Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.10.2 (focal adhesion kinase)
44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In addition to a role in response to insulin and insulin-like growth factors, insulin receptor substrate 1 (IRS-1) is phosphorylated in response to IL-4, the interferons (IFNs) and oncostatin M (OSM). Here mutant cell lines lacking JAK1, JAK2, or Tyk2 were used to determine the role(s) of the Janus kinase (JAK) family of protein-tyrosine kinases in IRS-1 phophorylation. 32D cells, which do not express IRS proteins, were analyzed for any requirement for these proteins in response to the IFNs. For the mutant human fibrosarcoma cell lines, phosphorylation of IRS-1 through the insulin-like growth factor receptor is independent of JAK1, JAK2, or Tyk2. In contrast, phosphorylation of IRS-1 mediated by the Type I IFNs, IL-4, and OSM is JAK-dependent. For the alphabeta-IFNs, activation of IRS-1 is dependent on JAK1 and Tyk2, consistent with the interdependence of these kinases in the IFN-alphabeta response. Neither IRS-1 nor IRS-2 was detectably activated by IFN-gamma. Consistent with this, activation of neither IRS proteins appears to be an absolute requirement for an antiproliferative or an antiviral response to the IFNs. For IL-4 and OSM phosphorylation of IRS-1 in the human fibrosarcoma cells is largely dependent on JAK1 but can also be mediated through Tyk2 or JAK2. Activation of phosphatidylinositol 3'-kinase in response to IL-4 and OSM, at least, was also JAK-dependent. The JAKs are, therefore, required not only for STAT activation but also for the activation, through a variety of different types of cytokine receptor, of an additional signaling pathway(s) through IRS-1 and phosphatidylinositol 3'-kinase.
...
PMID:Janus kinase-dependent activation of insulin receptor substrate 1 in response to interleukin-4, oncostatin M, and the interferons. 930 69

Mutations of the Janus family kinase JAK3 have been found to be responsible for autosomal recessive severe combined immunodeficiency (SCID) in humans. We report here the analysis of four new unrelated patients affected by JAK3-deficient SCID. The genetic defects were heterogeneous and included a large intragenic deletion as well as different point mutations, leading to missense substitutions, early stop codons, or splicing defects. We performed a series of studies of the biochemical events induced by cytokines on lymphoblastoid B-cell lines obtained from these patients. Abnormalities in tyrosine phosphorylation of JAK3 in response to interleukin-2 (IL-2) and IL-4 were present in all patients. Accordingly, IL-2-mediated phosphorylation of STAT5 was also absent or barely detectable. On the contrary, in all cases, we could show reduced but clear phosphorylation of STAT6 upon IL-4 stimulation. In one patient carrying a single amino acid change (Glu481Gly) in the JH3 domain of JAK3, we observed partially conserved IL-2 responses resulting in reduced but detectable levels of JAK3 and STAT5 phosphorylation. Interestingly, the patient bearing this mutation developed a substantial number of circulating CD4(+)/CD45RO+ activated T lymphocytes that were functionally impaired. In two cases, patients' cells expressed JAK3 proteins with mutations in the JH2 pseudo-kinase domain. A single cysteine to arginine substitution (Cys759Arg) in this region resulted in high basal levels of constitutive JAK3 tyrosine phosphorylation unresponsive to either downregulation by serum starvation or cytokine-mediated upregulation. The characterization of the genetic defects and biochemical abnormalities in these JAK3-deficient patients will help define the role of JAK3 in the ontogeny of a competent immune system and may lead to a better understanding of the JAK3 functional domains.
...
PMID:Structural and functional basis for JAK3-deficient severe combined immunodeficiency. 935 68

