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ABSTRACT: Adipogenesis is regulated by a coordinated cascade of sequence-specific transcription factors and coregulators with chromatin-modifying activities that are between them responsible for the establishment of the gene expression pattern of mature adipocytes. Here we examine the histone H3 post-translational modifications occurring at the promoters of key adipogenic genes during adipocyte differentiation. We show that the promoters of apM1, glut4, gpd1, and leptin are enriched in dimethylated histone H3 Lys4 (H3-K4) in 3T3-L1 fibroblasts, where none of these genes are yet expressed. A detailed study of the apM1 locus shows that H3-K4 dimethylation is restricted to the promoter region in undifferentiated cells and associates with RNA polymerase II (pol II) loading. The beginning of apM1 transcription at the early stages of adipogenesis coincides with promoter H3 hyperacetylation and H3-K4 trimethylation. At the coding region, H3 acetylation and dimethylation, as well as pol II binding, are found in cells at later stages of differentiation, when apM1 transcription reaches its maximal peak. This same pattern of histone modifications is detected in mouse primary preadipocytes and adipocytes but not in a related fibroblast cell line that is not committed to an adipocyte fate. Inhibition of H3-K4 methylation by treatment of 3T3-L1 cells with methylthioadenosine results in decreased apM1 gene expression as well as decreased adipogenesis. Taken together, our data indicate that H3-K4 dimethylation and pol II binding to the promoter of key adipogenic genes are distinguishing marks of cells that have undergone determination to a preadipocyte stage.
Journal of Biological Chemistry 07/2006; 281(25):17180-8. · 4.77 Impact Factor
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ABSTRACT: The effects of adiponectin on glucose and lipid metabolism are mediated by the adiponectin receptors, adipoR1 and adipoR2, which are mainly in liver and muscle. We investigated the presence of adiponectin receptors in intra-abdominal adipose tissue (IAAT) in obesity and diabetes and their association with adiponectin expression and components of the metabolic syndrome and/or other metabolic factors associated with atherosclerotic cardiovascular disease (ASCVD).
AdipoR1 and adipoR2 gene expression was measured by quantitative real time reverse transcription polymerase chain reaction in IAAT from lean and obese patients with or without diabetes type 2. Correlation between metabolic characteristics of obese patients and expression of these receptors was studied.
Neither obesity nor diabetes were associated with changes in IAAT-adipoR1 expression. In contrast, IAAT-adipoR2 was decreased by 39.5% in obese non-diabetics and by 52.7% in obese diabetics when compared to lean subjects. AdipoR1 and adiponectin expression was associated in lean (r=0.943, P<0.005) and obese non-diabetic patients (r=0.74, P<0.01), whereas a positive correlation between adipoR2 and adiponectin expression was only found in the presence of diabetes (r=0.883, P<0.002). AdipoR1 expression was associated with plasma free fatty acids (FFA) concentration (r=0.76, P<0.04), and adipoR2 inversely correlated with plasma levels of triglycerides (r=-0.76, P<0.04) and apolipoprotein B (r=-0.74, P<0.05).
AdipoR1 expression in IAAT was not altered by obesity and/or diabetes and was related to plasma levels of FFA. IAAT-adipoR2 expression was reduced in obesity and diabetes and associated with components of metabolic processes leading to cardiovascular disease in obesity.
Obesity Surgery 06/2006; 16(6):745-51. · 3.29 Impact Factor
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ABSTRACT: One of the main pathological characteristics of Alzheimer's disease is the presence in the brain of the patients of an aberrant structure, the paired helical filaments, composed of hyperphosphorylated tau. The level of tau phosphorylation has been correlated with the capacity for tau aggregation. Thus, the mechanism for tau phosphorylation could be important to clarify those pathological features in Alzheimer's disease. Tau protein could be modified by different kinases, being GSK3 the one that could modify more sites of that protein. GSK3 activity could be modulate by the presence of metals like magnesium that can be required for the proper function of the kinase, whereas, metals like manganesum or lithium inhibit the activity of the kinase. Many works have been done to study the inhibition of GSK3 by lithium, a specific inhibitor of that kinase. More recently, it has been indicated that sodium tungstate could also inhibit GSK3 through a different mechanism. In this review, we discuss the effect of these two metals, lithium and tungstate, on GSK3 (or tau I kinase) activity.
