scholarly journals Changes in Cell Membrane and Cellular Lipids in Apoptotic Cells Induced by Dolichyl Phosphate Differ from Findings in Cells Induced by Etoposide.

2002 ◽  
Vol 51 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Akiko HORIUCHI ◽  
Etsuko YASUGI ◽  
Chizu IWASAKI ◽  
Keiji FUJIMOTO ◽  
Mieko OSHIMA
Keyword(s):  
Cell Membrane ◽  
Apoptotic Cells ◽  
Dolichyl Phosphate ◽  
Cellular Lipids ◽  
In Cells

scholarly journals Actin Polymerization in Macrophages in Response to Oxidized LDL and Apoptotic Cells: Role of 12/15-Lipoxygenase and Phosphoinositide 3-Kinase

2003 ◽  
Vol 14 (10) ◽  
pp. 4196-4206 ◽  
Author(s):  
Yury I. Miller ◽  
Dorothy S. Worrall ◽  
Colin D. Funk ◽  
James R. Feramisco ◽  
Joseph L. Witztum
Keyword(s):  
Cell Membrane ◽  
Actin Polymerization ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Specific Inhibitor ◽  
Density Lipoprotein ◽  
Oxidation Products ◽  
Apoptotic Cells ◽  
Lipid Oxidation Products ◽  
Phosphoinositide 3 Kinase

Formation of filamentous F-actin drives many cellular processes, including phagocytosis and cell spreading. We have recently reported that mouse macrophage 12/15-lipoxygenase (12/15-LO) activity promotes F-actin formation in filopodia during phagocytosis of apoptotic cells. Oxidized low-density lipoprotein (OxLDL) also stimulates robust F-actin formation and spreading of macrophages. However, unlike apoptotic cells, OxLDL did not cause specific translocation of 12/15-LO to the cell membrane, neither in macrophages nor in GFP-15LO–transfected COS-7 cells. Moreover, inhibition of 12/15-LO activity in macrophages by a specific inhibitor or by 12/15-LO gene disruption did not affect OxLDL-induced actin polymerization. Among LDL modifications modeling OxLDL, LDL modified by incubation with 15LO-overexpressing fibroblasts was as active in eliciting F-actin response as was OxLDL. This LDL modification is well known to produce minimally modified LDL (mmLDL), which is bioactive and carries lipid oxidation products similar to those produced by 12/15-LO catalysis. MmLDL activated phosphoinositide 3-kinase (PI3K), and PI3K inhibitors abolished mmLDL-induced macrophage spreading. We hypothesize that OxLDL and mmLDL may contribute oxidized lipids to the macrophage cell membrane and thereby mimic intracellular 12/15-LO activity, which leads to uncontrolled actin polymerization and dramatic cytoskeletal changes in macrophages.

scholarly journals 3D nanoplasmonic biosensor for detection of filopodia in cells

Lab on a Chip ◽  
2020 ◽  
Vol 20 (12) ◽  
pp. 2188-2196 ◽  
Author(s):  
Shuyan Zhu ◽  
Mohammed A. Eldeeb ◽  
Stella W. Pang
Keyword(s):  
Cell Membrane ◽  
In Cells

Filopodia detection using nanoplasmonic biosensors, where microposts were used to separate the cell membrane from filopodia and 3D nanopillars were used to monitor nanometer-sized filopodia.

Some CLL Cells Bind Myosin-Exposed Apoptotic Cells. Exposure of Cytoplasmic Myosin Results From Transfer of Caspase-3 Dependent Cleavage Products to the Outer Cell Membrane

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3900-3900
Author(s):  
Xiaoxuan Cui ◽  
Lu Zhang ◽  
Amanda R Magli ◽  
Rosa Catera ◽  
Jonathan E Kolitz ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Membrane Protein ◽  
Caspase 3 ◽  
Membrane Surface ◽  
Live Cells ◽  
Parp Cleavage ◽  
Apoptotic Cells ◽  
Prolonged Incubation ◽  
Apoptotic Pathways ◽  
Extrinsic Apoptotic Pathways

