Pea-derived peptides, VLP, LLP, VA, and LL, improve insulin resistance in HepG2 cells via activating IRS-1/PI3K/AKT and blocking ROS-mediated p38MAPK signaling

HMC Ameliorates Hyperglycemia via Acting PI3K/AKT Pathway and Improving FOXO1 Pathway in ob/ob Mice

Type 2 diabetes is a disease characterized by hyperglycemia and is a growing health problem worldwide. Since many known diabetes drugs are side effects, it is necessary to develop natural substances with guaranteed safety. HM-chromanone isolated from Portulaca oleracea L. is a homoisoflavonoid compound. We investigated the effects of HM-chromanone on hyperglycemia and its mechanism in C57BL/6J ob/ob mice. C57BL/6J-Jms Slc mice were used as the control group, and C57BL/6J-ob/ob mice were divided into three groups: ob/ob (control), metformin (Met; positive control), and HM-chromanone (HMC). Fasting blood glucose was lower in the HMC group than those in the ob/ob group. Insulin resistance was improved by reducing HbA1c, plasma insulin, and HOMA-IR levels in the HMC group. HMC administration decreased the phosphorylation of IRS-1ser307 and increased the phosphorylation of IRS-1tyr612, PI3K, phosphorylation of AKTser⁴⁷³, and PM-GLUT4 in the skeletal muscles of ob/ob mice, indicating improved insulin signaling. HMC administration also increased the phosphorylation of FOXO1 in the liver of ob/ob mice. This inhibited PEPCK and G6pase involved in gluconeogenesis and regulated phosphorylation of glycogen synthase kinase 3β and glycogen synthase involved in glycogen synthesis. In conclusion, HM-chromanone ameliorates hyperglycemia by PI3K/AKT and improves the FOXO1 in ob/ob mice.

Vitamin D ameliorates insulin resistance-induced osteopenia by inactivating the nucleotide-binding oligomerization domain-like receptor protein 3 inflammasome

Objective

Osteoporosis (OP) can be considered a chronic complication of type 2 diabetes mellitus (T2DM). Aberrant activation of the nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome is associated with the pathogenesis of various inflammation-related diseases, e.g., T2DM and OP. Vitamin D affects the inflammatory pathway and inhibits an excessive inflammatory response. The current study investigated the inter-relationship between vitamin D and inflammasome activation in T2DM.

Method

Hepatocellular carcinoma (HepG2) cells and bone marrow stromal cells (BMSCs) were treated with Conditioned Medium of bone marrow mesenchymal stem cells after VitD treatment (CM-VitD), as well as phosphoinositide 3-kinase (PI3K) specific agonist, 740Y-P, or the PI3K specific inhibitor, LY294002, respectively, or both. 40 Eight-week-old female Sprague Dawley rats were selected and established as a DM model. The rats were injected with CM-VitD, as well as the 740Y-P specific agonist, or the LY294002 inhibitor, respectively, or both. A quantitative reverse transcription polymerase chain reaction and western blotting were conducted to evaluate the expression of messenger ribonucleic acid and protein in the RUX2 gene, alkaline phosphatase (ALP), OsteoPontiN (OPN), peroxisome proliferator-activated receptor gamma (PPARγ), fatty acid-binding protein 4 (FABP4), protein kinase B (AKT), PI3K, NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), caspase-1, interleukin (IL)-1 beta (β), IL-18, and tumor necrosis factor alpha (TNF-α) in the BMSCs and liver tissue of rats. Enzyme-linked immunosorbent assay was used to detect the concentration of inflammatory factors in the cell supernatant and serum of rats.

Results

An isolated co-culture of HepG2/insulin-resistance cells and BMSCs promoted the adipogenic transformation of the latter and inhibited the transformation of BMSCs into osteogenesis. The PI3K specific agonist, 740Y-P, significantly increased the expression of PI3K, AKT, NLRP3, ASC and Caspase-1 while the PI3K specific inhibitor, LY294002, does the opposite. Additionally, CM-VitD reduced the expression of NLRP3, ASC, caspase-1, IL-1β, and IL-18 in BMSCs and rat liver via the PI3K/AKT pathway.

Conclusion

Vitamin D can inhibit the inflammatory response induced by T2DM and promote the osteogenesis of BMSCs, which may play a key role in the treatment of type 2 diabetes patients with OP.

Anti-fatigue effects of fermented soybean protein peptides in mice

BACKGROUND

Bioactive protein hydrolysates and peptides are believed to help counteract and ameliorate physical fatigue. Fermented soybean protein peptides (FSPPs) were prepared by protease hydrolysis and microbial fermentation. The present study aimed to evaluate the anti-fatigue properties of FSPPs.

RESULTS

The forced swimming time in the FSPP group was 35.78% longer than the control group, the oxygen-resistant survival time of the FSPP group was significantly prolonged and the prolongation rate was 31.00%. In addition, FSPPs decreased the lactic acid (LD), blood urea nitrogen (BUN) and creatine kinase (CK) concentration by 27.47%, 25.93% and 21.70%, respectively, after treatment, while increasing the levels of liver glycogen and muscle glycogen by 93.35% and 67.31%, respectively. FSPPs can significantly increase gut microbiota diversity and regulate the species richness of gut microbiota. The results of real-time polymerase chain reaction (RT-PCR) and western blotting showed that FSPPs activate p-AMPK/PGC1-α and PI3K/Akt/mTOR signaling pathways.

