Mechanisms of Initiation of Membrane Fusion: Role of Lipids

2000 ◽  
Vol 20 (6) ◽  
pp. 465-482 ◽  
Author(s):  
Paavo K. J. Kinnunen ◽  
Juha M. Holopainen
Keyword(s):  
Membrane Fusion ◽  
Lipid Bilayers ◽  
Molecular Level ◽  
Cellular Processes ◽  
Lamellar Phases ◽  
Main Emphasis ◽  
Wide Range ◽  
Lipid Conformation ◽  
Level Fusion

Main emphasis in studies on the mechanisms of fusion of cellular membranes has been in the roles of various proteins, with far less interest in the properties of lipids. Yet, on a molecular level fusion involves the merging of lipid bilayers. Studies so far have revealed lipids forming inverted non-lamellar phases to be important in controlling membrane fusion. However, the underlying molecular level mechanisms have remained controversial. While this review is focused on presenting one possible mechanism, involving so-called extended lipid conformation, we are also advocating the view, that in order to obtain a more complete understanding of this process it is necessary to merge the relevant physicochemical properties of lipids with the models describing the specific functions of proteins. To this end, taking into account the central importance of fusion in a wide range of cellular processes, we may anticipate its control to open novel possibilities also for therapeutic intervention.

scholarly journals Subinhibitory Antimicrobial Concentrations: A Review of In Vitro and In Vivo Data

1992 ◽  
Vol 3 (4) ◽  
pp. 193-201 ◽  
Author(s):  
George G Zhanel ◽  
Daryl J Hoban ◽  
Godfrey KM Harding
Keyword(s):  
Antimicrobial Activity ◽  
Animal Studies ◽  
Molecular Level ◽  
Bacterial Virulence ◽  
Antibacterial Effects ◽  
Wide Range ◽  
Immune Defences

Antimicrobial activity is not an ‘all or none’ effect. An increase in the rate and extent of antimicrobial action is usually observed over a wide range of antimicrobial concentrations. Subinhibitory antimicrobial concentrations are well known to produce significant antibacterial effects, and various antimicrobials at subinhibitory concentrations have been reported to inhibit the rate of bacterial growth. Bacterial virulence may be increased or decreased by subinhibitory antimicrobial concentrations by changes in the ability of bacteria to adhere to epithelial cells or by alterations in bacterial susceptibility to host immune defences. Animal studies performed in rats, hamsters and rabbits demonstrate decreased bacterial adherence, reduced infectivity and increased survival of animals treated with subinhibitory antimicrobial concentrations compared to untreated controls. The major future role of investigation of subinhibitory antimicrobial concentrations will be to define more fully, at a molecular level, how antimicrobials exert their antibacterial effects.

scholarly journals Autophagy is activated in the ovarian tissue of polycystic ovary syndrome

Reproduction ◽  
2018 ◽  
Vol 155 (1) ◽  
pp. 85-92 ◽  
Author(s):  
Da Li ◽  
Yue You ◽  
Fang-Fang Bi ◽  
Tie-Ning Zhang ◽  
Jiao Jiao ◽  
...  
Keyword(s):  
Polycystic Ovary Syndrome ◽  
Potential Role ◽  
Polycystic Ovary ◽  
Ovarian Tissue ◽  
Ovary Syndrome ◽  
Cellular Processes ◽  
Transmission Electron ◽  
Wide Range ◽  
Response To Stress

The importance of autophagy in polycystic ovary syndrome (PCOS)-related metabolic disorders is increasingly being recognized, but few studies have investigated the role of autophagy in PCOS. Here, transmission electron microscopy demonstrated that autophagy was enhanced in the ovarian tissue from both humans and rats with PCOS. Consistent with this, ovarian granulosa cells from PCOS rats showed increases in the autophagy marker protein light chain 3B (LC3B), whereas levels of the autophagy substrate SQSTM1/p62 were decreased. In addition, the ratio of LC3-II/LC3-I was markedly elevated in human PCOS ovarian tissue compared with normal ovarian tissue. Real-time PCR arrays indicated that 7 and 34 autophagy-related genes were down- and up-regulated in human PCOS , Signal-Net, and regression analysis suggested that there are a wide range of interactions among these 41 genes, and a potential network based on EGFR, ERBB2, FOXO1, MAPK1, NFKB1, IGF1, TP53 and MAPK9 may be responsible for autophagy activation in PCOS. Systematic functional analysis of 41 differential autophagy-related genes indicated that these genes are highly involved in specific cellular processes such as response to stress and stimulus, and are linked to four significant pathways, including the insulin, ERBB, mTOR signaling pathways and protein processing in the endoplasmic reticulum. This study provides evidence for a potential role of autophagy disorders in PCOS in which autophagy may be an important molecular event in the pathogenesis of PCOS.

