Proteomic and phosphoproteomic characterization of cardiovascular tissues after long term exposure to simulated space radiation.

Introduction: It may take decades to develop cardiovascular dysfunction following exposure to high doses of ionizing radiation from medical therapy or from nuclear accidents. Since astronauts may be exposed continually to a complex space radiation environment unlike that experienced on Earth, it is unresolved whether there is a risk to cardiovascular health during long-term space exploration missions. Previously, we have described that mice exposed to a single dose of simplified Galactic Cosmic Ray (GCR5-ion) develop cardiovascular dysfunction by 12 months post-radiation. Methods: To investigate the biological basis of this dysfunction, here we performed a quantitative mass spectrometry-based proteomics analysis of heart tissue (proteome and phosphoproteome) and plasma (proteome only) from these mice at 8 months post-radiation. Results: Differentially expressed proteins (DEPs) for irradiated versus sham irradiated samples (fold-change ≥1.2 and an adjusted p-value of ≤0.05) were identified for each proteomics data set. For the heart proteome, there were 87 significant DEPs (11 upregulated and 76 downregulated); for the heart phosphoproteome, there were 60 significant differentially phosphorylated peptides (17 upregulated and 43 downregulated); and for the plasma proteome, there was only one upregulated protein. A Gene Set Enrichment Analysis (GSEA) technique that assesses canonical pathways from BIOCARTA, KEGG, PID, REACTOME, and WikiPathways revealed significant perturbation in pathways in each data set. For the heart proteome, 166 pathways were significantly altered (36 upregulated and 130 downregulated); for the plasma proteome, there were 73 pathways significantly altered (25 upregulated and 48 downregulated); and for the phosphoproteome, there were 223 pathways significantly affected at 0.1 adjusted p-value cutoff. Pathways related to inflammation were the most highly perturbed in the heart and plasma. In line with sustained inflammation, neutrophil extracellular traps (NETs) were demonstrated to be increased in GCR5-ion irradiated hearts at 12-month post irradiation. NETs play a fundamental role in combating bacterial pathogens, modulating inflammatory responses, inflicting damage on healthy tissues, and escalating vascular thrombosis. Discussion: These findings suggest that a single exposure to GCR5-ion results in long-lasting changes in the proteome and that these proteomic changes can potentiate acute and chronic health issues for astronauts, such as what we have previously described with late cardiac dysfunction in these mice.

Dynamic analysis of predictive biomarkers for radiation therapy efficacy in non-small cell lung cancer patients by next-generation sequencing based on blood specimens.

PURPOSE: Radiotherapy plays an important role in the treatment of non-small cell lung cancer, and the aim of this study was to explore the potential association of single gene mutation or pathway mutations with radiotherapy response using targeted next-generation sequencing (NGS) testing of peripheral blood specimens. MATERIAL AND METHODS: We performed NGS containing 425 genes on peripheral blood specimens from 13 NSCLC patients pre- and post-radiotherapy or post-radiotherapy. Patients whose tumors were in complete response or partial response within 1 month after radiotherapy were classified as a radiotherapy-sensitive group; otherwise, they were categorized as a radiotherapy-resistant group. The relationship between single gene mutations, signaling pathway mutations, dynamic fluctuations in circulating tumor DNA （ctDNA）, and radiotherapy response was investigated. RESULTS: Of these 13 patients，6 patients were categorized as a radiotherapy-sensitive group (46.2%), and 7 patients were categorized as a radiotherapy-resistant group (53.8%). No correlation between single gene mutations and response to radiotherapy. Mutations in the SWI/SNF complex were more likely to occur in the radiotherapy-sensitive group than in the other group (p = 0.07). Among all patients，9 patients underwent NGS tests pre- and post-radiotherapy. Dynamic analysis based on ctDNA before and after treatment revealed that a decrease in ctDNA abundance was observed in all patients in the radiotherapy-sensitive group. CONCLUSIONS: SWI/SNF complex mutations may be potential predictive biomarkers of radiotherapy response. Decreased ctDNA abundance after radiotherapy correlates with better efficacy of radiotherapy.

