Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tumor metastasis requires highly motile cells that can respond to appropriate stimuli. A2058 human melanoma cells were shown previously to secrete a highly potent autocrine motility factor (AMF) that stimulates chemokinetic movement. We have shown that the insulin polypeptides (IPs; insulin-like growth factors I and II [IGF-I, -II] and insulin) stimulated A2058 cell chemotaxis and chemokinesis. We now report that the IPs and AMF stimulate locomotion in other human malignant cell lines. Insulin (100 nM) induced motility of up to 50% of the magnitude of the AMF response in human carcinoma lines MDA-231 (breast), T24 (bladder), and OVCAR3 (ovarian). The tumorigenic and metastatic 5R Haras-transfected rat embryo fibroblast cell line responded to insulin with both chemotaxis and chemokinesis and was 100% of that seen for AMF. The ED50 for IGF-I in the carcinoma cell lines was in the order of I nM, but the magnitude of the responses at this concentration was 40% of the AMF-stimulated response, with the exception of the A2058 cells, which were maximally stimulated at I nM. IGF-II induced maximal motility of 75 to 130% of the AMF-stimulated response in the carcinoma lines with ED50 of less than or equal to 10 nM. IGF-II-stimulated motility in the carcinoma lines was predominantly chemotactic by modified checkerboard analysis. Cell pretreatment with pertussis toxin inhibited 90-100% of AMF-induced motility, whereas migration to the IPs was not pertussis toxinsusceptible. In growth studies, IGF-I induced mitogenesis up to 140% of basal media control growth. In general, maximal growth stimulation was seen at 100 nM IGF-I, and optimal migration was seen at 10 nM IGF-I. The IGFs are secreted by normal stroma in a number of organs that are common sites for primary and metastatic disease. Therefore, we suggest that IPs may be important homing and mitogenic signals for tumor cells in the process of invasion and metastasis and that the differential motility stimulation and respective mechanisms of action by these physiologically important agents may underlie the diversity of the metastatic process.
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PMID:Heterogeneity of the motility responses in malignant tumor cells: a biological basis for the diversity and homing of metastatic cells. 211 98

In this study, we examined the effects of pertussis toxin (PT) on the ADP-ribosylation of guanine nucleotide binding proteins (G-proteins) and various insulin-stimulated processes in cultured BC3H-1 myocytes. Treatment of intact myocytes with 0.1 microgram/ml PT for 24 hours resulted in the complete ribosylation of a 41 kDa protein. The 41 kDa PT substrate was immunoprecipitated with antibodies directed against a synthetic peptide corresponding to a unique sequence in the alpha subunit of Gi-proteins. PT treatment of intact cells had no effect on insulin receptor binding or internalization. However, PT inhibited insulin-stimulated glucose transport at all insulin-concentrations tested (1-100 ng/ml). Maximally stimulated glucose transport was reduced by 50% +/- 15%. Insulin-stimulated glucose oxidation was also decreased by 31% +/- 8%. The toxin had no significant effect on the basal rates of glucose transport and glucose oxidation. The time course of PT-induced inhibition on glucose transport correlated with the time course of the "in vivo" ADP-ribosylation of the 41 kDa protein. The results suggest that a 41 kDa PT-sensitive G-protein, identical or very similar to Gi, is involved in the regulation of glucose metabolism by insulin in BC3H-1 cells.
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PMID:Pertussis toxin catalyzed ADP-ribosylation of a 41 kDa G-protein impairs insulin-stimulated glucose metabolism in BC3H-1 myocytes. 211 47