Abstract Abstract 3900 Many monoclonal antibodies (mAbs) produced by B-cell chronic lymphocytic leukemia (CLL) cells bind a subset of apoptotic cells that expose intracellular myosin on the cell surface. CLL patients with mAbs that bind these myosin-exposed apoptotic cells (MEACs) have shorter overall survival. Thus, understanding the mechanism of formation of MEACs and how CLL cells interact with MEACs may help elucidate the pathogenesis of CLL. To test if formation of MEACs is part of general apoptotic mechanisms, apoptosis was induced in Jurkat T cells by either the intrinsic or extrinsic pathways. The intrinsic pathway was either achieved spontaneously by culturing at high cell density or induced by camptothecin (CPT) treatment. The extrinsic pathway was induced by Fas ligand (FasL) or anti-Fas mAb treatment. Apoptosis and myosin exposition were analyzed by flow cytometry. All four methods of apoptosis induction produced MEACs after prolonged incubation as detailed below. CPT, FasL or anti-Fas mAb incubation for 4 hrs induced significant apoptosis (43-58%) with a detectable fraction of MEACs (9-12%). After incubation for 16 hrs or longer, the majority of apoptotic cells were MEACs (61-89%). Similarly, spontaneous apoptosis produced more MEACs after longer incubation (20% on day 1 versus 59–69% on days 2–4). Both early apoptotic cells, which flip phosphatidylserine (PS) from the inner to outer membrane surface yet retain membrane integrity (AnnexinV+, 7-actinomycin D (7AAD)-), and late apoptotic cells, which become membrane permeable (AnnexinV+, 7AAD+), demonstrate a subpopulation of MEACs that increases with longer incubation times. In contrast, MEACs are not detectable in non-apoptotic cells (AnnexinV-, 7AAD-). Thus, both intrinsic and extrinsic apoptotic pathways lead to MEAC formation, suggesting that a common downstream mediator may be involved. Caspase-3 activation mediates apoptotic PS exposure and membrane permeability. Therefore, we tested a caspase-3 inhibitor, Z-DEVD-FMK, and found that it significantly reduced both apoptosis and MEAC formation. For example, Z-DEVD-FMK reduced FasL induced apoptosis and MEAC formation from 74 to 14% and from 57 to 10%, respectively. In contrast, caspase-1 inhibitor, Z-YVAD-FMK, had no effect. To test if intracellular myosin is transferred from the cytoplasm to the cell membrane surface during apoptosis, cytoplasmic and membrane protein extracts were prepared, isolated by ultracentrifugation, and blotted with anti-myosin antibody. Two protein bands of the size expected for caspase-3 cleaved myosin (149 and 94 kDa) appeared in membrane extracts of apoptotic cells, but not of live cells. A protein band of the size expected for full-length myosin (250 kDa) predominated in cytoplasmic extracts of live cells. Furthermore, Z-DEVD-FMK inhibited the formation of the 149 and 94 kDa myosin bands in membrane extracts as well as the formation of caspase-3 dependant PARP cleavage products; the same treatment did not alter CD3 membrane protein or GAPDH cytoplasmic protein levels. Taken together, these results suggest that both intrinsic and extrinsic apoptotic pathways produce MEACs at a later stage in apoptosis that involves the common downstream caspase-3 activation. In turn, myosin fragmentation occurs with subsequent exposure to the cell membrane, where the myosin fragments can serve as a potential neoantigen that may be recognized by some CLL mAbs. Because the mAbs we have used in these analyses were originally integral components of CLL surface membranes, we hypothesized that CLL cells could bind MEACs. Indeed, CLL cells binding to MEACs were visualized by confocal microscopy. To determine the functional consequences of such binding, analyses of the effects of MEAC binding on CLL cell survival in vitro are underway. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Inhibition of Apoptosis by Gamma Interferon in Cells and Mice Infected with Chlamydia muridarum (the Mouse Pneumonitis Strain of Chlamydia trachomatis)

2002 ◽  
Vol 70 (5) ◽  
pp. 2559-2565 ◽  
Author(s):  
Jean-Luc Perfettini ◽  
Toni Darville ◽  
Alice Dautry-Varsat ◽  
Roger G. Rank ◽  
David M. Ojcius
Keyword(s):  
Chlamydia Trachomatis ◽  
Inhibitory Effect ◽  
Gamma Interferon ◽  
Apoptotic Cells ◽  
Chlamydia Muridarum ◽  
Infected Cells ◽  
Heterogenous Population ◽  
Ifn Γ ◽  
In Cells

ABSTRACT The effect of gamma interferon (IFN-γ) on apoptosis due to infection by Chlamydia muridarum (the mouse pneumonitis strain of Chlamydia trachomatis) was studied in epithelial cells in culture and in the genital tracts of mice. IFN-γ concentrations that induce the formation of aberrant, persistent chlamydiae inhibit apoptosis due to C. muridarum infection. In cells treated with an IFN-γ concentration that leads to the development of a heterogenous population of normal and aberrant Chlamydia vacuoles, apoptosis was inhibited preferentially in cells that contained the aberrant vacuoles. The inhibitory effect of IFN-γ appears to be due in part to expression of host cell indoleamine 2,3-dioxygenase activity, since inhibition of apoptosis could be partially reversed through coincubation with exogenous tryptophan. Apoptotic cells were observed in the genital tracts of wild-type mice infected with C. muridarum, and a significantly larger number of apoptotic cells was detected in infected IFN-γ-deficient mice. These results suggest that IFN-γ may contribute to pathogenesis of persistent Chlamydia infections in vivo by preventing apoptosis of infected cells.

scholarly journals THE PHOTOSYNTHETIC APPARATUS OF RHODOSPIRILLUM MOLISCHIANUM

1965 ◽  
Vol 26 (2) ◽  
pp. 395-412 ◽  
Author(s):  
Sarah P. Gibbs ◽  
W. R. Sistrom ◽  
Patricia B. Worden
Keyword(s):  
Cell Membrane ◽  
Photosynthetic Apparatus ◽  
Variable Number ◽  
Electron Microscopic ◽  
Microscopic Appearance ◽  
Whole Cells ◽  
Cell Extracts ◽  
Internal Membrane ◽  
Rhodospirillum Molischianum ◽  
In Cells

