Improved Insulin Signaling Research Articles

The effect of heating therapy on the blood profile of white rats (Rattus norvegicus)

A decrease in the number of erythrocytes and hemoglobin levels was one of the complications of diabetes mellitus (DM). One of the treatments for DM patients used Heating Therapy (HT). Heating Therapy is a treatment in the form of heat exposure which can cause increased expression of heat shock protein (HSP), improve glucose metabolism, insulin sensitivity and improve insulin signaling. The aim of this research was to determine the effect of heating therapy on the blood profile of mice. This research used a Complete Random Plan, which had five treatments and six replications. Rats without treatment (K-), diabetic rats (K+), rats given HT at 37°C for 10 minutes (P1), HT at 37°C for 20 minutes (P2) and HT at 37°C for 30 minutes (P3)). Heating Therapy was given every day for 3 weeks. One-way ANOVA test was used to analyze research data. If there was a significant difference (P <0.05), then proceed with the Duncan post-hoc test. The results showed that the control group and the treated group of mice given HT had significant differences (P <0.05). By giving HT at a temperature of 37°C for 10 minutes was effective in increasing hemoglobin levels and improving the number of platelet cells in diabetic mice.

Insulin Sensitivity Controls Activity of Pathogenic CD4+ T Cells in Rheumatoid Arthritis.

Hyperinsulinemia connects obesity, and a poor lipid profile, with type 2 diabetes (T2D). Here, we investigated consequences of insulin exposure for T cell function in the canonical autoimmunity of rheumatoid arthritis (RA). We observed that insulin levels correlated with the glycolytic index of CD4+ cells but suppressed transcription of insulin receptor substrates, which was inversely related to insulin sensitivity. This connection between insulin levels and the glycolytic index was not seen in CD4+ cells of healthy controls. Exposure of CD4+ cells to insulin induced a senescent state recognized by cell cycle arrest and DNA content enrichment measured by flow cytometry. It also resulted in accumulation of DNA damage marker γH2AX. Insulin suppressed IFNγ production and induced the senescence-associated secretome in CD4+ cell cultures and in patients with hyperinsulinemia. Inhibition of JAK-STAT signaling (JAKi) improved insulin signaling, which activated the glycolytic index and facilitated senescence in CD4+ cell cultures. Treatment with JAKi was associated with an abundance of naïve and recent thymic emigrant T cells in the circulation of RA patients. Thus, we concluded that insulin exerts immunosuppressive ability by inducing senescence and inhibiting IFNγ production in CD4+ cells. JAKi promotes insulin effects and supports elimination of the pathogenic CD4+ cell in RA patients.

Donepezil improves skeletal muscle insulin resistance in obese mice via the AMPK/FGF21-mediated suppression of inflammation and ferroptosis.

Donepezil has traditionally been used in Alzheimer's disease treatment and is known for its ability to alleviate neural inflammation and apoptosis. However, its impact on insulin signaling remains unexplored. This study sought to elucidate the novel role of donepezil in mitigating skeletal muscle insulin resistance under hyperlipidemic conditions. Western blot analysis was used to assess the expression of various proteins of interest, whereas a glucose uptake assay was performed in skeletal muscle cells via commercially available kits. An in vitro model of obesity was developed using palmitate. These in vitro findings were corroborated in vivo via insulin resistance models established through high-fat diet (HFD) feeding in mice. Intraperitoneal glucose tolerance tests and insulin tolerance tests were performed on the experimental mice. The results revealed that donepezil treatment improved insulin signaling and inflammation in palmitate-treated C2C12 myocytes and the skeletal muscle of HFD-fed mice. Notably, donepezil treatment augmented FGF21 expression and AMPK phosphorylation in the myocytes and skeletal muscle of HFD-fed mice. Knockdown of FGF21 or AMPK via siRNA reversed the effects of donepezil on insulin signaling and inflammation in cultured myocytes. We also found that donepezil ameliorated skeletal muscle insulin resistance via the FGF21-mediated suppression of ferroptosis under hyperlipidemic conditions. These findings suggest that donepezil enhances the FGF21/AMPK axis, thereby mitigating inflammation and insulin resistance in skeletal muscle. This study introduces a novel therapeutic approach for treating Alzheimer's disease patients with insulin resistance.

