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Signals triggered through the receptors on the plasma membrane of innate and adaptive immune cells are regulated in space and time (spatial-temporal). While the basic understanding of the temporal events of the signaling cascade i...
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Signals triggered through the receptors on the plasma membrane of innate and adaptive immune cells are regulated in space and time (spatial-temporal). While the basic understanding of the temporal events of the signaling cascade initiated at the plasma membrane has remained a longstanding focus, the insights into the spatial distribution of signaling proteins and their reorganization during signaling process is under intense investigation. It has been proposed that membrane rafts on the plasma membrane provide a platform for the organization of signaling molecules during initiation and/or regulation of membrane signaling in a variety of cell types. While the merit of methods to investigate these nanometer size domains are being debated, the details of their role in signal transduction remain a hot topic of investigation. In a Keystone Symposium on "Lipid Rafts and Cell Function" in 2006 membrane rafts were defined as small (10-200 run), heterogeneous, highly dynamic, sterol- and sphingolipid-enriched domains that compartmentalize cellular processes. Small rafts can sometimes be stabilized to form larger platforms through protein-protein and protein-lipid interactions. Small dynamic and compositionally heterogeneous nature of membrane rafts has been proposed to be central to their functional role. A number of signaling proteins are either housed in membrane rafts or traffic through these cholesterol-rich nano-domains during cell signaling. It has been suggested that small and dynamic nature of each membrane raft on an un-stimulated plasma membrane may be key to its existence as "incomplete signaling unit" and therefore contributing to the quiescent state of the cell. Coalescence of membrane rafts on the plasma membrane during cell stimulation allow congregation of signaling proteins in the rafts, thereby promoting their molecular interactions and generation of signals that cascade to the cell interior. Over the past decade it has become increasingly clear that signaling through pattern recognition receptors (PRR) in innate immune cells (e.g., dendritic cells (DC) and macrophages) and multi-chain antigen receptor in cells of adaptive immunity (e.g., B and T cells) either get initiated in membrane rafts or propagated through these nano-domains. While the details related to the involvement of membrane rafts are currently being worked-out, this new paradigm in cell signaling has direct implications in initiation/regulation of immune response during normal and abnormal immune responses. This thematic issue on "Membrane Rafts and Signaling" reviews some important aspects of raft biology and provides an additional possibility of rational drug design to interrupt or modulate signals in immune cells.
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In many cell types, the potential of reactive oxygen species to induce death processes has been largely demonstrated. Studies in spermatozoa have associated the imbalance of reactive oxygen species and phosphatidylserine externali...
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In many cell types, the potential of reactive oxygen species to induce death processes has been largely demonstrated. Studies in spermatozoa have associated the imbalance of reactive oxygen species and phosphatidylserine externalisation as an apoptosis marker. However, the lack of consensus about time effect in the joint expression of these and other death markers has made it difficult to understand the set of mechanisms influenced beyond the concentration effect of reactive oxygen species to stimulate cell death. Here, the plasma membrane permeability and integrity, phosphatidylserine externalisation and mitochondrial membrane potential were jointly evaluated as death markers in human spermatozoa stimulated with H2O2. The results showed a profound and sustained effect of dissipation in the mitochondrial membrane potential and an increased phosphatidylserine externalisation in human spermatozoa exposed to 3 mmol(-1) of H2O2 at 30 min. This was followed by an increased membrane permeability after 45 min. The last observed event was the loss of cell membrane integrity at 60 min. In conclusion, mitochondria are rapidly affected in human spermatozoa exposed to reactive oxygen species, with the barely detectable mitochondrial membrane potential coexisting with the high phosphatidylserine externalisation in cells with normal membrane permeability.
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Cell membrane cloaking technique is bioinspired nanotechnology that takes advantage of naturally derived design cues for surface modification of nanoparticles. Unlike modification with synthetic materials, cell membranes can repli...
