scholarly journals More than just a barrier: using physical models to couple membrane shape to cell function

Soft Matter ◽  
2021 ◽  
Author(s):  
Felix Frey ◽  
Timon Idema
Keyword(s):  
Outer Membrane ◽  
Living Cell ◽  
Cell Function ◽  
Physical Models ◽  
Biological Processes ◽  
Membrane Shape

Physical models can help us to infer, from the shape of the outer membrane, which biological processes happen inside the living cell.

scholarly journals Fluid Shear Stress Modulation of Gene Expression in Endothelial Cells

Physiology ◽  
1998 ◽  
Vol 13 (5) ◽  
pp. 241-246 ◽  
Author(s):  
Martin Braddock ◽  
Jean-Luc Schwachtgen ◽  
Parul Houston ◽  
Marion C. Dickson ◽  
Michael J. Lee ◽  
...  
Keyword(s):  
Fluid Shear Stress ◽  
Cell Function ◽  
Shear Stresses ◽  
Biological Processes ◽  
Fluid Shear ◽  
Endothelial Cell Function ◽  
Complex Interactions ◽  
Expression Of Genes ◽  
Modulation Of Gene Expression ◽  
Flowing Blood

The vascular endothelium, lining the blood vessel wall, is constantly exposed to wall shear stresses generated by flowing blood. Gene regulation, critical for endothelial cell function, depends on complex interactions at the promoter level and utilizes overlapping signal transduction cascades to activate the expression of genes involved in many biological processes.

scholarly journals Current approaches to studying membrane organization

F1000Research ◽  
2015 ◽  
Vol 4 ◽  
pp. 1380 ◽  
Author(s):  
Thomas S. van Zanten ◽  
Satyajit Mayor
Keyword(s):  
Outer Membrane ◽  
Local Structure ◽  
Living Cell ◽  
Animal Cell ◽  
Membrane Organization ◽  
Membrane Processes ◽  
Approaches To Studying ◽  
Technological Advances ◽  
Molecular Scale

The local structure and composition of the outer membrane of an animal cell are important factors in the control of many membrane processes and mechanisms. These include signaling, sorting, and exo- and endocytic processes that are occurring all the time in a living cell. Paradoxically, not only are the local structure and composition of the membrane matters of much debate and discussion, the mechanisms that govern its genesis remain highly controversial. Here, we discuss a swathe of new technological advances that may be applied to understand the local structure and composition of the membrane of a living cell from the molecular scale to the scale of the whole membrane.

scholarly journals Identification of Chlamydia pneumoniae-Derived Mouse CD8 Epitopes

2002 ◽  
Vol 70 (7) ◽  
pp. 3336-3343 ◽  
Author(s):  
Anne Sarén ◽  
Steve Pascolo ◽  
Stefan Stevanovic ◽  
Tilman Dumrese ◽  
Mirja Puolakkainen ◽  
...  
Keyword(s):  
T Cell ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Chlamydia Pneumoniae ◽  
Cell Function ◽  
Target Cells ◽  
Heat Shock Protein 60 ◽  
T Cell Epitopes ◽  
Infected Cells

ABSTRACT Chlamydia pneumoniae is a common intracellular human pathogen that has been associated with several severe pathological conditions, including coronary heart disease and atherosclerosis. There is no vaccine against C. pneumoniae infection, but CD8+ T cells have been shown to be crucial for protection during experimental infection. However, the effector functions and epitope specificity of the protective CD8+ T cell remain unknown. The aim of this study was to identify C. pneumoniae-derived mouse CD8 epitopes by using a recent epitope prediction method. Of four C. pneumoniae proteins (the major outer membrane protein, outer membrane protein 2, polymorphic outer membrane protein 5, and heat shock protein 60), 53 potential CD8+ T-cell epitopes were predicted by H-2 class I binding algorithms. Nineteen of the 53 peptides were identified as CD8 epitopes by testing for induction of a cytotoxic response after immunization. To test whether the predicted epitopes are naturally processed and presented by C. pneumoniae-infected cells, we generated a panel of seven peptide-specific cytotoxic T lymphocyte lines that were subsequently tested for recognition of C. pneumoniae-infected target cells. By using this strategy, we were able to identify three C. pneumoniae CD8 epitopes that were, indeed, processed and presented on infected cells. Identification of these natural CD8 epitopes provides tools for characterization of CD8+ T-cell function in vivo and generation of epitope-specific prevention strategies.

