The genetic contribution to non-syndromic human obesity. Nat Rev Genet. 2009;10:431-442. [PMID: 19506576 DOI: 10.1038/nrg2594]

Polygene Varianten und Epigenetik bei Adipositas

Hintergrund

Durch molekulargenetische Analysen wurde eine kleine Anzahl von Hauptgenen identifiziert, die Übergewicht (Body Mass Index, BMI ≥ 25 kg/m2) und Adipositas (BMI ≥ 30 kg/m2) bei Menschen mit bedingen können. Die zugrunde liegenden Mutationen sind selten. Die genetische Prädisposition zur Entwicklung einer Adipositas ist meist polygener Natur.

Ziel der Arbeit

Darstellung der polygenen Formen der Adipositas und epigenetischer Befunde.

Material und Methoden

Literaturübersicht.

Ergebnisse und Diskussion

Metaanalysen genomweiter Assoziationsstudien (GWAMA) haben bisher mehr als 100 Polygene oder polygene Loci identifiziert, die genomweit mit dem BMI assoziiert sind. Jedes einzelne Polygen leistet nur einen kleinen Beitrag zur Entwicklung einer Adipositas. Effektstärken liegen im Bereich von ca. 100 g bis 1,5 kg. Eine Reihe solcher prädisponierenden Genvarianten (Allele) findet sich bei adipösen Probanden. Allerdings tragen auch normalgewichtige und schlanke Individuen diese Allele, wenn auch in geringerer Frequenz. Diese Allele können durch statistische Analysen als Adipositas-Risikoallele identifiziert und validiert werden. Vor Kurzem haben sogenannte Cross-Disorder- und Cross-Phänotyp-Analysen zur Identifizierung von Genen geführt, die nicht allein durch Analysen der einzelnen Erkrankungen/Phänotypen nachgewiesen werden konnten. Funktionelle in-vitro- und in-vivo-Studien der GWAS-abgeleiteten Polygene könnten zu einem besseren Verständnis der molekulargenetischen Mechanismen der Körpergewichtsregulation führen. Erste genomweite Methylierungsmusteranalysen und Studien zu metastabilen Epiallelen tragen zudem zu einem besseren Verständnis der Pathomechanismen der Adipositas bei.

Strategies to increase the efficacy of using gut microbiota for the modulation of obesity

Obesity is one of the most serious global public health challenges of the 21st century. The adjustment of gut microbiota is often recommended as an efficient strategy to treat obesity. This modulation of gut microbiota can be performed by many methods, including dietary intervention, antibiotic application, the use of prebiotics and probiotics, bariatric surgery and faecal microbiota transplantation. In most cases, positive effects have been observed in response to treatment, but invalid and even contrary effects have also been observed in some cases due to factors that are unrelated to intervention methods, such as genetic factors, patient age or gender, environmental microbiota, climate, geography and lifestyle. These factors can cause variation of gut microbial populations and thus should also be taken into consideration when selecting modulation strategies.

Metabolically Healthy Obese and Incident Cardiovascular Disease Events Among 3.5 Million Men and Women

BACKGROUND

Previous studies have been unclear about the cardiovascular risks for metabolically healthy obese individuals.

OBJECTIVES

This study examined the associations among metabolically healthy obese individuals and 4 different presentations of incident cardiovascular disease in a contemporary population.

METHODS

We used linked electronic health records (1995 to 2015) in The Health Improvement Network (THIN) to assemble a cohort of 3.5 million individuals, 18 years of age or older and initially free of cardiovascular disease. We created body size phenotypes defined by body mass index categories (underweight, normal weight, overweight, and obesity) and 3 metabolic abnormalities (diabetes, hypertension, and hyperlipidemia). The primary endpoints were the first record of 1 of 4 cardiovascular presentations (coronary heart disease [CHD], cerebrovascular disease, heart failure, and peripheral vascular disease).

RESULTS

During a mean follow-up of 5.4 years, obese individuals with no metabolic abnormalities had a higher risk of CHD (multivariate-adjusted hazard ratio [HR]: 1.49; 95% confidence interval [CI]: 1.45 to 1.54), cerebrovascular disease (HR: 1.07; 95% CI: 1.04 to 1.11), and heart failure (HR: 1.96; 95% CI: 1.86 to 2.06) compared with normal weight individuals with 0 metabolic abnormalities. Risk of CHD, cerebrovascular disease, and heart failure in normal weight, overweight, and obese individuals increased with increasing number of metabolic abnormalities.

CONCLUSIONS

Metabolically healthy obese individuals had a higher risk of coronary heart disease, cerebrovascular disease, and heart failure than normal weight metabolically healthy individuals. Even individuals who are normal weight can have metabolic abnormalities and similar risks for cardiovascular disease events.

Anthropometric and cardiometabolic risk factors in parents and child obesity in Segamat, Malaysia

Background

There is little evidence regarding risk factors for child obesity in Asian populations, including the role of parental anthropometric and cardiometabolic risk factors. We examined the relation between parental risk factors and child obesity in a Malaysian population.

Methods

We used data from health and demographic surveillance conducted by the South East Asia Community Observatory in Segamat, Malaysia. Analyses included 9207 individuals (4806 children, 2570 mothers and 1831 fathers). Child obesity was defined based on the World Health Organization 2007 reference. We assessed the relation between parental anthropometric (overweight, obesity and central obesity) and cardiometabolic (systolic hypertension, diastolic hypertension and hyperglycaemia) risk factors and child obesity, using mixed effects Poisson regression models with robust standard errors.

Results

We found a high burden of overweight and obesity among children in this population (30% overweight or obese). Children of one or more obese parents had a 2-fold greater risk of being obese compared with children of non-obese parents. Sequential adjustment for parental and child characteristics did not materially affect estimates (fully adjusted relative risk for obesity in both parents: 2.39, 95% confidence interval: 1.82, 3.10, P < 0.001; P for trend < 0.001). These associations were not modified by parental or child sex. We found no consistent evidence for associations between parental cardiometabolic risk factors and child obesity.

Conclusions

Parental obesity was strongly associated with child obesity in this population. Further exploration of the behavioural and environmental drivers of these associations may help inform strategies addressing child obesity in Asia.

Genetics of non-syndromic childhood obesity and the use of high-throughput DNA sequencing technologies

BACKGROUND

Childhood obesity is a serious public health problem associated with the development of several chronic diseases, such as type 2 diabetes mellitus, dyslipidemia, and hypertension. The elevated prevalence of obesity is mostly due to inadequate diet and lifestyle, but it is also influenced by genetic factors.

OBJECTIVES

To review recent advances in the field of the genetics of obesity. We summarize the list of genes associated with the rare non-syndromic forms of obesity, and explain their function. Furthermore, we discuss the technologies that are available for the genetic diagnosis of obesity.

RESULTS

Several studies reported that single gene variants cause Mendelian forms of obesity, determined by mutations of major effect in single genes. Rare, non-syndromic forms of obesity are a result of loss-of-function mutations in genes that act on the development and function of the hypothalamus or the leptin-melanocortin pathway. These variants disrupt enzymes and receptors that play a role in energy homeostasis, resulting in severe early-onset obesity and endocrine dysfunctions. Different approaches and technologies have been used to understand the genetic background of obesity. Currently, whole genome and whole exome sequencing are important diagnostic tools to identify new genes and variants associated with severe obesity, but other approaches are also useful at individual or population levels, such as linkage analysis, candidate gene sequencing, chromosomal microarray analysis, and genome-wide association studies.

