The PI3K/AKT pathway in obesity and type 2 diabetes

Calpain inhibitor and ibudilast rescue β cell functions in a cellular model of Wolfram syndrome

Wolfram syndrome is a rare multisystem disease characterized by childhood-onset diabetes mellitus and progressive neurodegeneration. Most cases are attributed to pathogenic variants in a single gene, Wolfram syndrome 1 (WFS1). There currently is no disease-modifying treatment for Wolfram syndrome, as the molecular consequences of the loss of WFS1 remain elusive. Because diabetes mellitus is the first diagnosed symptom of Wolfram syndrome, we aimed to further examine the functions of WFS1 in pancreatic β cells in the context of hyperglycemia. Knockout (KO) of WFS1 in rat insulinoma (INS1) cells impaired calcium homeostasis and protein kinase B/Akt signaling and, subsequently, decreased cell viability and glucose-stimulated insulin secretion. Targeting calcium homeostasis with reexpression of WFS1, overexpression of WFS1's interacting partner neuronal calcium sensor-1 (NCS1), or treatment with calpain inhibitor and ibudilast reversed deficits observed in WFS1-KO cells. Collectively, our findings provide insight into the disease mechanism of Wolfram syndrome and highlight new targets and drug candidates to facilitate the development of a treatment for this disorder and similar diseases.

Cyanidin-3-O-glucoside restores insulin signaling and reduces inflammation in hypertrophic adipocytes

Obesity is a metabolic disorder characterized by excess adipose tissue, macrophages infiltration, and inflammation which in turn lead to insulin-resistance. Epidemiological evidences reported that anthocyanins possess not only high antioxidant and antiinflammatory activities, but also improve metabolic complications associated with obesity. The aim of this work was to evaluate the in vitro beneficial effects of cyanidin-3-O-glucoside (C3G) in counteracting inflammation and insulin-resistance in 3T3-L1 hypertrophic adipocytes exposed to palmitic acid (PA). In the present study murine 3T3-L1 adipocytes were pretreated with C3G for 24 h and then exposed to palmitic acid (PA) for 24 h. Real-time PCR, western blotting analysis and Oil Red O staining were applied for investigating the mechanism involved in adipocytes dysfunction. C3G pretreatment reduced lipid accumulation, PPARγ pathway and NF-κB pathway induced by PA in murine adipocytes. In addition, our data demonstrated that PA reduced insulin signaling via IRS-1 Ser³⁰⁷phosphorylation while C3G dose-dependently improved insulin sensitivity restoring IRS-1/PI3K/Akt pathway. Furthermore, C3G improved adiponectin mRNA levels altered by PA in 3T3-L1 murine and SGBS human adipocytes. Herein reported data demonstrate that C3G ameliorated adipose tissue dysfunction, thus suggesting new potential roles for this compound of nutritional interest in the prevention of pathological conditions linked to obesity.

Wolfram Syndrome: a Monogenic Model to Study Diabetes Mellitus and Neurodegeneration

Wolfram syndrome (WS) is a rare, progressive disorder characterized by childhood-onset diabetes mellitus, optic nerve atrophy, hearing loss, diabetes insipidus, and neurodegeneration. Currently, there is no effective treatment for WS, and patients typically die between 30 and 40 years of age. WS is primarily caused by autosomal recessive mutations in the Wolfram syndrome 1 (WFS1) gene (OMIM 222300), which encodes for wolframin (WFS1). This disorder is therefore a valuable monogenic model for prevalent diseases, particularly diabetes mellitus and neurodegeneration. Whereas reduced survival and secretion are known cellular impairments causing WS, the underlying molecular pathways and the physiological function of WFS1 remain incompletely described. Here, we characterize WFS1 as a regulator of intracellular calcium homeostasis, review our current understanding of the disease mechanism of WS, and discuss candidate treatment approaches. These insights will facilitate identification of new therapeutic strategies not only for WS but also for diabetes mellitus and neurodegeneration.

Diabetes and metabolic syndrome as risk factors for COVID-19

BACKGROUND AND AIMS

Clinical evidence exists that patients with diabetes are at higher risk for Coronavirus disease 2019 (COVID-19). We investigated the physiological origins of this clinical observation linking diabetes with severity and adverse outcome of COVID-19.

METHODS

Publication mining was applied to reveal common physiological contexts in which diabetes and COVID-19 have been investigated simultaneously. Overall, we have acquired 1,121,078 publications from PubMed in the time span between 01-01-2000 and 17-04-2020, and extracted knowledge graphs interconnecting the topics related to diabetes and COVID-19.

RESULTS

The Data Mining revealed three pathophysiological pathways linking diabetes and COVID-19. The first pathway indicates a higher risk for COVID-19 because of a dysregulation of Angiotensin-converting enzyme 2. The other two important physiological links between diabetes and COVID-19 are liver dysfunction and chronic systemic inflammation. A deep network analysis has suggested clinical biomarkers predicting the higher risk: Hypertension, elevated serum Alanine aminotransferase, high Interleukin-6, and low Lymphocytes count.

CONCLUSIONS

The revealed biomarkers can be applied directly in clinical practice. For newly infected patients, the medical history needs to be checked for evidence of a long-term, chronic dysregulation of these biomarkers. In particular, patients with diabetes, but also those with prediabetic state, deserve special attention.

Spiraeoside protects human cardiomyocytes against high glucose-induced injury, oxidative stress, and apoptosis by activation of PI3K/Akt/Nrf2 pathway

The present study aimed to explore the effect of spiraeoside, an active quercetin glucoside, on diabetic cardiomyopathy in vitro. Our results showed that spiraeoside attenuated high glucose (HG)-induced reduction of cell viability and increased myocardial enzymes lactate dehydrogenase and aspartate aminotransferase in AC16 cells. Spiraeoside exerted antioxidant activity in HG-induced AC16 cells as spiraeoside inhibited reactive oxygen species and malondialdehyde production and increased activities of superoxide dismutase, glutathione peroxidase, and catalase. Spiraeoside prevented HG-induced apoptosis of AC16 cells. HG stimulation-caused the decrease in the expression levels of p-Akt, nuclear Nrf2, and HO-1 was elevated after spiraeoside treatment in AC16 cells. However, the effects of spiraeoside were reversed by LY294002. In conclusion, spiraeoside protected AC16 cells against HG-induced oxidative stress, cell injury, and apoptosis. The protective effect of spiraeoside was regulated by the PI3K/Akt/Nrf2 signaling pathway.

Association of microRNA gene polymorphisms with Type 2 diabetes mellitus: A systematic review and meta-analysis

Background:

Type 2 diabetes mellitus (T2DM) is a metabolic disorder with growing prevalence and increasing economic burden. Based on the role of genetics and epigenetic factors on T2DM, we aimed to carry a systematic review and meta-analysis for all miRNA gene polymorphisms and risk of T2DM.

Materials and Methods:

A computerized literature search was carried out on PubMed, Web of Science, Scopus, Embase, as well as references of relevant review/meta-analysis. Key search terms were “Diabetes Mellitus, Type 2,” “MicroRNAs,” and “Polymorphism, Single Nucleotide.” All types of observational studies from January 1, 1992, to November 30, 2019, were included, without language restriction. Data analysis was performed using R programming language (3.5.2). Level of heterogeneity was obtained by Cochran's Q test (P < 0.05), and subgroup analysis was performed based on ethnicity.

Results:

Thirty-two polymorphisms from fifteen articles were included. Meta-analysis was carried out based on minor allele frequencies. Seven studies with 2193 cases and 3963 controls were included for rs2910164 polymorphism. In subgroup analysis, there were significant results in Caucasian population in dominant model (odds ratio [OR] =1.12; 95% confidence interval [CI]: 0.83–1.51), homozygote model (OR = 1.78; 95% CI: 1.06–3.00), heterozygote model (OR = 1.77; 95% CI: 1.03–3.05), and recessive model (OR = 1.78; 95% CI: 1.07–2.96). Four studies with 2085 cases and 1933 controls were included for rs895819 polymorphism. Overall, there was no significant result for association with rs895819, but subgroup analysis revealed that minor allele significantly decreased the risk of T2DM in Caucasians by recessive model (OR = 0.34; 95% CI: 0.18–0.66), dominant model (OR = 0.70; 95% CI: 0.52–0.94), homozygote model (OR = 0.32; 95% CI: 0.16–0.62), heterozygote model (OR = 0.37; 95% CI: 0.19–0.74), allelic model (OR = 0.67; 95% CI: 0.52–0.85).

Conclusion:

The minor allele of rs2910164 may increase the risk of T2DM by leading to lower level of miR-146a. In contrast, minor allele of rs895819 may decrease the risk of T2DM by leading to higher level of miR-27a.