HM-Chromanone Alleviates Hyperglycemia by Activating AMPK and PI3K/AKT Pathways in Mice Fed a High-Fat Diet.

We investigated potential antihyperglycemic effects of HM-chromanone (HMC), a homoisoflavonoid isolated from Portulaca oleracea, in mice fed a high-fat diet (HFD). Five-week-old male C57BL/6J mice (n = 24) were divided into three groups: controls, mice fed an HFD (11 weeks), and HFD-fed mice receiving HMC supplementation (8 weeks). Various analyses assessed liver and skeletal muscle proteins, pancreatic β-cell histology, blood glucose and HbA1c levels, and homeostatic index of insulin resistance (HOMA-IR). HMC supplementation significantly reduced fasting blood glucose and postprandial blood glucose levels in HFD-fed mice. HbA1c and serum insulin levels reduced significantly, and HOMA-IR improved. Compensatory β-cell hyperplasia was reduced, and pancreatic β-cell function improved. AMP-activated protein kinase (AMPK) was significantly activated in skeletal muscle and liver tissues. IRS-1tyr612 expression increased significantly. PI3K activation and Akt phosphorylation in skeletal muscles improved insulin signaling. Forkhead box protein O1 phosphorylation increased through hepatic AMPK activation. Phosphoenolpyruvate carboxykinase and glucose-6-phosphatase expression was inhibited. Glycogen synthase kinase 3β phosphorylation increased. HMC supplementation alleviated hyperglycemia by activating the AMPK and PI3K/Akt pathways in skeletal muscles and the AMPK pathway in the liver of HFD-fed mice.

Resistance Exercise Improves Glycolipid Metabolism and Mitochondrial Biogenesis in Skeletal Muscle of T2DM Mice via miR-30d-5p/SIRT1/PGC-1α Axis.

Exercise is a recognized non-pharmacological treatment for improving glucose homeostasis in type 2 diabetes (T2DM), with resistance exercise (RE) showing promising results. However, the mechanism of RE improving T2DM has not been clarified. This study aims to investigate the effects of RE on glucose and lipid metabolism, insulin signaling, and mitochondrial function in T2DM mice, with a focus on the regulatory role of miR-30d-5p. Our results confirmed that RE significantly improved fasting blood glucose, IPGTT, and ITT in T2DM mice. Enhanced expression of IRS-1, p-PI3K, and p-Akt indicated improved insulin signaling. RE improved glycolipid metabolism, as well as mitochondrial biogenesis and dynamics in skeletal muscle of T2DM mice. We also found that miR-30d-5p was upregulated in T2DM, and was downregulated after RE. Additionally, in vitro, over-expression of miR-30d-5p significantly increased lipid deposition, and reduced glucose uptake and mitochondrial biogenesis. These observations were reversed after transfection with the miR-30d-5p inhibitor. Mechanistically, miR-30d-5p regulates glycolipid metabolism in skeletal muscle by directly targeting SIRT1, which affects the expression of PGC-1α, thereby influencing mitochondrial function and glycolipid metabolism. Taken together, RE effectively improves glucose and lipid metabolism and mitochondrial function in T2DM mice, partly through regulating the miR-30d-5p/SIRT1/PGC-1α axis. miR-30d-5p could serve as a potential therapeutic target for T2DM management.

Mitochondria-Targeted DNA Repair Glycosylase hOGG1 Protects Against HFD-Induced Liver Oxidative Mitochondrial DNA Damage and Insulin Resistance in OGG1-Deficient Mice.

