Interfacial Phases on Giant Unilamellar Vesicles

2012 ◽  
Author(s):  
Yanfei Jiang ◽  
Guy M. Genin ◽  
Srikanth Singamaneni ◽  
Elliot L. Elson
Keyword(s):  
Lipid Vesicles ◽  
Model System ◽  
Simplified Model ◽  
Membrane Rafts ◽  
Domain Formation ◽  
Enveloped Viruses ◽  
Cellular Processes ◽  
Pathological Conditions ◽  
Signaling Mechanisms ◽  
The Subject

Lipid nanodomains in cell membranes are believed to play a significant role in a number of critical cellular processes (Elson, et al., 2010). These include, for example, replication processes in enveloped viruses such as bird flu and HIV and signaling mechanisms underlying pathological conditions such as cancer. Due to the potential for developing new disease treatments through the control of these membrane rafts, the biophysics underlying their formation has been the subject of intense study, much of this focused on domain formation in giant unilamellar lipid vesicles (GUVs), a simplified model system.

Confidence Intervals for Estimation of the Concentration and Brightness of Multiple Diffusing Species

2012 ◽  
Author(s):  
Xi Rong ◽  
Kenneth M. Pryse ◽  
Jordan A. Whisler ◽  
Yanfei Jiang ◽  
William B. McConnaughey ◽  
...  
Keyword(s):  
Confidence Intervals ◽  
Significant Role ◽  
Fluorescence Correlation Spectroscopy ◽  
Correlation Spectroscopy ◽  
Membrane Rafts ◽  
Giant Unilamellar Vesicles ◽  
Enveloped Viruses ◽  
Fluorescence Correlation ◽  
Pathological Conditions ◽  
Signaling Mechanisms

Lipid nanodomains in cell membranes are believed to play a significant role in replication of enveloped viruses such as bird flu and HIV and signaling mechanisms underlying pathological conditions such as cancer. However, the forces that govern the formation and availability of these “membrane rafts” are uncertain, and even their existence is questioned. The central challenge is that no suitable imaging modalities exist (Elson, et al., 2010). We are developing tools to characterize and visualize dynamics of lipid nanodomains on idealized systems called giant unilamellar vesicles (GUVs) using fluorescence correlation spectroscopy (FCS) (Figure 1).

scholarly journals Membrane Rafts: Portals for Viral Entry

2021 ◽  
Vol 12 ◽  
Author(s):  
Inés Ripa ◽  
Sabina Andreu ◽  
José Antonio López-Guerrero ◽  
Raquel Bello-Morales
Keyword(s):  
Viral Entry ◽  
Relevant Information ◽  
Host Cells ◽  
Membrane Rafts ◽  
Enveloped Viruses ◽  
Virus Attachment ◽  
Cellular Processes ◽  
Entry Pathway ◽  
Cellular Factors

Membrane rafts are dynamic, small (10–200 nm) domains enriched with cholesterol and sphingolipids that compartmentalize cellular processes. Rafts participate in roles essential to the lifecycle of different viral families including virus entry, assembly and/or budding events. Rafts seem to participate in virus attachment and recruitment to the cell surface, as well as the endocytic and non-endocytic mechanisms some viruses use to enter host cells. In this review, we will introduce the specific role of rafts in viral entry and define cellular factors implied in the choice of one entry pathway over the others. Finally, we will summarize the most relevant information about raft participation in the entry process of enveloped and non-enveloped viruses.

scholarly journals Roles of Microglial Ion Channel in Neurodegenerative Diseases

2021 ◽  
Vol 10 (6) ◽  
pp. 1239
Author(s):  
Alexandru Cojocaru ◽  
Emilia Burada ◽  
Adrian-Tudor Bălșeanu ◽  
Alexandru-Florian Deftu ◽  
Bogdan Cătălin ◽  
...  
Keyword(s):  
Ion Channels ◽  
Neurodegenerative Diseases ◽  
Excitable Cells ◽  
Proton Channels ◽  
Voltage Gated ◽  
Cellular Processes ◽  
Pathological Conditions ◽  
The Common ◽  
Transient Receptor ◽  
The Impact