CONCLUSIONS

The understanding of the genetic causes of obesity and the usefulness and limitations of the genetic diagnostic approaches can contribute to the development of new personalized therapeutic targets against obesity.

Genetics of body fat mass and related traits in a pig population selected for leanness

Obesity is characterized as the excessive accumulation of body fat and has a complex genetic foundation in humans including monogenic high-risk mutations and polygenic contributions. Domestic pigs represent a valuable model on an obesity-promoting high-caloric diet while constantly evaluated for body characteristics. As such, we investigated the genetics of obesity-related traits, comprising subcutaneous fat thickness, lean mass percentage, and growth rate, in a pig population. We conducted genome-wide association analyses using an integrative approach of single-marker regression models and multi-marker Bayesian analyses. Thus, we identified 30 genomic regions distributed over 14 different chromosomes contributing to the variation in obesity-related traits. In these regions, we validated the association of four candidate genes that are functionally connected to the regulation of appetite, processes of adipogenesis, and extracellular matrix formation. Our findings revealed fundamental genetic factors which deserves closer attention regarding their roles in the etiology of obesity.

Metabolic profiling by gas chromatography-mass spectrometry of energy metabolism in high-fat diet-fed obese mice

A novel, selective and sensitive single-ion monitoring (SIM) gas chromatography-mass spectrometry (GCMS) method was developed and validated for the determination of energy metabolites related to glycolysis, the tricarboxylic acid (TCA) cycle, glutaminolysis, and fatty acid β-oxidation. This assay used N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA) containing 1% tert-butyldimethylchlorosilane (TBDMCS) as derivatizing reagent and was highly reproducible, sensitive, specific and robust. The assay was used to analyze liver tissue and serum from C57BL/6N obese mice fed a high-fat diet (HFD) and C57BL/6N mice fed normal chow for 8 weeks. HFD-fed mice serum displayed statistically significantly reduced concentrations of pyruvate, citrate, succinate, fumarate, and 2-oxoglutarate, with an elevated concentration of pantothenic acid. In liver tissue, HFD-fed mice exhibited depressed levels of glycolysis end-products pyruvate and lactate, glutamate, and the TCA cycle intermediates citrate, succinate, fumarate, malate, and oxaloacetate. Pantothenate levels were 3-fold elevated accompanied by a modest increased gene expression of Scl5a6 that encodes the pantothenate transporter SLC5A6. Since both glucose and fatty acids inhibit coenzyme A synthesis from pantothenate, it was concluded that these data were consistent with downregulated fatty acid β-oxidation, glutaminolysis, glycolysis, and TCA cycle activity, due to impaired anaplerosis. The novel SIM GCMS assay provided new insights into metabolic effects of HFD in mice.

Transcriptome assembly and candidate genes involved in nutritional programming in the swordtail fish Xiphophorus multilineatus

BACKGROUND

Nutritional programming takes place in early development. Variation in the quality and/or quantity of nutrients in early development can influence long-term health and viability. However, little is known about the mechanisms of nutritional programming. The live-bearing fish Xiphophorus multilineatus has the potential to be a new model for understanding these mechanisms, given prior evidence of nutritional programming influencing behavior and juvenile growth rate. We tested the hypotheses that nutritional programming would influence behaviors involved in energy homeostasis as well gene expression in X. multilineatus.

METHODS

We first examined the influence of both juvenile environment (varied in nutrition and density) and adult environment (varied in nutrition) on behaviors involved in energy acquisition and energy expenditure in adult male X. multilineatus. We also compared the behavioral responses across the genetically influenced size classes of males. Males stop growing at sexual maturity, and the size classes of can be identified based on phenotypes (adult size and pigment patterns). To study the molecular signatures of nutritional programming, we assembled a de novo transcriptome for X. multilineatus using RNA from brain, liver, skin, testis and gonad tissues, and used RNA-Seq to profile gene expression in the brains of males reared in low quality (reduced food, increased density) and high quality (increased food, decreased density) juvenile environments.

RESULTS

We found that both the juvenile and adult environments influenced the energy intake behavior, while only the adult environment influenced energy expenditure. In addition, there were significant interactions between the genetically influenced size classes and the environments that influenced energy intake and energy expenditure, with males from one of the four size classes (Y-II) responding in the opposite direction as compared to the other males examined. When we compared the brains of males of the Y-II size class reared in a low quality juvenile environment to males from the same size class reared in high quality juvenile environment, 131 genes were differentially expressed, including metabolism and appetite master regulator agrp gene.

DISCUSSION

Our study provides evidence for nutritional programming in X. multilineatus, with variation across size classes of males in how juvenile environment and adult diet influences behaviors involved in energy homeostasis. In addition, we provide the first transcriptome of X. multilineatus, and identify a group of candidate genes involved in nutritional programming.

Genes, emotions and gut microbiota: The next frontier for the gastroenterologist

Most medical specialties including the field of gastroenterology are mainly aimed at treating diseases rather than preventing them. Genomic medicine studies the health/disease process based on the interaction of the human genes with the environment. The gastrointestinal (GI) system is an ideal model to analyze the interaction between our genes, emotions and the gut microbiota. Based on the current knowledge, this mini-review aims to provide an integrated synopsis of this interaction to achieve a better understanding of the GI disorders related to bad eating habits and stress-related disease. Since human beings are the result of an evolutionary process, many biological processes such as instincts, emotions and behavior are interconnected to guarantee survival. Nourishment is a physiological need triggered by the instinct of survival to satisfy the body’s energy demands. The brain-gut axis comprises a tightly connected neural-neuroendocrine circuitry between the hunger-satiety center, the dopaminergic reward system involved in the pleasure of eating and the gut microbiota that regulates which food we eat and emotions. However, genetic variations and the consumption of high-sugar and high-fat diets have overridden this energy/pleasure neurocircuitry to the point of addiction of several foodstuffs. Consequently, a gut dysbiosis generates inflammation and a negative emotional state may lead to chronic diseases. Balancing this altered processes to regain health may involve personalized-medicine and genome-based strategies. Thus, an integrated approach based on the understanding of the gene-emotions-gut microbiota interaction is the next frontier that awaits the gastroenterologist to prevent and treat GI disorders associated with obesity and negative emotions.

Copy number variations in "classical" obesity candidate genes are not frequently associated with severe early-onset obesity in children

BACKGROUND

Obesity is genetically heterogeneous and highly heritable, although polymorphisms explain the phenotype in only a small proportion of obese children. We investigated the presence of copy number variations (CNVs) in "classical" genes known to be associated with (monogenic) early-onset obesity in children.

METHODS

In 194 obese Caucasian children selected for early-onset and severe obesity from our obesity cohort we screened for deletions and/or duplications by multiplex ligation-dependent probe amplification reaction (MLPA). As we found one MLPA probe to interfere with a polymorphism in SIM1 we investigated its association with obesity and other phenotypic traits in our extended cohort of 2305 children.

