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1
Content available remote Autophagy - Adaptive Molecular Mechanisms in Condition of Starvation
100%
EN
Autophagy is an extremely old process during which long-lived proteins and cellular organelles are removed by means of lysosomes. Autophagy may be caused by cellular stress mechanisms. Research has proven that autophagy plays a key role in obtaining nutrients and adapting to the conditions of starvation. Owing to this, it takes part in maintaining homeostasis in cytoplasm and cell nucleus. This objective may be achieved through a number of ways. Depending on the manner in which a substrate connects with the lysosome, we can talk about macroautophagy and microautophagy. Additionally, some authors also distinguish a chaperone-mediated autophagy. The article presented below describes molecular mechanisms of each type of autophagy and focuses particularly on macroautophagy, which is the best understood of all the autophagy types.
EN
Cytotoxic CD8+ cells play an important role in determining host response to tumor, thus chemotherapy is potentially dangerous as it may lead to T cells depletion. The purpose of this study was to elucidate the propensity of quiescent and proliferating human CD8+ cells to undergo cell death upon treatment with curcumin, a natural dye in Phase I of clinical trials as a prospective chemopreventive agent. Methods: We treated human quiescent or proliferating CD8+ cells with 50 µM curcumin or irradiated them with UVC. Cell death symptoms such as decreased cell viability, chromatin condensation, activation of caspase-3 and specific DFF40/CAD endonuclease and oligonucleosomal DNA fragmentation were analyzed using MTT test, microscopic observation, Western blotting and flow cytometry. Results: Curcumin decreased cell viability, activated caspase-3 and decreased the level of DFF45/ICAD, the inhibitor of the DFF40/CAD endonuclease. However, this did not lead to oligonucleosomal DNA degradation. In contrast, UVC-irradiated proliferating, but not quiescent CD8+ cells revealed molecular and morphological changes characteristic for apoptosis, including oligonucleosomal DNA fragmentation. Curcumin can induce cell death in normal human lymphocytes both quiescent and proliferating, without oligonucleosomal DNA degradation which is considered as a main hallmark of apoptotic cell death. Taking into account the role of CD8+ cells in tumor response, their depletion during chemotherapy could be particularly undesirable.
3
88%
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2016
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tom nr 4
78--82
EN
Rapid retrospective biological dosimetry allows absorbed dose evaluation post exposure to ionizing radiation. One of the main tools of biodosimetry is based on the analysis of the effects resulting from the impact of ionizing radiation on the cell. Various cytogenetic tests give possibility of the accurate dose estimation. To investigate cell response to radiation one performs the analysis of biomarkers approved by International Atomic Energy Agency e.g. the analysis of dicentric chromosomes or micronuclei frequency. Micronucleus test is relatively a faster and therefore more effective method to study changes in the genetic material, induced by various genotoxic agents. This study confirms that micronulei frequency and nuclear division index analysis allows for appropriate absorbed dose estimation when it comes to ionizing radiation. In order to further optimize and facilitate the micronucleus assay and other cytogenetic tests in rapid retrospective biological dosimetry, the research are still ongoing.
EN
Proteolytic enzymes, also known as peptidases or proteases, are protein catalysts that are primarily responsible for the hydrolysis of a peptide (amide) bond in peptide and protein substrates. By selective hydrolysis of selected substrates, these enzymes control many physiologically important processes including programmed cell death, blood coagulation cascade, protein maturation, fibrinolysis and many others. On the other hand, however, the imbalance in proteases activity leads to the development of diseases, including cancer, neurodegenerative diseases and coronary diseases etc.. In recent decades there has been great progress in studying the biological functions of many proteolytic enzymes. These observations were made possible through the use of various research techniques including genomics, epigenomics and proteomics. However, a major limitation of these techniques is the lack of information about the exact catalytic activity of the enzymes. For this reason, chemical probes are the most convenient toll for functional investigation of proteolytic enzymes. According to the generally accepted convention, chemical probes are compounds that can detect the catalytic activity of proteolytic enzymes. In general, chemical-based probes (activity-based probes, ABPs) consist of three main components: (1) a reactive binding group that binds permanently to the enzyme active site, (2) a recognition sequence (usually a peptide), which is responsible for the selective binding of a given probe to an individual enzyme or group of enzymes, and (3) a tag, mainly a fluorophore, enabling for detection of the probe-enzyme complex. However, the current limitation of ABPs is that only up to four enzymes can be detected and visualized in parallel, which significantly impedes their application for multi-parametric analysis. To date, the detection of proteases with the use of ABPs was limited to individual enzymes being investigated one by one, thus the obtained picture was far from being complete. In this review we describe the development of a new type of enzyme ABPs, so called TOF-probes that are compatible with mass cytometry format. The application of metal isotopes instead of fluorophores, makes possible to significantly increase the number of enzymes, which can be simultaneously visualized using chemical probes. Mass cytometry is a revolutionary technology that adopts atomic mass spectrometry into flow cytometry applications. The excellence of this method is that each metal isotope (mostly from lanthanides) has its own peak on mass spectrum, which eliminates the problem of signal overlap, thus allows for monitoring of more than 40 parameters at single cell level.
