BACKGROUND: Pancreatic β-cells elevate insulin production and secretion through a compensatory mechanism to override insulin resistance under metabolic stress conditions. Deficits in β-cell compensatory capacity result in hyperglycemia and type 2 diabetes (T2D). However, the mechanism in the regulation of β-cell compensative capacity remains elusive. Nuclear factor-Y (NF-Y) is critical for pancreatic islets' homeostasis under physiological conditions, but its role in β-cell compensatory response to insulin resistance in obesity is unclear. METHODS: In this study, using obese ( ob/ob ) mice with an absence of NF-Y subunit A (NF-YA) in β-cells ( ob , Nf-ya βKO) as well as rat insulinoma cell line (INS1)-based models, we determined whether NF-Y-mediated apoptosis makes an essential contribution to β-cell compensation upon metabolic stress. RESULTS: Obese animals had markedly augmented NF-Y expression in pancreatic islets. Deletion of β-cell Nf-ya in obese mice worsened glucose intolerance and resulted in β-cell dysfunction, which was attributable to augmented β-cell apoptosis and reactive oxygen species (ROS). Furthermore, primary pancreatic islets from Nf-ya βKO mice were sensitive to palmitate-induced β-cell apoptosis due to mitochondrial impairment and the attenuated antioxidant response, which resulted in the aggravation of phosphorylated c-Jun N-terminal kinase (JNK) and cleaved caspase-3. These detrimental effects were completely relieved by ROS scavenger. Ultimately, forced overexpression of NF-Y in INS1 β-cell line could rescue palmitate-induced β-cell apoptosis, dysfunction, and mitochondrial impairment. CONCLUSION Pancreatic NF-Y might be an essential regulator of β-cell compensation under metabolic stress.
Rats ; Mice ; Animals ; Reactive Oxygen Species/metabolism* ; Diabetes Mellitus, Type 2/metabolism* ; Insulin Resistance ; Insulin ; Insulin-Secreting Cells/metabolism* ; Apoptosis ; Stress, Physiological ; Transcription Factors/metabolism* ; Palmitates/pharmacology* ; Obesity/metabolism*

Branched chain amino acids, as essential amino acids, can be used to synthesize nitrogen-containing compounds and also act as signal molecules to regulate substance metabolism. Studies have shown that the elevated level of branched chain amino acids is closely related to insulin resistance and type 2 diabetes. It can affect insulin signal transduction by activating mammalian target of rapamycin (mTOR) signal pathway, and regulate insulin resistance by damaging lipid metabolism and affecting mitochondrial function. In addition, abnormal catabolism of branched amino acids can lead to the accumulation of metabolic intermediates, such as branched chain α-keto acids, 3-hydroxyisobutyrate and β-aminoisobutyric acid. Branched chain α-keto acids and 3-hydroxyisobutyrate can induce insulin resistance by affecting insulin signaling pathway and damaging lipid metabolism. β-aminoisobutyric acid can improve insulin resistance by reducing lipid accumulation and inflammatory reaction and enhancing fatty acid oxidation. This paper systematically reviewed the regulatory effects and mechanisms of branched chain amino acids and their metabolic intermediates on insulin resistance, which will provide a new direction for the prevention and treatment of insulin resistance and type 2 diabetes.
Humans ; Amino Acids, Branched-Chain/metabolism* ; Insulin Resistance/physiology* ; Diabetes Mellitus, Type 2 ; Insulin/pharmacology* ; Keto Acids/metabolism*

OBJECTIVES: To investigate the effects and molecular mechanisms of asiatic acid on β-cell function in type 2 diabetes mellitus (T2DM). METHODS: The T2DM model was established by high fat diet and streptozotocin injection in ICR mice, and the effects of asiatic acid on glucose regulation were investigated in model mice. The islets were isolated from palmitic acid-treated diabetic mice. ELISA was used to detect the glucose-stimulated insulin secretion, tumor necrosis factor (TNF)-α and interleukin (IL)-6. ATP assay was applied to measure ATP production, and Western blotting was used to detect protein expression of mature β cell marker urocortin (Ucn) 3 and mitofusin (Mfn) 2. The regulatory effects of asiatic acid on glucose-stimulated insulin secretion (GSIS) and Ucn3 expression were also investigated after siRNA interference with Mfn2 or treatment with TNF-α. RESULTS: Asiatic acid with the dose of 25 mg·kg^－1·d^－1 had the best glycemic control in T2DM mice and improved the homeostasis model assessment β index. Asiatic acid increased the expression of Mfn2 and Ucn3 protein and improved the GSIS function of diabetic β cells in vitro and in vivo (both P<0.05). Moreover, it improved the ATP production of islets of T2DM mice in vitro (P<0.05). Interfering Mfn2 with siRNA blocked the up-regulation of Ucn3 and GSIS induced by asiatic acid. Asiatic acid inhibited islet TNF-α content and increased Mfn2 and Ucn3 protein expression inhibited by TNF-α. CONCLUSIONS Asiatic acid improves β cell insulin secretion function in T2DM mice by maintaining the β cell maturity, which may be related to the TNF-α/Mfn2 pathway.
Mice ; Animals ; Insulin Secretion ; Diabetes Mellitus, Type 2/drug therapy* ; Islets of Langerhans/metabolism* ; Tumor Necrosis Factor-alpha/metabolism* ; Insulin/therapeutic use* ; Diabetes Mellitus, Experimental ; Mice, Inbred ICR ; Glucose/therapeutic use* ; Interleukin-6/metabolism* ; RNA, Small Interfering/pharmacology* ; Adenosine Triphosphate ; GTP Phosphohydrolases/therapeutic use*

