Hypoxia Augments Increased HIF-1α and Reduced Survival Protein p-Akt in Gelsolin (GSN)-Dependent Cardiomyoblast Cell Apoptosis

Effects of NRF-1 and PGC-1α cooperation on HIF-1α and rat cardiomyocyte apoptosis under hypoxia

BACKGROUND

Hypoxia is a primary inducer of cardiomyocyte injury, its significant marker being hypoxia-induced cardiomyocyte apoptosis. Nuclear respiratory factor-1 (NRF-1) and hypoxia-inducible factor-1α (HIF-1α) are transcriptional regulatory elements implicated in multiple biological functions, including oxidative stress response. However, their roles in hypoxia-induced cardiomyocyte apoptosis remain unknown. The effect HIF-1α, together with NRF-1, exerts on cardiomyocyte apoptosis also remains unclear.

METHODS

We established a myocardial hypoxia model and investigated the effects of these proteins on the proliferation and apoptosis of rat cardiomyocytes (H9C2) under hypoxia. Further, we examined the association between NRF-1 and HIF-1α to improve the current understanding of NRF-1 anti-apoptotic mechanisms.

RESULTS

The results show that NRF-1 and HIF-1α are important anti-apoptotic molecules in H9C2 cells under hypoxia, although their regulatory mechanisms differ. NRF-1 could bind to the promoter region of Hif1a and negatively regulate its expression. Additionally, HIF-1β exhibited competitive binding with NRF-1 and HIF-1α, demonstrating a synergism between NRF-1 and the peroxisome proliferator-activated receptor-gamma coactivator-1α.

CONCLUSION

These results indicate that cardiomyocytes can regulate different molecular patterns to tolerate hypoxia, providing a novel methodological framework for studying cardiomyocyte apoptosis under hypoxia.

Deletions in GSN gene associated with growth traits of four Chinese cattle breeds

The aim of this study was to assess the potential of 21 bp mutation in the second intron of the GSN gene as a molecular marker-assisted by exploring the effect of 21 bp mutation on growth traits in four beef cattle breeds. Gelsolin (GSN), a member of the superfamily of gel proteins, is involved in the regulation of a variety of cellular activities in the organism and plays an important function in cell motility, apoptosis, signal transduction and inflammatory responses. Gelatin can not only negatively regulate the pro-apoptotic effect of P53 protein, but also promote apoptosis by blocking the interaction between actin and deoxyribonuclease, so, the GSN gene was selected as a candidate gene in this study. In this study, a 21 bp mutation on the second intron to the GSN gene was verified in 573 individuals of Yunling (YL, n = 220), Jiaxian (JX, n = 140), Xianan (XN, n = 114) and Qinchuan (QC, n = 97) cattle breeds using Once PCR and agarose gel electrophoresis. The association analysis of polymorphisms in the GSN gene with growth traits in four breeds was revealed: in YL cattle, the heart girth and forehead size of heterozygous ID genotype were significantly higher than II genotype (P < 0.05). In JX cattle, the withers height, body length and heart girth of II and ID genotype were significantly highest than DD genotype (P < 0.01); the height at hip cross and height at sacrum of II genotype was significantly highest than DD genotype (P < 0.01), but ID genotype was significantly higher than DD genotype. In XN cattle, the abdominal girth and circumference of the cannon bone of II genotype were significantly higher than ID genotype (P < 0.05). In QC cattle, the hucklebone width of ID genotype was significantly the highest than II genotype (P < 0.01). The results suggest that GSN may be an important candidate gene and that a 21 bp mutation on the second intron to the GSN gene can be used for molecular marker-assisted selection of four beef cattle breeds.

Identification of aberrantly methylated differentially expressed genes targeted by differentially expressed miRNA in osteosarcoma

Background

Osteosarcoma (OS) is the most common primary bone tumors diagnosed in children and adolescents. Recent studies have shown a prognostic role of DNA methylation in various cancers, including OS. The aim of this study was to identify the aberrantly methylated genes that are prognostically relevant in OS.

Methods

The differentially expressed mRNAs, miRNAs and methylated genes (DEGs, DEMs and DMGs respectively) were screened from various GEO databases, and the potential target genes of the DEMs were predicted by the RNA22 program. The protein-protein interaction (PPI) networks were constructed using the STRING database and visualized by Cytoscape software. The functional enrichment and survival analyses of the screened genes was performed using the R software.

Results

Forty-seven downregulated hypermethylated genes and three upregulated hypomethylated genes were identified that were enriched in cell activation, migration and proliferation functions, and were involved in cancer-related pathways like JAK-STAT and PI3K-AKT. Eight downregulated hypermethylated tumor suppressor genes (TSGs) were identified among the screened genes based on the TSGene database. These hub genes are likely involved in OS genesis, progression and metastasis, and are potential prognostic biomarkers and therapeutic targets.

