Pro‐apoptotic effect of haem oxygenase‐1 in human colorectal carcinoma cells via endoplasmic reticular stress

Several biological effects of haem oxygenase (HO)‐1, including anti‐inflammatory, antiapoptotic and antioxidative properties were reported; however, the role of HO‐1 in apoptosis is still unclear. In the presence of stimulation by cobalt protoporphyrin (CoPP), an HO‐1 inducer, apoptotic characteristics were observed, including DNA laddering, hypodiploid cells, and cleavages of caspase (Casp)‐3 and poly(ADP) ribose polymerase (PARP) proteins in human colon carcinoma COLO205, HCT‐15, LOVO and HT‐29 cells in serum‐free (SF) conditions with increased HO‐1, but not heat shock protein 70 (HSP70) or HSP90. The addition of 10% foetal bovine serum (FBS) or 1% bovine serum albumin accordingly inhibited CoPP‐induced apoptosis and HO‐1 protein expression in human colon cancer cells. CoPP‐induced apoptosis of colon cancer cells was prevented by the addition of the pan‐caspase inhibitor, Z‐VAD‐FMK (VAD), and the Casp‐3 inhibitor, Z‐DEVD‐FMK (DEVD). N‐Acetyl cysteine inhibited reactive oxygen species‐generated H₂O₂‐induced cell death with reduced intracellular peroxide production, but did not affect CoPP‐induced apoptosis in human colorectal carcinoma (CRC) cells. Two CoPP analogs, ferric protoporphyrin and tin protoporphyrin, did not affect the viability of human CRC cells or HO‐1 expression by those cells, and knockdown of HO‐1 protein expression by HO‐1 small interfering (si)RNA reversed the cytotoxic effect elicited by CoPP. Furthermore, the carbon monoxide (CO) donor, CORM, but not FeSO₄ or biliverdin, induced DNA ladders, and cleavage of Casp‐3 and PARP proteins in human CRC cells. Increased phosphorylated levels of the endoplasmic reticular (ER) stress proteins, protein kinase R‐like ER kinase (PERK), and eukaryotic initiation factor 2α (eIF2α) by CORM and CoPP were identified, and the addition of the PERK inhibitor, GSK2606414, inhibited CORM‐ and CoPP‐induced apoptosis. Increased GRP78 level and formation of the HO‐1/GRP78 complex were detected in CORM‐ and CoPP‐treated human CRC cells. A pro‐apoptotic role of HO‐1 against the viability of human CRC cells via induction of CO and ER stress was firstly demonstrated herein.     

Atomic‐Local Environments of Single‐Atom Catalysts: Synthesis,Electronic Structure,and Activity

Single‐atom catalysts (SACs) hold great promise for maximizing atomic efficiency of supported metals via the ultimate utilization of every single atom. The foreign isolated substitutions anchored on different supports build varieties of local structural centers, changing the physical and chemical properties. Thus, distinct atomic local environments for single‐atom catalysts are essential for determining superior catalytic performance for a wide variety of chemical reactions. The examples of synthesizing single atoms on various supports presented here deepen the understanding of the different structural and electronic properties of SACs, in which the metal single atom does not bind with any other atoms of this metal, but substantially interacts with the support ions. Due to the strong support effects, the ubiquitous aggregation of metal single atoms can be addressed, achieving highly stable SACs. This review discusses recent progress in theoretical electronic effects between atomic dopants and supports, which reveal the electronic structures of various SACs and offers guidance for rational prediction and design of highly stable and reactive SACs. It is argued that tuning this interaction by the selection of the supports toward favorable atomic and electronic structures on the surface should be taken into consideration for the development of more efficient SACs.     

Convergence of Parkin,PINK1, and α-Synuclein on Stress-induced Mitochondrial Morphological Remodeling

Mutations in PARKIN (PARK2), an ubiquitin ligase, cause early onset Parkinson disease. Parkin was shown to bind, ubiquitinate, and target depolarized mitochondria for destruction by autophagy. This process, mitophagy, is considered crucial for maintaining mitochondrial integrity and suppressing Parkinsonism. Here, we report that under moderate mitochondrial stress, parkin does not translocate to mitochondria to induce mitophagy; rather, it stimulates mitochondrial connectivity. Mitochondrial stress-induced fusion requires PINK1 (PARK6), mitofusins, and parkin ubiquitin ligase activity. Upon exposure to mitochondrial toxins, parkin binds α-synuclein (PARK1), and in conjunction with the ubiquitin-conjugating enzyme Ubc13, stimulates K63-linked ubiquitination. Importantly, α-synuclein inactivation phenocopies parkin overexpression and suppresses stress-induced mitochondria fission, whereas Ubc13 inactivation abrogates parkin-dependent mitochondrial fusion. The convergence of parkin, PINK1, and α-synuclein on mitochondrial dynamics uncovers a common function of these PARK genes in the mitochondrial stress response and provides a potential physiological basis for the prevalence of α-synuclein pathology in Parkinson disease.     

iTIS-PseTNC: A sequence-based predictor for identifying translation initiation site in human genes using pseudo trinucleotide composition

Translation is a key process for gene expression. Timely identification of the translation initiation site (TIS) is very important for conducting in-depth genome analysis. With the avalanche of genome sequences generated in the postgenomic age, it is highly desirable to develop automated methods for rapidly and effectively identifying TIS. Although some computational methods were proposed in this regard, none of them considered the global or long-range sequence-order effects of DNA, and hence their prediction quality was limited. To count this kind of effects, a new predictor, called “iTIS-PseTNC,” was developed by incorporating the physicochemical properties into the pseudo trinucleotide composition, quite similar to the PseAAC (pseudo amino acid composition) approach widely used in computational proteomics. It was observed by the rigorous cross-validation test on the benchmark dataset that the overall success rate achieved by the new predictor in identifying TIS locations was over 97%. As a web server, iTIS-PseTNC is freely accessible at http://lin.uestc.edu.cn/server/iTIS-PseTNC. To maximize the convenience of the vast majority of experimental scientists, a step-by-step guide is provided on how to use the web server to obtain the desired results without the need to go through detailed mathematical equations, which are presented in this paper just for the integrity of the new prection method.     