Differential proteomics analysis of serum exosomein burn patients

The exosome is an emerging concepts biomarkers due to their abnormal expression in various diseases. Research on exosome has already shifted from the laboratory to clinical application. This study uses bioinformatics technology to identify functional changes in proteins of serum exosomes from burn patients. A total of 231 quantifiable differentially-expressed proteins were screened out, 31 of them had statistically significant changes in expression levels. In the test group, expression of2 proteins had downregulated, whereas that of 29 proteins upregulated. Gene Ontology analysis demonstrates that differentially-expressed proteins were primarily identified in extracellular vesicles and platelet α granules, which can alter enzyme inhibitor activities, heparin-binding, coagulation, and lipid transport. Kyoto Encyclopedia of Genes and Genomes pathway analysis demonstrates that ITGA2B and ITGB3 proteins, which were significantly upregulated in the burn group, were primarily involved in the PI3K/AKT signaling pathway. Western blotting confirmed that the expressions of ITGA2B and ITGB3 in burn patient tissue samples were higher than those in the control group; conversely, the expression of CD9 was lower than that in the control group. In burn patients, the upregulated proteins ITGA2B and ITGB3 of serum exosomes likely participate in injury detection and repair via PI3K/AKT signaling pathways.

Nanocurcumin alleviates insulin resistance and pancreatic deficits in polycystic ovary syndrome rats: Insights on PI3K/AkT/mTOR and TNF-α modulations

INTRODUCTION AND AIMS

Polycystic ovary syndrome (PCOS) is a widespread endocrine disorder affecting females. Mechanisms underlying PCOS complicated pathology remain largely unknown, making current treatment only symptomatic. Increasing reports suggest impaired PI3K/AKT/mTOR pathway and tumor necrosis factor-α (TNF-α) levels are involved in cellular proliferation and metabolism-related disorders. However, rare data explored their role in PCOS. Hence, this study investigated TNF-α and pancreatic PI3K/AKT/mTOR levels in PCOS animal model and evaluated their effects on developed pancreatic deficits. Secondly; we explored the impact of nanocurcumin as powerful anti-inflammatory supplement against these developed pancreatic pathologies.

METHODS

PCOS was induced in rats using letrozole. Nanocurcumin was formulated to increase solubility and bioavailability of curcumin. Transmission electron microscopy (TEM), zeta potential and Infra-red spectroscopy (FT-IR) were used for characterization. Nanocurcumin was orally ingested for 15 days.

FINDINGS

PCOS group exhibited significant disturbance in sex hormones, oxidative stress markers, and TNF-α levels as determined by immunoassay. Western blotting revealed significant reduction of PI3K/AKT/mTOR levels leading to impaired insulin sensitivity, decreased β cells function and mass as confirmed by HOMA assessments and immunohistochemistry. Nanocurcumin significantly improved oxidative markers, glucose indices and TNF-α levels. It reinstated PI3K/AKT/mTOR levels, alleviated insulin resistance, and retained islets integrity consequently restoring normal sex hormonal levels.

SIGNIFICANCE

To the best of our knowledge, the study is the first to report pancreatic role of PI3K/AKT/mTOR and TNF-α in PCOS and the first to demonstrate nanocurcumin promising potential against PCOS-related pancreatic molecular and histological pathologies that can indeed offer better control of the disease.

ZNF322A-mediated protein phosphorylation induces autophagosome formation through modulation of IRS1-AKT glucose uptake and HSP-elicited UPR in lung cancer

Background

ZNF322A is an oncogenic transcription factor that belongs to the Cys2His2-type zinc-finger protein family. Accumulating evidence suggests that ZNF322A may contribute to the tumorigenesis of lung cancer, however, the ZNF322A-mediated downstream signaling pathways remain unknown.

Methods

To uncover ZNF322A-mediated functional network, we applied phosphopeptide enrichment and isobaric labeling strategies with mass spectrometry-based proteomics using A549 lung cancer cells, and analyzed the differentially expressed proteins of phosphoproteomic and proteomic profiles to determine ZNF322A-modulated pathways.

Results

ZNF322A highlighted a previously unidentified insulin signaling, heat stress, and signal attenuation at the post-translational level. Consistently, protein-phosphoprotein-kinase interaction network analysis revealed phosphorylation of IRS1 and HSP27 were altered upon ZNF322A-silenced lung cancer cells. Thus, we further investigated the molecular regulation of ZNF322A, and found the inhibitory transcriptional regulation of ZNF322A on PIM3, which was able to phosphorylate IRS1 at serine¹¹⁰¹ in order to manipulate glucose uptake via the PI3K/AKT/mTOR signaling pathway. Moreover, ZNF322A also affects the unfolded protein response by phosphorylation of HSP27^S82 and eIF2a^S51, and triggers autophagosome formation in lung cancer cells.

Conclusions

These findings not only give new information about the molecular regulation of the cellular proteins through ZNF322A at the post-translational level, but also provides a resource for the study of lung cancer therapy.

Semaphorin 3 C is a Novel Adipokine Representing Exercise-Induced Improvements of Metabolism in Metabolically Healthy Obese Young Males

This study investigated the endurance exercise-induced changes in lesser known adipokines (visfatin, chemerin, apelin, semaphorin 3 C) related to obesity and metabolism, and their correlations with the changes in the parameters of obesity and glucose homeostasis. Forty metabolically healthy obese young males were randomly assigned to control group (C, n = 12) or exercise group (Ex, n = 28). The subjects in Ex participated in a 8-week supervised endurance exercise training program, comprised of four sessions of treadmill running at 65–70% of VO_2max per week. Serum levels of visfatin, chemerin, apelin, and semaphorin 3 C were significantly decreased in Ex. At baseline, apelin and semaphorin 3 C appeared to be correlated with obesity measures, including body mass index, % total fat and trunk fat, and waist circumference. Exercise-induced changes in these obesity measures significantly correlated with the changes in chemerin and semaphorin 3 C. Basal chemerin, apelin and semaphorin 3 C correlated with glucose homeostasis parameters, including fasting plasma glucose, fasting plasma insulin, homeostasis model assessment of insulin resistance and β-cell function, and quantitative insulin-sensitivity check index to different extents. Furthermore, the changes in apelin and semaphorin 3 C well predicted the improvements in glycemic parameters. We suggest that semaphorin 3 C is a novel adipokine involved in pathophysiology of obesity and metabolism, and that it is a biomarker representing an exercise-induced improvement in metabolically healthy obese young males.

Comparative profiles of DNA methylation and differential gene expression in osteocytic areas from aged and young mice

Altered DNA methylation upon ageing may result in many age-related diseases such as osteoporosis. However, the changes in DNA methylation that occur in cortical bones, the major osteocytic areas, remain unknown. In our study, we extracted total DNA and RNA from the cortical bones of 6-month-old and 24-month-old mice and systematically analysed the differentially methylated regions (DMRs), differentially methylated promoters (DMPs) and differentially expressed genes (DEGs) between the mouse groups. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of the DMR-related genes revealed that they were mainly associated with metabolic signalling pathways, including glycolysis, fatty acid and amino acid metabolism. Other genes with DMRs were related to signalling pathways that regulate the growth and development of cells, including the PI3K-AKT, Ras and Rap1 signalling pathways. The gene expression profiles indicated that the DEGs were mainly involved in metabolic pathways and the PI3K-AKT signalling pathway, and the profiles were verified through real-time quantitative PCR (RT-qPCR). Due to the pivotal roles of the affected genes in maintaining bone homeostasis, we suspect that these changes may be key factors in age-related bone loss, either together or individually. Our study may provide a novel perspective for understanding the osteocyte and its relationship with osteoporosis during ageing. SIGNIFICANCE OF THE STUDY: Our study identified age-related changes in gene expressions in osteocytic areas through whole-genome bisulfite sequencing (WGBS) and RNA-seq, providing new theoretical foundations for the targeted treatment of senile osteoporosis.

Gene ontology enrichment analysis of α-amylase inhibitors from Duranta repens in diabetes mellitus

Background

Although α-amylase is the choice of target to manage postprandial hyperglycemia, inhibitors of this enzyme may get absorbed into the systemic circulation and modulate proteins involved in the pathogenesis of diabetes mellitus. Hence, the present study aimed to identify α-amylase inhibitors from Duranta repens via in silico and in vitro and predict their role in the modulation of multiple pathways involved in diabetes mellitus.

Methods

α-amylase inhibitory activity of hydroalcoholic extract/fractions (s) and pure compounds from D. repens was performed using in vitro enzyme inhibitory assay. Multiple open-source databases and published literature were used to retrieve reported phytoconstituents present in D. repens and their targets. The network was constructed between α-amylase inhibitors, modulated proteins, and expressed pathways. Further, hit molecules were also confirmed for their potency to inhibit α-amylase using in silico molecular docking and in vitro enzyme inhibitory assay. The glucose uptake assay was performed to assess the effect of hydrolcoholic extract/fraction(s) using rat hemidiaphragm.

Results

Fraction rich in flavonoids showed the highest α-amylase inhibitory activity with a IC₅₀ of 644.29 ± 4.36 µg/ml compared to other fractions. PI3K-Akt signaling pathway and p53 signaling pathway were predicted to be primarily modulated in the compound-protein-pathway network. Similarly, scutellarein was predicted as lead hit based on α-amylase inhibitory action, binding affinity, and regulated pathways. Further, α-amylase inhibitors were also predicted to modulate the pathways involved in diabetes complications like AGE-RAGE and FoxO signaling pathway. Fraction rich in flavonoids showed the highest glucose uptake in rat hemidiaphragm with an effective concentration of 534.73 ± 0.79 µg/ml.

Conclusions

The α-amylase inhibitors from D. repens may not be limited within the gastrointestinal tract to inhibit α-amylase but may get absorbed into the systemic circulation and modulate multiple pathways involved in the pathogenesis of diabetes mellitus to produce synergistic/additive effect.