8-oxoguanine DNA glycosylase-1 (OGG1) is a DNA glycosylase mediating the first step in base excision repair which removes 7,8-dihydro-8-oxoguanine (8-oxoG) and repairs oxidized nuclear and mitochondrial DNA. Previous studies showed that OGG1 deficiency results in an increased susceptibility to high-fat diet (HFD)-induced obesity and metabolic dysfunction in mice, suggesting a crucial role of OGG1 in metabolism. However, the tissue-specific mechanisms of how OGG1 deficiency leads to insulin resistance is unknown. Thus, in the current study, we used a hyperinsulinemic-euglycemic clamp to evaluate in-depth glucose metabolism in male wild-type (WT) mice and Ogg1-/- (Ogg1-KO) mice fed an HFD. Ogg1-KO mice fed HFD were more obese, with significantly lower hepatic insulin action compared to WT/HFD mice. Targeting human OGG1 to mitochondria protected against HFD-induced obesity, insulin resistance, oxidative mitochondrial DNA damage in the liver and showed decreased expression of liver gluconeogenic genes in Ogg1-KO mice, suggesting a putative protective mechanism. Additionally, several subunits of oxidative phosphorylation protein levels were noticeably increased in Ogg1-KO/Tg compared to Ogg1-KO mice fed an HFD which was associated with improved insulin signaling. Our findings demonstrate the crucial role of mitochondrial hOGG1 in HFD-induced insulin resistance and propose several protective mechanisms which can further direct the development of therapeutic treatment.

Incretin-Based Therapies: A Promising Approach for Modulating Oxidative Stress and Insulin Resistance in Sarcopenia.

Recent studies have linked sarcopenia development to the hallmarks of diabetes, oxidative stress, and insulin resistance. The anti-oxidant and insulin sensitivityenhancing effects of incretin-based therapies may provide a promising option for the treatment of sarcopenia. This review aimed to unveil the role of oxidative stress and insulin resistance in the pathogenesis of sarcopenia and explore the potential benefits of incretin-based therapies in individuals with sarcopenia. PubMed, the Cochrane Library, and Google Scholar databases were searched by applying keywords relevant to the main topic, to identify articles that met our selection criteria. Incretin-based therapies manifested anti-oxidant effects by increasing the anti-oxidant defense system and decreasing free radical generation or by indirectly minimizing glucotoxicity, which was mainly achieved by improving insulin signaling and glucose homeostasis. Likewise, these drugs exhibit insulin-sensitizing activities by increasing insulin secretion, transduction, and β-cell function or by reducing inflammation and lipotoxicity. Incretin-based therapies, as modulators of oxidation and insulin resistance, may target the main pathophysiological factors of sarcopenia, thus providing a promising strategy for the treatment of this disease.

Impact of reduced hepatic ceramide levels in high-fat diet mice on glucose metabolism

Dysregulation of insulin action in hepatocytes, common in obesity, significantly contributes to insulin resistance, type 2 diabetes, and metabolic syndrome. Previous research highlights ceramides' role in these conditions. This study explores the impact of ceramides by silencing the serine palmitoyltransferase (Sptlc2) gene, crucial for the initial ceramide biosynthesis, using hydrodynamic gene delivery. Male C57BL/6 mice were randomly divided into three groups: one on a low-fat diet (LFD) receiving scrambled shRNA plasmids, another on a high-fat diet (HFD) with scrambled shRNA plasmids, and a third on HFD with a plasmid targeting Sptlc2. Analyses included RT-PCR for gene expression, western blot for protein levels, and UHPLC/MS/MS for lipid profiling. Glucose metabolism was evaluated via oral glucose tolerance tests, homeostatic model assessment of insulin resistance, and glucose-6-phosphate analysis. Results showed that HFD induces insulin resistance by inhibiting insulin signaling and increasing active lipid levels in hepatocytes. Sptlc2 silencing reduced ceramide accumulation, improving insulin signaling and glucose metabolism. Notably, ceramide synthesis inhibition did not significantly affect other lipid levels, highlighting ceramide's critical role in hepatic insulin resistance.