Conclusions

TSGs including PYCARD, STAT5A, CXCL12 and CXCL14 were aberrantly methylated in OS, and are potential prognostic biomarkers and therapeutic targets. Our findings provide new insights into the role of methylation in OS progression.

Cross talk between 26S proteasome and mitochondria in human mesenchymal stem cells' ability to survive under hypoxia stress

Mesenchymal stem cells (MSCs) are regarded as unique cells which play an imperative role in the field of regenerative medicine. They are characterized by the self-renewal capacity, multi-lineage differentiation abilities and immunomodulation properties which render them perfectly ideal cell type for treating a wide range of chronic diseases. Despite these enchanted features, there are many hurdles that need to be circumvented to ensure their long-term survival and viability after transplantation. Recently, hypoxia has been indicated as one of the most baffling stress conditions that can affect the survival rate of MSCs either positively or negatively depending on the level of hypoxia. MSCs can survive well under moderate hypoxia, but die shortly if they were exposed to severe hypoxia without clearly convincing explanation for this enigma. The current study reveals a novel mechanism of 26S proteasome in controlling the ability of BM-MSCs to withstand hypoxic stress by maintaining proper mitochondrial function. The results indicated that 26S proteasome remains functioning once BM- MSCs are exposed to moderate hypoxia (2.5%O2) and preserves their survival and proliferation mediated by intact mitochondrial performance, whereas 26S proteasome becomes inactive when BM-MSCs faces severe hypoxia that lead to poor mitochondrial function and less chance to survive longer. The outcomes of this study demonstrated the importance of 26S proteasome machinery in enhancing the resistance of BM-MSCs to hypoxic stress condition which may help in better planning future studies that target this system. Schematic representation summarizing the findings of the current study. 26S proteasome function preservation in normoxia and moderate hypoxia leads to maintain appropriate proliferation and mitochondrial activity in human BM-MSCs and promote their survival. On the opposite side, severe hypoxia disrupts the 26S proteasome function leading to significant reduction in the proliferation, survival and mitochondrial dynamics in human BM-MSCs causing their death.

Functional characterization of alternatively spliced GSN in head and neck squamous cell carcinoma

We have recently performed the characterization of alternative splicing events (ASEs) in head and neck squamous cell carcinoma, which allows dysregulation of protein expression common for cancer cells. Such analysis demonstrated a high ASE prevalence among tumor samples, including tumor-specific alternative splicing in the GSN gene.In vitro studies confirmed that overall expression of either ASE-GSN or wild-type GSN (WT-GSN) isoform inversely correlated with cell proliferation, whereas the high ratio of ASE-GSN to WT-GSN correlated with increased cellular invasion. Additionally, a change in expression of either isoform caused compensatory changes in expression of the other isoform. Our results suggest that the overall expression and the balance between GSN isoforms are mediating factors in proliferation, while increased overall expression of ASE-GSN is specific to cancer tissues. As a result, we propose ASE-GSN can serve not only as a biomarker of disease and disease progression, but also as a neoantigen for head and neck squamous cell carcinoma treatment, for which only a limited number of disease-specific targeted therapies currently exist.

Quantitative Proteomic Analysis of 2D and 3D Cultured Colorectal Cancer Cells: Profiling of Tankyrase Inhibitor XAV939-Induced Proteome

Recently there has been a growing interest in three-dimensional (3D) cell culture systems for drug discovery and development. These 3D culture systems better represent the in vivo cellular environment compared to two-dimensional (2D) cell culture, thereby providing more physiologically reliable information on drug screening and testing. Here we present the quantitative profiling of a drug-induced proteome in 2D- and 3D-cultured colorectal cancer SW480 cells using 2D nanoflow liquid chromatography-tandem mass spectrometry (2D-nLC-MS/MS) integrated with isobaric tags for relative and absolute quantitation (iTRAQ). We identified a total of 4854 shared proteins between 2D- and 3D-cultured SW480 cells and 136/247 differentially expressed proteins (up/down-regulated in 3D compared to 2D). These up/down-regulated proteins were mainly involved in energy metabolism, cell growth, and cell-cell interactions. We also investigated the XAV939 (tankyrase inhibitor)-induced proteome to reveal factors involved in the 3D culture-selective growth inhibitory effect of XAV939 on SW480 cells. We identified novel XAV939-induced proteins, including gelsolin (a possible tumor suppressor) and lactate dehydrogenase A (a key enzyme of glycolysis), which were differentially expressed between 2D- and 3D-cultured SW480 cells. These results provide a promising informative protein dataset to determine the effect of XAV939 on the expression levels of proteins involved in SW480 cell growth.

