc genotype to produce obesity, we examined Pomc-null, Pomc(+/-), and wild-type mice for changes in the components of energy balance in response to provision of a high-fat diet and macronutrient preference when presented with a selection of dietary choices. In contrast to wild-type mice, Pomc null mice did not increase their resting energy expenditure or their spontaneous physical activity when given a high-fat diet. Pomc(+/-) mice increased resting energy expenditure similarly to wild types, but their increase in physical activity was significantly less than that seen in wild-type mice. In two independent experimental tests of macronutrient preference, Pomc genotype was a strong predictor of dietary fat preference with Pomc null animals choosing to eat approximately twice as much fat, but similar amounts of carbohydrate and protein, as wild-type animals. Pomc(+/-) mice showed an intermediate response. In summary, POMC-derived peptides have influences on multiple aspects of the organism's response to the presentation of high-fat diet. This includes a major influence, readily discernible even in heterozygote animals, on the dietary preference for fat.
Endocrinology 12/2007; 148(11):5331-8. · 4.46 Impact Factor
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[show abstract]
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ABSTRACT: Functional disruption of either MC3R or MC4R results in obesity, implicating both in the control of energy homeostasis. The ligands for these receptors are derived from the prohormone proopiomelancortin (POMC), which is posttranslationally processed to produce a set of melanocortin peptides with a range of activities at the MC3R and MC4R. The relative importance of each of these peptides alpha-MSH, gamma3-MSH, gamma2-MSH, gamma-lipotropin (gamma-LPH) and, in man but not in rodents, beta-MSH] in the maintenance of energy homeostasis is, as yet, unclear. To investigate this further, equimolar amounts (2 nmol) of each peptide were centrally administered to freely feeding, corticosterone-supplemented, Pomc null (Pomc-/-) mice. After a single dose at the onset of the dark cycle, alpha-MSH had the most potent anorexigenic effect, reducing food intake to 35% of sham-treated animals. beta-MSH, gamma-LPH, and gamma3- and gamma2-MSH all reduced food intake but to a lesser degree. The effects of peptide administration over 3 d were also assessed. Only alpha-MSH significantly reduced body weight, affecting both fat and lean mass. Other peptides had no significant effect on body weight. Pair-feeding of sham-treated mice to those treated with alpha-MSH resulted in identical changes in total weight, fat and lean mass indicating that the effects of alpha-MSH were primarily due to reduced food intake rather than increased energy expenditure. Although other melanocortins can reduce food intake in the short-term, only alpha-MSH can reduce the excess fat and lean mass found in Pomc-/- mice, mediated largely through an effect on food intake.
Endocrinology 01/2007; 147(12):5940-7. · 4.46 Impact Factor
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Juliette Gray,
Giles S H Yeo,
James J Cox,
Jenny Morton,
Anna-Lynne R Adlam,
Julia M Keogh,
Jack A Yanovski,
Areeg El Gharbawy,
Joan C Han, Y C Loraine Tung,
John R Hodges,
F Lucy Raymond,
Stephen O'rahilly,
I Sadaf Farooqi
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ABSTRACT: The neurotrophin brain-derived neurotrophic factor (BDNF) inhibits food intake, and rodent models of BDNF disruption all exhibit increased food intake and obesity, as well as hyperactivity. We report an 8-year-old girl with hyperphagia and severe obesity, impaired cognitive function, and hyperactivity who harbored a de novo chromosomal inversion, 46,XX,inv(11)(p13p15.3), a region encompassing the BDNF gene. We have identified the proximal inversion breakpoint that lies 850 kb telomeric of the 5' end of the BDNF gene. The patient's genomic DNA was heterozygous for a common coding polymorphism in BDNF, but monoallelic expression was seen in peripheral lymphocytes. Serum concentration of BDNF protein was reduced compared with age- and BMI-matched subjects. Haploinsufficiency for BDNF was associated with increased ad libitum food intake, severe early-onset obesity, hyperactivity, and cognitive impairment. These findings provide direct evidence for the role of the neurotrophin BDNF in human energy homeostasis, as well as in cognitive function, memory, and behavior.
