Histone modifications influence the insulin-signaling genes and are related to insulin resistance in human adipocytes

Adipokines and Adipose Tissue: The Role and Use of Sodium-Glucose Co-Transporter-2 (SGLT-2) Inhibitors in Patients with Diabetes or Heart Failure

Sodium-glucose co-transporter-2 (SGLT-2) inhibitors have become integral in treating both diabetes mellitus and heart failure, independent of left ventricular ejection fraction. Their pleiotropic effect influences multiple mechanisms, enhancing the function of various systems within the body. They exhibit nephroprotective and cardioprotective effects by improving cell metabolism, endothelial function, and slowing the fibrosis of the cardiac muscle, and they also have a beneficial impact on other organs. At the cellular level, they protect against the harmful effects of free radicals both by lowering glucose levels and by supporting the function of the antioxidant system. Moreover, SGLT-2 inhibitors can modify the metabolism of adipocytes by affecting the production of cytokines such as adiponectin-which increases insulin sensitivity, leading to weight loss and improved glycemic control.

Depot-specific acetylation profiles of adipose tissues-therapeutic targets for metabolically unhealthy obesity

BACKGROUND

Adipose tissue plays a critical role in the development of metabolically unhealthy obesity (MUO), with distinct adipose depots demonstrating functional differences. This study aimed to investigate the unique characteristics of subcutaneous (SA) and visceral adipose tissue (VA) in MUO.

METHODS

Paired omental VA and abdominal SA samples were obtained from four male patients with MUO and subjected to Four-Dimensional Data Independent Acquisition (4D-DIA) proteomic and lysine acetylation (Kac) analyses. Differentially expressed proteins and differentially modified Kac sites were identified, quantified, integrated, and subjected to functional analyses. Overlap analysis was performed between our datasets and previously published proteomic datasets in obesity populations. Additionally, differentially modified Kac sites on histones and their related enzymes were identified.

RESULTS

A total of 281 differentially expressed proteins and 147 differentially modified Kac sites were identified among 6,201 quantifiable proteins and 1,826 quantifiable Kac sites. Upregulated proteins and acetylated proteins in SA were predominantly enriched in extracellular matrix (ECM) remodeling pathways, while those in VA were enriched in energy metabolism and disease-related pathways. Differential ECM remodeling adaptability between SA and VA was primarily mediated by fibranexin and integrin, with COL6A1, COL6A3, and ITGA5 identified as differentially acetylated proteins overlapping between our dataset and previous studies. Potential unique proteins in MUO were enriched in inflammatory processes and closely associated with acetylated modifications. Specific differentially acetylated sites on histones, including H1.2K63, H1XK90, and H3.7K80, showed increased acetylation in VA, with N-deacetylase/N-sulfotransferase 1 (NDST1) identified as the associated enzyme.

CONCLUSIONS

This study provided a comprehensive dataset on the proteomic and acetylomic profiles of SA and VA, laying a foundation for investigating the pathogenesis and potential therapeutic approaches for MUO. SA was characterized by pronounced ECM remodeling regulation, while VA exhibited poorer adaptability and more prominent metabolic functional changes. These differential processes were influenced not only by protein expression levels but, more importantly, by acetylated modifications. The regulation of acetylated modifications in white adipose tissue (WAT), particularly for the differential Kac sites enriched in ECM remodeling and inflammation-related pathways, may serve as an effective intervention strategy for MUO, with NDST1 emerging as a promising therapeutic target.

TRIAL REGISTRATION

Not applicable since this study did not involve clinical intervention.

Oyster Mushroom (Pleurotus ostreatus) Ethanolic Extract Inhibits Pparg Expression While Maintaining the Methylation of the Pparg Promoter During 3T3-L1 Adipocyte Differentiation

Purpose

This study aims to provide new insights into the potential of oyster mushroom (Pleurotus ostreatus) ethanolic extract in preventing obesity through the inhibition of Pparg expression and modulation of methylation level on Pparg promoter during 3T3-L1 adipocyte differentiation.