scholarly journals Garage Demos: Using Physical Models to Illustrate Dynamic Aspects of Microscopic Biological Processes

2009 ◽  
Vol 8 (2) ◽  
pp. 118-122 ◽  
Author(s):  
Diane K. O'Dowd ◽  
Nancy Aguilar-Roca
Keyword(s):  
Cell Biology ◽  
Physical Models ◽  
Lecture Hall ◽  
Biological Processes ◽  
Standard Format ◽  
Course Content ◽  
Faculty Interaction ◽  
Direct Measurements ◽  
Introductory Classes ◽  
Pipe Insulation

Colorful PowerPoint presentations with detailed drawings, micrographs, and short animations have become the standard format for illustrating the fundamental features of cell biology in large introductory classes. In this essay, we describe a low-tech tool that can be included in a standard lecture to help students visualize, understand, and remember the dynamic aspects of microscopic cell biological processes. This approach involves use of common objects, including pipe insulation and a garden hose, to illustrate basic processes such as protein folding and cloning, hence the appellation “garage demos.” The demonstrations are short, minimizing displacement of course content, easy to make, and provide an avenue for increasing student–faculty interaction in a large lecture hall. Student feedback over the past 4 years has been overwhelmingly positive. In an anonymous postclass survey in 2007, 90% of the respondents rated garage demos as having been very or somewhat helpful for understanding course concepts. Direct measurements of learning gains on specific concepts illustrated by garage demos are the focus of an ongoing study.

scholarly journals Outer membrane-deprived cyanobacteria liberate periplasmic and thylakoid luminal components that support the growth of heterotrophs

2020 ◽  
Author(s):  
Seiji Kojima ◽  
Yasuaki Okumura
Keyword(s):  
Host Cell ◽  
Outer Membrane ◽  
Cell Function ◽  
Heterotrophic Bacteria ◽  
Photosynthetic Electron Transport ◽  
Physical Interaction ◽  
Free Living ◽  
Chloroplast Evolution ◽  
Photosynthetic Products ◽  
Host Metabolism

ABSTRACTChloroplasts originate from endosymbiosis of a cyanobacterium within a heterotrophic host cell. Establishing endosymbiosis requires the translocation across its envelope of photosynthetic products generated inside the once free-living cyanobacterium to be exploited by host metabolism. However, the nature of this translocation event is unknown. We previously found that most cyanobacterial outer membrane components were eliminated during the primitive stage of chloroplast evolution, suggesting the importance of evolutionary changes of the outer membrane. Here, we removed the outer membrane from Synechocystis sp. PCC 6803 by disrupting the physical interaction with peptidoglycan, and characterized the effects on cell function. Outer membrane-deprived cells liberated diverse substances into the environment without significantly compromising photoautotrophic growth. The amount of liberated proteins increased to ~0.35 g/L within five days of culture. Proteomic analysis showed that most liberated proteins were periplasmic and thylakoid luminal components. Connectivity between the thylakoid lumen-extracellular space was confirmed by findings that an exogenous hydrophilic oxidant was reduced by photosynthetic electron transport chain on the thylakoid membrane. Metabolomic analysis detected the release of nucleotide-related metabolites at concentrations around 1 μM. The liberated materials supported the proliferation of heterotrophic bacteria. These findings show that breaching the outer membrane, without any manipulations to the cytoplasmic membrane, converts a cyanobacterium to a chloroplast-like organism that conducts photosynthesis and releases its biogenic materials. This conversion not only represents a potential explanation why the outer membrane markedly changed during the earliest stage of chloroplast evolution, but also provides the opportunity to harness cyanobacterial photosynthesis for biomanufacturing processes.SIGNIFICANCE STATEMENTAlthough it is well accepted that chloroplasts stem from endosymbiosis of a cyanobacterium within a heterotrophic host cell, the issue of how photosynthetic products generated inside a formerly free-living cyanobacterium are translocated across its envelope and exploited by host metabolism has been little addressed. Here we show that breaching the cyanobacterial outer membrane barrier converts a cyanobacterium to a chloroplast-like organism that conducts photosynthesis and releases its diverse biogenic materials into its external environment, which sustains the growth of heterotrophic organisms. This conversion represents a possible example of metabolic exploitation of cyanobacterial photosynthesis. Further, this “quasi-chloroplast” provides a potential opportunity for industrial application such as producing feedstock for biomanufacturing processes that harnesses heterotrophic bacteria.

