Preservation of Supported Lipid Membrane Integrity from Thermal Disruption: Osmotic Effect

2016 ◽  
Vol 8 (9) ◽  
pp. 5857-5866
Author(s):  
Tao Zhu ◽  
Zhongying Jiang ◽  
Yuqiang Ma ◽  
Yong Hu
Keyword(s):  
Lipid Membrane ◽  
Membrane Integrity ◽  
Osmotic Effect

scholarly journals The interplay between lipids and dopamine on α-synuclein oligomerization and membrane binding

2013 ◽  
Vol 33 (5) ◽  
Author(s):  
Chi L. L. Pham ◽  
Roberto Cappai
Keyword(s):  
Lipid Membranes ◽  
Amyloid Fibrils ◽  
Lipid Membrane ◽  
Hydrophobic Interactions ◽  
Membrane Integrity ◽  
Lipid Vesicles ◽  
Helical Conformation ◽  
Unfolded Protein ◽  
Natively Unfolded Protein ◽  
Natively Unfolded

The deposition of α-syn (α-synuclein) as amyloid fibrils and the selective loss of DA (dopamine) containing neurons in the substantia nigra are two key features of PD (Parkinson's disease). α-syn is a natively unfolded protein and adopts an α-helical conformation upon binding to lipid membrane. Oligomeric species of α-syn have been proposed to be the pathogenic species associated with PD because they can bind lipid membranes and disrupt membrane integrity. DA is readily oxidized to generate reactive intermediates and ROS (reactive oxygen species) and in the presence of DA, α-syn form of SDS-resistant soluble oligomers. It is postulated that the formation of the α-syn:DA oligomers involves the cross-linking of DA-melanin with α-syn, via covalent linkage, hydrogen and hydrophobic interactions. We investigate the effect of lipids on DA-induced α-syn oligomerization and studied the ability of α-syn:DA oligomers to interact with lipids vesicles. Our results show that the interaction of α-syn with lipids inhibits the formation of DA-induced α-syn oligomers. Moreover, the α-syn:DA oligomer cannot interact with lipid vesicles or cause membrane permeability. Thus, the formation of α-syn:DA oligomers may alter the actions of α-syn which require membrane association, leading to disruption of its normal cellular function.

scholarly journals Polyglutamine aggregates impair lipid membrane integrity and enhance lipid membrane rigidity

2016 ◽  
Vol 1858 (4) ◽  
pp. 661-670 ◽  
Author(s):  
Chian Sing Ho ◽  
Nawal K. Khadka ◽  
Fengyu She ◽  
Jianfeng Cai ◽  
Jianjun Pan
Keyword(s):  
Lipid Membrane ◽  
Membrane Integrity ◽  
Membrane Rigidity

Effects of Various Solutes on the Thermostability of Isocitrate Dehydrogenase and Malate Dehydrogenase of Isolated Plant Mitochondria.

1982 ◽  
Vol 9 (6) ◽  
pp. 715 ◽  
Author(s):  
D Nash ◽  
JT Wiskich
Keyword(s):  
Malate Dehydrogenase ◽  
Isocitrate Dehydrogenase ◽  
Choline Chloride ◽  
Plant Mitochondria ◽  
Membrane Integrity ◽  
Triticum Aestivum L ◽  
Osmotic Effect ◽  
Pisum Sativum L ◽  
Wheat Leaves ◽  
Brassica Oleracea L

Proline and betaine increased the thermostability of NAD-isocitrate dehydrogenase (EC 1.1.1.41) and of NAD-malate dehydrogenase (EC 1.1.1.37) when mitochondria isolated from pea leaves (Pisum sativum L.), wheat leaves (Triticum aestivum L.) and cauliflower buds (Brassica oleracea L.) were heated. Potassium chloride and choline chloride also increased the thermostability of isocitrate dehydrogenase in the three species, but their effects on malate dehydrogenase varied. Protection was found with both intact and disrupted mitochondria, indicating that it was not dependent on an osmotic effect. Proline and KCl also prolonged membrane integrity, as measured by impermeability to NAD+, during heating of pea leaf and cauliflower bud mitochondria. Phenylalanine reduced the thermostability of isocitrate dehydrogenase, indicating that protection is not a general solute effect.