Circular RNA circBLNK promotes osteosarcoma progression and inhibits ferroptosis in osteosarcoma cells by sponging miR­188­3p and regulating GPX4 expression.

As a newly identified circular RNA (circRNA), the role of circBLNK in cancer progression has not been probed. The objective of the present study was to functionally dissect the role of circBLNK in osteosarcoma (OS) tumorigenesis and progression. With regards of the experimental procedure, the levels of mRNAs and proteins were assessed using reverse transcription­quantitative PCR and western blot analysis, respectively. The subcellular location of circBLNK in OS cells was determined by cell cytosolic/nuclear fractionation assay. Cell ferroptosis ability was assessed through MTT assay. Cell proliferative abilities were assessed by clonogenic and Cell Counting Kit­8 assays, and cell apoptosis was measured using flow cytometry. The relationships among circBLNK, miR­188­3p, and glutathione peroxidase 4 (GPX4) were validated by luciferase reporter and RNA pull­down assays, as well as RNA immunoprecipitation. The stability of circBLNK and linear BLNK was confirmed using RNase R treatment assay. The association between circBLNK expression and overall survival rate was assessed by Kaplan­Meier plot. The correlation between the expression levels of circBLNK, miR­188­3p, and GPX4 in OS tissues was assessed by Pearson's χ2 test. The results revealed that CircBLNK and GPX4 were significantly upregulated in OS tissues, which predicted the poor prognosis. CircBLNK knockdown led to suppressed cell proliferation and enhanced cell apoptosis, an effect that could be reversed by the inhibition of miR­188­3p. In an in vivo circBLNK deficiency model, tumor growth was observed to be markedly suppressed. Moreover, circBLNK deficiency elevated levels of intracellular free iron (Fe2+), malondialdehyde, lipid reactive oxygen species and mitochondrial superoxide, while diminishing mitochondrial membrane potential in Erastin­treated OS cells, which were eliminated by overexpressing GPX4. Furthermore, mechanistic investigations revealed that circBLNK sponged miR­188­3p to regulate the expression of GPX4, thereby affecting OS progression. In conclusion, the present study delineated a new regulatory axis involving circBLNK/miR­188­3p/GPX4 in OS progression, adding to the growing evidence that circRNAs are critical gene regulators in cancer progression.

Dual-functional effect encompassing adsorption and catalysis by Mn-modified iron-based sorbents for arsenic removal: Experimental and DFT study.

Arsenic oxidation plays a crucial role in its removal, which has been identified in numerous studies. However, the mechanisms, especially reaction pathways of arsenic oxidation on sorbent surfaces remain inadequately explored. In this work, the effects of Mn doping on arsenic adsorption and oxidation were first verified by adsorption experiments. Subsequently, DFT calculations were carried out to identify alterations in the adsorption energies, active sites, and oxidation pathways. By integrating the experimental and simulation results, a dual-functional framework encompassing adsorption and catalysis of Mn-modified Fe-based material was distinctly established. For adsorption, the introduction of manganese into iron-based sorbent considerably enhanced As2O3 adsorption owing to the increased active sites available for As2O3 chemisorption and the promotion of surface nucleophilicity. Concerning oxidative catalysis, the incorporation of MnO2 augmented surface catalytic oxidation and provided a substantial amount of active Oload. Consequently, the arsenic oxidation occurring on the Mn-modified sorbent surfaces possessed a lower oxidation RDS energy barrier and a shorter oxidation pathway than those on the bare sorbent surfaces. These experimental and simulation results provide a theoretical basis for the design and application of efficient gaseous arsenic adsorbents.

Establishment and validation of nomograms to predict survival probability of advanced malignant pleural mesothelioma based on the SEER database and a Chinese medical institution.