Methods

This in vitro quantitative experimental study was conducted by treating the 3T3-L1 cell line differentiated using 0.5 mM methyl-isobutyl-xanthine, 1 μM dexamethasone, and 10 μg/mL insulin-containing medium with oyster mushroom ethanolic extract. The extract was obtained from 80 g of dried oyster mushroom powder extracted three times with 800 mL of ethanol, filtered, evaporated, and reconstituted in dimethyl sulfoxide (DMSO) to final concentrations of 0, 25, 50, and 100 µg/mL, with DMSO limited to 0.5% in all solutions. Pparg mRNA expression was quantified by qRT-PCR analysis and Pparg promoter methylation levels were measured quantitatively by pyrosequencing of bisulfite-treated DNA samples.

Results

The addition of 25 µg/mL oyster mushroom ethanolic extract significantly suppressed Pparg mRNA expression with no significant change in the Pparg promoter methylation levels.

Conclusion

Oyster mushroom ethanolic extract inhibited Pparg mRNA expression without altering Pparg promoter methylation, suggesting reduced adipocyte differentiation. This study emphasizes the potential of oyster mushroom in the prevention or treatment of obesity by inhibiting adipocyte differentiation.

Exploring PPAR Gamma and PPAR Alpha's Regulation Role in Metabolism via Epigenetics Mechanism

Peroxisome proliferator-activated receptors (PPARs) belong to a family of nuclear receptors. To date, three types of PPARs, namely PPARα, PPARδ, and PPARγ, have been identified, demonstrating co-expression across numerous tissues. PPARγ is primarily distributed in adipose tissue, the colon, the immune system, and the retina, while PPARα is predominantly expressed in metabolic tissues such as brown adipose tissue, the liver, and the kidneys. Both PPARγ and PPARα play crucial roles in various cellular processes. Recent data suggest that the PPAR family, among other mechanisms, might also be regulated by epigenetic mechanisms. Our recent studies, alongside numerous others, have highlighted the pivotal roles of DNA methylation and histone modifications in the regulation of PPARγ and PPARα, implicating them in the deterioration of metabolic disorders via epigenetic mechanisms. This still not fully understood mechanism of regulation in the nuclear receptors family has been summarized and described in the present paper. The present review summarizes the available data on PPARγ and PPARα regulation via epigenetic mechanisms, elucidating the link between the development of metabolic disorders and the dysregulation of PPARγ and PPARα resulting from these mechanisms.

TNF-α/Stearate Induced H3K9/18 Histone Acetylation Amplifies IL-6 Expression in 3T3-L1 Mouse Adipocytes

Extensive evidence supports the connection between obesity-induced inflammation and the heightened expression of IL-6 adipose tissues. However, the mechanism underlying the IL-6 exacerbation in the adipose tissue remains unclear. There is general agreement that TNF-α and stearate concentrations are mildly elevated in adipose tissue in the state of obesity. We hypothesize that TNF-α and stearate co-treatment induce the increased expression of IL-6 in mouse adipocytes. We therefore aimed to determine IL-6 gene expression and protein production by TNF-α/stearate treated adipocytes and investigated the mechanism involved. To test our hypothesis, 3T3-L1 mouse preadipocytes were treated with TNF-α, stearate, or TNF-α/stearate. IL-6 gene expression was assessed by quantitative real-time qPCR. IL-6 protein production secreted in the cell culture media was determined by ELISA. Acetylation of histone was analyzed by Western blotting. Il6 region-associated histone H3 lysine 9/18 acetylation (H3K9/18Ac) was determined by ChIP-qPCR. 3T3-L1 mouse preadipocytes were co-challenged with TNF-α and stearate for 24 h, which led to significantly increased IL-6 gene expression (81 ± 2.1 Fold) compared to controls stimulated with either TNF-α (38 ± 0.5 Fold; p = 0.002) or stearate (56 ± 2.0 Fold; p = 0.013). As expected, co-treatment of adipocytes with TNF-α and stearate significantly increased protein production (338 ± 11 pg/mL) compared to controls stimulated with either TNF-α (28 ± 0.60 pg/mL; p = 0.001) or stearate (53 ± 0.20 pg/mL, p = 0.0015). Inhibition of histone acetyltransferases (HATs) with anacardic acid or curcumin significantly reduced the IL-6 gene expression and protein production by adipocytes. Conversely, TSA-induced acetylation substituted the stimulatory effect of TNF-α or stearate in their synergistic interaction for driving IL-6 gene expression and protein production. Mechanistically, TNF-α/stearate co-stimulation increased the promoter-associated histone H3 lysine 9/18 acetylation (H3K9/18Ac), rendering a transcriptionally permissive state that favored IL-6 expression at the transcriptional and translational levels. Our data represent a TNF-α/stearate cooperativity model driving IL-6 expression in 3T3-L1 cells via the H3K9/18Ac-dependent mechanism, with implications for adipose IL-6 exacerbations in obesity.

