scholarly journals Cytochalasin B inhibits actin-related gelation of HeLa cell extracts.

1976 ◽  
Vol 71 (1) ◽  
pp. 303-307 ◽  
Author(s):  
R R Weihing
Keyword(s):  
Plasma Membrane ◽  
Hela Cell ◽  
Hela Cells ◽  
Membrane Fraction ◽  
Cytochalasin B ◽  
Supernatant Fraction ◽  
Cell Extracts ◽  
Triton X ◽  
In Vivo Effects

When the 100,000 g supernatant fraction (extract) of HeLa cells lysed in a buffer containing sucrose, ATP, DTE, EGTA, imidazole, and Triton X-100 is incubated at 25 degrees C, it gels, and actin and a HMWP are progressively enriched in the extract and in gel isolated from extract. CB (greater than or equal to 0.25 muM) inhibits gelation and specifically lowers the concentrations of actin and the HMWP in the fraction which sediments at 100,000 g after incubation. These results indicate that actin and HMWP are partly disaggregated by cytochalasin treatment, and thus that their aggregation is related gelation. Inasmuch as previous results showed that actin is present and HMWP is enriched in the plasma membrane fraction of HeLa cells, the results also point to a possible relation between plasma membrane-associated gel and in vivo effects of CB.

scholarly journals Effects of myosin and heavy meromyosin on actin-related gelation of HeLa cell extracts.

1977 ◽  
Vol 75 (1) ◽  
pp. 95-103 ◽  
Author(s):  
R R Weihing
Keyword(s):  
Hela Cell ◽  
Hela Cells ◽  
Supernatant Fraction ◽  
Gel Formation ◽  
Heavy Meromyosin ◽  
Dynamic Changes ◽  
Cell Extracts ◽  
Weight Protein ◽  
Cold Spring ◽  
Triton X

The gelation induced by warming (to 25 degrees C) the 100,000 g supernatant fraction (extract) of HeLa cells lysed in a buffer containing sucrose, ATP, DTE, EGTA, imidazole, and Triton X-100 was studied in the presence of myosin and heavy meromyosin (HMM). Myosin mixed with extract induces shrinkage of the gel, but jelled extract or myosin alone does not shrink. In the concentration range, 0.14-1.04 mg/ml of myosin, the degree of shrinkage is roughly proportional to the concentration of myosin. Supplementa MgCl2 also promotes shrinkage. HMM (0.4-0.8 mg/ml) can inhibit gel formation by extract in tubes or floated on a sucrose cushion. Gel electrophoresis of gels shrunken by added myosin or electrophoresis of the proteins which can be sedimented from extract after incubation in the presence of HMM indicate that both myosin and HMM interfere with the changes in sedimentability of the high molecular weight protein (HMWP) thought to participate (together with actin) in gel formation in HeLa cell extracts (R. R. Weihing, 1976. J. Cell Biol. 71:303-307). These results, together with previous results showing that actin is present and that HMWP is enriched in the plasma membrane fraction of HeLa cells (R. R. Weihing, 1976. Cold Spring Harbor Conf. Cell Proliferation. 3:671-684), point to the possibility of dynamic changes in the interactions of HMWP or myosin with actin in processes of movement occurring at the cell surface.

Association of the hepatic IP3 receptor with the plasma membrane: relevance to mode of action

1993 ◽  
Vol 265 (6) ◽  
pp. C1588-C1596 ◽  
Author(s):  
L. Feng ◽  
N. Kraus-Friedmann
Keyword(s):  
Plasma Membrane ◽  
Membrane Fraction ◽  
Ip3 Receptors ◽  
Ip3 Receptor ◽  
Plasma Membrane Fraction ◽  
T Lymphoma Cells ◽  
T Lymphoma ◽  
Triton X ◽  
Brain Receptor ◽  
The Brain

