p53 in AgRP neurons is required for protection against diet-induced obesity via JNK1.

p53 is a well-known tumor suppressor that has emerged as an important player in energy balance. However, its metabolic role in the hypothalamus remains unknown. Herein, we show that mice lacking p53 in agouti-related peptide (AgRP), but not proopiomelanocortin (POMC) or steroidogenic factor-1 (SF1) neurons, are more prone to develop diet-induced obesity and show reduced brown adipose tissue (BAT) thermogenic activity. AgRP-specific ablation of p53 resulted in increased hypothalamic c-Jun N-terminal kinase (JNK) activity before the mice developed obesity, and central inhibition of JNK reversed the obese phenotype of these mice. The overexpression of p53 in the ARC or specifically in AgRP neurons of obese mice decreased body weight and stimulated BAT thermogenesis, resulting in body weight loss. Finally, p53 in AgRP neurons regulates the ghrelin-induced food intake and body weight. Overall, our findings provide evidence that p53 in AgRP neurons is required for normal adaptations against diet-induced obesity.

Hypothalamic AMPK-ER Stress-JNK1 Axis Mediates the Central Actions of Thyroid Hormones on Energy Balance.

Thyroid hormones (THs) act in the brain to modulate energy balance. We show that central triiodothyronine (T3) regulates de novo lipogenesis in liver and lipid oxidation in brown adipose tissue (BAT) through the parasympathetic (PSNS) and sympathetic nervous system (SNS), respectively. Central T3 promotes hepatic lipogenesis with parallel stimulation of the thermogenic program in BAT. The action of T3 depends on AMP-activated protein kinase (AMPK)-induced regulation of two signaling pathways in the ventromedial nucleus of the hypothalamus (VMH): decreased ceramide-induced endoplasmic reticulum (ER) stress, which promotes BAT thermogenesis, and increased c-Jun N-terminal kinase (JNK) activation, which controls hepatic lipid metabolism. Of note, ablation of AMPKα1 in steroidogenic factor 1 (SF1) neurons of the VMH fully recapitulated the effect of central T3, pointing to this population in mediating the effect of central THs on metabolism. Overall, these findings uncover the underlying pathways through which central T3 modulates peripheral metabolism.

Proteome from patients with metabolic syndrome is regulated by quantity and quality of dietary lipids.

BACKGROUND: Metabolic syndrome is a multi-component disorder associated to a high risk of cardiovascular disease. Its etiology is the result of a complex interaction between genetic and environmental factors, including dietary habits. We aimed to identify the target proteins modulated by the long-term consumption of four diets differing in the quality and quantity of lipids in the whole proteome of peripheral blood mononuclear cells (PBMC). RESULTS: A randomized, controlled trial conducted within the LIPGENE study assigned 24 MetS patients for 12 weeks each to 1 of 4 diets: a) high-saturated fatty acid (HSFA), b) high-monounsaturated fatty acid (HMUFA), c) low-fat, high-complex carbohydrate diets supplemented with placebo (LFHCC) and d) low-fat, high-complex carbohydrate diets supplemented with long chain (LC) n-3 polyunsaturated fatty acids (PUFA) (LFHCC n-3). We analyzed the changes induced in the proteome of both nuclear and cytoplasmic fractions of PBMC using 2-D proteomic analysis. Sixty-seven proteins were differentially expressed after the long-term consumption of the four diets. The HSFA diet induced the expression of proteins responding to oxidative stress, degradation of ubiquitinated proteins and DNA repair. However, HMUFA, LFHCC and LFHCC n-3 diets down-regulated pro-inflammatory and oxidative stress-related proteins and DNA repairing proteins. CONCLUSION: The long-term consumption of HSFA, compared to HMUFA, LFHCC and LFHCC n-3, seems to increase the cardiovascular disease (CVD) risk factors associated with metabolic syndrome, such as inflammation and oxidative stress, and seem lead to DNA damage as a consequence of high oxidative stress.

Effect of frying oils on the postprandial endoplasmic reticulum stress in obese people.