PL
Autofagia jest bardzo starym procesem, podczas którego przy pomocy lizosomów usuwane są białka o długim okresie półtrwania oraz organella komórkowe. Autofagia może być wywołana przez mechanizmy stresowe dla komórki. Badania dowodzą, że autofagia odgrywa kluczową rolę w pozyskiwaniu składników odżywczych oraz w adaptacji do warunków głodu. Dzięki temu bierze udział w zachowaniu homeostazy w cytoplazmie i jądrze komórki. Osiągnięcie tego celu możliwe jest kilkoma drogami. W zależności od tego w jaki sposób substrat zostaje połączony z lizosomem mówimy o: makroautofagii oraz mikroautofagii. Dodatkowo część autorów wyróżnia również autofagię zależną od chaperonów. W niniejszym artykule opisano mechanizmy molekularne poszczególnych rodzajów autofagii ze szczególną uwagą poświeconą makroautofagii- jako najlepiej poznanemu typowi autofagii.
EN
Autophagy is an extremely old process during which long-lived proteins and cellular organelles are removed by means of lysosomes. Autophagy may be caused by cellular stress mechanisms. Research has proven that autophagy plays a key role in obtaining nutrients and adapting to the conditions of starvation. Owing to this, it takes part in maintaining homeostasis in cytoplasm and cell nucleus. This objective may be achieved through a number of ways. Depending on the manner in which a substrate connects with the lysosome, we can talk about macroautophagy and microautophagy. Additionally, some authors also distinguish a chaperone-mediated autophagy. The article presented below describes molecular mechanisms of each type of autophagy and focuses particularly on macroautophagy, which is the best understood of all the autophagy types.
EN
Mass cytometry is one of the newest and most high-throughput technologies that allows for the investigation of complex biological systems at single cell level. It relies on the use of stable metal isotopes as labels of specific cell markers and therefore, allows for simultaneous analysis of more than 40 parameters at single cell level. In order to fully explore the potential of mass cytometry, researchers are trying to develop new experimental setups based on the application of pure metal isotopes in biological studies. The incorporation of antibodies into mass cytometry setups, while extremely selective and well-validated, limits the analysis as it shows the whole protein pool present in the cell. In our group, we developed new technology that allows for the identification of active forms of proteins-the ones that actively participate in cell signaling pathways. Activity-based probes are the most valuable tools for enzyme activity profiling and for years now they have been in the center of the method called Activity-Based Protein Profiling. Classic activity-based probes consist of three parts: a warhead (electrophilic binding group that covalently modifies enzyme active site), linker (specific peptide sequence or non-specific carbon chain) and the fluorescent tag that allows for enzyme detection and localization inside the cell. Spectral properties of commercially available fluorophores allow for the detection of up to dozen different cell parameters, with the use of various techniques such as confocal microscopy or flow cytometry. To increase the number of analyzed parameters, we designed activity-based probes that possess DOTA chelating moiety that is able to trap one metal atom per one probe. The combination of mass cytometry with highly selective activity-based probes allowed for the development of new technology that grants the possibility of multiparametric analysis of complex biological samples such as blood or cancer tissue. The new type of activity-based probes (so-called TOF-probes) incorporate various inhibitor scaffolds designed with HyCoSuL technology (Hybrid Combinatorial Substrate Libraries). These compounds possess a variety of unnatural amino acids in their structures, which significantly increases their selectivity toward proteases of interest.
EN
We previously demonstrated that the anti-apoptosis protein, survivin, plays a protective role against alcohol-induced gastric injury. Since the endothelium is a primary target of alcohol-induced gastric damage, we investigated whether survivin expression is a key factor in the greater susceptibility of gastric endothelial vs. epithelial cells to alcohol-induced injury. Here, we demonstrate that rat gastric epithelial cells (RGM1 cells, an epithelial cell line derived from normal rat gastric mucosa) expressed 7.5-fold greater survivin protein levels vs. rat gastric endothelial cells. Survivin expression correlated with resistance of gastric epithelial vs. endothelial cells to both alcohol-induced cell damage and alcohol-induced apoptosis. Suppression of survivin protein expression levels using siRNA rendered the gastric epithelial cells as susceptible to both alcohol-induced cell damage and apoptosis as the gastric endothelial cells. Conversely, forced overexpression of survivin by transient transfection rendered gastric endothelial cells as resistant to both alcohol-induced cell damage and apoptosis as mock-transfected gastric epithelial cells. Moreover, overexpression of a threonine-34 to glutamate phosphorylation mimic mutant survivin construct rendered gastric endothelial cells significantly more resistant to alcohol-induced damage and apoptosis vs. mock-transfected gastric epithelial cells. These findings indicate that disparate survivin expression levels can explain the discrepancy between gastric epithelial and endothelial cell susceptibility to alcohol-induced injury; and, that a negative charge at amino acid residue 34 on survivin, such as that which naturally occurs by phosphorylation of threonine-34, enhances its property in conferring gastric mucosal protection.
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