Current Alzheimer Research 05/2006; 3(2):123-7. · 3.95 Impact Factor
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ABSTRACT: Tungstate treatment increases the phosphorylation of glycogen synthase kinase-3beta (GSK3beta) at serine 9, which triggers its inactivation both in cultured neural cells and in vivo. GSK3 phosphorylation is dependent on the activation of extracellular signal-regulated kinases 1/2 (ERK1/2) induced by tungstate. As a consequence of GSK3 inactivation, the phosphorylation of several GSK3-dependent sites of the microtubule-associated protein tau decreases. Tungstate reduces tau phosphorylation only in primed sequences, namely, those prephosphorylated by other kinases before GSK3beta modification, which are serines 198, 199, or 202 and threonine 231. The phosphorylation at these sites is involved in reduction of the interaction of tau with microtubules that occurs in Alzheimer's disease.
Journal of Neuroscience Research 03/2006; 83(2):264-73. · 2.74 Impact Factor
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ABSTRACT: Adipose tissue plays an active role in the development of obesity, and thus characterization of the molecular changes related to obesity in this tissue is a priority. Recently, we identified tungstate as a potent body weight reducing agent in obese animals, adipose tissue being one of the targets of its action. In this study a proteomics approach combining 2-DE and MS was used to identify proteins associated with obesity and targets of tungstate in white adipose tissue. Twenty-nine proteins were found differentially expressed between lean and diet-induced obese rats. Expression changes in transferrin, vimentin, vinculin, peroxiredoxins, Rho-GTP dissociation inhibitor, grifin, guanine deaminase and 3-phosphoglycerate dehydrogenase were associated here for the first time with obesity. Furthermore, tungstate treatment of obese rats reverted expression changes of 70% of the proteins modulated by obesity and another ten proteins were regulated by tungstate independently of the body weight reduction. The results suggest that the tungstate antiobesity effect can be mediated by the modulation of cellular structure, metabolism, redox state and signalling processes in adipose tissue. These findings open new avenues for the study of the aetiology of obesity and its treatment.
PROTEOMICS 01/2006; 5(18):4927-35. · 4.51 Impact Factor
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ABSTRACT: The increasing worldwide incidence of obesity and the limitations of current treatments raise the need for finding novel therapeutic approaches to treat this disease. The purpose of the current study was first to investigate the effects of tungstate on body weight and insulin sensitivity in a rat model of diet-induced obesity. Second, we aimed to gain insight into the molecular mechanisms underlying its action. Oral administration of tungstate significantly decreased body weight gain and adiposity without modifying caloric intake, intestinal fat absorption, or growth rate in obese rats. Moreover, the treatment ameliorated dislipemia and insulin resistance of obese rats. These effects were mediated by an increase in whole-body energy dissipation and by changes in the expression of genes involved in the oxidation of fatty acids and mitochondrial uncoupling in adipose tissue. Furthermore, treatment increased the number of small adipocytes with a concomitant induction of apoptosis. Our results indicate that tungstate treatment may provide the basis for a promising novel therapy for obesity.
Endocrinology 11/2005; 146(10):4362-9. · 4.46 Impact Factor
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Marc Claret, Helena Corominola,
Ignasi Canals,
Belén Nadal,
Alain Chavanieu,
Bruno Pfeiffer,
Pierre Renard,
Carmen Gorostiaga,
Philippe Delagrange,
Gérard Grassy,
Ramon Gomis
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ABSTRACT: To investigate the effect of S 23521, a new glucagon-like peptide-1-(7-36) amide analogue, on food intake and body weight gain in obese rats, as well as on gene expression of several proteins involved in energy homeostasis.
Lean and diet-induced obese rats were treated with either S 23521 or vehicle. S 23521 was given either intraperitoneally (10 or 100 microg/kg) or subcutaneously (100 microg/kg) for 14 and 20 days, respectively. Because the low-dose treatment did not affect food intake and body weight, the subcutaneous treatment at high dose was selected to test the effect on selected end-points.
Treated obese rats significantly decreased their cumulative energy intake in relation to vehicle-treated counterparts (3401 +/- 65 vs. 3898 +/- 72 kcal/kg per 20 days; p < 0.05). Moreover, their body weight gain was reduced by 110%, adiposity was reduced by 20%, and plasma triglyceride levels were reduced by 38%. The treatment also improved glucose tolerance and insulin sensitivity of obese rats. Regarding gene expression, no changes in uncoupling protein-1, uncoupling protein-3, leptin, resistin, and peroxisome proliferator-activated receptor (PPAR)-gamma were observed.
S 23521 is an effective glucagon-like peptide-1-(7-36) amide analogue, which induced a decrease in energy intake, body weight, and adiposity in a rat model of diet-induced obesity. In addition, the treatment also improved glucose tolerance and insulin sensitivity of obese rats. These results strongly support S 23521 as a putative molecule for the treatment of obesity.