Objective: The purpose of this study was to build nomograms for predicting the survival of individual advanced pleural mesothelioma (MPM) patients using the Surveillance, Epidemiology, and End Results (SEER) database. Methods: The 1251 patients enrolled from the SEER database were randomized (in a 7:3 ratio) to a training cohort and an internal validation cohort. Eighty patients were enrolled from the Harbin Medical University Cancer Hospital as the external validation cohort. Nomograms were constructed from variables screened by univariate or multivariate Cox regression analyses and evaluated by consistency indices (C-index), calibration plots, and receiver operating characteristic (ROC) curves. Patients from the SEER database who received chemotherapy alone and chemoradiotherapy were statistically paired using propensity score matching of the two groups and performed subgroup analysis in the screened variables. Results: The nomograms are well-structured and well-validated prognostic maps constructed from four variables: gender, histology, AJCC stage, and treatment. All individuals were allocated into high-risk versus low-risk groups based on the median risk score of the training cohort, with the high-risk group having worse OS and CSS in all three cohorts (P<0.05). The outcomes of the subgroup analysis indicated that the advanced MPM patients receiving chemotherapy with or without local radiotherapy do not affect OS or CSS. Conclusion: The accurate nomograms to predict the survival of patients with advanced MPM were built and validated based on an analysis of the SEER database with an external validation cohort. The study suggests that the additional local radiotherapy to chemotherapy does not increase the survival benefit of patients.

Ex Vivo Gene Delivery to Porcine Cardiac Allografts Using a Myocardial-Enhanced Adeno-Associated Viral Vector.

Transplantation, the gold standard intervention for organ failure, is a clinical field that is ripe for applications of gene therapy. One of the major challenges in applying gene therapy to this field is the need for a method that achieves consistent and robust gene delivery to allografts. Normothermic ex vivo perfusion is a growing organ preservation method and a device for cardiac preservation was recently approved by the Food and Drug Administration (FDA) (Organ Care System, OCS™; TransMedics, Inc., Andover, MA); this device maintains donor hearts in a near physiologic state while they are transported from the donor to the recipient. This study describes the administration of recombinant adeno-associated viral vectors (rAAVs) during ex vivo normothermic perfusion for the delivery of transgenes to porcine cardiac allografts. We utilized a myocardial-enhanced AAV3b variant, SASTG, assessing its transduction efficiency in the OCS perfusate relative to other AAV serotypes. We describe the use of normothermic ex vivo perfusion to deliver SASTG carrying the Firefly Luciferase transgene to porcine donor hearts in four heterotopic transplant procedures. Durable and dose-dependent transgene expression was achieved in the allografts in 30 days, with no evidence of off-target transgene expression. This study demonstrates the feasibility and efficiency of delivering genes to a large animal allograft utilizing AAV vectors during ex vivo perfusion. These findings support the idea of gene therapy interventions to enhance transplantation outcomes.

Looking on the horizon; potential and unique approaches to developing radiation countermeasures for deep space travel.

Future lunar missions and beyond will require new and innovative approaches to radiation countermeasures. The Translational Research Institute for Space Health (TRISH) is focused on identifying and supporting unique approaches to reduce risks to human health and performance on future missions beyond low Earth orbit. This paper will describe three funded and complementary avenues for reducing the risk to humans from radiation exposure experienced in deep space. The first focus is on identifying new therapeutic targets to reduce the damaging effects of radiation by focusing on high throughput genetic screens in accessible, sometimes called lower, organism models. The second focus is to design innovative approaches for countermeasure development with special attention to nucleotide-based methodologies that may constitute a more agile way to design therapeutics. The final focus is to develop new and innovative ways to test radiation countermeasures in a human model system. While animal studies continue to be beneficial in the study of space radiation, they can have imperfect translation to humans. The use of three-dimensional (3D) complex in vitro models is a promising approach to aid the development of new countermeasures and personalized assessments of radiation risks. These three distinct and unique approaches complement traditional space radiation efforts and should provide future space explorers with more options to safeguard their short and long-term health.

Structural design and analysis of pneumatic prostate seed implantation robot applied in magnetic resonance imaging environment.

