Unconventional microarray design reveals the response to obesity is largely tissue specific: analysis of common and divergent responses to diet-induced obesity in insulin-sensitive tissues

A comprehensive review on high fat diet-induced diabetes mellitus: An epigenetic view

Modern lifestyle, genetics, nutritional overload through high-fat diet attributed prevalence and diabetes outcomes with various complications primarily due to obesity in which energy-dense diets frequently affect metabolic health. One possible issue usually associated with elevated chronic fat intake is insulin resistance, and hyperglycaemia constitutes an important function in altering the carbohydrates and lipids metabolism. Similarly, in assessing human susceptibility to weight gain and obesity, genetic variations play a central role, contributing to keen interest in identifying the possible role of epigenetics as a mediator of gene-environmental interactions influencing the production of type 2 diabetes mellitus and its related concerns. Epigenetic modifications associated with the acceptance of a sedentary lifestyle and environmental stress factors in response to energy intake and expenditure imbalances complement genetic alterations and lead to the production and advancement of metabolic disorders such as diabetes and obesity. Methylation of DNA, histone modifications and increases in the expression of non-coding RNAs can result in reduced transcriptional activity of key β-cell genes thus creating insulin resistance. Epigenetics contribute to changes in the expression of the underlying insulin resistance and insufficiency gene networks, along with low-grade obesity-related inflammation, increased ROS generation and DNA damage in multi organs. This review focused on epigenetic mechanisms and metabolic regulations associated with high fat diet (HFD)-induced diabetes mellitus.

Molecular docking analysis of stevioside with Akt and PPARγ

Stevioside is a diterpenoid glycoside consisting of an aglycone (steviol) and three glucose molecules. It is commonly used as an anti-hyperglycemic food because of its non-caloric property. Therefore, it is of interest to document the interactions of stevioside with AKT & PPAR-γ proteins using Autodock Vina PyRx docking techniques. Results of the docking studies indicate that stevioside had more than two hydrogen bond interactions with the AKT and PPAR γ protein for further consideration.

High Fat Rodent Models of Type 2 Diabetes: From Rodent to Human

Poor dietary habits contribute to increased incidences of obesity and related co-morbidities, such as type 2 diabetes (T2D). The biological, genetic, and pathological implications of T2D, are commonly investigated using animal models induced by a dietary intervention. In spite of significant research contributions, animal models have limitations regarding the translation to human pathology, which leads to questioning their clinical relevance. Important considerations include diet-specific effects on whole organism energy balance and glucose and insulin homeostasis, as well as tissue-specific changes in insulin and glucose tolerance. This review will examine the T2D-like phenotype in rodents resulting from common diet-induced models and their relevance to the human disease state. Emphasis will be placed on the disparity in percentages and type of dietary fat, the duration of intervention, and whole organism and tissue-specific changes in rodents. An evaluation of these models will help to identify a diet-induced rodent model with the greatest clinical relevance to the human T2D pathology. We propose that a 45% high-fat diet composed of approximately one-third saturated fats and two-thirds unsaturated fats may provide a diet composition that aligns closely to average Western diet macronutrient composition, and induces metabolic alterations mirrored by clinical populations.

Mesenchymal Stem Cells Shift Mitochondrial Dynamics and Enhance Oxidative Phosphorylation in Recipient Cells

Mesenchymal stem cells (MSCs) are the most commonly used cells in tissue engineering and regenerative medicine. MSCs can promote host tissue repair through several different mechanisms including donor cell engraftment, release of cell signaling factors, and the transfer of healthy organelles to the host. In the present study, we examine the specific impacts of MSCs on mitochondrial morphology and function in host tissues. Employing in vitro cell culture of inherited mitochondrial disease and an in vivo animal experimental model of low-grade inflammation (high fat feeding), we show human-derived MSCs to alter mitochondrial function. MSC co-culture with skin fibroblasts from mitochondrial disease patients rescued aberrant mitochondrial morphology from a fission state to a more fused appearance indicating an effect of MSC co-culture on host cell mitochondrial network formation. In vivo experiments confirmed mitochondrial abundance and mitochondrial oxygen consumption rates were elevated in host tissues following MSC treatment. Furthermore, microarray profiling identified 226 genes with differential expression in the liver of animals treated with MSC, with cellular signaling, and actin cytoskeleton regulation as key upregulated processes. Collectively, our data indicate that MSC therapy rescues impaired mitochondrial morphology, enhances host metabolic capacity, and induces widespread host gene shifting. These results highlight the potential of MSCs to modulate mitochondria in both inherited and pathological disease states.