As the average age and life expectancy increases, the incidence of both acute and chronic central nervous system (CNS) pathologies will increase. Understanding mechanisms underlying neuroinflammation as the common feature of any neurodegenerative pathology, we can exploit the pharmacology of cell specific ion channels to improve the outcome of many CNS diseases. As the main cellular player of neuroinflammation, microglia play a central role in this process. Although microglia are considered non-excitable cells, they express a variety of ion channels under both physiological and pathological conditions that seem to be involved in a plethora of cellular processes. Here, we discuss the impact of modulating microglia voltage-gated, potential transient receptor, chloride and proton channels on microglial proliferation, migration, and phagocytosis in neurodegenerative diseases.

scholarly journals PRMT5-mediated arginine methylation activates AKT kinase to govern tumorigenesis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shasha Yin ◽  
Liu Liu ◽  
Charles Brobbey ◽  
Viswanathan Palanisamy ◽  
Lauren E. Ball ◽  
...  
Keyword(s):  
Kinase Activity ◽  
Arginine Methylation ◽  
Akt Signaling Pathway ◽  
Akt Inhibitor ◽  
Akt Kinase ◽  
Akt Activation ◽  
Cellular Processes ◽  
Pathological Conditions ◽  
Subsequent Activation ◽  
Oncogenic Function

AbstractAKT is involved in a number of key cellular processes including cell proliferation, apoptosis and metabolism. Hyperactivation of AKT is associated with many pathological conditions, particularly cancers. Emerging evidence indicates that arginine methylation is involved in modulating AKT signaling pathway. However, whether and how arginine methylation directly regulates AKT kinase activity remain unknown. Here we report that protein arginine methyltransferase 5 (PRMT5), but not other PRMTs, promotes AKT activation by catalyzing symmetric dimethylation of AKT1 at arginine 391 (R391). Mechanistically, AKT1-R391 methylation cooperates with phosphatidylinositol 3,4,5 trisphosphate (PIP3) to relieve the pleckstrin homology (PH)-in conformation, leading to AKT1 membrane translocation and subsequent activation by phosphoinositide-dependent kinase-1 (PDK1) and the mechanistic target of rapamycin complex 2 (mTORC2). As a result, deficiency in AKT1-R391 methylation significantly suppresses AKT1 kinase activity and tumorigenesis. Lastly, we show that PRMT5 inhibitor synergizes with AKT inhibitor or chemotherapeutic drugs to enhance cell death. Altogether, our study suggests that R391 methylation is an important step for AKT activation and its oncogenic function.

scholarly journals The complex of phosphatidylinositol 4,5-bisphosphate and calcium ions is not responsible for Ca(2+)-induced loss of phospholipid asymmetry in the human erythrocyte: a study in Scott syndrome, a disorder of calcium- induced phospholipid scrambling

Blood ◽  
1995 ◽  
Vol 86 (5) ◽  
pp. 1983-1991 ◽  
Author(s):  
EM Bevers ◽  
T Wiedmer ◽  
P Comfurius ◽  
J Zhao ◽  
EF Smeets ◽  
...  
Keyword(s):  
Lipid Vesicles ◽  
Human Erythrocytes ◽  
Mechanism Analysis ◽  
Membrane Phospholipids ◽  
Mole Percent ◽  
Cellular Processes ◽  
Phospholipid Asymmetry ◽  
Dependent Cell ◽  
Normal Human ◽  
State Concentration

