Disruption Of Insulin Signaling Research Articles

Activation of the De Novo Serine Synthesis Pathway and Disruption of Insulin Signaling Induced by Supplemental SeMet in Vitro.

Selenium (Se) intake or selenoprotein overexpression can cause abnormal glucose metabolism and increase the risk of type 2 diabetes (T2D). The purpose of this study is to observe whether glycolysis bypass in the de novo serine synthesis pathway (SSP) is activated under high-Se stress in vitro. Initially, HCT-116, L02, HepG2, and differentiated C2C12 cells were exposed to five selenomethionine (SeMet) concentrations (0.001 to 10µmol/L) for 48h. The expressions of glutathione peroxidase 1 (GPX1), selenoprotein P (SELENOP), 3-phosphoglycerate dehydrogenase (PHGDH), and serine hydroxy-methyltransferases 1 (SHMT1) were assessed by western blotting (WB). Then, corresponding to the peak expressions of GPX1, SELENOP, and PHGDH, 0.1µmol/L SeMet was identified as the highest intervention concentration. With more detailed levels of SeMet (0.001 to 0.1µmol/L) given, the differentiated C2C12 cells were treated for 48h to analyze the expressions of selenoproteins, enzymes related with serine metabolism and insulin signaling pathway. Among the four cell lines, the expressions of selenoproteins and metabolic enzymes of serine in C2C12 cells were more sensitive to changes in Se concentrations, which was similar to that in L02 cells. In C2C12 cells, the expressions of GPX1, SELENOP, selenoprotein N (SELENON), PHGDH, and SHMT1 exhibited a parabolic inflection point at SeMet concentrations of 0.05µmol/L or 0.075µmol/L, while 5,10-methylenetetrahydrofolate reductase (MTHFR) and methionine synthase (MS) showed no such trend. After 15min of insulin stimulation, glucose retained more in the culture medium due to the decreased uptake by C2C12 cells. The expressions of key enzymes (AKT, AKT (Ser-473), AKT (Thr-308), mTOR, and PI3K) in the PI3K-AKT-mTOR signaling pathway decreased with the increased level of SeMet. This study demonstrated that excessive Se intake could induce abnormal glucose metabolism via SSP and impair the normal signaling of insulin in the differentiated C2C12 cells.

The Role of Beta-Hydroxybutyrate in Mitigating the Inflammatory and Metabolic Consequences of Uric Acid.

Background: Uric acid (UA), a metabolite of purine and fructose metabolism, is linked to inflammation and metabolic disorders, including gout and cardiovascular disease. Its pro-inflammatory effects are largely driven by the activation of the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, leading to increased cytokine production. Beta-hydroxybutyrate (BHB), a ketone produced during fasting or carbohydrate restriction, has been shown to reduce inflammation. This study explores the role of BHB in mitigating the inflammatory and metabolic effects of elevated uric acid levels. Methods: We utilized a murine muscle cell culture treated with UA and BHB. Results: Muscle cells treated with UA had increased production of pro-inflammatory cytokines and reduced cell viability. Co-treatment with BHB reversed these effects, improving cell survival and reducing cytokine levels. Additionally, uric acid impaired mitochondrial function and increased oxidative stress, which were mitigated by BHB. Furthermore, uric acid disrupted insulin signaling, but BHB co-treatment restored insulin sensitivity. Conclusions: These findings suggest that BHB holds therapeutic potential by counteracting the inflammatory and metabolic disruptions caused by elevated uric acid, making it a promising target for conditions such as hyperuricemia and metabolic syndrome.

Cellular and Molecular Pathophysiology of Gestational Diabetes.

Gestational diabetes (GD) is a metabolic disorder characterized by glucose intolerance during pregnancy, significantly impacting maternal and fetal health. Its global prevalence is approximately 14%, with risk factors including obesity, family history of diabetes, advanced maternal age, and ethnicity, which are linked to cellular and molecular disruptions in glucose regulation and insulin resistance. GD is associated with short- and long-term complications for both the mother and the newborn. For mothers, GD increases the risk of developing type 2 diabetes, cardiovascular diseases, and metabolic syndrome. In the offspring, exposure to GD in utero predisposes them to obesity, glucose intolerance, and metabolic disorders later in life. This review aims to elucidate the complex cellular and molecular mechanisms underlying GD to inform the development of effective therapeutic strategies. A systematic review was conducted using medical subject headings (MeSH) terms related to GD's cellular and molecular pathophysiology. Inclusion criteria encompassed original studies, systematic reviews, and meta-analyses focusing on GD's impact on maternal and fetal health, adhering to PRISMA guidelines. Data extraction captured study characteristics, maternal and fetal outcomes, key findings, and conclusions. GD disrupts insulin signaling pathways, leading to impaired glucose uptake and insulin resistance. Mitochondrial dysfunction reduces ATP production and increases reactive oxygen species, exacerbating oxidative stress. Hormonal influences, chronic inflammation, and dysregulation of the mammalian target of rapamycin (mTOR) pathway further impair insulin signaling. Gut microbiota alterations, gene expression, and epigenetic modifications play significant roles in GD. Ferroptosis and placental dysfunction primarily contribute to intrauterine growth restriction. Conversely, fetal macrosomia arises from maternal hyperglycemia and subsequent fetal hyperinsulinemia, resulting in excessive fetal growth. The chronic inflammatory state and oxidative stress associated with GD exacerbate these complications, creating a hostile intrauterine environment. GD's complex pathophysiology involves multiple disruptions in insulin signaling, mitochondrial function, inflammation, and oxidative stress. Effective management requires early detection, preventive strategies, and international collaboration to standardize care and improve outcomes for mothers and babies.