RESULTS

In the selected subset of most severely obese children, we did not find CNV with MLPA in POMC, LEP, LEPR, MC4R, MC3R or MC2R genes. However, one SIM1 probe located at exon 9 gave signals suggestive for SIM1 insufficiency in 52 patients. Polymerase chain reaction (PCR) analysis identified this as a false positive result due to interference with single nucleotide polymorphism (SNP) rs3734354/rs3734355. We, therefore, investigated for associations of this polymorphism with obesity and metabolic traits in our extended cohort. We found rs3734354/rs3734355 to be associated with body mass index-standard deviation score (BMI-SDS) (p = 0.003), but not with parameters of insulin metabolism, blood pressure or food intake.

CONCLUSIONS

In our modest sample of severely obese children, we were unable to find CNVs in well-established monogenic obesity genes. Nevertheless, we found an association of rs3734354 in SIM1 with obesity of early-onset type in children, although not with obesity-related traits.

Obesity, cardiovascular disease, and role of vitamin C on inflammation: a review of facts and underlying mechanisms

Obesity means the accumulation of excessive fat that may interfere with the maintenance of optimal state of health. Obesity causes cardiac and vascular disease through well-known mediators such as hypertension, type-2 diabetes mellitus, and dyslipidemia, but there are evidences for other mediators such as chronic inflammation, oxidative stress, and thrombosis. The decreased levels of antioxidants factors and nitric oxide predispose to further cardiovascular adverse events. To reduce the risks, antioxidants can help by neutralizing the free radicals and protecting from damage by donating electrons. Having the capacity, vitamin C protects from oxidative stress, prevention of non-enzymatic glycosylation of proteins, and enhances arterial dilation through its effect on nitric oxide release. It also decreases lipid peroxidation, and alleviates inflammation. The anti-inflammatory property of vitamin C could be attributed to ability to modulate the NF-_kB DNA binding activity and down-regulation in the hepatic mRNA expression for the interleukins and tumor factors.

Elevated fasting insulin levels increase the risk of abdominal obesity in Korean men

OBJECTIVE

This study was designed to investigate whether an elevated fasting insulin level predicts abdominal obesity.

STUDY DESIGN

A cohort study was conducted with 13,707 non-obese Korean men. They were categorized into 4 groups according to the quartile of fasting insulin level, and followed up from 2005 to 2010. Incidence rates of obesity were compared among the 4 groups during follow-up, and a Cox proportional hazards model was used to calculate hazard ratios (HRs) for abdominal obesity according to fasting insulin level.

RESULTS

The overall incidence rate of obesity was 16.2%, but the rate increased in proportion to the fasting insulin level (quartiles 1-4: 9.8%, 12.4%, 16.9%, 25.5%, P<0.001). When HR of the 1st quartile was regarded as the reference, HRs for abdominal obesity increased proportionally to baseline fasting insulin level in an unadjusted model. However, after adjustment for covariates, including baseline waist circumference (WC), only in the quartile 4 group was the statistical significance of the association maintained [quartile 2-4; abdominal obesity: 0.89 (0.76-1.02), 1.00 (0.86-1.14) and 1.24 (1.08-1.43), P for trend <0.001].

CONCLUSION

Although the risk of incident abdominal obesity was highest in the group with the highest fasting insulin levels, an overall proportional relationship between fasting insulin level and incident abdominal obesity was not found. Additionally, this association was largely accounted for by baseline WC.

Gene variants in the FTO gene are associated with adiponectin and TNF-alpha levels in gestational diabetes mellitus

BACKGROUND

Obesity may have a role in the development of gestational diabetes mellitus (GDM). Single-nucleotide-polymorphisms (SNPs) of the FTO (fat mass and obesity associated) gene have been associated with obesity. The aim of this study was to investigate SNPs rs8050136, rs9939609, and rs1421085 of the FTO gene in women with GDM and their associations with maternal pre-pregnancy weight and body mass index, gestational weight gain and mediators of insulin resistance in GDM like leptin, adiponectin, ghrelin and tumor necrosis factor-alpha (TNF-alpha), compared with healthy pregnant controls.

METHODS

80 women with GDM and 80 women with normal pregnancy were considered for the present study. Genotyping of selected SNPs in all study subjects was done using the Taq-Man assay and the adipokines and ghrelin were measured by immunoassays. Chi square test, odds ratios (OR) and their respective 95% confidence intervals were used to measure the strength of association between FTO SNPs and GDM.

RESULTS

There was no association among FTO SNPs and GDM. Interestingly, in GDM group, women carrying the risk alleles of the three SNPs had increased TNF-alpha, and decreased adiponectin levels; these associations remained significant after adjusting for pre-gestational body weight and age. Moreover, the risk allele of rs1421085 was also associated with increased weight gain during pregnancy.

CONCLUSIONS

The FTP SNPs rs8050136, rs9939609, and rs1421085 are not a major genetic regulator in the etiology of GDM in the studied ethnic group. However, these SNPs were associated with adiponectin and TNF-alpha concentrations in GDM subjects.

Interaction between the obesity-risk gene FTO and the dopamine D2 receptor gene ANKK1/TaqIA on insulin sensitivity

AIMS/HYPOTHESIS

Variations in FTO are the strongest common genetic determinants of adiposity, and may partly act by influencing dopaminergic signalling in the brain leading to altered reward processing that promotes increased food intake. Therefore, we investigated the impact of such an interaction on body composition, and peripheral and brain insulin sensitivity.

METHODS

Participants from the Tübingen Family study (n = 2245) and the Malmö Diet and Cancer study (n = 2921) were genotyped for FTO SNP rs8050136 and ANKK1 SNP rs1800497. Insulin sensitivity in the caudate nucleus, an important reward area in the brain, was assessed by fMRI in 45 participants combined with intranasal insulin administration.

RESULTS

We found evidence of an interaction between variations in FTO and an ANKK1 polymorphism that associates with dopamine (D2) receptor density. In cases of reduced D2 receptor availability, as indicated by the ANKK1 polymorphism, FTO variation was associated with increased body fat and waist circumference and reduced peripheral insulin sensitivity. Similarly, altered central insulin sensitivity was observed in the caudate nucleus in individuals with the FTO obesity-risk allele and diminished D2 receptors.

CONCLUSIONS/INTERPRETATION

The effects of variations in FTO are dependent on dopamine D2 receptor density (determined by the ANKK1 polymorphism). Carriers of both risk alleles might, therefore, be at increased risk of obesity and diabetes.

Neuroendocrinological and Epigenetic Mechanisms Subserving Autonomic Imbalance and HPA Dysfunction in the Metabolic Syndrome

Impact of environmental stress upon pathophysiology of the metabolic syndrome (MetS) has been substantiated by epidemiological, psychophysiological, and endocrinological studies. This review discusses recent advances in the understanding of causative roles of nutritional factors, sympathomedullo-adrenal (SMA) and hypothalamic-pituitary adrenocortical (HPA) axes, and adipose tissue chronic low-grade inflammation processes in MetS. Disturbances in the neuroendocrine systems for leptin, melanocortin, and neuropeptide Y (NPY)/agouti-related protein systems have been found resulting directly in MetS-like conditions. The review identifies candidate risk genes from factors shown critical for the functioning of each of these neuroendocrine signaling cascades. In its meta-analytic part, recent studies in epigenetic modification (histone methylation, acetylation, phosphorylation, ubiquitination) and posttranscriptional gene regulation by microRNAs are evaluated. Several studies suggest modification mechanisms of early life stress (ELS) and diet-induced obesity (DIO) programming in the hypothalamic regions with populations of POMC-expressing neurons. Epigenetic modifications were found in cortisol (here HSD11B1 expression), melanocortin, leptin, NPY, and adiponectin genes. With respect to adiposity genes, epigenetic modifications were documented for fat mass gene cluster APOA1/C3/A4/A5, and the lipolysis gene LIPE. With regard to inflammatory, immune and subcellular metabolism, PPARG, NKBF1, TNFA, TCF7C2, and those genes expressing cytochrome P450 family enzymes involved in steroidogenesis and in hepatic lipoproteins were documented for epigenetic modifications.