By varying the light intensity and temperature during growth it is possible to obtain cultures of Rhodospirillum molischianum in which the specific bacteriochlorophyll contents differ by as much as fivefold. We used such cultures to compare the changes in the electron microscopic appearance of the cells with the changes in the amount and bacteriochlorophyll content of chromatophore material isolated from cell extracts. The cells contained a variable number of internal membranes which are invaginations of the cell membrane. The shape, size, number, and arrangement of the infoldings varied as the specific bacteriochlorophyll content of the cells changed. In cells with little bacteriochlorophyll, the invaginations were mostly tubular. In cells with larger amounts of bacteriochlorophyll, the invaginations were disc-shaped and the discs were appressed together in stacks of 2 to 10 discs each. Variations in the number of discs per stack could be accounted for by a simple statistical model. The average area per disc increased with increasing bacteriochlorophyll content. Quantitative estimations of the relative volumes occupied by membranes in cells with four different bacteriochlorophyll contents showed that the amount of internal membrane alone had no direct relationship with the bacteriochlorophyll content of the cells; however, the total amount of membrane (cell membrane plus internal membrane) was directly proportional to the bacteriochlorophyll content. The specific bacteriochlorophyll content of isolated chromatophore material was proportional to the bacteriochlorophyll content of whole cells; the total amount of chromatophore material was independent of the bacteriochlorophyll content of whole cells. Several possible explanations of this paradoxical discrepancy between the electron microscope observations and the analytical results are discussed.

Oxytocin-induced changes in single cell K+ currents and smooth muscle contraction of guinea-pig gastric antrum

1997 ◽  
Vol 136 (5) ◽  
pp. 531-538 ◽  
Author(s):  
Dessislava B Duridanova ◽  
Milena D Nedelcheva ◽  
Hristo S Gagov
Keyword(s):  
Smooth Muscle ◽  
Cell Membrane ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Gastric Antrum ◽  
Dependent Manner ◽  
Response Curves ◽  
Dose Dependent ◽  
In Cells

Abstract To study the effects of oxytocin on both spontaneous phasic contractions and K+ outward currents (IK) of the so-called 'non-target' smooth muscle cells, physiological concentrations of oxytocin ranging between 10−12 mol/l and 10−8 mol/l were applied to smooth muscle preparations and single voltage-clamped cells isolated from the circular layer of the guinea-pig gastric antrum. Oxytocin (10−12mol/l to 10−8 mol/l) suppressed, in a dose-dependent manner, the tetrodotoxin- and atropine-resistant spontaneous phasic contractions and shifted rightward the dose–response curves of 10−7 mol/l charybdotoxin and 10−3mol/l BaCl2. In cells with preloaded intracellular Ca2+ stores, oxytocin (10−12 mol/l to 10−9 mol/l) caused a dose-dependent activation of the charybdotoxin-blockable non-inactivating component of IK (IK(s1)) of single voltage-clamped cells, which was accompanied by hyperpolarization of the cell membranes. 8Lys-vasopressin and 8arg-vasopressin failed to mimic the effects of oxytocin on both contraction and K+ currents. Further, the oxytocin-induced activation of IK(s1) was effectively antagonized by 5× 10−8 mol/l U-73122 or 5× 10−6 mol/l 2-nitro-4-carboxyphenyl N,N-diphenylcarbamate (inhibitors of the cell membrane phospholipase C), as well as by intracellularly applied heparin (selective inhibitor of inositol-1,4,5-trisphosphate (IP3)-induced Ca2+ release channels). In cells incubated in the absence of Ca2+ entry throughout the study, oxytocin (10−9 mol/l) caused a slight and transient increase of IK(s1) amplitudes. Neither ryanodine (10−6 mol/l nor cyclopiazonic acid (10−6 mol/l) were able to restore the IK-activating effect of oxytocin in these cells. The data obtained suggest (i) that selective oxytocin receptors are present on the membranes of guinea-pig antral smooth muscle cells, (ii) that the oxytocin-related relaxation may result from the activation of Ca2+-sensitive K+ conductivity via activation of IP3-induced release of Ca from the submembrane located cisternae of the sarcoplasmic reticulum Ca2+ stores and (iii) in turn, this evokes a non-inactivating component of IK, hyperpolarizing the cell membrane. European Journal of Endocrinology 136 531–538

Distribution of ytterbium (Yb) in cells of Streptomyces sp. YB-1 which can accumulate Yb, and reusability of cells and cell membrane as bioadsorbent for Yb

2004 ◽  
Vol 98 (3) ◽  
pp. 214-216 ◽  
Author(s):  
Ambar Pertiwiningrum ◽  
Yoshinaka Ino ◽  
Tohru Suzuki ◽  
Tomonori Iwama ◽  
Keiichi Kawai
Keyword(s):  
Cell Membrane ◽  
Streptomyces Sp ◽  
In Cells
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