Discovery of Novel PTP1B Inhibitors by High-throughput Virtual Screening.

To Discover novel PTP1B inhibitors by high-throughput virtual screening Background: Type 2 Diabetes is a significant global health concern. According to projections, the estimated number of individuals affected by the condition will reach 578 million by the year 2030 and is expected to further increase to 700 million deaths by 2045. Protein Tyrosine Phosphatase 1B is an enzymatic protein that has a negative regulatory effect on the pathways involved in insulin signaling. This regulatory action ultimately results in the development of insulin resistance and the subsequent elevation of glucose levels in the bloodstream. The proper functioning of insulin signaling is essential for maintaining glucose homeostasis, whereas the disruption of insulin signaling can result in the development of type 2 diabetes. Consequently, we sought to utilize PTP1B as a drug target in this investigation. The purpose of our study was to identify novel PTP1B inhibitors as a potential treatment for managing type 2 diabetes. To discover potent PTP1B inhibitors, we have screened the Maybridge HitDiscover database by SBVS. Top hits have been passed based on various drug-likeness rules, toxicity predictions, ADME assessment, Consensus Molecular docking, DFT, and 300 ns MD Simulations. Two compounds have been identified with strong binding affinity at the active site of PTP1B along with drug-like properties, efficient ADME, low toxicity, and high stability. The identified molecules could potentially manage T2DM effectively by inhibiting PTP1B, providing a promising avenue for therapeutic strategies.

Impact of Lipids on Insulin Resistance: Insights from Human and Animal Studies.

Insulin resistance (IR) is a complex pathological condition central to metabolic diseases such as type 2 diabetes mellitus (T2DM), cardiovascular disease, non-alcoholic fatty liver disease, and polycystic ovary syndrome (PCOS). This review evaluates the impact of lipids on insulin resistance (IR) by analyzing findings from human and animal studies. The articles were searched on the PubMed database using two keywords: (1) "Role of Lipids AND Insulin Resistance AND Humans" and (2) "Role of Lipids AND Insulin Resistance AND Animal Models". Studies in humans revealed that elevated levels of free fatty acids (FFAs) and triglycerides (TGs) are closely associated with reduced insulin sensitivity, and interventions like metformin and omega-3 fatty acids show potential benefits. In animal models, high-fat diets disrupt insulin signaling and increase inflammation, with lipid mediators such as diacylglycerol (DAG) and ceramides playing significant roles. DAG activates protein kinase C, which eventually impairs insulin signaling, while ceramides inhibit Akt/PKB, further contributing to IR. Understanding these mechanisms is crucial for developing effective prevention and treatment strategies for IR-related diseases.

Deciphering molecular bridges: Unveiling the interplay between metabolic syndrome and Alzheimer's disease through a systems biology approach and drug repurposing.

The association between Alzheimer's disease and metabolic disorders as significant risk factors is widely acknowledged. However, the intricate molecular mechanism intertwining these conditions remains elusive. To address this knowledge gap, we conducted a thorough investigation using a bioinformatics method to illuminate the molecular connections and pathways that provide novel perspectives on these disorders' pathological and clinical features. Microarray datasets (GSE5281, GSE122063) from the Gene Expression Omnibus (GEO) database facilitated the way to identify genes with differential expression in Alzheimer's disease (141 genes). Leveraging CoreMine, CTD, and Gene Card databases, we extracted genes associated with metabolic conditions, including hypertension, non-alcoholic fatty liver disease, and diabetes. Subsequent analysis uncovered overlapping genes implicated in metabolic conditions and Alzheimer's disease, revealing shared molecular links. We utilized String and HIPPIE databases to visualize these shared genes' protein-protein interactions (PPI) and constructed a PPI network using Cytoscape and MCODE plugin. SPP1, CD44, IGF1, and FLT1 were identified as crucial molecules in the main cluster of Alzheimer's disease and metabolic syndrome. Enrichment analysis by the DAVID dataset was employed and highlighted the SPP1 as a novel target, with its receptor CD44 playing a significant role in the inflammatory cascade and disruption of insulin signaling, contributing to the neurodegenerative aspects of Alzheimer's disease. ECM-receptor interactions, focal adhesion, and the PI3K/Akt pathways may all mediate these effects. Additionally, we investigated potential medications by repurposing the molecular links using the DGIdb database, revealing Tacrolimus and Calcitonin as promising candidates, particularly since they possess binding sites on the SPP1 molecule. In conclusion, our study unveils crucial molecular bridges between metabolic syndrome and AD, providing insights into their pathophysiology for therapeutic interventions.

