UMLS:C0043167 - FACTA Search

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Query: UMLS:C0043167 (pertussis)
19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

N-Formyl-methionyl-leucyl-phenylalanine (fMLP) is able to accelerate Ca2+ entry into differentiated HL60 cells by a rather indirect mechanism consisting of the opening of a plasma membrane pathway activated by the emptying of the intracellular Ca2+ stores caused by the agonist. This Ca2+ pathway can also be fully activated by Ca2+ store depletion with thapsigargin. We show here that, in addition to this store-operated Ca2+ entry pathway (SOCP), fMLP is able to activate another receptor-operated Ca2+ pathway in thapsigargin-treated HL60 cells differentiated for 24 h with dimethyl sulfoxide. Activation by fMLP was produced even in cells with fully empty Ca2+ stores. It started 30 s after fMLP addition, was maximal after 2 min and then disappeared within 5 min. This pathway was similar to SOCP in that it allowed passage of Mn2+ and Ba2+ and was antagonized by Ni2+ and by cytochrome P-450 inhibitors. fMLP is also able to inhibit SOCP by a mechanism involving protein phosphorylation. Both the fMLP-induced activation of Ca2+ entry and the inhibition of SOCP were prevented by pretreatment with pertussis toxin. However, the first appeared earlier than the last along differentiation of HL60 cells. This suggests that the inhibition of SOCP requires not only the development of fMLP receptors but also an additional component placed distally to the G protein in the transduction mechanism.
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PMID:Activation by chemotactic peptide of a receptor-operated Ca2+ entry pathway in differentiated HL60 cells. 796 26

The role of heterotrimeric GTP-binding proteins in the process of store-operated Ca2+ inflow in hepatocytes was investigated by testing the ability of pertussis toxin to inhibit thapsigargin- and 2,5-di-tert-butylhydroquinone (DBHQ)-induced bivalent cation inflow. Hepatocytes isolated from rats treated with pertussis toxin for 24 h exhibited markedly inhibited rates of both Ca2+ and Mn2+ inflow when these were stimulated by vasopressin, angiotension II, epidermal growth factor, thapsigargin and DBHQ. Pertussis toxin had little effect on the basal intracellular free Ca2+ concentration ([Ca2+]i), basal rates of Ca2+ and Mn2+ inflow, the abilities of vasopressin, angiotensin II, thapsigargin and DBHQ to induce the release of Ca2+ from intracellular stores, and the maximum value of [Ca2+]i reached following agonist-induced release of Ca2+ from intracellular stores. It is concluded that store-operated Ca2+ inflow in hepatocytes employs a slowly ADP-ribosylated trimeric GTP-binding protein and is the physiological mechanism, or one of the physiological mechanisms, by which vasopressin and angiotensin stimulate plasma membrane Ca2+ inflow in this cell type.
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PMID:Evidence from studies with hepatocyte suspensions that store-operated Ca2+ inflow requires a pertussis toxin-sensitive trimeric G-protein. 798 Mar 92

Stimulation of neuropeptide Y (NPY) Y2 receptors induced an intracellular free Ca2+ ([Ca2+]i) increase in a human neuroblastoma cell line, CHP-234. When NPY in a Ca(2+)-free solution was applied, this increase was abolished. Depolarization with high KCl evoked no response, suggesting that the responses were not mediated by voltage-gated Ca2+ channels. There was no evidence that the NPY response consisted of a capacitative Ca2+ entry sensitive to internal Ca2+ store levels. The [Ca2+]i elevation was diminished by Ni2+, a blocker of Ca2+ entry. Mn2+ induced a quench of the fura-2 fluorescence, which ceased promptly upon the removal of NPY, indicating that Ca2+ entry was linked tightly to receptor activation. Although thapsigargin- and ryanodine-sensitive Ca2+ stores were present, NPY-induced responses were not impaired by pretreatment with either drug. Furthermore, NPY had no effect on the thapsigargin-sensitive store. Pertussis toxin did not affect the NPY-stimulated [Ca2+]i increase, although it abolished the NPY-dependent inhibition of cAMP production. It is concluded that the Y2 receptors couple directly to receptor-operated Ca2+ channels without the involvement of intracellular Ca2+ stores. The results also indicate that Y2 receptors can activate both pertussis toxin-sensitive and -insensitive mechanisms in the same cell.
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PMID:A pertussis toxin-insensitive calcium influx mediated by neuropeptide Y2 receptors in a human neuroblastoma cell line. 813 47