Dynamin1 Is a Novel Target for IRSp53 Protein and Works with Mammalian Enabled (Mena) Protein and Eps8 to Regulate Filopodial Dynamics

Filopodia are dynamic actin-based structures that play roles in processes such as cell migration, wound healing, and axonal guidance. Cdc42 induces filopodial formation through IRSp53, an Inverse-Bin-Amphiphysins-Rvs (I-BAR) domain protein. Previous work from a number of laboratories has shown that IRSp53 generates filopodia by coupling membrane protrusion with actin dynamics through its Src homology 3 domain binding partners. Here, we show that dynamin1 (Dyn1), the large guanosine triphosphatase, is an interacting partner of IRSp53 through pulldown and Förster resonance energy transfer analysis, and we explore its role in filopodial formation. In neuroblastoma cells, Dyn1 localizes to filopodia, associated tip complexes, and the leading edge just behind the anti-capping protein mammalian enabled (Mena). Dyn1 knockdown reduces filopodial formation, which can be rescued by overexpressing wild-type Dyn1 but not the GTPase mutant Dyn1-K44A and the loss-of-function actin binding domain mutant Dyn1-K/E. Interestingly, dynasore, an inhibitor of Dyn GTPase, also reduced filopodial number and increased their lifetime. Using rapid time-lapse total internal reflection fluorescence microscopy, we show that Dyn1 and Mena localize to filopodia only during initiation and assembly. Dyn1 actin binding domain mutant inhibits filopodial formation, suggesting a role in actin elongation. In contrast, Eps8, an actin capping protein, is seen most strongly at filopodial tips during disassembly. Taken together, the results suggest IRSp53 partners with Dyn1, Mena, and Eps8 to regulate filopodial dynamics.     

A High Resolution Computer Tomography Scoring System to Predict Culture-Positive Pulmonary Tuberculosis in the Emergency Department

This study evaluated the use of high-resolution computed tomography (HRCT) to predict the presence of culture-positive pulmonary tuberculosis (PTB) in adult patients with pulmonary lesions in the emergency department (ED). The study included a derivation phase and validation phase with a total of 8,245 patients with pulmonary disease. There were 132 patients with culture-positive PTB in the derivation phase and 147 patients with culture-positive PTB in the validation phase. Imaging evaluation of pulmonary lesions included morphology and segmental distribution. The post-test probability ratios between both phases in three prevalence areas were analyzed. In the derivation phase, a multivariate analysis model identified cavitation, consolidation, and clusters/nodules in right or left upper lobe (except anterior segment) and consolidation of the superior segment of the right or left lower lobe as independent positive factors for culture-positive PTB, while consolidation of the right or left lower lobe (except superior segment) were independent negative factors. An ideal cutoff point based on the receiver operating characteristic (ROC) curve analysis was obtained at a score of 1. The sensitivity, specificity, positivity predictive value, and negative predictive value from derivation phase were 98.5% (130/132), 99.7% (3997/4008), 92.2% (130/141), and 99.9% (3997/3999). Based on the predicted positive likelihood ratio value of 328.33 in derivation phase, the post-test probability was observed to be 91.5% in the derivation phase, 92.5% in the validation phase, 94.5% in a high TB prevalence area, 91.0% in a moderate prevalence area, and 76.8% in moderate-to-low prevalence area. Our model using HRCT, which is feasible to perform in the ED, can promptly diagnose culture-positive PTB in moderate and moderate-to-low prevalence areas.     

Evaluation of the Antitumor Effects of BPR1J-340, a Potent and Selective FLT3 Inhibitor,Alone or in Combination with an HDAC Inhibitor,Vorinostat, in AML Cancer

Overexpression or/and activating mutation of FLT3 kinase play a major driving role in the pathogenesis of acute myeloid leukemia (AML). Hence, pharmacologic inhibitors of FLT3 are of therapeutic potential for AML treatment. In this study, BPR1J-340 was identified as a novel potent FLT3 inhibitor by biochemical kinase activity (IC₅₀ approximately 25 nM) and cellular proliferation (GC₅₀ approximately 5 nM) assays. BPR1J-340 inhibited the phosphorylation of FLT3 and STAT5 and triggered apoptosis in FLT3-ITD⁺ AML cells. The pharmacokinetic parameters of BPR1J-340 in rats were determined. BPR1J-340 also demonstrated pronounced tumor growth inhibition and regression in FLT3-ITD⁺ AML murine xenograft models. The combination treatment of the HDAC inhibitor vorinostat (SAHA) with BPR1J-340 synergistically induced apoptosis via Mcl-1 down-regulation in MOLM-13 AML cells, indicating that the combination of selective FLT3 kinase inhibitors and HDAC inhibitors could exhibit clinical benefit in AML therapy. Our results suggest that BPR1J-340 may be further developed in the preclinical and clinical studies as therapeutics in AML treatments.