237 Disrupted insulin signaling due to an acute immune response in swine

Abstract Insulin is an anabolic hormone involved in glucose uptake and synthesis of fats, proteins, and glycogen. Altered insulin signaling can occur due to metabolic state, pathogen exposure, and autoimmune disorders. Lipopolysaccharide (LPS), an endotoxin secreted produced by gram-negative bacteria, can induce a severe, systemic immune response. In pigs, chronic LPS exposure has induced insulin resistance. However, the effects of acute exposure to LPS on insulin signaling and resistance have not been elucidated. Crossbred nursery pigs [n = 58, initial body weight (BW) = 12.1 kg ± 0.23 kg] were randomly assigned into two experimental subsets, where 10 animals were designated for repeated blood sampling and 48 animals underwent timed euthanasia for tissue collection. For repeated blood sampling, jugular catheters were placed under anesthesia and the animals were given 48 h to recover before being randomly assigned to treatments. These treatments were an intraperitoneal injection of either 15µg/kg BW LPS or an equal volume of 0.9% Saline (n = 5 pigs/treatment). Blood was collected for 48 h followed by euthanasia. The other 48 pigs were randomly assigned to the same treatments, and then randomly assigned to euthanasia timepoints of 0, 3, 6, 12, 24 or 48 h post injection for tissue collection. Among the catheterized pigs, 2-h post LPS challenge there was a decrease in serum insulin concentration (P < 0.05) and mild hyperglycemia (P < 0.05) post challenge. At 12- and 24-h post LPS challenge there was a decrease in insulin (P < 0.05) and a trend hyperglycemia was also apparent at 24 h (P = 0.063). In liver tissue, insulin related genes exhibited alterations post LPS injection. Phosphoinositide 3-kinase (pi3k) and insulin receptor substrate 1 (irs1) expression were decreased at 3 and 6 h (p< 0.05) and protein kinase b (akt) expression were decreased at 3 h (P < 0.05) post challenge. The expression of insulin inhibitor growth factor receptor bound protein 10 (grb10) was decreased at 6-, 12-, and 24-h after challenge (P < 0.05). Fructose-1-6-bisphosphatase (f16bp) expression was reduced at 3-, 6-, and 12-h (P < 0.05) in the liver while phosphoenolpyruvate carboxykinase (pepck) expression was decreased at 3- and 6-h (P < 0.01) post challenge. Other metabolic genes were decreased at 3-, 6-, and 12-h post LPS challenge, including fatty acid synthase (fas; P < 0.05), carbohydrate response element binding protein (chrebp; P < 0.05), and acetyl CoA carboxylase (acc; P < 0.05). Protein abundance of Akt 3 h after LPS injection was decreased in the liver (P < 0.05). In skeletal muscle 6 h post LPS injection, insulin receptor (insr), insulin-like growth factor receptor (igfr) and fas were all increased (P < 0.05) These results indicate disrupted insulin signaling at various levels after an acute immune response.

Disrupted Insulin Signaling Due to an Acute Immune Response in Swine

Insulin is an anabolic hormone involved in glucose uptake and synthesis of fats, proteins, and glycogen. Altered insulin signaling can occur due to metabolic state, pathogen exposure, and autoimmune disorders. Lipopolysaccharide (LPS), an endotoxin secreted produced by gram-negative bacteria, can induce a severe, systemic immune response. In pigs, chronic LPS exposure has induced insulin resistance. However, the effects of acute exposure to LPS on insulin signaling and resistance has not been elucidated. Crossbred nursery pigs (58, 12.1 kg ± 0.23kg BW) were randomly assigned into two experimental subsets, where 10 animals were designated for repeated blood sampling and 48 animals underwent timed euthanasia for tissue collection. For repeated blood sampling, jugular catheters were placed under anesthesia and the animals were given 48 hours to recover before being randomly assigned to treatments. These treatments were an intraperitoneal injection of either 15μg/kg BW LPS or an equal volume of 0.9% Saline (n=5 pigs/treatment). Blood was collected for 48 hours followed by euthanasia. The other 48 pigs were randomly assigned to the same treatments, and then randomly assigned to euthanasia timepoints of 0, 3, 6, 12, 24 or 48 hours post injection for tissue collection. Among the catheterized pigs, two hours post LPS challenge there was a decrease in serum insulin concentration (p<0.05) and mild hyperglycemia (p<0.05) post challenge. At 12 and 24 hours post LPS challenge there was a decrease in insulin (p<0.05) and a trend hyperglycemia was also apparent at 24 hours (p=0.063). In liver tissue, insulin related genes exhibited alterations post LPS injection. Phosphoinositide 3-kinase ( pi3k) and insulin receptor substrate 1 ( irs1) expression were decreased at 3 and 6 hours (p<0.05) and protein kinase b ( akt) expression were decreased at 3 hours (p<0.05) post challenge. The expression of insulin inhibitor growth factor receptor bound protein 10 ( grb10) was decreased at 6, 12, and 24 hours after challenge (p<0.05). Fructose-1-6-bisphosphatase ( f16bp) expression was reduced at 3, 6, and 12 hours (p<0.05) in the liver while phosphoenolpyruvate carboxykinase ( pepck) expression was decreased at 3 and 6 hours (p<0.01) post challenge. Other metabolic genes were decreased at 3, 6, and 12 hours post LPS challenge, including fatty acid synthase ( fas) (p<0.05), carbohydrate response element binding protein ( chrebp) (p<0.05), and acetyl CoA carboxylase ( acc)(p<0.05). Protein abundance of Akt 3 hours after LPS injection was decreased in the liver (p<0.05). In skeletal muscle 6 hours post LPS injection, insulin receptor ( insr), insulin-like growth factor receptor ( igfr) and fas were all increased (p<0.05) These results indicate disrupted insulin signaling at various levels after an acute immune response. Research reported in this abstract was supported by Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD) of the National Institutes of Health under award number R01HD092304A. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