BACKGROUND: The method of MRI (Magnetic Resonance Imaging) image-guided robot for prostate seed implantation has developed rapidly in recent years. During the operation, although the puncture effect guided by MRI is very good, it is difficult for conventional robots driven by motors to work normally in this environment, which reduces the accuracy of seed implantation and affects the treatment effect. METHODS: First, this paper designs a pneumatic prostate seed implantation robot that is compatible with MRI; the robot is composed of an execution module and an adjustment module, and can complete the positioning and adjustment of the robot's needle entry point, the pose adjustment of the puncture needle and the completion of seed implantation in the MRI space; meanwhile, the statics simulation analysis of its key components is carried out. Then, the kinematics analysis was carried out according to the designed robot structure, and the relationship between the posture of the needle tip and the change of the pneumatic cylinder was obtained; meanwhile, using MATLAB 2020 software, combined with the method of Monte Carlo random number sampling, the simulation analysis of the workspace was carried out. Finally, an experimental prototype is constructed to conduct puncture accuracy experiments, workspace experiments and performance comparison tests in MRI environment. RESULTS: The statics simulation results verify that the key components of the robot designed in this paper can meet the strength requirements of the robot. The simulation results of the workspace meet the requirements of space surgery for prostate seed implantation under the guidance of MRI environment. The puncture accuracy experimented to verify that increasing the puncture speed can improve the seed implantation accuracy, and the puncture deviation of the robot is less than the average deviation of the doctor's actual operation by 6.5 mm. The working space experiment shows that the pitch range is -23.3°~27.8°, the movement range in the X direction is 0~210 mm, the movement range in the Y direction is 0~101 mm, and the lifting range in the Z direction is 0~81 mm, which meets the workspace requirements under MRI. The performance comparison test results in the MRI environment show that the robot is well compatible with MRI instruments. CONCLUSIONS: The pneumatic prostate seed implantation robot designed in this paper has a reasonable structure and stable dynamic performance output, and can perform precise surgical operations in the MRI strong magnetic environment. The research work in this paper provides a design reference for the related research on the positioning accuracy of minimally invasive puncture surgery guided by MRI images.

Metabolomic and Pathway Changes in Large-Leaf, Middle-Leaf and Small-Leaf Cultivars of Camellia sinensis (L.) Kuntze var. niaowangensis.

As an economically important crop, tea is widely cultivated in more than 50 countries and has numerous health benefits. Metabolomics has considerable advantages in the analysis of small molecules and has been widely used in tea science. We applied a metabolomic method to evaluate the dynamic changes in metabolites and pathways in the large-, middle- and small-leaf cultivars of Camellia sinensis (L.) Kuntze var. niaowangensis grown in the same area from Yunwu Mountain. The results indicate that flavonoid biosynthesis, stilbenoid, diarylheptanoid and gingerol biosynthesis, citrate cycle (TCA cycle), and propanoate metabolism may play important roles in the differences among cultivars. The levels of tea polyphenols, flavonoids and amino acids may impact the sensory properties of teas of different cultivars. Our results may help to elucidate the mechanism underlying the difference in tea quality and offer references for the breeding of high-quality tea cultivars.

Removal of gas-phase arsenic and selenium in flue gas by a new combined spray-and-scattered-bubble technology based on ammonia desulphurization.

The integrated control of multiple pollutants is a promising approach for efficient and economical pollution reduction. Inspired by the simultaneous removal of SO2 and NOx by the spray-and-scattered-bubble (SSB) technology, this paper further explores gas phase arsenic and selenium removal ability of this new technology. Ammonia concentration, SO2 concentration, liquid/gas ratio and immersion depth, which are the key operating parameters of SSB technology, are evaluated to determine their effect on arsenic and selenium removal. The experimental results indicate that ammonia concentration and SO2 will facilitate the simultaneous removal of arsenic and selenium by SSB technology. However, the excess ammonia concentration and SO2 should avoided to prevent the decrease in removal efficiency caused by the ammonia escape, increased mass transfer resistance, and mechanical carry-over. The maximum removal efficiency for arsenic can be obtained at the liquid-gas ratio of 10 L/m3, and for selenium, the maximum removal efficiency will be reached at 14 L/m3. For the technology of spray-and-scattered-bubble, chemical reaction and mass transfer jointly play the role in contaminant removal. By changing the immersion depth and measuring the corresponding pressure drop, the weight assigned to the effect of chemical reaction and mass transfer effect could be ascertained to a certain degree. It is speculated that chemical reaction will play a more important role for selenium removal in the bubble zone than the mass transfer. Moreover, for arsenic, mass transfer effect will play a more important role than chemical reaction. The sensitivity analysis for simultaneous removal of arsenic and selenium by SSB technology indicating that the variation of operating conditions will lead to a greater change in arsenic removal as compared with selenium.