Altered expression of AKT1 and P38A in the colons of patients with Hirschsprung's disease

PURPOSE

Hirschsprung's disease (HSCR) is a functional obstruction of the gastrointestinal tract due to the congenital absence of enteric ganglion cells. The proto-oncogene RET is one of the primary genes implicated in the aetiology of HSCR. We designed this study to investigate the expression of 10 RET regulatory network genes in the colons of patients with HSCR.

METHODS

HSCR tissue specimens (n = 28) were collected at the time of pull-through surgery. qPCR analysis was applied to compare the expression levels of 10 genes in the RET regulatory network. Western blot analysis was performed to quantify the protein expression. Immunohistochemistry was performed to determine the localization of AKT1 and P38A in HSCR colon tissue.

RESULTS

AKT1 (p = 0.015) and P38A (p = 0.039) were both significantly downregulated in the aganglionic segment compared to those in the ganglionic segment in HSCR patients (n = 28). Western blot analysis revealed the decreasing protein expression of AKT1 and P38A in the aganglionic segment compared to ganglionic segment and control colon tissues (p < 0.05). Immunohistochemistry staining revealed that both AKT1 and P38A were localized in the colonic mucosa and were significantly decreased in the aganglionic segment.

CONCLUSION

To our knowledge, we report for the first time the expression of RET regulatory network genes in the colons of patients with HSCR. The markedly decreased expression of AKT1 and P38A suggested a possible role in HSCR pathogenesis.

C1q/TNF-related Protein 1, a Multifunctional Adipokine: An Overview of Current Data

The present review aimed to present the research highlights on C1q/TNF-related protein 1 (CTRP1), a member of the recently discovered family of highly conserved adiponectin paralog proteins, C1q tumor necrosis factor-related proteins. CTRP1 plays an important role in regulating body energy homeostasis and sensitivity to insulin. Studies on animal models have shown that it lowers the concentration of glucose. Elevated concentrations of CTRP1 reduce weight gain and diet-induced insulin resistance. CTRP1 limits the extent of ischemia-reperfusion injury in acute myocardial infarction. It inhibits platelet aggregation by blocking von Willebrand factor binding to collagen. In patients with chronic kidney disease, an increase in CTRP1 levels is associated with a lesser degree of disease progression. CTRP1 stimulates aldosterone synthesis in the adrenal cortex by affecting aldosterone synthase expression. In dehydration, an increase in CTRP1 concentration helps to maintain normotension. It participates in processes related to the proliferation and maturation of chondrocytes. It also promotes atherosclerosis, and a surge in its concentration is correlated with a higher cardiovascular risk in patients with coronary atherosclerosis. In vascular smooth muscle cells, it induces the expression of proinflammatory cytokines. An increase in CTRP1 levels is correlated with the progression of the neoplastic process in patients with glioblastoma.

Pathogenic Pathways and Therapeutic Approaches Targeting Inflammation in Diabetic Nephropathy

Diabetic nephropathy (DN) is associated with an increased morbidity and mortality, resulting in elevated cost for public health systems. DN is the main cause of chronic kidney disease (CKD) and its incidence increases the number of patients that develop the end-stage renal disease (ESRD). There are growing epidemiological and preclinical evidence about the close relationship between inflammatory response and the occurrence and progression of DN. Several anti-inflammatory strategies targeting specific inflammatory mediators (cell adhesion molecules, chemokines and cytokines) and intracellular signaling pathways have shown beneficial effects in experimental models of DN, decreasing proteinuria and renal lesions. A number of inflammatory molecules have been shown useful to identify diabetic patients at high risk of developing renal complications. In this review, we focus on the key role of inflammation in the genesis and progression of DN, with a special interest in effector molecules and activated intracellular pathways leading to renal damage, as well as a comprehensive update of new therapeutic strategies targeting inflammation to prevent and/or retard renal injury.

Integrated Analysis of the Mechanisms of Da-Chai-Hu Decoction in Type 2 Diabetes Mellitus by a Network Pharmacology Approach

Background

The incidence of type 2 diabetes mellitus (T2DM) has increased year by year, which not only seriously affects people's quality of life, but also imposes a heavy economic burden on the family, society, and country. Currently, the pathogenesis, diagnosis, and treatment of T2DM are still unclear. Therefore, exploration of a precise multitarget treatment strategy is urgent. Here, we attempt to screen out the active components, effective targets, and functional pathways of therapeutic drugs through network pharmacology with taking advantages of traditional Chinese medicine (TCM) formulas for multitarget holistic treatment of diseases to clarify the potential therapeutic mechanism of TCM formulas and provide a systematic and clear thought for T2DM treatment.

Methods

First, we screened the active components of Da-Chai-Hu Decoction (DCHD) by absorption, distribution, metabolism, excretion, and toxicity (ADME/T) calculation. Second, we predicted and screened the active components of DCHD and its therapeutic targets for T2DM relying on the Traditional Chinese Medicine Systems Pharmacology Analysis Platform (TCMSP database) and Text Mining Tool (GoPubMed database), while using the Database for Annotation, Visualization, and Integrated Discovery (DAVID) to obtain T2DM targets. Third, we constructed a network of the active component-target, target-pathway of DCHD using Cytoscape software (http://cytoscape.org/,ver.3.5.1) and then analyzed gene function, related biological processes, and signal pathways through the DAVID database.

Results

We screened 77 active components from 1278 DCHD components and 116 effective targets from 253 ones. After matching the targets of T2DM, we obtained 38 important targets and 7 core targets were selected through further analysis. Through enrichment analysis, we found that these important targets were mainly involved in many biological processes such as oxidative stress, inflammatory reaction, and apoptosis. After analyzing the relevant pathways, the synthetic pathway for the treatment of T2DM was obtained, which provided a diagnosis-treatment idea for DCHD in the treatment of T2DM.

Conclusions

This article reveals the mechanism of DCHD in the treatment of T2DM related to inflammatory response and apoptosis through network pharmacology, which lays a foundation for further elucidation of drugs effective targets.

DR-region of Na+/K+-ATPase is a target to ameliorate hepatic insulin resistance in obese diabetic mice

Reduced hepatic Na⁺/K⁺-ATPase (NKA) activity and NKAα1 expression are engaged in the pathologies of metabolism diseases. The present study was designed to investigate the potential roles of NKAα1 in hepatic gluconeogenesis and glycogenesis in both hepatocytes and obese diabetic mice.

Methods: Insulin resistance was mimicked by glucosamine (GlcN) in either human hepatocellular carcinoma (HepG2) cells or primary mouse primary hepatocytes. Obese diabetic mice were induced by high-fat diet (HFD) feeding for 12 weeks.

Results: We found that both NKA activity and NKAα1 protein level were downregulated in GlcN-treated hepatocytes and in the livers of obese diabetic mice. Pharmacological inhibition of NKA with ouabain worsened, while activation of NKAα1 with an antibody against an extracellular DR region of NKAα1 subunit (DR-Ab) prevented GlcN-induced increase in gluconeogenesis and decrease in glycogenesis. Likewise, the above results were also corroborated by the opposite effects of genetic knockout/overexpression of NKAα1 on both gluconeogenesis and glycogenesis. In obese diabetic mice, hepatic activation or overexpression of NKAα1 stimulated the PI3K/Akt pathway to suppress hyperglycemia and improve insulin resistance. More importantly, loss of NKA activities in NKAα1^+/- mice was associated with more susceptibility to insulin resistance following HFD feeding.

Conclusions: Our findings suggest that NKAα1 is a physiological regulator of glucose homoeostasis and its DR-region is a novel target to treat hepatic insulin resistance.

Screening of the active fractions from the Coreopsis tinctoria Nutt. Flower on diabetic endothelial protection and determination of the underlying mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

The Coreopsis tinctoria Nutt. flower (CTF) has been used traditionally in China for treating hypertension and diabetes as well as reducing body weight and blood fat. However, the vascular protection effect of the CTF has not been studied to date.

AIM OF THE STUDY

This study aimed to screen and identify bioactive fractions from the CTF with a diabetic endothelial protection effect and to clarify the underlying mechanism.

MATERIALS AND METHODS

The vascular protection effect of Fraction A was studied in high-fat diet and streptozocin-induced diabetic models. The endothelial protection effect of Fraction A-2 was further studied in an in vitro vascular endothelial dysfunction model induced by high glucose. In a high glucose-induced human umbilical vein endothelial cell (HUVEC) model, Fractions A-2-2 and A-2-3 were screened, and their detailed mechanisms of endothelial protection were studied. Liquid chromatography mass spectrometry (LC-MS) was used to identify the main components in Fractions A-2-2 and A-2-3.

