scholarly journals Regulation of Discrete Functional Responses by Syk and Src Family Tyrosine Kinases in Human Neutrophils

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Thornin Ear ◽  
Olga Tatsiy ◽  
Frédérick L. Allard ◽  
Patrick P. McDonald
Keyword(s):  
Translational Control ◽  
Tyrosine Kinases ◽  
Critical Role ◽  
Protein Tyrosine Kinases ◽  
Human Neutrophils ◽  
Functional Responses ◽  
Adaptive Immune ◽  
Inflammatory Conditions ◽  
Src Family Tyrosine Kinases

Neutrophils play a critical role in innate immunity and also influence adaptive immune responses. This occurs in good part through their production of inflammatory and immunomodulatory cytokines, in conjunction with their prolonged survival at inflamed foci. While a picture of the signaling machinery underlying these neutrophil responses is now emerging, much remains to be uncovered. In this study, we report that neutrophils constitutively express various Src family isoforms (STKs), as well as Syk, and that inhibition of these protein tyrosine kinases selectively hinders inflammatory cytokine generation by acting posttranscriptionally. Accordingly, STK or Syk inhibition decreases the phosphorylation of signaling intermediates (e.g., eIF-4E, S6K, and MNK1) involved in translational control. By contrast, delayed apoptosis appears to be independent of either STKs or Syk. Our data therefore significantly extend our understanding of which neutrophil responses are governed by STKs and Syk and pinpoint some signaling intermediates that are likely involved. In view of the foremost role of neutrophils in several chronic inflammatory conditions, our findings identify potential molecular targets that could be exploited for future therapeutic intervention.

scholarly journals Role of Protein Tyrosine Kinase p53/56lyn in Diminished Lipopolysaccharide Priming of Formylmethionylleucyl- phenylalanine-Induced Superoxide Production in Human Newborn Neutrophils

2004 ◽  
Vol 72 (11) ◽  
pp. 6455-6462 ◽  
Author(s):  
Sen Rong Yan ◽  
David M. Byers ◽  
Robert Bortolussi
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Protein Tyrosine Kinase ◽  
Kinase Inhibitor ◽  
Critical Role ◽  
Polymorphonuclear Neutrophils ◽  
Protein Tyrosine Kinases ◽  
Protein Tyrosine ◽  
Adult Cells

ABSTRACT Human newborns are more susceptible than adults to bacterial infection. With gram-negative bacteria, this may be due to a diminished response of newborn leukocytes to lipopolysaccharide (LPS). Since protein tyrosine kinase inhibition abolishes LPS priming in adult cells, we hypothesized that protein tyrosine kinases may have a critical role in LPS priming of polymorphonuclear neutrophils (PMNs) and that newborn PMNs may have altered protein tyrosine kinase activities. In the present study, we investigated the role of src family protein tyrosine kinases in the LPS response of newborn PMNs compared to adult cells. In a respiratory assay, the LPS-primed increase in formylmethionylleucylphenylalanine (fMLP)-triggered O2 − release by adult PMNs was greatly decreased by PP1 [4-amino-5-(4-methyphenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine], a src kinase inhibitor, to the level of untreated newborn PMNs, in which LPS failed to prime. LPS activated the src-like kinases p59hck (HCK) and p58fgr (FGR) in both adult and newborn PMNs but increased the activation of p53/56 lyn (LYN) only in adult cells. In newborn PMNs, LYN was highly phosphorylated independent of LPS. We evaluated subcellular fractions of PMNs and found that the phosphorylated form of LYN was mainly in the Triton-extractable, cytosolic fraction in adult PMNs, while in newborn cells it was located mainly in Triton-insoluble, granule- and membrane-associated fractions. In contrast, the phosphorylated mitogen-activated protein kinases ERK1/2 and p38 were mainly detected in the cytosol in both adult and newborn PMNs. These data indicate a role for LYN in the regulation of LPS priming. The trapping of phosphorylated LYN in the membrane-granule fraction in newborn PMNs may contribute to the deficiency of newborn cells in responding to LPS stimulation.

Role of protein tyrosine kinases in CD40/interleukin-4-mediated isotype switching to IgE

1994 ◽  
Vol 94 (4) ◽  
pp. 784-792 ◽  
Author(s):  
Richard K.S. Loh ◽  
Haifa H. Jabara ◽  
Clement L. Ren ◽  
Shu Man Fu ◽  
Raif S. Geha
Keyword(s):  
Tyrosine Kinases ◽  
Protein Tyrosine Kinases ◽  
Interleukin 4 ◽  
Isotype Switching ◽  
Protein Tyrosine

scholarly journals Distribution of seed dormancy classes across a fire-prone continent: effects of rainfall seasonality and temperature

2020 ◽  
Author(s):  
Justin C Collette ◽  
Mark K J Ooi
Keyword(s):  
Seed Dormancy ◽  
Critical Role ◽  
Fire Regimes ◽  
Common Species ◽  
Functional Responses ◽  
Stochastic Disturbance ◽  
Climate Gradients ◽  
Selective Pressures ◽  
Rainfall Seasonality

