Obesity-induced p53 activation in insulin-dependent and independent tissues is inhibited by beta-adrenergic agonist in diet-induced obese rats

Sting and p53 DNA repair pathways are compromised in Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia. A common finding in AD is DNA damage. Double-strand DNA breaks (DSBs) are particularly hazardous to neurons because their post-mitotic state forces neurons to rely on error-prone and potentially mutagenic mechanisms to repair DNA breaks. However, it remains unclear whether DNA damage results from increased DNA damage or failure of DNA repair. Oligomerization of the tumor suppressor protein p53 is an essential part of DSB repair, and p53 phosphorylated on S15 is an indicator of DNA damage. We report that the monomer:dimer ratio of phosphorylated (S15) p53 is increased by 2.86-fold in temporal lobes of AD patients compared to age-matched controls, indicating that p53 oligomerization is compromised in AD. In vitro oxidation of p53 with 100 nM H2O2 produced a similar shift in the monomer:dimer ratio. A COMET test showed a higher level of DNA degradation in AD consistent with double-strand DNA damage or inhibition of repair. Protein carbonylation was also elevated (190% of control), indicating elevated oxidative stress in AD patients. Levels of the DNA repair support protein 14-3-3σ, γ-H2AX, a phosphorylated histone marking double strand DNA breaks, and phosphorylated ataxia telangiectasia mutated (ATM) protein were all increased. cGAS-STING-interferon signaling was impaired in AD and was accompanied by a depletion of STING protein from Golgi and a failure to elevate interferon despite the presence of DSBs. The results suggest that oxidation of p53 by ROS could inhibit the DDR and decrease its ability to orchestrate DSB repair by altering the oligomerization state of p53. The failure of immune-stimulated DNA repair may contribute to cell loss in AD and suggests new therapeutic targets for AD.

Alterations of DNA methylation and expression of genes related to thyroid hormone metabolism in colon epithelium of obese patients

Background

Colorectal cancer is common among obese individuals. The purpose of the current study was to determine changes in DNA methylation status and mRNA expression of thyroid hormone receptor beta (THRB), as a tumor suppressor, and thyroid hormone inactivating enzyme, type 3 deiodinase (DIO3) genes, in human epithelial colon tissues of healthy obese individuals.

Methods

Colon biopsies were analyzed by methylation sensitive-high resolution melting (MS-HRM) to investigate promoter methylation of DIO3 and THRB, and by quantitative real-time polymerase chain reaction to assay expression of DIO3 and THRB mRNA on eighteen obese and twenty-one normal-weight healthy men.

Results

There was no significant difference in mean methylation levels at the THRB promoter region between the two groups. Nevertheless, obesity decreased THRB expression levels, significantly (P < 0.05; fold change: 0.19). Furthermore, obesity attenuated DNA methylation (P < 0.001) and enhanced mRNA expression of DIO3 (P < 0.05; fold change: 3).

Conclusions

Our findings suggest that obesity may alter expression of THRB and DIO3 genes through epigenetic mechanism. Alterations of THRB and DIO3 expressions may predispose colon epithelium of obese patients to neoplastic transformation.

Non-Alcoholic Fatty Liver Disease and Metabolic Syndrome in Women: Effects of Lifestyle Modifications

