An additional cysteine in a typical 2-Cys peroxiredoxin of Pseudomonas promotes functional switching between peroxidase and molecular chaperone

AbstractPeroxiredoxins (Prx) have received considerable attention during recent years. This study demonstrates that two typical Pseudomonas-derived 2-Cys Prx proteins, PpPrx and PaPrx can alternatively function as a peroxidase and chaperone. The amino acid sequences of these two Prx proteins exhibit 93% homology, but PpPrx possesses an additional cysteine residue, Cys112, instead of the alanine found in PaPrx. PpPrx predominates with a high molecular weight (HMW) complex and chaperone activity, whereas PaPrx has mainly low molecular weight (LMW) structures and peroxidase activity. Mass spectrometry and structural analyses showed the involvement of Cys112 in the formation of an inter-disulfide bond, the instability of LMW structures, the formation of HMW complexes, and increased hydrophobicity leading to functional switching of Prx proteins between peroxidase and chaperone

GPx3-mediated redox signaling arrests the cell cycle and acts as a tumor suppressor in lung cancer cell lines.

Glutathione peroxidase 3 (GPx3), a major scavenger of reactive oxygen species (ROS) in plasma, acts as a redox signal modulator. However, the mechanism underlying GPx3-mediated suppression of cancer cell growth is unclear. The aim of this study was to identify these mechanisms with respect to lung cancer. To enhance the redox modulating properties of GPx3, lung cancer cells were subjected to serum starvation for 12 h, resulting in ROS generation in the absence of oxidant treatment. We then investigated whether suppression of tumorigenesis under conditions of oxidative stress was dependent on GPx3. The results showed that GPx3 effectively suppressed proliferation, migration, and invasion of lung cancer cells under oxidative stress. In addition, GPx3 expression led to a significant reduction in ROS production by cancer cells and induced G2/M phase arrest. We also found that inactivation of cyclin B1 significantly suppressed by nuclear factor-κB(NF-κB) inactivation in lung cancer cells was dependent on GPx3 expression. To further elucidate the mechanism(s) underlying GPx3-medited suppression of tumor proliferation, we next examined the effect of GPx3-mediated redox signaling on the ROS-MKP3-extracellular signal-regulated kinase (Erk)-NF-κB-cyclin B1 pathway and found that GPx3 strongly suppressed activation of the Erk-NF-κB-cyclin B1 signaling cascade by protecting MKP3 (an Erk-specific phosphatase) from the effects of ROS. Thus, this study demonstrates for the first time that the GPx3 suppresses proliferation of lung cancer cells by modulating redox-mediated signals

Anti-Cancer Roles of Probiotic-Derived P8 Protein in Colorectal Cancer Cell Line DLD-1

A novel probiotics-derived protein, P8, suppresses the growth of colorectal cancer (CRC). P8 can penetrate the cell membrane via endocytosis and cause cell cycle arrest in DLD-1 cells through down-regulation of CDK1/Cyclin B1. However, neither the protein involved in the endocytosis of P8 nor the cell cycle arrest targets of P8 are known. We identified two P8-interacting target proteins [importin subunit alpha-4 (KPNA3) and glycogen synthase kinase-3 beta (GSK3β)] using P8 as a bait in pull-down assays of DLD-1 cell lysates. Endocytosed P8 in the cytosol was found to bind specifically to GSK3β, preventing its inactivation by protein kinases AKT/CK1ε/PKA. The subsequent activation of GSK3β led to strong phosphorylation (S33,37/T41) of β-catenin, resulting in its subsequent degradation. P8 in the cytosol was also found to be translocated into the nucleus by KPNA3 and importin. In the nucleus, after its release, P8 binds directly to the intron regions of the GSK3β gene, leading to dysregulation of GSK3β transcription. GSK3β is a key protein kinase in Wnt signaling, which controls cell proliferation during CRC development. P8 can result in a cell cycle arrest morphology in CRC cells, even when they are in the Wnt ON signaling state

Modified reverse shock index predicts early outcomes of heart failure with reduced ejection fraction

Abstract Aims Increased blood pressure (BP) and decreased heart rate (HR) are signs of stabilization in patients admitted for acute HF. Changes in BP and HR during admission and their correlation with outcomes were assessed in hospitalized patients with heart failure (HF) with reduced ejection fraction (HFrEF). Methods A novel modified reverse shock index (mRSI), defined as the ratio between changes in systolic BP and HR during admission, was devised, and its prognostic value in the early outcomes of acute HF was assessed using the Korean Acute HF registry. Results Among 2697 patients with HFrEF (mean age 65.8 ± 14.9 years, 60.6% males), patients with mRSI ≥1.25 at discharge were significantly younger and were more likely to have de novo HF. An mRSI ≥1.25 was associated with a significantly lower incidence of 60‐day and 180‐day all‐cause mortality [hazard ratio (HR) 0.49, 95% confidence interval (CI) 0.31–0.77; HR 0.62, 95% CI 0.45–0.85, respectively], compared with 1 ≤ mRSI < 1.25 (all P < 0.001). Conversely, an mRSI <0.75 was associated with a significantly higher incidence of 60‐day and 180‐day all‐cause mortality (adjusted HR 2.08, 95% CI 1.19–3.62; HR 2.24, 95% CI 1.53–3.27; all P < 0.001). The benefit associated with mRSI ≥1.25 was consistent in sub‐group analyses. The correlation of mRSI and outcomes were also consistent regardless of admission SBP, presence of atrial fibrillation, or use of beta blockers at discharge. Conclusions In patients hospitalized for HFrEF, the mRSI was a significant predictor of early outcomes. The mRSI could be used as a tool to assess patient status and guide physicians in treating patients with HFrEF

Integrative analysis for the discovery of lung cancer serological markers and validation by MRM-MS

<div><p>Non-small-cell lung cancer (NSCLC) constitutes approximately 80% of all diagnosed lung cancers, and diagnostic markers detectable in the plasma/serum of NSCLC patients are greatly needed. In this study, we established a pipeline for the discovery of markers using 9 transcriptome datasets from publicly available databases and profiling of six lung cancer cell secretomes. Thirty-one out of 312 proteins that overlapped between two-fold differentially expressed genes and identified cell secretome proteins were detected in the pooled plasma of lung cancer patients. To quantify the candidates in the serum of NSCLC patients, multiple-reaction-monitoring mass spectrometry (MRM-MS) was performed for five candidate biomarkers. Finally, two potential biomarkers (BCHE and GPx3; AUC = 0.713 and 0.673, respectively) and one two-marker panel generated by logistic regression (BCHE/GPx3; AUC = 0.773) were identified. A validation test was performed by ELISA to evaluate the reproducibility of GPx3 and BCHE expression in an independent set of samples (BCHE and GPx3; AUC = 0.630 and 0.759, respectively, BCHE/GPx3 panel; AUC = 0.788). Collectively, these results demonstrate the feasibility of using our pipeline for marker discovery and our MRM-MS platform for verifying potential biomarkers of human diseases.</p></div