scholarly journals Understanding the Unique Role of Phospholipids in the Lubrication of Natural Joints: An Interfacial Tension Study

Coatings ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 264 ◽  
Author(s):  
Aneta D. Petelska ◽  
Katarzyna Kazimierska-Drobny ◽  
Katarzyna Janicka ◽  
Tomasz Majewski ◽  
Wiesław Urbaniak
Keyword(s):  
Interfacial Tension ◽  
Lipid Bilayers ◽  
Solid Lubricant ◽  
Solid Lubricants ◽  
Phospholipid Bilayer ◽  
Low Friction ◽  
Unique Role ◽  
Lamellar Phases ◽  
Chemical Inertness

Some solid lubricants are characterized by a layered structure with weak (van der Waals) inter-interlayer forces which allow for easy, low-strength shearing. Solid lubricants in natural lubrication are characterized by phospholipid bilayers in the articular joints and phospholipid lamellar phases in synovial fluid. The influence of the acid–base properties of the phospholipid bilayer on the wettability and properties of the surface have been explained by studying the interfacial tension of spherical lipid bilayers based on a model membrane. In this paper, we show that the phospholipid multi-bilayer can act as an effective solid lubricant in every aspect, ranging from a ‘corrosion inhibitor’ in the stomach to a load-bearing lubricant in bovine joints. We present evidence of the outstanding performance of phospholipids and argue that this is due to their chemical inertness and hydrophilic–hydrophobic structure, which makes them amphoteric and provides them with the ability to form lamellar structures that can facilitate functional sliding. Moreover, the friction coefficient can significantly change for a given phospholipid bilayer so it leads to a lamellar-repulsive mechanism under highly charged conditions. After this, it is quickly transformed to result in stable low-friction conditions.

Molecular mechanisms of endolysosomal Ca2+ signalling in health and disease

2011 ◽  
Vol 439 (3) ◽  
pp. 349-378 ◽  
Author(s):  
Anthony J. Morgan ◽  
Frances M. Platt ◽  
Emyr Lloyd-Evans ◽  
Antony Galione
Keyword(s):  
Molecular Mechanisms ◽  
Cellular Processes ◽  
Late Endosomes ◽  
Wide Range ◽  
Health And Disease ◽  
Lysosome Related Organelles ◽  
Cellular Compartments ◽  
Endosomal Vesicles ◽  
Intracellular Targets

Endosomes, lysosomes and lysosome-related organelles are emerging as important Ca2+ storage cellular compartments with a central role in intracellular Ca2+ signalling. Endocytosis at the plasma membrane forms endosomal vesicles which mature to late endosomes and culminate in lysosomal biogenesis. During this process, acquisition of different ion channels and transporters progressively changes the endolysosomal luminal ionic environment (e.g. pH and Ca2+) to regulate enzyme activities, membrane fusion/fission and organellar ion fluxes, and defects in these can result in disease. In the present review we focus on the physiology of the inter-related transport mechanisms of Ca2+ and H+ across endolysosomal membranes. In particular, we discuss the role of the Ca2+-mobilizing messenger NAADP (nicotinic acid adenine dinucleotide phosphate) as a major regulator of Ca2+ release from endolysosomes, and the recent discovery of an endolysosomal channel family, the TPCs (two-pore channels), as its principal intracellular targets. Recent molecular studies of endolysosomal Ca2+ physiology and its regulation by NAADP-gated TPCs are providing exciting new insights into the mechanisms of Ca2+-signal initiation that control a wide range of cellular processes and play a role in disease. These developments underscore a new central role for the endolysosomal system in cellular Ca2+ regulation and signalling.