PSAT1 is upregulated by METTL3 to attenuate high glucose-induced retinal pigment epithelial cell apoptosis and oxidative stress

BackgroundDiabetic retinopathy (DR) is a major ocular complication of diabetes mellitus, and a significant cause of visual impairment and blindness in adults. Phosphoserine aminotransferase 1 (PSAT1) is an enzyme participating in serine synthesis, which might improve insulin signaling and insulin sensitivity. Furthermore, it has been reported that the m6A methylation in mRNA controls gene expression under many physiological and pathological conditions. Nevertheless, the influences of m6A methylation on PSAT1 expression and DR progression at the molecular level have not been reported.MethodsHigh-glucose (HG) was used to treat human retinal pigment epithelial cells (ARPE-19) to construct a cell injury model. PSAT1 and Methyltransferase-like 3 (METTL3) levels were detected by real-time quantitative polymerase chain reaction (RT-qPCR). PSAT1, B-cell lymphoma-2 (Bcl-2), Bcl-2 related X protein (Bax), and METTL3 protein levels were examined by western blot assay. Cell viability and apoptosis were detected by Cell Counting Kit-8 (CCK-8) and TUNEL assays. Reactive oxygen species (ROS), malondialdehyde (MDA), and Glutathione peroxidase (GSH-Px) levels were examined using special assay kits. Interaction between METTL3 and PSAT1 was verified using methylated RNA immunoprecipitation (MeRIP) and dual-luciferase reporter assay.ResultsPSAT1 and METTL3 levels were decreased in DR patients and HG-treated ARPE-19 cells. Upregulation of PSAT1 might attenuate HG-induced cell viability inhibition and apoptosis and oxidative stress promotion in ARPE-19 cells. Moreover, PSAT1 was identified as a downstream target of METTL3-mediated m6A modification. METTL3 might improve the stability of PSAT1 mRNA via m6A methylation.ConclusionMETTL3 might mitigate HG-induced ARPE-19 cell damage partly by regulating the stability of PSAT1 mRNA, providing a promising therapeutic target for DR.

Silencing the glycerol-3-phosphate acyltransferase-1 gene in the liver of mice fed a high-fat diet, enhances insulin sensitivity and glucose metabolism by promoting fatty acid beta-oxidation

BackgroundLiver plays a central role in systemic glucose and lipid metabolism. High-fat diet (HFD) and obesity are related to hepatic lipid accumulation and insulin resistance (InsR). Diacylglycerols (DAG) play a key role in the induction of InsR, however their involvement in hepatic InsR remains debated. This study aimed to clarify and confirm the role of glycero-3-phosphate acyltransferase 1 (GPAT1), a rate-limiting enzyme in DAG synthesis, in the progression of hepatic InsR in the context of HFD-induced lipid accumulation and insulin resistance in the liver. MethodsLiver-targeted GPAT1 silencing was performed using shRNA-mediated hydrodynamic gene delivery. Lipid species including LCA-CoA, sphingolipids, DAG and acyl-carnitines were quantified using UHPLC/MS/MS while insulin signalling was assessed at protein level by Western Blot. Hepatic glucose metabolism, including glucose-6-pasphate content and gluconeogenesis rate was evaluated using GC/MS. ResultsHFD-fed animals developed InsR, evidenced by increased HOMA-IR, enhanced gluconeogenesis and reduced glycogen content compared to controls. Hepatic GPAT1 silencing in HFD-fed animals resulted in a significant reduction of DAG and TAG levels, increased acyl-carnitines content and upregulated mitochondrial β-oxidation protein expression. These changes were accompanied by improved insulin signalling, enhanced glycogen storage, and reduced gluconeogenesis. ConclusionsSilencing GPAT1, and thereby reducing glycerolipid synthesis, promotes β-oxidation and ameliorates HFD-induced hepatic insulin resistance, confirming the enzyme's pivotal role in liver metabolic dysfunction associated with increased lipid supply.