The present study describes two novel cell lines, DUNATIS and SILVANUS, established from B lineage acute lymphoblastic leukemia patients. Respectively, DUNATIS and SILVANUS display an early pre-B cell and a pre-B cell phenotype. Spontaneous DNA replication of both cell lines was strongly inhibited by IL-4. This effect was directly mediated by IL-4 and exerted through the CD124 IL-4 receptor chain. Notably, IL-4 was associated with rapid cell death and reduction of cellularity in DUNATIS, whereas these parameters were considerably less pronounced and only observed after longer-term exposure of the SILVANUS cells to IL-4. In addition to these differences, although both cell lines expressed FES oncoprotein, a 100 kDa protein associated with FES was strikingly found to be tyrosine-phosphorylated in response to IL-4 exclusively in DUNATIS cells. These data demonstrate that IL-4 displays heterogenous effects on leukemic B cell precursors responsive to inhibition of DNA synthesis via IL-4 mediated engagement of the CD124 receptor chain. The present findings may be of use for appreciation of the effects of IL-4 in B lineage ALL, and the novel cell lines could represent a model for further identification of target molecules in IL-4 signalling.
...
PMID:Heterogeneity of the inhibitory effects of IL-4 in two novel B lineage acute lymphoblastic leukemia cell lines. 944 37

Leflunomide is an immunosuppressive drug capable of inhibiting T and B cell responses in vivo. A number of studies demonstrate that leflunomide functions both as a pyrimidine synthesis inhibitor and as a tyrosine kinase inhibitor. We previously reported that leflunomide inhibits LPS-stimulated B cell proliferation, cell cycle progression, and IgM secretion. This inhibition can be reversed by the addition of exogenous uridine, suggesting that leflunomide functions as a pyrimidine synthesis inhibitor in B cells. We report here that while the addition of uridine restored proliferation and IgM secretion to leflunomide-treated LPS-stimulated B cells, as determined by metabolic labeling and immunoprecipitation, it did not completely restore secretion of IgG Ab. We hypothesized that leflunomide inhibits LPS-induced IgG secretion by inhibiting tyrosine kinase activity required for isotype switch. We tested this hypothesis in a well-defined model of isotype switch, LPS plus IL-4 induction of IgG1. Leflunomide inhibited IgG1 secretion in this model in a dose-dependent manner. The signal transduction pathway utilized by IL-4 to induce IgG1 involves tyrosine phosphorylation of the IL-4 receptor, JAK1, JAK3, and STAT6 proteins induced by IL-4 binding to the IL-4R. Leflunomide diminished the tyrosine phosphorylation of JAK3 and STAT6 in the absence or presence of uridine. In gel mobility shift studies, STAT6 binding to the STAT6 DNA binding site in the IgG1 promoter decreased in the presence of leflunomide or leflunomide plus uridine. Taken together, these data suggest that leflunomide acts as a tyrosine kinase inhibitor to block IgG1 production.
...
PMID:Inhibition of JAK3 and STAT6 tyrosine phosphorylation by the immunosuppressive drug leflunomide leads to a block in IgG1 production. 946 13

In hematopoietic cells, interleukin-2 receptor (IL-2R) gamma chain (termed gammac) is shown to be a component of the IL-4R system, whereas in nonhematopoietic cells, gammac is absent and it is not a component of the IL-4R system. Here, we show that the IL-13R alpha' chain (termed IL-13Ralpha') but not the IL-13R alpha chain (termed IL-13Ralpha) can substitute for gammac and, thus, IL-13Ralpha' forms a novel component of the IL-4R system. This conclusion was drawn on the basis of chemical cross-linking, immunoprecipitation, the ability of IL-13Ralpha' but not IL-13Ralpha to augment IL-4 binding affinity, and the requirement of IL-13Ralpha' for IL-4-induced STAT6 activation in Chinese hamster ovary (CHO) cells transfected with various receptor subunits. Cotransfection of IL-4 receptor p140 (termed IL-4Rbeta) with gammac or IL-13Ralpha' increased IL-4 binding affinity and allowed for STAT6 activation in response to IL-4. However, cotransfection of all three chains did not further increase IL-4 binding or alter the extent of STAT6 activation suggesting that all three chains together do not seem to participate in IL-4 function. Instead, IL-4Rbeta heterodimerizes with gammac or IL-13Ralpha' and mediates STAT6 activation. Cotransfection of IL-4Rbeta with IL-13Ralpha neither increased IL-4 binding affinity nor allowed for STAT6 activation in response to IL-4 indicating that IL-13Ralpha does not convert binding affinity nor transmit signals for IL-4. Because IL-4 phosphorylates JAK1 and JAK2 tyrosine kinases in nonhematopoietic cells, we investigated whether JAK1 and JAK2 are required for IL-4-induced STAT6 activation in various transfectants. Cotransfection experiments with different chains of IL-4R and kinase-deficient JAK1 and JAK2 mutants in CHO cells showed that JAK1 and JAK2 are required for optimal activation of STAT6 in the alpha' beta transfectant but only partially in the beta gammac transfectant. Taken together, our results show that IL-13Ralpha' is a novel functional component of the IL-4R system and that JAK1 and JAK2 mediate IL-4-induced optimal activation of STAT6 in nonhematopoietic cells.
...
PMID:Interleukin-13 receptor alpha' but not alpha chain: a functional component of interleukin-4 receptors. 957 26

