Mastoparan inhibits phosphoinositide hydrolysis via pertussis toxin‐intensive G‐protein in human astrocytoma cells

Nakahata, Norimichi; Abe, Marilene Tamiko; Matsuoka, Isao; Nakanishi, Hironori

doi:10.1016/0014-5793(90)80074-s

Cited by 51 publications

(35 citation statements)

References 17 publications

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“…6). Incubating the cells for 5 h in 1 µM mastoparan, which can either activate G-protein dependent mechanisms (Higashijima et al 1988) or inhibit some pertussis toxin-insensitive Gprotein activation of phosphoinositide hydrolysis in human astrocytoma cells (Nakahata et al 1990), did not alter or mimic histamine´s action (n=4) (Fig. 6).…”

Section: Resultsmentioning

confidence: 99%

Histamine H1 receptors in C6 glial cells are coupled to calcium-dependent potassium channels via release of calcium from internal stores

Weiger

Stevens

Wunder

et al. 1997

Naunyn-Schmiedeberg's Arch Pharmacol

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We investigated the action of histamine on C6-astroglioma cells using patch clamp recording and intracellular calcium measurement. Application of 100 microM histamine hyperpolarized the resting membrane potential and increased free intracellular calcium. Membrane hyperpolarization was accompanied by a decrease in input resistance. The effect of histamine was reversible and responses persisted following repeated applications. In voltage clamp experiments histamine elicited an outward current associated with a conductance increase and a reversal potential near the Nernst potential for potassium. The action of histamine was blocked by mepyramine but not by cimetidine or thioperamide suggesting that a H1 receptor mediated the response. Quinidine and charybdotoxin, but not apamin, blocked the hyperpolarization. Buffering internal calcium with BAPTA diminished the activation of the potassium channel, suggesting a calcium-dependent K(+)-channel, which was also found to be regulated by protein kinase C and phosphatases. The increase in intracellular calcium was not dependent on external calcium or sensitive to pertussis toxin, cholera toxin, forskolin or 8-bromo-cAMP. Both the hyperpolarization and the increase in intracellular calcium were blocked by thapsigargin or the phospholipase C inhibitor U73122. These results indicate that histamine liberates calcium from internal stores by activation of phospholipase C which in turn leads to an increase of intracellular Ca2+ and thereby to the activation of a calcium-dependent potassium channel in C6 glial cells.

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Section: Resultsmentioning

confidence: 99%

Histamine H1 receptors in C6 glial cells are coupled to calcium-dependent potassium channels via release of calcium from internal stores

Weiger

Stevens

Wunder

et al. 1997

Naunyn-Schmiedeberg's Arch Pharmacol

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“…Because it has been revealed that mastoparan directly activates G i/o in a pertussis toxin-sensitive manner, mastoparan has been assumed to be a G-protein activator (Higashijima et al, 1988). We have demonstrated previously that mastoparan suppressed phosphoinositide hydrolysis induced by the muscarinic receptor agonist carbachol in 1321N1 human astrocytoma cells (Nakahata et al, 1990). Likewise, Wojcikiewicz and Nahorski (1989) showed that mastoparan inhibited phosphoinositide hydrolysis induced by guanosine 5Ј-O-(3-thio)triphosphate in permeabilized SH-SY5Y human neuroblastoma cells.…”

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confidence: 77%

“…3 H]inositol phosphates as described previously (Nakahata et al, 1990). In brief, PC-12 cells were cultured in 12-well plates at the density of 2.0 ϫ 10 5 cells/well.…”

Section: Methodsmentioning

confidence: 99%

Mastoparan Changes the Cellular Localization of Gα_q/11and Gβ through Its Binding to Ganglioside in Lipid Rafts

Sugama

Ohkubo²,

Atsumi³

et al. 2005

Mol Pharmacol

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Although it is known that mastoparan, a wasp venom toxin, directly activates G i/o , mastoparan-induced biological responses are not always explained by this mechanism. For instance, we have demonstrated previously that mastoparan suppressed phosphoinositide hydrolysis induced by carbachol in human astrocytoma cells (FEBS Lett 206:91-94, 1990). In the present study, we examined whether mastoparan affected phosphoinositide hydrolysis by interacting with lipid rafts in PC-12 cells. Mastoparan inhibited UTP-induced increase in [Ca 2ϩ ] i and phosphoinositide hydrolysis in a concentrationdependent manner. UTP-induced phosphoinositide hydrolysis occurred in lipid rafts, because methyl-␤-cyclodextrin, a disrupting regent of lipid rafts, inhibited the hydrolysis. Mastoparan changed the localization of G␣ q/11 and G␤ together with cholesterol from lipid rafts to nonraft fractions or cytosol. These changes were inhibited by ganglioside mixtures, suggesting that mastoparan interacts with gangliosides in lipid rafts. In fact, ganglioside mixtures and neuraminidase, but not sialic acid, attenuated the inhibitory effect of mastoparan on phosphoinositide hydrolysis. Furthermore, fluorescence intensity of tyrosine residue of [Tyr 3 ]mastoparan was potentiated by ganglioside mixtures, suggesting the direct binding of mastoparan to gangliosides. Mastoparan caused cytotoxicity of PC-12 cells in a concentration-dependent manner, determined by LDH release. The mastoparan-induced cytotoxicity was significantly inhibited by neuraminidase or gangliosides. The order of inhibitory potency of gangliosides was GT1b Ϸ GD1b Ͼ GD1a Ͼ GM1 Ͼ Ͼ GQ1b, but asialo-GM1 and sialic acid were inactive. These results suggest that mastoparan initially binds to gangliosides in lipid rafts and then it inhibits phosphoinositide hydrolysis by changing the localization of G␣ q/11 and G␤ in lipid rafts.