Epigenetic regulation of inflammation in insulin resistance

Epigenetics focuses on the study of changes in gene expression based on modifications that do not interfere with the DNA sequence, such as DNA methylation, post-translational histone modification, and non-coding RNA. Epigenetic changes regulate the expression of many genes, including inflammatory ones. Chronic inflammation is often accompanied by insulin resistance (IR), which is characteristic of inter alia type 2 diabetes. Recently, it has been reported that altered epigenetic signature in the promoter regions of inflammatory genes may contribute to the development of IR. Therefore, the aim of this review is to present the current state of knowledge regarding the epigenetic regulation of inflammation in IR. It includes original papers published from 2014 to 2022. It appears that hypomethylation of the SOCS3 gene increases the risk of IR, while the alteration of H3K4me in the NF-kB promoter promotes changes in inflammatory phenotype. Finally, in hyperglycemic states associated with IR, altered levels of H3K4/K9m3 and H3K9/K14ac result in increased expression of the inflammatory cytokine IL-6. In addition, numerous miRNAs have been identified that may become a target in the fight against diseases related to inflammation and IR. Future studies should examine the epigenetic modifications of IR inflammatory markers associated with environmental factors.

360-Degree Perspectives on Obesity

Alarming statistics show that the number of people affected by excessive weight has surpassed 2 billion, representing approximately 30% of the world's population. The aim of this review is to provide a comprehensive overview of one of the most serious public health problems, considering that obesity requires an integrative approach that takes into account its complex etiology, including genetic, environmental, and lifestyle factors. Only an understanding of the connections between the many contributors to obesity and the synergy between treatment interventions can ensure satisfactory outcomes in reducing obesity. Mechanisms such as oxidative stress, chronic inflammation, and dysbiosis play a crucial role in the pathogenesis of obesity and its associated complications. Compounding factors such as the deleterious effects of stress, the novel challenge posed by the obesogenic digital (food) environment, and the stigma associated with obesity should not be overlooked. Preclinical research in animal models has been instrumental in elucidating these mechanisms, and translation into clinical practice has provided promising therapeutic options, including epigenetic approaches, pharmacotherapy, and bariatric surgery. However, more studies are necessary to discover new compounds that target key metabolic pathways, innovative ways to deliver the drugs, the optimal combinations of lifestyle interventions with allopathic treatments, and, last but not least, emerging biological markers for effective monitoring. With each passing day, the obesity crisis tightens its grip, threatening not only individual lives but also burdening healthcare systems and societies at large. It is high time we took action as we confront the urgent imperative to address this escalating global health challenge head-on.

Epigenetics of the Pathogenesis and Complications of Type 2 Diabetes Mellitus

Epigenetics of type 2 diabetes mellitus (T2DM) has widened our knowledge of various aspects of the disease. The aim of this review is to summarize the important epigenetic changes implicated in the disease risks, pathogenesis, complications and the evolution of therapeutics in our current understanding of T2DM. Studies published in the past 15 years, from 2007 to 2022, from three primary platforms namely PubMed, Google Scholar and Science Direct were included. Studies were searched using the primary term 'type 2 diabetes and epigenetics' with additional terms such as 'risks', 'pathogenesis', 'complications of diabetes' and 'therapeutics'. Epigenetics plays an important role in the transmission of T2DM from one generation to another. Epigenetic changes are also implicated in the two basic pathogenic components of T2DM, namely insulin resistance and impaired insulin secretion. Hyperglycaemia-i nduced permanent epigenetic modifications of the expression of DNA are responsible for the phenomenon of metabolic memory. Epigenetics influences the development of micro-and macrovascular complications of T2DM. They can also be used as biomarkers in the prediction of these complications. Epigenetics has expanded our understanding of the action of existing drugs such as metformin, and has led to the development of newer targets to prevent vascular complications. Epigenetic changes are involved in almost all aspects of T2DM, from risks, pathogenesis and complications, to the development of newer therapeutic targets.