Studies were carried out to characterize the interaction between inositol 1,4,5-trisphosphate (IP3) receptors and the plasma membrane fraction. Extraction of the membranes with the nonionic detergents Nonidet P-40 and Triton X-100, followed by centrifugation at 100,000 g, resulted in the doubling of the IP3 receptor in the pellets, whereas no detectable binding was found in the supernatants. These data indicate that the detergents did not solubilize the receptor, that it remained associated with membrane particles, and that it is likely to be associated with the cytoskeleton. The cytoskeleton proteins actin, ankyrin, and spectrin were identified in the plasma membrane fraction. However, comparison of the amount of these proteins in different fractions of the detergent, or otherwise treated plasma membrane fractions, showed no direct correlation between the presence of any of these proteins in the plasma membrane fraction and their ability to bind [3H]IP3. This is in contrast to the brain and T-lymphoma cells in which the IP3 receptor is attached to ankyrin (L. Y. W. Bourguigon, H. Jin, N. Iida, N. R. Brandt, and S. H. Zhang. J. Biol. Chem. 268: 6477-6486, 1993; and S. K. Joseph and S. Samanta. J. Biol. Chem 268: 6477-6486, 1993). Thus the hepatic IP3 receptor, which is different from the brain receptor, might attach to the cytoskeleton by anchoring to a different protein. Because cytochalasin D treatment of livers diminishes the ability of IP3 to raise cytosolic free Ca2+ levels, the attachment of the IP3 receptor to the cytoskeleton seems to involve an association with microfilaments.

Ability to organize microtubules in taxol-treated mitotic PtK2 cells goes with the SPN antigen and not with the centrosome

1992 ◽  
Vol 102 (1) ◽  
pp. 91-102 ◽  
Author(s):  
M. Kallajoki ◽  
K. Weber ◽  
M. Osborn
Keyword(s):  
Plasma Membrane ◽  
Hela Cells ◽  
Nuclear Matrix ◽  
Essential Role ◽  
Soluble Form ◽  
Microtubule Nucleation ◽  
Brain Microtubules ◽  
Mitotic Cells

The SPN antigen plays an essential role in mitosis, since microinjection of antibodies causes mitotic arrest. Here we show, by examination of the relative locations of SPN antigen, the centrosomal 5051 antigen and tubulin in normal mitotic, and in taxol-treated mitotic cells, that the SPN antigen is involved in organizing the microtubules of the spindle. The 210 kDa protein defined as SPN antigen relocates from the nuclear matrix to the centrosome at prophase, remains associated with the poles at metaphase and anaphase, and dissociates from the centrosomes in telophase. In taxol-treated mitotic cells, SPN staining shows a striking redistribution while 5051 antigen remains associated with centrosomes. SPN antigen is seen at the plasma membrane end of the rearranged microtubules. SPN antigen is always at the center of the multiple microtubule asters (5 to 20 per cell) induced by taxol, whereas 5051 again remains associated with the centrosomal complex (1 to 2 foci per cell). Microtubule nucleation is associated with the SPN antigen rather than with the 5051 antigen. Microinjection of SPN-3 antibody into taxol-treated mitotic PtK2 cells causes disruption of the asters as judged by tubulin staining of the same cells. Finally, SPN antigen extracted in soluble form from synchronized mitotic HeLa cells binds to, and sediments with, pig brain microtubules stabilized by taxol. This association of SPN antigen with microtubules is partially dissociated by 0.5 M NaCl but not by 5 mM ATP. Thus SPN antigen binds to microtubules in vitro and seems to act as a microtubular minus-end organizer in mitotic cells in vivo.

scholarly journals Biogenesis of the rat hepatocyte plasma membrane in vivo: comparison of the pathways taken by apical and basolateral proteins using subcellular fractionation.

1987 ◽  
Vol 105 (3) ◽  
pp. 1241-1251 ◽  
Author(s):  
J R Bartles ◽  
H M Feracci ◽  
B Stieger ◽  
A L Hubbard
Keyword(s):  
Plasma Membrane ◽  
Membrane Fraction ◽  
Subcellular Fractionation ◽  
Aminopeptidase N ◽  
Rat Hepatocyte ◽  
Dipeptidylpeptidase Iv ◽  
Plasma Membrane Fraction ◽  
Apical Domain ◽  
Basolateral Plasma Membrane