Protein Fibrillar Nanopolymers: Molecular-Level Insights into Their Structural, Physical and Mechanical Properties

2015 ◽  
Vol 10 (03) ◽  
pp. 135-156 ◽  
Author(s):  
Valeriya M. Trusova
Keyword(s):  
Protein Misfolding ◽  
Amyloid Fibrils ◽  
Molecular Level ◽  
Physical And Mechanical Properties ◽  
Present Contribution ◽  
Wide Range ◽  
Generic Class ◽  
Protein Fibril

Amyloid fibrils represent a generic class of mechanically strong and stable biomaterials with extremely advantageous properties. Although amyloids were initially associated only with severe neurological disorders, the role of these structures nowadays is shifting from health debilitating to highly beneficial both in biomedical and technological aspects. Intensive involvement of fibrillar assemblies into the wide range of pathogenic and functional processes strongly necessitate the molecular level characterization of the structural, physical and elastic features of protein nanofibrils. In the present contribution, we made an attempt to highlight the up-to-date progress in the understanding of amyloid properties from the polymer physics standpoint. The fundamental insights into protein fibril behavior are essential not only for development of therapeutic strategies to combat the protein misfolding disorders but also for rational and precise design of novel biodegradable protein-based nanopolymers.

scholarly journals The Golgi apparatus in neurorestoration

2019 ◽  
Vol 7 (3) ◽  
pp. 116-128
Author(s):  
Jianyang Liu ◽  
Jialin He ◽  
Yan Huang ◽  
Han Xiao ◽  
Zheng Jiang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Golgi Apparatus ◽  
Neurodegenerative Diseases ◽  
Disease Progression ◽  
Neurological Recovery ◽  
Cellular Processes ◽  
Wide Range ◽  
And Oxidative Stress

The central role of the Golgi apparatus in critical cellular processes such as the transport, processing, and sorting of proteins and lipids has placed it at the forefront of cell science. Golgi apparatus dysfunction caused by primary defects within the Golgi or pharmacological and oxidative stress has been implicated in a wide range of neurodegenerative diseases. In addition to participating in disease progression, the Golgi apparatus plays pivotal roles in angiogenesis, neurogenesis, and synaptogenesis, thereby promoting neurological recovery. In this review, we focus on the functions of the Golgi apparatus and its mediated events during neurorestoration.

scholarly journals Muscling in on mitochondrial sexual dimorphism; role of mitochondrial dimorphism in skeletal muscle health and disease

2017 ◽  
Vol 131 (15) ◽  
pp. 1919-1922 ◽  
Author(s):  
Gareth A. Nye ◽  
Giorgos K. Sakellariou ◽  
Hans Degens ◽  
Adam P. Lightfoot
Keyword(s):  
Skeletal Muscle ◽  
Sexual Dimorphism ◽  
Mitochondrial Function ◽  
Recent Article ◽  
Cellular Processes ◽  
Wide Range ◽  
Health And Disease ◽  
Muscle Health ◽  
The Impact

Mitochondria are no longer solely regarded as the cellular powerhouse; instead, they are now implicated in mediating a wide-range of cellular processes, in the context of health and disease. A recent article in Clinical Science, Ventura-Clapier et al. highlights the role of sexual dimorphism in mitochondrial function in health and disease. However, we feel the authors have overlooked arguably one of the most mitochondria-rich organs in skeletal muscle. Many studies have demonstrated that mitochondria have a central role in mediating the pathogenesis of myopathologies. However, the impact of sexual dimorphism in this context is less clear, with several studies reporting conflicting observations. For instance in ageing studies, a rodent model reported female muscles have higher antioxidant capacity compared with males; in contrast, human studies demonstrate no sex difference in mitochondrial bioenergetics and oxidative damage. These divergent observations highlight the importance of considering models and methods used to examine mitochondrial function, when interpreting these data. The use of either isolated or intact mitochondrial preparations in many studies appears likely to be a source of discord, when comparing many studies. Overall, it is now clear that more research is needed to determine if sexual dimorphism is a contributing factor in the development of myopathologies.

scholarly journals Interaction of the Hippo Pathway and Phosphatases in Tumorigenesis

Cancers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2438 ◽  
Author(s):  
Sahar Sarmasti Emami ◽  
Derek Zhang ◽  
Xiaolong Yang
Keyword(s):  
Signaling Pathway ◽  
Hippo Pathway ◽  
Underlying Mechanism ◽  
Hippo Signaling ◽  
Hippo Signaling Pathway ◽  
Cellular Processes ◽  
Wide Range ◽  
Future Direction ◽  
The Hippo Pathway