We studied the mechanism whereby insulin activates de novo phosphatidic acid synthesis in BC3H-1 myocytes. Insulin rapidly activated glycerol-3-phosphate acyltransferase (G3PAT) in intact and cell-free preparations of myocytes in a dose-related manner. The apparent Km of the enzyme was decreased by treatment with insulin, whereas the Vmax was unaffected. No activation was found by ACTH, insulin-like growth factor-I, angiotensin II, or phenylephrine, but epidermal growth factor, which, like insulin, is known to activate de novo phosphatidic acid synthesis in intact myocytes, also stimulated G3PAT activity. In homogenates or membrane fractions, the effect of insulin on G3PAT was fully mimicked by nonspecific or phosphatidylinositol (PI)-specific phospholipase C (PLC). An antiserum raised against PI-glycan-PLC completely blocked the effect of insulin on G3PAT. Although the above findings suggested involvement of a PLC in insulin-induced activation of G3PAT, neither diacylglycerol nor protein kinase C activation appeared to be involved. On the other hand, insulin stimulated the release of a cytosolic factor, which activated membrane-associated G3PAT. This cytosolic factor had a molecular weight of less than 5K as determined by Sephadex G-25 chromatography. NaF, a phosphatase inhibitor, blocked the activation of G3PAT by insulin, suggesting involvement of a phosphatase. Insulin-induced activation of G3PAT was also blocked by pretreatment of intact myocytes with pertussis toxin and by prior addition, to homogenates, of an antiserum that recognizes the C-terminal decapeptide of Gi alpha.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Insulin activates glycerol-3-phosphate acyltransferase (de novo phosphatidic acid synthesis) through a phospholipid-derived mediator. Apparent involvement of Gi alpha and activation of a phospholipase C. 217 32

Addition of vasopressin (100 nM) to rat hepatocytes prelabelled with [3H]inositol stimulated the production of inositol phosphates in the presence of 20 mM Li+. Preincubation of hepatocytes with insulin (50 nM) or glucagon (10 nM) had no significant effect alone but enhanced the effects of vasopressin after a lag period of at least 1 min. The effects of insulin and glucagon appeared additive in this respect. Insulin also enhanced the norepinephrine-mediated stimulation of inositol phosphate accumulation. The enhancement by insulin of the effects of vasopressin required at least 0.5-5 nM insulin and did not involve changes in [3H]inositol lipid labelling or IP3 phosphatase activity. The effect of insulin appeared insensitive to prior treatment of hepatocytes with pertussis toxin (200 ng/ml for 18-24 h) or cholera toxin (100 ng/ml for 3-4 h). The glucagon enhancement of the effects of vasopressin was not affected by pertussis toxin but was mimicked by cholera toxin. The response of hepatocytes to vasopressin in the absence of Li+ was smaller and more transient. Under these conditions a 5 min prior incubation with insulin inhibited the stimulation by vasopressin of inositol phosphate accumulation. A similar inhibitory effect of prior insulin exposure on the transient activation by vasopressin of exogenous phosphatidylinositol 4,5-bisphosphate breakdown by hepatocyte homogenates was also seen. These data indicate that insulin, although having no effect on basal inositol phosphate accumulation, can either enhance or antagonise the effects of vasopressin in primary rat liver hepatocyte cultures depending on the experimental conditions.
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PMID:Effects of insulin on inositol phosphate production in cultured rat hepatocytes. 218 Apr 88

Elevation of cyclic AMP (cAMP) content in perfused rat hearts by exposure to glucagon, forskolin, and 1-methyl-3-isobutylxanthine (IBMX) increased rates of protein synthesis during the second hour of perfusion with buffer that contained glucose in the absence of added insulin. When tetrodotoxin was added to arrest contractile activity, glucagon, forskolin, and IBMX still elevated cAMP content and rates of protein synthesis. Perfusion of beating rat hearts at elevated aortic pressure (120 mm Hg vs. 60 mm Hg) also accelerated rates of protein synthesis and raised cAMP content and cAMP-dependent protein kinase activity during the second hour of perfusion. Insulin accelerated rates of protein synthesis in beating hearts during the first and second hour of perfusion but did not increase cAMP content. Elevation of aortic pressure in insulin-treated hearts raised cAMP content but had no further effect on rates of protein synthesis. Perfusion of arrested hearts for as little as 2 minutes at 120 mm Hg resulted in a rapid and sustained increase in cAMP content, cAMP-dependent protein kinase activity, and rate of protein synthesis after 60-120 minutes of additional perfusion at 60 mm Hg. Exposure of arrested hearts to 0.2 mM methacholine, a muscarinic-cholinergic agonist, for 5 minutes before elevation of perfusion pressure blocked the pressure-induced increases in cAMP content, cAMP-dependent protein kinase activity, and rates of protein synthesis. When hearts were removed from pertussis toxin-treated animals, methacholine did not block the effects of forskolin on these same three parameters. These studies indicated that elevation of tissue cAMP by hormone binding, direct activation of adenylate cyclase, or inhibition of phosphodiesterase resulted in acceleration of protein synthesis. Furthermore, the effects of increased aortic pressure to accelerate synthesis appeared to involve a cAMP-dependent mechanism that was independent of changes in contractile activity but could be blocked with a muscarinic-cholinergic agonist. Acceleration of protein synthesis by insulin was not associated with an elevation of cAMP.
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PMID:Increased cyclic AMP content accelerates protein synthesis in rat heart. 247 73

