scholarly journals Collagen can modulate cell interactions with fibronectin.

1985 ◽  
Vol 101 (2) ◽  
pp. 386-394 ◽  
Author(s):  
K Nagata ◽  
M J Humphries ◽  
K Olden ◽  
K M Yamada
Keyword(s):  
Cell Spreading ◽  
Inhibitory Effect ◽  
The Other ◽  
Baby Hamster Kidney ◽  
Cell Surfaces ◽  
Cell Binding ◽  
Bhk Cells ◽  
Soluble Collagen ◽  
D Cell ◽  
Direct Attachment

We have examined the effects of soluble collagen on the function of fibronectin in baby hamster kidney (BHK) cells. Collagen and its purified alpha1(l) chain noncompetitively inhibited cell spreading on substrates precoated with fibronectin or a 75,000-D cell-binding fragment of fibronectin. Neither preincubation of cells with collagen followed by washing nor the addition of collagen to previously spread cells had any inhibitory effect on cell spreading, which indicates a requirement for the concurrent presence of collagen during the process of spreading. Treatment of collagen or alpha1(l) chain with collagenase abolished the inhibitory effect on fibronectin-mediated cell spreading. However, direct attachment of BHK cells to fibronectin-coated or 75,000-D fragment-coated substrates was not inhibited by collagen or by the alpha1(l) chain. Moreover, the binding of [3H]fibronectin or the 3'-75,000-D fragment to cell surfaces was not inhibited by the presence of soluble collagen, whereas soluble fibronectin inhibited binding. Although the binding of [3H]fibronectin-coated beads to BHK cell surfaces was also not inhibited by collagen, the phagocytosis of such beads was inhibited by the presence of collagen. On the other hand, soluble fibronectin partially inhibited the binding of fibronectin-coated beads but did not inhibit phagocytosis of the beads that did bind. The mechanism of the inhibition of fibronectin function by collagen and the possible interactions of two different kinds of receptors on the cell surface are discussed.

Cell adhesion and phagocytosis promoted by monoclonal antibodies not directed against fibronectin receptors

1988 ◽  
Vol 90 (2) ◽  
pp. 201-214 ◽  
Author(s):  
F. Grinnell ◽  
C.H. Ho ◽  
T.L. Tuan
Keyword(s):  
Monoclonal Antibodies ◽  
Cell Adhesion ◽  
Binding Sites ◽  
Cell Spreading ◽  
The Other ◽  
Immunofluorescence Staining ◽  
Baby Hamster Kidney ◽  
Bhk Cells ◽  
Reducing Conditions ◽  
Latex Beads

In this report we describe cell adhesion and phagocytosis promoted by two monoclonal antibodies that were selected for immunofluorescence staining of non-permeabilized baby hamster kidney (BHK) cells. Anti-BHK1 staining was heaviest along cell margins, whereas anti-BHK2 staining was continuous along cell margins. Neither antibody stained elongated plaque structures such as were observed when cells were reacted with antibodies to fibronectin (FN) receptors. The monoclonal antibodies functioned as adhesion ligands in four different assays: attachment to culture dishes, spreading, binding of latex beads and phagocytosis. Anti-BHK1 and anti-BHK2 promoted attachment to culture dishes similarly, but anti-BHK2 was more effective at promoting cell spreading. Antibody-promoted cell spreading was inhibited by the peptides Ser-Asp-Gly-Arg and Gly-Arg-Gly-Asp-Ser-Pro but not by other, related, peptides tested. The monoclonal antibodies also promoted binding of latex beads, and the bead binding sites were motile, on the basis of their ‘capping’ response. Nevertheless, anti-BHK2 beads were phagocytosed by cells 5- to 20-fold more efficiently than anti-BHK1 beads. The binding sites for anti-BHK1 and anti-BHK2 were characterized by immunoprecipitation experiments. Anti-BHK1 binding sites contained 50K (K = 10(3) Mr) and 88K components under non-reducing conditions that migrated as a 51/53K doublet and a 93K component under reducing conditions. On the other hand, anti-BHK2 binding sites contained 88K and 110K components under non-reducing conditions that shifted to apparent 107K and 128K values when measured under reducing conditions.

scholarly journals Thiol-sensitive sites in cell adhesion. Decreased entry of SH-binding reagents into attached BHK cells

1982 ◽  
Vol 208 (2) ◽  
pp. 473-478 ◽  
Author(s):  
D D McAbee ◽  
F Grinnell
Keyword(s):  
Cell Adhesion ◽  
Small Molecules ◽  
Cell Spreading ◽  
The Other ◽  
Bhk Cells ◽  
Sh Groups ◽  
Nitrobenzoic Acid ◽  
Cytoplasmic Proteins ◽  
Adhesion Process ◽  
Suspended Cells