To study the cellular basis for FSH-stimulated dose-dependent graded increases in intracellular Ca2+ concentrations in populations of Sertoli cells, we investigated the effects of FSH on free Ca2+ ion concentrations ([Ca2+]i) in individual rat Sertoli cells using the Ca(2+)-sensitive dye fura-2/AM and digital fluorescent videomicroscopy. Ovine or rat FSH elicited a hormone-specific rise in [Ca2+]i within 20-140 sec, with a peak level 2.7 +/- 0.9-fold greater than the basal value (mean +/- SEM; n = 8) lasting for 4-16 min. The amplitude and kinetics of the FSH-induced [Ca2+]i signal were not dose dependent. Instead, increasing doses of FSH recruited a higher percentage of responding cells. Chelation of extracellular Ca2+ or cotreatment with verapamil or cobalt abolished FSH-induced [Ca2+]i increases. Furthermore, in the presence of extracellular Mn2+, direct evidence for FSH-mediated Ca2+ influx was obtained from the quench of fura-2 fluorescence. Induced Ca2+ increases were mimicked by forskolin or protein kinase-A type I activators [8-(6-amino-hexyl)amino-cAMP and N6-benzoyl-cAMP (N6B)]. However, the cAMP analogs, 8-bromo-cAMP, N6,2'-O-dibutyryl cAMP, or protein kinase-A type II activators (8-thiomethyl-cAMP and N6B), induced [Ca2+]i increases even in the absence of extracellular Ca2+, and the time course of the [Ca2+]i rise induced by cAMP analogs was more rapid than that induced by FSH. Similarly, the uninhibited rise in [Ca2+]i induced by FSH in pertussis toxin-pretreated Sertoli cells suggests that PT-sensitive G-proteins are not involved in the action of FSH on [Ca2+]i. In summary, we demonstrate that FSH evokes sustained [Ca2+]i increases in single Sertoli cells in a nongraded fashion and recruits increasing numbers of responding cells in a dose-dependent fashion. We also provide explicit evidence that FSH induces Ca2+ influx. Mimicry of the FSH-induced [Ca2+]i rise by certain cAMP analogs [8-(6-amino-hexyl)amino-cAMP and N6B; protein kinase-A type I activator] or forskolin suggests that Ca2+ may be part of a dual pathway of cAMP-initiated intracellular signaling.
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PMID:Cellular basis for follicle-stimulating hormone-stimulated calcium signaling in single rat Sertoli cells: possible dissociation from effects of adenosine 3',5'-monophosphate. 813 59

The Bordetella pertussis gene sodB, encoding superoxide dismutase (SOD), was cloned by complementation of an Escherichia coli sodAsodB double mutant. The nucleotide sequence of sodB predicted a 21-kDa protein with homology to manganese- and iron-containing SODs from other organisms. Examination of SOD activity on gels suggests that B. pertussis extracts have a single SOD containing Fe3+ as a prosthetic group. A SOD-deficient mutant was obtained by insertional inactivation of sodB in B. pertussis, confirming that there is only one SOD in this organism.
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PMID:Characterization of the gene encoding superoxide dismutase of Bordetella pertussis and construction of a SOD-deficient mutant. 818 62