Non-alcoholic fatty liver disease (NAFLD) is the most widespread liver disease, characterized by fatty acids liver accumulation and subsequent fibrosis. NAFLD prevalence ranges from 80% to 90% in obese subjects and is estimated to be around 50% in patients with metabolic syndrome. In this clinical scenario, diet and lifestyle modifications can play an important role. There are several imaging techniques that can accurately diagnose fatty liver. Recently, ultrasound has acquired a leading role in the diagnosis and follow-up of fatty liver disease. Furthermore, elastosonography represents a valid alternative to liver biopsy. Shear wave elastosonography evaluates the elastic and mechanical properties of liver tissue. The aim is to evaluate the effects of lifestyle and nutritional interventions and a loss of body weight during hepatic steatosis through ultrasonographic and elastosonographic techniques. Thirty-two female subjects with metabolic syndrome were subjected to clinical, anthropometric, and laboratory assessments, as well as abdominal ultrasonographic/elastosonographic measurements taken from enrollment time (T0) and after 3 months (T1) of lifestyle modifications. After 3 months of lifestyle changes, significant weight loss was observed, with a marked improvement in all adiposity indices. The laboratory parameters at T1 showed significant decreases in total and LDL cholesterol, triglycerides, basal blood glucose, 120 min glycaemia, basal insulin and HOMA Index (p < 0.001). A similar improvement was observed at T1 for steatosis degree (p < 0.01) and elastosonographic measurements (Kpa p < 0.001). The linear regression analysis of the baseline conditions documented that the size of the liver positively correlated with body weight, BMI, neck and waist circumferences, waist to height ratio (WhtR), insulin and HOMA Index, fat mass and visceral fat, and steatosis grade. After 3 months, the liver size showed improvement with positive correlations to all previous variables. Hepatic stiffness (Kpa) positively correlated with neck circumference, visceral fat, and ALT, with basal insulin, gamma-GT, and AST, and with waist circumference, WhtR, and fat mass. The degree of steatosis was positively correlated with more variables and with greater statistical significance at T1 with respect to T0. Particularly, the positive correlations between the degree of steatosis and neck circumference (p < 0.001), HOMA Index, and triglycerides (p < 0.001) appeared to be very significant. NAFLD management in women with metabolic syndrome should be focused on lifestyle modifications. Moreover, liver involvement and improvement at follow-up could be evaluated in a non-invasive manner through ultrasonographic and elastosonographic techniques.

The Effects of Continuous and Withdrawal Voluntary Wheel Running Exercise on the Expression of Senescence-Related Genes in the Visceral Adipose Tissue of Young Mice

Obesity has become a global medical problem. The upregulation of senescence-related markers in adipose tissue may cause impairment of adipose tissue and disorders of systemic metabolism. Weight control through diet has been found to ameliorate senescence in the adipose tissue. Exercise is also important in maintaining a healthy lifestyle, however, very few researchers have examined the relationship between senescence-related markers in adipose tissue. Dietary restriction is also reported to have a legacy effect, wherein the effects are maintained for some periods after the termination of the intervention. However, very few researchers have examined the relationship between exercise and senescence-related markers in adipose tissue. Besides, there is no study on the long-term effects of exercise. Hence, we investigated whether the exercise could change the expression of senescence-related genes in the visceral adipose tissue of young mice and whether there was a legacy effect of exercise for 10 weeks after the termination of exercise. Four-week-old male ICR mice were assigned to one of the three groups: 20 weeks of sedentary condition, 20 weeks of voluntary wheel running exercise, or 10 weeks of exercise followed by 10 weeks of sedentary condition. The mice showed decreased expression in genes related to senescence and senescence-associated secretory phenotype, such as p53, p16, and IL-6, in the visceral adipose tissue in response to exercise. These effects were maintained for 10 weeks after the mice stopped exercising. Our study is the first report that exercise reduces the expression of senescence-related genes in the visceral adipose tissue of young mice, and that exercise causes the legacy effect.

The role of adipose tissue secretion in the creation and pain level in osteoarthritis

Objectives. With increasing evidence regarding the metabolic basis of osteoarthritis (OA), we studied the relationship between adipose tissue and OA.

Methods. This study is part of an OA registry in the eastern part of Fars Province, Iran. Overall, 150 patients with OA and 300 sex matched individuals were selected as a control group. They were compared regarding adipokine concentration (leptin, adiponectin, resistin and visfatin), anthropo-metric indices, the Western Ontario and McMaster universities arthritis index score (WOMAC).

Results. All adipokine levels were higher among OA patients (p<0.001). After adjusting for age, sex, and body mass index (BMI), adipokines showed a significant and positive association with OA (B: 14.12, B: 9.92, B: 24.71 and B: 12.29 for leptin, adiponectin, visfatin, and resistin, respectively; p<0.001). Except the adiponectin that had a negative relationship with BMI in the OA group (r=–0.570, p<0.001), other adipokines had positive relationships with BMI (r=0.781, p<0.001; r=0.530, p<0.001; r=0.549, p<0.001 for leptin, visfatin, and resistin, respectively). Only leptin and adiponectin levels were correlated with pain (B: 0.045, –0.079 and p<0.05).