OBJECTIVES: Endothelium-dependent vasodilation dysfunction is the pathological basis of diabetic macroangiopathy. The utilization and adaptation of endothelial cells to high glucose determine the functional status of endothelial cells. Glycolysis pathway is the major energy source for endothelial cells. Abnormal glycolysis plays an important role in endothelium-dependent vasodilation dysfunction induced by high glucose. Pyruvate kinase isozyme type M2 (PKM2) is one of key enzymes in glycolysis pathway, phosphorylation of PKM2 can reduce the activity of pyruvate kinase and affect the glycolysis process of glucose. TEPP-46 can stabilize PKM2 in its tetramer form, reducing its dimer formation and phosphorylation. Using TEPP-46 as a tool drug to inhibit PKM2 phosphorylation, this study aims to explore the impact and potential mechanism of phosphorylated PKM2 (p-PKM2) on endothelial dependent vasodilation function in high glucose, and to provide a theoretical basis for finding new intervention targets for diabetic macroangiopathy. METHODS: The mice were divided into 3 groups: a wild-type (WT) group (a control group, C57BL/6 mice) and a db/db group (a diabetic group, db/db mice), which were treated with the sodium carboxymethyl cellulose solution (solvent) by gavage once a day, and a TEPP-46 group (a treatment group, db/db mice+TEPP-46), which was gavaged with TEPP-46 (30 mg/kg) and sodium carboxymethyl cellulose solution once a day. After 12 weeks of treatment, the levels of p-PKM2 and PKM2 protein in thoracic aortas, plasma nitric oxide (NO) level and endothelium-dependent vasodilation function of thoracic aortas were detected. High glucose (30 mmol/L) with or without TEPP-46 (10 μmol/L), mannitol incubating human umbilical vein endothelial cells (HUVECs) for 72 hours, respectively. The level of NO in supernatant, the content of NO in cells, and the levels of p-PKM2 and PKM2 protein were detected. Finally, the effect of TEPP-46 on endothelial nitric oxide synthase (eNOS) phosphorylation was detected at the cellular and animal levels. RESULTS: Compared with the control group, the levels of p-PKM2 in thoracic aortas of the diabetic group increased (P<0.05). The responsiveness of thoracic aortas in the diabetic group to acetylcholine (ACh) was 47% lower than that in the control group (P<0.05), and that in TEPP-46 treatment group was 28% higher than that in the diabetic group (P<0.05), while there was no statistically significant difference in the responsiveness of thoracic aortas to sodium nitroprusside (SNP). Compared with the control group, the plasma NO level of mice decreased in the diabetic group, while compared with the diabetic group, the phosphorylation of PKM2 in thoracic aortas decreased and the plasma NO level increased in the TEPP-46 group (both P<0.05). High glucose instead of mannitol induced the increase of PKM2 phosphorylation in HUVECs and reduced the level of NO in supernatant (both P<0.05). HUVECs incubated with TEPP-46 and high glucose reversed the reduction of NO production and secretion induced by high glucose while inhibiting PKM2 phosphorylation (both P<0.05). At the cellular and animal levels, TEPP-46 reversed the decrease of eNOS (ser1177) phosphorylation induced by high glucose (both P<0.05). CONCLUSIONS p-PKM2 may be involved in the process of endothelium-dependent vasodilation dysfunction in Type 2 diabetes by inhibiting p-eNOS (ser1177)/NO pathway.
Animals ; Humans ; Mice ; Carboxymethylcellulose Sodium/pharmacology* ; Diabetes Mellitus, Type 2/metabolism* ; Endothelium, Vascular/metabolism* ; Glucose/metabolism* ; Human Umbilical Vein Endothelial Cells ; Mice, Inbred C57BL ; Nitric Oxide/metabolism* ; Nitric Oxide Synthase Type III/metabolism* ; Phosphorylation ; Pyruvate Kinase/metabolism* ; Vasodilation