White Pitaya (Hylocereus undatus) Juice Attenuates Insulin Resistance and Hepatic Steatosis in Diet-Induced Obese Mice

Insulin resistance and hepatic steatosis are the most common complications of obesity. Pitaya is an important source of phytochemicals such as polyphenols, flavonoid and vitamin C which are related to its antioxidant activity. The present study was conducted to evaluate the influence of white pitaya juice (WPJ) on obesity-related metabolic disorders (e.g. insulin resistance and hepatic steatosis) in high-fat diet-fed mice. Forty-eight male C57BL/6J mice were assigned into four groups and fed low-fat diet with free access to water or WPJ, or fed high-fat diet with free access to water or WPJ for 14 weeks. Our results showed that administration of WPJ improved high-fat diet-induced insulin resistance, hepatic steatosis and adipose hypertrophy, but it exerted no influence on body weight gain in mice. Hepatic gene expression analysis indicated that WPJ supplement not only changed the expression profile of genes involved in lipid and cholesterol metabolism (Srebp1, HMGCoR, Cpt1b, HL, Insig1 and Insig2) but also significantly increased the expression levels of FGF21-related genes (Klb, FGFR2, Egr1 and cFos). In conclusion, WPJ protected from diet-induced hepatic steatosis and insulin resistance, which was associated with the improved FGF21 resistance and lipid metabolism.

Physical activity and FTO genotype by physical activity interactive influences on obesity

Background

Although the effect of the fat mass and obesity-associated (FTO) gene on adiposity is well established, there is a lack of evidence whether physical activity (PA) modifies the effect of FTO variants on obesity in Latino populations. Therefore, the purpose of this study was to examine PA influences and interactive effects between FTO variants and PA on measures of adiposity in Latinos.

Results

After controlling for age and sex, participants who did not engage in regular PA exhibited higher BMI, fat mass, HC, and WC with statistical significance (P < 0.001). Although significant associations between the three FTO genotypes and adiposity measures were found, none of the FTO genotype by PA interaction assessments revealed nominally significant associations. However, several of such interactive influences exhibited considerable trend towards association.

Conclusions

These data suggest that adiposity measures are associated with PA and FTO variants in Latinos, but the impact of their interactive influences on these obesity measures appear to be minimal. Future studies with large sample sizes may help to determine whether individuals with specific FTO variants exhibit differential responses to PA interventions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12863-016-0357-6) contains supplementary material, which is available to authorized users.

Central nervous system regulation of intestinal lipid and lipoprotein metabolism

PURPOSE OF REVIEW

In response to nutrient availability, the small intestine and brain closely communicate to modulate energy homeostasis and metabolism. The gut-brain axis involves complex nutrient sensing mechanisms and an integration of neuronal and hormonal signaling. This review summarizes recent evidence implicating the gut-brain axis in regulating lipoprotein metabolism, with potential implications for the dyslipidemia of insulin resistant states.

RECENT FINDINGS

The intestine and brain possess distinct mechanisms for sensing lipid availability, which triggers subsequent regulation of feeding, glucose homeostasis, and adipose tissue metabolism. More recently, central receptors, neuropeptides, and gut hormones that communicate with the brain have been shown to modulate hepatic and intestinal lipoprotein metabolism via parasympathetic and sympathetic signaling. Gut-derived glucagon-like peptides appear to be particularly important in modulating the intestinal secretion of chylomicron particles via a novel brain-gut axis. Dysregulation of these pathways may contribute to postprandial diabetic dyslipidemia.

SUMMARY

Emerging evidence implicates the central and enteric nervous systems in controlling many aspects of lipid and lipoprotein metabolism. Bidirectional communication between the gut and brain involving neuronal pathways and gut peptides is critical for regulating feeding and metabolism, and forms a neuroendocrine circuit to modulate dietary fat absorption and intestinal production of atherogenic chylomicron particles.

PCSK1 Variants and Human Obesity

PCSK1, encoding prohormone convertase 1/3 (PC1/3), was one of the first genes linked to monogenic early-onset obesity. PC1/3 is a protease involved in the biosynthetic processing of a variety of neuropeptides and prohormones in endocrine tissues. PC1/3 activity is essential for the activating cleavage of many peptide hormone precursors implicated in the regulation of food ingestion, glucose homeostasis, and energy homeostasis, for example, proopiomelanocortin, proinsulin, proglucagon, and proghrelin. A large number of genome-wide association studies in a variety of different populations have now firmly established a link between three PCSK1 polymorphisms frequent in the population and increased risk of obesity. Human subjects with PC1/3 deficiency, a rare autosomal-recessive disorder caused by the presence of loss-of-function mutations in both alleles, are obese and display a complex set of endocrinopathies. Increasing numbers of genetic diagnoses of infants with persistent diarrhea has recently led to the finding of many novel PCSK1 mutations. PCSK1-deficient infants experience severe intestinal malabsorption during the first years of life, requiring controlled nutrition; these children then become hyperphagic, with associated obesity. The biochemical characterization of novel loss-of-function PCSK1 mutations has resulted in the discovery of new pathological mechanisms affecting the cell biology of the endocrine cell beyond simple loss of enzyme activity, for example, dominant-negative effects of certain mutants on wild-type PC1/3 protein, and activation of the cellular unfolded protein response by endoplasmic reticulum-retained mutants. A better understanding of these molecular and cellular pathologies may illuminate possible treatments for the complex endocrinopathy of PCSK1 deficiency, including obesity.

Beyond BMI: Conceptual Issues Related to Overweight and Obese Patients

BMI is widely used as a measure of weight status and disease risks; it defines overweight and obesity based on statistical criteria. BMI is a score; neither is it biologically sound nor does it reflect a suitable phenotype worthwhile to study. Because of its limited value, BMI cannot provide profound insight into obesity biology and its co-morbidity. Alternative assessments of weight status include detailed phenotyping by body composition analysis (BCA). However, predicting disease risks, fat mass, and fat-free mass as assessed by validated techniques (i.e., densitometry, dual energy X ray absorptiometry, and bioelectrical impedance analysis) does not exceed the value of BMI. Going beyond BMI and descriptive BCA, the concept of functional body composition (FBC) integrates body components into regulatory systems. FBC refers to the masses of body components, organs, and tissues as well as to their inter-relationships within the context of endocrine, metabolic and immune functions. FBC can be used to define specific phenotypes of obesity, e.g. the sarcopenic-obese patient. Well-characterized obesity phenotypes are a precondition for targeted research (e.g., on the genomics of obesity) and patient-centered care (e.g., adequate treatment of individual obese phenotypes such as the sarcopenic-obese patient). FBC contributes to a future definition of overweight and obesity based on physiological criteria rather than on body weight alone.