scholarly journals TRAK proteins encode distinct MIRO-dependent and MIRO-independent mechanisms for associating with the mitochondrial outer membrane

2021 ◽  
Author(s):  
Lili Mitchell ◽  
Kathryn E. Reda ◽  
Hijab Fatima ◽  
Claudia E. Vasquez ◽  
Omar Alberto Quintero-Carmona
Keyword(s):  
Outer Membrane ◽  
Cell Function ◽  
Protein Localization ◽  
Adaptor Protein ◽  
Past Research ◽  
Small Gtpase ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Movement ◽  
C Terminus

Mitochondria are essential to proper cell function, mislocalization of mitochondria leads to disease. Previous research has indicated that MYO19, an unconventional myosin, localizes to the mitochondria outer membrane (MOM) and enables actin-based mitochondrial movement along the cytoskeleton. MOM insertion of MYO19 is assisted by the small GTPase MIRO, a "molecular switch" that facilitates MYO19/mitochondria interactions. MIRO serves as a recruiter of MYO19 to the MOM, rather than the tether/receptor that mediates attachment, as MYO19 contains a second, MIRO-independent mitochondrial association domain. MIRO proteins have previously been reported to serve as attachment points for the microtubule-based motors through interactions with the adaptor protein, TRAK. Past research has identified a MIRO-binding domain of TRAK that directly participates in the interaction with MIRO. We chose to investigate whether the interactions between TRAK and MOM paralleled our hypothesized mechanism for MYO19/MOM interactions by examining the MIRO-mediated enhancement of TRAK protein localization to mitochondria, by identifying the location of a MIRO-independent mitochondrial association domain in the c-terminus of TRAK proteins, and by examining the steady-state binding kinetics of various TRAK constructs to mitochondria. We interpret these data to indicate that MIRO proteins serve in the initial recruitment of TRAK proteins to mitochondria, but that the MIRO-independent domain plays a significant role in long-term association between TRAK and MOM.

scholarly journals Correlative nanophotonic approaches to enlighten the nanoscale dynamics of living cell membranes

2021 ◽  
Author(s):  
Pamina M. Winkler ◽  
María F. García-Parajo
Keyword(s):  
Extracellular Matrix ◽  
Cell Membrane ◽  
Actin Cytoskeleton ◽  
Single Molecule ◽  
Living Cell ◽  
Cell Membranes ◽  
Cell Function ◽  
Membrane Dynamics ◽  
Correlation Spectroscopy ◽  
Spatiotemporal Resolution

