Hyperglycemia is a characteristic of diabetic nephropathy, inducing renal tubular cell apoptosis by eliciting oxidative stress and inflammation. Zinc (Zn) is known as an essential trace element in many enzymes and proteins involved in antioxidant defenses, electron transport, and exerting antiapoptotic or cytoprotective effects. In this study, the underlying mechanisms involved in the protective effects of Zn on high glucose-induced cytotoxicity were explored using cultured renal tubular epithelial cells (NRK-52E). The authors discovered that Zn supplementation inhibited high glucose (HG)-induced NRK-52E cell apoptosis by attenuating reactive oxygen species production, inhibiting HG-induced caspase-3 and caspase-9 activation, and inhibiting the release of cytochrome c from mitochondria to the cytosol. Further analysis revealed that Zn supplementation facilitated cell survival through increasing nuclear translocation of NF-E2-related factor 2 (Nrf2), leading to increased regulation of levels of two antioxidant enzymes, hemeoxygenase-1 and glutamate cysteine ligase, which provided an adaptive survival response against the HG-induced oxidative cytotoxicity. Moreover, the Zn-mediated increases in Nrf2 activity were suppressed by the pharmacological inhibition of Akt or extracellular signal-regulated kinase 1/2. Taken together, these findings suggest that Zn antiapoptosis capacity through the activation of Akt and ERK signal pathways leads to Nrf2 activation and, subsequently, Nrf2 target gene induction, thereby protecting the NRK-52E cells from HG-induced apoptosis.

Zinc (Zn) as an essential dietary element has been indicated in a number of protein functions in the prevention of numerous types of epithelial-to-mesenchymal transition (EMT)-driven fibrosis in vivo. However, relatively little is known regarding its effect in the EMT of the renal tubular epithelial cells, which play an important role in renal tubulointerstitial fibrosis and is an important component of the renal injury that is associated with diabetic nephropathy. The present study investigated the effect of Zn on the high glucose (HG)-induced EMT in a normal rat kidney tubular epithelial cell line (NRK-52E cells) and the underlying molecular mechanisms by immunofluorescence staining and western blot analysis. The present study identified that 10 µM of Zn supplementation prevented EMT changes, such as the loss of E-cadherin and the increase in α-smooth muscle actin and vimentin expression. Conversely, depletion of Zn with N,N,N',N'-tetrakis (2-pyridylmethyl)ethylenediamine in these cells aggravated changes in HG-induced EMT markers. Additionally, 10 µM Zn supplementation inhibited HG-induced transforming growth factor-β1 overexpression and reactive oxygen species production. Of note, HG increased phosphatidylinositol 3-kinase/Akt (PI3K/Akt) and mitogen-activated protein kinase (MAPK) pathways activation and Zn reversed HG-induced expression of PI3K/Akt, extracellular-signal-regulated kinase (ERK) and p38 MAPK, as well as EMT proteins. Finally, inhibitors of PI3K/Akt, ERK and p38 MAPK, and Zn supplementation blocked the HG-induced EMT in NRK-52E cells. These results indicate that physiologically optimal levels of Zn can inhibit HG-induced EMT of the NRK-52E cells possibly through several mechanisms, including abrogation of HG-induced oxidative stress, and PI3K/Akt, p38 MAPK and ERK activation in NRK-52E cells.