Unlocking the Full Potential of SGLT2 Inhibitors: Expanding Applications beyond Glycemic Control

The number of diabetic patients has risen dramatically in recent decades, owing mostly to the rising incidence of type 2 diabetes mellitus (T2DM). Several oral antidiabetic medications are used for the treatment of T2DM including, α-glucosidases inhibitors, biguanides, sulfonylureas, meglitinides, GLP-1 receptor agonists, PPAR-γ agonists, DDP4 inhibitors, and SGLT2 inhibitors. In this review we focus on the possible effects of SGLT2 inhibitors on different body systems. Beyond the diabetic state, SGLT2 inhibitors have revealed a demonstrable ability to ameliorate cardiac remodeling, enhance myocardial function, and lower heart failure mortality. Additionally, SGLT2 inhibitors can modify adipocytes and their production of cytokines, such as adipokines and adiponectin, which enhances insulin sensitivity and delays diabetes onset. On the other hand, SGLT2 inhibitors have been linked to decreased total hip bone mineral deposition and increased hip bone resorption in T2DM patients. More data are needed to evaluate the role of SGLT2 inhibitors on cancer. Finally, the effects of SGLT2 inhibitors on neuroprotection appear to be both direct and indirect, according to scientific investigations utilizing various experimental models. SGLT2 inhibitors improve vascular tone, elasticity, and contractility by reducing oxidative stress, inflammation, insulin signaling pathways, and endothelial cell proliferation. They also improve brain function, synaptic plasticity, acetylcholinesterase activity, and reduce amyloid plaque formation, as well as regulation of the mTOR pathway in the brain, which reduces brain damage and cognitive decline.

The Emerging Role of Epigenetics in Metabolism and Endocrinology

Each cell in a multicellular organism has its own phenotype despite sharing the same genome. Epigenetics is a somatic, heritable pattern of gene expression or cellular phenotype mediated by structural changes in chromatin that occur without altering the DNA sequence. Epigenetic modification is an important factor in determining the level and timing of gene expression in response to endogenous and exogenous stimuli. There is also growing evidence concerning the interaction between epigenetics and metabolism. Accordingly, several enzymes that consume vital metabolites as substrates or cofactors are used during the catalysis of epigenetic modification. Therefore, altered metabolism might lead to diseases and pathogenesis, including endocrine disorders and cancer. In addition, it has been demonstrated that epigenetic modification influences the endocrine system and immune response-related pathways. In this regard, epigenetic modification may impact the levels of hormones that are important in regulating growth, development, reproduction, energy balance, and metabolism. Altering the function of the endocrine system has negative health consequences. Furthermore, endocrine disruptors (EDC) have a significant impact on the endocrine system, causing the abnormal functioning of hormones and their receptors, resulting in various diseases and disorders. Overall, this review focuses on the impact of epigenetics on the endocrine system and its interaction with metabolism.

Epigenetics and mitochondrial dysfunction insights into the impact of the progression of non-alcoholic fatty liver disease

A metabolic problem occurs when regular functions of the body are disrupted due to an undesirable imbalance. Nonalcoholic fatty liver disease (NAFLD) is considered as one of the most common in this category. NAFLD is subclassified and progresses from lipid accumulation to cirrhosis before advancing to hepatocellular cancer. In spite of being a critical concern, the standard treatment is inadequate. Metformin, silymarin, and other nonspecific medications are used in the management of NAFLD. Aside from this available medicine, maintaining a healthy lifestyle has been emphasized as a means of combating this. Epigenetics, which has been attributed to NAFLD, is another essential feature of this disease that has emerged as a result of several sorts of research. The mechanisms by which DNA methylation, noncoding RNA, and histone modification promote NAFLD have been extensively researched. Another organelle, mitochondria, which play a pivotal role in biological processes, contributes to the global threat. Individuals with NAFLD have been documented to have a multitude of alterations and malfunctioning. Mitochondria are mainly concerned with the process of energy production and regulation of the signaling pathway on which the fate of a cell relies. Modulation of mitochondria leads to elevated lipid deposition in the liver. Further, changes in oxidation states result in an impaired balance between the antioxidant system and reactive oxygen species directly linked to mitochondria. Hence mitochondria have a definite role in potentiating NAFLD. In this regard, it is essential to consider the role of epigenetics as well as mitochondrial contribution while developing a medication or therapy with the desired accuracy.