Objective: To investigate whether tanshinone ⅡA can protect the apoptosis of mice cochlear pericytes induced by high glucose and its specific protective mechanism, so as to provide experimental evidence for the prevention and treatment of diabetic hearing loss. Methods: C57BL/6J male mice were used to prepare type 2 diabetes model, which were divided into normal (NG) group, diabetic (DM) group, diabetic+tanshinone ⅡA (HG+tanshinone ⅡA) group and tanshinone ⅡA group. Each group had 10 animals. Primary cochlear pericytes were divided into NG group, HG group (high glucose 35 mmol/L), HG+tanshinone ⅡA (1, 3, 5 μmol/L) group, HG+Tanshinone ⅡA+LY294002 (PI3K/AKT pathway inhibitor) group, LY294002 group, tanshinone ⅡA group and DMSO group. Auditory brainstem response (ABR) was used to measure hearing threshold. Evans blue was used to detect the permeability of blood labyrinth barrier in each group. TBA methods were used to detect oxidative stress levels in various organs of mice. Morphological changes of stria vascularis were observed by hematoxylin-eosin staining (HE). Evans blue was used to detect the vascular labyrinth barrier permeability in cochlea. The expression of apoptosis protein in stria vascularis pericytes was observed by immunofluorescence. Pericytes apoptosis rate was observed by flow cytometry. DCFH-DA was combined with flow cytometry to detect intracellular ROS content, and Western blot was used to detect the expression of apoptotic proteins (Cleaved-caspase3, Bax), anti-apoptotic proteins (BCL-2) and pathway proteins (PI3K, p-PI3K, AKT, p-AKT). SPSS software was used for statistical analysis. Independent sample t test was performed, and P<0.05 was considered statistically significant. Results: Animal experiments: Tanshinone ⅡA decreased the hearing threshold of DM group [(35.0±3.5) dB SPL vs. (55.3±8.1) dB SPL] (t=4.899, P<0.01), decreased the oxidative stress level in cochlea (t=4.384, P<0.05), improved the structure disorder, atrophy of cochlea vascular lines, vacuole increased phenomenon. Tanshinone ⅡA alleviated the increased permeability of the blood labyrinth barrier [Evans blue leakage (6.84±0.27) AU vs. (8.59±0.85) AU] in the cochlea of DM mice (t=2.770, P<0.05), reversed the apoptotic protein: Caspase3 (t=4.956, P<0.01) and Bax (t=4.388, P<0.05) in cochlear vascularis. Cell experiments: Tanshinone ⅡA decreased intracellular ROS content in a concentration-dependent way (t=3.569, P<0.05; t=4.772, P<0.01; t=7.494, P<0.01); Tanshinone ⅡA decreased apoptosis rate and apoptotic protein, and increased the expression of anti-apoptotic protein, p-PI3K/PI3K and p-AKT/AKT in concentration-dependent manner (all P values<0.05); LY294002 reversed the protective effect of tanshinone ⅡA on pericytes apoptosis (all P values<0.05). Conclusion: Tanshinone ⅡA can inhibit the apoptosis of cochlear pericytes induced by high glucose by reducing oxidative stress level and activating PI3K/AKT signaling pathway under high glucose environment, thus playing a protective role in diabetic hearing loss.
Animals ; Male ; Mice ; Apoptosis ; bcl-2-Associated X Protein ; Diabetes Mellitus, Type 2 ; Evans Blue ; Glucose ; Hearing Loss ; Mice, Inbred C57BL ; Pericytes/metabolism* ; Phosphatidylinositol 3-Kinases/metabolism* ; Proto-Oncogene Proteins c-akt/metabolism* ; Reactive Oxygen Species/metabolism* ; Signal Transduction