Elevation of cytoplasmic Ca2+ levels in human erythrocytes induces a progressive loss of membrane phospholipid asymmetry, a process that is impaired in erythrocytes from a patient with Scott syndrome. We show here that porcine erythrocytes are similarly incapable of Ca(2+)- induced redistribution of membrane phospholipids. Because a complex of phosphatidylinositol 4,5-bisphosphate (PIP2) and Ca2+ has been proposed as the mediator of enhanced transbilayer movement of lipids (J Biol Chem 269:6347,1994), these cell systems offer a unique opportunity for testing this mechanism. Analysis of both total PIP2 content and the metabolic-resistant pool of PIP2 that remains after incubation with Ca2+ ionophore showed no appreciable differences between normal and Scott erythrocytes. Moreover, porcine erythrocytes were found to have slightly higher levels of both total and metabolic-resistant PIP2 in comparison with normal human erythrocytes. Although loading of normal erythrocytes with exogenously added PIP2 gave rise to a Ca(2+)-induced increase in prothrombinase activity and apparent transbilayer movement of nitrobenzoxadiazolyl (NBD)-phospholipids, these PIP2-loaded cells were also found to undergo progressive Ca(2+)-dependent cell lysis, which seriously hampers interpretation of these data. Moreover, loading Scott cells with PIP2 did not abolish their impaired lipid scrambling, even in the presence of a Ca(2+)-ionophore. Finally, artificial lipid vesicles containing no PIP2 or 1 mole percent of PIP2 were indistinguishable with respect to transbilayer movement of NBD- phosphatidylcholine in the presence of Ca2+. Our findings suggest that Ca(2+)-induced redistribution of membrane phospholipids cannot simply be attributed to the steady-state concentration of PIP2, and imply that such lipid movement is regulated by other cellular processes.

scholarly journals The Role of Prokineticin 2 in Oxidative Stress and in Neuropathological Processes

2021 ◽  
Vol 12 ◽  
Author(s):  
Roberta Lattanzi ◽  
Cinzia Severini ◽  
Daniela Maftei ◽  
Luciano Saso ◽  
Aldo Badiani
Keyword(s):  
Pain Perception ◽  
G Protein Coupled Receptors ◽  
Cellular Processes ◽  
Prokineticin 2 ◽  
Physiological Processes ◽  
Pathological Conditions ◽  
Double Function ◽  
The Central Nervous System ◽  
G Protein Coupled

The prokineticin (PK) family, prokineticin 1 and Bv8/prokineticin 2 (PROK2), initially discovered as regulators of gastrointestinal motility, interacts with two G protein-coupled receptors, PKR1 and PKR2, regulating important biological functions such as circadian rhythms, metabolism, angiogenesis, neurogenesis, muscle contractility, hematopoiesis, immune response, reproduction and pain perception. PROK2 and PK receptors, in particular PKR2, are widespread distributed in the central nervous system, in both neurons and glial cells. The PROK2 expression levels can be increased by a series of pathological insults, such as hypoxia, reactive oxygen species, beta amyloid and excitotoxic glutamate. This suggests that the PK system, participating in different cellular processes that cause neuronal death, can be a key mediator in neurological/neurodegenerative diseases. While many PROK2/PKRs effects in physiological processes have been documented, their role in neuropathological conditions is not fully clarified, since PROK2 can have a double function in the mechanisms underlying to neurodegeneration or neuroprotection. Here, we briefly outline the latest findings on the modulation of PROK2 and its cognate receptors following different pathological insults, providing information about their opposite neurotoxic and neuroprotective role in different pathological conditions.

scholarly journals Children of Heaven

2019 ◽  
Vol 5 (2) ◽  
Author(s):  
Olenka Kawchuk
Keyword(s):  
Low Temperature ◽  
South America ◽  
Geographic Origin ◽  
High Elevation ◽  
Human Sacrifice ◽  
Inca Empire ◽  
Pathological Conditions ◽  
The World ◽  
The Subject ◽  
Ritual Process

Ruling over western South America for nearly 100 years, the Inca Empire was one of many global cultures that practiced human sacrifice, though few other rituals of human sacrifice are as captivating as the Inca child sacrifice of capacocha. Capacocha children were chosen to be representatives of the Inca people in the afterlife. As such, they were afforded an elevated position in society before their death. Following their selection, children would undergo a year-long pilgrimage terminating at a mountain top shrine where they would be killed. As a result of the low temperature and oxygen levels present at such a high elevation, the bodies of capacocha children were protected against decomposition, creating some of the best-preserved natural mummies in the world. These mummies have been the subject of numerous bioarchaeological analyses to determine their age, sex, geographic origin, pathological conditions, diet, and cause of death. Beyond these, however, the mummies present a unique opportunity to study how the capacocha ritual process — including the sudden ascension in status — manifested itself on the children's bodies. This paper aims to review the bioarchaeological data garnered from the mummies in order to reconstruct the experience of a child chosen for capacocha. Results suggest higher variability between children selected for capacocha than was originally outlined by Spanish chroniclers.