High Fructose Diet (HFrD) Induced Hepatic Insulin Resistance Is Not Present in Liver Androgen Receptor Knockout (LivARKO) Male Mice

Background: Hyperandrogenism (HA), a common symptom of polycystic ovary syndrome (PCOS), involves action of the androgen receptor (AR) and can induce insulin resistance among 35-80% of PCOS women (PMID 35432749: Amisi 2022). The liver plays an essential role in the metabolism of insulin and androgen signaling. HA has been shown to increase insulin resistance in women and female mice. Previous studies have suggested that knocking out liver AR can lead to improvements in metabolic and reproductive functions of PCOS (PMID 34547140: Andrisse 2021). Hypothesis: We hypothesized that liver androgen receptor knockout (LivARKO) mice on a high fructose diet would exhibit increased insulin resistance compared to controls, as measured by expression of phospho-Akt (p-Akt) and phospho-FoxO1 (p-foxo1), proteins involved in insulin signaling. Methods: LivARKO mice were divided into groups based on an assigned diet (Control or High Fructose; Con, Research Diets Inc, RDI D12450J, Protein (20%), Carbs (70%, corn starch-50%, sucrose-maldextrin-20%, fructose-0%), Fat 10% (lard)) and High Fructose (HFrD, RDI D02022704, Protein (20%), Carbs (70%, corn starch-9%, sucrose-maldextrin-1%, fructose-60%), Fat 10% (lard)). The mice were sacrificed and liver tissue samples were extracted for western blotting analysis examining p-Akt S473 and p-foxo1 S256 levels. Results: LivARKO male mice fed the control diet for one month displayed a significant increase in p-AKT expression when stimulated with insulin compared to basal controls. Similarly, LivARKO male mice fed the high fructose diet for one month displayed a significant increase in p-AKT expression when stimulated with insulin compared to basal mice on the same diet. After one month, LivARKO male mice on a control diet stimulated with insulin displayed significantly decreased p-Foxo1 expression compared to non-stimulated basal control. A similar trend was seen between basal and insulin-stimulated groups in the LivARKO-HFrD male mice, though this trend was not significant. Discussion: These findings suggested that the HFrD did not induce hepatic insulin resistance in LivARKO male mice. Here, we observed a similar pattern of increased insulin stimulated p-AKT to what is seen in WT mice on a chow diet (PMCID PMC3296881: Lu 2012); and this suggested that LivARKO did not disrupt insulin signaling in the liver of male mice when fed a control diet, which was similar to what was seen previously (DOI: 10.1002/hep.22252, Lin 2008, insulin increased PI3K activity in chow diet LivARKO male mice). Our data suggested that the HFrD induced hepatic insulin resistance seen in some WT models (such as PMCID PMC3131094: Nagai 2009) is not present in LivARKO male mice.This also suggested that unlike HFD, HFrD did not cause insulin resistance in LivARKO male mice. These results illuminate LivARKO as a potential therapeutic target for insulin resistance. This project was supported by the following grants to Dr. Stanley Andrisse. (1) NIH 1R01DK126892; (2) NIH 1T34GM142610; and (3) NSF 1931045. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effect of Lampaya medicinalis Phil. (Verbenaceae) and Palmitic Acid on Insulin Signaling and Inflammatory Marker Expression in Human Adipocytes.