Tissue Specific Impacts of a Ketogenic Diet on Mitochondrial Dynamics in the BTBRT+tf/j Mouse

The ketogenic diet (KD) has been utilized as a dietary therapeutic for nearly a century. One experimental model particularly responsive to the KD is the BTBR^T+tf/j (BTBR) mouse, which displays phenotypic characteristics of autism spectrum disorder (ASD) and insulin resistance. Recently, the study of impaired mitochondrial function has become a focal point of research investigating the pathophysiology of ASD. As highly dynamic organelles, mitochondria undergo constant fluctuations in morphology, biogenesis, and quality control in order to maintain cellular homeostasis. An important modifier of mitochondrial dynamics is energy availability. Therefore, the aim of this study was to examine the impact of a KD on mitochondrial dynamics in the liver and brain (prefrontal cortex) of the BTBR mouse model of ASD. Juvenile male C57Bl/6 (B6) and BTBR mice were age-matched to 5 weeks of age before being fed standard chow (CD, 13% kcal fat) or a KD (75% kcal fat) for 10–14 days. Analysis of brain tissue identified differences in mitochondrial gene expression but no correlation with protein levels. Unlike in the brain, KD led to decreased levels of mitochondrial proteins in the liver, despite increased gene expression. Consistent with decreased mitochondrial proteins, we also observed decreased mtDNA for all mice on the KD, demonstrating that the KD reduces the total amount of mitochondria in the liver. In order to explain the discrepancy between protein levels and gene expression, we investigated whether mitochondrial turnover via mitophagy was increased. To this end, we examined expression levels of the mitophagy regulator BNIP3 (BCL2/adenovirus E1B 19 kd-interacting protein 3). BNIP3 gene and protein expression were significantly elevated in liver of KD animals (p < 0.05), indicating the potential activation of mitophagy. Therefore, consumption of a KD exerts highly tissue-specific effects, ultimately increasing mitochondrial turnover in the liver, while gene and protein expression in the brain remaining tightly regulated.

Nutritional systems biology of type 2 diabetes

Type 2 diabetes (T2D) has become an increasingly challenging health burden due to its high morbidity, mortality, and heightened prevalence worldwide. Although dietary and nutritional imbalances have long been recognized as key risk factors for T2D, the underlying mechanisms remain unclear. The advent of nutritional systems biology, a field that aims to elucidate the interactions between dietary nutrients and endogenous molecular entities in disease-related tissues, offers unique opportunities to unravel the complex mechanisms underlying the health-modifying capacities of nutritional molecules. The recent revolutionary advances in omics technologies have particularly empowered this incipient field. In this review, we discuss the applications of multi-omics approaches toward a systems-level understanding of how dietary patterns and particular nutrients modulate the risk of T2D. We focus on nutritional studies utilizing transcriptomics, epigenomomics, proteomics, metabolomics, and microbiomics, and integration of diverse omics technologies. We also summarize the potential molecular mechanisms through which nutritional imbalances contribute to T2D pathogenesis based on these studies. Finally, we discuss the remaining challenges of nutritional systems biology and how the field can be optimized to further our understanding of T2D and guide disease management via nutritional interventions.