7624 m6A mRNA Methylation in Brown Adipose Tissue Regulates Systemic Insulin Sensitivity via an Inter-Organ Prostaglandin Signaling Axis

Abstract Disclosure: L. Xiao: None. D. F De Jesus: None. C. Ju: None. J. Wei: None. J. Hu: None. A. DiStefano-Forti: None. T. Tsuji: None. C. Cero: None. V. Männistö: None. S.M. Manninen: None. S. Wei: None. O. Ijaduola: None. M. Blüher: Consulting Fee; Self; Amgen Inc, AstraZeneca, Bayer, Inc., Boehringer Ingelheim, Lilly USA, LLC, Novo Nordisk, Pfizer, Inc., Sanofi. A.M. Cypess: None. J. Pihlajamäki: None. Y. Tseng: None. C. He: Advisory Board Member; Self; Accent Therapeutics. R.N. Kulkarni: Advisory Board Member; Self; Novo Nordisk, Biomea, Inversago, REDD. Brown adipose tissue (BAT) has the capacity to regulate systemic metabolism through the secretion of “Batokines” including signaling lipids. N6-methyladenosine (m6A) is the most prevalent and abundant post-transcriptional mRNA modification and has been reported to regulate BAT adipogenesis and energy expenditure. Here, we demonstrate that the absence of the m6A writer, methyltransferase-like 14 (METTL14), modifies the BAT secretome to initiate inter-organ communication to improve systemic insulin sensitivity. Importantly, these phenotypes are independent of UCP1-mediated energy expenditure and thermogenesis. Using lipidomics, we identified prostaglandin E2 (PGE2) and prostaglandin F2a (PGF2a) as M14KO-BAT-secreted insulin sensitizers. Notably, circulatory PGE2 and PGF2a levels are inversely correlated with insulin sensitivity in humans. Furthermore, in vivo administration of PGE2 and PGF2a in high-fat diet-induced insulin-resistant obese mice recapitulates the phenotypes of Mettl14-deficient animals. PGE2 or PGF2a improves insulin signaling by suppressing the expression of specific AKT phosphatases. Mechanistically, METTL14-mediated m6A installation promotes decay of transcripts encoding prostaglandin synthases and their regulators in human and mouse brown adipocytes in a YTHDF2/3-dependent manner. Collectively, these findings reveal a novel biological mechanism in the m6A-dependent regulation of the BAT secretome in modulating systemic insulin sensitivity in both mice and humans. Presentation: 6/1/2024

Inhibiting TRIM8 alleviates adipocyte inflammation and insulin resistance by regulating the DUSP14/MAPKs pathway

ABSTRACT Obesity is a low-grade chronic inflammation induced by the pathological expansion of adipocytes which allows the development of obesity-associated metabolic diseases like type 2 diabetes mellitus (T2D) and non-alcoholic fatty liver disease (NAFLD). However, mechanisms regulating adipocyte inflammation remain poorly understood. Here, we observed that TRIM8 was upregulated in adipocyte inflammation and insulin resistance while DUSP14 was downregulated. TRIM8 deficiency and DUSP14 over-expression decreased the level of inflammatory cytokines, increased glucose uptake content, and improved insulin signalling transduction compared to LPS treatment alone. Conversely, silencing DUSP14 increased the expression of inflammatory cytokines. It decreased the glucose uptake content and the phosphorylation level of proteins involved in insulin signalling, further impairing insulin signalling and aggravating insulin resistance. Furthermore, The decreased level of inflammatory cytokines, increased glucose uptake, and improved insulin signalling transduction caused by TRIM8 deficiency were reversed by down-regulated DUSP14. Collectively, our findings revealed that TRIM8 can regulate adipocyte inflammation and insulin resistance by regulating the MAPKs pathway which is dependent on DUSP14.

