Metformin enhances METTL14-Mediated m6A methylation to alleviate NIT-1 cells apoptosis induced by hydrogen peroxide.

Injuries to pancreatic ß-cells are intricately linked to the onset of diabetes mellitus (DM). Metformin (Met), one of the most widely prescribed medications for diabetes and metabolic disorders, has been extensively studied for its antioxidant, anti-aging, anti-glycation, and hepatoprotective activities. N6-methyladenosine (m6A) plays a crucial role in the regulation of ß-cell growth and development, and its dysregulation is associated with metabolic disorders. This study aimed to elucidate the mechanistic basis of m6A involvement in the protective effects of Met against oxidative damage in pancreatic ß-cells. Hydrogen peroxide (H2O2) was employed to induce ß-cell damage. Remarkably, Met treatment effectively increased methylation levels and the expression of the methyltransferase METTL14, subsequently reducing H2O2-induced apoptosis. Knocking down METTL14 expression using siRNA significantly compromised cell viability. Conversely, targeted overexpression of METTL14 specifically in ß-cells substantially enhanced their capacity to withstand H2O2-induced stress. Molecular evidence suggests that the anti-apoptotic properties of Met may be mediated through Bcl-xL and Bim proteins. In conclusion, our findings indicate that Met induces METTL14-mediated alterations in m6A methylation levels, thereby shielding ß-cells from apoptosis and oxidative damage induced by oxidative stress.

Increased serum extrachromosomal circular DNA SORBS1circle level is associated with insulin resistance in patients with newly diagnosed type 2 diabetes mellitus.

BACKGROUND: Extrachromosomal circular DNAs (eccDNAs) exist in human blood and somatic cells, and are essential for oncogene plasticity and drug resistance. However, the presence and impact of eccDNAs in type 2 diabetes mellitus (T2DM) remains inadequately understood. METHODS: We purified and sequenced the serum eccDNAs obtained from newly diagnosed T2DM patients and normal control (NC) subjects using Circle-sequencing. We validated the level of a novel circulating eccDNA named sorbin and SH3-domain- containing-1circle97206791-97208025 (SORBS1circle) in 106 newly diagnosed T2DM patients. The relationship between eccDNA SORBS1circle and clinical data was analyzed. Furthermore, we explored the source and expression level of eccDNA SORBS1circle in the high glucose and palmitate (HG/PA)-induced hepatocyte (HepG2 cell) insulin resistance model. RESULTS: A total of 22,543 and 19,195 eccDNAs were found in serum samples obtained from newly diagnosed T2DM patients and NC subjects, respectively. The T2DM patients had a greater distribution of eccDNA on chromosomes 1, 14, 16, 17, 18, 19, 20 and X. Additionally, 598 serum eccDNAs were found to be upregulated, while 856 eccDNAs were downregulated in T2DM patients compared with NC subjects. KEGG analysis demonstrated that the genes carried by eccDNAs were mainly associated with insulin resistance. Moreover, it was validated that the eccDNA SORBS1circle was significantly increased in serum of newly diagnosed T2DM patients (106 T2DM patients vs. 40 NC subjects). The serum eccDNA SORBS1circle content was positively correlated with the levels of glycosylated hemoglobin A1C (HbA1C) and homeostasis model assessment of insulin resistance (HOMA-IR) in T2DM patients. Intracellular eccDNA SORBS1circle expression was significantly enhanced in the high glucose and palmitate (HG/PA)-induced hepatocyte (HepG2 cell) insulin resistance model. Moreover, the upregulation of eccDNA SORBS1circle in the HG/PA-treated HepG2 cells was dependent on generation of apoptotic DNA fragmentation. CONCLUSIONS: These results provide a preliminary understanding of the circulating eccDNA patterns at the early stage of T2DM and suggest that eccDNA SORBS1circle may be involved in the development of insulin resistance.

LncRNA HEM2ATM improves obesity-associated adipose tissues meta-inflammation and insulin resistance by interacting with heterogeneous nuclear ribonucleoprotein U.

Obesity is a complicated metabolic disease characterized by meta-inflammation in adipose tissues. In this study, we explored the roles of a new long non-coding RNA (lncRNA), HEM2ATM, which is highly expressed in adipose tissue M2 macrophages, in modulating obesity-associated meta-inflammation and insulin resistance. HEM2ATM expression decreased significantly in adipose tissue macrophages (ATMs) obtained from epididymal adipose tissues of high-fat diet (HFD)-induced obese mice. Overexpression of macrophage HEM2ATM improved meta-inflammation and insulin resistance in the adipose tissues of HFD-fed mice. Functionally, HEM2ATM negatively regulated the production of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in macrophages. Mechanistically, HEM2ATM bound to heterogeneous nuclear ribonucleoprotein U (hnRNP U), suppressed hnRNP U translocation from the nucleus to the cytoplasm, hindered the function of cytoplasmic hnRNP U on TNF-α and IL-6 mRNA stabilization, and decreased the secretion of TNF-α and IL-6. Collectively, HEM2ATM is a novel suppressor of obesity-associated meta-inflammation and insulin resistance.