We have used pulse-chase metabolic radiolabeling with L-[35S]methionine in conjunction with subcellular fractionation and specific protein immunoprecipitation techniques to compare the posttranslational transport pathways taken by endogenous domain-specific integral proteins of the rat hepatocyte plasma membrane in vivo. Our results suggest that both apical (HA 4, dipeptidylpeptidase IV, and aminopeptidase N) and basolateral (CE 9 and the asialoglycoprotein receptor [ASGP-R]) proteins reach the hepatocyte plasma membrane with similar kinetics. The mature molecular mass form of each of these proteins reaches its maximum specific radioactivity in a purified hepatocyte plasma membrane fraction after only 45 min of chase. However, at this time, the mature radiolabeled apical proteins are not associated with vesicles derived from the apical domain of the hepatocyte plasma membrane, but instead are associated with vesicles which, by several criteria, appear to be basolateral plasma membrane. These vesicles: (a) fractionate like basolateral plasma membrane in sucrose density gradients and in free-flow electrophoresis; (b) can be separated from the bulk of the likely organellar contaminants, including membranes derived from the late Golgi cisternae, transtubular network, and endosomes; (c) contain the proven basolateral constituents CE 9 and the ASGP-R, as judged by vesicle immunoadsorption using fixed Staphylococcus aureus cells and anti-ASGP-R antibodies; and (d) are oriented with their ectoplasmic surfaces facing outward, based on the results of vesicle immunoadsorption experiments using antibodies specific for the ectoplasmic domain of the ASGP-R. Only at times of chase greater than 45 min do significant amounts of the mature radiolabeled apical proteins arrive at the apical domain, and they do so at different rates. Approximate half-times for arrival are in the range of 90-120 min for aminopeptidase N and dipeptidylpeptidase IV whereas only 15-20% of the mature radiolabeled HA 4 associated with the hepatocyte plasma membrane fraction has become apical even after 150 min of chase. Our results suggest a mechanism for hepatocyte plasma membrane biogenesis in vivo in which all integral plasma membrane proteins are shipped first to the basolateral domain, followed by the specific retrieval and transport of apical proteins to the apical domain at distinct rates.

scholarly journals Oleanolic acid inhibits the proliferation of Hela cells in cervical cancer by regulating the ACSL4 ferroptosis signaling pathway

2020 ◽  
Author(s):  
Xiaofei Jiang ◽  
Mingqing Shi ◽  
Miao Sui ◽  
Yizhen Yuan ◽  
Shuang Zhang ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Hela Cell ◽  
Cancer Cells ◽  
Oleanolic Acid ◽  
Hela Cells ◽  
Proliferation Capacity ◽  
Cervical Cancer Cells ◽  
Related Proteins

Abstract Background: Cervical cancer continues to be the leading cause of cancer deaths among women worldwide. Oleanolic acid (OA) is a naturally occurring substance found in the leaves, fruits, and rhizomes of plants that has anti-cancer activity. Methods: We used tumor-bearing mice as the animal model and Hela cell as cell models. Western blot was used for detecting the expression of proteins in ferroptosis related proteins acyl-CoA synthase long-chain family member 4 (ACSL4), ferritin heavy chain (FTH1), transferrin receptor (TfR1) and glutathione peroxidase 4 (GPX4) in vivo and in vitro. MTT and EdU was for the detection of the viability of Hela cells. Results: In vivo experiments showed that OA significantly reduced the size and mass of cervical cancer tumors. In vitro experiments showed that OA significantly reduced the viability and proliferation capacity of Hela cells. In both in vivo and in vitro assays, OA increased the level of oxidative stress and Fe2+ content, and increased the expression of ferroptosis related proteins. We found high expression of ACSL4 in both xenograft models and cervical carcinoma cells. Meanwhile, knockdown of ACSL4 expression using shRNA in cervical cancer cells significantly increased cell viability and proliferation. In addition, decreased ROS levels and GPX4 were detected in ACSL4 knockdown cervical cancer cells, suggesting that ACSL4 inhibition may contribute to the reduction of ferroptosis within Hela cells and thus improve Hela cell survival. Conclusion: Promotion of ACSL4 dependent ferroptosis through OA may be an effective approach to treat cervical cancer.