CONCLUSION

These results indicate that treatment with FSPPs induces anti-fatigue effects, which may be due to the mediating muscle protein synthesis and participation in skeletal muscle hypertrophy, providing energy for muscle cells. FSPPs may have potential applications in the food industry as functional material additives. © 2021 Society of Chemical Industry.

A comprehensive review on the glucoregulatory properties of food-derived bioactive peptides

Diabetes mellitus, a group of metabolic disorders characterized by persistent hyperglycemia, affects millions of people worldwide and is on the rise. Dietary proteins, from a wide range of food sources, are rich in bioactive peptides with antidiabetic properties. Notable examples include AGFAGDDAPR, a black tea-derived peptide, VRIRLLQRFNKRS, a β-conglycinin-derived peptide, and milk-derived peptide VPP, which have shown antidiabetic effects in diabetic rodent models through variety of pathways including improving beta-cells function, suppression of alpha-cells proliferation, inhibiting food intake, increasing portal cholecystokinin concentration, enhancing insulin signaling and glucose uptake, and ameliorating adipose tissue inflammation. Despite the immense research on glucoregulatory properties of bioactive peptides, incorporation of these bioactive peptides in functional foods or nutraceuticals is widely limited due to the existence of several challenges in the field of peptide research and commercialization. Ongoing research in this field, however, is fundamental to pave the road for this purpose.

Platelet-Activating Factor Promotes the Development of Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a multifaceted clinicopathological syndrome characterised by excessive hepatic lipid accumulation that causes steatosis, excluding alcoholic factors. Platelet-activating factor (PAF), a biologically active lipid transmitter, induces platelet activation upon binding to the PAF receptor. Recent studies have found that PAF is associated with gamma-glutamyl transferase, which is an indicator of liver disease. Moreover, PAF can stimulate hepatic lipid synthesis and cause hypertriglyceridaemia. Furthermore, the knockdown of the PAF receptor gene in the animal models of NAFLD helped reduce the inflammatory response, improve glucose homeostasis and delay the development of NAFLD. These findings suggest that PAF is associated with NAFLD development. According to reports, patients with NAFLD or animal models have marked platelet activation abnormalities, mainly manifested as enhanced platelet adhesion and aggregation and altered blood rheology. Pharmacological interventions were accompanied by remission of abnormal platelet activation and significant improvement in liver function and lipids in the animal model of NAFLD. These confirm that platelet activation may accompany a critical importance in NAFLD development and progression. However, how PAFs are involved in the NAFLD signalling pathway needs further investigation. In this paper, we review the relevant literature in recent years and discuss the role played by PAF in NAFLD development. It is important to elucidate the pathogenesis of NAFLD and to find effective interventions for treatment.

Pea Proteins Have Anabolic Effects Comparable to Milk Proteins on Whole Body Protein Retention and Muscle Protein Metabolism in Old Rats

Plant proteins are attracting rising interest due to their pro-health benefits and environmental sustainability. However, little is known about the nutritional value of pea proteins when consumed by older people. Herein, we evaluated the digestibility and nutritional efficiency of pea proteins compared to casein and whey proteins in old rats. Thirty 20-month-old male Wistar rats were assigned to an isoproteic and isocaloric diet containing either casein (CAS), soluble milk protein (WHEY) or Pisane™ pea protein isolate for 16 weeks. The three proteins had a similar effect on nitrogen balance, true digestibility and net protein utilization in old rats, which means that different protein sources did not alter body composition, tissue weight, skeletal muscle protein synthesis or degradation. Muscle mitochondrial activity, inflammation status and insulin resistance were similar between the three groups. In conclusion, old rats used pea protein with the same efficiency as casein or whey proteins, due to its high digestibility and amino acid composition. Using these plant-based proteins could help older people diversify their protein sources and more easily achieve nutritional intake recommendations.

miR-140-5p Aggravates Insulin Resistance via Directly Targeting GYS1 and PPP1CC in Insulin-Resistant HepG2 Cells

BACKGROUND

Much attention has been paid to the regulatory role of microRNA (miRNA) in insulin resistance. Nevertheless, how miR-140-5p regulates insulin resistance remains unclear. In this research, we aim to investigate the roles of miR-140-5p in insulin resistance.

METHODS

qRT-PCR is used to analyze the expression level of miR-140-5p in insulin-resistant HepG2 cells. Glucose consumption and glucose uptake are detected to study the effect of miR-140-5p knockdown in insulin-resistant HepG2 cells and miR-140-5p overexpression in HepG2 cells. Bioinformatic analysis, luciferase reporter assay and confirmatory experiments are applied to identify the target gene bound with miR-140-5p and study the effect of miR-140-5p on the downstream substrates of target genes. Rescue experiments have verified the roles of miR-140-5p and target gene in glucose metabolism.

RESULTS

The expression level of miR-140-5p was upregulated in insulin-resistant HepG2 cells and was significantly correlated with cellular glucose metabolism. Functionally, miR-140-5p overexpression induced impairment of glucose consumption and glucose uptake. Besides, bioinformatics analysis indicated that glycogen synthetase (GYS1) and protein phosphatase 1 catalytic subunit gamma (PPP1CC) were the target genes of miR-140-5p. Western blotting and qRT-PCR results revealed a negative correlation between GYS1, PPP1CC and miR-140-5p. The glycogen detection results showed that miR140-5p inhibited the production of the downstream substrates of the target gene. Rescue experiments showed that inhibition of GYS1 or PPP1CC partially enhanced the insulin-resistant effects of miR-140-5p knockdown in insulin-resistant HepG2 cells.

CONCLUSION

miR-140-5p overexpression augments the development of insulin resistance and miR-140-5p may be served as a therapeutic target of metabolic diseases.