scholarly journals Teaching a biology laboratory course using Dictyostelium

2019 ◽  
Vol 63 (8-9-10) ◽  
pp. 551-561
Author(s):  
David A. Knecht ◽  
Kate M. Cooper ◽  
Jonathan E. Moore
Keyword(s):  
Dictyostelium Discoideum ◽  
Cell Biology ◽  
Room Temperature ◽  
Model System ◽  
Educational Settings ◽  
Biology Teaching ◽  
Laboratory Course ◽  
Cellular Processes ◽  
Laboratory Courses ◽  
Biology Laboratory

The Dictyostelium discoideum model system is a powerful tool for undergraduate cell biology teaching laboratories. The cells are biologically safe, grow at room temperature and it is easy to experimentally induce, observe, and perturb a breadth of cellular processes making the system amenable to many teaching lab situations and goals. Here we outline the advantages of Dictyostelium, discuss laboratory courses we teach in three very different educational settings, and provide tips for both the novice and experienced Dictyostelium researcher. With this article and the extensive sets of protocols and tools referenced here, implementing these labs, or parts of them, will be relatively straightforward for any instructor.

scholarly journals Glycan-decorated protocells: novel features for rebuilding cellular processes

2019 ◽  
Vol 9 (2) ◽  
pp. 20180084 ◽  
Author(s):  
Ramin Omidvar ◽  
Winfried Römer
Keyword(s):  
Synthetic Biology ◽  
Membrane Fusion ◽  
Molecular Mechanisms ◽  
Lipid Vesicles ◽  
Cross Linking ◽  
Membrane Systems ◽  
Biophysical Characterization ◽  
Characterization Methods ◽  
Cellular Processes ◽  
Shed Light

In synthetic biology approaches, lipid vesicles are widely used as protocell models. While many compounds have been encapsulated in vesicles (e.g. DNA, cytoskeleton and enzymes), the incorporation of glycocalyx components in the lipid bilayer has attracted much less attention so far. In recent years, glycoconjugates have been integrated in the membrane of giant unilamellar vesicles (GUVs). These minimal membrane systems have largely contributed to shed light on the molecular mechanisms of cellular processes. In this review, we first introduce several preparation and biophysical characterization methods of GUVs. Then, we highlight specific applications of protocells investigating glycolipid-mediated endocytosis of toxins, viruses and bacteria. In addition, we delineate how prototissues have been assembled from glycan-decorated protocells by using lectin-mediated cross-linking of opposed glycoreceptors (e.g. glycolipids and glycopeptides). In future applications, glycan-decorated protocells might be useful for investigating cell–cell interactions (e.g. adhesion and communication). We also speculate about the implication of lectin–glycoreceptor interactions in membrane fusion processes.

VII.—Studies on Reproduction in the Albino Mouse. I. The Period of Gestation and the Time of Parturition

1939 ◽  
Vol 58 ◽  
pp. 80-97 ◽  
Author(s):  
Hugo Merton
Keyword(s):  
Sexual Cycle ◽  
Cellular Processes ◽  
Biological Phenomena ◽  
The Subject ◽  
The Moment ◽  
Period Of Gestation

The cellular processes of ovulation, maturation and fertilisation of the ovum in the albino mouse have been the subject of repeated and exact studies, and are now sufficiently well known. The biological phenomena of propagation in the mouse, i.e. the sexual cycle, œstrus, and copulation, have likewise been described in detail, but our knowledge concerning the period of gestation and the moment of parturition is still very inadequate.

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