Dynamic compartmentalization is a prevailing principle regulating the spatiotemporal organization of the living cell membrane from the nano- up to the mesoscale. This non-arbitrary organization is intricately linked to cell function. On living cell membranes, dynamic domains or ‘membrane rafts' enriched with cholesterol, sphingolipids and other certain proteins exist at the nanoscale serving as signaling and sorting platforms. Moreover, it has been postulated that other local organizers of the cell membrane such as intrinsic protein interactions, the extracellular matrix and/or the actin cytoskeleton synergize with rafts to provide spatiotemporal hierarchy to the membrane. Elucidating the intricate coupling of multiple spatial and temporal scales requires the application of correlative techniques, with a particular need for simultaneous nanometer spatial precision and microsecond temporal resolution. Here, we review novel fluorescence-based techniques that readily allow to decode nanoscale membrane dynamics with unprecedented spatiotemporal resolution and single-molecule sensitivity. We particularly focus on correlative approaches from the field of nanophotonics. Notably, we introduce a versatile planar nanoantenna platform combined with fluorescence correlation spectroscopy to study spatiotemporal heterogeneities on living cell membranes at the nano- up to the mesoscale. Finally, we outline remaining future technological challenges and comment on potential directions to advance our understanding of cell membrane dynamics under the influence of the actin cytoskeleton and extracellular matrix in uttermost detail.

scholarly journals Answers to naysayers regarding microbial extracellular vesicles

2019 ◽  
Vol 47 (4) ◽  
pp. 1005-1012 ◽  
Author(s):  
Carolina Coelho ◽  
Arturo Casadevall
Keyword(s):  
Cell Wall ◽  
Extracellular Vesicles ◽  
Living Cell ◽  
Physiological Function ◽  
Biological Significance ◽  
Gram Negative Bacteria ◽  
Biological Processes ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

Abstract It is now over 30 years since the discovery of extracellular vesicles (EVs) in Gram-negative bacteria. However, for cell-walled microbes such as fungi, mycobacteria and Gram-positive bacteria it was thought that EV release would be impossible, since such structures were not believed to cross the thick cell wall. This notion was disproven 10 years ago with the discovery of EVs in fungi, mycobacteria, and gram-positive bacteria. Today, EVs have been described in practically every species tested, ranging from Fungi through Bacteria and Archaea, suggesting that EVs are a feature of every living cell. However, there continues to be skepticism in some quarters regarding EV release and their biological significance. In this review, we list doubts that have been verbalized to us and provide answers to counter them. In our opinion, there is no doubt as to existence and physiological function of EVs and we take this opportunity to highlight the most pressing topics in our understanding of the biological processes underlying these structures.

ZNF219 protects human lens epithelial cells against H2O2-induced injury via targeting SOX9 through activating AKT/GSK3β pathway

2021 ◽  
pp. 096032712110279
Author(s):  
Q Guo ◽  
Q Geletu ◽  
Y Zhang
Keyword(s):  
Oxidative Stress ◽  
Epithelial Cells ◽  
Cell Function ◽  
Oxidative Stress Response ◽  
Human Lens ◽  
Lens Epithelial Cells ◽  
Biological Processes ◽  
Urgent Problem ◽  
Human Lens Epithelial Cells ◽  
And Oxidative Stress

Opacity of the lens caused by cataracts could lead to severe visual impairment and even blindness. Oxidative stress caused by exposure of lens epithelial cells to hydrogen peroxide (H2O2) can lead to DNA damage and impair cell function. Therefore, how to prevent lens epithelial cells from being harmed by H2O2 is an urgent problem. The ZNF219 gene belongs to the Kruppel like zinc finger gene family, which is involved in a variety of biological processes. In this study, we found the low expression of ZNF219 in H2O2-induced HLE-B3 cells. We further noticed ZNF219 could improve the survival rate of H2O2-induced HLE-B3 cells, and inhibit the apoptosis and oxidative stress response. Mechanically, ZNF219 protected human lens epithelial cells against H2O2-induced injury via targeting SOX9 through activating AKT/GSK3β pathway. We therefore thought ZNF219 was a key protective protein in the oxidative damage of human lens epithelial cells and the pathogenesis of cataract.

Sign in / Sign up

Export Citation Format

Share Document