scholarly journals Inhibitory receptor FcγRIIb mediates the effects of IgG on a phagosome acidification and a sequential dephosphorylation system comprising SHIPs and Inpp4a

2017 ◽  
Vol 23 (4) ◽  
pp. 401-409 ◽  
Author(s):  
Tomohiro Segawa ◽  
Kaoru Hazeki ◽  
Kiyomi Nigorikawa ◽  
Atsuko Nukuda ◽  
Tomoki Tanizawa ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Fluorescence Probe ◽  
Pleckstrin Homology Domain ◽  
Raw 264.7 Macrophages ◽  
Lipid Phosphatases ◽  
Src Homology 2 ◽  
Lipid Phosphatase ◽  
Src Homology ◽  
Src Homology 2 Domain ◽  
Green Fluorescent

The relative abundance of phosphoinositide (PI) species on the phagosome membrane fluctuates over the course of phagocytosis. PtdIns(3,4,5)P3 and PtdIns(3,4)P2 rapidly increase in the forming of the phagocytic cup, following which they disappear after sealing of the cup. In the present study, we monitored the clearance of these PI species using the enhanced green fluorescent protein-fused pleckstrin homology domain of Akt, a fluorescence probe that binds both PtdIns(3,4,5)P3 and PtdIns(3,4)P2 in Raw 264.7 macrophages. The clearance of PIs was much faster when the phagocytosed particles were coated with IgG. The effect of IgG was not observed in the macrophages deficient in FcγRIIb, an inhibitory IgG receptor. To identify the lipid phosphatases responsible for the FcγRIIb-accelerated PI clearance, we prepared a panel of lipid phosphatase-deficient cells. The lack of a PI 5-phosphatase Src homology 2 domain-containing inositol-5-phosphatase (SHIP)1 or SHIP2 impaired the FcγRIIb-accelerated clearance of PIs. The lack of a PI 4-phosphatase Inpp4a also impaired the accelerated PIs clearance. In the FcγRIIb- and Inpp4a-deficient cells, acidification of the formed phagosome was slowed. These results suggested that FcγRIIb drives the sequential dephosphorylation system comprising SHIPs and Inpp4a, and accelerates phagosome acidification.

Non-invasive visualization of the lipid product of class I PI3K in transgenic mouse models

2007 ◽  
Vol 35 (2) ◽  
pp. 215-218 ◽  
Author(s):  
T. Sasaki ◽  
J. Sasaki ◽  
K. Watanabe ◽  
A. Suzuki
Keyword(s):  
Transgenic Mice ◽  
Fluorescent Protein ◽  
Neutrophil Migration ◽  
Pleckstrin Homology Domain ◽  
Inositol Phosphatase ◽  
Lipid Product ◽  
Src Homology ◽  
Spatio Temporal ◽  
Metabolizing Enzyme ◽  
Green Fluorescent

PI3Ks (phosphoinositide 3-kinases) regulate many critical cellular responses by producing PI(3,4,5)P3 (phosphatidylinositol 3,4,5-trisphosphate). To facilitate the spatio-temporal characterization of PI(3,4,5)P3 in living primary cells, we generated a novel strain of transgenic mice [AktPH (Akt pleckstrin homology domain)–GFP (green fluorescent protein) Tg (transgenic) mice] that express a fluorescent bioprobe for PI(3,4,5)P3/PI(3,4)P2 (phosphatidylinositol 3,4-bisphosphate). By crossing AktPH–GFP Tg mice with strains of gene-targeted ‘knockout’ mice lacking a particular phosphoinositide-metabolizing enzyme, we have been able to evaluate the contribution of each enzyme to PI(3,4,5)P3 localization in migrating neutrophils. Our results indicate that PI3Kγ and the PI(3,4,5)P3 phosphatase SHIP1 [SH2 (Src homology 2)-containing inositol phosphatase-1] are the key regulators of PI(3,4,5)P3 dynamics during fMet-Leu-Phe (N-formylmethionyl-leucylphenylalanine; ‘chemotactic peptide’)-stimulated neutrophil migration. Our study has also validated the fluorescent transgenic strategy for studying PI(3,4,5)P3 metabolism in physiological and pathological situations.

scholarly journals Hsp90 Is Essential for the Synthesis and Subsequent Membrane Association, But Not the Maintenance, of the Src-Kinase p56lck

2000 ◽  
Vol 11 (5) ◽  
pp. 1585-1595 ◽  
Author(s):  
Marie-José J. E. Bijlmakers ◽  
Mark Marsh
Keyword(s):  
Tyrosine Kinases ◽  
Fluorescent Protein ◽  
Membrane Binding ◽  
Src Kinase ◽  
Direct Role ◽  
Hsp90 Activity ◽  
Src Homology ◽  
Src Homology 2 Domain ◽  
The Stability ◽  
Green Fluorescent