The addition of antioxidants to frying oil reduces postprandial oxidative stress and the inflammatory response. ER stress may trigger both inflammation and oxidative stress processes. We aimed to determine the biological effects of the intake of four models of frying oils on postprandial ER stress in peripheral blood mononuclear cells. Twenty obese people received four breakfasts following a randomized crossover design, consisting of muffins made with different oils (virgin olive oil (VOO), sunflower oil (SFO), and a mixture of seed oils (SFO/canola oil) with either dimethylpolysiloxane (SOD) or natural antioxidants from olives (SOP) added), which were previously subjected to 20 heating cycles. ER stress was assessed by measuring the mRNA levels of sXBP1, BiP, CRT, and CNX in peripheral blood mononuclear cells. Our study showed that the intake of the muffins made with SFO induced the postprandial increase of the mRNA levels of the ER stress-sensor sXBP1, and the ER stress related chaperones BiP and CRT (all p-values <0.05). The harmful effects associated with the use of SFO as frying oil, in terms of inflammatory response and postprandial oxidative stress, may be partially mediated by the induction of postprandial ER stress.

Effect of dietary fat modification on subcutaneous white adipose tissue insulin sensitivity in patients with metabolic syndrome.

SCOPE: To determine whether the insulin resistance that exists in metabolic syndrome (MetS) patients is modulated by dietary fat composition. METHODS AND RESULTS: Seventy-five patients were randomly assigned to one of four diets for 12 wk: high-saturated fatty acids (HSFAs), high-MUFA (HMUFA), and two low-fat, high-complex carbohydrate (LFHCC) diets supplemented with long-chain n-3 (LFHCC n-3) PUFA or placebo. At the end of intervention, the LFHCC n-3 diet reduced plasma insulin, homeostasis model assessment of insulin resistance, and nonsterified fatty acid concentration (p < 0.05) as compared to baseline Spanish habitual (BSH) diet. Subcutaneous white adipose tissue (WAT) analysis revealed decreased EH-domain containing-2 mRNA levels and increased cbl-associated protein gene expression with the LFHCC n-3 compared to HSFA and HMUFA diets, respectively (p < 0.05). Moreover, the LFHCC n-3 decreased gene expression of glyceraldehyde-3-phosphate dehydrogenase with respect to HMUFA and BSH diets (p < 0.05). Finally, proteomic characterization of subcutaneous WAT identified three proteins of glucose metabolism downregulated by the LFHCC n-3 diet, including annexin A2. RT-PCR analysis confirmed the decrease of annexin A2 (p = 0.027) after this diet. CONCLUSION: Our data suggest that the LFHCC n-3 diet reduces systemic insulin resistance and improves insulin signaling in subcutaneous WAT of MetS patients compared to HSFA and BSH diets consumption.

Peripheral blood mononuclear cells as in vivo model for dietary intervention induced systemic oxidative stress.

Our aim was to assess the use of peripheral blood mononuclear cells (PBMC) as an in vivo cellular model to evaluate diet-induced changes in the oxidative stress status by analyzing the gene expression pattern of NADPH-oxidase subunits and antioxidant genes. A randomized, controlled trial assigned metabolic syndrome patients to 4 diets for 12 weeks each: (i) high-saturated fatty acid (HSFA), (ii) high-monounsaturated fatty acid, and (iii), (iv) two low-fat, high-complex carbohydrate diets supplemented with n-3 polyunsaturated fatty acids or placebo. A fat challenge reflecting the fatty acid composition as the original diets was conducted post-intervention. The mRNA levels of gp91(phox) (P<0.001), p22(phox) (P=0.005), p47(phox) (P=0.001) and p40(phox) (P<0.001) increased at 2h after the intake of the HSFA meal. The expression of SOD1, SOD2, GSR, GPx1, GPX4, TXN, TXNRD1 and Nrf2 increased after the HSFA meal (p<0.05). In contrast, the expression of these genes remained unaltered in response to the other dietary interventions. Our results suggest that the increased expression of antioxidant genes in PBMC seems to be due to the response to the postprandial oxidative stress generated mainly in adipose tissue after the consumption of an HSFA diet.

