Enhancement of differentiation of cultured adipogenic cells (TA1) by pertussis toxin

1992 ◽  
Vol 70 (8) ◽  
pp. 650-655 ◽  
Author(s):  
Osamu Shinohara ◽  
Yoh-Ichi Murata ◽  
Makoto Shimizu
Keyword(s):  
G Proteins ◽  
Pertussis Toxin ◽  
Adipocyte Differentiation ◽  
Dibutyryl Camp ◽  
Gtp Binding ◽  
Dose Dependent Fashion ◽  
Adipose Conversion ◽  
Adipocyte Cell ◽  
Dose Dependent

Differentiation of adipocytes is controlled by a variety of hormones and growth factors. To investigate the possible role of GTP-binding proteins (G proteins) in the process of adipose conversion, we studied the effect of pertussis toxin on differentiation of the fibroblast/adipocyte cell line (TA1). Pertussis toxin potentiated dexamethasone- and indomethacin-induced adipocyte differentiation in a time- and dose-dependent fashion. Addition of dibutyryl cAMP or forskolin inhibited adipose conversion, indicating that an abolishment of inhibitory control of adenylate cyclase is not responsible for the action of pertussis toxin. The B oligomer of the toxin did not mimic the effect of the holotoxin. Pertussis toxin catalyzed ADP-ribosylation of 40 000 molecular mass protein of the membrane fraction was dose-dependently inhibited by the pretreatment of the cells with the toxin. These results indicate the possible involvement of pertussis toxin-sensitive G proteins in adipogenesis.Key words: adipose tissue, pertussis toxin, GTP-binding protein.

Semicarbazide-sensitive amine oxidase activation promotes adipose conversion of 3T3-L1 cells

2001 ◽  
Vol 358 (2) ◽  
pp. 335-342 ◽  
Author(s):  
Nathalie MERCIER ◽  
Marthe MOLDES ◽  
Khadija EL HADRI ◽  
Bruno FÈVE
Keyword(s):  
Potential Role ◽  
Adipocyte Differentiation ◽  
Amine Oxidase ◽  
Monoamine Oxidase Inhibitor ◽  
Oxidase Inhibitor ◽  
Dependent Manner ◽  
Adipose Conversion ◽  
Adipose Tissue Development ◽  
Dose Dependent

Semicarbazide-sensitive amine oxidase (SSAO) is an amine oxidase related to the copper-containing amine oxidase family. The tissular form of SSAO is located at the plasma membrane, and is mainly expressed in vascular smooth muscle cells and adipocytes. Recent studies have suggested that SSAO could activate glucose transport in fat cells. In the present work, we investigated the potential role of a chronic SSAO activation on adipocyte maturation of the 3T3-L1 pre-adipose cell line. Exposure of post-confluent 3T3-L1 pre-adipocytes to methylamine, a physiological substrate of SSAO, promoted adipocyte differentiation in a time- and dose-dependent manner. This effect could be related to SSAO activation, since it was antagonized in the presence of the SSAO inhibitor semicarbazide, but not in the presence of the monoamine oxidase inhibitor pargyline. In addition, methylamine-induced adipocyte maturation was mimicked by 3T3-L1 cell treatment with other SSAO substrates. Finally, the large reversion of methylamine action by catalase indicated that hydrogen peroxide generated by SSAO was involved, at least in part, in the modulation of adipocyte maturation. Taken together, our results suggest that SSAO may contribute to the control of adipose tissue development.

scholarly journals Erratum

1991 ◽  
Vol 11 (4) ◽  
pp. 706-706
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Equilibrium State ◽  
Rat Brain ◽  
G Proteins ◽  
Pertussis Toxin ◽  
Adp Ribosylation ◽  
Gtp Binding ◽  
Reconstituted System ◽  
Α Subunits