Abstract Background and Aims Different seed dormancy classes control the timing of germination via different cues. The ecological dissimilarities between classes therefore suggest that they are likely to be subject to different selective pressures, and that species within each class will have diverse functional responses. We aimed to investigate this by assessing how variation in the distribution of dormancy classes is correlated with regional environmental factors, in particular rainfall seasonality and temperature. Additionally, we compare the relative proportions of species with physiological (PD) or physical (PY) dormancy to assess whether dormancy class influences their ability to persist under different rainfall seasonality regimes. Methods Dormancy class was assigned for 3990 species from 281 genera occurring across two climate regions, with either winter or aseasonal rainfall, across temperate fire-prone Australia. All regions have similar vegetation and fire regimes. Using a Bayesian framework, we compared the distribution of dormancy classes across temperature and rainfall climate gradients, for threatened and common species. Key Results A high dormant:non-dormant species ratio highlighted the critical role of dormancy across our study regions. Critically, species showing PD were more likely to be threatened in aseasonal rainfall climate regions. Conclusions Our results support the assumption that dormancy is favoured in environments with stochastic disturbance

scholarly journals Exacerbated Imiquimod-Induced Psoriasis-Like Skin Inflammation in IRF5-Deficient Mice

2020 ◽  
Vol 21 (10) ◽  
pp. 3681
Author(s):  
Momoko Nakao ◽  
Tomomitsu Miyagaki ◽  
Makoto Sugaya ◽  
Shinichi Sato
Keyword(s):  
Critical Role ◽  
Skin Inflammation ◽  
Interferon Α ◽  
Toll Like Receptor ◽  
Adaptive Immune ◽  
Th17 Cytokines ◽  
Factor Α ◽  
Deficient Mice ◽  
Necrosis Factor

Interferon regulatory factors (IRFs) play diverse roles in the regulation of the innate and adaptive immune responses in various diseases. In psoriasis, IRF2 is known to be involved in pathogenesis, while studies on other IRFs are limited. In this study, we investigated the role of IRF5 in psoriasis using imiquimod-induced psoriasis-like dermatitis. Although IRF5 is known to play a critical role in the induction of proinflammatory cytokines by immune cells, such as dendritic cells (DCs), macrophages, and monocytes, IRF5 deficiency unexpectedly exacerbated psoriasiform skin inflammation. The interferon-α and tumor necrosis factor-α mRNA expression levels were decreased, while levels of Th17 cytokines including IL-17, IL-22, and IL-23 were increased in IRF5-deficient mice. Furthermore, IL-23 expression in DCs from IRF5-deficient mice was upregulated both in steady state and after toll-like receptor 7/8 agonist stimulation. Importantly, the expression of IRF4, which is also important for the IL-23 production in DCs, was augmented in DCs from IRF5-deficient mice. Taken together, our results suggest that IRF5 deficiency induces the upregulation of IRF4 in DCs followed by augmented IL-23 production, resulting in the amplification of Th17 responses and the exacerbation of imiquimod-induced psoriasis-like skin inflammation. The regulation of IRF4 or IRF5 expression may be a novel therapeutic approach to psoriasis.

Role of phosphoinositide 3-kinase β in platelet aggregation and thromboxane A2 generation mediated by Gi signalling pathways

2010 ◽  
Vol 429 (2) ◽  
pp. 369-377 ◽  
Author(s):  
Analia Garcia ◽  
Soochong Kim ◽  
Kamala Bhavaraju ◽  
Simone M. Schoenwaelder ◽  
Satya P. Kunapuli
Keyword(s):  
Platelet Aggregation ◽  
Critical Role ◽  
Thromboxane A2 ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
P2y12 Receptor ◽  
Functional Responses ◽  
Induce Platelet Aggregation ◽  
Erk Phosphorylation

PI3Ks (phosphoinositide 3-kinases) play a critical role in platelet functional responses. PI3Ks are activated upon P2Y12 receptor stimulation and generate pro-aggregatory signals. P2Y12 receptor has been shown to play a key role in the platelet aggregation and thromboxane A2 generation caused by co-stimulation with Gq or Gz, or super-stimulation of Gi pathways. In the present study, we evaluated the role of specific PI3K isoforms α, β, γ and δ in platelet aggregation, thromboxane A2 generation and ERK (extracellular-signal-regulated kinase) activation. Our results show that loss of the PI3K signal impaired the ability of ADP to induce platelet aggregation, ERK phosphorylation and thromboxane A2 generation. We also show that Gq plus Gi- or Gi plus Gz-mediated platelet aggregation, ERK phosphorylation and thromboxane A2 generation in human platelets was inhibited by TGX-221, a PI3Kβ-selective inhibitor, but not by PIK75 (a PI3Kα inhibitor), AS252424 (a PI3Kγ inhibitor) or IC87114 (a PI3Kδ inhibitor). TGX-221 also showed a similar inhibitory effect on the Gi plus Gz-mediated platelet responses in platelets from P2Y1−/− mice. Finally, 2MeSADP (2-methyl-thio-ADP)-induced Akt phosphorylation was significantly inhibited in the presence of TGX-221, suggesting a critical role for PI3Kβ in Gi-mediated signalling. Taken together, our results demonstrate that PI3Kβ plays an important role in ADP-induced platelet aggregation. Moreover, PI3Kβ mediates ADP-induced thromboxane A2 generation by regulating ERK phosphorylation.

scholarly journals Na+/H+ exchange activity during phagocytosis in human neutrophils: role of Fcgamma receptors and tyrosine kinases.