The spirobichroman-based polyimides with different side groups: from structure-property relationships to chain packing and gas transport performance.

Spirobichroman-based polymers with high gas permeability and selectivity are promising for their applications as membranes in gas separation. In this study, three spirobichroman-based polyimides (PIs; 6FDA-FH, 6FDA-DH, and 6FDA-MH) were synthesised by the polyreaction between diamines containing different substituents (benzene ring, pyridine ring, and methyl group) and 4,4'-(hexafluoroisopropylidene)-diphthalic anhydride (6FDA). The physical properties, gas transport behaviour, d-spacing, dihedral angle of molecules, and fractional free volume of the PIs were investigated through experiments and molecular simulations. The PIs exhibited excellent thermal stability and good solubility in common organic solvents. The gas permeability of the PIs was investigated; the results highlighted the critical role of the substituents in the enhancement of the gas separation performance of polymer membranes. Detailed analysis of the PIs showed that 6FDA-FH exhibits the highest gas permeability. This can be ascribed to the loose packing of the polymer chain owing to the increased dihedral angle between the two planes. However, the methyl substituent in 6FDA-MH disrupts the polymer chain packing rather than changing the dihedral angle between the two planes, thus enhancing the gas permeability of 6FDA-MH. Furthermore, 6FDA-DH exhibited the highest CO2/CH4 selectivity, which is attributed to the CO2 affinity of the polymer containing the pyridine unit.

Clinical efficacy and safety of apatinib as maintenance treatment in patients with advanced esophageal squamous cell carcinoma.

Background: To investigate the clinical efficacy, safety and prognostic factors of apatinib therapy as maintenance treatment in patients with advanced esophageal squamous cell carcinoma. Methods: We selected 46 patients with advanced esophageal squamous cell carcinoma treated with radiotherapy and chemotherapy in our hospital from January 2017 to February 2019, all of whom were treated with apatinib. We analyzed the clinical efficacy, adverse reactions and prognostic factors. Meanwhile, the expression of VEGFR-2 and NF-kB was detected by the immunohistochemical SABC method. Results: The oral treatment of apatinib in the VEGFR-2 and NF-kB positive groups was better than that in the negative groups. The disease control rate was 67.39%. The main adverse reactions were hypertension (60.87%). The degree of adverse reactions was mainly grade 1-2. Cox multivariate regression analysis showed that the degree of adverse reactions and ECOG score were independent factors affecting OS in patients with advanced esophageal squamous cell carcinoma. Conclusion: The positive expression of VEGFR-2 and NF-kB is expected to be the molecular target of oral apatinib targeted therapy for esophageal cancer. Apatinib has a certain clinical effect as the maintenance treatment for advanced esophageal squamous cell carcinoma patients, with mild adverse reactions and high safety.

Zbtb7b suppresses aseptic inflammation by regulating m6A modification of IL6 mRNA.