Extensive alterations of the whole-blood transcriptome are associated with body mass index: results of an mRNA profiling study involving two large population-based cohorts

Background

Obesity, defined as pathologically increased body mass index (BMI), is strongly related to an increased risk for numerous common cardiovascular and metabolic diseases. It is particularly associated with insulin resistance, hyperglycemia, and systemic oxidative stress and represents the most important risk factor for type 2 diabetes (T2D). However, the pathophysiological mechanisms underlying these associations are still not completely understood. Therefore, in order to identify potentially disease-relevant BMI-associated gene expression signatures, a transcriptome-wide association study (TWAS) on BMI was performed.

Methods

Whole-blood mRNA levels determined by array-based transcriptional profiling were correlated with BMI in two large independent population-based cohort studies (KORA F4 and SHIP-TREND) comprising a total of 1977 individuals.

Results

Extensive alterations of the whole-blood transcriptome were associated with BMI: More than 3500 transcripts exhibited significant positive or negative BMI-correlation. Three major whole-blood gene expression signatures associated with increased BMI were identified. The three signatures suggested: i) a ratio shift from mature erythrocytes towards reticulocytes, ii) decreased expression of several genes essentially involved in the transmission and amplification of the insulin signal, and iii) reduced expression of several key genes involved in the defence against reactive oxygen species (ROS).

Conclusions

Whereas the first signature confirms published results, the other two provide possible mechanistic explanations for well-known epidemiological findings under conditions of increased BMI, namely attenuated insulin signaling and increased oxidative stress. The putatively causative BMI-dependent down-regulation of the expression of numerous genes on the mRNA level represents a novel finding. BMI-associated negative transcriptional regulation of insulin signaling and oxidative stress management provide new insights into the pathogenesis of metabolic syndrome and T2D.

Electronic supplementary material

The online version of this article (doi:10.1186/s12920-015-0141-x) contains supplementary material, which is available to authorized users.

Development of an educational intervention to promote healthy eating and physical activity in Mexican school-age children

Mexico has the highest and most alarming rates of childhood obesity worldwide. A study conducted in the State of Mexico revealed that one of every three children presents overweight or obesity. The objective of this paper is to provide a step-by-step description of the design and implementation of an educational intervention to promote healthy eating and physical activity called "Healthy Recess". The educational intervention was designed using the six stages of the Health Communication Process. This methodological model allowed identifying the needs of school-age children on information and participation in activities. In order to improve the strategy, adjustments were made to the print and audiovisual materials as well as to assessment tools. Typography was modified as well as the color of the images in student's workbook and facilitator's; special effects of the videos were increased; the narration of the radio spots was improved and common words and phrases were included. The Health Communication Process is an effective tool for program planners to design interventions aimed at managing prevalent health problems such as overweight and obesity in school-age children.

Reduced Inhibition of Return to Food Images in Obese Individuals

Previous research has shown that obese individuals may be biased towards attending to food over non-food information, and this bias may contribute to the development and/or maintenance of obesity. The present study sought to extend our understanding of maladaptive attentional processing in this population by investigating whether obese individuals have difficulty in disengaging attention from food compared with non-food images, relative to normal-weight controls. To address this question, we measured inhibition of return (IOR) in an attentional cueing task. The participants were 29 obese and 35 normal-weight satiated females without eating disorders. The obese group displayed less IOR to food images than the normal-weight group, while there was no difference in IOR between the groups for non-food images. This suggests that obese females have greater difficulty disengaging attention from food than normal-weight females. Our findings provide a new focus for studies investigating maintenance factors in obesity and are discussed in relation to a theory of incentive-sensitisation.

Knockdown of LYRM1 rescues insulin resistance and mitochondrial dysfunction induced by FCCP in 3T3-L1 adipocytes

LYR motif-containing 1 (LYRM1) was recently discovered to be involved in adipose tissue homeostasis and obesity-associated insulin resistance. We previously demonstrated that LYRM1 overexpression might contribute to insulin resistance and mitochondrial dysfunction. Additionally, knockdown of LYRM1 enhanced insulin sensitivity and mitochondrial function in 3T3-L1 adipocytes. We investigated whether knockdown of LYRM1 in 3T3-L1 adipocytes could rescue insulin resistance and mitochondrial dysfunction induced by the cyanide p-trifluoromethoxyphenyl-hydrazone (FCCP), a mitochondrion uncoupler, to further ascertain the mechanism by which LYRM1 is involved in obesity-associated insulin resistance. Incubation of 3T3-L1 adipocytes with 1 µM FCCP for 12 h decreased insulin-stimulated glucose uptake, reduced intracellular ATP synthesis, increased intracellular reactive oxygen species (ROS) production, impaired insulin-stimulated Glucose transporter type 4 (GLUT4) translocation, and diminished insulin-stimulated tyrosine phosphorylation of Insulin receptor substrate-1 (IRS-1) and serine phosphorylation of Protein Kinase B (Akt). Knockdown of LYRM1 restored insulin-stimulated glucose uptake, rescued intracellular ATP synthesis, reduced intracellular ROS production, restored insulin-stimulated GLUT4 translocation, and rescued insulin-stimulated tyrosine phosphorylation of IRS-1 and serine phosphorylation of Akt in FCCP-treated 3T3-L1 adipocytes. This study indicates that FCCP-induced mitochondrial dysfunction and insulin resistance are ameliorated by knockdown of LYRM1.

Genetic variants in LEP, LEPR, and MC4R explain 30% of severe obesity in children from a consanguineous population

OBJECTIVE

Single gene mutations leading to severe obesity have so far been identified in 3-5% cases in European populations. However, prevalence of these pathogenic mutations has not systematically been examined in specific consanguineous populations. Here we describe the incidence of obesity-associated mutations through a step-wise sequence analysis, in a cohort of 73 Pakistani children with severe obesity from consanguineous families.

METHODS

Initially, all subjects were screened for mutations in coding regions of leptin (LEP) and melanocortin 4 receptor (MC4R) genes by direct sequencing. Subjects negative for mutation in these genes were screened using microdroplet PCR enrichment and NGS. Genomic structural variation was assessed by genotyping. Serum leptin, insulin, and cortisol were determined by ELISA.

RESULTS

Among 73 children with severe obesity (BMI SDS > 3.0), we identified 22 probands and 5 relatives, carrying 10 different loss-of-function homozygous mutations in LEP, leptin receptor (LEPR), and MC4R genes, including 4 novel variants. Hypercortisolemia was significantly emphasized in LEP mutation carriers.

CONCLUSIONS

The prevalence of pathogenic mutations in genes known to directly influence leptin-melanocortin signaling is 30% in our cohort. The results of this study emphasize the desirability of undertaking systematic and in-depth genetic analysis of cases with severe obesity in specific consanguineous populations.