Aging and obesity are associated with insulin resistance (IR) and low-grade inflammation. Molecularly, IR is characterized by a reduction in glucose uptake and insulin signaling (IRS-1/Akt/AS160 pathway), while inflammation may result from upregulated NF-κB pathway after low Tyr-IκBα phosphorylation. Upregulated phosphatase activity of PTP1B is associated with impaired insulin signaling and increased inflammation. Plasma levels of palmitic acid (PA) are elevated in obesity, triggering inflammation and disruption of insulin signaling. Traditional medicine in Northern Chile uses oral infusions of Lampaya medicinalis Phil. (Verbenaceae) to treat inflammatory conditions. Significant amounts of flavonoids are found in the hydroethanolic extract of Lampaya (HEL), which may account for its biological activity. The aim of this work was to study the effect of HEL and PA on insulin signaling and glucose uptake as well as inflammatory marker expression in human adipocytes. We studied HEL effects on PA-induced impairment on insulin signaling, glucose uptake and inflammatory marker content in human SW872 adipocytes. HEL cytotoxicity was assessed in adipocytes at different concentrations (0.01 to 10 g/mL). Adipocytes were incubated or not with PA (0.4 mM, 24 h) with or without HEL (2 h pre-incubation), and then stimulated with insulin (10 min, 100 mM) or a vehicle. Phospho-IRS-1, phospho-Akt, phospho-AS160, phospho-NF-κB and phospho-IκBα, as well as protein levels of PTP1B, were assessed using Western blotting, and glucose uptake was evaluated using the 2-NBDG analogue. At the assessed HEL concentrations, no cytotoxic effects were observed. PA decreased insulin-stimulated phospho-Akt and glucose uptake, while co-treatment with HEL increased such markers. PA decreased phospho-IRS-1 and phospho-Tyr-IκBα. On the other hand, incubation with HEL+PA decreased phospho-AS160 and phospho-NF-κB compared with cells treated with PA alone. Our results suggest a beneficial effect of HEL by improving PA-induced impairment on molecular markers of insulin signaling, glucose uptake and inflammation in adipocytes. Further studies are necessary to elucidate whether lampaya may constitute a preventive strategy for people whose circulating PA levels contribute to IR and inflammation during aging and obesity.

Mechanism of muscle atrophy in a normal-weight rat model of type 2 diabetes established by using a soft-pellet diet

Dietary factors such as food texture affect feeding behavior and energy metabolism, potentially causing obesity and type 2 diabetes. We previously found that rats fed soft pellets (SPs) were neither hyperphagic nor overweight but demonstrated glucose intolerance, insulin resistance, and hyperplasia of pancreatic β-cells. In the present study, we investigated the mechanism of muscle atrophy in rats that had been fed SPs on a 3-h time-restricted feeding schedule for 24 weeks. As expected, the SP rats were normal weight; however, they developed insulin resistance, glucose intolerance, and fat accumulation. In addition, skeletal muscles of SP rats were histologically atrophic and demonstrated disrupted insulin signaling. Furthermore, we learned that the muscle atrophy of the SP rats developed via the IL-6–STAT3–SOCS3 and ubiquitin–proteasome pathways. Our data show that the dietary habit of consuming soft foods can lead to not only glucose intolerance or insulin resistance but also muscle atrophy.

MODERN VIEWS ON THE PATHOGENESIS OF IMMUNE DYSFUNCTION AGAINST THE BACKGROUND OF THE METABOLIC SYNDROME IN ISCHEMIC HEART DISEASE

Introduction. Today, the pathology of the cardiovascular system is one of the most common and fatal diseases. Cardiovascular diseases are the cause of disability among the younger and younger population. Taking into account the frequency of cardiovascular diseases, the severity of the course and their lethality, the study of this topic remains one of the most urgent problems of medicine, in particular cardiology.
 The aim of the study. Consider modern views on the pathogenesis of coronary heart disease against the background of metabolic syndrome and the role of the immune system.
 Conclusions. Ischemic heart disease is the leading cause of mortality in Ukraine and the world. In recent years, there has been convincing evidence of a significant prevalence of cardiovascular disease in patients with metabolic syndrome. The presence of concomitant metabolic syndrome in patients with coronary heart disease worsens the course of the underlying disease and has an unfavorable prognosis, and even fatal cases.
 Therefore, the detection of an increase in the level of body mass index, dyslipidemia, hyperglycemia, arterial hypertension in a patient strengthens the effects of each other, that is, they have a synergistic effect, and in general, the risk of developing CHD becomes quite high.
 IL-6 is one of the cytokines released by both macrophages and adipocytes and its levels have been shown to be increased in insulin resistance and obesity. In fact, IL-6 is known to regulate fat and glucose metabolism, mediating insulin resistance through various complex mechanisms. This cytokine acts on various tissues, leading to the metabolic effects of obesity. In the liver, IL-6 increases the production of acute phase reactants, including CRP. Several studies have demonstrated that high CRP levels have the strongest correlation with cardiac events, T2DM, and MS. IL-6 also contributes to a prothrombotic state by increasing the level of fibrinogen, another acute phase reactant. In addition, IL-6 targets other tissues, such as endothelial cells, to promote the expression of vascular cell adhesion molecules, leading to vascular wall atherosclerosis, inflammation, and dysfunction.
 These data support the role of IL-6 in the development of insulin resistance, but do not support the hypothesis that IL-6 is involved in β-cell failure.
 IL-18 is a pro-inflammatory cytokine associated with insulin resistance and T2DM risk. IL-18 stimulates the production of gamma interferon (IFN-γ), which, in turn, is probably involved in the pathogenesis of atherosclerosis. IL-18 is a cytokine that is a predictor of metabolic syndrome.
 TNFα is another cytokine produced in adipose tissue, mainly from local macrophages, and its production also varies with adipose tissue mass and correlates with insulin resistance, both hallmarks of MS. TNFα exerts its pathogenic effects by disrupting insulin signaling in adipocytes and hepatocytes through serine phosphorylation and inactivation of insulin receptors and downstream signaling molecules, leading to decreased metabolic effects of insulin. TNFα also contributes to insulin resistance by inducing hepatic lipolysis.