Decreased Urine N6-methyladenosine level is closely associated with the presence of diabetic nephropathy in type 2 diabetes mellitus.

Background: To investigate the dynamic changes of urine N6-methyladenosine (m6A) levels in patients with type 2 diabetes mellitus (T2DM) and diabetic nephropathy (DN) and evaluate the clinical significance. Methods: First, the levels of urine m6A were examined and compared among 62 patients with T2DM, 70 patients with DN, and 52 age- and gender-matched normal glucose tolerant subjects (NGT) by using a MethyIFIashTM Urine m6A Quantification Kit. Subsequently, we compared the concentrations of urine m6A between different stages of DN. Moreover, statistical analysis was performed to evaluate the association of urine m6A with DN. Results: The levels of m6A were significantly decreased in patients with DN [(16.10 ± 6.48) ng/ml], compared with NGT [(23.12 ± 7.52) ng/ml, P < 0.0001] and patients with T2DM [(20.39 ± 7.16) ng/ml, P < 0.0001]. Moreover, the concentrations of urine m6A were obviously reduced with the deterioration of DN. Pearson rank correlation and regression analyses revealed that m6A was significantly associated with DN (P < 0.05). The areas under the receiver operator characteristics curve (AUC) were 0.783 (95% CI, 0.699 - 0.867, P < 0.0001) for the DN and NGT groups, and 0.737 (95% CI, 0.639 - 0.835, P < 0.0001) for the macroalbuminuria and normoalbuminuria groups, and the optimal cutoff value for m6A to distinguish the DN from NGT and the macroalbuminuria from normoalbuminuria cases was 0.4687 (diagnostic sensitivity, 71%; diagnostic specificity, 76%) and 0.4494 (diagnostic sensitivity, 79%; diagnostic specificity, 66%), respectively. Conclusions: The levels of urine m6A are significantly decreased in patients with DN and change with the deterioration of DN, which could serve as a prospective biomarker for the diagnosis of DN.

The m6A Methyltransferase METTL3 Ameliorates Methylglyoxal-Induced Impairment of Insulin Secretion in Pancreatic ß Cells by Regulating MafA Expression.

Methylglyoxal, a major precursor of advanced glycation end products, is elevated in the plasma of patients with type 2 diabetes mellitus. Islet ß-cell function was recently shown to be regulated by N6-methyladenosine (m6A), an RNA modification consisting of methylation at the N6 position of adenosine. However, the role of m6A methylation modification in methylglyoxal-induced impairment of insulin secretion in pancreatic ß cells has not been clarified. In this study, we showed that treatment of two ß-cell lines, NIT-1 and ß-TC-6, with methylglyoxal reduced m6A RNA content and methyltransferase-like 3 (METTL3) expression levels. We also showed that silencing of METTL3 inhibited glucose-stimulated insulin secretion (GSIS) from NIT-1 cells, whereas upregulation of METTL3 significantly reversed the methylglyoxal-induced decrease in GSIS. The methylglyoxal-induced decreases in m6A RNA levels and METTL3 expression were not altered by knockdown of the receptor for the advanced glycation end product but were further decreased by silencing of glyoxalase 1. Mechanistic investigations revealed that silencing of METTL3 reduced m6A levels, mRNA stability, and the mRNA and protein expression levels of musculoaponeurotic fibrosarcoma oncogene family A (MafA). Overexpression of MafA greatly improved the decrease in GSIS induced by METTL3 silencing; silencing of MafA blocked the reversal of the MG-induced decrease in GSIS caused by METTL3 overexpression. The current study demonstrated that METTL3 ameliorates MG-induced impairment of insulin secretion in pancreatic ß cells by regulating MafA.

A SGLT2 Inhibitor Dapagliflozin Alleviates Diabetic Cardiomyopathy by Suppressing High Glucose-Induced Oxidative Stress in vivo and in vitro.