Estrogen and/or Estrogen Receptor α Inhibits BNIP3-Induced Apoptosis and Autophagy in H9c2 Cardiomyoblast Cells

The process of autophagy in heart cells maintains homeostasis during cellular stress such as hypoxia by removing aggregated proteins and damaged organelles and thereby protects the heart during the times of starvation and ischemia. However, autophagy can lead to substantial cell death under certain circumstances. BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3), a hypoxia-induced marker, has been shown to induce both autophagy and apoptosis. A BNIP3-docked organelle, e.g., mitochondria, also determines whether autophagy or apoptosis will take place. Estrogen (E2) and estrogen receptor (ER) alpha (ERα) have been shown to protect the heart against mitochondria-dependent apoptosis. The aim of the present study is to investigate the mechanisms by which ERα regulates BNIP3-induced apoptosis and autophagy, which is associated with hypoxic injury, in cardiomyoblast cells. An in vitro model to mimic hypoxic injury in the heart by engineering H9c2 cardiomyoblast cells to overexpress BNIP3 was established. Further, the effects of E2 and ERα in BNIP3-induced apoptosis and autophagy were determined in BNIP3 expressing H9c2 cells. Results from TUNEL assay and Immunoflourecense assay for LC3 puncta formation, respectively, revealed that ERα/E2 suppresses BNIP3-induced apoptosis and autophagy. The Western blot analysis showed ERα/E2 decreases the protein levels of caspase 3 (apoptotic marker), Atg5, and LC3-II (autophagic markers). Co-immunoprecipitation of BNIP3 and immunoblotting of Bcl-2 and Rheb showed that ERα reduced the interaction between BNIP3 and Bcl-2 or Rheb. The results confirm that ERα binds to BNIP3 causing a reduction in the levels of functional BNIP3 and thereby inhibits cellular apoptosis and autophagy. In addition, ERα attenuated the activity of the BNIP3 promoter by binding to SP-1 or NFκB sites.

Oolong tea prevents cardiomyocyte loss against hypoxia by attenuating p-JNK mediated hypertrophy and enhancing P-IGF1R, p-akt, and p-Badser136 activity and by fortifying NRF2 antioxidation system

Tea, the most widely consumed natural beverage has been associated with reduced mortality risk from cardiovascular disease. Oolong tea is a partially fermented tea containing high levels of catechins, their degree of oxidation varies between 20%-80% causing differences in their active metabolites. In this study we examined the effect of oolong tea extract (OTE) obtained by oxidation at low-temperature for short-time against hypoxic injury and found that oolong tea provides cyto-protective effects by suppressing the JNK mediated hypertrophic effects and by enhancing the innate antioxidant mechanisms in neonatal cardiomyocytes and in H9c2 cells. OTE effectively attenuates 24 h hypoxia-triggered cardiomyocyte loss by suppressing caspase-3-cleavage and apoptosis in a dose-dependent manner. OTE also enhances the IGFIR/p-Akt associated survival-mechanism involving the elevation of p-Bad^ser136 in a dose-dependent manner to aid cellular adaptations against hypoxic challenge. The results show the effects and mechanism of Oolong tea to provide cardio-protective benefits during hypoxic conditions.

MicroRNA-30c-5p ameliorates hypoxia-reoxygenation-induced tubular epithelial cell injury via HIF1α stabilization by targeting SOCS3

The cellular hypoxia-reoxygenation (H/R) model is an ideal method to study ischemia-reperfusion injury, which is associated with high mortality. The role of microRNA-30c-5p (miR-30c-5p) in the H/R epithelial cell model remains unknown. In the current study, we observed a significant reduction in apoptosis when miR-30c-5p was up-regulated. We also found decreased levels of C-caspase-3 (C-CASP3) and Bcl-2-associated X (BAX) proteins and increased levels of B-cell lymphoma-2 (BCL2). Epidermal growth factor receptor (EGFR) showed similar results. Down-regulating miR-30c-5p increased the levels of apoptosis and C-CASP3 and BAX expression; additionally, cell proliferation was inhibited. Hypoxia-inducible factor 1α (HIF1α) protein expression levels were up-regulated in response to up-regulation of miR-30c-5p expression. The anti-apoptotic and proliferative effects of miR-30c-5p decreased significantly after the HIF1α protein levels were knocked down. Using a luciferase reporter assay, we confirmed that miR-30c-5p targets suppressor of cytokine signaling-3 (SOCS3). HIF1α levels increased when SOCS3 was blocked. Our data show that SOCS3 expression enhances apoptosis in the H/R model. In conclusion, up-regulating miR-30c-5p protects cells from H/R -induced apoptosis and induces cell proliferation; furthermore, HIF1α markedly contributes to this protective effect. MiR-30c-5p stabilizes HIF1α expression by targeting SOCS3 to achieve anti-apoptotic and proliferative effects.