Postprandial activation of p53-dependent DNA repair is modified by Mediterranean diet supplemented with coenzyme Q10 in elderly subjects.

BACKGROUND: Alterations in the expression levels of genes and proteins involved in oxidative stress and DNA damage response underlie the phenotypic changes associated with aging. We have investigated whether the quality of dietary fat alters postprandial gene expression and protein levels involved in p53-dependent DNA repair and whether the supplementation with Coenzyme Q10 improves this situation in an elderly population. METHODS: Twenty participants were randomized to receive three isocaloric diets each for 4 weeks: Mediterranean diet supplemented with Coenzyme Q10, Mediterranean diet, saturated fatty acid-rich diet. After a 12-hour fast, volunteers consumed a breakfast with a fat composition similar to that consumed in each of the diets. Gadd45a, Gadd45b, OGG1, APE-1/Ref-1, DNApolß, and XPC gene expression and nuclear Gadd45a, APE-1/Ref-1, and DNApolß protein levels were determined in peripheral blood mononuclear cells. RESULTS: Mediterranean diet and Mediterranean diet supplemented with Coenzyme Q10diets downregulated Gadd45a protein levels compared with the saturated fatty acid-rich diet. Moreover, Mediterranean diet supplemented with Coenzyme Q10diet evoked lower postprandial Gadd45a, Gadd45b, XPC, DNApolß and OGG1 gene expression and lower APE-1/Ref-1 and DNApolß protein levels than the saturated fatty acid-rich diet. CONCLUSIONS: Our results support a beneficial effect of Mediterranean diet and Mediterranean diet supplemented with Coenzyme Q10 on DNA damage as compared to the detrimental action of a saturated fatty acid-rich diet, which triggers the p53-dependent DNA repair machinery.

Dietary fat differentially influences the lipids storage on the adipose tissue in metabolic syndrome patients.

PURPOSE: Adipose tissue is now recognized as a highly active metabolic and endocrine organ. Our aim was to investigate the effect of the dietary fat on the two main adipose tissue functions, endocrine and lipid store, by analyzing the adipose tissue gene expression from metabolic syndrome patients. METHODS: A randomized, controlled trial conducted within the LIPGENE study assigned 39 metabolic syndrome patients to 1 of 4 isoenergetic diets: (1) high-saturated fatty acid (HSFA), (2) high-monounsaturated fatty acid (HMUFA), (3) low-fat, high-complex carbohydrate diet supplemented with long-chain n-3 fatty acids (LFHCC n-3), and (4) low-fat, high-complex carbohydrate diet supplemented with placebo (LFHCC), for 12 weeks each. A fat challenge reflecting the fatty acid composition as the original diets was conducted post-intervention. RESULTS: The long-term consumption of HSFA, LFHCC, and LFHCC n-3 diets, but not HMUFA diet, decreased the perilipin fasting mRNA levels. LFHCC diet consumption increased fasting FABP4 expression, while it was reduced by the consumption of LFHCC n-3 diet. LFHCC meal reduced, while LFHCC n-3 meal intake increased postprandial CAV1 expression. CONCLUSION: The quantity and quality of dietary fat induce differential lipid storage and processing related gene expression, which may interact with the expression of adipokines through common regulatory mechanisms.

Antioxidant system response is modified by dietary fat in adipose tissue of metabolic syndrome patients.