Impact of NLRP3 Depletion on Aging-Related Metaflammation, Cognitive Function, and Social Behavior in Mice

Immunosenescence and chronic inflammation associated with old age accompany brain aging and the loss of complex behaviors. Neuroinflammation in the hippocampus plays a pivotal role in the development of cognitive impairment and anxiety. However, the underlying mechanisms have not been fully explained. In this study, we aimed to investigate the disruption of insulin signaling and the mechanisms underlying metabolic inflammation (“metaflammation”) in the brains of wild-type (WT) and NLRP3 knockout (KO) mice of different ages. We found a significant upregulation of the NLRP3 inflammasome in the hippocampus during aging, leading to an increase in the expression of phosphorylated metaflammation proteinases and inflammatory markers, along with an increase in the number of senescent cells. Additionally, metaflammation causes anxiety and impairs social preference behavior in aged mice. On the other hand, deletion of NLRP3 improves some behavioral and biochemical characteristics associated with aging, such as signal memory, neuroinflammation, and metabolic inflammation, but not anxious behavior. These results are associated with reduced IL-18 signaling and the PKR/IKKβ/IRS1 pathway as well as the SASP phenotype. In NLRP3 gene deletion conditions, PKR is down-regulated. Therefore, it is likely that slowing aging through various NLRP3 inhibition mechanisms will lessen the corresponding cognitive decline with aging. Thus, the genetic knockout of the NLRP3 inflammasome can be seen as a new therapeutic strategy for slowing down central nervous system (CNS) aging.

Polycystic Ovary Syndrome and Oxidative Stress-From Bench to Bedside.

Oxidative stress (OS) is a condition that occurs as a result of an imbalance between the production of reactive oxygen species (ROS) and the body's ability to detoxify and neutralize them. It can play a role in a variety of reproductive system conditions, including polycystic ovary syndrome (PCOS), endometriosis, preeclampsia, and infertility. In this review, we briefly discuss the links between oxidative stress and PCOS. Mitochondrial mutations may lead to impaired oxidative phosphorylation (OXPHOS), decreased adenosine triphosphate (ATP) production, and an increased production of ROS. These functional consequences may contribute to the metabolic and hormonal dysregulation observed in PCOS. Studies have shown that OS negatively affects ovarian follicles and disrupts normal follicular development and maturation. Excessive ROS may damage oocytes and granulosa cells within the follicles, impairing their quality and compromising fertility. Impaired OXPHOS and mitochondrial dysfunction may contribute to insulin resistance (IR) by disrupting insulin signaling pathways and impairing glucose metabolism. Due to dysfunctional OXPHOS, reduced ATP production, may hinder insulin-stimulated glucose uptake, leading to IR. Hyperandrogenism promotes inflammation and IR, both of which can increase the production of ROS and lead to OS. A detrimental feedback loop ensues as IR escalates, causing elevated insulin levels that exacerbate OS. Exploring the relations between OS and PCOS is crucial to fully understand the role of OS in the pathophysiology of PCOS and to develop effective treatment strategies to improve the quality of life of women affected by this condition. The role of antioxidants as potential therapies is also discussed.

Determination of molecular mechanisms of development and course of experimental diabetes mellitus in Wistar rats