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Cell membrane cloaking technique is bioinspired nanotechnology that takes advantage of naturally derived design cues for surface modification of nanoparticles. Unlike modification with synthetic materials, cell membranes can replicate complex physicochemical properties and biomimetic functions of the parent cell source. This technique indeed has the potential to greatly augment existing nanotherapeutic platforms. Here, we provide a comprehensive overview of engineered cell membrane-based nanotherapeutics for targeted drug delivery and biomedical applications and discuss the challenges and opportunities of cell membrane cloaking techniques for clinical translation.
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Black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs), which are major atmospheric pollutants in China, are hazardous to humans following inhalation. BC can be oxidized by PAHs forming secondary particles of which the heal...
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Black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs), which are major atmospheric pollutants in China, are hazardous to humans following inhalation. BC can be oxidized by PAHs forming secondary particles of which the health effects are unknown. In this study, carbon black (CB) was used to simulate BC to reveal the adverse effects of 1,4-naphthoquinone aged carbon black (CB/1.4-NQ) particles on the membrane of human bronchial epithelial (16HBE) cells. It was showed that, the cell viability, cell membrane fluidity, membrane potential and mitochondrial membrane potential were significantly decreased after 16HBE cells were treated with CB, 1,4-NQ or CB/1.4-NQ. Meanwhile, the cell membrane permeability and intracellular Ca~(2+) concentration were increased. CB/1.4-NQ could induce more adverse effects on cell membrane than single CB treated, while less than 1,4-NQ. The results indicated that CB/1,4-NQ particles in the atmosphere may cause more damage to health, and the effects on cell membrane can be used to evaluate the early health effects of the paniculate matter exposure.
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This work demonstrates, for the first time, the potential of using multi-parameter flow cytometry to monitor changes in the microbial cytoplasmic membrane integrity and polarization during microbial fuel cells (MFC) operation. Suc...
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This work demonstrates, for the first time, the potential of using multi-parameter flow cytometry to monitor changes in the microbial cytoplasmic membrane integrity and polarization during microbial fuel cells (MFC) operation. Such information is crucial to follow the dynamics of bacteria colonization of the electrodes and their viability maintenance during electrical current production. Interestingly, the results show that during voltage production, the electrostatic gradients of the bacteria cytoplasmic membrane are disturbed, leading to depolarization of a subpopulation (where less than 40% of the cells were polarized). Once the voltage dropped, due to substrate limitation, several cells in the anode supernatant restored their polarized state. This process was reversible and observed over more than 4 cycles of fresh substrate addition. Similar power outputs induced similar membrane polarization results, regardless of the substrate used. The percentage of non-viable cells was maintained constant during current production. This study opens new opportunities to monitor cell behavior, and thus increase the knowledge of dynamic mechanisms responsible for current production at the individual cell level. This technique could be of great interest for the development of new MFC configurations and optimization of MFC operation conditions toward increased performance.
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Sea nettle (Chrysaora quinquecirrha) venom (CQV) is known to be toxic to the cardiac, respiratory, renal and hepatic systems in animal models. However, the mechanism of toxicity of CQV on hepatocytes is unknown. We utilized isolat...