Ischemia of Rat Brain Decreases Pertussis Toxin-Catalyzed [32P] ADP Ribosylation of GTP-Binding Proteins (Gi1 and G0) in Membranes Katsunobu Takenaka, Yasunori Kanaho, Koh-ichi Nagata, Noboru Sakai, Hiromu Yamada, Yoshinori Nozawa [ Originally published in Journal of Cerebral Blood Flow and Metabolism 1991;11:155–160] On page 158 of the above, arrows were erroneously deleted from the equation in the following passage: Heterotrimers of G proteins that bind GDP to α subunits seem to be the preferred substrates for PTcatalyzed ADP ribosylation since guanine nucleotides (GDP and GTP) and 13'Y subunits stimulate ADP ribosylation in the reconstituted system and in membranes (Tsai et aI., 1984). These results indicate that the G proteins may exist at the equilibrium state as shown below: This omission was the result of a typesetting error, which the publisher regrets.

scholarly journals Increased intracellular cyclic adenosine monophosphate inhibits T lymphocyte-mediated cytolysis by two distinct mechanisms.

1988 ◽  
Vol 167 (6) ◽  
pp. 1963-1968 ◽  
Author(s):  
L S Gray ◽  
J Gnarra ◽  
E L Hewlett ◽  
V H Engelhard
Keyword(s):  
Cholera Toxin ◽  
T Lymphocyte ◽  
Pertussis Toxin ◽  
Target Cell ◽  
Cyclic Adenosine Monophosphate ◽  
Second Messenger ◽  
Adenosine Monophosphate ◽  
Dose Dependent Fashion ◽  
Dose Dependent ◽  
Stimulation Of

Cholera toxin (CT), but not pertussis toxin (PT), treatment of cloned murine CTL inhibited target cell lysis in a dose-dependent fashion. The effects of CT were mimicked by forskolin and cyclic adenosine monophosphate (cAMP) analogues. Inhibition of cytotoxicity by CT and cAMP analogs was mediated in part by attenuation of conjugate formation. Additionally, both CT and cAMP analogs blocked the increase in intracellular Ca2+ induced by stimulation of the TCR complex by mAbs. These findings indicate that cAMP inhibits the activity of CTL by two distinct mechanisms and suggests a role for this second messenger in CTL-mediated cytolysis.

scholarly journals Critical Role of Pertussis Toxin Sensitive G Proteins in the Activation of TRPC4 and TRPC5 Channels

2010 ◽  
Vol 98 (3) ◽  
pp. 326a-327a
Author(s):  
Rui Xiao ◽  
Jinbin Tian ◽  
Jisen Tang ◽  
Alexander V. Zholos ◽  
Michael X. Zhu
Keyword(s):  
G Proteins ◽  
Pertussis Toxin ◽  
Critical Role ◽  
Trpc5 Channels

Induction of cell—cell adhesion by monovalent antibodies in a germ cell culture

Development ◽  
1985 ◽  
Vol 90 (1) ◽  
pp. 211-222
Author(s):  
Wai Chang Ho ◽  
Kathleen B. Bechtol
Keyword(s):  
Monoclonal Antibodies ◽  
Cell Adhesion ◽  
Germ Cell ◽  
Germ Cells ◽  
Antigen Expression ◽  
Fab Fragment ◽  
Cell Age ◽  
Dose Dependent Fashion ◽  
Dose Dependent

Four monoclonal antibodies, XT-I, MT-23, MT-24 and MT-29, that bind the XT-1-differentiation-antigen of male germ cells have been used to investigate the biological role of the XT-1-molecule of germ cells in short-term primary culture. Cultures from 10 days postpartum mice demonstrate increasing numbers of antigen-positive germ cells and increased antigen expression per cell with succeeding days of culture. Treatment of the antigen-positive cultures with three of the monoclonal antibodies, XT-I, MT-23 and MT-24, increases germ cell-germ cell adhesion in a dose-dependent fashion. Treatment with the fourth monoclonal antibody, MT-29, does not induce cell adhesion. The monovalent, Fab fragment of XT-I-antibody also elicits tight cell adhesion, thus ruling out antibody cross linking of molecules or cells. Saturating or near saturating amounts of the positive antibodies are required to produce adhesion, a result consistent with perturbation of a function that is performed by the sum of action of many of the XT-1-molecules on the cell. The ability of germ cells to undergo antibody-elicited tight adhesion is dependent on germ cell age and/or XT-1-antigen concentration. We hypothesize that the XT- 1-molecule is involved in regulation of cell adhesion, an event which must occur in normal development.