scholarly journals Osmotic stress and cryoinjury of koala sperm: an integrative study of the plasma membrane, chromatin stability and mitochondrial function

Reproduction ◽  
2012 ◽  
Vol 143 (6) ◽  
pp. 787-797 ◽  
Author(s):  
S D Johnston ◽  
N Satake ◽  
Y Zee ◽  
C López-Fernández ◽  
W V Holt ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Dna Fragmentation ◽  
Structural Damage ◽  
Membrane Integrity ◽  
Integrative Model ◽  
Sperm Dna Fragmentation ◽  
Hypertonic Stress ◽  
Osmotic Effect ◽  
Sperm Nuclei ◽  
Severe Degree

This study investigated whether cryopreservation-induced injury to koala spermatozoa could be explained using an experimental model that mimics the structural and physiological effects of osmotic flux. DNA labelling after in situ nick translation of thawed cryopreserved spermatozoa revealed a positive correlation (r=0.573; P<0.001; n=50) between the area of relaxed chromatin in the nucleus and the degree of nucleotide labelling. While the chromatin of some spermatozoa increased more than eight times its normal size, not all sperm nuclei with relaxed chromatin showed evidence of nucleotide incorporation. Preferential staining associated with sperm DNA fragmentation (SDF) was typically located in the peri-acrosomal and peripheral regions of the sperm head and at the base of the spermatozoa where it appear to be ‘hot spots’ of DNA damage following cryopreservation. Results of the comparative effects of anisotonic media and cryopreservation on the integrity of koala spermatozoa revealed that injury induced by exposure to osmotic flux, essentially imitated the results found following cryopreservation. Plasma membrane integrity, chromatin relaxation and SDF appeared particularly susceptible to extreme hypotonic environments. Mitochondrial membrane potential (MMP), while susceptible to extreme hypo- and hypertonic environments, showed an ability to rebound from hypertonic stress when returned to isotonic conditions. Koala spermatozoa exposed to 64 mOsm/kg media showed an equivalent, or more severe, degree of structural and physiological injury to that of frozen–thawed spermatozoa, supporting the hypothesis that cryoinjury is principally associated with a hypo-osmotic effect. A direct comparison of SDF of thawed cryopreserved spermatozoa and those exposed to a 64 mOsm/kg excursion showed a significant correlation (r=0.878; P<0.05; n=5); however, no correlation was found when the percentage of sperm with relaxed chromatin was compared. While a cryo-induced osmotic injury model appears to explain post-thaw changes in koala SDF, the mechanisms resulting in relaxed chromatin require further study. A lack of correlation between the percentage of sperm with relaxed chromatin and SDF suggests that the timing of these pathologies are asynchronous. We propose an integrative model of cryo-induced osmotic injury that involves a combination of structural damage (rupture of membrane) and oxidative stress that first leads to the reduction of MMP and the relaxation of chromatin, which is then ultimately followed by an increase in DNA fragmentation.

scholarly journals 1-Deoxysphingolipids Tempt Autophagy Resulting in Lysosomal Lipid Substrate Accumulation: Tracing the Impact of 1-Deoxysphingolipids on Ultra-Structural Level using a Novel Click-Chemistry Detection

2021 ◽  
Author(s):  
Christian Lamberz ◽  
Marina Hesse ◽  
Gregor Kirfel
Keyword(s):  
Energy Homeostasis ◽  
Lipid Membrane ◽  
Membrane Damage ◽  
Membrane Integrity ◽  
Membrane Dynamics ◽  
Autophagic Flux ◽  
Structural Level ◽  
Cellular Energy ◽  
The Impact ◽  
Lipid Substrate