A polyphenol-rich cranberry extract protects from diet-induced obesity, insulin resistance and intestinal inflammation in association with increased Akkermansia spp. population in the gut microbiota of mice

OBJECTIVE

The increasing prevalence of obesity and type 2 diabetes (T2D) demonstrates the failure of conventional treatments to curb these diseases. The gut microbiota has been put forward as a key player in the pathophysiology of diet-induced T2D. Importantly, cranberry (Vaccinium macrocarpon Aiton) is associated with a number of beneficial health effects. We aimed to investigate the metabolic impact of a cranberry extract (CE) on high fat/high sucrose (HFHS)-fed mice and to determine whether its consequent antidiabetic effects are related to modulations in the gut microbiota.

DESIGN

C57BL/6J mice were fed either a chow or a HFHS diet. HFHS-fed mice were gavaged daily either with vehicle (water) or CE (200 mg/kg) for 8 weeks. The composition of the gut microbiota was assessed by analysing 16S rRNA gene sequences with 454 pyrosequencing.

RESULTS

CE treatment was found to reduce HFHS-induced weight gain and visceral obesity. CE treatment also decreased liver weight and triglyceride accumulation in association with blunted hepatic oxidative stress and inflammation. CE administration improved insulin sensitivity, as revealed by improved insulin tolerance, lower homeostasis model assessment of insulin resistance and decreased glucose-induced hyperinsulinaemia during an oral glucose tolerance test. CE treatment was found to lower intestinal triglyceride content and to alleviate intestinal inflammation and oxidative stress. Interestingly, CE treatment markedly increased the proportion of the mucin-degrading bacterium Akkermansia in our metagenomic samples.

CONCLUSIONS

CE exerts beneficial metabolic effects through improving HFHS diet-induced features of the metabolic syndrome, which is associated with a proportional increase in Akkermansia spp.

Pro-Opiomelanocortin (POMC) Neurones, POMC-Derived Peptides, Melanocortin Receptors and Obesity: How Understanding of this System has Changed Over the Last Decade

Following the cloning of the melanocortin receptor and agouti protein genes, a model was developed for the central melanocortin system with respect to the regulation of energy and glucose homeostasis. This model comprised leptin regulation of melanocortin peptides and agouti-related peptide (AgRP) produced from central pro-opiomelanocortin (POMC) and AgRP neurones, respectively, as well as AgRP competitive antagonism of melanocortin peptides activating melanocortin 4 receptor (MC4R) to Gαs and the cAMP signalling pathway. In the last decade, there have been paradigm shifts in our understanding of the central melanocortin system as a result of the application of advanced new technologies, including Cre-LoxP transgenic mouse technology, pharmacogenetics and optogenetics. During this period, our understanding of G protein coupled receptor signal transduction has also dramatically changed, such that these receptors are now known to exist in the plasma membrane oscillating between various inactive and active conformational states, and the active states signal through G protein-dependent and G protein-independent pathways. The present review focuses on evidence obtained over the past decade that has changed our understanding of POMC gene expression and regulation in the central nervous system, POMC and AgRP neuronal circuitry, neuroanatomical functions of melanocortin receptors, melanocortin 3 receptor (MC3R) and MC4R, and signal transduction through MC3R and MC4R.

Immune regulation of metabolic homeostasis in health and disease

Obesity is an increasingly prevalent disease worldwide. While genetic and environmental factors are known to regulate the development of obesity and associated metabolic diseases, emerging studies indicate that innate and adaptive immune cell responses in adipose tissue have critical roles in the regulation of metabolic homeostasis. In the lean state, type 2 cytokine-associated immune cell responses predominate in white adipose tissue and protect against weight gain and insulin resistance through direct effects on adipocytes and elicitation of beige adipose. In obesity, these metabolically beneficial immune pathways become dysregulated, and adipocytes and other factors initiate metabolically deleterious type 1 inflammation that impairs glucose metabolism. This review discusses our current understanding of the functions of different types of adipose tissue and how immune cells regulate adipocyte function and metabolic homeostasis in the context of health and disease and highlights. We also highlight the potential of targeting immuno-metabolic pathways as a therapeutic strategy to treat obesity and associated diseases.

Association between rs12970134 Near MC4R and adiposity indexes in a homogenous population of Caucasian schoolchildren

BACKGROUND

To assess whether previously identified obesity-susceptibility loci were associated with overweight/obesity risk in a homogeneous population of Caucasian schoolchildren and whether these associations varied with age.

METHODS

Seven hundred and forty-five schoolchildren (353 boys, mean age: 8.3 ± 1.4 years) underwent anthropometric assessments. A saliva sample was collected for DNA extraction and assessment of 19 single-nucleotide polymorphisms previously associated with obesity.

RESULTS

Only the rs12970134 in the MC4R gene was significantly associated with overweight/obesity risk, with a higher frequency of the AA risk genotype in children with a BMI >85th (8.3%) than in those with a BMI <85th percentile (3.0%), p = 0.001; odds ratio (95% CI) of 1.544 (1.192-1.998), p = 0.001, after adjusting for age, sex and pubertal stage. BMI standard deviation scores (SDS) and waist-to-height ratio (W/Hr) progressively increased across the rs12970134 genotypes (GG vs. AG vs. AA): BMI SDS, p = 0.004; W/Hr, p = 0.009. When dividing the study population into two groups based on the median age of participants (8.3 years), the differences in BMI SDS and W/Hr across the MC4R genotypes persisted only in children older than 8.3 years.

CONCLUSIONS

In a population of Caucasian schoolchildren, the rs12970134 MC4R variant was significantly associated with excess body weight, particularly in children older than 8 years of age.

Models and mechanisms for hippocampal dysfunction in obesity and diabetes

Clinical studies suggest that obesity and Type 2 (insulin-resistant) diabetes impair the structural integrity of medial temporal lobe regions involved in memory and confer greater vulnerability to neurological insults. While eliminating obesity and its endocrine comorbidities would be the most straightforward way to minimize cognitive risk, structural barriers to physical activity and the widespread availability of calorically dense, highly palatable foods will likely necessitate additional strategies to maintain brain health over the lifespan. Research in rodents has identified numerous correlates of hippocampal functional impairment in obesity and diabetes, with several studies demonstrating causality in subsequent mechanistic studies. This review highlights recent work on pathways and cell-cell interactions underlying the synaptic consequences of obesity, diabetes, or in models with both pathological conditions. Although the mechanisms vary across different animal models, immune activation has emerged as a shared feature of obesity and diabetes, with synergistic exacerbation of neuroinflammation in model systems with both conditions. This review discusses these findings with reference to the benefits of incorporating existing models from the fields of obesity and metabolic disease. Many transgenic lines with basal metabolic alterations or differential susceptibility to diet-induced obesity have yet to be characterized with respect to their cognitive and synaptic phenotype. Adopting these models, and building on the extensive knowledge base used to generate them, is a promising avenue for understanding interactions between peripheral disease states and neurodegenerative disorders.

The effect of rs9939609 FTO gene polymorphism on weight loss after laparoscopic sleeve gastrectomy

PURPOSE

Remarkable differences in weight loss have been observed in obese patients undergoing laparoscopic sleeve gastrectomy (LSG). These high variations might be partly explained by genetic factors. The rs9939609 fat mass and obesity-associated gene (FTO) polymorphism has been implicated in the susceptibility of obesity. We aimed to explore the effects of the rs9939609 FTO gene polymorphism on weight loss among severely obese patients applying for LSG.

MATERIALS AND METHODS

All individuals were analyzed for the FTO rs9939609 gene polymorphism. A total of 74 morbid obese patients (20 male, 54 female) were operated. Body weight and body mass index (BMI) were measured at before LSG and after surgery at the sixth month.