The development and progression of diabetes involves several molecular mechanisms, in particular: insulin resistance, dysfunction of beta cells, inflammatory processes. These mechanisms can disrupt insulin signaling pathways, contribute to beta-cell apoptosis, and are not necessarily dependent on the intervention of cytokines and chemokines. Additionally, genetics play a role, as some forms of diabetes are caused by genetic mutations affecting insulin production or sensitivity. The molecular mechanisms underlying the development and progression of diabetes are complex and encompass various aspects of the body’s physiology and biochemistry. Understanding these mechanisms is crucial for the development of effective methods for treating and preventing diabetes. The aim of the work is analysis of the expression of genes, related to diabetes in pancreatic tissue samples of Wistar rats. Materials and methods. The polymerase chain reaction method with real-time reverse transcription was used to analyze gene expression using the RTI Profiler™ PCR Array Rat Diabetes kit (QIAGEN, Germany), where the pancreas was the object of research in experimental animals. Results. RTI Profiler™ PCR Array Rat Diabetes profiles the expression of 84 genes, associated with the onset, development, and progression of diabetes. The panel contains genes that contribute to obesity, insulin resistance, early-onset diabetes, and its late complications. These genes are represented by functional categories: receptors, transporters, and channels; nuclear receptors; metabolic enzymes; secretion factors; signal transduction proteins; transcription factors. According to the PCR results of the study of the control group of animals and animals with experimental diabetes, we established the activity of the Nkx2-1 genes; Pik3r1; Slc14a2 with high expression compared to control animals. Conclusions. The Nkx2-1 gene has been implicated in the pathogenesis of diabetes, as evidenced by its high expression activity compared to the control group of animals. Additionally, the Pik3r1 protein shows elevated expression levels in the group of animals with experimental diabetes. These changes are believed to be part of a compensatory mechanism aimed at preserving the cellular function of the pancreatic endocrine system. Furthermore, the observed increase in Slc14a2 protein expression likely indicates the onset of late complications associated with kidney pathology in the course of diabetes.

232-LB: Transcriptional Regulation of Adipocyte Insulin and Inflammatory Signaling by Early B-Cell Factor-1 (Ebf1)

Overnutrition is causally associated with many chronic diseases, including insulin resistance and diabetes, heart disease, hypertension, and cancer. Chronic activation of the innate immune system may lie at the heart of a majority of T2DM cases; the bulk of the evidence suggests that a litany of inflammatory cytokines and toxic lipid species released from irritated adipocytes contribute significantly to disrupted insulin signaling in metabolic tissues and may eventually lead to frank type 2 diabetes. However, the molecular mechanisms that initiate these inflammatory events in adipocytes remain unknown, particularly at the transcriptional level. Our previous work showed that the transcription factor Ebf1 regulates insulin signaling and promotes inflammation in adipocytes; however, the precise molecular mechanisms through which Ebf1 regulates the expression of inflammatory loci remain unknown (as evidence had suggested Ebf1 regulates these genes indirectly). We have recently discovered that Ebf1 can physically interact with multiple subunits of the well-known inflammatory transcription factor NF-κB, and many of the critical inflammatory loci showing impaired expression in Ebf1-deficient 3T3-L1 adipocytes also happen to be well-established NF-κB target genes. This striking result likely explains our paradoxical observations that EBF1 directly (and positively) regulates several core insulin signaling genes (Pik3r1, Akt, etc.) but also promotes insulin resistance in adipocytes—apparently without directly occupying inflammatory loci. We are currently working on physically and functionally characterizing these interactions and propose a model to explain the previously-mentioned paradox. If our hypothesis is correct, we anticipate that the eventual development of pharmaceutical agents designed to interfere with EBF1-NF-κB protein-protein interactions may represent a viable treatment for overnutrition-associated diabetes. Disclosure A. Gutierrez: None. Y. Martinez: None. K. Ibarra: None. Z. Bailey: None. M. Griffin: None. Funding National Institute of Diabetes and Digestive and Kidney Diseases

Brain insulin resistance and Alzheimer’s molecular changes induced by Western diet

AbstractBackgroundWestern diet (WD) is a type of nourishment based on ultra‐processed foods, rich in simple sugars and saturated fats. Long‐term consumption of WD may lead to disruption of insulin signaling and development of insulin resistance. It is supposed that insulin resistance is a probable risk factors for Alzheimer’s disease (AD). The aim of this study was to verify this hypothesis in wild type mice by checking the WD effect on initiation and propagation of main neuropathological AD features such as amyloid‐β (Aβ) plaques and neurofibrillary tangles, which start from the entorhinal cortex in the temporal area, and progresses to the hippocampus, resulting in the loss of memory and cognition.MethodMales of wild type C57BL/6J mice were fed WD diet or standard diet (SD; CTR). Mice experimental groups (WD and CTR) were divided into age subgroups 4‐, 8‐, 12‐ and 16‐month‐old. In the first step, the WD‐diet dependent insulin signaling was analyzed, and the levels of the insulin pathway components: p‐IRS‐1(Ser616), p‐Akt(473), p‐GSK‐3β(Ser9) in the entorhinal cortex and hippocampus were assessed. To analyze further whether WD‐derived impairments in insulin signaling may induce neuropathological AD features, p‐Tau(Thr231) and APP/Aβ were analyzed by immunoblotting and immunofluorescence of mouse brain tissue sections from entorhinal cortex and the hippocampus.ResultEntorhinal cortex proved to be more sensitive to WD‐dependent insulin impairments than the hippocampus: immunoblotting analysis of mouse entorhinal cortex brain lysates revealed an increase in p‐IRS‐1(Ser616) levels, indicating the development of insulin resistance under WD diet. Moreover, a change in the localization of p‐Tau(Thr231) in cellular compartments from fibers to nerve cell bodies indicated a progressive tauopathy. In addition, we also observed an age‐dependent decrease in APP protein levels correlating with the appearance of Aβ peptides in the cytoplasm of neurons under the WD diet.ConclusionObtained results suggest that the WD diet, by inducing abnormalities in insulin signaling in the brain, promotes the development of AD, and may be consider as a significant modifiable risk factor for AD, additional to the genetic risk factors.

