Effects of nuclear respiratory factor‑1 on apoptosis and mitochondrial dysfunction induced by cobalt chloride in H9C2 cells

Transcriptomic profiling analysis of the effect of palmitic acid on 3D spheroids of β-like cells derived from induced pluripotent stem cells

Type 2 diabetes (T2D) is posing a serious public health concern with a considerable impact on human life and health expenditures worldwide. The disease develops when insulin plasma level is insufficient for coping insulin resistance, caused by the decline of pancreatic β-cell function and mass. In β-cells, the lipotoxicity exerted by saturated free fatty acids in particular palmitate (PA), which is chronically elevated in T2D, plays a major role in β-cell dysfunction and mass. However, there is a lack of human relevant in vitro model to identify the underlying mechanism through which palmitate induces β-cell failure. In this frame, we have previously developed a cutting-edge 3D spheroid model of β-like cells derived from human induced pluripotent stem cells. In the present work, we investigated the signaling pathways modified by palmitate in β-like cells derived spheroids. When compared to the 2D monolayer cultures, the transcriptome analysis (FDR set at  0.1) revealed that the 3D spheroids upregulated the pancreatic markers (such as GCG, IAPP genes), lipids metabolism and transporters (CD36, HMGSC2 genes), glucose transporter (SLC2A6). Then, the 3D spheroids are exposed to PA 0.5 mM for 72 h. The differential analysis demonstrated that 32 transcription factors and 135 target genes were mainly modulated (FDR set at  0.1) including the upregulation of lipid and carbohydrates metabolism (HMGSC2, LDHA, GLUT3), fibrin metabolism (FGG, FGB), apoptosis (CASP7). The pathway analysis using the 135 selected targets extracted the fibrin related biological process and wound healing in 3D PA treated conditions. An overall pathway gene set enrichment analysis, performed on the overall gene set (with pathway significance cutoff at 0.2), highlighted that PA perturbs the citrate cycle, FOXO signaling and Hippo signaling as observed in human islets studies. Additional RT-PCR confirmed induction of inflammatory (IGFBP1, IGFBP3) and cell growth (CCND1, Ki67) pathways by PA. All these changes were associated with unaffected glucose-stimulated insulin secretion (GSIS), suggesting that they precede the defect of insulin secretion and death induced by PA. Overall, we believe that our data demonstrate the potential of our spheroid 3D islet-like cells to investigate the pancreatic-like response to diabetogenic environment.

Nuclear respiratory factor 1 promotes the progression of EBV-associated gastric cancer and maintains EBV latent infection

This study aimed to investigate the association of Epstein-Barr virus (EBV) with nuclear respiratory factor 1 (NRF1) and the biological function of NRF1 in EBV-associated gastric cancer (EBVaGC). Western blot and qRT-PCR were used to assess the effect of latent membrane protein 2A (LMP2A) on NRF1 expression after transfection with LMP2A plasmid or siLMP2A. The effects of NRF1 on the migration and apoptosis ability of GC cells were investigated by transwell assay and flow cytometry apoptosis analysis in vitro, respectively. In addition, we determined the regulatory role of NRF1 in EBV latent infection by western blot and droplet digital PCR (ddPCR). LMP2A upregulated NRF1 expression by activating the NF-κB pathway. Moreover, NRF1 upregulated the expression of N-Cadherin and ZEB1 to promote cell migration. NRF1 promoted the expression of Bcl-2 to increase the anti-apoptotic ability of cells. In addition, NRF1 maintained latent infection of EBV by promoting the expression of the latent protein Epstein-Barr nuclear antigen 1 (EBNA1) and inhibiting the expression of the lytic proteins. Our data indicated the role of NRF1 in EBVaGC progression and the maintenance of EBV latent infection. This provided a new theoretical basis for further NRF1-based anti-cancer therapy.

Promoting cardioprotection with fenugreek: Insights from CoCl2-induced hypoxia in neonatal rat cardiomyocytes

Objectives

This study aimed to investigate the protective effects of fenugreek on CoCl2-induced hypoxia in neonatal rat cardiomyocytes.