Conclusion. The present study shows that aside to the well-known role of mechanical stress in OA pathogenesis (weight load), leptin, adiponectin, visfatin, and resistin, which represent the adi-pose tissue independent on the weight, may play a chemical role in OA pathogenesis. In addition, leptin and adiponectin may be involved in the pain levels among patients with OA.

Improvement in fasting blood sugar, anthropometric measurement and hs-CRP after consumption of epigallocatechin-3-gallate (EGCG) in patients with type 2 diabetes mellitus

Purpose

The epigallocatechin gallate (EGCG) effect in diabetes has been investigated in animal studies, but results of clinical trials are inconsistent. Thus, this study aims to evaluate the effects of EGCG supplementation in patients with type 2 diabetes mellitus (T2DM).

Design/methodology/approach

A total of 50 patients with T2DM were recruited in a double-blind, randomized, placebo-controlled trial. The eligible participants were randomly allocated to EGCG (n = 25) and placebo (n = 25) groups. The EGCG group received two capsules of EGCG (each capsule contained 150 mg; Shari Made®, Iran) and placebo group was administered two capsules of placebo (starch) for eight weeks. A three-day 24-h dietary recall and anthropometric and laboratory measurements were carried out at the beginning and the end of the study.

Findings

At the end of the trial, weight and body mass index (BMI) were decreased significantly in both groups, but the reduction was not statistically significant between the two groups. Fasting blood sugar decreased significantly in EGCG group. No significant between-group and within-group differences were found in insulin, homeostatic model assessment of insulin resistance (HOMA-IR) and the quantitative insulin sensitivity check index values. The high-sensitive C-reactive protein (hs-CRP) was significantly reduced in the EGCG group (4.13 ± 0.48-3.93 ± 0.50, p = 0.003) compared to baseline.

Originality/value

This study showed that consuming 300 mg/day of EGCG for eight weeks in patients with T2DM caused a significant decrease in fasting blood glucose, body weight, BMI and hs-CRP compared to baseline. Therefore, the EGCG supplementation may improve glycemic control, anthropometric and inflammation status in T2DM.

p53 Functions in Adipose Tissue Metabolism and Homeostasis

As a tumor suppressor and the most frequently mutated gene in cancer, p53 is among the best-described molecules in medical research. As cancer is in most cases an age-related disease, it seems paradoxical that p53 is so strongly conserved from early multicellular organisms to humans. A function not directly related to tumor suppression, such as the regulation of metabolism in nontransformed cells, could explain this selective pressure. While this role of p53 in cellular metabolism is gradually emerging, it is imperative to dissect the tissue- and cell-specific actions of p53 and its downstream signaling pathways. In this review, we focus on studies reporting p53’s impact on adipocyte development, function, and maintenance, as well as the causes and consequences of altered p53 levels in white and brown adipose tissue (AT) with respect to systemic energy homeostasis. While whole body p53 knockout mice gain less weight and fat mass under a high-fat diet owing to increased energy expenditure, modifying p53 expression specifically in adipocytes yields more refined insights: (1) p53 is a negative regulator of in vitro adipogenesis; (2) p53 levels in white AT are increased in diet-induced and genetic obesity mouse models and in obese humans; (3) functionally, elevated p53 in white AT increases senescence and chronic inflammation, aggravating systemic insulin resistance; (4) p53 is not required for normal development of brown AT; and (5) when p53 is activated in brown AT in mice fed a high-fat diet, it increases brown AT temperature and brown AT marker gene expression, thereby contributing to reduced fat mass accumulation. In addition, p53 is increasingly being recognized as crucial player in nutrient sensing pathways. Hence, despite existence of contradictory findings and a varying density of evidence, several functions of p53 in adipocytes and ATs have been emerging, positioning p53 as an essential regulatory hub in ATs. Future studies need to make use of more sophisticated in vivo model systems and should identify an AT-specific set of p53 target genes and downstream pathways upon different (nutrient) challenges to identify novel therapeutic targets to curb metabolic diseases.

Dietary pattern in pregnancy and risk of gestational diabetes mellitus (GDM)

AIM

Among the most common metabolic disorders during pregnancy is gestational diabetes mellitus (GDM). This research was conducted to examine the dietary pattern in women with GDM.