Diabetes 01/2007; 55(12):3366-71. · 8.29 Impact Factor
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Anthony P Coll,
Martin Fassnacht,
Steffen Klammer,
Stephanie Hahner,
Dominik M Schulte,
Sarah Piper, Y C Loraine Tung,
Benjamin G Challis,
Yacob Weinstein,
Bruno Allolio,
Stephen O'Rahilly,
Felix Beuschlein
[show abstract]
[hide abstract]
ABSTRACT: Pro-opiomelanocortin (POMC) is a polypeptide precursor that undergoes extensive processing to yield a range of peptides with biologically diverse functions. POMC-derived ACTH is vital for normal adrenal function and the melanocortin alpha-MSH plays a key role in appetite control and energy homeostasis. However, the roles of peptide fragments derived from the highly conserved N-terminal region of POMC are less well characterized. We have used mice with a null mutation in the Pomc gene (Pomc(-/-)) to determine the in vivo effects of synthetic N-terminal 1-28 POMC, which has been shown previously to possess adrenal mitogenic activity. 1-28 POMC (20 mug) given s.c. for 10 days had no effect on the adrenal cortex of Pomc(-/-) mice, with resultant cortical morphology and plasma corticosterone levels being indistinguishable from sham treatment. Concurrent administration of 1-28 POMC and 1-24 ACTH (30 mug/day) resulted in changes identical to 1-24 ACTH treatment alone, which consisted of upregulation of steroidogenic enzymes, elevation of corticosterone levels, hypertrophy of the zona fasciculate, and regression of the X-zone. However, treatment of corticosterone-depleted Pomc(-/-) mice with 1-28 POMC reduced cumulative food intake and total body weight. These anorexigenic effects were ameliorated when the peptide was administered to Pomc(-/-) mice with circulating corticosterone restored either to a low physiological level by corticosterone-supplemented drinking water (CORT) or to a supraphysiological level by concurrent 1-24 ACTH administration. Further, i.c.v. administration of 1-28 POMC to CORT-treated Pomc(-/-) mice had no effect on food intake or body weight. In wild-type mice, the effects of 1-28 POMC upon food intake and body weight were identical to sham treatment, but 1-28 POMC was able to ameliorate the hyperphagia induced by concurrent 1-24 ACTH treatment. In a mouse model which lacks all endogenous POMC peptides, s.c. treatment with synthetic 1-28 POMC alone can reduce food intake and body weight, but has no impact upon adrenal growth or steroidogenesis.
Journal of Endocrinology 09/2006; 190(2):515-25. · 3.55 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Human genetic data indicate impaired synthesis or processing of POMC results in obesity. We have used a mouse model of POMC deficiency (Pomc null) to explore the role of POMC-derived peptides in energy homeostasis. The phenotype of Pomc null mice recapitulates the clinical syndrome seen in humans congenitally lacking POMC. Loss of only one copy of the Pomc gene is sufficient to render mice susceptible to the effects of high fat feeding, emphasizing an important gene–environment interaction predisposing to obesity. Our studies indicate that POMC-derived peptides have influences on the response to a high fat diet, including a major influence on the dietary preference for fat. Pomc null mice are unusual in that obesity and hyperphagia develop in the absence of circulating glucocorticoid (GC). To investigate the interaction between GCs and the melanocortin system, we administered corticosterone to Pomc null mice. They appear hypersensitive to the adverse metabolic effects of GCs, developing hypertension, an exacerbation of both hyperphagia and obesity and a profound insulin resistance. GC treatment of Pomc null mice significantly increases the expression of the melanocortin antagonist agouti-related protein (AgRP). On-going studies in mice lacking both AgRP and Pomc will determine whether the metabolic phenotype seen with this GC therapy is due to a lack of melanocortin peptide, the unopposed action of AgRP or a combination of both.
Molecular and Cellular Endocrinology.
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[show abstract]
[hide abstract]
ABSTRACT: An understanding of the mechanisms underlying body-weight regulation is crucial to tackle the growing problem of obesity. Recent technological advances in the analysis of genetic variation have given novel insights into the molecular basis of common disease. In particular, genomic variants in the fat mass and obesity-associated (FTO) gene have been consistently associated with human adiposity and metabolic disorders. Studies of the product of this previously mysterious gene have formed a vanguard in the quest to turn statistical association into hard biology. In this review, we examine data from human genetic and murine studies that explore the potential role of FTO, a member of the Fe(II)- and 2-oxoglutarate-dependent oxygenase superfamily, in the regulation of energy homeostasis and metabolism.
Trends in Endocrinology & Metabolism.