LGR signaling mediates muscle-adipose tissue crosstalk and protects against diet-induced insulin resistance

Obesity impairs tissue insulin sensitivity and signaling, promoting type-2 diabetes. Although improving insulin signaling is key to reversing diabetes, the multi-organ mechanisms regulating this process are poorly defined. Here, we screen the secretome and receptome in Drosophila to identify the hormonal crosstalk affecting diet-induced insulin resistance and obesity. We discover a complex interplay between muscle, neuronal, and adipose tissues, mediated by Bone Morphogenetic Protein (BMP) signaling and the hormone Bursicon, that enhances insulin signaling and sugar tolerance. Muscle-derived BMP signaling, induced by sugar, governs neuronal Bursicon signaling. Bursicon, through its receptor Rickets, a Leucine-rich-repeat-containing G-protein coupled receptor (LGR), improves insulin secretion and insulin sensitivity in adipose tissue, mitigating hyperglycemia. In mouse adipocytes, loss of the Rickets ortholog LGR4 blunts insulin responses, showing an essential role of LGR4 in adipocyte insulin sensitivity. Our findings reveal a muscle-neuronal-fat-tissue axis driving metabolic adaptation to high-sugar conditions, identifying LGR4 as a critical mediator in this regulatory network.

N-3 and n-6 Polyunsaturated Fatty Acids Modulate Macrophage-Myocyte Inflammatory Crosstalk and Improve Myocyte Insulin Sensitivity.

In obesity, circulating saturated fatty acids (SFAs) and inflammatory cytokines interfere with skeletal muscle insulin signaling, leading to whole body insulin resistance. Further, obese skeletal muscle is characterized by macrophage infiltration and polarization to the inflammatory M1 phenotype, which is central to the development of local inflammation and insulin resistance. While skeletal muscle-infiltrated macrophage-myocyte crosstalk is exacerbated by SFA, the effects of other fatty acids, such as n-3 and n-6 polyunsaturated fatty acids (PUFAs), are less studied. Thus, the objective of this study was to determine the effects of long-chain n-3 and n-6 PUFAs on macrophage M1 polarization and subsequent effects on myocyte inflammation and metabolic function compared to SFA. Using an in vitro model recapitulating obese skeletal muscle cells, differentiated L6 myocytes were cultured for 24 h with RAW 264.7 macrophage-conditioned media (MCM), followed by insulin stimulation (100 nM, 20 min). MCM was generated by pre-treating macrophages for 24 h with 100 μM palmitic acid (16:0, PA-control), arachidonic acid (20:4n-6, AA), or docosahexaenoic acid (22:6n-3, DHA). Next, macrophage cultures were stimulated with a physiological dose (10 ng/mL) of lipopolysaccharide for an additional 12 h to mimic in vivo obese endotoxin levels. Compared to PA, both AA and DHA reduced mRNA expression and/or secreted protein levels of markers for M1 (TNFα, IL-6, iNOS; p < 0.05) and increased those for M2 (IL-10, TGF-β; p < 0.05) macrophage polarization. In turn, AA- and DHA-derived MCM reduced L6 myocyte-secreted cytokines (TNFα, IL-6; p < 0.05) and chemokines (MCP-1, MIP-1β; p < 0.05). Only AA-derived MCM increased L6-myocyte phosphorylation of Akt (p < 0.05), yet this was inconsistent with improved insulin signaling, as only DHA-derived MCM improved L6 myocyte glucose uptake (p < 0.05). In conclusion, dietary n-3 and n-6 PUFAs may be a useful strategy to modulate macrophage-myocyte inflammatory crosstalk and improve myocyte insulin sensitivity in obesity.

Ovalbumin Hydrolysates Enhance Skeletal Muscle Insulin-Dependent Signaling Pathway in High-Fat Diet-Fed Mice.