MATERIAL AND METHODS

In this case-study, 204 pregnant women (104 cases and 100 control women) were chosen through convenient sampling and random sampling. The subjects' food intakes were assessed using semi-quantitative food frequency questionnaire, while their activities evaluated by physical activity questionnaire. Anthropometric indices were measured based on standard instructions, and the body mass index was calculated. The dietary patterns were determined using principal component analysis and its relationship with preeclampsia was tested using logistic regression method.

RESULTS

Unhealthy and healthy dietary patterns were found among the pregnant women. In the unhealthy group, after modifying the effect of confounding variables, a significant relationship was observed between dietary pattern and having gestational diabetes (OR = 2.838,95% CI:1.039-7.751). In the healthy group, on the other hand, the people in the fourth quartile had 149% and 184% higher chance not to catch gestational diabetes before and after modification with confounders, respectively (OR = 0.284,95% CI:0.096-0.838), when compared with people in the first quartile.

CONCLUSION

The findings indicated that selection of foods including fruits, vegetables, low-fat dairies, etc. as healthy dietary pattern is associated with diminished risk of GDM among pregnant women. Determining healthy dietary pattern during pregnancy, considering the foods consumed among pregnant women, as a useful and practical guide during this period can be publicized for training and nutritional interventions.

Waist circumference is a mediator of dietary pattern in Non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is an example of pathological fat accumulation in the liver and one of the major health conditions in the world. This study aimed to examine the independent role of dietary patterns in the development of NAFLD. In a cross-sectional study, 1500 individuals referred to a nutrition clinic were randomly selected, their demographic, anthropometric and blood metabolic indices were obtained, and food frequency questionnaires were completed for them. Liver stiffness was calculated using the NAFLD score formula and fibroscan. The two dominant dietary patterns identified were the “healthy” and “unhealthy dietary patterns”. A significant percentage of those with NAFLD (45%) were in the upper quartile of the unhealthy model; however, only 10% had the healthy pattern (p < 0.001). In this study, 32.9 and 13.9% of the healthy and unhealthy participants were in the upper quartile of the healthy diet pattern. Also, it was shown that waist circumference is a strong mediator of dietary patterns and NAFLD relationship, and the indirect effect of diet through abdominal circumference is 28 times greater than the direct effect on NAFLD. The results suggested that healthy and unhealthy dietary patterns are respectively associated with lower- and higher-risk of NAFLD but the role of waist circumference as a mediator deserves more consideration.

P53 modulates hepatic insulin sensitivity through NF-κB and p38/ERK MAPK pathways

Besides its well-established oncosuppressor activity, the role of p53 in regulating metabolic pathways has been recently identified. Nevertheless, the function of p53 with respect to insulin resistance appears highly controversial. To address this issue, we investigated the expression of p53 in experimental model of insulin resistance. Then we used activator (nutlin-3α) and inhibitor (pifithrin-α, PFT-α) of p53 in HepG2 cell. Here we showed that p53 protein level was decreased in the hepatic tissue of high-fat diet-induced insulin resistance mice, genetically diabetic ob/ob mice and palmitate (PA) treated HepG2 cells. And high expression of phosphor-p38, ERK1/2 and nuclear factor kappa B (NF-κB) p65 accompanied with low expression of p53. But activation of p53 with nutlin-3α prevented PA-induced reduction of glucose consumption and suppression of insulin signaling pathways. At the same time, nutlin-3α downregulated the activation of NF-κB, p38 and ERK1/2 pathways upon stimulation with PA. In contrast, inhibition of p53 with PFT-α decreased glucose consumption and suppressed insulin signaling pathway. Furthermore, PFT-α activated NF-κB, p38 and ERK1/2 pathways in HepG2 cells. Overall, these results suggest that p53 is involved in improving insulin sensitivity of hepatic cells via inhibition of mitogen-activated protein kinases (MAPKs) and NF-κB pathways.

Relationship between metabolic syndrome and osteoarthritis: The Fasa Osteoarthritis Study

BACKGROUND

An association between metabolic syndrome (MeS) and osteoarthritis (OA) has been reported in recent years; however, conflicting findings have been reported regarding this matter. Inhere we evaluated the relationship between different components of MeS and OA in a Fasa osteoarthritis registry (FOAS).