scholarly journals Zirconia Nanoparticles Induce HeLa Cell Death Through Mitochondrial Apoptosis and Autophagy Pathways Mediated by ROS

2021 ◽  
Vol 9 ◽  
Author(s):  
Yinghui Shang ◽  
Qinghai Wang ◽  
Jian Li ◽  
Haiting Liu ◽  
Qiangqiang Zhao ◽  
...  
Keyword(s):  
Cell Death ◽  
Hela Cell ◽  
Hela Cells ◽  
Mitochondrial Apoptosis ◽  
Ki 67 ◽  
Transmission Electron ◽  
Anti Tumor Activity ◽  
Zirconia Nanoparticles

Zirconia nanoparticles (ZrO2 NPs) are commonly used in the field of biomedical materials, but their antitumor activity and mechanism is unclear. Herein, we evaluated the anti-tumor activity of ZrO2 NPs and explored the anti-tumor mechanism. The results of in vitro and in vivo experiments showed that the level of intracellular reactive oxygen species (ROS) in HeLa cells was elevated after ZrO2 NPs treatment. Transmission electron microscopy (TEM) showed that after treatment with ZrO2 NPs, the mitochondria of HeLa cells were swollen, accompanied with the induction of autophagic vacuoles. In addition, flow cytometry analysis showed that the apoptotic rate of HeLa cells increased significantly by Annexin staining after treatment with ZrO2 NPs, and the mitochondrial membrane potential (MMP) was reduced significantly. The proliferation of HeLa cells decreased as indicated by reduced Ki-67 labeling. In contrast, TUNEL-positive cells in tumor tissues increased after treatment with ZrO2 NPs, which is accompanied by increased expression of mitochondrial apoptotic proteins including Bax, Caspase-3, Caspase-9, and Cytochrome C (Cyt C) and increased expression of autophagy-related proteins including Atg5, Atg12, Beclin-1, and LC3-II. Treating HeLa cells with N-acetyl-L-cysteine (NAC) significantly reduced ROS, rate of apoptosis, MMP, and in vivo anti-tumor activity. In addition, apoptosis- and autophagy-related protein expressions were also suppressed. Based on these observations, we conclude that ZrO2 NPs induce HeLa cell death through ROS mediated mitochondrial apoptosis and autophagy.

scholarly journals Ganglioside glycosyltransferases and newly synthesized gangliosides are excluded from detergent-insoluble complexes of Golgi membranes

2004 ◽  
Vol 377 (3) ◽  
pp. 561-568 ◽  
Author(s):  
Pilar M. CRESPO ◽  
Adolfo R. ZURITA ◽  
Claudio G. GIRAUDO ◽  
Hugo J. F. MACCIONI ◽  
Jose L. DANIOTTI
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Secretory Pathway ◽  
Chinese Hamster ◽  
Galactosyl Transferase ◽  
Golgi Membranes ◽  
Cell Clones ◽  
Triton X ◽  
Ganglioside Species

GEM (glycosphingolipid-enriched microdomains) are specialized detergent-resistant domains of the plasma membrane in which some gangliosides concentrate. Although genesis of GEM is considered to occur in the Golgi complex, where the synthesis of gangliosides also occurs, the issue concerning the incorporation of ganglioside species into GEM is still poorly understood. In this work, using Chinese hamster ovary K1 cell clones with different glycolipid compositions, we compared the behaviour with cold Triton X-100 solubilization of plasma membrane ganglioside species with the same species newly synthesized in Golgi membranes. We also investigated whether three ganglioside glycosyltransferases (a sialyl-, a N-acetylgalactosaminyl- and a galactosyl-transferase) are included or excluded from GEM in Golgi membranes. Our data show that an important fraction of plasma membrane GM3, and most GD3 and GT3, reside in GEM. Immunocytochemical examination of GD3-expressing cells showed GD3 to be distributed as cold-detergent-resistant patches in the plasma membrane. These patches did not co-localize with a glycosylphosphatidylinositol-anchored protein used as GEM marker, indicating a heterogeneous composition of plasma membrane GEM. In Golgi membranes we were unable to find evidence for GEM localization of either ganglioside glycosyltransferases or newly synthesized gangliosides. Since the same ganglioside species appear in plasma membrane GEM, it was concluded that in vivo nascent GD3, GT3 and GM3 segregate from their synthesizing transferases and then enter GEM. This latter event could have taken place shortly after synthesis in the Golgi cisternae, along the secretory pathway and/or at the cell surface.