RESULTS

Twenty-eight patients (37.8%) had genotype TT (wild-type allel), 36 patients (48.6%) had genotype TA, and 10 patients (13.5%) had genotype AA. In both wild-type group and mutant group, BMI and weight levels decreased at the sixth month after surgery. Percent of excess weight loss (EWL) at 6 months of follow-up was similar in both groups. There were no differences between the mutant and wild-type groups percent of EWL at the sixth month after applying LSG.

CONCLUSION

Our data showed that the rs9939609 FTO gene polymorphism is not a useful genetic test prior to LSG to help clinicians predicting the weight loss for severely obese patients in short-term follow-up.

Association of pediatric obesity and migraine with comparison to tension headache and samples from other countries

The link between body weight and headache has hardly been examined in children. The aim was to evaluate the association of obesity and migraine in selected pediatric patients and compare the findings with the literature. Data on clinical symptoms, headache type, and body mass index standard deviation score were derived from the medical files of 245 patients with migraine and 87 with tension headache. Comparison of the 3 subgroups of migraine patients of normal weight, overweight, and obese with the corresponding body mass index standard deviation score subgroups of patients with tension-type headache yielded no statistically significant differences in frequency of headache attacks per month, or duration of headache attacks in hours. These results call into question earlier reports linking headache and obesity in children. Differences in findings between our study and those in the literature highlight several factors that should be addressed in further studies. A larger sample size may reveal more significant results.

A novel MC4R mutation associated with childhood-onset obesity: A case report

The melanocortin-4-receptor gene (MC4R) is a key regulator of energy homeostasis, food intake and body weight. MC4R gene mutations are associated with early-onset severe obesity. Most patients are heterozygotes, with some reports of homozygotes and compound heterozygotes. The authors report a case involving an eight-year-old girl with progressive weight gain from infancy, body mass index 44 kg/m(2) (>97th percentile), hyperphagia, hyperinsulinemia and increased linear growth. There was no phenotype of morbid obesity in the parents or sibling. Coding regions and intron-exon boundaries of the genes encoding leptin, leptin receptor, pro-opiomelanocortin and MC4R were analyzed. Two heterozygous coding mutations in the MCR4 gene (S94N and C293R) were detected, of which the second has not been previously reported. The mutations were on opposite chromosomes, confirming compound heterozygosity. The molecular findings and clinical features associated with this novel MC4R mutation are described. The authors emphasize that rare mutations can be found in some patients with severe childhood-onset obesity.

Cohort of birth modifies the association between FTO genotype and BMI

A substantial body of research has explored the relative roles of genetic and environmental factors on phenotype expression in humans. Recent research has also sought to identify gene-environment (or g-by-e) interactions, with mixed success. One potential reason for these mixed results may relate to the fact that genetic effects might be modified by changes in the environment over time. For example, the noted rise of obesity in the United States in the latter part of the 20th century might reflect an interaction between genetic variation and changing environmental conditions that together affect the penetrance of genetic influences. To evaluate this hypothesis, we use longitudinal data from the Framingham Heart Study collected over 30 y from a geographically relatively localized sample to test whether the well-documented association between the rs993609 variant of the FTO (fat mass and obesity associated) gene and body mass index (BMI) varies across birth cohorts, time period, and the lifecycle. Such cohort and period effects integrate many potential environmental factors, and this gene-by-environment analysis examines interactions with both time-varying contemporaneous and historical environmental influences. Using constrained linear age-period-cohort models that include family controls, we find that there is a robust relationship between birth cohort and the genotype-phenotype correlation between the FTO risk allele and BMI, with an observed inflection point for those born after 1942. These results suggest genetic influences on complex traits like obesity can vary over time, presumably because of global environmental changes that modify allelic penetrance.

Group 2 innate lymphoid cells promote beiging of white adipose tissue and limit obesity

Obesity is an increasingly prevalent disease regulated by genetic and environmental factors. Emerging studies indicate that immune cells, including monocytes, granulocytes and lymphocytes, regulate metabolic homeostasis and are dysregulated in obesity. Group 2 innate lymphoid cells (ILC2s) can regulate adaptive immunity and eosinophil and alternatively activated macrophage responses, and were recently identified in murine white adipose tissue (WAT) where they may act to limit the development of obesity. However, ILC2s have not been identified in human adipose tissue, and the mechanisms by which ILC2s regulate metabolic homeostasis remain unknown. Here we identify ILC2s in human WAT and demonstrate that decreased ILC2 responses in WAT are a conserved characteristic of obesity in humans and mice. Interleukin (IL)-33 was found to be critical for the maintenance of ILC2s in WAT and in limiting adiposity in mice by increasing caloric expenditure. This was associated with recruitment of uncoupling protein 1 (UCP1)(+) beige adipocytes in WAT, a process known as beiging or browning that regulates caloric expenditure. IL-33-induced beiging was dependent on ILC2s, and IL-33 treatment or transfer of IL-33-elicited ILC2s was sufficient to drive beiging independently of the adaptive immune system, eosinophils or IL-4 receptor signalling. We found that ILC2s produce methionine-enkephalin peptides that can act directly on adipocytes to upregulate Ucp1 expression in vitro and that promote beiging in vivo. Collectively, these studies indicate that, in addition to responding to infection or tissue damage, ILC2s can regulate adipose function and metabolic homeostasis in part via production of enkephalin peptides that elicit beiging.

Exome sequencing followed by genotyping suggests SYPL2 as a susceptibility gene for morbid obesity

Recently developed high-throughput sequencing technology shows power to detect low-frequency disease-causing variants by deep sequencing of all known exons. We used exome sequencing to identify variants associated with morbid obesity. DNA from 100 morbidly obese adult subjects and 100 controls were pooled (n=10/pool), subjected to exome capture, and subsequent sequencing. At least 100 million sequencing reads were obtained from each pool. After several filtering steps and comparisons of observed frequencies of variants between obese and non-obese control pools, we systematically selected 144 obesity-enriched non-synonymous, splicing site or 5' upstream single-nucleotide variants for validation. We first genotyped 494 adult subjects with morbid obesity and 496 controls. Five obesity-associated variants (nominal P-value<0.05) were subsequently genotyped in 1425 morbidly obese and 782 controls. Out of the five variants, only rs62623713:A>G (NM_001040709:c.A296G:p.E99G) was confirmed. rs62623713 showed strong association with body mass index (beta=2.13 (1.09, 3.18), P=6.28 × 10(-5)) in a joint analysis of all 3197 genotyped subjects and had an odds ratio of 1.32 for obesity association. rs62623713 is a low-frequency (2.9% minor allele frequency) non-synonymous variant (E99G) in exon 4 of the synaptophysin-like 2 (SYPL2) gene. rs62623713 was not covered by Illumina or Affymetrix genotyping arrays used in previous genome-wide association studies. Mice lacking Sypl2 has been reported to display reduced body weight. In conclusion, using exome sequencing we identified a low-frequency coding variant in the SYPL2 gene that was associated with morbid obesity. This gene may be involved in the development of excess body fat.