Metabolic syndrome (MetS) is associated with high oxidative stress, which is caused by an increased expression of NADPH-oxidase and a decreased expression of antioxidant enzymes in the adipose tissue. Our aim was to evaluate whether the quality and quantity of dietary fat can modify that process. A randomized, controlled trial conducted within the LIPGENE study assigned MetS patients to one of four diets for 12 wk each: (i) high-saturated fatty acid (HSFA), (ii) high-monounsaturated fatty acid (HMUFA), (iii) and (iv) two low-fat, high-complex carbohydrate diet supplemented with n-3 polyunsaturated fatty acids (LFHCC n3), or placebo (LFHCC). A fat challenge reflecting the same fatty acid composition as the original diets was conducted post-intervention. The intake of an HSFA meal induced a higher postprandial increase in gp91phox and p67phox mRNA levels than after the intake of HMUFA, LFHCC and LFHCC n-3 meals (all p-values<0.05). The postprandial decrease in CAT, GPXs and TXNRD1 mRNA levels after the HSFA meal intake was higher than after the intake of HMUFA, LFHCC and LFHCC n-3 meals (all p-values<0.05). The intake of an HSFA meal induced a higher postprandial increase in KEAP1 mRNA levels than after the consumption of the HMUFA (P=.007) and LFHCC n-3 (P=.001) meals. Our study demonstrated that monounsaturated fat consumption reduces oxidative stress as compared to saturated fat by inducing higher postprandial antioxidant response in adipose tissue, and thus, replacing SFA for MUFA may be an effective dietary strategy to reduce the oxidative stress in MetS patients and its pathophysiological consequences.

Postprandial changes in the proteome are modulated by dietary fat in patients with metabolic syndrome.

Metabolic syndrome is a multicomponent disorder whose etiology is the result of a complex interaction between genetic, metabolic and environmental factors including dietary habits. Our aim was to identify proteome-diet interactions during the postprandial state after the acute intake of four meals with different qualities of fat in the proteome of peripheral blood mononuclear cells. A randomized controlled trial conducted within the LIPGENE study assigned 39 metabolic syndrome patients to one of four meals: a high-saturated-fatty-acid (HSFA) meal, a high-monounsaturated-fatty-acid (HMUFA) meal and two high-polyunsaturated-fatty-acid (from walnut) (HPUFA) meals supplemented with n-3 PUFA or placebo. We analyzed the postprandial changes in the whole proteome of both nuclear and cytoplasmic fractions of peripheral blood mononuclear cells by two-dimensional proteomics. Twenty-three proteins were differentially expressed. HSFA intake caused the postprandial increase of proteins responding to oxidative stress (HSPA1A, PDIA3 and PSME1) and DNA damage (SMC6), whereas HMUFA intake led to the up-regulation of HSPA1A and PDIA3. HPUFA meal supplementation with n-3 PUFA produced peroxisomal beta-oxidation inhibition by down-regulation of ECH1, a process related to insulin signaling improvement. In conclusion, HSFA meal intake causes deleterious postprandial changes in the proteome in terms of DNA damage and procoagulant state, which reflect a higher postprandial oxidative stress after HSFA meal intake as compared to intake of HMUFA and HPUFA meals. Moreover, the addition of long-chain n-3 PUFA to an HPUFA meal may improve insulin signaling and exerts an anti-inflammatory effect when compared to an HPUFA meal.

Dietary fat modifies the postprandial inflammatory state in subjects with metabolic syndrome: the LIPGENE study.

SCOPE: Our aim was to investigate whether the inflammatory state associated to metabolic syndrome (MetS) patients is affected by diets with different fat quality and quantity. METHODS AND RESULTS: Seventy-five subjects from LIPGENE cohort were included in this feeding trial and randomly assigned to one of four diets: high saturated fatty acids (HSFA); high monounsaturated fatty acids (HMUFA) and two low-fat, high complex carbohydrate (LFHCC) diets, supplemented with long-chain n-3 polyunsaturated fatty acids (LFHCC n-3) or placebo (LFHCC), for 12 weeks each. A postprandial fat challenge, reflecting the intervention dietary fat composition, was conducted post-intervention. The HMUFA diet significantly reduced postprandial nuclear transcription factor-kappaB (NF-kB) activity and the nuclear p65 protein levels relative to fasting values (p < 0.05). Furthermore, we observed a postprandial decrease in this protein with the HMUFA diet compared with the HSFA and LFHCC diets (p < 0.05). The postprandial response of inhibitory molecule from NF-kB mRNA levels increased with the HMUFA diet compared with the HSFA and LFHCC n-3 diets (p < 0.05). Postprandial tumor necrosis factor-α and Metalloproteinase 9 mRNA levels were also reduced after the HMUFA diet compared with the HSFA diet (p < 0.05). CONCLUSION: Our results indicate that the long-term consumption of a healthy diet model with HMUFA attenuates the postprandial inflammatory state associated with MetS.

