scholarly journals Endoplasmic reticulum remains continuous and undergoes sheet-to-tubule transformation during cell division in mammalian cells

2007 ◽  
Vol 179 (5) ◽  
pp. 895-909 ◽  
Author(s):  
Maija Puhka ◽  
Helena Vihinen ◽  
Merja Joensuu ◽  
Eija Jokitalo
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Division ◽  
3D Modeling ◽  
Mammalian Cells ◽  
Structural Changes ◽  
Electron Tomography ◽  
Morphological Changes ◽  
Homogenous Distribution ◽  
Membrane Bound ◽  
Cycle Dependent

The endoplasmic reticulum (ER) is a multifaceted cellular organelle both structurally and functionally, and its cell cycle–dependent morphological changes are poorly understood. Our quantitative confocal and EM analyses show that the ER undergoes dramatic reorganization during cell division in cultured mammalian cells as mitotic ER profiles become shorter and more branched. 3D modeling by electron tomography reveals that the abundant interphase structures, sheets, are lost and subsequently transform into a branched tubular network that remains continuous. This is confirmed by observing the most prominent ER subdomain, the nuclear envelope (NE). A NE marker protein spreads to the mitotic ER tubules, although it does not show a homogenous distribution within the network. We mimicked the mitotic ER reorganization using puromycin to strip the membrane-bound ribosomes from the interphase ER corresponding to the observed loss of ribosomes normally occurring during mitosis. We propose that the structural changes in mitotic ER are linked to ribosomal action on the ER membranes.

scholarly journals Zika virus replication in glioblastoma cells: electron microscopic tomography shows 3D arrangement of endoplasmic reticulum, replication organelles, and viral ribonucleoproteins

2021 ◽  
Author(s):  
Johannes Wieland ◽  
Stefan Frey ◽  
Ulrich Rupp ◽  
Sandra Essbauer ◽  
Rüdiger Groß ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Line ◽  
Zika Virus ◽  
Structural Changes ◽  
Electron Tomography ◽  
Glioblastoma Cells ◽  
Electron Microscopic ◽  
N Protein ◽  
Ribonucleoprotein Complexes ◽  
Infected Cells

AbstractStructural changes of two patient-derived glioblastoma cell lines after Zika virus infection were investigated using scanning transmission electron tomography on high-pressure-frozen, freeze-substituted samples. In Zika-virus-infected cells, Golgi structures were barely visible under an electron microscope, and viral factories appeared. The cytosol outside of the viral factories resembled the cytosol of uninfected cells. The viral factories contained largely deranged endoplasmic reticulum (ER), filled with many so-called replication organelles consisting of a luminal vesicle surrounded by the ER membrane. Viral capsids were observed in the vicinity of the replication organelles (cell line #12537 GB) or in ER cisternae at large distance from the replication organelles (cell line #15747 GB). Near the replication organelles, we observed many about 100-nm-long filaments that may represent viral ribonucleoprotein complexes (RNPs), which consist of the RNA genome and N protein oligomers. In addition, we compared Zika-virus-infected cells with cells infected with a phlebovirus (sandfly fever Turkey virus). Zika virions are formed in the ER, whereas phlebovirus virions are assembled in the Golgi apparatus. Our findings will help to understand the replication cycle in the virus factories and the building of the replication organelles in glioblastoma cells.

Role of an endoplasmic reticulum Ca2+-independent phospholipase A2 in oxidant-induced renal cell death

2002 ◽  
Vol 283 (3) ◽  
pp. F492-F498 ◽  
Author(s):  
Brian S. Cummings ◽  
Jane McHowat ◽  
Rick G. Schnellmann
Keyword(s):  
Lipid Peroxidation ◽  
Endoplasmic Reticulum ◽  
Subcellular Localization ◽  
Mammalian Cells ◽  
Cumene Hydroperoxide ◽  
Physiological Role ◽  
Antimycin A ◽  
Bacterial Cells ◽  
Tert Butylhydroperoxide ◽  
Membrane Bound

Phospholipase A2(PLA2) hydrolyzes the sn-2 ester bond in phospholipids, releasing a fatty acid and a lysophospholipid. Recently, a novel 85-kDa membrane-bound-Ca2+-independent PLA2 (iPLA2) was identified in insect and bacterial cells transfected with candidate PLA2 sequences. However, few data exist demonstrating a membrane-bound-iPLA2 in mammalian cells, its subcellular localization, or its physiological role. Herein, we demonstrate the expression of an 85-kDa endoplasmic reticulum (ER)-Ca2+-iPLA2 (ER-iPLA2) in rabbit renal proximal tubule cells (RPTC) that is plasmalogen selective and is inhibited by the specific Ca2+-iPLA2inhibitor bromoenol lactone (BEL). RPTC exposed to tert-butylhydroperoxide for 24 h exhibited 20% oncosis compared with 2% in controls. Inhibition of ER-iPLA2 with BEL before tert-butylhydroperoxide exposure resulted in 50% oncosis. To determine whether this effect was common to oxidants, we tested the ability of BEL to potentiate oncosis induced by cumene hydroperoxide, menadione, duraquinone, cisplatin, and the nonoxidant antimycin A. All oxidants tested produced oncosis after 24 h, and prior inhibition of ER-iPLA2 potentiated oncosis at least twofold. In contrast, inhibition of ER-iPLA2 did not alter antimycin A-induced oncosis. Lipid peroxidation increased from 1.4- to 5.2-fold in RPTC treated with BEL before oxidant exposure, whereas no change was seen in antimycin A-treated RPTC. These results are the first to demonstrate the expression and subcellular localization of an ER-iPLA2. These results also suggest that ER-iPLA2 functions to protect against oxidant-induced lipid peroxidation and oncosis.