Egg white hydrolysates (EWH) and ovotransferrin-derived peptides have distinct beneficial effects on glucose metabolism. This research aims to investigate whether ovalbumin hydrolysates (OVAHs), without ovotransferrin can improve insulin signaling pathway in high-fat diet (HFD)-fed mice. Two types of ovalbumin hydrolysates were produced, either using thermoase (OVAT), or thermoase + pepsin (OVATP). Both OVAHs-supplemented groups exhibited lower body weight gain (P < 0.001) and enhanced oral glucose tolerance (P < 0.05) compared with HFD. Moreover, diet supplementation with either hydrolysate increased the insulin-stimulated activation of protein kinase B (AKT) and insulin receptor β (IRβ) (P < 0.0001) in skeletal muscle. In conclusion, OVAHs improved glucose tolerance and insulin-dependent signaling pathway in HFD-fed mice.

Brain responses to intermittent fasting and the healthy living diet in older adults

Diet may promote brain health in metabolically impaired older individuals. In an 8-week randomized clinical trial involving 40 cognitively intact older adults with insulin resistance, we examined the effects of 5:2 intermittent fasting and the healthy living diet on brain health. Although intermittent fasting induced greater weight loss, the two diets had comparable effects in improving insulin signaling biomarkers in neuron-derived extracellular vesicles, decreasing the brain-age-gap estimate (reflecting the pace of biological aging of the brain) on magnetic resonance imaging, reducing brain glucose on magnetic resonance spectroscopy, and improving blood biomarkers of carbohydrate and lipid metabolism, with minimal changes in cerebrospinal fluid biomarkers for Alzheimer's disease. Intermittent fasting and healthy living improved executive function and memory, with intermittent fasting benefiting more certain cognitive measures. In exploratory analyses, sex, body mass index, and apolipoprotein E and SLC16A7 genotypes modulated diet effects. The study provides a blueprint for assessing brain effects of dietary interventions and motivates further research on intermittent fasting and continuous diets for brain health optimization. For further information, please see ClinicalTrials.gov registration: NCT02460783.

Marine-Derived Phosphoeleganin and Its Semisynthetic Derivative Decrease IL6 Levels and Improve Insulin Signaling in Human Hepatocellular Carcinoma Cells.

Marine natural products constitute a great source of potential new antidiabetic drugs. The aim of this study was to evaluate the role of phosphoeleganin (PE), a polyketide purified from the Mediterranean ascidian Sidnyum elegans, and its derivatives PE/2 and PE/3 on insulin sensitivity in human hepatocellular carcinoma (HepG2) cells. In our experiments, insulin stimulates the phosphorylation of its receptor (INSR) and AKT by 1.5- and 3.5-fold, respectively, whereas in the presence of PE, PE/2, and PE/3, the insulin induced INSR phosphorylation is increased by 2.1-, 2-, and 1.5-fold and AKT phosphorylation by 7.1-, 6.0-, and 5.1-fold, respectively. Interestingly, PE and PE/2 have an additive effect on insulin-mediated reduction of phosphoenolpyruvate carboxykinase (PEPCK) expression. Finally, PE and PE/2, but not PE/3, decrease interleukin 6 (IL6) secretion and expression before and after palmitic acid incubation, while in the presence of high glucose (HG), only PE reduces IL6. Levels of other cytokines are not significantly affected by PE and its derivates. All these data suggest that PE and its synthetic-derived compound, PE/2, significantly decrease IL6 and improve hepatic insulin signaling. As IL6 impairs insulin action, it could be hypothesized that PE and PE/2, by inhibiting IL6, may improve the hepatic insulin pathway.

Phosphoenolpyruvate carboxykinase-1 targeted siRNA promotes wound healing in type 2 diabetic mice by restoring glucose homeostasis