OBJECTIVES: The excretion of urinary vitamin D-binding protein (uVDBP) is related to the occurrence and development of early-stage renal damage in patients with Type 2 diabetes (T2DM). This study aims to explore the significance of detecting uVDBP in T2DM patients and its relationship with renal tubules, and to provide a new direction for the early diagnosis of T2DM renal damage. METHODS: A total of 105 patients with T2DM, who met the inclusion criteria, were included as a patient group, and recruited 30 individuals as a normal control group. The general information and blood and urine biochemical indicators of all subjects were collected; the levels of uVDBP, and a marker of tubular injury [urine kidney injury molecule 1 (uKIM-1), urine neutrophil gelatinase-associated lipocalin (uNGAL) and urine retinol-binding protein (uRBP)] were detected by enzyme-linked immunosorbent assay. The results were corrected by urinary creatinine (Cr) to uVDBP/Cr, uKIM-1/Cr, uNGAL/Cr and uRBP/Cr. The Pearson's and Spearman's correlation tests were used to analyze the correlation between uVDBP/Cr and urine albumin-to-creatinine ratio (UACR), estimated glomerular filtration rate (eGFR) and markers of tubular injury, and multivariate linear regression and receiver operating characteristic curve were used to analyze the correlation between uVDBP/Cr and UACR or eGFR. RESULTS: Compared with the normal control group, the uVDBP/Cr level in the patient group was increased (P<0.05), and which was positively correlated with UACR (r=0.774, P<0.01), and negatively correlated with eGFR (r=-0.397, P<0.01). There were differences in the levels of uKIM-1/Cr, uNGAL/Cr, and uRBP/Cr between the 2 groups (all P<0.01). The uVDBP/Cr was positively correlated with uKIM-1/Cr (r=0.752, P<0.01), uNGAL/Cr (r=0.644, P<0.01) and uRBP/Cr (r=0.812, P<0.01). The sensitivity was 90.0% and the specificity was 82.9% (UACR>30 mg/g) for evaluation of uVDBP/Cr on T2DM patients with early-stage renal damage, while the sensitivity was 75.0% and the specificity was 72.6% for evaluation of eGFR on T2DM patients with early-stage renal damage. CONCLUSIONS The uVDBP/Cr can be used as a biomarker in early-stage renal damage in T2DM patients.
Humans ; Diabetes Mellitus, Type 2/complications* ; Creatinine ; Vitamin D-Binding Protein/urine* ; Lipocalin-2/urine* ; Kidney/metabolism* ; Glomerular Filtration Rate ; Biomarkers

The failure rate of dental implantation in patients with well-controlled type 2 diabetes mellitus (T2DM) is higher than that in non-diabetic patients. This due, in part, to the impaired function of bone marrow mesenchymal stem cells (BMSCs) from the jawbone marrow of T2DM patients (DM-BMSCs), limiting implant osseointegration. RNA N6-methyladenine (m6A) is important for BMSC function and diabetes regulation. However, it remains unclear how to best regulate m6A modifications in DM-BMSCs to enhance function. Based on the "m6A site methylation stoichiometry" of m6A single nucleotide arrays, we identified 834 differential m6A-methylated genes in DM-BMSCs compared with normal-BMSCs (N-BMSCs), including 43 and 790 m6A hypermethylated and hypomethylated genes, respectively, and 1 gene containing hyper- and hypomethylated m6A sites. Differential m6A hypermethylated sites were primarily distributed in the coding sequence, while hypomethylated sites were mainly in the 3'-untranslated region. The largest and smallest proportions of m6A-methylated genes were on chromosome 1 and 21, respectively. MazF-PCR and real-time RT-PCR results for the validation of erythrocyte membrane protein band 4.1 like 3, activity-dependent neuroprotector homeobox (ADNP), growth differentiation factor 11 (GDF11), and regulator of G protein signalling 2 agree with m6A single nucleotide array results; ADNP and GDF11 mRNA expression decreased in DM-BMSCs. Furthermore, gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses suggested that most of these genes were enriched in metabolic processes. This study reveals the differential m6A sites of DM-BMSCs compared with N-BMSCs and identifies candidate target genes to enhance BMSC function and improve implantation success in T2DM patients.
Humans ; Bone Marrow/metabolism* ; Bone Morphogenetic Proteins/metabolism* ; Dental Implants/adverse effects* ; Diabetes Mellitus, Type 2/metabolism* ; Growth Differentiation Factors/metabolism* ; Mesenchymal Stem Cells/metabolism* ; RNA/metabolism* ; RNA Processing, Post-Transcriptional

Intestinal flora and its metabolites are closely related to the progression of type 2 diabetes mellitus(T2DM). Eubacterium is one of the dominant intestinal flora, and its metabolites short-chain fatty acids (SCFAs) play a leading role in regulating intestinal metabolic balance. It has been reported that SCFAs can regulate the secretion of glucagon-like peptide-1, improve the function of pancreatic β cells, participate in bile acids metabolism and regulate the production of inflammatory factors in T2DM. Based on the above research background, this article mainly reviews the relationship between Eubacterium and its metabolite SCFAs and T2DM and its regulatory mechanism.
Humans ; Diabetes Mellitus, Type 2 ; Eubacterium/metabolism* ; Fatty Acids, Volatile/metabolism* ; Gastrointestinal Microbiome

