title: Rac-mediated Stimulation of Phospholipase Cγ2 Amplifies B Cell Receptor-induced Calcium Signaling.
abstract: The Rho GTPase Rac is crucially involved in controlling multiple B cell functions, including those regulated by the B cell receptor (BCR) through increased cytosolic Ca(2+). The underlying molecular mechanisms and their relevance to the functions of intact B cells have thus far remained unknown. We have previously shown that the activity of phospholipase Cγ2 (PLCγ2), a key constituent of the BCR signalosome, is stimulated by activated Rac through direct protein-protein interaction. Here, we use a Rac-resistant mutant of PLCγ2 to functionally reconstitute cultured PLCγ2-deficient DT40 B cells and to examine the effects of the Rac-PLCγ2 interaction on BCR-mediated changes of intracellular Ca(2+) and regulation of Ca(2+)-regulated and nuclear-factor-of-activated-T-cell-regulated gene transcription at the level of single, intact B cells. The results show that the functional Rac-PLCγ2 interaction causes marked increases in the following: (i) sensitivity of B cells to BCR ligation; (ii) BCR-mediated Ca(2+) release from intracellular stores; (iii) Ca(2+) entry from the extracellular compartment; and (iv) nuclear translocation of the Ca(2+)-regulated nuclear factor of activated T cells. Hence, Rac-mediated stimulation of PLCγ2 activity serves to amplify B cell receptor-induced Ca(2+) signaling.
authors.affiliation: From the Institute of Pharmacology and Toxicology, University of Ulm Medical Center, 89070 Ulm, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Walliser
authors.affiliation: the Institute of Biophysics, University of Ulm, 89069 Ulm, Germany.
authors.forename: Kyrylo
authors.initials: K
authors.lastname: Tron
authors.affiliation: the Institute of Biophysics, University of Ulm, 89069 Ulm, Germany.
authors.forename: Karen
authors.initials: K
authors.lastname: Clauss
authors.affiliation: the Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Orit
authors.initials: O
authors.lastname: Gutman
authors.affiliation: the Institute of Applied Physics and Center for Functional Nanostructures, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
authors.forename: Andrei Yu
authors.initials: AY
authors.lastname: Kobitski
authors.affiliation: From the Institute of Pharmacology and Toxicology, University of Ulm Medical Center, 89070 Ulm, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Retlich
authors.affiliation: From the Institute of Pharmacology and Toxicology, University of Ulm Medical Center, 89070 Ulm, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Schade
authors.affiliation: the Institute of Biophysics, University of Ulm, 89069 Ulm, Germany.
authors.forename: Carlheinz
authors.initials: C
authors.lastname: Röcker
authors.affiliation: the Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Yoav I
authors.initials: YI
authors.lastname: Henis
authors.affiliation: the Institute of Applied Physics and Center for Functional Nanostructures, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany, the Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany, and the Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.
authors.forename: G Ulrich
authors.initials: GU
authors.lastname: Nienhaus
authors.affiliation: From the Institute of Pharmacology and Toxicology, University of Ulm Medical Center, 89070 Ulm, Germany, peter.gierschik@uni-ulm.de.
authors.forename: Peter
authors.initials: P
authors.lastname: Gierschik
mesh_terms: D021581:Active Transport, Cell Nucleus; D019943:Amino Acid Substitution; D000818:Animals; D030161:Avian Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D002460:Cell Line; D002645:Chickens; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D050778:NFATC Transcription Factors / Q000378:metabolism; D051966:Phospholipase C gamma / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020744:rac GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D030161:Avian Proteins; D050778:NFATC Transcription Factors; D011947:Receptors, Antigen, B-Cell; D011994:Recombinant Proteins; D051966:Phospholipase C gamma; D020744:rac GTP-Binding Proteins
keywords: B cell; Rac (Rac GTPase); calcium; lymphocyte; phospholipase C; signal amplification; signal transduction