2P192 Cell cycle-dependent dynamics of the endoplasmic reticulum (ER) in mammalian cells (I): Mechanism of disruption of the ER network

2004 ◽  
Vol 44 (supplement) ◽  
pp. S157
Author(s):  
A.R. Tanaka ◽  
P. Kano ◽  
H. Kondo ◽  
S. Yamauchi ◽  
N. Hosokawa ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Endoplasmic Reticulum ◽  
Mammalian Cells ◽  
Cycle Dependent

scholarly journals Postlipolytic insulin-dependent remodeling of micro lipid droplets in adipocytes

2012 ◽  
Vol 23 (10) ◽  
pp. 1826-1837 ◽  
Author(s):  
Nicholas Ariotti ◽  
Samantha Murphy ◽  
Nicholas A. Hamilton ◽  
Lizhen Wu ◽  
Kathryn Green ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Endoplasmic Reticulum ◽  
Lipid Droplets ◽  
Electron Tomography ◽  
Morphological Changes ◽  
Quantitative Imaging ◽  
The Reformation ◽  
Fundamental Process ◽  
Insulin Dependent ◽  
Fat Pads

Despite the lipolysis–lipogenesis cycle being a fundamental process in adipocyte biology, very little is known about the morphological changes that occur during this process. The remodeling of lipid droplets to form micro lipid droplets (mLDs) is a striking feature of lipolysis in adipocytes, but once lipolysis ceases, the cell must regain its basal morphology. We characterized mLD formation in cultured adipocytes, and in primary adipocytes isolated from mouse epididymal fat pads, in response to acute activation of lipolysis. Using real-time quantitative imaging and electron tomography, we show that formation of mLDs in cultured adipocytes occurs throughout the cell to increase total LD surface area by ∼30% but does not involve detectable fission from large LDs. Peripheral mLDs are monolayered structures with a neutral lipid core and are sites of active lipolysis. Electron tomography reveals preferential association of mLDs with the endoplasmic reticulum. Treatment with insulin and fatty acids results in the reformation of macroLDs and return to the basal state. Insulin-dependent reformation of large LDs involves two distinct processes: microtubule-dependent homotypic fusion of mLDs and expansion of individual mLDs. We identify a physiologically important role for LD fusion that is involved in a reversible lipolytic cycle in adipocytes.

scholarly journals A novel automated image analysis pipeline for quantifying morphological changes to the endoplasmic reticulum in cultured human cells

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
M. Elena Garcia-Pardo ◽  
Jeremy C. Simpson ◽  
Niamh C. O’Sullivan
Keyword(s):  
Endoplasmic Reticulum ◽  
Image Analysis ◽  
Mammalian Cells ◽  
Large Scale ◽  
Morphological Changes ◽  
Methodological Approach ◽  
Automated Image Analysis ◽  
Adherent Cell ◽  
Analysis Pipeline ◽  
Cultured Human Cells

Abstract Background In mammalian cells the endoplasmic reticulum (ER) comprises a highly complex reticular morphology that is spread throughout the cytoplasm. This organelle is of particular interest to biologists, as its dysfunction is associated with numerous diseases, which often manifest themselves as changes to the structure and organisation of the reticular network. Due to its complex morphology, image analysis methods to quantitatively describe this organelle, and importantly any changes to it, are lacking. Results In this work we detail a methodological approach that utilises automated high-content screening microscopy to capture images of cells fluorescently-labelled for various ER markers, followed by their quantitative analysis. We propose that two key metrics, namely the area of dense ER and the area of polygonal regions in between the reticular elements, together provide a basis for measuring the quantities of rough and smooth ER, respectively. We demonstrate that a number of different pharmacological perturbations to the ER can be quantitatively measured and compared in our automated image analysis pipeline. Furthermore, we show that this method can be implemented in both commercial and open-access image analysis software with comparable results. Conclusions We propose that this method has the potential to be applied in the context of large-scale genetic and chemical perturbations to assess the organisation of the ER in adherent cell cultures.

scholarly journals Das endoplasmatische Retikulum in der Mitose — ein wandelbares Netz

BIOspektrum ◽  
2020 ◽  
Vol 26 (7) ◽  
pp. 739-742
Author(s):  
Anne Schlaitz
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Division ◽  
Nuclear Envelope ◽  
Molecular Mechanisms ◽  
Detailed Understanding ◽  
Membrane Bound