SUMMARYSphingolipids (SLs) are pivotal components of biological membranes essentially contributing to their physiological functions. 1-deoxysphingolipids (deoxySLs), an atypical cytotoxic acting sub-class of SLs, is relevant for cellular energy homeostasis and is known to be connected to neurodegenerative disorders including diabetic neuropathy and hereditary sensory neuropathy type 1 (HSAN1). High levels of deoxySLs affect lipid membrane integrity in artificial liposomes. Accordingly, recent reports questioned the impact of deoxySLs on physiological lipid membrane and organelle functions leading to impaired cellular energy homeostasis.However, DeoxySL-related structural effects on cell membranes resulting in organelle dysfunction are still obscure. To illuminate disease-relevant sub-cellular targets of deoxySLs, we traced alkyne-containing 1-deoxysphinganine (alkyne-DOXSA) and resulting metabolites on ultra-structural level using a new labeling approach for electron microscopy (EM) termed “Golden-Click-Method” (GCM). To complement high-resolution analysis with membrane dynamics, selected intracellular compartments were traced using fluorescent live dyes.Our results conclusively linked accumulating cytotoxic deoxySLs with mitochondria and endoplasmic reticulum (ER) damage triggering Autophagy of mitochondria and membrane cisterna of the ER. The induced autophagic flux ultimately leads to accumulating deoxySL containing intra-lysosomal lipid crystals. Lysosomal lipid substrate accumulation impaired physiological lysosome functions and caused cellular starvation. Lysosomal exocytosis appeared as a mechanism for cellular clearance of cytotoxic deoxySLs. In sum, our data define new ultra-structural targets of deoxySLs and link membrane damage to autophagy and abnormal lysosomal lipid accumulation. These insights may support new conclusions about diabetes type 2 and HSNA1 related tissue damage.

scholarly journals 3D-Visualization of Amyloid-β Oligomer and Fibril Interactions with Lipid Membranes by Cryo-Electron Tomography

2020 ◽  
Author(s):  
Yao Tian ◽  
Ruina Liang ◽  
Amit Kumar ◽  
Piotr Szwedziak ◽  
John H. Viles
Keyword(s):  
Lipid Bilayers ◽  
Molecular Mechanisms ◽  
Lipid Membrane ◽  
Electron Tomography ◽  
3D Visualization ◽  
Membrane Integrity ◽  
Amyloid Β ◽  
Lipid Vesicles ◽  
Aβ Oligomers ◽  
Cryo Electron Tomography

ABSTRACTAmyloid-β (Aβ) monomers assemble into mature fibrils via a range of metastable oligomeric and protofibrillar intermediates. These Aβ assemblies have been shown to bind to lipid bilayers. This can disrupt membrane integrity and cause a loss of cellular homeostasis, that triggers a cascade of events leading to Alzheimer’s disease. However, molecular mechanisms of Aβ cytotoxicity and how the different assembly forms interact with the membrane remain enigmatic. Here we use cryo-electron tomography (cryoET) to obtain three-dimensional nano-scale images of various Aβ assembly types and their interaction with liposomes. Aβ oligomers bind extensively to the lipid vesicles, inserting and carpeting the upper-leaflet of the bilayer. Furthermore, curvilinear protofibrils also insert into the bilayer, orthogonally to the membrane surface. Aβ oligomers concentrate at the interface of vesicles and form a network of Aβ-linked liposomes. While crucially, monomeric and fibrillar Aβ have relatively little impact on the membrane. Changes to lipid membrane composition highlights a significant role for GM1-ganglioside in promoting Aβ-membrane interactions. The different effects of Aβ assembly forms observed align with the highlighted cytotoxicity reported for Aβ oligomers. The wide-scale incorporation of Aβ oligomers and curvilinear protofibrils into the lipid bilayer suggests a mechanism by which membrane integrity is lost.

scholarly journals Development of Biocompatible Polymers for Modulating Lipid Membrane Integrity

