Gq Signaling Is Required for Allergen-Induced Pulmonary Eosinophilia

Borchers, Michael T.; Justice, Paul J.; Ansay, Tracy; Mancino, Valeria; McGarry, Michael P.; Crosby, Jeff; Simon, Melvin I.; Lee, Nancy A.; Lee, James J.

doi:10.4049/jimmunol.168.7.3543

Cited by 18 publications

(6 citation statements)

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“…To exmine the role of Gαq in immune responses in a primary T‐cell model we used the Gαq −/− mouse. Previous studies of Gαq −/− mice had shown that they had normal haematopoiesis and no difference in IL‐4 and INF‐γ secretion from activated T cells 28, 31. Interestingly, T cells isolated from the spleens of Gαq −/− mice secreted two‐ to threefold more IL‐2, IL‐5, IL‐12 and TNF‐α than T cells from WT mice following stimulation with anti‐CD3/anti‐CD28 beads (mean±SEM; n =4, p <0.05), but displayed no significant difference in levels of secreted IL‐4 and INF‐γ although these cytokines also tended to increase (Fig.…”

Section: Resultsmentioning

confidence: 97%

“…Gαq −/− mice and Gα11 −/− mice were bred as described previously 31, 48 in the animal house of the University of Heidelberg with permission to Stefan Offermans/Nina Wettschureck from the local authorities (Regierungspräsidium Karlsruhe). CD3 + T cells were isolated from cell suspensions of ground mouse spleens by negative selection using Dynal Mouse T Cell Negative Isolation Kit.…”

Section: Methodsmentioning

confidence: 99%

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The heterotrimeric G‐protein α‐subunit Gαq regulates TCR‐mediated immune responses through an Lck‐dependent pathway

et al. 2008

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Here, we examined the functional involvement of heterotrimeric G-proteins in TCR-induced immune responses. TCR/CD3 crosslinking resulted in activation of both Gaq and Gas, but not Gai-2. Targeting of Gas, Gai-2 and Gaq using siRNA demonstrated a specific role of Gaq in TCR signaling. Jurkat TAg T cells with Gaq knockdown displayed reduced activation of Lck and LAT phosphorylation, but paradoxically showed sustained ERK1/2 phosphorylation and increased NFAT-AP-1-reporter activity implicating Gaq in the negative control of downstream signaling and IL-2-promoter activity. Primary T cells isolated from Gaq-deficient mice had a similar TCR signaling response with reduced proximal LAT phosphorylation, sustained ERK1/2 phosphorylation and augmented immune responses including increased secretion of IL-2, IL-5, IL-12 and TNF-a. The effects on NFAT-AP-1-reporter activity were sensitive to the Src family kinase inhibitor PP2 and were reversed by transient expression of constitutively active Lck. Furthermore, expression of constitutively active Gaq Q209L elevated Lck activity and Zap-70 phosphorylation. Together these data argue for a role of Gaq in the fine-tuning of proximal TCR signals at the level of Lck and a negative regulatory role of Gaq in transcriptional activation of cytokine responses. Key words: Signal transduction . T cells . TCR . Transgenic/knockout mice IntroductionThe TCR/CD3 complex is composed of a ligand-binding TCR-ab heterodimer and signal transducing dimers of CD3eg, CD3ed and zz that upon interaction with its MHC-peptide ligand initiate an activation process that, although not fully understood, probably involves both receptor clustering and conformational changes of the cytoplasmic part of the CD3 complex [1,2]. Considering the physiological significance of correct T-cell activation, this signal interpretation probably involves complex molecular integration proximal to the TCR. A key early event is the mobilization and activation of the protein tyrosine kinase Lck, which in turn phosphorylates ITAM within the CD3 component that can recruit ZAP-70 through its two SH2-domains [3]. ZAP-70 is then phosphorylated by Lck on Y493 leading to full catalytic activation [4]. One important substrate of activated ZAP-70 is the transmembrane adaptor LAT, which acts as a scaffold to assemble signaling complexes essential for T-cell activation [5].The 3208TCR necessary for the development and activation of T cells. In addition, several lines of evidence suggest that initiation of modulating pathways is controlled by Lck. Both TCR desensitization by internalization and induction of apoptosis through the mitochondrial death pathway are regulated by Lck [7,8]. Furthermore, the activation of Lck by partial antagonist and the ability of Lck to negatively regulate superantigen-induced T-cell activation support a dual role of Lck [9,10]. Interestingly, acute elimination of Lck in either Jurkat or primary T cells using RNA interference results in sustained and elevated ERK1/2 phosphorylation and augmented NFAT-reporter ac...