Abstract. Previous studies have demonstrated that zinc (Zn) is an essential trace element which is involved in male reproduction. The zinc transporter (ZnT) family, SLC30a, is involved in the maintenance of Zn homeostasis and in mediating intracellular signaling events; however, relatively little is known regarding the effect of ZnTs on testosterone synthesis. Thus, in the present study, we aimed to determine the effect of Zn transporter 7 (ZnT7) on testosterone synthesis in male CD-1 mice and mouse Leydig cells. The findings of the present study revealed that the concentrations of Zn in the testes and Leydig cells were significantly lower in mice fed a Zn-deficient diet compared with the control mice fed a Zn-adequate diet. In addition, ZnT7 was principally expressed and colocalized with steroidogenic acute regulatory protein (StAR) in the Leydig cells of male CD-1 mice. ZnT7 expression was downregulated in the mice fed a Zn-deficient diet, which led to decreases in the expression of the enzymes involved in testosterone synthesis namely cholesterol side-chain cleavage enzyme (P450scc) and 3β-hydroxysteroid dehydrogenase/D5-D4 isomerase (3β-HSD) as well as decreased serum testosterone levels. These results suggested that Znt7 may be involved in testosterone synthesis in the mouse testes. To examine this hypothesis, we used the mouse Leydig tumor cell line (MLTC-1 cell line) in which the ZnT7 gene had been silenced, in order to gauge the impact of changes in ZnT7 expression on testosterone secretion and the enzymes involved in testosterone synthesis. The results demonstrated that ZnT7 gene silencing downregulated the expression of StAR, P450scc and 3β-HSD as well as progesterone concentrations in the human chorionic gonadotrophin (hCG)-stimulated MLTC-1 cells. Taken together, these findings reveal that ZnT7 may play an important role in the regulation of testosterone synthesis by modulating steroidogenic enzymes, and may represent a therapeutic target in testosterone deficiency.

Vertical few-layer graphene (V-FLG) sheet is expected to be a high field emitter due to its electrical properties and open surface with sharp edges. However, the complicated and tedious preparation method using gaseous carbon-containing precursor limited the universal application of V-FLG. This paper reports a novel, simple, and green method to prepare vertical nitrogen-doped few-layer graphene (V-NFLG) on the metal surfaces that exhibit excellent field emission properties. The V-NFLG was grown on a Cu substrate using C60 as a precursor with the help of a nitrogen microwave plasma. Growth and doping mechanisms for the few-layer graphene are suggested based on microwave plasma emission spectra of C60/nitrogen. The as-prepared NFLG exhibits remarkable field emission performance, with a high field enhancement factor (7430 at the high field), a low turn-on field (1.45 V/μm at 10 μA/cm2), and high stability (within ±4%), showing its great potential for field emission applications.

RNA N6-methyladenosine (m6A) modification in tumorigenesis and progression has been highlighted and discovered in recent years. However, the molecular and clinical implications of m6A modification in melanoma tumor microenvironment (TME) and immune infiltration remain largely unknown. Here, we utilized consensus molecular clustering with nonnegative matrix factorization based on the melanoma transcriptomic profiles of 23 m6A regulators to determine the m6A modification clusters and m6A-related gene signature. Three distinct m6A modification patterns (m6A-C1, C2, and C3), which are characterized by specific m6A regulator expression, survival outcomes, and biological pathways, were identified in more than 1,000 melanoma samples. The immune profile analyses showed that these three m6A modification subtypes were highly consistent with the three known immune phenotypes: immune-desert (C1), immune-excluded (C2), and immune-inflamed (C3). Tumor digital cytometry (CIBERSORT, ssGSEA) algorithm revealed an upregulated infiltration of CD8+ T cell and NK cell in m6A-C3 subtype. An m6A scoring scheme calculated by principal component of m6A signatures stratified melanoma patients into high- and low-m6sig score subgroups; a high score was significantly associated with prolonged survival and enhanced immune infiltration. Furthermore, fewer somatic copy number alternations (SCNA) and PD-L1 expression were found in patients with high m6Sig score. In addition, patients with high m6Sig score demonstrated marked immune responses and durable clinical benefits in two independent immunotherapy cohorts. Overall, this study indicated that m6A modification is involved in melanoma tumor microenvironment immune regulation and contributes to formation of tumor immunogenicity. Comprehensive evaluation of the m6A modification pattern of individual tumors will provide more insights into molecular mechanisms of TME characterization and promote more effective personalized biotherapy strategies.