Insulin inhibited the ability of activated pertussis toxin to catalyse the ADP-ribosylation of alpha-Gi in isolated plasma membranes in either the absence of added guanine nucleotides or in the presence of GTP. In contrast, when the non-hydrolysable GTP analogue guanylyl-5'-imido-diphosphate (p[NH]ppG) was added to ribosylation mixtures, to inhibit the action of pertussis toxin in catalysing the ADP-ribosylation of alpha-Gi, then the addition of insulin attenuated the action of p[NH]ppG causing an increase in alpha-Gi ribosylation. Pre treatment of intact hepatocytes with insulin had no effect on the subsequent ability of thiol-preactivated pertussis toxin to cause the ADP-ribosylation of alpha Gi using isolated membranes from such cells. The ability of p[NH]ppG to inhibit forskolin-stimulated adenylate cyclase activity was attenuated in the presence of insulin. Insulin did not cause the phosphorylation of alpha-Gi in either intact hepatocytes or in isolated membranes.
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PMID:Insulin affects the ability of Gi to be ADP-ribosylated but does not elicit its phosphorylation in intact hepatocytes. 251 46

Antilipolysis induced by insulin by adenylate cyclase inhibitors was compared in isolated human fat cells when lipolysis was activated at well-defined steps in the cyclic AMP system. The latter was achieved with isoprenaline (beta-adrenoreceptor agonist), cholera toxin and pertussis toxin (acting on the GTP-sensitive coupling proteins), forskolin (stimulating the catalytic component of adenylate cyclase), enprofylline (selective phosphodiesterase inhibitor) and N6-monobutyryl-cyclic-AMP or 8-bromo cyclic-AMP (cyclic AMP analogues which are resistant or sensitive to phosphodiesterase, respectively). Clonidine (alpha 2-adrenoreceptor agonist), prostaglandin E2 and N6-(phenylisopropyl) adenosine (adenosine analogue) failed to inhibit lipolysis stimulated by cholera toxin or pertussis toxin, but were effective under all other conditions. Insulin failed to inhibit lipolysis stimulated by enprofylline or N6-monobutyryl cyclic AMP, but was effective under all other circumstances. In conclusion, insulin and adenylate cyclase inhibitors are antilipolytic in human fat cells through different mechanisms. Adenylate cyclase inhibitors act predominantly on the GTP-sensitive coupling proteins and, to a minor extent, at some yet unidentified distal step in the lipolytic machinery. As regards insulin, the major site of the antilipolytic action is phosphodiesterase.
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PMID:Antilipolytic effects of insulin and adenylate cyclase inhibitors on isolated human fat cells. 254 39

Insulin-like growth factors I and II (IGF-I and II) and insulin are chemotactic agents for the human melanoma cell line A2058. As shown in this report, the motility receptor mediating this response is the heterodimeric type I IGF receptor. These three factors are able to compete with 125I-labeled IGF-I for binding to the cell surface with IC50 values equal to approximately 2 (IGF-I), approximately 150 (IGF-II), and approximately 300 nM (insulin). Cross-linking of 125I-IGF-I to the cell surface with disuccinimidyl suberate followed by analysis with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography reveals a 130-kDa protein (reduced) consistent with the alpha component of a type I receptor and a 38-kDa protein which does not bind insulin, and thus could be another IGF-I cell surface binding protein. The anti-IGF-I receptor monoclonal antibody (alpha IR-3) also competes with labeled IGF-I in binding experiments. In contrast, a control monoclonal antibody, matched to alpha IR-3 with respect to IgG subclass, has no significant effect on IGF-I binding. While alpha IR-3 inhibits the motility induced by IGF-I, IGF-II, and insulin, pertussis toxin (0.01-1.0 micrograms/ml) has no significant effect on the motility induced by the insulin-like growth factors or insulin on this cell line. Therefore, the type I IGF receptor appears to mediate a highly potent pertussis toxin-insensitive motility response to IGF-I, IGF-II, and insulin. In contrast, motility induced by the autocrine motility factor, a cytokine produced by the A2058 cells, is not affected by alpha IR-3 but is extremely sensitive to pertussis toxin. When mixtures of autocrine motility factor and IGF-I are employed to induce chemotaxis, the resulting motility is greater than that induced by either agent alone. These data indicate that motility in this melanoma cell line can be initiated through multiple receptors that stimulate the cells by separate transduction pathways. This capability to respond to multiple stimuli could enhance the metastatic potential.
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PMID:The type I insulin-like growth factor receptor is a motility receptor in human melanoma cells. 255 32