cAMP-stimulated rise of [Ca2+]i in rabbit connecting tubules: role of peritubular Ca

1990 ◽  
Vol 258 (3) ◽  
pp. F751-F755 ◽  
Author(s):  
J. E. Bourdeau ◽  
B. K. Eby
Keyword(s):  
Parathyroid Hormone ◽  
Ethylene Glycol ◽  
Cell Activation ◽  
Proximal Tubules ◽  
Tetraacetic Acid ◽  
Luminal Membrane ◽  
Dose Dependent Fashion ◽  
Dose Dependent

Parathyroid hormone (PTH) increases cytosolic free Ca concentration ([ Ca2+]i) by mechanisms that depend on extracellular Ca in both cultured renal proximal tubules and isolated rabbit connecting tubules (CNTs). In CNTs 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) mimics this action, implicating cAMP as a second messenger, and part of the rise, due to increased luminal membrane Ca entry, is likely related to Ca absorption. In cultured proximal tubules the rise in [Ca2+]i, presumably mediated by increased Ca entry across the basolateral plasmalemma, activates gluconeogenesis and shortens microvilli. In the present study we examined cAMP-mediated Ca entry across the basolateral membranes of CNT cells, an effect potentially related to cell activation. Single CNTs were dissected from rabbit kidneys and loaded with fura-2. [Ca2+]i was measured by dual-wavelength excitation during perfusion of isolated segments in vitro. With 1.8 or 2.0 mM Ca in the lumen and the bath, suffusate 8-BrcAMP increased [Ca2+]i within minutes in a dose-dependent fashion. The increase persisted as long as 8-BrcAMP was present and reversed on its withdrawal. With 0.1 microM Ca in the lumen and the bath, 8-BrcAMP, but not ionomycin, failed to increase [Ca2+]i, implying that extracellular Ca is the major source. In tubules perfused with 2 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid to eliminate luminal Ca, but suffused with 1.8 or 2.0 mM Ca, 8-BrcAMP increased [Ca2+]i (though less so than with Ca in the lumen), implying Ca entry across basolateral cell membranes. This rise in [Ca2+]i was attenuated markedly by the presence of 50 microM LaCl3 in the bath.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for a potential role of glucagon during eye growth regulation in chicks

2002 ◽  
Vol 19 (6) ◽  
pp. 755-766 ◽  
Author(s):  
MARITA P. FELDKAEMPER ◽  
FRANK SCHAEFFEL
Keyword(s):  
Visual Processing ◽  
Growth Regulation ◽  
Amacrine Cells ◽  
Early Gene ◽  
Eye Growth ◽  
Dose Dependent Fashion ◽  
High Concentrations ◽  
Dose Dependent ◽  
Glucagon Antagonist

Eye growth and refraction are regulated by visual processing in the retina. Until now, the messengers released by the retina to induce these changes are largely unknown. Previously, it was found that glucagon amacrine cells respond to defocus in the retinal image and even to its sign. The expression of the immediate-early gene product ZENK increased in this cell population in eyes wearing plus lenses and decreased in minus lens-treated chicks. Moreover, it was shown that the amount of retinal glucagon mRNA increased during treatment with positive lenses. Therefore, it seems likely that these cells contribute to the visual regulation of ocular growth and that glucagon may act as a stop signal for eye growth. The purpose of the present study was to accumulate further evidence for a role of glucagon in the visual control of eye growth. Chicks were treated with plus and minus lenses after injection of different amounts of the glucagon antagonist des-His1-Glu9-glucagon-amide or the agonist Lys17,18,Glu21-glucagon, respectively. Refractive development and eye growth were recorded by automated infrared photorefraction and A-scan ultrasound, respectively. The glucagon antagonist inhibited hyperopia development, albeit only in a narrow concentration range, and at most by 50%, but not myopia development. In contrast, the agonist inhibited myopia development in a dose-dependent fashion. At high concentrations, it also prevented hyperopia development.