RESULTS

Fraction A treatment significantly improved the endothelium-dependent vasodilation of the mesenteric artery induced by acetylcholine in diabetic rats. The maximum relaxation was 79.82 ± 2.45% in the control group, 64.36 ± 9.81% in the model group, and 91.87 ± 7.38% in the Fraction A treatment group (P < 0.01). Fraction A treatment also decreased rat tail pressure compared with the model group at the 12th week. The systolic blood pressure was 152.7 5 ± 16.99 mmHg in the control group, 188.50 ± 5.94 mmHg in the model group, and 172.60 ± 14.31 mmHg in the Fraction A treatment group (P < 0.05). The mean blood pressure was 128.50 ± 13.79 mmHg in the control group, 157.00 ± 6.06 mmHg in the model group, and 144.80 ± 11.97 mmHg in the Fraction A treatment group (P < 0.05). In an in vitro vascular endothelium-dependent vasodilation dysfunction model induced by high glucose, Fraction A-2 improved the vasodilation of the mesenteric artery. The maximum relaxation was 82.15 ± 16.24% in the control group, 73.29 ± 14.25% in the model group, and 79.62 ± 13.89% in the Fraction A-2 treatment group (P < 0.05). In a high glucose-induced HUVEC model, Fraction A-2-2 and Fraction A-2-3 upregulated the expression of IRS-1, Akt, and eNOS and increased the levels of p-IRS-1^Ser307, p-Akt ^Ser473, and p-eNOS^Ser1177 and also decreased the expression of NOX4, TNF-α, IL-6, sVCAM, sICAM, and NF-κB (P < 0.01). With the intervention of AG490 and LY294002, the above effects of Fraction A-2-2 and Fraction A-2-3 were inhibited (P < 0.01). LC-MS data showed that in Fraction A-2-2 and Fraction A-2-3, there were 10 main components: flavanocorepsin; polyphenolic; flavanomarein; isochlorogenic acid A; dicaffeoylquinic acid; coreopsin; marein; coreopsin; luteolin-7-O-glucoside; and 3',5,5',7-tetrahydroxyflavanone-O-hexoside.

CONCLUSION

The protective effect of the CTF on diabetic endothelial dysfunction may be due to its effect on the JAK2/IRS-1/PI3K/Akt/eNOS pathway and the related oxidative stress and inflammation. The results strongly suggested that Fraction A-2-2 and Fraction A-2-3 were the active fractions from the CTF, and the CTF might be a potential option for the prevention of vascular complications in diabetes.

Habenula lesions improve glucose metabolism in rats with type 2 diabetes by increasing insulin sensitivity and inhibiting gluconeogenesis

INTRODUCTION

The habenular nucleus (Hb), a famous relay station in the midbrain, is vital for controlling many physiological functions of vertebrates. The role of Hb in the pathogenesis of depression has been thoroughly studied, but whether it functions in the pathogenesis of diabetes remains unknown. In this study, we found that Hb lesions could improve glucose metabolism in type 2 diabetes mellitus (T2DM) by inhibiting the peripheral sympathetic nervous system and hepatic glucose production.

RESEARCH DESIGN AND METHODS

T2DM rats were induced by a high-carbohydrate and fat diet combined with streptozotocin. Electrical lesion method was applied to suppress the function of Hb. Serum and tissue samples of rats in the control group, T2DM group, sham group, and Hb lesion group were detected by ELISA, western blotting, and biochemical methods.

RESULTS

Compared with the sham group, the expression levels of AMPK phosphorylation and insulin receptor (IR) were significantly increased, whereas glucose-6-phosphatase and phosphoenolpyruvate carboxylated kinase were reduced in the liver of the Hb lesion group. In the glucose tolerance test and pyruvate tolerance test, the lesion group showed stronger glucose tolerance and lower hepatic gluconeogenesis than the sham. These results suggest that Hb lesions not only effectively increase insulin sensitivity and improve insulin resistance but also inhibit gluconeogenesis in T2DM rats. Moreover, Hb lesions increase the expression of brain-derived neurotrophic factor, tropomyosin receptor kinase B, glucocorticoid receptor, and IR in the hippocampus. In this study, we also found that Hb lesions increase the content of acetylcholine in the adrenal glands and reduce the content of epinephrine in both the adrenal glands and the liver, which may be the main reason for the Hb lesions to regulate glucose metabolism in the liver.

CONCLUSION

Hb is an important neuroanatomical target for the regulation of glucose metabolism in the central nervous system of diabetic rats.

Polymorphisms in miRNA binding sites involved in metabolic diseases in mice and humans

Type 2 diabetes and obesity are well-studied metabolic diseases, which are based on genetic and epigenetic alterations in combination with an obesogenic lifestyle. The aim of this study was to test whether SNPs in miRNA-mRNA binding sites that potentially disrupt binding, elevate the expression of miRNA targets, which participate in the development of metabolic diseases. A computational approach was developed that integrates transcriptomics, linkage analysis, miRNA-target prediction data, and sequence information of a mouse model of obesity and diabetes. A statistical analysis demonstrated a significant enrichment of 566 genes for a location in obesity- and diabetes-related QTL. They are expressed at higher levels in metabolically relevant tissues presumably due to altered miRNA-mRNA binding sites. Of these, 51 genes harbor conserved and impaired miRNA-mRNA-interactions in human. Among these, 38 genes have been associated to metabolic diseases according to the phenotypes of corresponding knockout mice or other results described in the literature. The remaining 13 genes (e.g. Jrk, Megf9, Slfn8 and Tmem132e) could be interesting candidates and will be investigated in the future.

Knockdown of CTRP6 reduces the deposition of intramuscular and subcutaneous fat in pigs via different signaling pathways

The regulation of porcine subcutaneous (SC) and intramuscular (IM) fat deposition significantly affects pork quality and the lean meat percentage of the carcass, respectively. The adipokine C1q/tumor necrosis factor-related protein 6 (CTRP6), plays a significant role in regulating animal fat deposition. The purpose of this study was to understand the effects of CTRP6 gene knockdown in IM and SC adipocytes by RNA-seq analysis. A total of 1830 and 2936 differentially expressed genes (DEGs) were identified in SC and IM adipocytes, respectively. 844 were down- and 2092 were upregulated in SC adipocytes, while 648 were down- and 1182 were upregulated in IM adipocytes. Furthermore, 1778 DEGs were detected only in SC adipocytes, 672 DEGs only in IM adipocytes, and 1158 DEGs in both types of adipocytes. GO analysis indicated that DEGs involved in adipocyte differentiation were significantly enriched in both SC and IM adipocytes following treatment with CTRP6-siRNA. Moreover, KEGG pathway enrichment analysis revealed differences of metabolic regulation between IM and SC adipocytes. With CTRP6-silencing, the signaling pathways related to Ras and arachidonic acid metabolism were significantly enriched in IM adipocytes, while four other signaling pathways, encompassing the TNF, MAPK, p53 and adipokine pathway were specifically enriched in SC adipocytes. Interestingly, the effect of CTRP6-siRNA treatment was attenuated by the specific Ras activator ML-097 in IM adipocytes, while the specific p53 activator SJ-172550 had the corresponding effect in SC adipocytes. Altogether, we suggest that CTRP6 may be a differential regulator of the development and metabolism of IM and SC adipose tissues.

Interplay between NADH oxidation by complex I, glutathione redox state and sirtuin-3, and its role in the development of insulin resistance

Metabolic diseases are characterized by high NADH/NAD⁺ ratios due to excessive electron supply, causing defective mitochondrial function and impaired sirtuin-3 (SIRT-3) activity, the latter driving to oxidative stress and altered fatty acid β-oxidation. NADH is oxidized by the complex I in the electron transport chain, thereby factors inhibiting complex I like acetylation, cardiolipin peroxidation, and glutathionylation by low GSH/GSSG ratios affects SIRT3 function by increasing the NADH/NAD⁺ ratio. In this review, we summarized the evidence supporting a role of the above events in the development of insulin resistance, which is relevant in the pathogenesis of obesity and diabetes. We propose that maintenance of proper NADH/NAD⁺ and GSH/GSSG ratios are central to ameliorate insulin resistance, as alterations in these redox couples lead to complex I dysfunction, disruption of SIRT-3 activity, ROS production and impaired β-oxidation, the latter two being key effectors of insulin resistance.

Functional Interactomes of Genes Showing Association with Type-2 Diabetes and Its Intermediate Phenotypic Traits Point towards Adipo-Centric Mechanisms in Its Pathophysiology

The pathogenic mechanisms causing type 2 diabetes (T2D) are still poorly understood; a greater awareness of its causation can lead to the development of newer and better antidiabetic drugs. In this study, we used a network-based approach to assess the cellular processes associated with protein–protein interaction subnetworks of glycemic traits—HOMA-β and HOMA-IR. Their subnetworks were further analyzed in terms of their overlap with the differentially expressed genes (DEGs) in pancreatic, muscle, and adipose tissue in diabetics. We found several DEGs in these tissues showing an overlap with the HOMA-β subnetwork, suggesting a role of these tissues in β-cell failure. Many genes in the HOMA-IR subnetwork too showed an overlap with the HOMA-β subnetwork. For understanding the functional theme of these subnetworks, a pathway-to-pathway complementary network analysis was done, which identified various adipose biology-related pathways, containing genes involved in both insulin secretion and action. In conclusion, network analysis of genes showing an association between T2D and its intermediate phenotypic traits suggests their potential role in beta cell failure. These genes enriched the adipo-centric pathways and were expressed in both pancreatic and adipose tissue and, therefore, might be one of the potential targets for future antidiabetic treatment.