Arsenic induces the global hypophosphorylation of insulin receptor substrate proteins in differentiated human neuroblastoma SH-SY5Y cells

We recently reported that arsenic disrupted neuronal insulin signaling. Here, we further investigated the effect of arsenic on insulin receptor substrate (IRS) proteins, which are crucial downstream signaling molecules of insulin in differentiated human neuroblastoma SH-SY5Y cells. We also found that prolonged arsenic treatment accelerated the migration of IRS1 and IRS2 on SDS-PAGE. Treatment with phosphatases abolished the arsenic-induced increased mobility of IRS, suggesting that the electrophoretic mobility shift of IRS on SDS-PAGE by arsenic was phosphorylation-dependent. By using label-free mass spectrometry, the phosphorylation sites of IRS1 were found to be S24, S345, S636, T774, S1057, S1058, and S1070, while those of IRS2 were at S645, Y653, T657, S665, S667, S669, S672, S915, and S1203, which were at least 2-fold lower than found in the control. These findings indicated a global hypophosphorylation of IRS proteins after prolonged arsenic treatment. In addition, four novel phosphorylation sites were identified on IRS1 (T774, S1057, S1058, and S1070), with another two on IRS2 (S665 and S667). As basal IRS phosphorylation plays an important role in insulin signaling, the reduction of IRS phosphorylation on multiple residues may underlie arsenic-impaired insulin signaling in neurons.

In Vitro Insulin Resistance Model: A Recent Update.

Insulin resistance, which affects insulin-sensitive tissues, including adipose tissues, skeletal muscle, and the liver, is the central pathophysiological mechanism underlying type 2 diabetes progression. Decreased glucose uptake in insulin-sensitive tissues disrupts insulin signaling pathways, particularly the PI3K/Akt pathway. An in vitro model is appropriate for studying the cellular and molecular mechanisms underlying insulin resistance because it is easy to maintain and the results can be easily reproduced. The application of cell-based models for exploring the pathogenesis of diabetes and insulin resistance as well as for developing drugs for these conditions is well known. However, a comprehensive review of in vitro insulin resistance models is lacking. Therefore, this review was conducted to provide a comprehensive overview and summary of the latest in vitro insulin resistance models, particularly 3T3-L1 (preadipocyte), C2C12 (skeletal muscle), and HepG2 (liver) cell lines induced with palmitic acid, high glucose, or chronic exposure to insulin.

Tris(4-chlorophenyl)methane and tris(4-chlorophenyl)methanol disrupt pancreatic organogenesis and gene expression in zebrafish embryos.

Tris(4-chlorophenyl) methane (TCPM) and tris(4-chlorophenyl)methanol (TCPMOH) are anthropogenic environmental contaminants believed to be manufacturing byproducts of the organochlorine pesticide dichlorodiphenyltrichloroethane (DDT) due to environmental co-occurrence. TCPM and TCPMOH are persistent, bioaccumulate in the environment, and are detected in human breast milk and adipose tissues. DDT exposures have been previously shown to disrupt insulin signaling and glucoregulation, increasing risk for diabetes. We have previously shown that embryonic exposures organochlorines such as polychlorinated biphenyls disrupted pancreatic development and early embryonic glucoregulatory networks. Here, we determined the impacts of the similar compounds TCPM and TCPMOH on zebrafish pancreatic growth and gene expression following developmental exposures. Zebrafish embryos were exposed to 50 nM TCPM or TCPMOH beginning at 24 hr postfertilization (hpf) and exposures were refreshed daily. At 96 hpf, pancreatic growth and islet area were directly visualized in Tg(ptf1a::GFP) and Tg(insulin::GFP) embryos, respectively, using microscopy. Gene expression was assessed at 100 hpf with RNA sequencing. Islet and total pancreas area were reduced by 20.8% and 13% in embryos exposed to 50 nM TCPMOH compared to controls. TCPM did not induce significant morphological changes to the developing pancreas, indicating TCPMOH, but not TCPM, impairs pancreatic development despite similarity in molecular responses. Transcriptomic responses to TCPM and TCPMOH were correlated (R2 =.903), and pathway analysis found downregulation of processes including retinol metabolism, circadian rhythm, and steroid biosynthesis. Overall, our data suggest that TCPM and TCPMOH may be hazardous to embryonic growth and development.