Chorioamnionitis reduces placental endocrine functions: the role of bacterial lipopolysaccharide and superoxide anion

1997 ◽  
Vol 155 (3) ◽  
pp. 401-410 ◽  
Author(s):  
T Okada ◽  
N Matsuzaki ◽  
K Sawai ◽  
T Nobunaga ◽  
K Shimoya ◽  
...  
Keyword(s):  
Manganese Superoxide Dismutase ◽  
Northern Blot Analysis ◽  
Inflammatory Responses ◽  
Placental Lactogen ◽  
Manganese Superoxide ◽  
Histologic Chorioamnionitis ◽  
Dose Dependent Fashion ◽  
Dose Dependent ◽  
Stimulation Of

Chorioamnionitis has been shown to be one of the most important factors in inducing preterm delivery. The present study was undertaken to examine the effects of chorioamnionitis on placental endocrine functions. Preterm placentas with histologic chorioamnionitis produced smaller amounts of human chorionic gonadotropin (hCG) and human placental lactogen (hPL) than those without chorioamnionitis (P < 0.001). To examine the mechanism involved in the suppression of placental endocrine functions induced by chorioamnionitis, we initially confirmed the expression of lipopolysaccharide (LPS) receptor, i.e. the CD14 molecule, on trophoblasts by Northern blot analysis and immunohistochemistry. We then stimulated purified trophoblasts with LPS, which is the major agent which induces inflammatory responses in the host via the LPS receptor. The trophoblasts stimulated with LPS produced reduced amounts of hCG, hPL, and progesterone in a time- and dose-dependent fashion in spite of the induced manganese-superoxide dismutase (SOD) synthesis. Stimulation of trophoblasts with hypoxanthine and xanthine oxidase resulted in suppressed hCG production, while the simultaneous addition of SOD into the culture medium reversed the suppression of hCG production. LPS in the placenta with chorioamnionitis might directly stimulate trophoblasts through the LPS receptor (CD14), thus reducing placental endocrine functions. Superoxide anions which exogenously act on trophoblasts might be generated by simultaneous stimulation of neutrophils and monocytes at the feto-maternal interface by LPS, and additively reduce placental endocrine functions.

scholarly journals Identification of a new metalloproteinase inhibitor that forms tight-binding complexes with collagenase

1990 ◽  
Vol 269 (1) ◽  
pp. 183-187 ◽  
Author(s):  
T E Cawston ◽  
V A Curry ◽  
I M Clark ◽  
B L Hazleman
Keyword(s):  
Connective Tissue ◽  
Culture Media ◽  
Tight Binding ◽  
Gel Filtration ◽  
Tissue Inhibitor Of Metalloproteinases ◽  
Metalloproteinase Inhibitor ◽  
Dose Dependent Fashion ◽  
Dose Dependent ◽  
Extracellular Activity

Connective-tissue cells produce a family of metalloproteinases which, once activated, can degrade all the components of the extracellular matrix. These potent enzymes are all inhibited by the tissue inhibitor of metalloproteinases (TIMP), and it was thought that the levels of this inhibitor controlled the extracellular activity of these enzymes. We recently detected a new metalloproteinase inhibitor present in culture media of WI-38 fibroblasts. The inhibitor, named ‘large inhibitor of metalloproteinases’ (LIMP), can be separated from TIMP by gel filtration on Ultrogel AcA 44, where it is eluted with an apparent Mr of 76,000. A portion of this inhibitor-containing peak binds to concanavalin A-Sepharose, indicating that at least some of the inhibitor contains carbohydrate. LIMP inhibits collagenase (MMP-1), stromelysin (MMP-3) and gelatinase (MMP-2) in a dose-dependent fashion. Collagenase forms tight-binding complexes with LIMP, which can be separated from free collagenase on gel-filtration columns. The complex is eluted with Mr 81,600 (AcA 44) or Mr 60,000 (Superose 12). This complex is larger than that formed between collagenase and TIMP, which has Mr 52,800 (Aca 44) or 41,000 (Superose 12). Polyclonal antibody to TIMP does not recognize LIMP by immunoblotting, and will not block the inhibition of collagenase by LIMP, showing that LIMP is not a multimeric form of TIMP. The role of this new inhibitor in connective-tissue breakdown studies and its relationship to previously described inhibitors of metalloproteinases is discussed.

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