Mutual interaction between endoplasmic reticulum and mitochondria in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a common metabolic syndrome. Imbalances between liver lipid output and input are the direct causes of NAFLD, and hepatic steatosis is the pathological premise and basis for NAFLD progression. Mutual interaction between endoplasmic reticulum stress (ERS) and oxidative stress play important roles in NAFLD pathogenesis. Notably, mitochondria-associated membranes (MAMs) act as a structural bridges for functional clustering of molecules, particularly for Ca²⁺, lipids, and reactive oxygen species (ROS) exchange. Previous studies have examined the crucial roles of ERS and ROS in NAFLD and have shown that MAM structural and functional integrity determines normal ER- mitochondria communication. Upon disruption of MAM integrity, miscommunication directly or indirectly causes imbalances in Ca2+ homeostasis and increases ERS and oxidative stress. Here, we emphasize the involvement of MAMs in glucose and lipid metabolism, chronic inflammation and insulin resistance in NAFLD and summarize MAM-targeting drugs and compounds, most of which achieve their therapeutic or ameliorative effects on NAFLD by improving MAM integrity. Therefore, targeting MAMs may be a viable strategy for NAFLD treatment. This review provides new ideas and key points for basic NAFLD research and drug development centred on mitochondria and the endoplasmic reticulum.

Cannabidiol alleviates hemorrhagic shock-induced neural apoptosis in rats by inducing autophagy through activation of the PI3K/AKT pathway

Recently, several studies have reported that the pharmacological effects exerted by cannabidiol (CBD) are partially related to the regulation of autophagy. Increasing evidence indicates that autophagy provides protection against ischemia-induced brain injury. However, the protective effect of CBD against mitochondrial-dependent apoptosis in hemorrhagic shock (HS)-induced brain injury has not been studied. In the present study, we observed the protective effects of CBD against neural mitochondrial-dependent apoptosis in a rat model of HS. In addition, CBD increased Beclin-1 and LC3II expression and reduced P62 expression, which were indicative of autophagy. CBD treatment attenuated the neural apoptosis induced by HS, as reflected by restoring mitochondrial dysfunction, downregulation of BAX, neuro-apoptosis ratio and NF-κB signaling activation, and upregulation of BCL2 in the cerebral cortex. Such protective effects were reversed by 3-Methyladenine, a specific autophagy inhibitor, indicating that the protective effects of CBD treatment involved autophagy. LY294002, a PI3K inhibitor, significantly inhibited CBD-induced autophagy, demonstrating that PI3K/AKT signaling is involved in the CBD's regulation of autophagy. Furthermore, we found that CBD treatment upregulated PI3K/AKT signaling via cannabinoid receptor 1. Therefore, these findings suggested that CBD treatment protects against cerebral injury induced by HS-mediated mitochondrial-dependent apoptosis by activating the PI3K/AKT signaling pathway to reinforce autophagy.

Mechanistic basis for PI3K inhibitor antitumor activity and adverse reactions in advanced breast cancer

PURPOSE

The phosphatidylinositol 3-kinase (PI3K) pathway is involved in several physiological processes, including glucose metabolism, cell proliferation, and cell growth. Hyperactivation of this signaling pathway has been associated with tumorigenesis and resistance to treatment in various cancer types. Mutations that activate PIK3CA, encoding the PI3K isoform p110α, are common in breast cancer, particularly in the hormone receptor-positive (HR+), human epidermal growth factor receptor-2-negative (HER2-) subtype. A number of PI3K inhibitors have been developed and evaluated for potential clinical use in combinations targeting multiple signaling pathways in cancer. The purpose of this review is to provide an overview of PI3K inhibitor mechanisms of action for antitumor activity and adverse events in advanced breast cancer (ABC).

METHODS

Published results from phase 3 trials evaluating the efficacy and safety of PI3K inhibitors in patients with ABC and relevant literature were reviewed.

RESULTS

Although PI3K inhibitors have been shown to prolong progression-free survival (PFS), the therapeutic index is often unfavorable. Adverse events, such as hyperglycemia, rash, and diarrhea are frequently observed in these patients. In particular, hyperglycemia is intrinsically linked to the inhibition of PI3Kα, a key mediator of insulin signaling. Off-target effects, including mood disorders and liver toxicity, have also been associated with some PI3K inhibitors.

CONCLUSION

Recent clinical trial results show that specifically targeting PI3Kα can improve PFS and clinical benefit. Broad inhibition of class I PI3Ks appears to result in an unfavorable safety profile due to off-target effects, limiting the clinical utility of the early PI3K inhibitors.

The gluconeogenic enzyme PCK1 phosphorylates INSIG1/2 for lipogenesis

Cancer cells increase lipogenesis for their proliferation and the activation of sterol regulatory element-binding proteins (SREBPs) has a central role in this process. SREBPs are inhibited by a complex composed of INSIG proteins, SREBP cleavage-activating protein (SCAP) and sterols in the endoplasmic reticulum. Regulation of the interaction between INSIG proteins and SCAP by sterol levels is critical for the dissociation of the SCAP-SREBP complex from the endoplasmic reticulum and the activation of SREBPs^1,2. However, whether this protein interaction is regulated by a mechanism other than the abundance of sterol-and in particular, whether oncogenic signalling has a role-is unclear. Here we show that activated AKT in human hepatocellular carcinoma (HCC) cells phosphorylates cytosolic phosphoenolpyruvate carboxykinase 1 (PCK1), the rate-limiting enzyme in gluconeogenesis, at Ser90. Phosphorylated PCK1 translocates to the endoplasmic reticulum, where it uses GTP as a phosphate donor to phosphorylate INSIG1 at Ser207 and INSIG2 at Ser151. This phosphorylation reduces the binding of sterols to INSIG1 and INSIG2 and disrupts the interaction between INSIG proteins and SCAP, leading to the translocation of the SCAP-SREBP complex to the Golgi apparatus, the activation of SREBP proteins (SREBP1 or SREBP2) and the transcription of downstream lipogenesis-related genes, proliferation of tumour cells, and tumorigenesis in mice. In addition, phosphorylation of PCK1 at Ser90, INSIG1 at Ser207 and INSIG2 at Ser151 is not only positively correlated with the nuclear accumulation of SREBP1 in samples from patients with HCC, but also associated with poor HCC prognosis. Our findings highlight the importance of the protein kinase activity of PCK1 in the activation of SREBPs, lipogenesis and the development of HCC.

Roles of the PI3K/AKT/mTOR signalling pathways in neurodegenerative diseases and tumours

The PI3 K/AKT/mTOR signalling pathway plays an important role in the regulation of signal transduction and biological processes such as cell proliferation, apoptosis, metabolism and angiogenesis. Compared with those of other signalling pathways, the components of the PI3K/AKT/mTOR signalling pathway are complicated. The regulatory mechanisms and biological functions of the PI3K/AKT/mTOR signalling pathway are important in many human diseases, including ischaemic brain injury, neurodegenerative diseases, and tumours. PI3K/AKT/mTOR signalling pathway inhibitors include single-component and dual inhibitors. Numerous PI3K inhibitors have exhibited good results in preclinical studies, and some have been clinically tested in haematologic malignancies and solid tumours. In this review, we briefly summarize the results of research on the PI3K/AKT/mTOR pathway and discuss the structural composition, activation, communication processes, regulatory mechanisms and biological functions of the PI3K/AKT/mTOR signalling pathway in the pathogenesis of neurodegenerative diseases and tumours.

Cancer causes metabolic perturbations associated with reduced insulin-stimulated glucose uptake in peripheral tissues and impaired muscle microvascular perfusion

BACKGROUND

Redirecting glucose from skeletal muscle and adipose tissue, likely benefits the tumor's energy demand to support tumor growth, as cancer patients with type 2 diabetes have 30% increased mortality rates. The aim of this study was to elucidate tissue-specific contributions and molecular mechanisms underlying cancer-induced metabolic perturbations.

METHODS

Glucose uptake in skeletal muscle and white adipose tissue (WAT), as well as hepatic glucose production, were determined in control and Lewis lung carcinoma (LLC) tumor-bearing C57BL/6 mice using isotopic tracers. Skeletal muscle microvascular perfusion was analyzed via a real-time contrast-enhanced ultrasound technique. Finally, the role of fatty acid turnover on glycemic control was determined by treating tumor-bearing insulin-resistant mice with nicotinic acid or etomoxir.

RESULTS

LLC tumor-bearing mice displayed reduced insulin-induced blood-glucose-lowering and glucose intolerance, which was restored by etomoxir or nicotinic acid. Insulin-stimulated glucose uptake was 30-40% reduced in skeletal muscle and WAT of mice carrying large tumors. Despite compromised glucose uptake, tumor-bearing mice displayed upregulated insulin-stimulated phosphorylation of TBC1D4^Thr642 (+18%), AKT^Ser474 (+65%), and AKT^Thr309 (+86%) in muscle. Insulin caused a 70% increase in muscle microvascular perfusion in control mice, which was abolished in tumor-bearing mice. Additionally, tumor-bearing mice displayed increased (+45%) basal (not insulin-stimulated) hepatic glucose production.

CONCLUSIONS

Cancer can result in marked perturbations on at least six metabolically essential functions; i) insulin's blood-glucose-lowering effect, ii) glucose tolerance, iii) skeletal muscle and WAT insulin-stimulated glucose uptake, iv) intramyocellular insulin signaling, v) muscle microvascular perfusion, and vi) basal hepatic glucose production in mice. The mechanism causing cancer-induced insulin resistance may relate to fatty acid metabolism.