It is well-accepted that the liver plays a vital role in the metabolism of glucose and its homeostasis. Dysregulated hepatic glucose production and utilization, leads to type 2 diabetes (T2DM). In the current study, RNA sequencing and qRT-PCR analysis of nanoformulation-treated T2DM mice (TGthr group) revealed beneficial crosstalk of PCK-1 silencing with other pathways involved in T2DM. The comparison of precise genetic expression profiles of the different experimental groups showed significantly improved hepatic glucose, fatty acid metabolism and several other T2DM-associated crucial markers after the nanoformulation treatment. As a result of these improvements, we observed a significant acceleration in wound healing and improved insulin signaling in vascular endothelial cells in the TGthr group as compared to the T2DM group. Enhanced phosphorylation of PI3K/Akt pathway proteins in the TGthr group resulted in increased angiogenesis as observed by the increased expression of endothelial cell markers (CD31, CD34) thereby improving endothelial dysfunctions in the TGthr group. Additionally, therapeutic nanoformulation has been observed to improve the inflammatory cytokine profile in the TGthr group. Overall, our results demonstrated that the synthesized therapeutic nanoformulation referred to as GPR8:PCK-1siRNA holds the potential in ameliorating hyperglycemia-associated complications such as delayed wound healing in diabetes.

Effect of resveratrol on insulin action in primary myotubes from lean individuals and individuals with severe obesity.

Resveratrol, a natural polyphenol compound contained in numerous plants, has been proposed as a treatment for obesity-related disease processes such as insulin resistance. However, in humans there are conflicting results concerning the efficacy of resveratrol in improving insulin action; the purpose of the present study was to determine whether obesity status (lean, severely obese) affects the response to resveratrol in human skeletal muscle. Primary skeletal muscle cells were derived from biopsies obtained from age-matched lean and insulin-resistant women with severe obesity and incubated with resveratrol (1 µM) for 24 h. Insulin-stimulated glucose oxidation and incorporation into glycogen, insulin signal transduction, and energy-sensitive protein targets [AMP-activated protein kinase (AMPK), Sirt1, and PGC1α] were analyzed. Insulin-stimulated glycogen synthesis, glucose oxidation, and AMPK phosphorylation increased with resveratrol incubation compared with the nonresveratrol conditions (main treatment effect for resveratrol). Resveratrol further increased IRS1, Akt, and TBC1D4 insulin-stimulated phosphorylation and SIRT1 content in myotubes from lean women, but not in women with severe obesity. Resveratrol improves insulin action in primary human skeletal myotubes derived from lean women and women with severe obesity. In women with obesity, these improvements may be associated with enhanced AMPK phosphorylation with resveratrol treatment.NEW & NOTEWORTHY A physiologically relevant dose of resveratrol increases insulin-stimulated glucose oxidation and glycogen synthesis in myotubes from individuals with severe obesity. Furthermore, resveratrol improved insulin signal transduction in myotubes from lean individuals but not from individuals with obesity. Activation of AMPK plays a role in resveratrol-induced improvements in glucose metabolism in individuals with severe obesity.

Daily Consumption of Golden Berry (Physalis peruviana) Has Been Shown to Halt the Progression of Insulin Resistance and Obesity in Obese Rats with Metabolic Syndrome.

In a study addressing the high risk of chronic diseases in people with diabetes and obesity linked to metabolic syndrome, the impact of a Golden Berry diet was investigated using a diabetic animal model. Obese rats with diabetic characteristics were fed a diet containing five percent Golden Berry for 16 days. This study focused on various parameters including organ weights, expression of metabolic genes, and urinary biomarkers. Post-Golden Berry intake, there was a notable decrease in the body, liver, pancreas, visceral, and subcutaneous adipose tissue weights in these obese, hyperglycemic rats. In contrast, an increase in brown adipose tissue (BAT) cell mass was observed. This diet also resulted in reduced blood glucose levels and normalized plasma biochemical profiles, including cholesterol, triglycerides, LDL, and HDL levels. Additionally, it modulated specific urinary biomarkers, particularly pipe-colic acid, a primary marker for type 2 diabetes. Bioinformatics analysis linked these dietary effects to improved insulin signaling and adipogenesis. Regular consumption of Golden Berry effectively prevented insulin resistance and obesity in rats, underscoring its significant health benefits and the protective role of an antioxidant-rich diet against metabolic syndrome. These findings offer promising insights for future therapeutic strategies to manage and prevent obesity and related chronic diseases.