Diabetic cardiomyopathy (DCM) is a serious complication of diabetes mellitus (DM). One of the hallmarks of the DCM is enhanced oxidative stress in myocardium. The aim of this study was to research the underlying mechanisms involved in the effects of dapagliflozin (Dap) on myocardial oxidative stress both in streptozotocin-induced DCM rats and rat embryonic cardiac myoblasts H9C2 cells exposed to high glucose (33.0 mM). In in vivo studies, diabetic rats were given Dap (1 mg/ kg/ day) by gavage for eight weeks. Dap treatment obviously ameliorated cardiac dysfunction, and improved myocardial fibrosis, apoptosis and oxidase stress. In in vitro studies, Dap also attenuated the enhanced levels of reactive oxygen species and cell death in H9C2 cells incubated with high glucose. Mechanically, Dap administration remarkably reduced the expression of membrane-bound nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits gp91phox and p22phox, suppressed the p67phox subunit translocation to membrane, and decreased the compensatory elevated copper, zinc superoxide dismutase (Cu/Zn-SOD) protein expression and total SOD activity both in vivo and in vitro. Collectively, our results indicated that Dap protects cardiac myocytes from damage caused by hyperglycemia through suppressing NADPH oxidase-mediated oxidative stress.

Serum platelet factor 4 is a reliable activity parameter in adult patients with inflammatory bowel disease: A pilot study.

To investigate the diagnostic utility of serum platelet factor 4 (PF4) levels and to assess its accuracy in detecting inflammatory bowel disease activity.This study included 45 patients with ulcerative colitis (UC), 45 patients with Crohn disease (CD), and 30 control subjects at Jinling Hospital between May 2014 and July 2015. Laboratory tests measured white blood count, C-reactive protein, erythrocyte sedimentation rate, and platelet count. PF4 was examined by enzyme-linked immunosorbent assays. Patients were divided into 2 groups according to disease activity: active and inactive.Median PF4 values dramatically increased in UC and CD patients compared with the healthy group (UC: 26.64 [20.00-36.22] mg/mL vs 20.02 [14.63-26.83] mg/mL, P = 0.002; CD: 25.56 [18.57-36.36] mg/mL vs 20.02 [14.63-26.83] mg/mL, P = 0.014); however, the serum PF4 levels between UC and CD failed to show a significant difference (26.64 [20.00-36.22] mg/mL vs 25.56 [18.57-36.36] mg/mL, P = 0.521). Furthermore, serum PF4 levels were elevated in both UC and CD patients with active disease (UC: 20.19 [14.89-23.53] mg/mL vs 28.86 [22.57-37.29] mg/mL, P < 0.001; CD: 18.33 [16.72-25.77] mg/mL vs 34.38 [22.58-39.92] mg/mL, P < 0.001). Multivariate analysis revealed higher PF4 level as an independent predictor of disease activity in UC and CD patients (UC: odds ratio 30.375, P = 0.002; CD: odds ratio 54.167, P < 0.001). The cut-off level of PF4 for distinguishing active from inactive UC patients was 24.1 mg/mL. While in CD patients, the cut-off level of PF4 was 19.24 mg/mL.Serum PF4 levels could be a potential biomarker for monitoring the disease activity of inflammatory bowel disease.

[Serum non-esterified fatty acids to albumin ratio increased significantly in children with nephrotic syndrome].

OBJECTIVE: To analyze serum levels of non-esterified fatty acids (NEFA) and albumin (ALB) in children with nephrotic syndrome (NS) and investigate the clinical significance of altered serum NEFA to ALB ratio in children with NS in acute and remission phases. METHODS: Serum levels of NEFA and ALB were measured in 55 NS children in acute phase, in 33 NS children in remission and in 122 healthy control children, and the ratio of NEFA to ALB was calculated. The other lipid/lipoprotein and renal function parameters were also analyzed in these children. RESULTS: Compared with the healthy control children, children with NS had a significantly decreased serum ALB level (t=11.152, P<0.001) and a significantly increased NEFA to ALB ratio (t=4.991, P<0.001). Compared with NS children in remission, those in acute phase showed a significantly decreased ALB (Z=7.822, P<0.001) and an increased NEFA to ALB ratio (t=4.991, P<0.001). In all the NS children, NEFA to ALB ratio was positively correlated with the levels of TC (r=0.564, P<0.001), TG (r=0.444, P<0.001), LDL-C (r=0.625, P<0.001), urea (r=0.437, P<0.001), creatinine (r=0.278, P=0.013), and uric acid (r=0.397, P<0.001), while negatively correlated with the level of total protein (r=-0.461, P<0.001). Multiple linear regression analyses showed that NEFA to ALB ratio was independently associated with serum urea levels (ß=0.703, P=0.001; adjusted R2=0.494) after adjustment of other related factors. CONCLUSION: Serum NEFA to ALB ratio is significantly increased in NS children in close association with impaired kidney function, and may function as a novel parameter for assessing the development of NS.