0000000000349364

AUTHOR

Ulrich Rümenapp

showing 4 related works from this author

A role for Rho in receptor- and G protein-stimulated phospholipase C Reduction in phosphatidylinositol 4,5-bisphosphate by Clostridium difficile toxi…

1996

Receptors coupled to heterotrimeric guanine nucleotide-binding proteins (G proteins) activate phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2)-hydrolyzing phospholipase C (PLC) enzymes by activated alpha of free beta gamma subunits of the relevant G proteins. To study whether low molecular weight G proteins of the Rho family are involved in receptor signaling to PLC, we examined the effect of Clostridium difficile toxin B, which glucosylates and thereby inactivates Rho proteins, on the regulation of PLC activity in human embryonic kidney (HEK) cells stably expressing the m3 muscarinic acetylcholine receptor (mAChR) subtype. Toxin B treatment of HEK cells did not affect basal PLC activi…

Phosphatidylinositol 45-DiphosphateBotulinum ToxinsG proteinBacterial ToxinsClostridium difficile toxin AClostridium difficile toxin BBiologychemistry.chemical_compoundBacterial ProteinsGTP-Binding ProteinsHeterotrimeric G proteinHumansPhosphatidylinositolCells CulturedADP Ribose TransferasesPharmacologyPhospholipase CHEK 293 cellsGeneral MedicineReceptors MuscarinicMolecular biologyCell biologychemistryPhosphatidylinositol 45-bisphosphateType C PhospholipasesrhoA GTP-Binding ProteinNaunyn-Schmiedeberg's Archives of Pharmacology
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Inhibition of Receptor Signaling to Phospholipase D by Clostridium difficile Toxin B

1996

Rho proteins have been reported to activate phospholipase D (PLD) in in vitro preparations. To examine the role of Rho proteins in receptor signaling to PLD, we studied the effect of Clostridium difficile toxin B, which glucosylates Rho proteins, on the regulation of PLD activity in human embryonic kidney (HEK) cells stably expressing the m3 muscarinic acetylcholine receptor (mAChR). Toxin B treatment of HEK cells potently and efficiently blocked mAChR-stimulated PLD. In contrast, basal and phorbol ester-stimulated PLD activities were not or only slightly reduced. Cytochalasin B and Clostridium botulinum C2 toxin, mimicking the effect of toxin B on the actin cytoskeleton but without involvi…

Phospholipase DG proteinClostridium difficile toxin AClostridium difficile toxin BCell BiologyBiologymedicine.disease_causeActin cytoskeletonBiochemistryMolecular biologyenzymes and coenzymes (carbohydrates)chemistry.chemical_compoundchemistrymedicineClostridium botulinumlipids (amino acids peptides and proteins)Signal transductionMolecular BiologyCytochalasin BJournal of Biological Chemistry
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Tyrosine-phosphorylation-dependent and Rho-protein-mediated control of cellular phosphatidylinositol 4,5-bisphosphate levels

1998

The polyphosphoinositide PtdIns(4,5)P2, best known as a substrate for phospholipase C isozymes, has recently been recognized to be involved in a variety of other cellular processes. The aim of this study was to examine whether the cellular levels of this versatile phospholipid are controlled by tyrosine phosphorylation. The studies were performed in human embryonic kidney (HEK)-293 cells stably expressing the M3 muscarinic acetylcholine receptor. Inhibition of tyrosine phosphatases by pervanadate induced an up-to-approx.-2.5-fold increase in the total cellular level of PtdIns(4,5)P2, which was both time- and concentration-dependent. In contrast, the tyrosine kinase inhibitors, genistein and…

Phosphatidylinositol 45-DiphosphateBacterial ToxinsBiologyBiochemistryCell LineGTP Phosphohydrolaseschemistry.chemical_compoundEnzyme activatorBacterial ProteinsGTP-Binding ProteinsPhospholipase DHumansPhosphorylationTyrosinerhoB GTP-Binding ProteinMolecular BiologyPhospholipase CADP-Ribosylation FactorsClostridioides difficilePhospholipase DMembrane ProteinsTyrosine phosphorylationCell BiologyTyrphostinsGenisteinCell biologyEnzyme ActivationBiochemistryPhosphatidylinositol 45-bisphosphatechemistryTyrosinePhosphorylationVanadatesTyrosine kinaseResearch ArticleBiochemical Journal
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Restoration of Clostridium difficile toxin-B-inhibited phospholipase D by phosphatidylinositol 4,5-bisphosphate.

1996

Receptor signalling to phospholipase D (PLD) in human embryonic kidney (HEK) cells stably expressing the m3 muscarinic acetylcholine receptor apparently involves Rho proteins. Since phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] has been recognized as an essential cofactor for PLD activity and since activated Rho proteins have been reported to stimulate the synthesis of PtdIns(4,5)P2, we studied whether in HEK cells PLD activity is regulated by PtdIns(4,5)P2 and, in particular, whether PtdIns(4,5)P2 can restore PLD activity inhibited by Clostridium difficile toxin B, which inactivates Rho proteins. Addition of MgATP to permeabilized HEK cells increased basal PLD activity and potentia…

Phosphatidylinositol 45-DiphosphateGTP'Bacterial ToxinsClostridium difficile toxin BBiologyBiochemistryCell Linechemistry.chemical_compoundBacterial ProteinsGTP-Binding ProteinsPhosphatidylcholineRhoB GTP-Binding ProteinPhospholipase DHumansPhosphatidylinositolEnzyme InhibitorsrhoB GTP-Binding ProteinPhospholipase DClostridioides difficileHEK 293 cellsCell MembraneMembrane ProteinsReceptors MuscarinicCell biologyEnzyme Activationenzymes and coenzymes (carbohydrates)chemistryPhosphatidylinositol 45-bisphosphateGuanosine 5'-O-(3-Thiotriphosphate)lipids (amino acids peptides and proteins)European journal of biochemistry
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