Phospholipase Cγ2 Is Essential for Specific Functions of FcεR and FcγR

Wen, Renren; Jou, Shiann‐Tarng; Chen, Yuhong; Hoffmeyer, Angelica; Wang, Demin

doi:10.4049/jimmunol.169.12.6743

Cited by 71 publications

(79 citation statements)

References 91 publications

(81 reference statements)

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“…The functional defects observed in mice deficient in PLC␥ 2 are not restricted to B cells but are also observed in platelets, natural killer cells, monocytes/macrophages, and mast cells (60,61 There was no effect, however, of activated Cdc42 on PLC␥ 1 activity upon reconstitution of the two purified proteins in a cell-free system (65). At first glance, these findings are not easily consistent with the findings reported here.…”

Section: Discussioncontrasting

confidence: 55%

Isozyme-specific Stimulation of Phospholipase C-γ2 by Rac GTPases

Piechulek

Rehlen

Walliser

et al. 2005

Journal of Biological Chemistry

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The regulation of the two isoforms of phospholipase C-␥, PLC␥ 1 and PLC␥ 2 , by cell surface receptors involves protein tyrosine phosphorylation as well as interaction with adapter proteins and phosphatidylinositol 3,4,5-trisphosphate (PtdInsP 3 ) generated by inositol phospholipid 3-kinases (PI3Ks). All three processes may lead to recruitment of the PLC␥ isozymes to the plasma membrane and/or stimulation of their catalytic activity. Recent evidence suggests that PLC␥ may also be regulated by Rho GTPases. In this study, PLC␥ 1 and PLC␥ 2 were reconstituted in intact cells and in a cell-free system with Rho GTPases to examine their influence on PLC␥ activity. PLC␥ 2 , but not PLC␥ 1 , was markedly activated in intact cells by constitutively active Rac1 G12V , Rac2 G12V , and Rac3 G12V but not by Cdc42 G12V and RhoA G14V . The mechanism of PLC␥ 2 activation was apparently independent of phosphorylation of tyrosine residues known to be modified by PLC␥ 2 -activating protein-tyrosine kinases. Activation of PLC␥ 2 by Rac2 G12V in intact cells coincided with a translocation of PLC␥ 2 from the soluble to the particulate fraction. PLC␥ isozyme-specific activation of PLC␥ 2 by Rac GTPases (Rac1 ≈ Rac2 > Rac3), but not by Cdc42 or RhoA, was also observed in a cell-free system. Herein, activation of wild-type Rac GTPases with guanosine 5-(3-O-thio)triphosphate caused a marked stimulation of PLC␥ 2 but had no effect on the activity of PLC␥ 1 . PLC␥ 1 and PLC␥ 2 have previously been shown to be indiscriminately activated by PtdInsP 3 in vitro. Thus, the results suggest a novel mechanism of PLC␥ 2 activation by Rac GTPases involving neither protein tyrosine phosphorylation nor PI3K-mediated generation of PtdInsP 3 .Inositol phospholipid-specific phospholipases C (PLCs) 3 catalyze the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdInsP 2 ) to produce inositol 1,4,5-trisphosphate and diacylglycerol. While the products of this reaction have long been known to act as intracellular second messengers (reviewed in Refs. 1-4), it has only recently become clear that the phospholipid substrate itself may also be considered an intracellular signaling molecule in that its local concentration in the plasma membrane and possibly in other cellular membranes regulates the activities and/or subcellular distribution of a number of regulatory or structural proteins. These include enzymes, ion channels and transporters, transcription factors, scaffolding proteins, cytoskeletal proteins, as well as proteins involved in the regulation of exocytosis, endocytosis, and membrane trafficking (reviewed in Refs. 5-8).The mammalian PLCs are divided into six subfamilies, designated ␤, ␥, ␦, ⑀, , and (reviewed in Refs. 9 and 10). The four members of the PLC␤ subfamily are activated by ␤␥ dimers of heterotrimeric G proteins and/or members of the ␣ q subfamily of G protein ␣ subunits and by certain Rho GTPases (11-14). The two members of the PLC␥ family are activated by receptor and nonreceptor protein-tyrosine kinases (reviewed in Refs. 9, 10, 15, ...

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Section: Discussioncontrasting

confidence: 55%

Isozyme-specific Stimulation of Phospholipase C-γ2 by Rac GTPases

Piechulek

Rehlen

Walliser

et al. 2005

Journal of Biological Chemistry

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“…Previous studies indeed have shown that PLC␥2 deficiency affect cytokine secretion in monocytes (32). To differentiate between these two possibilities, we measured cytokine production by intracellular staining in PLC␥2-deficient NK cells following either anti-NKG2D or anti-NK1.1 mAbs stimulation.…”