Mechanisms of insulin resistance related to white, beige, and brown adipocytes

BACKGROUND

The diminished glucose lowering effect of insulin in obesity, called "insulin resistance," is associated with glucose intolerance, type 2 diabetes, and other serious maladies. Many publications on this topic have suggested numerous hypotheses on the molecular and cellular disruptions that contribute to the syndrome. However, significant uncertainty remains on the mechanisms of its initiation and long-term maintenance.

SCOPE OF REVIEW

To simplify insulin resistance analysis, this review focuses on the unifying concept that adipose tissue is a central regulator of systemic glucose homeostasis by controlling liver and skeletal muscle metabolism. Key aspects of adipose function related to insulin resistance reviewed are: 1) the modes by which specific adipose tissues control hepatic glucose output and systemic glucose disposal, 2) recently acquired understanding of the underlying mechanisms of these modes of regulation, and 3) the steps in these pathways adversely affected by obesity that cause insulin resistance.

MAJOR CONCLUSIONS

Adipocyte heterogeneity is required to mediate the multiple pathways that control systemic glucose tolerance. White adipocytes specialize in sequestering triglycerides away from the liver, muscle, and other tissues to limit toxicity. In contrast, brown/beige adipocytes are very active in directly taking up glucose in response to β adrenergic signaling and insulin and enhancing energy expenditure. Nonetheless, white, beige, and brown adipocytes all share the common feature of secreting factors and possibly exosomes that act on distant tissues to control glucose homeostasis. Obesity exerts deleterious effects on each of these adipocyte functions to cause insulin resistance.

PDCD4 deficiency ameliorates left ventricular remodeling and insulin resistance in a rat model of type 2 diabetic cardiomyopathy

OBJECTIVE

Diabetic cardiomyopathy (DCM) is characterized by cardiac remodeling, dysfunction, and insulin resistance; however, the underlying mechanism has not been fully elucidated. Programmed cell death 4 (PDCD4) is a novel inflammation and apoptosis gene, but its role in type 2 DCM remains elusive. We aimed to determine if PDCD4 intervention improves DCM by affecting left ventricular remodeling, function, and insulin resistance.

RESEARCH DESIGN AND METHODS

We designed a PDCD4^-/- rat, established a type 2 diabetes animal model, and constructed a PDCD4 overexpressed adenovirus and PDCD4 small interfer RNA (siRNA) vectors to alter PDCD4 expression in H9c2 cardiomyocytes. Thereafter, glucose levels, lipid metabolism, echocardiography, and extent of myocardial fibrosis, inflammation, and apoptosis were compared in vivo and in vitro.

RESULTS

PDCD4 deficiency improved insulin resistance, cardiac remodeling, and dysfunction in type 2 DCM rats and improved myocardial hypertrophy, fibrosis, inflammation, and apoptosis. Proliferation and transformation of cardiac fibroblasts was reduced via PDCD4 downregulation in vitro under high-glucose stimulation. Furthermore, PDCD4 regulated the myocardial phosphatidylinositol 3-kinase-protein kinase B (PI3K-AKT) pathway in vivo and in vitro. PDCD4 intervention affected cardiac remodeling, dysfunction, and insulin resistance by influencing fibrosis, inflammation, and apoptosis via the PI3K-AKT pathway in vivo.

CONCLUSIONS

PDCD4 knockdown protected against left ventricular remodeling, dysfunction, and insulin resistance in type 2 DCM rats. The underlying mechanisms may involve reducing cardiomyocyte apoptosis, inflammation, fibrosis, and normalized PI3K-AKT phosphorylation. To the best of our knowledge, our study is the first to report the effects and underlying mechanisms of PDCD4 in type 2 DCM. These results provide a potential new treatment avenue for improving the prognosis of patients with type 2 DCM.

Targeting the Inositol Pyrophosphate Biosynthetic Enzymes in Metabolic Diseases

In mammals, a family of three inositol hexakisphosphate kinases (IP6Ks) synthesizes the inositol pyrophosphate 5-IP7 from IP6. Genetic deletion of Ip6k1 protects mice from high fat diet induced obesity, insulin resistance and fatty liver. IP6K1 generated 5-IP7 promotes insulin secretion from pancreatic β-cells, whereas it reduces insulin signaling in metabolic tissues by inhibiting the protein kinase Akt. Thus, IP6K1 promotes high fat diet induced hyperinsulinemia and insulin resistance in mice while its deletion has the opposite effects. IP6K1 also promotes fat accumulation in the adipose tissue by inhibiting the protein kinase AMPK mediated energy expenditure. Genetic deletion of Ip6k3 protects mice from age induced fat accumulation and insulin resistance. Accordingly, the pan IP6K inhibitor TNP [N2-(m-trifluorobenzyl), N6-(p-nitrobenzyl)purine] ameliorates obesity, insulin resistance and fatty liver in diet induced obese mice by improving Akt and AMPK mediated insulin sensitivity and energy expenditure. TNP also protects mice from bone loss, myocardial infarction and ischemia reperfusion injury. Thus, the IP6K pathway is a potential target in obesity and other metabolic diseases. Here, we summarize the studies that established IP6Ks as a potential target in metabolic diseases. Further studies will reveal whether inhibition of this pathway has similar pleiotropic benefits on metabolic health of humans.

Jowiseungki decoction affects diabetic nephropathy in mice through renal injury inhibition as evidenced by network pharmacology and gut microbiota analyses

Background

Jowiseungki decoction (JSD) is a prescription commonly used for the treatment of diabetic complications or diabetic nephropathy (DN) in traditional medicine clinics. However, the underlying therapeutic mechanisms of JSD are still unclear.

Methods

Streptozotocin (STZ)-induced DN mice were administered 100 and 500 mg/kg JSD for 4 weeks, and the therapeutic mechanisms and targets of JSD were analyzed by network pharmacology and gut microbiota analyses.

Results

JSD significantly decreased the increase in food and water intake, urine volume, fasting blood glucose, serum glucose and triglyceride levels, and urinary albumin excretion. JSD administration significantly increased the decrease in insulin secretion and creatinine clearance and reduced the structural damage to the kidney tissues. Moreover, JSD administration significantly inhibited the expression of protein kinase C-alpha (PKC-α), transforming growth factor beta-1 (TGF-β1), α-smooth muscle actin (α-SMA), nuclear factor-κB (NF-κB), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) in the kidney tissues of DN mice, while it significantly increased the phosphorylation of insulin receptor substrate 1 (IRS-1), phosphatidylinositol-3-kinase (PI3K), and protein kinase B (Akt). In the network pharmacological analysis, JSD obviously influenced phosphatase binding, protein serine/threonine kinase, and mitogen-activated protein kinase (MAPK)-related signaling pathways. Our data suggest that JSD can improve symptoms in STZ-induced DN mice through the inhibition of kidney dysfunction, in particular, by regulating the PKCα/PI3K/Akt and NF-κB/α-SMA signaling pathways. Gut microbiota analysis can help to discover the pharmaco-mechanisms of the influence of JSD on bacterial diversity and flora structures in DN.

Conclusion

JSD can improve the symptoms of DN, and the underlying mechanism of this effect is renal protection through the inhibition of fibrosis and inflammation. JSD can also change bacterial diversity and community structures in DN.

Biliverdin Reductase A (BVRA) Knockout in Adipocytes Induces Hypertrophy and Reduces Mitochondria in White Fat of Obese Mice

Biliverdin reductase (BVR) is an enzymatic and signaling protein that has multifaceted roles in physiological systems. Despite the wealth of knowledge about BVR, no data exist regarding its actions in adipocytes. Here, we generated an adipose-specific deletion of biliverdin reductase-A (BVRA) (Blvra^FatKO) in mice to determine the function of BVRA in adipocytes and how it may impact adipose tissue expansion. The Blvra^FatKO and littermate control (Blvra^Flox) mice were placed on a high-fat diet (HFD) for 12 weeks. Body weights were measured weekly and body composition, fasting blood glucose and insulin levels were quantitated at the end of the 12 weeks. The data showed that the percent body fat and body weights did not differ between the groups; however, Blvra^FatKO mice had significantly higher visceral fat as compared to the Blvra^Flox. The loss of adipocyte BVRA decreased the mitochondrial number in white adipose tissue (WAT), and increased inflammation and adipocyte size, but this was not observed in brown adipose tissue (BAT). There were genes significantly reduced in WAT that induce the browning effect such as Ppara and Adrb3, indicating that BVRA improves mitochondria function and beige-type white adipocytes. The Blvra^FatKO mice also had significantly higher fasting blood glucose levels and no changes in plasma insulin levels, which is indicative of decreased insulin signaling in WAT, as evidenced by reduced levels of phosphorylated AKT (pAKT) and Glut4 mRNA. These results demonstrate the essential role of BVRA in WAT in insulin signaling and adipocyte hypertrophy.

White sweet potato ameliorates hyperglycemia and regenerates pancreatic islets in diabetic mice

Background

White sweet potato (WSP) has many potential beneficial effects on metabolic control and on diabetes-related insulin resistance. The antihyperglycemic effects of Tainung No. 10 (TNG10), a variety of WSP in Taiwan, warrant investigation.

Objective

To investigate the antidiabetic activity of WSP (Ipomoea batatas L. TNG10) and the mechanisms for interventions using whole leaves or tubers of WSP in diabetic mice.