The potential role of guanine nucleotide regulatory proteins (G-proteins) in acute insulin regulation of glucose transport was investigated by using bacterial toxins which are known to modify these proteins. Cholera-toxin treatment of isolated rat adipocytes had no effect on either 2-deoxyglucose transport or insulin binding. Pertussis-toxin treatment resulted in an inhibition of both insulin binding and glucose transport. Insulin binding was decreased in pertussis-toxin-treated cells by up to 40%, owing to a lowering of the affinity of the receptor for hormone, with no change in hormone internalization. The dose-response curve for insulin stimulation of glucose transport was strongly shifted to the right by pertussis-toxin treatment [EC50 (half-maximally effective insulin concn.) = 0.31 +/- 0.04 ng/ml in control cells; 2.29 +/- 1.0 in treated cells), whereas cholera toxin had only a small effect (EC50 = 0.47 +/- 0.02 ng/ml). Correcting for the change in hormone binding, pertussis toxin was found to decrease the coupling efficiency of occupied receptors (50% of maximal insulin effect with 928 molecules bound/cell in control and 3418 in treated cells). Pertussis-toxin inhibition of insulin sensitivity was slow in onset, requiring 2-3 h for completion. Under conditions where pertussis-toxin inhibition of insulin sensitivity was maximal, a 41,000 Da protein similar to the alpha subunit of Gi (the inhibitory G-protein) was found to be fully ribosylated. These results are consistent with the concept that pertussis-toxin-sensitive G-protein(s) can modify the insulin-receptor/glucose-transport coupling system.
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PMID:Role of guanine nucleotide regulatory proteins in insulin stimulation of glucose transport in rat adipocytes. Influence of bacterial toxins. 255 36

The mechanism by which alpha 2-adrenergic agonists inhibit exocytosis was investigated in electrically permeabilized insulin secreting RINm5F cells. In this preparation alpha 2-adrenoceptors remain coupled to adenylate cyclase, since basal- and forskolin-stimulated cyclic AMP production was lowered by epinephrine and clonidine by 30-50%. Cyclic AMP levels did not correlate with the rate of insulin secretion. Thus, at low Ca2+, forskolin enhanced cyclic AMP levels 5-fold without eliciting secretion, and Ca2+-stimulated secretion was associated with decreased cyclic AMP accumulation. Epinephrine (plus propranolol) inhibited Ca2+-induced insulin secretion in a GTP-dependent manner. The maximal inhibition (43%) occurred at 500 microM GTP. Clonidine also inhibited Ca2+-stimulated secretion. Replacement of GTP by GDP or by the nonhydrolyzable GTP analog guanosine 5'-(3-O-thio)triphosphate as well as treatment of the cells with pertussis toxin prior to permeabilization abolished epinephrine inhibition of insulin secretion. Pertussis toxin did not affect Ca2+-stimulated secretion. Insulin release stimulated by 1,2-didecanoyl glycerol was also lowered by epinephrine suggesting an effect distal to the activation of protein kinase C (Ca2+/phospholipid-dependent enzyme). These results taken together with the ability of epinephrine to inhibit ionomycin-induced insulin secretion in intact cells suggest that alpha 2-adrenergic inhibition is distal to the generation of second messengers. A model is proposed for alpha 2-adrenoceptor coupling to two effector systems, namely the adenylate cyclase and the exocytotic site in insulin-secreting cells.
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PMID:GTP-dependent inhibition of insulin secretion by epinephrine in permeabilized RINm5F cells. Lack of correlation between insulin secretion and cyclic AMP levels. 283 60


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