The 5-hydroxytryptamine1A receptor (5-HT1AR) is a G-protein-coupled receptor negatively coupled to adenylyl cyclase (AC). We have studied the functional domains of 5-HT1AR using synthetic peptides to block or mimic receptor function. The entire second intracellular loop (5-HT1AR-i2) and the carboxyl end of the third intracellular loop (5-HT1AR-i3-C) strongly inhibited forskolin-stimulated AC activity. These effects were not additive with those of 5-HT. Like 5-HT, the peptides 5-HT1AR-i3-C and -i2 weakly inhibited AIF4- and Mn2+ stimulated AC activity. 5-HT1AR binding assays indicated that peptides could interact with the same G-protein pool as the 5-HT1AR. 5-HT1AR-i3-C- and -i2-stimulated [35S]guanosine 5'-O-(thiotriphosphate) binding on Go/Gi proteins. Only 5-HT1AR-i3-C partially adopted an alpha-helical conformation in solution. These data show that different domains in the 5-HT1AR second and third intracellular loops can couple to and activate Gi proteins in order to mediate AC inhibition. Peptide-induced AC inhibition was not sensitive to pertussis toxin as opposed to the 5-HT1AR-mediated effect. Our data show that the 5-HT1AR and the 5-HT1AR peptides activate Gi proteins in a slightly different manner.
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PMID:5-Hydroxytryptamine1A receptor synthetic peptides. Mechanisms of adenylyl cyclase inhibition. 820 93

The mechanism by which complement fragment C5a elevates intracellular Ca2+ ([Ca2+]i) levels in two cell types, a monocytic cell line, U937, and neutrophils, has been investigated by the use of fluorometric and radiometric techniques. In U937 cells the influx of extracellular Ca2+ can be distinguished from the release of intracellular Ca2+ stores in terms of dose-responsiveness to C5a and sensitivity to pertussis-toxin poisoning. This suggests that the mechanism of Ca2+ influx in these cells is at least partially independent of both the production of inositol phosphates and elevation of internal Ca2+ concentration. The C5a-stimulated influx of 45Ca2+ into U937 cells is inhibited by a series of metal ions (Zn2+ > Co2+ > Mn2+ > Sr2+ approximately equal to Ni2+ > La3+). The stimulated influx of Ca2+ into neutrophils is inhibited differently (Ni2 >> Co2+ > Zn2+ approximately equal to La3+ > Mn2+ approximately equal to Sr2+), is less sensitive to C5a and both the influx of extracellular Ca2+ and the release of intracellular stores are equally sensitive to pertussis toxin treatment. Taken together these results indicate that [Ca2+]i is controlled in U937 monocytes by mechanisms distinct from those which appear to operate in other myeloid cells, such as neutrophils, stimulated with C5a and formylpeptide.
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PMID:Characterization of a complement-fragment-C5a-stimulated calcium-influx mechanism in U937 monocytic cells. 824 Feb 77

The activity of a hormone- and growth-factor-stimulated NADH oxidase of the rat liver plasma membrane responds to guanine nucleotides, but in a manner that differs from that of the classic trimeric and low-molecular-mass monomeric G-proteins. In the absence of added bivalent ions, both GTP and GDP as well as guanosine 5'-[gamma-thio]triphosphate (GTP[gamma-S]) but not guanosine 5'[beta-thio]diphosphate (GDP[beta-S]) stimulate the activity over the range 1 microM to 100 microM. Other di- and tri-nucleotides also stimulate, but only at concentrations of 100 microM or higher. Added bivalent ions are not required either for NADH oxidation or guanine nucleotide stimulation. Bivalent ions (Mg2+ > Mn2+ > or = Ca2+) alone stimulate only slightly at low concentrations and then inhibit at high concentrations. The inhibitions are augmented by GDP or GTP [gamma-S] but not by GTP. Although the activity is the same, or less, in the presence of 0.5 mM MgCl2, GTP at 1-100 nM and other nucleotides at 0.1 mM or 1 mM still stimulate in its presence. The NADH oxidase is activated by mastoparan but aluminum fluoride is weakly inhibitory. Cholera and pertussis toxins elicit only marginal responses. Both the Mg2+ and the GDP and GTP[gamma-S] inhibitions (but not the GTP stimulations) shift to higher concentrations when the membrane preparations are first solubilized with Triton X-100. The results suggest a role for guanine nucleotides in the regulation of plasma membrane NADH oxidase, but with properties that differ from those of either trimeric or the low-molecular-mass G proteins thus far described.
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PMID:NADH oxidase activity of rat liver plasma membrane activated by guanine nucleotides. 831 95

