Downregulation of Sirt3 contributes to ß-cell dedifferentiation via FoxO1 in type 2 diabetic mellitus.

AIMS: FoxO1 is an important factor in the ß-cell differentiation in type 2 diabetes mellitus (T2DM). Sirt3 is found to be involved in FoxO1 function. This study investigated the role of Sirt3 in the ß-cell dedifferentiation and its mechanism. METHODS: Twelve-week-old db/db mice and INS1 cells transfected with Sirt3-specific short hairpin RNA (shSirt3) were used to evaluate the dedifferentiation of ß-cell. Insulin levels were measured by enzyme linked immunosorbent assay. The proteins of Sirt3, T-FoxO1, Ac-FoxO1 and differentiation indexes such as NGN3, OCT4, MAFA were determined by western blot or immunofluorescence staining. The combination of Sirt3 and FoxO1 was determined by the co-immunoprecipitation assay. The transcriptional activity of FoxO1 was detected by dual luciferase reporter assay. RESULTS: Both the in vivo and in vitro results showed that Sirt3 was decreased along with ß-cell dedifferentiation and decreased function of insulin secretion under high glucose conditions. When Sirt3 was knocked down in INS1 cells, increased ß-cell dedifferentiation and lowered insulin secretion were observed. This effect was closely related to the amount loss and the decreased deacetylation of FoxO1, which resulted in a reduction in transcriptional activity. CONCLUSION: Downregulation of Sirt3 contributes to ß-cell dedifferentiation in high glucose via FoxO1. Intervention of Sirt3 may be an effective approach to prevent ß-cell failure in T2DM.

Decreased Sirt3 contributes to cyclic production of reactive oxygen species and islet ß-cell apoptosis in high glucose conditions.

BACKGROUND: Reactive oxygen species (ROS) plays a vital role in the apoptosis of islet ß-cells in type 2 diabetes mellitus (T2DM). Sirt3 (Sirtuin 3, a deacetylase) and FoxO1 (a transcription factor) might be involved in ROS production. This study was to investigate mechanism of ROS production and ß-cell apoptosis in T2DM. METHODS: Oxidative stress and apoptosis in islets of db/db mice and high glucose cultured ß-cells were observed by terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay and western blotting. Then, H2O2 was used to ascertain the effect of ROS on the expression of Sirt3. Meanwhile, FoxO1, antioxidant enzymes - catalase (CAT) and manganese superoxide dismutase (MnSOD) and ß-cell apoptosis were also determined by western blotting. Finally, Sirt3 was knocked down to evaluate the effect on oxidative stress and apoptosis of ß-cells. RESULTS: Under high glucose environment, enhanced ROS made a decrease of Sirt3 expression, which increased acetylation of FoxO1, thus reduced the expression of its target proteins -MnSOD and CAT, and further significantly increased ROS levels. Increased ROS finally led to the apoptosis of ß-cells. CONCLUSION: Down-regulation of Sirt3 plays an important role in the cyclic production of ROS and ß-cell apoptosis. Targeting Sirt3 may be favorable for the treatment of T2DM.

A new ferroptosis-related genetic mutation risk model predicts the prognosis of skin cutaneous melanoma.

Background: Ferroptosis is an iron-dependent cell death mode and closely linked to various cancers, including skin cutaneous melanoma (SKCM). Although attempts have been made to construct ferroptosis-related gene (FRG) signatures for predicting the prognosis of SKCM, the prognostic impact of ferroptosis-related genetic mutations in SKCM remains lacking. This study aims to develop a prediction model to explain the relationship between ferroptosis-related genetic mutations and clinical outcomes of SKCM patients and to explore the potential value of ferroptosis in SKCM treatment. Methods: FRGs which significantly correlated with the prognosis of SKCM were firstly screened based on their single-nucleotide variant (SNV) status by univariate Cox regression analysis. Subsequently, the least absolute shrinkage and selection operator (LASSO) and Cox regressions were performed to construct a new ferroptosis-related genetic mutation risk (FerrGR) model for predicting the prognosis of SKCM. We then illustrate the survival and receiver operating characteristic (ROC) curves to evaluate the predictive power of the FerrGR model. Moreover, independent prognostic factors, genomic and clinical characteristics, immunotherapy, immune infiltration, and sensitive drugs were compared between high-and low-FerrGR groups. Results: The FerrGR model was developed with a good performance on survival and ROC analysis. It was a robust independent prognostic indicator and followed a nomogram constructed to predict prognostic outcomes for SKCM patients. Besides, FerrGR combined with tumor mutational burden (TMB) or MSI (microsatellite instability) was considered as a combined biomarker for immunotherapy response. The high FerrGR group patients were associated with an inhibitory immune microenvironment. Furthermore, potential drugs target to high FerrGR samples were predicted. Conclusion: The FerrGR model is valuable to predict prognosis and immunotherapy in SKCM patients. It offers a novel therapeutic option for SKCM.