1996 ◽  
Vol 132 (6) ◽  
pp. 1037-1052 ◽  
Author(s):  
T Fukushima ◽  
T K Waddell ◽  
S Grinstein ◽  
G G Goss ◽  
J Orlowski ◽  
...  
Keyword(s):  
Tyrosine Phosphorylation ◽  
Tyrosine Kinases ◽  
Plasma Membranes ◽  
Kinase Inhibitors ◽  
Human Neutrophils ◽  
Cross Linking ◽  
Fcgamma Receptors ◽  
Beta2 Integrins ◽  
Cytosolic Acidification

In neutrophils, binding and phagocytosis facilitate subsequent intracellular killing of microorganisms. Activity of Na+/H+ exchangers (NHEs) participates in these events, especially in regulation of intracellular pH (pHi) by compensating for the H+ load generated by the respiratory burst. Despite the importance of these functions, comparatively little is known regarding the nature and regulation of NHE(s) in neutrophils. The purpose of this study was to identify which NHE(s) are expressed in neutrophils and to elucidate the mechanisms regulating their activity during phagocytosis. Exposure of cells to the phagocytic stimulus opsonized zymosan (OpZ) induced a transient cytosolic acidification followed by a prolonged alkalinization. The latter was inhibited in Na+-free medium and by amiloride analogues and therefore was due to activation of Na+/H+ exchange. Reverse transcriptase PCR and cDNA sequencing demonstrated that mRNA for the NHE-1 but not for NHE-2, 3, or 4 isoforms of the exchanger was expressed. Immunoblotting of purified plasma membranes with isoform-specific antibodies confirmed the presence of NHE-1 protein in neutrophils. Since phagocytosis involves Fcgamma (FcgammaR) and complement receptors such as CR3 (a beta2 integrin) which are linked to pathways involving alterations in intracellular [Ca2+]i and tyrosine phosphorylation, we studied these pathways in relation to activation of NHE-1. Cross-linking of surface bound antibodies (mAb) directed against FcgammaRs (FcgammaRII > FcgammaRIII) but not beta2 integrins induced an amiloride-sensitive cytosolic alkalinization. However, anti-beta2 integrin mAb diminished OpZ-induced alkalinization suggesting that NHE-1 activation involved cooperation between integrins and FcgammaRs. The tyrosine kinase inhibitors genistein and herbimycin blocked cytosolic alkalinization after OpZ or FcgammaR cross-linking suggesting that tyrosine phosphorylation was involved in NHE-I activation. An increase in [Ca2+]i was not required for NHE-1 activation because neither removal of extracellular Ca2+ nor buffering of changes in [Ca2+]i inhibited alkalinization after OpZ or Fc-gammaR cross-linking. In summary, Fc-gammaRs and beta2 integrins cooperate in activation of NHE-1 in neutrophils during phagocytosis by a signaling pathway involving tyrosine phosphorylation.

scholarly journals Crosstalk between Dendritic Cells and Immune Modulatory Agents against Sepsis

Genes ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 323 ◽  
Author(s):  
Guoying Wang ◽  
Xianghui Li ◽  
Lei Zhang ◽  
Abualgasim Elgaili Abdalla ◽  
Tieshan Teng ◽  
...  
Keyword(s):  
Immune Response ◽  
Dendritic Cells ◽  
Immune Responses ◽  
Critical Role ◽  
Innate Immune ◽  
Adaptive Immune Responses ◽  
Adaptive Immune ◽  
Th2 Responses ◽  
Novel Strategy

Dendritic cells (DCs) play a critical role in the immune system which sense pathogens and present their antigens to prime the adaptive immune responses. As the progression of sepsis occurs, DCs are capable of orchestrating the aberrant innate immune response by sustaining the Th1/Th2 responses that are essential for host survival. Hence, an in-depth understanding of the characteristics of DCs would have a beneficial effect in overcoming the obstacle occurring in sepsis. This paper focuses on the role of DCs in the progression of sepsis and we also discuss the reverse sepsis-induced immunosuppression through manipulating the DC function. In addition, we highlight some potent immunotherapies that could be used as a novel strategy in the early treatment of sepsis.

scholarly journals Bifunctional Role of Protein Tyrosine Kinases in Late Preconditioning Against Myocardial Stunning in Conscious Rabbits

1999 ◽  
Vol 85 (12) ◽  
pp. 1154-1163 ◽  
Author(s):  
Buddhadeb Dawn ◽  
Yu-Ting Xuan ◽  
Yumin Qiu ◽  
Hitoshi Takano ◽  
Xian-Liang Tang ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Myocardial Stunning ◽  
Protein Tyrosine Kinases ◽  
Protein Tyrosine ◽  
Late Preconditioning ◽  
Conscious Rabbits
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