Radiotherapy is a crucial approach for treating tumors. However, radiation-induced aseptic inflammation is a common complication. Radiation pneumonitis is the acute manifestation of radiation-induced lung disease, and interleukin 6 (IL-6) is a major proinflammatory cytokine involved in radiation-induced lung injury. Here we found that silencing Zinc finger and BTB domain-containing protein 7B (Zbtb7b) resulted in higher radiation-induced IL-6 production in THP1 cells and BEAS-2B lung bronchial epithelial cells. Mechanistically, Zbtb7b recruited RNA demethylase ALKBH5 to IL6 mRNA. Subsequentially, it demethylated N6-methyladenosine (m6A) modification of IL6 mRNA and inhibited its nuclear export. Thus, Zbtb2b epigenetically suppresses irradiation-induced IL-6 production in the lungs via inhibiting the m6A modification and nucleocytoplasmic transport of IL6 mRNA, serving as a new potential predictive marker and therapeutic target in radiation pneumonitis treatment.

Erratum: Hispidulin prevents hypoxia-induced epithelial-mesenchymal transition in human colon carcinoma cells.

[This corrects the article on p. 1047 in vol. 5, PMID: 26045985.].

Association of PTEN Gene SNPs rs2299939 With PFS in Patients With Small Cell Lung Cancer Treated With Early Radiotherapy.

Lung cancer has higher morbidity and mortality than most cancers. It is common that there are some phenomenons of secondary drug resistance, radiotherapy resistance and poor prognosis during the treatment of small cell lung cancer (SCLC). Recent studies revealed that the single-nucleotide polymorphisms (SNPs) are associated with the curative effect among patients with the same pathological type and stage. Our study analyzed the start time of radiotherapy and the relationship between PTEN gene rs2299939 polymorphisms and survival time among 116 SCLC patients. The results showed that early radiotherapy significantly improved the time of survival in patients compared with late radiotherapy ( P = 0.029). Simultaneously, the study found that patients with the rs2299939 AA genotype showed significant sensitivity to both early and late radiotherapy, but early radiotherapy is better. The median survival time of CC genotype patients was 12 months in the early radiotherapy group while it was 9 months in the late radiotherapy group, thus recommending early radiotherapy among these patients. In addition, it was found that rs2299939 could regulate the expression of related genes in peripheral blood and lung tissues by eQTL analysis. This study revealed that the early radiotherapy could prolong the PFS of SCLC and shall be performed in SCLC treatment.

Application effect of apatinib in patients with failure of standard treatment for advanced malignant tumours.

BACKGROUND: In recent years, targeted therapy has received widespread attention. Among these therapies, anti-angiogenic targeted drugs have become one of the hotspots of research. Apatinib is a novel oral small molecule anti-angiogenic agent that has been clinically tested in a variety of solid tumours. The aim of this study was to investigate the efficacy of apatinib in patients with advanced malignant tumours and failure of standard therapy. METHODS: We collected 41 patients with advanced malignant tumours in our department; all tumours were pathologically confirmed as malignant. All patients received apatinib after failure of standard therapy: 500 mg/dose, one dose/d, orally 30 min after a meal, until progressive disease or intolerable adverse reactions occurred. When there was a second- or third-degree adverse reaction associated with apatinib during treatment, apatinib treatment could be suspended or reduced to 250 mg/dose. Clinical efficacy and progression-free survival were assessed according to RECIST1.1, and adverse reactions were observed. RESULTS: Efficacy assessment was available for 31 patients with a median progression-free survival time of 2.66 months; the objective response rate and disease control rates were 16.1 and 64.5%, respectively. The disease control rates of the patients with lower Eastern Cooperative Oncology Group scores (1-2 points) and with fewer metastatic sites (< 3 sites) were higher than those of the patients with higher scores (3 points) and with more metastatic sites (≥3 sites), respectively (all P < 0.05). The most common adverse reactions were hypertension, neutropenia and hand-foot syndrome. CONCLUSION: For patients with advanced malignant tumours with failure of standard therapy, administration of apatinib can still result in good efficacy. The efficacy of apatinib is better in patients with a higher performance status and lower degree of tumour progression.

Curcumin protects against palmitic acid-induced apoptosis via the inhibition of endoplasmic reticulum stress in testicular Leydig cells.