METHODS

The registry includes all OA cases who referred to Fasa hospital (Iran) since 2013. Overall, 131 patients with OA with a Kellgren & Lawrence (K&L) score >1 and 261 controls were compared.

RESULTS

Overall, 82.4% of individuals in the OA group and 40.8% of participants in the control group had MeS (P<0.001). Patients with OA had a 6.8 (95% CI: 4.1-11.4) higher chance of acquiring MeS. After adjusting for sex, age, and BMI, odds' ratio (OR) for acquiring MeS in OA group increased to 10.9 (95% CI: 5.5-21.8). Among MeS criteria's, high waist circumference (WC) has strongest correlation for acquiring OA (OR=27.535, 95% CI: 6.003-126.306).

CONCLUSION

Our findings revealed that metabolic markers are strongly associated with OA and the addition of each component of the MeS, significantly increases the risk of developing OA, therefore control of metabolic factors and appropriate screening must be considered in health policy making and prevention programs.

Molecular connections of obesity and aging: a focus on adipose protein 53 and retinoblastoma protein

Obesity is an induced health problem that human beings have been facing with non-optimal treatment so far. Humans are on average getting fatter with age, and obesity and aging interact each other to shorten lifetime and decrease life quality. Obesity also causes several aging related-disorders such as cancer, strokes, cardiovascular disease, high blood pressure and type 2 diabetes. So, the molecular connections between aging and obesity are promising targets for bio-medical researches and innovative therapies of many health problems. In this review, we discuss the findings of adipose p53 and Rb-two central molecular linkages between aging and obesity-on lipid metabolism and obesity.

Is p53 Involved in Tissue-Specific Insulin Resistance Formation?

p53 constitutes an extremely versatile molecule, primarily involved in sensing the variety of cellular stresses. Functional p53 utilizes a plethora of mechanisms to protect cell from deleterious repercussions of genotoxic insults, where senescence deserves special attention. While the impressive amount of p53 roles has been perceived solely by the prism of antioncogenic effect, its presence seems to be vastly connected with metabolic abnormalities underlain by cellular aging, obesity, and inflammation. p53 has been found to regulate multiple biochemical processes such as glycolysis, oxidative phosphorylation, lipolysis, lipogenesis, β-oxidation, gluconeogenesis, and glycogen synthesis. Notably, p53-mediated metabolic effects are totally up to results of insulin action. Accumulating amount of data identifies p53 to be a factor activated upon hyperglycemia or excessive calorie intake, thus contributing to low-grade chronic inflammation and systemic insulin resistance. Prominent signs of its actions have been observed in muscles, liver, pancreas, and adipose tissue being associated with attenuation of insulin signalling. p53 is of crucial importance for the regulation of white and brown adipogenesis simultaneously being a repressor for preadipocyte differentiation. This review provides a profound insight into p53-dependent metabolic actions directed towards promotion of insulin resistance as well as presenting experimental data regarding obesity-induced p53-mediated metabolic abnormalities.

Ability of dairy fat in inducing metabolic syndrome in rats

Background

The risk of heart diseases, diabetes and stroke is increased with higher metabolic risk factors. Models of diseases resulting from high-calorie diets have a significant role in pathophysiologic analysis of metabolic syndrome in rodents; but, these diets are considerably different from each other in various studies and may not be very similar to the metabolic syndrome model in humans. This study sought to make a model close to the disease in humans. 20 five-week old male Wistar rats were randomly assigned to two groups. For one of the groups, a high-calorie diet with 416 calories per 100 g with dairy-based fat was considered and, for another group, a control diet was given for 12 weeks. Weight changes, lipid profile, glucose values, Blood pressure, insulin and HOMA indices, were measured for both groups and weight changes were compared using repeated measures and independent t test; also, serum results were compared using independent t test.

Results

Values of weight, glucose, insulin, lipid profile and blood pressure, except HDL, had a tangible difference between two groups at the end of the study. HOMA-IR, HOMA-B and HOMA-S indicates a significant difference between the two groups after consumption high-energy diet.

Conclusion

The present study showed ability of dairy fat in gaining weight, insulin resistance and metabolic syndrome and provided the necessity of paying serious attention to the amount of fat intake from dairy sources.