Recent progress in epigenetics of obesity

Nowadays, obesity is one of the largest public health problems worldwide. In the last few decades, there has been a marked increase in the obesity epidemic and its related comorbidities. Worldwide, more than 2.2 billion people (33%) are affected by overweight or obesity (712 million, 10%) and its associated metabolic complications. Although a high heritability of obesity has been estimated, the genetic variants conducted from genetic association studies only partially explain the variation of body mass index. This has led to a growing interest in understanding the potential role of epigenetics as a key regulator of gene-environment interactions on the development of obesity and its associated complications. Rapid advances in epigenetic research methods and reduced costs of epigenome-wide association studies have led to a great expansion of population-based studies. The field of epigenetics and metabolic diseases such as obesity has advanced rapidly in a short period of time. The main epigenetic mechanisms include DNA methylation, histone modifications, microRNA (miRNA)-mediated regulation and so on. DNA methylation is the most investigated epigenetic mechanism. Preliminary evidence from animal and human studies supports the effect of epigenetics on obesity. Studies of epigenome-wide association studies and genome-wide histone modifications from different biological specimens such as blood samples (newborn, children, adolescent, youth, woman, man, twin, race, and meta-analysis), adipose tissues, skeletal muscle cells, placenta, and saliva have reported the differential expression status of multiple genes before and after obesity interventions and have identified multiple candidate genes and biological markers. These findings may improve the understanding of the complex etiology of obesity and its related comorbidities, and help to predict an individual's risk of obesity at a young age and open possibilities for introducing targeted prevention and treatment strategies.

Trends in insulin resistance: insights into mechanisms and therapeutic strategy

The centenary of insulin discovery represents an important opportunity to transform diabetes from a fatal diagnosis into a medically manageable chronic condition. Insulin is a key peptide hormone and mediates the systemic glucose metabolism in different tissues. Insulin resistance (IR) is a disordered biological response for insulin stimulation through the disruption of different molecular pathways in target tissues. Acquired conditions and genetic factors have been implicated in IR. Recent genetic and biochemical studies suggest that the dysregulated metabolic mediators released by adipose tissue including adipokines, cytokines, chemokines, excess lipids and toxic lipid metabolites promote IR in other tissues. IR is associated with several groups of abnormal syndromes that include obesity, diabetes, metabolic dysfunction-associated fatty liver disease (MAFLD), cardiovascular disease, polycystic ovary syndrome (PCOS), and other abnormalities. Although no medication is specifically approved to treat IR, we summarized the lifestyle changes and pharmacological medications that have been used as efficient intervention to improve insulin sensitivity. Ultimately, the systematic discussion of complex mechanism will help to identify potential new targets and treat the closely associated metabolic syndrome of IR.

The metabolic syndrome, thiazolidinediones, and implications for intersection of chronic and inflammatory disease

BACKGROUND

Chronic disease appears connected to obesity. However, evidence suggests that chronic metabolic diseases are more specifically related to adipose dysfunction rather than to body weight itself.

SCOPE OF REVIEW

Further study of the first generation "insulin sensitizer" pioglitazone and molecules based on its structure suggests that is possible to decouple body weight from the metabolic dysfunction that drives adverse outcomes. The growing understanding of the mechanism of action of these agents together with advances in the pathophysiology of chronic metabolic disease offers a new approach to treat chronic conditions, such as type 2 diabetes, fatty liver disease, and their common organ and vascular sequelae.

MAJOR CONCLUSIONS

We hypothesize that treating adipocyte dysfunction with new insulin sensitizers might significantly impact the interface of infectious disease and chronic metabolic disease.