BACKGROUND: Palmitic acid (PA) is a common saturated fatty acid that induces apoptosis in various types of cells, including testicular Leydig cells. There is evidence suggesting that PA is increased in patients with obesity and that PA-induced cell apoptosis may play an important role in obesity-related male infertility. Curcumin, a natural polyphenol, has been reported to exert cytoprotective effects in various cell types. However, the cytoprotective effect of curcumin against PA-induced apoptosis in Leydig cells remains unknown. Therefore, the current study was performed to investigate the protective effects of curcumin in response to PA-induced toxicity and apoptosis in murine Leydig tumor cell line 1 (MLTC-1) cells and explore the mechanism underlying its anti-apoptotic action. METHODS: MLTC-1 cells were cultured in Roswell Park Institute-1640 medium and divided into five groups. First four groups were treated with 50-400 µM PA, 400 µM PA + 5-40 µM curcumin, 400 µM PA + 500 nM 4-phenylbutyric acid (4-PBA, an endoplasmic reticulum (ER) stress inhibitor), and 500 nM thapsigargin (TG, an ER stress inducer) + 20 µM curcumin, respectively, followed by incubation for 24 h. Effects of PA and/or curcumin on viability, apoptosis, and ER stress in MLTC-1 cells were then determined by cell proliferation assay, flow cytometry, and western blot analysis. The fifth group of MLTC-1 cells was exposed to 400 µM of PA and 5 IU/mL of human chorionic gonadotropin (hCG) for 24 h in the absence and presence of curcumin, followed by measurement of testosterone levels in cell-culture supernatants by enzyme-linked immunosorbent assay (ELISA). Rats fed a high-fat diet (HFD) were treated with or without curcumin for 4 weeks, and the testosterone levels were detected by ELISA. RESULTS: Exposure to 100-400 µM PA reduced cell viability, activated caspase 3, and enhanced the expression levels of the apoptosis-related protein BCL-2-associated X protein (BAX) and ER stress markers glucose-regulated protein 78 (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP) in MLTC-1 cells. Treating cells with 500 nM 4-PBA significantly attenuated PA-induced cytotoxicity through inhibition of ER stress. Curcumin (20 µM) significantly suppressed PA- or TG-induced decrease in cell viability, caspase 3 activity, and the expression levels of BAX, CHOP, and GRP78. In addition, treating MLTC-1 cells with 20 µM curcumin effectively restored testosterone levels, which were reduced in response to PA exposure. Similarly, curcumin treatment ameliorated the HFD-induced decrease in serum testosterone level in vivo. CONCLUSIONS: The present study suggests that PA induces apoptosis via ER stress and curcumin ameliorates PA-induced apoptosis by inhibiting ER stress in MLTC-1 cells. This study suggests the application of curcumin as a potential therapeutic agent for the treatment of obesity-related male infertility.

ERK-dependent proteasome degradation of Txnip regulates thioredoxin oxidoreductase activity.

Dynamic control of thioredoxin (Trx) oxidoreductase activity is essential for balancing the need of cells to rapidly respond to oxidative/nitrosative stress and to temporally regulate thiol-based redox signaling. We have previously shown that cytokine stimulation of the respiratory epithelium induces a precipitous decline in cell S-nitrosothiol, which depends upon enhanced Trx activity and proteasome-mediated degradation of Txnip (thioredoxin-interacting protein). We now show that tumor necrosis factor-α-induced Txnip degradation in A549 respiratory epithelial cells is regulated by the extracellular signal-regulated protein kinase (ERK) mitogen-activated protein kinase pathway and that ERK inhibition augments both intracellular reactive oxygen species and S-nitrosothiol. ERK-dependent Txnip ubiquitination and proteasome degradation depended upon phosphorylation of a PXTP motif threonine (Thr349) located within the C-terminal α-arrestin domain and proximal to a previously characterized E3 ubiquitin ligase-binding site. Collectively, these findings demonstrate the ERK mitogen-activated protein kinase pathway to be integrally involved in regulating Trx oxidoreductase activity and that the regulation of Txnip lifetime via ERK-dependent phosphorylation is an important mediator of this effect.