Design

Mice were co-administered with streptozotocin and nicotinamide to induce diabetes and then treated with an experimental diet including either 10% WSP tuber (10%-T) and 30% WSP tuber (30%-T) or 0.5% WSP leaf (0.5%-L) and 5% WSP leaf (5%-L). After 8 weeks’ treatment, their plasma glycemic parameters, lipid profiles, and inflammatory marker were analyzed. Their pancreases were removed for histopathologic image analysis; proteins were also extracted from their muscles for phosphoinositide 3-kinase pathway analysis.

Results

The 30%-T or 5%-L mice had lower plasma glucose, insulin, glucose area under the curve (AUC), homeostatic model assessment of insulin resistance (HOMA-IR), alanine transaminase, triglyceride, and tumor necrosis factor alpha levels. In all diabetic mice, their Langerhans’s area was reduced by 60%; however, after 30% WSP-T or 5% WSP-L diets, the mice demonstrated significant restoration of the Langerhans’s areas (approximately 30%). Only in 5%-L mice, slightly increased expression of insulin-signaling pathway-related proteins, phosphorylated insulin receptor and protein kinase B and membrane glucose transporter 4 was noted.

Conclusions

WSP has antihyperglycemic effects by inducing pancreatic islet regeneration and insulin resistance amelioration. Therefore, WSP has potential applications in dietary diabetes management.

Ultrastructure characterization of pancreatic β-cells is accompanied by modulatory effects of the HDAC inhibitor sodium butyrate on the PI3/AKT insulin signaling pathway in juvenile diabetic rats

Genetic and epigenetic factors contribute equally to the pathogenesis of type 1 diabetes mellitus. Sodium butyrate (NaB) has been reported to improve glucose homeostasis by modulation of the p38/ERK MAPK pathway. This work aims to evaluate the effect of NaB on the ultrastructure of pancreatic β-cells and the PI3/AKT pathway. Juvenile albino male rats were used to establish a type 1 diabetes model using streptozotocin injection and NaB in a pre- and post-treatment schedule. Plasma glucose, insulin levels, and glucose tolerance were evaluated. Light and electron microscopy and immunohistochemistry were performed using Ki-67, caspase-3, and insulin. NaB treatment resulted in a significant improvement in plasma glucose levels, plasma insulin levels/expression, and ameliorated diabetes-induced histological alternations. Additionally, it increased the expression of phosphorylated AKT. These findings provide evidence that NaB may be useful in the treatment of juvenile diabetes.

Triiodothyronine activated extranuclear pathways upregulate adiponectin and leptin in murine adipocytes

Adiponectin and leptin, important for metabolic regulation, are synthesized and secreted by adipose tissue and are influenced by triiodothyronine (T3) that activates the MAPK/ERK and integrin αVβ3 pathways, modulating gene expression. Adipocytes were treated with T3 (10 nM), for 1 h, in the absence or presence of PD98059 (PD) and tetraiodothyroacetic acid (Tetrac), which are pathways inhibitors. The cells were incubated with Adipo Red/Oil Red O reagents, and intracellular lipid accumulation [glycerol and triacylglycerol (TAG)], MTT, 8-hydroxideoxyguanosine (8-OH-dG), and mRNA and protein expression were assessed. T3 increased leptin mRNA and protein expression, and, in contrast, there was a decrease in the Tetrac + T3 group. Adiponectin mRNA expression was not altered by T3, though it had increased its protein expression, which was terminated by inhibitors PD + T3 and Tetrac + T3. However, T3 did not alter PPARγ protein expression, lipid accumulation, TAG, glycerol, and DNA damage, but PD + T3 and Tetrac + T3 reduced these parameters. T3 activated the MAPK/ERK pathway on adipocytes to modulate the adiponectin protein expression and integrin αvβ3 to alter the leptin gene expression.

Evaluation of the epigenetic alterations and gene expression levels of HepG2 cells exposed to zearalenone and α-zearalenol

Zearalenone, produced by various Fusarium species, is a non-steroidal estrogenic mycotoxin that contaminates cereals, resulting in adverse effects on human health. We investigated the effects of zearalenone and its metabolite alpha zearalenol on epigenetic modifications and its relationship with metabolic pathways in human hepatocellular carcinoma cells following 24 h of exposure. Zearalenone and alpha zearalenol at the concentrations of 1, 10 and 50 μM significantly increased global levels of DNA methylation and global histone modifications (H3K27me3, H3K9me3, H3K9ac). Expression levels of the chromatin modifying enzymes EHMT2, ESCO1, HAT1, KAT2B, PRMT6 and SETD8 were upregulated by 50 μM of zearalenone exposure using PCR arrays, consistent with the results of global histone modifications. Zearalenone and alpha zearalenol also changed expression levels of the AhR, LXRα, PPARα, PPARɣ, L-fabp, LDLR, Glut2, Akt1 and HK2 genes, which are related to nuclear receptors and metabolic pathways. PPARɣ, a key regulator of lipid metabolism, was selected from among these genes for further analysis. The PPARɣ promoter reduced methylation significantly following zearalenone exposure. Taken together, the epigenetic mechanisms of DNA methylation and histone modifications may be key mechanisms in zearalenone toxicity. Furthermore, effects of zearalenone in metabolic pathways could be mediated by epigenetic modifications.

Enhancement of glucose homeostasis through the PI3K/Akt signaling pathway by dietary with Agaricus blazei Murrill in STZ-induced diabetic rats

Agaricus blazei Murrill (ABM) is an edible fungus. This study investigated the protective role of ABM fruiting body against streptozotocin (STZ)-induced diabetic rats. After 4 weeks of ABM supplement, glucose homeostasis was improved in diabetic rats. Quantitative real-time and Western blot analyses suggested that ABM could promote the gene and protein expression level of insulin receptor, pyruvate dehydrogenase kinase, phospho-kinase B, kinase B, phosphatidylinositol 3-kinase, insulin receptor substrate 1, glucose transporter-4, and glutamine synthetase, while inhibiting the expression of glycogen synthase kinase 3β and c-jun N-terminal kinase 1 and 2. According to multivariate and univariate statistical analysis, liver metabolite profiles of the normal and diabetic rats fed basal and experimental diet were clearly separated. The differential liver metabolites from diabetic rats fed basal and ABM diet-related pathways including the glycolysis pathway, pentose phosphate pathway, tricarboxylic acid cycle, and oxidative phosphorylation were analyzed. A total of 18 potential biomarker metabolites were identified as differential biomarkers associated with ABM supplement diet.

Anti-obesity effect of plant diterpenes and their derivatives: A review

Obesity is a medical condition in which excess body fat is accumulated by a combination of excessive food intake, lack of physical activity, and genetic susceptibility. Obesity increases the risk of various diseases and conditions, including cardiovascular diseases, diabetes, cancer, and depression. This review focuses on most recent reports pertaining to the antiobesity activity of plant-derived diterpenes in different databases. For this, a search (until August 2019) was conducted in the PubMed and Science Direct databases with the following keywords: "plant diterpenes" or "plant diterpenoids" paired with "obesity" or "antiobesity effects." Overall, 729 references that used the aforementioned keywords were selected, among which 34 articles have been included in this review. Results from this search suggest that a number of diterpenes and their derivatives have been found to exert antiobesity effects through various mechanisms, such as overweight reduction or modification of body mass index, protein-tyrosine phosphatase 1B inhibition, lipase activity inhibition, antiadipogenesis effect, among others. Carnosic acid, carnosol and the derivatives of abietic acid, steviol, and andrographolide are examples of important antiobesity diterpenes and their derivatives. Of note, plant-derived diterpenes may be potential candidates for managing obesity and obesity-related diseases and disorders in human and other animals.

Elucidation of the Mechanisms and Molecular Targets of Sanhuang Xiexin Decoction for Type 2 Diabetes Mellitus Based on Network Pharmacology

Sanhuang Xiexin Decoction (SXD) is commonly used to treat type 2 diabetes mellitus (T2DM) in clinical practice of traditional Chinese medicine (TCM). In order to elucidate the specific analysis mechanisms of SXD for T2DM, the method of network pharmacology was applied to this article. First, the effective ingredients of SXD were obtained and their targets were identified based on the TCMSP database. The T2DM-related targets screened from the GEO database were also collected by comparing the differential expressed genes between T2DM patients and healthy individuals. Then, the common targets in SXD-treated T2DM were obtained by intersecting the putative targets of SXD and the differential expressed genes of T2DM. And the protein-protein interaction (PPI) network was established using the above common targets to screen key genes through protein interactions. Meanwhile, these common targets were used for GO and KEGG analyses to further elucidate how they exert antidiabetic effects. Finally, a gene pathway network was established to capture the core one in common targets enriched in the major pathways to further illustrate the role of specific genes. Based on the data obtained, a total of 67 active compounds and 906 targets of SXD were identified. Four thousand one hundred and seventy-six differentially expressed genes with a P value < 0.005 and ∣log2(fold change) | >0.5 were determined between T2DM patients and control groups. After further screening, thirty-seven common targets related to T2DM in SXD were finally identified. Through protein interactions, the top 5 genes (YWHAZ, HNRNPA1, HSPA8, HSP90AA1, and HSPA5) were identified. It was found that the functional annotations of target genes were associated with oxygen levels, protein kinase regulator, mitochondria, and so on. The top 20 pathways including the PI3K-Akt signaling pathway, cancers, HIF-1 signaling pathway, and JAK-STAT signaling pathway were significantly enriched. CDKN1A was shown to be the core gene in the gene-pathway network, and other several genes such as CCND1, ERBB2, RAF1, EGF, and VEGFA were the key genes for SXD against T2DM. Based on the network pharmacology approach, we identified key genes and pathways related to the prognosis and pathogenesis of T2DM and also provided a feasible method for further studying the chemical basis and pharmacology of SXD.