Metformin has been used for the treatment of type II diabetes mellitus for decades due to its safety, low cost, and outstanding hypoglycemic effect clinically. The mechanisms underlying these benefits are complex and still not fully understood. Inhibition of mitochondrial respiratory-chain complex I is the most described downstream mechanism of metformin, leading to reduced ATP production and activation of AMP-activated protein kinase (AMPK). Meanwhile, many novel targets of metformin have been gradually discovered. In recent years, multiple pre-clinical and clinical studies are committed to extend the indications of metformin in addition to diabetes. Herein, we summarized the benefits of metformin in four types of diseases, including metabolic associated diseases, cancer, aging and age-related diseases, neurological disorders. We comprehensively discussed the pharmacokinetic properties and the mechanisms of action, treatment strategies, the clinical application, the potential risk of metformin in various diseases. This review provides a brief summary of the benefits and concerns of metformin, aiming to interest scientists to consider and explore the common and specific mechanisms and guiding for the further research. Although there have been countless studies of metformin, longitudinal research in each field is still much warranted.
Humans ; Metformin/pharmacokinetics* ; Diabetes Mellitus, Type 2/metabolism* ; Hypoglycemic Agents/pharmacology* ; AMP-Activated Protein Kinases/metabolism* ; Aging

OBJECTIVES: To observe the effects on the glucose-lipid metabolism and the expression of zinc-α2-glycoprotein (ZAG) and glucose transporter 4 (GLUT4) in the femoral quadriceps and adipose tissue after electroacupuncture (EA) at "Pishu" (BL 20), "Weiwanxiashu" (EX-B 3), "Zusanli" (ST 36) and "Sanyinjiao" (SP 6) in the rats with diabetes mellitus type 2 (T2DM), so as to explore the effect mechanism of EA in treatment of T2DM. METHODS: Twelve ZDF male rats were fed with high-sugar and high-fat fodder, Purina #5008 for 4 weeks to induce T2DM model. After successfully modeled, the rats were randomly divided into a model group and an EA group, with 6 rats in each one. Additionally, 6 ZL male rats of the same months age were collected as the blank group. The rats in the EA group were treated with EA at bilateral "Pishu" (BL 20), "Weiwanxiashu" (EX-B 3), "Zusanli" (ST 36) and "Sanyinjiao" (SP 6), with continuous wave, 15 Hz in frequency, and 2 mA in intensity. The electric stimulation lasted 20 min each time. EA was delivered once daily, 6 times a week for 4 weeks. Separately, the levels of fasting blood glucose (FBG) was measured before modeling, before and after intervention, and the body mass of each rat was weighted before and after intervention. After intervention, the levels of the total cholesterol (TC), triacylglycerol (TG) and free fatty acid (FFA) in serum were detected using enzyme colorimetric method; and the levels of the serum insulin (INS) and ZAG were detected by ELISA. Besides, the insulin sensitivity index (HOMA-ISI) was calculated. With Western blot technique adopted, the protein expressions of ZAG and GLUT4 in the femoral quadriceps and adipose tissue were determined. RESULTS: After intervention, compared with the blank group, the levels of FBG and body mass, and the levels of serum TC, TG, FFA and INS increased (P<0.01), while HOMA-ISI decreased (P<0.01); the level of ZAG in the serum and the protein expressions of ZAG and GLUT4 in the femoral quadriceps and adipose tissue dropped (P<0.01) in the model group. In the EA group, compared with the model group, the levels of FBG and body mass, and the levels of serum TC, TG, FFA and INS were reduced (P<0.01), and HOMA-ISI increased (P<0.01); the level of ZAG in the serum and the protein expressions of ZAG and GLUT4 in the femoral quadriceps and adipose tissue increased (P<0.01, P<0.05). CONCLUSIONS Electroacupuncture can effectively regulate glucose-lipid metabolism, improve insulin resistance and sensitivity in the rats with T2DM, which is associated with the modulation of ZAG and GLUT4 expression in the skeletal muscle and adipose tissue.
Rats ; Male ; Animals ; Glucose/metabolism* ; Electroacupuncture ; Rats, Sprague-Dawley ; Diabetes Mellitus, Type 2/therapy* ; Lipid Metabolism ; Triglycerides ; Adipose Tissue/metabolism* ; Acupuncture Points