Materials and Methods

Primary cardiomyocytes were isolated from Sprague Dawley rats aged 0-2 days and incubated with various concentrations of fenugreek (10-320 µg/ml) and CoCl2-induced hypoxia for different durations (24, 48, and 72 hr). Cell viability, calcium signaling, beating rate, and gene expression were evaluated.

Results

Fenugreek treatments did not cause any toxicity in cardiomyocytes. At a concentration of 160 µg/ml for 24 hr, fenugreek protected the heart against CoCl2-induced hypoxia, as evidenced by reduced expression of caspases (-3, -6, -8, and -9) and other functional genes markers, such as HIF-1α, Bcl-2, IP3R, ERK5, and GLP-1r. Calcium signaling and beating rate were also improved in fenugreek-treated cardiomyocytes. In contrast, CoCl2 treatment resulted in up-regulation of the hypoxia gene HIF-1α and apoptotic caspases gene (-3, -9, -8, -12), and down-regulation of Bcl-2 activity.

Conclusion

Fenugreek treatment at a concentration of 160 µg/ml was not toxic to neonatal rat cardiomyocytes and protected against CoCl2-induced hypoxia. Furthermore, fenugreek improved calcium signaling and beating rate and altered gene expression. Fenugreek may be a potential therapeutic agent for promoting cardioprotection against hypoxia-induced injuries.

Studies on Regulation of Global Protein Profile and Cellular Bioenergetics of Differentiating SH-SY5Y Cells

The SH-SY5Y cells differentiated by sequential exposure of retinoic acid (RA) and brain-derived neurotrophic growth factor (BDNF) are a well-employed cellular model for studying the mechanistic aspects of neural development and neurodegeneration. Earlier studies from our lab have identified dramatic upregulation (77 miRNAs) and downregulation (17 miRNAs) of miRNAs in SH-SY5Y cells differentiated with successive exposure of RA + BDNF and demonstrated the essential role of increased levels of P53 proteins in coping with the differentiation-induced changes in protein levels. In continuation to our earlier studies, we have performed unbiased LC-MS/MS global protein profiling of naïve and differentiated SH-SY5Y cells and analyzed the identified proteins in reference to miRNAs identified in our earlier studies to identify the cellular events regulated by both identified miRNAs and proteins. Analysis of LC-MS/MS data has shown a significant increase and decrease in levels of 215 and 163 proteins, respectively, in differentiated SH-SY5Y cells. Integrative analysis of miRNA identified in our previous studies and protein identified in the present study is carried out to discover novel miRNA-protein regulatory modules to elucidate miRNA-protein regulatory relationships of differentiating neurons. In silico network analysis of miRNAs and proteins deregulated upon SH-SY5Y differentiation identified cell cycle, synapse formation, axonogenesis, differentiation, neuron projection, and neurotransmission, as the topmost involved pathways. Further, measuring mitochondrial dynamics and cellular bioenergetics using qPCR and Seahorse XFp Flux Analyzer, respectively, showed that differentiated cells possess increased mitochondrial dynamics and OCR relative to undifferentiated cells. In summary, our studies have identified a novel set of proteins deregulated during neuronal differentiation and establish the role of miRNAs identified in earlier studies in the regulation of proteins identified by LC-MS/MS-based global profiling of differentiating neurons, which will help in future studies related to neural development and neurodegeneration.

Nesfatin-1 protects H9c2 cardiomyocytes against cobalt chloride-induced hypoxic injury by modulating the MAPK and Notch1 signaling pathways

BACKGROUND

This study aimed to explore the effect of nesfatin-1 on cobalt chloride (CoCl₂)-induced hypoxic injury in cardiomyocyte H9c2 cells.

METHODS

H9c2 cardiomyocytes were induced by different concentrations of CoCl₂ to mimic the hypoxia condition. Cell viability was detected by MTT assay. Cell apoptosis was detected by TUNEL staining and flow cytometry. ROS production was detected using the fluorescence probe DCFH-DA. The mitochondrial membrane potential (MMP) was detected using the TMRE method. The levels of released lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT) were detected using the commercial kits. The protein levels of MAPK signaling members (p-JNK1/2, p-ERK1/2, and p-p38) and Notch1 signaling members (Notch1, Hes 1, and Jagged 1) were detected by Western blot.