The Hippo pathway is an emerging tumor suppressor signaling pathway involved in a wide range of cellular processes. Dysregulation of different components of the Hippo signaling pathway is associated with a number of diseases including cancer. Therefore, identification of the Hippo pathway regulators and the underlying mechanism of its regulation may be useful to uncover new therapeutics for cancer therapy. The Hippo signaling pathway includes a set of kinases that phosphorylate different proteins in order to phosphorylate and inactivate its main downstream effectors, YAP and TAZ. Thus, modulating phosphorylation and dephosphorylation of the Hippo components by kinases and phosphatases play critical roles in the regulation of the signaling pathway. While information regarding kinase regulation of the Hippo pathway is abundant, the role of phosphatases in regulating this pathway is just beginning to be understood. In this review, we summarize the most recent reports on the interaction of phosphatases and the Hippo pathway in tumorigenesis. We have also introduced challenges in clarifying the role of phosphatases in the Hippo pathway and future direction of crosstalk between phosphatases and the Hippo pathway.

scholarly journals Long Noncoding RNA SOX2-OT Exacerbates Hypoxia-Induced Cardiomyocytes Injury by Regulating miR-27a-3p/TGFβR1 Axis

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Guang Yang ◽  
Chunsheng Lin
Keyword(s):  
Heart Failure ◽  
Cell Apoptosis ◽  
Long Noncoding Rna ◽  
Noncoding Rna ◽  
Heart Diseases ◽  
Luciferase Reporter ◽  
Migration And Invasion ◽  
Cellular Processes ◽  
Wide Range

Background. Myocardial infarction (MI) was a severe cardiovascular disease resulted from acute, persistent hypoxia, or ischemia condition. Additionally, MI generally led to heart failure, even sudden death. A multitude of research studies proposed that long noncoding RNAs (lncRNAs) frequently participated in the regulation of heart diseases. The specific function and molecular mechanism of SOX2-OT in MI remained unclear. Aim of the Study. The current research was aimed to explore the role of SOX2-OT in MI. Methods. Bioinformatics analysis (DIANA tools and Targetscan) and a wide range of experiments (CCK-8, flow cytometry, RT-qPCR, luciferase reporter, RIP, caspase-3 activity, trans-well, and western blot assays) were adopted to investigate the function and mechanism of SOX2-OT. Results. We discovered that hypoxia treatment decreased cell viability but increased cell apoptosis. Besides, lncRNA SOX2-OT expression was upregulated in hypoxic HCMs. Hereafter, we confirmed that SOX2-OT could negatively regulate miR-27a-3p levels by directly binding with miR-27a-3p, and miR-27a-3p also could negatively regulate SOX2-OT levels. Furthermore, knockdown of SOX2-OT promoted cell proliferation, migration, and invasion, but limited cell apoptosis. However, these effects were reversed by anti-miR-27a-5p. Besides, we verified that miR-27a-3p binding with the 3′UTR of TGFBR1 and SOX2-OT regulated TGFβR1 level by collaborating with miR-27a-3p in HCMs. Eventually, rescue assays validated that the influence of SOX2-OT silence or miR-27a-3p overexpression on cellular processes in cardiomyocytes injury was counteracted by TGFBR1 overexpression. Conclusions. Long noncoding RNA SOX2-OT exacerbated hypoxia-induced cardiomyocytes injury by regulating miR-27a-3p/TGFβR1 axis, which may provide a novel insight for heart failure treatment.

scholarly journals Single-molecule FRET study of SNARE-mediated membrane fusion

2011 ◽  
Vol 31 (6) ◽  
pp. 457-463 ◽  
Author(s):  
Jiajie Diao ◽  
Yuji Ishitsuka ◽  
Woo-Ri Bae
Keyword(s):  
Membrane Fusion ◽  
Lipid Bilayers ◽  
Single Molecule ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Cellular Processes ◽  
Single Molecule Fret ◽  
Protein Receptor ◽  
Hydrophobic Cores

Membrane fusion is one of the most important cellular processes by which two initially distinct lipid bilayers merge their hydrophobic cores, resulting in one interconnected structure. Proteins, called SNARE (soluble N-ethylmaleimide-sensitive factor-attachment protein receptor), play a central role in the fusion process that is also regulated by several accessory proteins. In order to study the SNARE-mediated membrane fusion, the in vitro protein reconstitution assay involving ensemble FRET (fluorescence resonance energy transfer) has been used over a decade. In this mini-review, we describe several single-molecule-based FRET approaches that have been applied to this field to overcome the shortage of the bulk assay in terms of protein and fusion dynamics.

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