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“…18 The ability of mastoparan to penetrate membranes and activate G proteins in intact cells has been demonstrated in mast cells, 12 pulmonary artery endo-thelial cells, 19 and human astrocytoma cells. 20 In phospholipid bilayers, mastoparan exhibits a greater affinity for d and G o than for G,, 9 although the affinity for G q proteins has not been examined. In the current experiment, pertussis toxin treatment at a concentration that ADP ribosylates endogenous G proteins in intact vascular preparations 21 did not affect the contractile response to mastoparan, so the G protein activated in vascular smooth muscle cells does not appear to be G, or G o .…”

Section: Discussionmentioning

confidence: 99%

Enhanced vascular reactivity to mastoparan, a G protein activator, in genetically hypertensive rats.

Kanagy

Webb

1994

Hypertension

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Vascular smooth muscle from stroke-prone spontaneously hypertensive rats has an increased responsiveness to the vasoconstrictors angiotensin II and serotonin. This abnormality is postulated to contribute to the hypertension characteristic of this strain of rats. We hypothesized that a portion of the increased responsiveness may be due to altered function of G proteins. This hypothesis was tested using mastoparan, a peptide that mimics ligand-bound receptors to stimulate G proteins directly. In addition, we investigated the mechanism of mastoparan-induced contraction of vascular smooth muscle. Changes in isometric tension were recorded in denuded carotid artery strips from hypertensive and normotensive (Wistar-Kyoto) rats. Vascular strips from the hypertensive rats had a significantly greater response to mastoparan at all concentrations between 10~8 and 10" 5 mol/L. A G protein inhibitor, A^-ethylmaleimide (10~3 mol/L), attenuated the response to mastoparan (10~7 mol/L) (67±4% of control re-H ypertension is associated with altered vascular reactivity to many agonists. The inbred strain of stroke-prone spontaneously hypertensive rats (SHRSP) specifically exhibits increased sensitivity to vasoconstrictors and a decreased response to vasodilators.1 Presently, the mechanisms responsible for this augmented responsiveness are not clear. Potential sites of modification in vascular tissue that could lead to increased responsiveness include increased number or affinity of agonist receptors, altered function or number of intramembrane signal transduction molecules (ie, G proteins), elevated function of intracellular secondmessenger-generating enzymes, and enhanced sensitivity of contractile proteins to second-messenger signals.Previous studies have shown that although receptor upregulation occurs in some models of hypertension, it is not sufficient to explain the differences in contractility.2 Furthermore, the sensitivity of contractile proteins to calcium is not elevated in genetic hypertension in the rat, 3 nor is there a difference in the function of secondmessenger-generating enzymes 4 -5 or in the amount of G proteins present in vascular smooth muscle of hypertensive rats.6 ' 7 However, the function of G proteins in vascular tissue has not been compared between hypertensive and normotensive animals.The purpose of this study was to examine the function of G proteins in isolated vascular tissue from hypertenFrom the Department of Physiology, University of Michigan Medical School, Ann Arbor.Correspondence to Nancy L. Kanagy, PhD, Department of Physiology, University of Michigan Medical School, Ann Arbor, MI 48109-0622. sponse), whereas pertussis toxin treatment did not. Inhibition of phospholipase C also significantly decreased the mastoparan-induced response (23 ±12% of control), and nifedipine (10~3 mol/L), a calcium channel blocker, completely blocked the mastoparan-induced contraction. Indomethacin treatment did not affect the mastoparan contraction even though mastoparan has been shown to stimulate phosphol...

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Mastoparan inhibits phosphoinositide hydrolysis via pertussis toxin‐intensive G‐protein in human astrocytoma cells

Cited by 51 publications

References 17 publications

Histamine H1 receptors in C6 glial cells are coupled to calcium-dependent potassium channels via release of calcium from internal stores

Histamine H1 receptors in C6 glial cells are coupled to calcium-dependent potassium channels via release of calcium from internal stores

Mastoparan Changes the Cellular Localization of Gα_q/11and Gβ through Its Binding to Ganglioside in Lipid Rafts

Enhanced vascular reactivity to mastoparan, a G protein activator, in genetically hypertensive rats.

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Mastoparan inhibits phosphoinositide hydrolysis via pertussis toxin‐intensive G‐protein in human astrocytoma cells

Cited by 51 publications

References 17 publications

Histamine H1 receptors in C6 glial cells are coupled to calcium-dependent potassium channels via release of calcium from internal stores

Histamine H1 receptors in C6 glial cells are coupled to calcium-dependent potassium channels via release of calcium from internal stores

Mastoparan Changes the Cellular Localization of Gαq/11and Gβ through Its Binding to Ganglioside in Lipid Rafts

Enhanced vascular reactivity to mastoparan, a G protein activator, in genetically hypertensive rats.

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Mastoparan Changes the Cellular Localization of Gα_q/11and Gβ through Its Binding to Ganglioside in Lipid Rafts