Reactivation of euglenoid movement and flagellar beating in detergent-extracted cells of Astasia longa: different mechanisms of force generation are involved

1986 ◽  
Vol 80 (1) ◽  
pp. 75-89
Author(s):  
T. Suzaki ◽  
R.E. Williamson
Keyword(s):  
Plasma Membrane ◽  
Force Generation ◽  
Free Calcium ◽  
Cell Models ◽  
Calcium Treatment ◽  
Astasia Longa ◽  
Flagellar Membrane ◽  
Triton X ◽  
Euglenoid Movement

Detergent-extracted cell models of the euglenoid flagellate, Astasia longa, were obtained that rounded-up on addition of calcium. Treatment with 4% Triton X-100 and Nonidet P-40 removed the flagellar membrane, all membranous structures inside the cell body and the plasma membrane at groove regions of the cell surface. Maximum rounding-up was induced when the concentration of free calcium was raised to greater than or equal to 10(−7) M, and ATP strongly enhanced this response. The ionic requirements and sensitivity to vanadate were different from those for the reactivation of flagellar movement. The results suggest that the mechanism of force generation is different from the dynein-based system of the flagellum and that a rise in cytoplasmic free Ca2+ concentration might cause euglenoid movement in vivo. The mechanism of euglenoid movement is discussed in relation to other protozoan motile systems.

Ligand Binding Characteristics of a Glycosylphosphatidyl Inositol Membrane-Anchored HeLa Cell Folate Receptor Epitope-Related to Human Milk Folate Binding Protein

2000 ◽  
Vol 20 (2) ◽  
pp. 109-118 ◽  
Author(s):  
Jan Holm ◽  
Steen Ingemann Hansen ◽  
Mimi Høier-Madsen ◽  
Lars Korsbaek ◽  
Heidi Beckmann ◽  
...  
Keyword(s):  
Human Milk ◽  
Hela Cell ◽  
Hela Cells ◽  
Binding Protein ◽  
Folate Receptor ◽  
Hill Coefficient ◽  
Complete Suppression ◽  
Membrane Anchor ◽  
Antigenic Properties ◽  
Triton X

The folate receptor (FR) in HeLa cells was characterized as to ligandbinding mechanism, antigenic properties and membrane anchor in order toobtain information to be used for the design of biological agentstargeting FR in malignant tumors. The receptor displayed the followingbinding characteristics in equilibrium dialysis experiments(37°C, pH 7.4) with [3H] folate: a high-affinity type of bindingthat exhibited positive cooperativity with a Hill coefficient >1.0and an upward convex Scatchard plot, a slow radioligand dissociation atpH 7.4 becoming rapid at pH 3.5 and inhibition in the presence of otherfolates. The molecular size of the receptor was 100 kDa on gel filtrationwith Triton X-100, or similar to that of high molecular weight human milkfolate binding protein (FBP). The latter protein represents a 25 kDamolecule which equipped with a hydrophobic glycosylphosphatidylinositol (GPI) membrane anchor susceptible to cleavage byphosphatidylinositol specific phospholipase C (PI-PLC) formsmicelles of 100 kDa size with Triton X-100. The HeLa cell FRimmunoreacted with antibodies against purified human milk FBP inELISA, and in a fluorescence activated cell sorting system, whereHeLa cells exposed to increasing concentrations of antibody showed adose-dependent response. Exposure to PI-PLC decreased the fraction ofimmunolabeled cells indicating a linkage of FR to cell membranes by aGPI anchor. HeLa cells incubated with radiofolate showed a continuousuptake with time, however, with a complete suppression of uptake in thepresence of an excess of cold folate. Prewash of cells at acidic pH toremove endogenous folate increased the uptake. Binding and uptake of [3H]folate was increased in cells grown in a folate-deprived medium. The HeLaFR seems to be epitope related to human milk FBP.

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