Studies were carried out to learn more about the critical SH groups involved in cell spreading. Pretreatment of suspended baby hamster kidney (BHK) cells with 3 mM-iodoacetate or iodoacetamide for 10 min at 4 degrees C completely inhibited the ability of the cells to spread on fibronectin-coated substrata. If, however, BHK cells were permitted to attach and spread before being treated with the SH-binding reagents, and then harvested by trypsinization and assayed for spreading on fibronectin-coated substrata, there was no inhibition of cell spreading. The extent of prior attachment required before the cells became insensitive to the SH-binding reagents was tested and was found to occur early during the cell adhesion process, before any cell spreading was observed. In analytical experiments, there did not appear to be any difference in the total number of SH groups between suspended or spread cells as determined with 5,5′-dithiobis-(2-nitrobenzoic acid). The uptake of radiolabelled iodoacetate into intact spread cells, however, was found to be 3.5 times less than that found with suspended cells. On the other hand, the distribution of incorporated radioactivity into suspended and spread cells was similar. Most of the radioactivity (approximately 70%) was incorporated into small molecules (e.g. glutathione and cysteine), less (approximately 20%) was incorporated into cytoplasmic proteins, and the least incorporation (approximately 10%) was into the cell cytoskeleton. The data are interpreted to indicate there is a decreased permeability of spread cells to the SH-binding reagents.

The apparent infection of NA-C1300 cell cultures by nucleocapsid material of the Canadian Arctic strain of rabies virus

1989 ◽  
Vol 35 (8) ◽  
pp. 811-813
Author(s):  
W. A. Webster ◽  
K. M. Charlton
Keyword(s):  
Rabies Virus ◽  
Cell Cultures ◽  
Virus Strain ◽  
Canadian Arctic ◽  
The Other ◽  
Baby Hamster Kidney ◽  
Bhk Cells ◽  
Murine Neuroblastoma ◽  
Other Hand

Murine neuroblastoma (NA-C1300) and baby hamster kidney (BHK-21/C13) cell cultures were infected with the Canadian Arctic strain of rabies virus. Subcultures were passed following incubation for 3 to 4 days at 35 °C. The supernatant fluids from the BHK cultures demonstrated increasing infectivity in both NA and BHK cells concomitantly with an increase in the number of parent cells staining with an anti-glycoprotein stain. On the other hand, the supernatant fluids from the NA cultures initially showed higher infectivity in NA cells than in BHK cells. This feature was related to a low production of glycoprotein-staining cells in the parent NA cultures. The reduction of infectivity in NA cells of some NA supernatant fluids (and brain suspensions) by anti-nucleoprotein antibodies suggests that nucleocapsid material is, in some manner, capable of infecting NA cells. Infectivity of this virus strain in experimental mice is also related to the production of glycoprotein and may not be correlated with the degree of infection in NA cell cultures.Key words: rabies, nucleocapsid, infection, cells.

scholarly journals Effect of Potassium Channel Modulators on Morphine Withdrawal in Mice

2010 ◽  
Vol 4 ◽  
pp. SART.S6211 ◽  
Author(s):  
Vikas Seth ◽  
Mushtaq Ahmad ◽  
Prerna Upadhyaya ◽  
Monika Sharma ◽  
Vijay Moghe
Keyword(s):  
Potassium Channel ◽  
Withdrawal Syndrome ◽  
Channel Blocker ◽  
Inhibitory Effect ◽  
Morphine Withdrawal ◽  
The Other ◽  
Opioid Antagonist ◽  
Potassium Channel Openers ◽  
Potassium Channel Modulators ◽  
Withdrawal Signs

The present study was conducted to investigate the effect of potassium channel openers and blockers on morphine withdrawal syndrome. Mice were rendered dependent on morphine by subcutaneous injection of morphine; four hours later, withdrawal was induced by using an opioid antagonist, naloxone. Mice were observed for 30 minutes for the withdrawal signs ie, the characteristic jumping, hyperactivity, urination and diarrhea. ATP-dependent potassium (K+ATP) channel modulators were injected intraperitoneally (i.p.) 30 minutes before the naloxone. It was found that a K+ATP channel opener, minoxidil (12.5–50 mg/kg i.p.), suppressed the morphine withdrawal significantly. On the other hand, the K+ATP channel blocker glibenclamide (12.5–50 mg/kg i.p.) caused a significant facilitation of the withdrawal. Glibenclamide was also found to abolish the minoxidil's inhibitory effect on morphine withdrawal. The study concludes that K+ATP channels play an important role in the genesis of morphine withdrawal and K+ATP channel openers could be useful in the management of opioid withdrawal. As morphine opens K+ATP channels in neurons, the channel openers possibly act by mimicking the effects of morphine on neuronal K+ currents.