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Section: Resultsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

The heterotrimeric G‐protein α‐subunit Gαq regulates TCR‐mediated immune responses through an Lck‐dependent pathway

et al. 2008

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“…However, there are several reasons that can explain the apparent discrepancy between the older studies and the current study. First, given the critical importance of Gi in both the classical and alternative chemokine receptor signaling pathways, it is not possible to visualize the alternative signaling pathway unless Gα q is selectively targeted in a Gα i2 -sufficient cell and, to our knowledge, only a single study examining Gα q -deficient leukocytes has been published ( 63 ). Second, many of the previous biochemical studies analyzed signaling through CXCR1/CXCR2, the receptors for IL-8 and Mip2 ( 5 – 7 , 48 ).…”

Section: Discussionmentioning

confidence: 99%

Identification of an alternative Gαq-dependent chemokine receptor signal transduction pathway in dendritic cells and granulocytes

Shi

Partida-Sánchez

Misra

et al. 2007

The Journal of Experimental Medicine

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CD38 controls the chemotaxis of leukocytes to some, but not all, chemokines, suggesting that chemokine receptor signaling in leukocytes is more diverse than previously appreciated. To determine the basis for this signaling heterogeneity, we examined the chemokine receptors that signal in a CD38-dependent manner and identified a novel “alternative” chemokine receptor signaling pathway. Similar to the “classical” signaling pathway, the alternative chemokine receptor pathway is activated by Gαi2-containing Gi proteins. However, unlike the classical pathway, the alternative pathway is also dependent on the Gq class of G proteins. We show that Gαq-deficient neutrophils and dendritic cells (DCs) make defective calcium and chemotactic responses upon stimulation with N-formyl methionyl leucyl phenylalanine and CC chemokine ligand (CCL) 3 (neutrophils), or upon stimulation with CCL2, CCL19, CCL21, and CXC chemokine ligand (CXCL) 12 (DCs). In contrast, Gαq-deficient T cell responses to CXCL12 and CCL19 remain intact. Thus, the alternative chemokine receptor pathway controls the migration of only a subset of cells. Regardless, the novel alternative chemokine receptor signaling pathway appears to be critically important for the initiation of inflammatory responses, as Gαq is required for the migration of DCs from the skin to draining lymph nodes after fluorescein isothiocyanate sensitization and the emigration of monocytes from the bone marrow into inflamed skin after contact sensitization.

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“…Eosinophils were isolated from the spleens of naïve IL-5-TG mice, following the method previously described for isolating them from blood (2). In brief, single-cell suspensions of spleens were layered onto a Percoll gradient (60% Percoll [ ϭ 1.084] 1ϫ Hanks balanced salt solution, 15 mM HEPES [pH 7.4], and 0.003 N HCl) and centrifuged (45 min, 1,200 ϫ g, 4°C).…”

Section: Methodsmentioning

confidence: 99%

Eosinophils Can Function as Antigen-Presenting Cells To Induce Primary and Secondary Immune Responses toStrongyloides stercoralis

et al. 2006

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Several studies have demonstrated roles for eosinophils during innate and adaptive immune responses to helminth infections. However, evidence that eosinophils are capable of initiating an immune response to parasite antigens is lacking. The goal of the present in vitro study was to investigate the potential of eosinophils to serve as antigen-presenting cells (APC) and initiate an immune response to parasite antigens. Purified eosinophils were exposed to soluble Strongyloides stercoralis antigens, and the expression of various surface markers involved in cell activation was examined. Antigen-exposed eosinophils showed a sixfold increase in expression levels of CD69 and major histocompatibility complex (MHC) class II, a fourfold increase in levels of T-cell costimulatory molecule CD86, and a twofold decrease in levels of CD62L compared to eosinophils cultured in medium containing granulocyte-macrophage colony-stimulating factor. The ability of eosinophils to present antigen to T cells was determined by culturing them with T cells in vitro. Eosinophils pulsed with antigen stimulated antigen-specific primed T cells and CD4 ؉ T cells to increase interleukin-5 (IL-5) production. The blocking of MHC class II expression on eosinophils inhibited their ability to induce IL-5 production by CD4؉ T cells in culture. Antigen-pulsed eosinophils were able to prime naïve T cells and CD4 ؉ T cells in culture and polarized them into Th2 cells producing IL-5 similar to that induced by antigen-loaded dendritic cells. These results demonstrate that eosinophils are capable of activating antigen-specific Th2 cells inducing the release of cytokines and assist in the priming of naïve T cells to initiate Th2 responses against infection. This study highlights the potential of eosinophils to actively induce immune responses against infection by amplifying antigen-specific Th2-cell responses.

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Gq Signaling Is Required for Allergen-Induced Pulmonary Eosinophilia

Cited by 18 publications

References 50 publications

The heterotrimeric G‐protein α‐subunit Gαq regulates TCR‐mediated immune responses through an Lck‐dependent pathway

The heterotrimeric G‐protein α‐subunit Gαq regulates TCR‐mediated immune responses through an Lck‐dependent pathway

Identification of an alternative Gαq-dependent chemokine receptor signal transduction pathway in dendritic cells and granulocytes

Eosinophils Can Function as Antigen-Presenting Cells To Induce Primary and Secondary Immune Responses toStrongyloides stercoralis

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