RESULTS

CoCl₂ significantly promoted cell apoptosis, increased LDH leakage, MDA concentration, and decreased cell viability, SOD activity, GSH production, and CAT activity. CoCl₂-induced hypoxic injury in H9c2 cells was partially restored by nesfatin-1 treatment. Moreover, nesfatin-1 treatment attenuated CoCl₂-induced increase in ROS production and mitochondrial dysfunction, decreased mitochondrial membrane potential, Bax/Bcl-2 imbalance, as well as c-caspase-9 and c-caspase-3 levels. Moreover, nesfatin-1 treatment inhibited the activation of MAPK and Notch1 signaling pathways.

CONCLUSIONS

Nesfatin-1 could effectively protect H9c2 cells against CoCl₂-induced hypoxic injury by blocking MAPK and Notch1 signaling pathways, suggesting that nesfatin-1 might be a promising therapeutic agent for hypoxic cardiac injury.

Integrated On-Chip 3D Vascular Network Culture under Hypoxia

We developed a portable device made of poly(dimethylsiloxane) (PDMS)/polymethylmethacrylate (PMMA) for long-term 3D cell culture of vascular endothelial cells for the development of a vascular network and evaluated the device under different transitions between normoxia and hypoxia with good optical accessibility. The combination of a nested reservoir device and a bicarbonate/ascorbate buffer system accomplished on-chip incubation with 4.91 ± 0.86% pO₂ and 5.19 ± 1.70% pCO₂ for up to 10 days. Seventy-two hours of normoxic incubation preceding hypoxic culture increased the cell viability, network formation, and size and stability of the resulting lumens compared with those completely maintained in normoxia for the same total duration. We employed different parameters of the network (e.g., total mesh area, total length, number of branches, among others) for the comparison of different oxygen treatments in the device. The differential effect of hypoxic conditions based on the maturity of the vessels may be used as an external factor to improve vascular development in vitro.

Host Transcription Factors in Hepatitis B Virus RNA Synthesis

The hepatitis B virus (HBV) chronically infects over 250 million people worldwide and is one of the leading causes of liver cancer and hepatocellular carcinoma. HBV persistence is due in part to the highly stable HBV minichromosome or HBV covalently closed circular DNA (cccDNA) that resides in the nucleus. As HBV replication requires the help of host transcription factors to replicate, focusing on host protein–HBV genome interactions may reveal insights into new drug targets against cccDNA. The structural details on such complexes, however, remain poorly defined. In this review, the current literature regarding host transcription factors’ interactions with HBV cccDNA is discussed.

Identification of microRNA‑363‑3p as an essential regulator of chondrocyte apoptosis in osteoarthritis by targeting NRF1 through the p53‑signaling pathway

Osteoarthritis (OA) is a degenerative joint disease that affects the physical, and mental health of middle-aged and elderly people. The aims of the present study were to determine the biological function and molecular mechanisms of miR-363-3p in chondrocyte apoptosis. Exploration of the molecular mechanisms of OA may be helpful in the understand of the causes, and facilitating the prevention and treatment of OA. In the present study, the expression of nuclear respiratory factor1 (NRF1) was downregulated in the articular cartilage of OA rats in vivo and lipopolysaccharide (LPS)-treated chondrocytes in vitro. MicroRNAs (miRNA) are regulators of gene expression in the progression of OA. TargetScan software was used to predict that NRF1 was a potential target for miRNA (miR)-363, and this was confirmed in subsequent experiments. The expression of miR-363-3p was negatively correlated with the expression of NRF1, and its expression was significantly upregulated in OA model rats and in LPS-induced chondrocytes compared with the expression in the respective controls. In addition, the overexpression of miR-363-3p increased the levels of interleukin (IL)-1β, IL-6 and tumor necrosis factor-α in vivo, and was demonstrated to promote chondrocyte injury and apoptosis by Safranin O staining and TUNEL. Moreover, the inhibition of miR-363-3p expression increased the expression of NRF1 and protected chondrocytes from apoptosis in vitro and in vivo, whereas the overexpression of miR-363-3p downregulated NRF1 expression and promoted LPS-induced chondrocyte apoptosis through the p53 pathway in vitro. The results of this study suggested that miR-363-3p-mediated inhibition of NRF1may be associated with chondrocyte apoptosis in OA.