Tyrosine kinases of the Src family are synthesized as cytosolic proteins that subsequently translocate to membranes. Little is known of the mechanisms responsible for targeting these proteins to membranes, although a role for the cytosolic chaperone Hsp90 has been proposed. Here, we have studied the involvement of Hsp90 in the synthesis, membrane binding, and maintenance of the Src-kinase Lck. Using specific inhibitors of Hsp90, geldanamycin and radicicol, we found that functional Hsp90 is essential for the stability of newly synthesized, but not mature, Lck. Similar results were obtained for two other Src-kinases, c-Src and Lyn. In contrast, LckY505F and LckΔSH2, constitutively active Lck mutants lacking the C-terminal regulatory tyrosine or the entire Src homology 2 domain, respectively, required Hsp90 activity to stabilize the mature proteins. Lck synthesized in the absence of Hsp90 activity was degraded within 30–45 min. This unstable Lck was myristoylated normally but did not associate with membranes or CD4, interactions that normally start within minutes of the completion of Lck synthesis. A construct composed of the N-terminal unique domain of Lck fused to green fluorescent protein did not require Hsp90 activity during synthesis. In addition, this protein associated with membranes efficiently in the absence of Hsp90 activity. Together these data suggest that interaction with Hsp90 is necessary for the correct synthesis and subsequent membrane binding of Lck. However, Hsp90 does not appear to play a direct role in Lck membrane, or CD4, association.

scholarly journals IL-6 blocks a discrete early step in lymphopoiesis

Blood ◽  
2005 ◽  
Vol 106 (3) ◽  
pp. 879-885 ◽  
Author(s):  
Kazuhiko Maeda ◽  
Yoshihiro Baba ◽  
Yoshinori Nagai ◽  
Kozo Miyazaki ◽  
Alexander Malykhin ◽  
...  
Keyword(s):  
Target Cells ◽  
Hematopoietic Progenitors ◽  
Early Step ◽  
Hematopoietic Stem ◽  
Lymphoid Lineage ◽  
Src Homology 2 ◽  
Multipotent Progenitors ◽  
Src Homology ◽  
Src Homology 2 Domain

Abstract Animals lacking Src homology 2 domain-containing inositol 5-phosphatase (SHIP) display a reduction in lymphopoiesis and a corresponding enhancement of myelopoiesis. These effects are mediated at least in part by elevated levels of interleukin 6 (IL-6). Here, we show the lymphopoiesis block in SHIP–/– mice is due to suppression of the lymphoid lineage choice by uncommitted progenitors. The suppression can be reproduced in vitro with recombinant IL-6, and IL-6 acts directly on hematopoietic progenitors. The block is partially overcome in SHIP–/– IL-6–/– double-deficient animals. IL-6 does not suppress but actually enhances proliferation of lymphoid-committed progenitors, indicating the IL-6 target cells are hematopoietic stem cells or multipotent progenitors. The findings suggest a mechanism for the lymphopenia that accompanies proinflammatory diseases.

scholarly journals FP12.03 SRC-Homology 2 Domain-Containing Phosphatase 2 (SHP2) in Resected Lung Adenocarcinoma (LUAD)

2021 ◽  
Vol 16 (3) ◽  
pp. S217-S218
Author(s):  
M. Ito ◽  
J. Codony-Servat ◽  
A. Giménez-Capitán ◽  
M. Serra-Mitjans ◽  
F. Pérez-Ochoa ◽  
...  
Keyword(s):  
Lung Adenocarcinoma ◽  
Src Homology 2 ◽  
Src Homology ◽  
Src Homology 2 Domain

scholarly journals Integrin-linked kinase (ILK) and src homology 2 domain-containing phosphatase 2 (SHP2): Novel targets in EGFR-mutation positive non-small cell lung cancer (NSCLC)

EBioMedicine ◽  
2019 ◽  
Vol 39 ◽  
pp. 207-214 ◽  
Author(s):  
Niki Karachaliou ◽  
Andres Felipe Cardona ◽  
Jillian Wilhelmina Paulina Bracht ◽  
Erika Aldeguer ◽  
Ana Drozdowskyj ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Small Cell Lung Cancer ◽  
Egfr Mutation ◽  
Small Cell ◽  
Small Cell Lung ◽  
Src Homology 2 ◽  
Integrin Linked Kinase ◽  
Src Homology ◽  
Novel Targets ◽  
Src Homology 2 Domain
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