Obesity research 10/2004; 12(10):1596-603. · 4.95 Impact Factor
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Marc Claret, Helena Corominola,
Ignasi Canals,
Bel|[eacute]|n Nadal,
Alain Chavanieu,
Bruno Pfeiffer,
Pierre Renard,
Carmen Gorostiaga,
Philippe Delagrange,
G|[eacute]|rard Grassy,
Ramon Gomis
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ABSTRACT: Objective: To investigate the effect of S 23521, a new glucagon-like peptide-1-(7-36) amide analogue, on food intake and body weight gain in obese rats, as well as on gene expression of several proteins involved in energy homeostasis.Research Methods and Procedures: Lean and diet-induced obese rats were treated with either S 23521 or vehicle. S 23521 was given either intraperitoneally (10 or 100 g/kg) or subcutaneously (100 g/kg) for 14 and 20 days, respectively. Because the low-dose treatment did not affect food intake and body weight, the subcutaneous treatment at high dose was selected to test the effect on selected end-points.Results: Treated obese rats significantly decreased their cumulative energy intake in relation to vehicle-treated counterparts (3401 65 vs. 3898 72 kcal/kg per 20 days; p < 0.05). Moreover, their body weight gain was reduced by 110%, adiposity was reduced by 20%, and plasma triglyceride levels were reduced by 38%. The treatment also improved glucose tolerance and insulin sensitivity of obese rats. Regarding gene expression, no changes in uncoupling protein-1, uncoupling protein-3, leptin, resistin, and peroxisome proliferator-activated receptor (PPAR)- were observed.Discussion: S 23521 is an effective glucagon-like peptide-1-(7-36) amide analogue, which induced a decrease in energy intake, body weight, and adiposity in a rat model of diet-induced obesity. In addition, the treatment also improved glucose tolerance and insulin sensitivity of obese rats. These results strongly support S 23521 as a putative molecule for the treatment of obesity.Keywords: adiposity, glucose tolerance, insulin sensitivity, gene expression
Obesity 09/2004; 12(10):1596-1603. · 4.28 Impact Factor
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ABSTRACT: In cirrhotic livers, increased resistance to portal flow, in part due to an exaggerated response to vasoconstrictors, is the primary factor in the pathophysiology of portal hypertension. Our aim was to evaluate the response of the intrahepatic circulation of cirrhotic rat livers to the alpha(1)-adrenergic vasoconstrictor methoxamine and the mechanisms involved in its regulation. A portal perfusion pressure dose-response curve to methoxamine was performed in control and cirrhotic rat livers preincubated with vehicle, the nitric oxide synthase blocker N(G)-nitro-L-arginine (L-NNA), indomethacin cyclooxygenase (COX) inhibitor, L-NNA + indomethacin, or the thromboxane (TX) A(2) receptor blocker SQ 29,548. TXA(2) production, COX-1 and COX-2 mRNA expression, and immunostaining for TXA(2) synthase were evaluated. Cirrhotic livers exhibited a hyperresponse to methoxamine associated with overexpression of COX-2 and TXA(2) synthase as well as with increased production of TXA(2). The hyperresponse to methoxamine of cirrhotic livers disappeared by COX inhibition with indomethacin but not after NO inhibition. SQ 29,548 also corrected the hyperresponse of cirrhotic livers to methoxamine. In conclusion, COX-derived prostanoids, mainly TXA(2), play a major role in regulating the response of cirrhotic livers to methoxamine.
Hepatology 02/2003; 37(1):172-81. · 11.66 Impact Factor
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ABSTRACT: In cirrhotic livers, increased resistance to portal flow, in part due to an exaggerated response to vasoconstrictors, is the primary factor in the pathophysiology of portal hypertension. Our aim was to evaluate the response of the intrahepatic circulation of cirrhotic rat livers to the α1-adrenergic vasoconstrictor methoxamine and the mechanisms involved in its regulation. A portal perfusion pressure dose-response curve to methoxamine was performed in control and cirrhotic rat livers preincubated with vehicle, the nitric oxide synthase blocker NG-nitro-L-arginine (L-NNA), indomethacin cyclooxygenase (COX) inhibitor, L-NNA + indomethacin, or the thromboxane (TX) A2 receptor blocker SQ 29,548. TXA2 production, COX-1 and COX-2 mRNA expression, and immunostaining for TXA2 synthase were evaluated. Cirrhotic livers exhibited a hyperresponse to methoxamine associated with overexpression of COX-2 and TXA2 synthase as well as with increased production of TXA2. The hyperresponse to methoxamine of cirrhotic livers disappeared by COX inhibition with indomethacin but not after NO inhibition. SQ 29,548 also corrected the hyperresponse of cirrhotic livers to methoxamine. In conclusion, COX-derived prostanoids, mainly TXA2, play a major role in regulating the response of cirrhotic livers to methoxamine.
Hepatology 12/2002; 37(1):172 - 181. · 11.66 Impact Factor