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Sea nettle (Chrysaora quinquecirrha) venom (CQV) is known to be toxic to the cardiac, respiratory, renal and hepatic systems in animal models. However, the mechanism of toxicity of CQV on hepatocytes is unknown. We utilized isolated rat hepatocytes in culture and measured percentage total lactate dehydrogenase (LDH) release after direct exposure to CQV. Toxicity of CQV in this system produced a linear multiple-dose response curve as well as a linear single-dose kinetics curve. Neither extracellular calcium concentration nor intracellular calcium chelation had a statistically significant effect on the toxicity of CQV in our hepatocyte model. From these results it appears that CQV does not form large membrane channels similar to complement, nor does calcium appear to play a major role in the mechanism of toxicity in hepatocytes. The isolated rat hepatocyye culture and measure of LDH release provided a relatively simple and reproducible model for examining toxicity of CQV. Copyright (C) 1996 Elsevier Science Ltd [References: 14]
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Cell membranes experience frequent stretching and poking: from cytoskeletal elements, from osmotic imbalances, from fusion and budding of vesicles, and from forces from the outside. Are the ens
Cell membranes experience frequent stretching and poking: from cytoskeletal elements, from osmotic imbalances, from fusion and budding of vesicles, and from forces from the outside. Are the ensuing changes in membrane tension localized near the site of perturbation, or do these changes propagate rapidly through the membrane to distant parts of the cell, perhaps as a mechanical mechanism of long‐range signaling? Literature statements on the timescale for membrane tension to equilibrate across a cell vary by a factor of ≈10
6
. This study reviews and discusses how apparently contradictory findings on tension propagation in cells can be evaluated in the context of 2D hydrodynamics and poroelasticity. Localization of tension in the cell membrane is likely critical in governing how membrane forces gate ion channels, set the subcellular distribution of vesicle fusion, and regulate the dynamics of cytoskeletal growth. Furthermore, in this study, it is proposed that cells can actively regulate the degree to which membrane tension propagates by modulating the density and arrangement of immobile transmembrane proteins. Also see the video abstract here
https://youtu.be/T6K7AIAqqBs
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摘要 :AbstractThe plasma membrane separates the interior of cells from the outside environment. The membrane tension, defined as the force per unit length acting on a cross-section of membrane, regulates many vital biological processes....
展开AbstractThe plasma membrane separates the interior of cells from the outside environment. The membrane tension, defined as the force per unit length acting on a cross-section of membrane, regulates many vital biological processes. In this review, we summarize the first historical findings and the latest advances, showing membrane tension as an important physical parameter in cell biology. We also discuss how this parameter must be better integrated and we propose experimental approaches for key unanswered questions.]]>
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We improved our previously reported highly sensitive bacteria detection method called electropermeabilization-assisted dielectrophoretic impedance measurement (EPA-DEPIM), which counts the number of bacteria by measuring changes i...
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We improved our previously reported highly sensitive bacteria detection method called electropermeabilization-assisted dielectrophoretic impedance measurement (EPA-DEPIM), which counts the number of bacteria by measuring changes in impedance. EPA-DEPIM involves two processes: collection of bacteria by dielectrophoresis (DEP), followed by electropermeabilization (EP) of the cell membranes. In DEP, bacterial cells in aqueous solution are collected on microelectrodes by the dielectrophoretic force. In EP, a pulse-like rectangular wave is applied to the collected cells to disrupt their membranes. This increases the signal sensitivity because the disrupted membranes release intracellular ions that increase the change in impedance. However, the pulse-like EP wave creates a strong electric field that causes metal ions to be released from the microelectrodes, increasing the blank signal to levels comparable to that for a low-concentration Escherichia coli suspension (102 cells/ml). To address this problem, we demonstrated the efficacy of two types of pretreatment applied before the EP wave: chemical pretreatment by exposure to hydrogen peroxide, and physical pretreatment by a small pulse-like voltage. Both pretreatments successfully intensified the change in impedance even at a lower EP voltage.
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Pluripotent stem cells are a unique cell type with promising potential in regenerative and personalized medicine. Yet the difficulty to understand and coax their seemingly stochastic differentiation and spontaneous self-renewal ha...
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Pluripotent stem cells are a unique cell type with promising potential in regenerative and personalized medicine. Yet the difficulty to understand and coax their seemingly stochastic differentiation and spontaneous self-renewal have largely limited their clinical applications. A call has been made by numerous researchers for a better characterization of surface proteins on these cells, in search of biomarkers that can dictate developmental stages and lineage specifications, and can help formulate mechanistic insight of stem-cell fate choices. In the past two decades, proteomics has gained significant recognition in profiling surface proteins at high throughput. This review will summarize the impact of these studies on stem-cell biology, and discuss the used proteomic techniques. A systematic comparison of all the techniques and their results is also attempted here to help reveal pros, cons, and the complementarity of the existing methods. This awareness should assist in selecting suitable strategies for stem-cell related research, and shed light on technical improvements that can be explored in the future.
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