scholarly journals Three-dimensional cell geometry controls excitable membrane signaling in Dictyotelium cells

2018 ◽  
Author(s):  
Marcel Hörning ◽  
Tatsuo Shibata
Keyword(s):  
Plasma Membrane ◽  
Mammalian Cells ◽  
Three Dimensional ◽  
Reaction Diffusion ◽  
Membrane Topology ◽  
Membrane Area ◽  
Wave Dynamics ◽  
Entire Cell ◽  
Membrane Signaling ◽  
Dimensional Cell

AbstractPhosphatidylinositol (3,4,5)-trisphosphate (PtdInsP3) is known to propagate as waves on the plasma membrane and is related to the membrane protrusive activities in Dictyostelium and mammalian cells. While there have been a few attempts to study the three-dimensional dynamics of these processes, most studies have focused on the dynamics extracted from single focal planes. However, the relation between the dynamics and three-dimensional cell shape remains elusive, due to the lack of signaling information about the unobserved part of the membrane. Here we show that PtdInsP3 wave dynamics are directly regulated by the three-dimensional geometry - size and shape - of the plasma membrane. By introducing an analysis method that extracts the three-dimensional spatiotemporal activities on the entire cell membrane, we show that PtdInsP3 waves self-regulate their dynamics within the confined membrane area. This leads to changes in speed, orientation and pattern evolution, following the underlying excitability of the signal transduction system. Our findings emphasize the role of the plasma membrane topology in reaction-diffusion driven biological systems and indicate its importance in other mammalian systems.

Preparation of Porous Organically-Modified Silicate Hybrids for Cell Culture Matrix

2007 ◽  
Vol 330-332 ◽  
pp. 1177-1180 ◽  
Author(s):  
Kanji Tsuru ◽  
Satoshi Hayakawa ◽  
Yuki Shirosaki ◽  
T. Okayama ◽  
K. Kataoka ◽  
...  
Keyword(s):  
Cell Culture ◽  
Mammalian Cells ◽  
Pore Diameter ◽  
Sol Gel ◽  
Three Dimensional ◽  
Culture Methods ◽  
Organically Modified ◽  
Dimensional Cell

Porous & rubbery organic-inorganic hybrids were synthesized from tetraethoxysilane (TEOS) and polydimethylsiloxane (PDMS) through a sol-gel route using sieved sucrose granules as a porogen. The porous hybrids with a high content of PDMS behaved like polymer sponge. The porosity was over 90% irrespective of the hybrid composition and the pore diameter ranged from 100 to 500 μm. In the three-dimensional cell culture, mammalian cells were well cultured in the porous hybrids. The present results indicate that the hybrids may be a promising scaffold for developing such functional culture methods.

scholarly journals Plasmodium falciparum exports the Golgi marker sphingomyelin synthase into a tubovesicular network in the cytoplasm of mature erythrocytes

1994 ◽  
Vol 124 (4) ◽  
pp. 449-462 ◽  
Author(s):  
HG Elmendorf ◽  
K Haldar
Keyword(s):  
Plasmodium Falciparum ◽  
Plasma Membrane ◽  
Mammalian Cells ◽  
Three Dimensional ◽  
Eukaryotic Cell ◽  
Biosynthetic Activity ◽  
Trophozoite Stage ◽  
Mature Erythrocyte ◽  
Sphingomyelin Synthase ◽  
Membrane Development

This work describes two unusual features of membrane development in a eukaryotic cell. (a) The induction of an extensive network of tubovesicular membranes by the malaria parasite Plasmodium falciparum in the cytoplasm of the mature erythrocyte, and its visualization with two ceramide analogues C5-DMB-ceramide and C6-NBD-ceramide. "Sectioning" of the infected erythrocytes using laser confocal microscopy has allowed the reconstruction of detailed three-dimensional images of this novel membrane network. (b) The stage-specific export of sphingomyelin synthase, a biosynthetic activity concentrated in the Golgi of mammalian cells, to this tubovesicular network. Evidence is presented that in the extracellular merozoite stage the parasite retains sphingomyelin synthase within its plasma membrane. However, intracellular ring- and trophozoite-stage parasites export a substantial fraction (approximately 26%) of sphingomyelin synthase activity to membranes beyond their plasma membrane. Importantly we do not observe synthesis of new enzyme during these intracellular stages. Taken together these results strongly suggest that the export of this classic Golgi enzyme is developmentally regulated in Plasmodium. We discuss the significance of this export and the tubovesicular network with respect to membrane development and function in the erythrocyte cytosol.

scholarly journals Three-dimensional architecture of extended synaptotagmin-mediated endoplasmic reticulum–plasma membrane contact sites

2015 ◽  
Vol 112 (16) ◽  
pp. E2004-E2013 ◽  
Author(s):  
Rubén Fernández-Busnadiego ◽  
Yasunori Saheki ◽  
Pietro De Camilli
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Mammalian Cells ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Lipid Binding ◽  
Dense Layer ◽  
Lipid Transfer ◽  
C2 Domains ◽  
Membrane Contact Sites