Quercetin protects islet ß-cells from oxidation-induced apoptosis via Sirt3 in T2DM.

OBJECTIVES: Sirt3 may regulate ROS production and might be involved in ß-cell apoptosis, which plays an important role in the progression of type 2 diabetes mellitus (T2DM). Quercetin is a potent anti-oxidative bioflavonoid, but its effects on T2DM remain to be explored. This study aimed to investigate the effects of quercetin on ß-cell apoptosis and explore its mechanisms. MATERIALS AND METHODS: The effects of quercetin were conducted on db/db mice and INS1 cells. Fasting blood glucose was determined by the colorimetric method, serum insulin was measured by enzyme-linked immunosorbent assay (ELISA). Meanwhile, Sirt3 in INS1 cells was knocked down by plasmid transfection. The antioxidant proteins (SOD2 and CAT), apoptosis proteins (cleaved Caspase-3, Bax, and BCL-2), and Sirt3 protein in pancreases and INS1 cells were determined by western blotting. RESULTS: When INS1 cells and diabetic mice were treated with quercetin, the levels of SOD2, CAT, and Sirt3 proteins were increased, the levels of cleaved Caspase-3 and the ratio of Bax to BCL-2 were decreased at different degrees, along with reduced blood glucose levels and elevated insulin levels in diabetic mice. When Sirt3 was knocked down in INS1 cells, increase of two antioxidants and decrease of cell apoptosis generated by quercetin could not occur. CONCLUSION: Quercetin protected islet ß-cells from oxidation-induced apoptosis via Sirt3 in T2DM, which would be beneficial to develop new strategies for preventing ß-cell failure in T2DM.

Rapid immunoassay and clinical evaluation of the SARS-CoV-2 antibody assay on the real express-6 analyzer.

We developed a rapid and simple magnetic chemiluminescence enzyme immunoassay on the Real Express-6 analyzer, which could simultaneously detect immunoglobulin G and immunoglobulin M antibodies against SARS-CoV-2 virus in human blood within 18 min, and which could be used to detect clinical studies to verify its clinical efficacy. We selected blood samples from 185 COVID-19 patients confirmed by polymerase chain reaction and 271 negative patients to determine the clinical detection sensitivity, specificity, stability, and precision of this method. Meanwhile, we also surveyed the dynamic variance of viral antibodies during SARS-CoV-2 infection. This rapid immunoassay test has huge potential benefits for rapid screening of SARS-CoV-2 infection and may help clinical drug and vaccine development.

Tetrahydrobiopterin contributes to the proliferation of mesangial cells and accumulation of extracellular matrix in early-stage diabetic nephropathy.

OBJECTIVES: Nitric oxide (NO) plays an important role in the progression of early-stage diabetic nephropathy (DN), which is found to contribute to extracellular matrix (ECM) accumulation in mesangial cells (MCs). As a cofactor for NO production, tetrahydrobiopterin (BH4 ), a folacin analogue, may be responsible for the ECM accumulation and proliferation of MCs. This study was to investigate the effects of BH4 on glomerulosclerosis in early-stage DN. METHODS: In in vitro studies with cultured mesangial cells and in vivo studies with streptozotocin-induced diabetic rats, BH4 levels were assayed by HPLC; NO was determined by Griess agents; laminin and collagen IV were determined by enzyme-linked immunosorbent assay; the inducible NO synthase protein was determined by immunofluorescence staining and Western blot; and mesangial matrix expansion and MC proliferation in the renal cortex were observed by periodic acid-schiff staining and transmission electron microscopy, respectively. KEY FINDINGS: The in vivo and in vitro studies indicated that the increased BH4 resulted in the overproduction of NO, ECM accumulation and the proliferation of MCs in early-stage DN. CONCLUSIONS: Our results suggest that inhibiting excessive BH4 may be a potential approach to prevent glomerulosclerosis in early-stage DN.