Functional partitioning of beta1 integrins revealed by activating and inhibitory mAbs

1997 ◽  
Vol 110 (21) ◽  
pp. 2647-2659 ◽  
Author(s):  
M.T. Cruz ◽  
C.L. Dalgard ◽  
M.J. Ignatius
Keyword(s):  
Cell Surface ◽  
Actin Cytoskeleton ◽  
Dermal Fibroblasts ◽  
The Other ◽  
Embryonic Chick ◽  
Cell Surfaces ◽  
Double Labeling ◽  
Focal Contacts ◽  
Functional Partitioning ◽  
Discrete Populations

Integrins exist in different activation states on the surfaces of cells. Addition of the proper signal, ligand, or antibody can alter the activation state of these molecules. We report here the identification of two immunocytochemically distinct populations of beta1 integrins on fixed embryonic chick dermal fibroblasts. One population, recognized by the integrin activating mAb TASC, localizes to discrete regions of the cell, most likely focal contacts. These integrins co-localize with other proteins, such as vinculin and F-actin, and their retention at these sites is dependent on the actin cytoskeleton. The other population, identified with the inhibitory mAb W1B10, is more evenly distributed throughout the cell surface, and its pattern remains unchanged after disruption of the actin cytoskeleton. Double labeling experiments using Fab fragments of TASC alongside whole W1B10 IgG revealed non-overlapping staining patterns. These results show that it is possible to visualize and study discrete populations of integrins on cell surfaces using two different antibodies. We hypothesize that these antibodies report differences in the distribution of receptors in two different states. A model is proposed describing the ligand independent recruitment of integrins based on these findings and results from other labs.

C-terminal heparin-binding domain of fibronectin regulates integrin-mediated cell spreading but not the activation of mitogen-activated protein kinase

2001 ◽  
Vol 360 (1) ◽  
pp. 239-245 ◽  
Author(s):  
Jungyean KIM ◽  
Innoc HAN ◽  
Yeonhee KIM ◽  
Seungin KIM ◽  
Eok-Soo OH
Keyword(s):  
Cell Spreading ◽  
Binding Domain ◽  
Mitogen Activated Protein Kinase ◽  
Heparin Binding ◽  
Cell Binding ◽  
Rat Embryo ◽  
Mapk Activation ◽  
Mitogen Activated Protein ◽  
Heparin Binding Domain ◽  
Cell Binding Domain

Fibronectin (FN) stimulates multiple signalling events including mitogen-activated protein kinase (MAPK) activation. During cell spreading, both the cell-binding domain and the C-terminal heparin-binding domain (HepII) of FN co-operatively regulate cytoskeleton organization. However, in comparison with the large number of studies on the functions of cell-binding domain, there is little information about the role of HepII. We therefore investigated the effect of HepII on integrin-mediated cell spreading and adhesion on FN and MAPK activation. In contrast with cells on FN substrates, rat embryo fibroblasts on FN120, which lacks HepII, were less spread, had weaker adhesion to FN and failed to form focal adhesions and actin stress fibres. Phosphotyrosine was present in the focal contacts of rat embryo fibroblasts on FN within 30min but was absent from cells on FN120. Overall, tyrosine phosphorylation was much less in cell lysates from cells on FN120, with decreased phosphorylation of focal adhesion kinase (‘pp125FAK’) on tyrosine-397, implying additional regulation of tyrosine phosphorylation by HepII. Nevertheless, adhesion-mediated MAPK activity was similar in cells on FN and on FN120. Furthermore, cells spread on FN and on FN120 substrates showed similar MAPK activation in response to treatment with epidermal growth factor and with platelet-derived growth factor. Consistently, overexpression of syndecan-4, which binds to HepII, enhanced cell spreading and adhesion on FN but did not affect integrin-mediated MAPK activation. We therefore conclude that both HepII and syndecan-4 regulate integrin-mediated cell spreading but not MAPK activation.

scholarly journals Cycles of autoubiquitination and deubiquitination regulate the ERAD ubiquitin ligase Hrd1

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Brian G Peterson ◽  
Morgan L Glaser ◽  
Tom A Rapoport ◽  
Ryan D Baldridge
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Ubiquitin Ligase ◽  
Ground State ◽  
Inhibitory Effect ◽  
The Other ◽  
Misfolded Proteins ◽  
Deubiquitinating Enzyme ◽  
Transmembrane Segment