The close apposition between the endoplasmic reticulum (ER) and the plasma membrane (PM) plays important roles in Ca2+ homeostasis, signaling, and lipid metabolism. The extended synaptotagmins (E-Syts; tricalbins in yeast) are ER-anchored proteins that mediate the tethering of the ER to the PM and are thought to mediate lipid transfer between the two membranes. E-Syt cytoplasmic domains comprise a synaptotagmin-like mitochondrial-lipid–binding protein (SMP) domain followed by five C2 domains in E-Syt1 and three C2 domains in E-Syt2/3. Here, we used cryo-electron tomography to study the 3D architecture of E-Syt–mediated ER–PM contacts at molecular resolution. In vitrified frozen-hydrated mammalian cells overexpressing individual E-Syts, in which E-Syt–dependent contacts were by far the predominant contacts, ER–PM distance (19–22 nm) correlated with the amino acid length of the cytosolic region of E-Syts (i.e., the number of C2 domains). Elevation of cytosolic Ca2+ shortened the ER–PM distance at E-Syt1–dependent contacts sites. E-Syt–mediated contacts displayed a characteristic electron-dense layer between the ER and the PM. These features were strikingly different from those observed in cells exposed to conditions that induce contacts mediated by the stromal interaction molecule 1 (STIM1) and the Ca2+ channel Orai1 as well as store operated Ca2+ entry. In these cells the gap between the ER and the PM was spanned by filamentous structures perpendicular to the membranes. Our results define specific ultrastructural features of E-Syt–dependent ER–PM contacts and reveal their structural plasticity, which may impact on the cross-talk between the ER and the PM and the functions of E-Syts in lipid transport between the two bilayers.

scholarly journals Can keratin scaffolds be used for creating three-dimensional cell cultures?

Open Medicine ◽  
2020 ◽  
Vol 15 (1) ◽  
pp. 249-253
Author(s):  
Marta Bochynska-Czyz ◽  
Patrycja Redkiewicz ◽  
Hanna Kozlowska ◽  
Joanna Matalinska ◽  
Marek Konop ◽  
...  
Keyword(s):  
Cell Cultures ◽  
Chemical Activation ◽  
Three Dimensional ◽  
Enzymatic Digestion ◽  
Pepsin Digestion ◽  
Cell Culturing ◽  
3D Cell Cultures ◽  
Associated Proteins ◽  
Positive Effect ◽  
Dimensional Cell

AbstractThree-dimensional (3D) cell cultures were created with the use of fur keratin associated proteins (F-KAPs) as scaffolds. The procedure of preparation F-KAP involves combinations of chemical activation and enzymatic digestion. The best result in porosity and heterogeneity of F-KAP surface was received during pepsin digestion. The F-KAP had a stable structure, no changes were observed after heat treatment, shaking and washing. The 0.15-0.5 mm fraction had positive effect for formation of 3D scaffolds and cell culturing. Living rat mesenchymal cells on the F-KAP with no abnormal morphology were observed by SEM during 32 days of cell culturing.

scholarly journals Factors to consider when interrogating 3D culture models with plate readers or automated microscopes

2021 ◽  
Author(s):  
Terry Riss ◽  
O. Joseph Trask
Keyword(s):  
Cell Culture ◽  
Three Dimensional ◽  
3D Culture ◽  
Fluorescent Imaging ◽  
Culture Models ◽  
Assay Methods ◽  
Diffusion Rates ◽  
Cell Culture Models ◽  
Dimensional Cell ◽  
Cells Cultured

AbstractAlong with the increased use of more physiologically relevant three-dimensional cell culture models comes the responsibility of researchers to validate new assay methods that measure events in structures that are physically larger and more complex compared to monolayers of cells. It should not be assumed that assays designed using monolayers of cells will work for cells cultured as larger three-dimensional masses. The size and barriers for penetration of molecules through the layers of cells result in a different microenvironment for the cells in the outer layer compared to the center of three-dimensional structures. Diffusion rates for nutrients and oxygen may limit metabolic activity which is often measured as a marker for cell viability. For assays that lyse cells, the penetration of reagents to achieve uniform cell lysis must be considered. For live cell fluorescent imaging assays, the diffusion of fluorescent probes and penetration of photons of light for probe excitation and fluorescent emission must be considered. This review will provide an overview of factors to consider when implementing assays to interrogate three dimensional cell culture models.

SELF-ASSEMBLED SCAFFOLDS USING REACTION–DIFFUSION SYSTEMS: A HYPOTHESIS FOR BONE REGENERATION

2011 ◽  
Vol 11 (01) ◽  
pp. 231-272 ◽  
Author(s):  
DIEGO A. GARZÓN-ALVARADO ◽  
MARCO A. VELASCO ◽  
CARLOS A. NARVÁEZ-TOVAR
Keyword(s):  
Bone Matrix ◽  
Three Dimensional ◽  
Reaction Diffusion ◽  
Tissue Growth ◽  
New Bone Formation ◽  
Reaction Diffusion Systems ◽  
Bone Scaffolds ◽  
Full Control ◽  
Diffusion Systems ◽  
Biomaterial Scaffold

One area of tissue engineering concerns research into alternatives for new bone formation and replacing its function. Scaffolds have been developed to meet this requirement, allowing cell migration, bone tissue growth, transport of growth factors and nutrients, and the improvement of the mechanical properties of bone. Scaffolds are made from different biomaterials and manufactured using several techniques that, in some cases, do not allow full control over the size and orientation of the pores characterizing the scaffold. A novel hypothesis that a reaction–diffusion (RD) system can be used for designing the geometrical specifications of the bone matrix is thus presented here. The hypothesis was evaluated by making simulations in two- and three-dimensional RD systems in conjunction with the biomaterial scaffold. The results showed the methodology's effectiveness in controlling features such as the percentage of porosity, size, orientation, and interconnectivity of pores in an injectable bone matrix produced by the proposed hypothesis.

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