Section: Nk Cells From Plc␥2 ϫ/ϫ Mice Fail To Generate Cytokines Andmentioning

confidence: 99%

“…In brief, 10 ϫ 10 6 purified NK cells were stimulated with soluble anti-NKG2D (20 g/ml) followed by cross-linking with 10 g of the appropriate secondary IgG Ab (Jackson ImmunoResearch Laboratories) per ml. After incubation at 37°C for 5 min, the cells were washed in PBS containing 10 mM Na 3 VO 4 , lysed in ice-cold lysis buffer, and immunoprecipitated with either anti-PLC ␥1 or anti-PLC␥2 Ab (32). The precipitates were subjected to 8% SDS-PAGE and transferred to nitrocellulose membranes.…”

Section: Immunoprecipitations and Western Blottingmentioning

confidence: 99%

“…Soluble proteins were resolved using 8% SDS-PAGE gels, transferred to nitrocellulose membranes, and probed with antisera specific for PLC␥1 or PLC␥2 (Santa Cruz Biotechnology). Western blotting for phosphorylated PLC␥1 or PLC␥2 proteins was performed as previously described (32). In brief, 10 ϫ 10 6 purified NK cells were stimulated with soluble anti-NKG2D (20 g/ml) followed by cross-linking with 10 g of the appropriate secondary IgG Ab (Jackson ImmunoResearch Laboratories) per ml.…”

Section: Immunoprecipitations and Western Blottingmentioning

confidence: 99%

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Differential and Nonredundant Roles of Phospholipase Cγ2 and Phospholipase Cγ1 in the Terminal Maturation of NK Cells

Regunathan

Chen

Kutlesa

et al. 2006

The Journal of Immunology

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NK cells play a central role in mediating innate immune responses. Activation of NK cells results in cytotoxicity, cytokine, and chemokine secretions. In this study, we show that in mice with targeted deletion of phospholipase Cγ (PLCγ)2, one of the key signal transducers, there are profound effects on the development and terminal maturation of NK cells. Lack of PLCγ2 significantly impaired the ability of lineage-committed NK precursor cells to acquire subset-specific Ly49 receptors and thereby terminal maturation of NK cells. Overexpression of isozyme, PLCγ1, in PLCγ2-deficient NK cells resulted in the successful Ly49 acquisition and terminal maturation of the NK cells; however, it could only partially rescue NKG2D-mediated cytotoxicity with no cytokine production. Furthermore, PLCγ2-deficient NK cells failed to mediate antitumor cytotoxicity and inflammatory cytokine production, displaying a generalized hyporesponsiveness. Our results strongly demonstrate that PLCγ1 and PLCγ2 play nonredundant and obligatory roles in NK cell ontogeny and in its effector functions.

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“…The calcium response results from the recruitment and activation of PLC-γ1 and/or 2, depending on the cell type Wen et al, 2002). The recruitment of PLC-γ involves the interaction of one of its SH2 domain with phosphorylated Y136 on LAT, and the interaction with the adapter Gads which binds to phosphorylated LAT terminal tyrosines.…”

Section: Intracellular Propagation Of Fcr Signalsmentioning

confidence: 99%

Negative Signaling in Fc Receptor Complexes

Daëron

Lesourne

2006

Advances in Immunology

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Cell activation results from the transient displacement of an active balance between positive and negative signaling. This displacement depends in part on the engagement of cell surface receptors by extracellular ligands. Among these are Receptors for the Fc portion of immunoglobulins (FcRs). FcRs are widely expressed by cells of hematopoietic orign. When binding antibodies, FcRs provide these cells with immunoreceptors capable of triggering numerous biological responses in response to specific antigen. FcR-dependent cell activation is regulated by negative signals which are generated together with positive signals within signalosomes that form upon FcR engagement. Many molecules involved in positive signaling, including the FcRβ subunit, the src kinase lyn, the cytosolic adapter Grb2, the transmembrane adapters LAT and NTAL, are indeed also involved in negative signaling. A major player in negative regulation of FcR signaling is the inositol 5-phosphatase SHIP1. Several layers of negative regulation operate sequentially as FcRs are engaged by extracellular ligands of increasing valency. A background protein tyrosine phosphatasedependent negative regulation maintains cells in a « resting » state. SHIP1-dependent negative regulation can be detected as soon as high-affinity FcRs are occupied by antibodies in the absence of antigen. It increases when activating FcRs are engaged by multivalent ligands and, further when FcR aggregation increases, accounting for the bell-shaped dose-response curve observed in excess of ligand. Finally, F-actin skeleton-associated high-molecular weight SHIP1, recruited to phopshorylated ITIMs, concentrates in signaling complexes when activating FcRs are coengaged with inhibitory FcRs by immune complexes. Based on these data, activating and inhibitory FcRs could be used for new therapeutic approaches of immune disorders.

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Phospholipase Cγ2 Is Essential for Specific Functions of FcεR and FcγR

Cited by 71 publications

References 91 publications

Isozyme-specific Stimulation of Phospholipase C-γ2 by Rac GTPases

Isozyme-specific Stimulation of Phospholipase C-γ2 by Rac GTPases

Differential and Nonredundant Roles of Phospholipase Cγ2 and Phospholipase Cγ1 in the Terminal Maturation of NK Cells

Negative Signaling in Fc Receptor Complexes

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