AbstractIn order to divide successfully, cells need to reorganize their interior including membrane-bound organelles such as the endoplasmic reticulum (ER). The ER serves as sink and source for the nuclear envelope and undergoes distinct transformations in its morphology and dynamics during cell division. To fully appreciate the functions of ER remodeling during cell division it will be essential to first achieve a detailed understanding of the underlying molecular mechanisms.

scholarly journals 2P193 Cell cycle-dependent dynamics of the endoplasmic reticulum (ER) in mammalian cells (II) : Mechanism of membrane fusion of the ER

2004 ◽  
Vol 44 (supplement) ◽  
pp. S158
Author(s):  
F. Kano ◽  
H. Kondo ◽  
S. Yamauchi ◽  
A.R. Tanaka ◽  
N. Hosokawa ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Endoplasmic Reticulum ◽  
Membrane Fusion ◽  
Mammalian Cells ◽  
Cycle Dependent

scholarly journals Cisternal Organization of the Endoplasmic Reticulum during Mitosis

2009 ◽  
Vol 20 (15) ◽  
pp. 3471-3480 ◽  
Author(s):  
Lei Lu ◽  
Mark S. Ladinsky ◽  
Tom Kirchhausen
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Mammalian Cells ◽  
Three Dimensional ◽  
Freeze Substitution ◽  
High Resolution Electron Microscopy ◽  
Animal Cells ◽  
Resolution Electron ◽  
Major Transformation ◽  
Membrane Bound

The endoplasmic reticulum (ER) of animal cells is a single, dynamic, and continuous membrane network of interconnected cisternae and tubules spread out throughout the cytosol in direct contact with the nuclear envelope. During mitosis, the nuclear envelope undergoes a major rearrangement, as it rapidly partitions its membrane-bound contents into the ER. It is therefore of great interest to determine whether any major transformation in the architecture of the ER also occurs during cell division. We present structural evidence, from rapid, live-cell, three-dimensional imaging with confirmation from high-resolution electron microscopy tomography of samples preserved by high-pressure freezing and freeze substitution, unambiguously showing that from prometaphase to telophase of mammalian cells, most of the ER is organized as extended cisternae, with a very small fraction remaining organized as tubules. In contrast, during interphase, the ER displays the familiar reticular network of convolved cisternae linked to tubules.

scholarly journals Organization of the endoplasmic reticulum in cells of effective and ineffective pea nodules (Pisum sativum L.)

2019 ◽  
Vol 17 (4) ◽  
pp. 5-14
Author(s):  
Anna V. Tsyganova ◽  
Viktor E. Tsyganov
Keyword(s):  
Endoplasmic Reticulum ◽  
Pisum Sativum ◽  
Structural Changes ◽  
Nodule Development ◽  
Wild Type ◽  
Meristematic Cells ◽  
Pisum Sativum L ◽  
Transmission Electron ◽  
Infected Cells ◽  
Membrane Bound

Background. The endoplasmic reticulum (ER) is the largest membrane-bound organelle, which plays an important role in the functioning of a plant cell and participates in its differentiation. Materials and methods. Using the methods of transmission electron microscopy, the morphological features and dynamics of structural changes in the ER in symbiotic nodules of pea (Pisum sativum L.) wild-type and mutants blocked at different stages of nodule development were studied. Results. ER developed from a network of individual tubules in meristematic cells, to a developed network of cisterns around the nucleus and plasmalemma, and a network of granular and smooth tubules accompanying infection structures in colonized and infected cells and symbiosomes in infected cells. Conclusions. A correlation was found between the level of development of the ER network and the degree of bacteroid differentiation.

scholarly journals A cryo-ET survey of intracellular compartments within mammalian axons

2021 ◽  
Author(s):  
Helen E Foster ◽  
Camilla Ventura Santos ◽  
Andrew P Carter
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Body ◽  
Small Groups ◽  
Motor Proteins ◽  
Electron Tomography ◽  
Sensory Axons ◽  
Cryo Electron Tomography ◽  
Intracellular Compartments ◽  
Membrane Bound ◽  
Beaded Appearance

The neuronal axon contains many intracellular compartments which travel between the cell body and axon tip. The nature of these cargos and the complex axonal environment through which they traverse is unclear. Here, we describe the internal components of mammalian sensory axons using cryo-electron tomography. We show that axonal endoplasmic reticulum has thin, beaded appearance and is tethered to microtubules at multiple sites. The tethers are elongated, ~7 nm long proteins which cluster in small groups. We survey the different membrane-bound cargos in axons, quantify their abundance and describe novel internal features including granules and broken membranes. We observe connecting density between membranes and microtubules which may correspond to motor proteins. In addition to membrane-bound organelles, we detect numerous proteinaceous compartments, including vaults and previously undescribed virus-like capsid particles. The abundance of these compartments suggests they undergo trafficking in axons. Our observations outline the physical characteristics of axonal cargo and provide a platform for identification of their constituents.

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