The effect of sphingosine on the cytosolic free Ca2+ concentrations, [Ca2+]i, of human neutrophils was re-examined using Fura-2 loaded cells. We found that sphingosine induced a dose-dependent elevation of [Ca2+]i. At sphingosine concentrations > or = 10 microM, the rise in [Ca2+]i was biphasic; an initial phase increasing basal [Ca2+]i by 100% was succeeded by a second phase which raised [Ca2+]i to several microM. The enhanced signal was sustained and slowly approached the Fmax of Fura-2 over 10 min. Although cytotoxicity assays indicate that Fura-2 leakage contributed to the rise in fluorescence, EGTA, surprisingly, had no effect on the time course of this response. The explanation was that EGTA blocked Fura-2 leakage from and trypan blue uptake by neutrophils. Thus, in the presence of EGTA, biphasic increases in the fluorescent signal can be attributed mainly to release of intracellular Ca2+. Mn2+ quenching studies confirmed that sphingosine mobilized Ca2+ in two distinct phases and promoted the influx of Mn2+. Mn2+ entry, however, was not matched by substantial Ca2+ influx. Sphingosine elevation of [Ca2+]i was insensitive to pertussis toxin treatment of neutrophils and was not correlated with (1,4,5)IP3 formation. Studies with semi-permeabilized cells show that sphingosine, up to 80 microM, neither mobilized Ca2+ significantly nor inhibited active Ca2+ sequestration. Sphingosylphosphorylcholine induced a small but dose-dependent release of Ca2+. We hypothesize that a metabolite of sphingosine may release Ca2+ directly in intact neutrophils.
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PMID:Sphingosine mobilizes intracellular calcium in human neutrophils. 835 72

The non-hydrolysable GTP analogue guanylyl 5'-imidodiphosphate (p[NH]ppG) elicited a profound increase in the adenylate cyclase activity of human platelets. This occurred after a well-defined lag period of around 6 min, whereupon an enhanced steady-state rate was evident. The duration of the lag period was unchanged over a range of concentrations of p[NH]ppG which gave very different steady-state rates of adenylate cyclase activity. Prior activation of the stimulatory G-protein Gs by cholera-toxin pre-treatment abolished the lag period and elicited a small increase in the steady-state rate. Manipulating function of the inhibitory G-protein Gi also led to profound changes in the lag periods. Thus marked decreases in the lag were seen (approximately 70-81%) when Gi function was ablated through pre-treatment of platelet membranes with pertussis toxin, or by using elevated (25 mM) Mg2+ levels in the assay, or when Mg2+ was replaced by 5 mM Mn2+ in the assay. In contrast with this, potentiation of Gi function led to an increase in the lag period, as seen under conditions of agonist occupancy of inhibitory alpha 2-adrenoceptors (increase approximately 74%) or with the addition of 100 mM NaCl to the assays (increase approximately 44%). The local anaesthetic and membrane-fluidizing agent benzyl alcohol elicited both a profound decrease (around 70% at 80 mM) in the p[NH]ppG-induced lag period and a marked augmentation (around 5-fold) in the steady-state adenylate cyclase activity. When adenylate cyclase assays were done at 35 degrees C instead of 25 degrees C, then the lag period for activation by p[NH]ppG was decreased by around 33% and the steady-state rate increased by around 3-fold. At 35 degrees C, the addition of benzyl alcohol led to the apparent abolition of the lag period for p[NH]ppG activation of adenylate cyclase and amplified the steady-state rate by only around 2.2-fold. It is shown that Gi plays a fundamental role in determining the rate of activation of Gs. The proposal is formulated that such an action may be mediated through the release of beta gamma-subunits. Thus beta gamma-subunit dissociation is proposed as providing the rate-limiting step in Gi activation.
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PMID:The role of Gi and the membrane-fluidizing agent benzyl alcohol in modulating the hysteretic activation of human platelet adenylate cyclase by guanylyl 5'-imidodiphosphate. 848 20

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