Consumption of polyphenol-rich peach and plum juice prevents risk factors for obesity-related metabolic disorders and cardiovascular disease in Zucker rats

Polyphenols from fruits have been implied in the prevention of risk factors for cardiometabolic disorders and cardiovascular disease. The purpose of this study was to investigate if the consumption of peach and plum juice has a protective effect against obesity and metabolic disorders that promote the development of cardiovascular diseases. Obese Zucker and lean rats were fed with peach, plum juice ad libitum or placebo. Body weight gain, biochemical markers and molecular markers for inflammation and cardiovascular disease in heart tissue were quantified. Results show that peach and plum juice consumption protected against a combination of obesity-induced metabolic disorders including hyperglycemia, insulin and leptin resistance, dyslipidemia and low-density lipoprotein oxidation. This was accompanied by a decreased expression of pro-atherogenic and pro-inflammatory biomarkers in plasma and heart tissues including intercellular cell adhesion molecule-1, monocyte chemotactic protein-1, NF-κB and foam cell adherence to aortic arches. In addition, peach and plum juice consumption decreased the levels of angiotensin II in plasma and its receptor Agtr1 in heart tissues, suggesting a role of peach and plum polyphenols as peroxisome proliferator-activated receptor-γ agonists. Furthermore, only plum juice significantly prevented body weight gain and increased the ratio high-density lipoprotein cholesterol/total cholesterol in plasma. This effect is most likely attributed to the plum's higher content of polyphenols (three times that of peach). Altogether, these results imply that cardioprotective effects can be achieved by replacing drinks high in sugar content with fruit juice rich in polyphenols in a diet.

Mechanisms of obesity-induced gastrointestinal neoplasia

Obesity is among the fastest growing diseases worldwide; treatment is inadequate, and associated disorders, including gastrointestinal cancers, have high morbidity and mortality. An increased understanding of the mechanisms of obesity-induced carcinogenesis is required to develop methods to prevent or treat these cancers. In this report, we review the mechanisms of obesity-associated colorectal, esophageal, gastric, and pancreatic cancers and potential treatment strategies.

Prediabetic changes in gene expression induced by aspartame and monosodium glutamate in Trans fat-fed C57Bl/6 J mice

BACKGROUND

The human diet has altered markedly during the past four decades, with the introduction of Trans hydrogenated fat, which extended the shelf-life of dietary oils and promoted a dramatic increase in elaidic acid (Trans-18.1) consumption. Food additives such as monosodium glutamate (MSG) and aspartame (ASP) were introduced to increase food palatability and reduce caloric intake. Nutrigenomics studies in small-animal models are an established platform for analyzing the interactions between various macro- and micronutrients. We therefore investigated the effects of changes in hepatic and adipose tissue gene expression induced by the food additives ASP, MSG or a combination of both additives in C57Bl/6 J mice fed a Trans fat-enriched diet.

METHODS

Hepatic and adipose tissue gene expression profiles, together with body characteristics, glucose parameters, serum hormone and lipid profiles were examined in C57Bl/6 J mice consuming one of the following four dietary regimens, commencing in utero via the mother's diet: [A] Trans fat (TFA) diet; [B] MSG + TFA diet; [C] ASP + TFA diet; [D] ASP + MSG + TFA diet.

RESULTS

Whilst dietary MSG significantly increased hepatic triglyceride and serum leptin levels in TFA-fed mice, the combination of ASP + MSG promoted the highest increase in visceral adipose tissue deposition, serum free fatty acids, fasting blood glucose, HOMA-IR, total cholesterol and TNFα levels. Microarray analysis of significant differentially expressed genes (DEGs) showed a reduction in hepatic and adipose tissue PPARGC1a expression concomitant with changes in PPARGC1a-related functional networks including PPARα, δ and γ. We identified 73 DEGs common to both adipose and liver which were upregulated by ASP + MSG in Trans fat-fed mice; and an additional 51 common DEGs which were downregulated.

CONCLUSION

The combination of ASP and MSG may significantly alter adiposity, glucose homeostasis, hepatic and adipose tissue gene expression in TFA-fed C57Bl/6 J mice.