Misfolded proteins in the lumen of the endoplasmic reticulum (ER) are retrotranslocated into the cytosol and polyubiquitinated before being degraded by the proteasome. The multi-spanning ubiquitin ligase Hrd1 forms the retrotranslocation channel and associates with three other membrane proteins (Hrd3, Usa1, Der1) of poorly defined function. The Hrd1 channel is gated by autoubiquitination, but how Hrd1 escapes degradation by the proteasome and returns to its inactive ground state is unknown. Here, we show that autoubiquitination of Hrd1 is counteracted by Ubp1, a deubiquitinating enzyme that requires its N-terminal transmembrane segment for activity towards Hrd1. The Hrd1 partner Hrd3 serves as a brake for autoubiquitination, while Usa1 attenuates Ubp1’s deubiquitination activity through an inhibitory effect of its UBL domain. These results lead to a model in which the Hrd1 channel is regulated by cycles of autoubiquitination and deubiquitination, reactions that are modulated by the other components of the Hrd1 complex.

scholarly journals 2,4-EPIBRASSIONOLIDE ACTIVATES PRIMING RESISTANCE AGAINST RHIZOPUS STOLONIFER INFECTION IN PEACH FRUIT

2020 ◽  
Vol 49 (2) ◽  
pp. 135-143
Author(s):  
C.H. Li ◽  
M.Y. Du ◽  
K.T. Wang
Keyword(s):  
Fungal Infection ◽  
Inhibitory Effect ◽  
The Other ◽  
Antifungal Compounds ◽  
Rhizopus Stolonifer ◽  
Peach Fruit ◽  
Direct Inhibitory Effect ◽  
Potential Alternative ◽  
Direct Toxicity

This study was conducted to assess the effects of 2,4-epibrassionolide (EBR) on mold decay caused by Rhizopus stolonifer and its capability to activate biochemical defense reactions in postharvest peaches. The treatment of EBR at 5 μM possessed the optimum effectiveness on inhibiting the Rhizopus rot in peach fruit among all treatments. The EBR treatment significantly up-regulated the expression levels of a set of defense-related enzymes and PR genes that included PpCHI, PpGns1, PpPAL, PpNPR1, PpPR1 and PpPR4 as well as led to an enhancement for biosynthesis of phenolics and lignins in peaches during the incubation at 20 °C. Interestingly, the EBR-treated peaches exhibited more striking expressions of PR genes and accumulation of antifungal compounds upon inoculation with the pathogen, indicating a priming defense could be activated by EBR. On the other hand, 5 μM EBR exhibited direct toxicity on fungal proliferation of R. stolonifer in vitro. Thus, we concluded that 5 μM EBR inhibited the Rhizopus rot in peach fruit probably by a direct inhibitory effect on pathogen growth and an indirect induction of a priming resistance. These findings provided a potential alternative for control of fungal infection in peaches during the postharvest storage.

Effect of thiocarbamate, urea, and uracil herbicides on lipid metabolism in groundnut (Arachis hypogaea) leaves

1990 ◽  
Vol 68 (2) ◽  
pp. 567-573 ◽  
Author(s):  
R. Rajasekharan ◽  
P. S. Sastry
Keyword(s):  
Lipid Metabolism ◽  
Arachis Hypogaea ◽  
Acid Synthesis ◽  
Inhibitory Effect ◽  
Significant Inhibition ◽  
The Other ◽  
Acetate Incorporation ◽  
Phosphatidic Acid Phosphatase ◽  
Choline Incorporation ◽  
Plant Lipids

The effect of thiocarbamates (S-ethyldipropylthiocarbamate and diallate), substituted ureas (monuron and diuron), and uracils (bromacil and terbacil) on lipid metabolism in groundnut (Arachis hypogaea) leaves was investigated under nonphotosynthetic conditions. The uptake of [1-14C]acetate by leaf disks was inhibited by the thiocarbamates and marginally by the substituted ureas, but not by the uracil herbicides. The uptake of [methyl-14C]choline was inhibited to a lesser extent by thiocarbamates, while the other herbicides showed a slight stimulation. The thiocarbamates almost completely inhibited uptake of [32P]orthophosphate at 1.0 mM concentration, while diuron and terbacil showed significant inhibition. [1-14C]Acetate incorporation into lipids was inhibited only by diallate. [methyl-14C]Choline incorporation into the choline phosphoglycerides was inhibited by diallate, diuron, and bromacil. The incorporation of [32P]orthophosphate into phospholipids was substantially inhibited (over 90% at 1.0 mM) by the thiocarbamates, but not by the other herbicides. [35S]Sulfate incorporation into sulfoquinovosyl diglycerides was markedly inhibited only by the thiocarbamates. Fatty acid synthesis by isolated chloroplasts was inhibited 40–85% by thiocarbamates, substituted ureas, and bromacil, but not by terbacil. The inhibitory effect of the urea derivatives was reversible, but that of thiocarbamates was irreversible. sn-Glycerol-3-phosphate acyltransferase(s) of the chloroplast and microsomal fractions were profoundly inhibited by thiocarbamates, but not by the other two groups of herbicides. Phosphatidic acid phosphatase was insensitive to all the herbicides tested.Key words: herbicides, thiocarbamates, substituted ureas, uracils, effects on plant lipids.

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