Extracellular Vesicles Derived from Human Umbilical Cord Mesenchymal Stromal Cells Protect Cardiac Cells Against Hypoxia/Reoxygenation Injury by Inhibiting Endoplasmic Reticulum Stress via Activation of the PI3K/Akt Pathway

Endoplasmic reticulum (ER) stress is implicated in the pathogenesis of many diseases, including myocardial ischemia/reperfusion injury. We hypothesized that human umbilical cord mesenchymal stromal cells derived extracellular vesicles (HuMSC-EVs) could protect cardiac cells against hyperactive ER stress induced by hypoxia/reoxygenation (H/R) injury. The H/R model was generated using the H9c2 cultured cardiac cell line. HuMSC-EVs were extracted using a commercially available exosome isolation reagent. Levels of apoptosis-related signaling molecules and the degree of ER stress were assessed by western blot. The role of the PI3K/Akt pathway was investigated using signaling inhibitors. Lactate dehydrogenase leakage and 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) analysis were used for evaluating the therapeutic effects of HuMSC-EVs in vitro. The results showed that ER stress and the rate of apoptosis were increased in the context of H/R injury. Treatment with HuMSC-EVs inhibited ER stress and increased survival in H9c2 cells exposed to H/R. Mechanistically, the PI3K/Akt pathway was activated by treatment with HuMSC-EVs after H/R. Inhibition of the PI3K/Akt pathway by a specific inhibitor, LY294002, partially reduced the protective effect of HuMSC-EVs. Our findings suggest that HuMSC-EVs could alleviate ER stress-induced apoptosis during H/R via activation of the PI3K/Akt pathway.

Reprogramming of fatty acid metabolism in cancer

A common feature of cancer cells is their ability to rewire their metabolism to sustain the production of ATP and macromolecules needed for cell growth, division and survival. In particular, the importance of altered fatty acid metabolism in cancer has received renewed interest as, aside their principal role as structural components of the membrane matrix, they are important secondary messengers, and can also serve as fuel sources for energy production. In this review, we will examine the mechanisms through which cancer cells rewire their fatty acid metabolism with a focus on four main areas of research. (1) The role of de novo synthesis and exogenous uptake in the cellular pool of fatty acids. (2) The mechanisms through which molecular heterogeneity and oncogenic signal transduction pathways, such as PI3K-AKT-mTOR signalling, regulate fatty acid metabolism. (3) The role of fatty acids as essential mediators of cancer progression and metastasis, through remodelling of the tumour microenvironment. (4) Therapeutic strategies and considerations for successfully targeting fatty acid metabolism in cancer. Further research focusing on the complex interplay between oncogenic signalling and dysregulated fatty acid metabolism holds great promise to uncover novel metabolic vulnerabilities and improve the efficacy of targeted therapies.

Effect of sidt2 Gene on Cell Insulin Resistance and Its Molecular Mechanism

BACKGROUND

Sidt2 (SID1 transmembrane family, member 2) is a multiple transmembrane lysosomal membrane protein newly discovered in our previous study. In the previous study, we used gene targeting technique to make a mouse model of sidt2 gene knockout (sidt2^-/-). It was found that sidt2^-/- mice showed elevated fasting blood glucose and impaired glucose tolerance, showing a disorder of glucose metabolism, suggesting that sidt2 may be closely related to insulin resistance. We used 3T3-L1 adipocytes, C2-C12 myoblasts, and HEPA1-6 hepatoma cells as subjects to observe the effects of sidt2 on insulin-stimulated glucose uptake and the abovementioned insulin signal transduction pathways, and then to explore the effect of sidt2 on peripheral tissue insulin resistance and its possible molecular mechanism.

METHODS

(1) Lentiviruses with sidt2 gene knockout and puromycin resistance were constructed by Crispr/cas9 vector and transfected into 3T3-L1 adipocytes, C2-C12 myoblasts, and HEPA1-6 hepatoma cells to construct sidt2 knockout cell line model. (2) Glucose uptake of 3T3-L1 adipocytes, C2-C12 myoblasts, and HEPA1-6 hepatoma cells stimulated by insulin was detected by glucose detection kit, and the results were analyzed. (3) Sidt2 knockout group and control group of 3T3-L1 adipocytes, C2-C12 myoblast, and HEPA1-6 hepatoma cells were cultured according to the routine method. The total proteins of the above cells were extracted, and the expression of PAKT (thr308), PI3-K, and PIRS-1 (ser307) in the IRS-1 signaling pathway of the three groups was detected by western blot technique.

RESULTS

(1) The sidt2 elimination models of 3T3-L1 adipocytes, C2-C12 myoblasts, and HEPA1-6 hepatoma cells were successfully constructed. (2) It was found that the glucose uptake of cells in the sidt2 knockout group was lower than that in normal group under insulin stimulation through the detection of glucose concentration in the cell culture medium. (3) It was found that the expression of PAKT (thr308) and PI3-K protein decreased and the expression of PIRS-1 (ser307) protein increased in sidt2^-/- group compared to the control group.

CONCLUSIONS

sidt2 knockout can reduce glucose uptake in peripheral tissue under insulin stimulation, which may lead to peripheral tissue insulin resistance by affecting the IRS-1 signal pathway.

Insulin Resistance in Apolipoprotein M Knockout Mice is Mediated by the Protein Kinase Akt Signaling Pathway

BACKGROUND

Previous clinical studies have suggested that apolipoprotein M (apoM) is involved in glucose metabolism and plays a causative role in insulin sensitivity.

OBJECTIVE

The potential mechanism of apoM on modulating glucose homeostasis is explored and differentially expressed genes are analyzed by employing ApoM deficient (ApoM-/- ) and wild type (WT) mice.

METHODS

The metabolism of glucose in the hepatic tissues of high-fat diet ApoM-/- and WT mice was measured by a glycomics approach. Bioinformatic analysis was applied for analyzing the levels of differentially expressed mRNAs in the liver tissues of these mice. The insulin sensitivity of ApoM-/- and WT mice was compared using the insulin tolerance test and the phosphorylation levels of protein kinase Akt (AKT) and insulin stimulation in different tissues were examined by Western blot.

RESULTS

The majority of the hepatic glucose metabolites exhibited lower concentration levels in the ApoM-/- mice compared with those of the WT mice. Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that ApoM deficiency affected the genes associated with the metabolism of glucose. The insulin tolerance test suggested that insulin sensitivity was impaired in ApoM-/- mice. The phosphorylation levels of AKT in muscle and adipose tissues of ApoM-/- mice were significantly diminished in response to insulin stimulation compared with those noted in WT mice.

CONCLUSION

ApoM deficiency led to the disorders of glucose metabolism and altered genes related to glucose metabolism in mice liver. In vivo data indicated that apoM might augment insulin sensitivity by AKT-dependent mechanism.

Sphingolipid Metabolism and Signaling in Skeletal Muscle: From Physiology to Physiopathology

Sphingolipids represent one of the major classes of eukaryotic lipids. They play an essential structural role, especially in cell membranes where they also possess signaling properties and are capable of modulating multiple cell functions, such as apoptosis, cell proliferation, differentiation, and inflammation. Many sphingolipid derivatives, such as ceramide, sphingosine-1-phosphate, and ganglioside, have been shown to play many crucial roles in muscle under physiological and pathological conditions. This review will summarize our knowledge of sphingolipids and their effects on muscle fate, highlighting the role of this class of lipids in modulating muscle cell differentiation, regeneration, aging, response to insulin, and contraction. We show that modulating sphingolipid metabolism may be a novel and interesting way for preventing and/or treating several muscle-related diseases.

Effect of He Qi San on DNA Methylation in Type 2 Diabetes Mellitus Patients with Phlegm-blood Stasis Syndrome

This study was performed to elucidate the potential influence of He Qi San (HQS) on glucose and lipid metabolism in type 2 diabetes mellitus (T2DM) patients with phlegm-blood stasis syndrome (PBSS), and to determine DNA methylation changes. Sixty T2DM patients with PBSS were randomly divided into control and HQS groups. The control group received conventional treatments, and the HQS group received conventional treatments plus HQS. Glucose metabolism (FPG, 2hPG, FINS, and HbA1c) and lipid metabolism indexes (TG, TC and LDL-C) were determined. Genes with differential DNA methylation were subjected to GO and KEGG analyses. Glucose and lipid metabolism indexes in both groups were reduced, but were much more pronounced in the HQS group. Differential promoter CpG methylation regions were identified in 682 genes, including 426 genes with high-CpG promoters, 150 genes with intermediate CpG promoters, and 106 genes with low CpG promoters. Genes with differential DNA methylation were mainly enriched in the AMPK and insulin signaling pathways, terpenoid backbone biosynthesis, and renin secretion. We concluded that HQS remarkably improved indexes of glucose and lipid metabolism in T2DM patients with PBSS through regulating the DNA methylation of genes in the AMPK and insulin signaling pathways and terpenoid backbone biosynthesis.