Postprandial inflammatory response in adipose tissue of patients with metabolic syndrome after the intake of different dietary models.

SCOPE: Dysfunctional adipose tissue may be an important trigger of molecular inflammatory pathways that cause cardiovascular diseases. Our aim was to determine whether the specific quality and quantity of dietary fat produce differential postprandial inflammatory responses in adipose tissue from metabolic syndrome (MetS) patients. METHODS AND RESULTS: A randomized, controlled trial conducted within the LIPGENE study assigned MetS patients to 1 of 4 diets: (i) high-saturated fatty acid (HSFA), (ii) high-monounsaturated fatty acid (HMUFA), (iii) low-fat, high-complex carbohydrate diet supplemented with n-3 polyunsaturated fatty acids (PUFA) (LFHCC n-3), and (iv) low-fat, high-complex carbohydrate diet supplemented with placebo (LFHCC), for 12 wk each. A fat challenge reflecting the fatty acid composition as the original diets was conducted post-intervention. We found that p65 gene expression is induced in adipose tissue (p=0.003) at the postprandial state. In addition, IκBα (p<0.001), MCP-1 (p<0.001) and IL-1ß (p<0.001) gene expression was equally induced in the postprandial state, regardless of the quality and quantity of the dietary fat. Notably, IL-6 transcripts were only detected in the postprandial state. CONCLUSIONS: Our results indicate that individuals with MetS typically exhibit exacerbated adipose tissue postprandial inflammatory responses, which seem to be independent of the quality and quantity of dietary fat.

Identification and characterization of new functional truncated variants of somatostatin receptor subtype 5 in rodents.

Somatostatin and cortistatin exert multiple biological actions through five receptors (sst1-5); however, not all their effects can be explained by activation of sst1-5. Indeed, we recently identified novel truncated but functional human sst5-variants, present in normal and tumoral tissues. In this study, we identified and characterized three novel truncated sst5 variants in mice and one in rats displaying different numbers of transmembrane-domains [TMD; sst5TMD4, sst5TMD2, sst5TMD1 (mouse-variants) and sst5TMD1 (rat-variant)]. These sst5 variants: (1) are functional to mediate ligand-selective-induced variations in [Ca(2+)]i and cAMP despite being truncated; (2) display preferential intracellular distribution; (3) mostly share full-length sst5 tissue distribution, but exhibit unique differences; (4) are differentially regulated by changes in hormonal/metabolic environment in a tissue- (e.g., central vs. systemic) and ligand-dependent manner. Altogether, our results demonstrate the existence of new truncated sst5-variants with unique ligand-selective signaling properties, which could contribute to further understanding the complex, distinct pathophysiological roles of somatostatin and cortistatin.

Melanotrope secretory cycle is regulated by physiological inputs via the hypothalamus.

Previously, it has been shown that background color conditions regulate the overall activity of the frog intermediate lobe by varying the proportions of the two subtypes of melanotropes existing in the gland, the highly active or secretory melanotropes and hormone storage melanotropes, depending on melanocyte-stimulating hormone requirements. However, the factors and mechanisms underlying these background-induced changes are still unknown. In the present study, we investigated whether hypothalamic factors known to regulate melanotrope cell function can induce changes in vitro similar to those caused by background adaptation in vivo. We found that the inhibitors apomorphine (a dopamine receptor agonist) and neuropeptide Y decreased the number of active melanotropes and increased simultaneously that of storage melanotropes. On the other hand, the stimulator TRH increased the number of active cells and concomitantly reduced that of storage cells. Inasmuch as none of these treatments modified the apoptotic and proliferation rates in melanotrope cells, it appears that these hypothalamic factors caused actual interconversions of cells from a subpopulation to its counterpart. Taken together, these findings suggest that the hypothalamus would control melanotrope activity not only through short-term regulation of hormone synthesis and release, but also through a long-term regulation of the secretory phenotype of these cells whereby the activity of the intermediate lobe would be adjusted to fulfill the hormonal requirements imposed by background conditions.