2012 ◽  
Vol 102 (3) ◽  
pp. 496a
Author(s):  
Jia-Yu Wang ◽  
Brent Hammer ◽  
Phullara Shelat ◽  
Jeremy Marks ◽  
Todd Emrick ◽  
...  
Keyword(s):  
Lipid Membrane ◽  
Membrane Integrity ◽  
Biocompatible Polymers

scholarly journals The bacterial magnesium transporter MgtA reveals highly selective interaction with specific cardiolipin species

2021 ◽  
Author(s):  
Julia Weikum ◽  
Jeroen Vandyck ◽  
Saranya Subramani ◽  
David P Klebl ◽  
Merete Storflor ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Bacterial Infections ◽  
Lipid Membrane ◽  
Cell Structure ◽  
Acyl Chain ◽  
Ion Homeostasis ◽  
Membrane Integrity ◽  
E Coli ◽  
Lipid Species ◽  
Magnesium Transporter

A significant challenge today within protein lipidology is to understand the relationship between cell structure, lipid membrane integrity, ion homeostasis and the embedded membrane proteins. The bacterial magnesium transporter A (MgtA) is a specialized P-type ATPase important for Mg2+ import into the cytoplasm; disrupted magnesium homeostasis is linked to intrinsic ribosome instability and nitro-oxidative stress in Salmonella strains. MgtAs function is highly dependent on anionic lipids, particularly cardiolipin, and further co-localization of cardiolipin with MgtA at the E. coli cell poles has been revealed. Here, we show that MgtA has functional specificity for cardiolipin 18:1, but it reaches maximum activity only in combination with cardiolipin 16:0, equivalent to the major components of native cardiolipin found in E. coli membranes. This is the first time it has been shown experimentally that two different lipid species from the same class, individually promoting low activity, can enhance activity in combination. Native mass spectrometry verifies the presence of two binding sites for cardiolipin and kinetic studies reveal that a cooperative relationship likely exists between the two different cardiolipin variants (cardiolipin 16:0 and cardiolipin 18:1). This is the first experimental evidence of cooperative effects between lipids of the same class, with only minor variations in their acyl chain composition, acting on a membrane protein. In summary, our results reveal that MgtA exhibits a highly complex interaction with one cardiolipin 18:1 and one cardiolipin 16:0, affecting protein activity and stability, and contributing to our understanding of the particular interactions between lipid environment and membrane proteins. Further, a better understanding of Mg2+ homeostasis in bacteria, due to its role as a virulence regulator, will provide further insights into the regulation and mechanism of bacterial infections.

scholarly journals Bacillus thuringiensis Cyt2Aa2 toxin disrupts cell membranes by forming large protein aggregates

2016 ◽  
Vol 36 (5) ◽  
Author(s):  
Sudarat Tharad ◽  
José L. Toca-Herrera ◽  
Boonhiang Promdonkoy ◽  
Chartchai Krittanai
Keyword(s):  
Bacillus Thuringiensis ◽  
Cell Membranes ◽  
Lipid Membrane ◽  
Membrane Integrity ◽  
Protein Aggregates ◽  
Membrane Disruption ◽  
Large Protein

We show that the lipid membrane disruption by Bacillus thuringiensis (Bt) Cyt2Aa2 is different from the general pore-forming model. Cyt2Aa2 forms protein aggregates that disrupt the lipid membrane integrity.

scholarly journals Nanoprobes to interrogate nonspecific interactions in lipid bilayers: from defect-mediated adhesion to membrane disruption

2021 ◽  
Author(s):  
Giancarlo Rizza ◽  
Nicolò Razza ◽  
Alessio Lavino ◽  
Giulia Fadda ◽  
Lairez Didier ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membrane ◽  
Membrane Integrity ◽  
Membrane Disruption ◽  
Nonspecific Interactions

When a lipid membrane approaches a material/nanomaterial, nonspecific adhesion may occur. The interactions responsible for nonspecific adhesions can either preserve the membrane integrity or lead to its disruption. Despite the...

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