Ethnic differences in pre-adipocyte intracellular lipid accumulation and alkaline phosphatase activity

Alkaline phosphatase (ALP) increases lipid accumulation in human pre-adipocytes. This study was performed to assess whether ethnic differences in the prevalence of obesity in African and European females are related to differences in pre-adipocyte lipid accretion and ALP activity. Pre-adipocytes were isolated from 13 black and 14 white females. Adipogenesis was quantified using the lipid dye, Oil red O, whilst ALP activity was assayed in cell extracts on day zero and 12days after initiating adipogenesis. Lipid levels (OD units/mg protein) were lower in pre-adipocytes from white than black females on day 0 (0.36±0.05 versus 0.44±0.03, respectively; p<0.0005) and day 12 (1.18±0.14 versus 1.80±0.22, respectively; p<0.0005), as was ALP activity (mU/mg protein) on day zero (36.5±5.8 versus 136.4±10.9, respectively; p<0.0005) and day 12 (127±16 versus 278±27, respectively; p<0.0005). Treatment of pre-adipocytes with histidine, an ALP inhibitor, blocked lipid accumulation. Thus, lipid uptake is higher in pre-adipocytes isolated from black compared to white females which parallels the obesity prevalence rates in these population groups. The reason for higher fat accumulation in pre-adipocytes isolated from black females may be related to higher ALP activity.

Genetic vulnerability to diabetes and obesity: does education offset the risk?

The prevalence of type 2 diabetes (T2D) and obesity has recently increased dramatically. These common diseases are likely to arise from the interaction of multiple genetic, socio-demographic and environmental risk factors. While previous research has found genetic risk and education to be strong predictors of these diseases, few studies to date have examined their joint effects. This study investigates whether education modifies the association between genetic background and risk for type 2 diabetes (T2D) and obesity. Using data from non-Hispanic Whites in the Health and Retirement Study (HRS, n = 8398), we tested whether education modifies genetic risk for obesity and T2D, offsetting genetic effects; whether this effect is larger for individuals who have high risk for other (unobserved) reasons, i.e., at higher quantiles of HbA1c and BMI; and whether effects differ by gender. We measured T2D risk using Hemoglobin A1c (HbA1c) level, and obesity risk using body-mass index (BMI). We constructed separate genetic risk scores (GRS) for obesity and diabetes respectively based on the most current available information on the single nucleotide polymorphism (SNPs) confirmed as genome-wide significant predictors for BMI (29 SNPs) and diabetes risk (39 SNPs). Linear regression models with years of schooling indicate that the effect of genetic risk on HbA1c is smaller among people with more years of schooling and larger among those with less than a high school (HS) degree compared to HS degree-holders. Quantile regression models show that the GRS × education effect systematically increased along the HbA1c outcome distribution; for example the GRS × years of education interaction coefficient was -0.01 (95% CI = -0.03, 0.00) at the 10th percentile compared to -0.03 (95% CI = -0.07, 0.00) at the 90th percentile. These results suggest that education may be an important socioeconomic source of heterogeneity in responses to genetic vulnerability to T2D.

"Vicious circles": the development of morbid obesity

Although there has been extensive research around the etiology of moderate obesity, there are still important questions relating to the development and lived experience of extreme obesity. We present a synthesis of data from two in-depth qualitative studies in which morbidly obese participants (N = 31) were able to explain the development of the condition in their own terms. We identified consistent themes in the two datasets, and undertook a detailed data synthesis. Particularly salient themes in the development of morbid obesity related to family structures and early socialization experiences, and the role of emotional distress was dominant in both initial weight gain and ongoing cycles of loss and regain. All informants accepted some responsibility for their health state, but identified a number of mitigating factors that limited personal culpability that were often related to the fulfillment of gendered social expectations.

Molecular characterization, expression profiles, and analysis of Qinchuan cattle SIRT1 gene association with meat quality and body measurement traits (Bos taurus)

Silent information regulator (SIRT1), was closely associated with senescence, metabolism, and apoptosis. The objective of this study was to investigate whether SIRT1 gene could be used as a candidate gene in the breeding process of Qinchuan cattle. Via sequencing technology conducted in 453 individuals of Qinchuan cattle, single nucleotide polymorphisms (G25764A, A25846G, and T25868C) with 5 haplotypes and 6 combined genotypes in 3' untranslated region of SIRT1 gene were identified. In addition, three loci were significantly associated with some of the body measurements and meat quality traits in Qinchuan cattle (P < 0.05), and the H2H2 (GG-AA-CC) diplotypes had better performance than other combinations in Qinchuan cattle. These results suggest that the SIRT1 gene could be used in marker assisted selection to improve the production traits of Qinchuan cattle.

New candidate loci identified by array-CGH in a cohort of 100 children presenting with syndromic obesity

Syndromic obesity is defined by the association of obesity with one or more feature(s) including developmental delay, dysmorphic traits, and/or congenital malformations. Over 25 syndromic forms of obesity have been identified. However, most cases remain of unknown etiology. The aim of this study was to identify new candidate loci associated with syndromic obesity to find new candidate genes and to better understand molecular mechanisms involved in this pathology. We performed oligonucleotide microarray-based comparative genomic hybridization in a cohort of 100 children presenting with syndromic obesity of unknown etiology, after exhaustive clinical, biological, and molecular studies. Chromosomal copy number variations were detected in 42% of the children in our cohort, with 23% of patients with potentially pathogenic copy number variants. Our results support that chromosomal rearrangements are frequently associated with syndromic obesity with a variety of contributory genes having relevance to either obesity or developmental delay. A list of inherited or apparently de novo duplications and deletions including their enclosed genes and not previously linked to syndromic obesity was established. Proteins encoded by several of these genes are involved in lipid metabolism (ACOXL, MSMO1, MVD, and PDZK1) linked with nervous system function (BDH1 and LINGO2), neutral lipid storage (PLIN2), energy homeostasis and metabolic processes (CDH13, CNTNAP2, CPPED1, NDUFA4, PTGS2, and SOCS6).

Novel LEPR mutations in obese Pakistani children identified by PCR-based enrichment and next generation sequencing

OBJECTIVE

Mutations in leptin receptor gene (LEPR) result in early onset extreme adiposity. However, their prevalence in different populations is not known. Indeed, LEPR screening by gold standard Sanger sequencing has been limited by its large size and the cost. One-step PCR-based targeted enrichment could be an option for rapid and cost effective molecular diagnosis of monogenic forms of obesity.

METHODS

The study is based on 39 unrelated severely obese Pakistani children, previously shown to be negative for leptin (LEP) and melanocortin 4 receptor (MC4R) gene mutations, from an initial cohort of 62 probands. Patient samples were analyzed by microdroplet PCR-enrichment (RainDance technologies) targeting coding exons of 26 obesity-associated genes combined with next generation sequencing. Hormone levels were analyzed by ELISA.

RESULTS

The analysis revealed two novel homozygous LEPR mutations, an essential splice site mutation in exon 15 (c.2396-1 G>T), and a nonsense mutation in exon 10 (c.1675 G>A). Both probands had high leptin levels and were phenotypically indistinguishable from age-matched leptin-deficient subjects from the same population.

CONCLUSIONS

The two subjects carrying homozygous LEPR mutations, reported here for the first time in the Pakistani population, constitute 3% of the whole cohort of severely obese children (compared to 17% for LEP and 3% for MC4R).