The phosphatidylinositol 3-kinase (PI3K)-signaling pathway has emerged as an important component of cytokine-mediated survival of hemopoietic cells. Recently, the protein kinase PKB/akt (referred to here as PKB) has been identified as a downstream target of PI3K necessary for survival. PKB has also been implicated in the phosphorylation of Bad, potentially linking the survival effects of cytokines with the Bcl-2 family. We have shown that granulocyte/macrophage colony-stimulating factor (GM-CSF) maintains survival in the absence of PI3K activity, and we now show that when PKB activation is also completely blocked, GM-CSF is still able to stimulate phosphorylation of Bad. Interleukin 3 (IL-3), on the other hand, requires PI3K for survival, and blocking PI3K partially inhibited Bad phosphorylation. IL-4, unique among the cytokines in that it lacks the ability to activate the p21ras-mitogen-activated protein kinase (MAPK) cascade, was found to activate PKB and promote cell survival, but it did not stimulate Bad phosphorylation. Finally, although our data suggest that the MAPK pathway is not required for inhibition of apoptosis, we provide evidence that phosphorylation of Bad may be occurring via a MAPK/ERK kinase (MEK)-dependent pathway. Together, these results demonstrate that although PI3K may contribute to phosphorylation of Bad in some instances, there is at least one other PI3K-independent pathway involved, possibly via activation of MEK. Our data also suggest that although phosphorylation of Bad may be one means by which cytokines can inhibit apoptosis, it may be neither sufficient nor necessary for the survival effect.
...
PMID:Dissociation of cytokine-induced phosphorylation of Bad and activation of PKB/akt: involvement of MEK upstream of Bad phosphorylation. 963 68

IL-13, a cytokine similar to IL-4, is a regulator of human B cell and monocyte functions. Biologic effects of IL-13 on primary human NK and T cells have not been well defined. We demonstrate that, in primary NK cells, IL-13, but not IL-4, may induce low levels of IFN-gamma secretion. When NK cells were costimulated with IL-13 and IL-2, IL-13 generally resulted in two types of reactivity: IL-13 synergized with IL-2 to stimulate IFN-gamma production or it modestly inhibited IL-2-mediated IFN-gamma production. In both types of donors, the effect of IL-13 on IL-2-induced IFN-gamma production was in marked contrast to the strong inhibition seen with IL-4 in NK cells. Additionally, IL-13 suppresses IL-2-induced NK cytolytic and proliferative activities although less efficiently than IL-4. In T cells, IL-13 inhibits anti-CD3 mAb/IL-2- or PHA-mediated IFN-gamma production and enhances cytolytic potential. Furthermore, we demonstrate that IL-13, like IL-4, induces distinct STAT6-DNA binding complexes and tyrosine phosphorylation of STAT6 and Janus kinase 3 (JAK3) in NK and T cells. We observed that Abs directed against unique domains of STAT6 have differential effects on complexes in T cells but not in NK cells, suggesting different STAT6 isoforms. These findings show that IL-13 and IL-4 have the ability to regulate NK and T cell activation and that IL-13 is a potent regulator of STAT6 and JAK3 in these cell types.
...
PMID:Differential regulation of the Janus kinase-STAT pathway and biologic function of IL-13 in primary human NK and T cells: a comparative study with IL-4. 964 27

Eosinophils, along with mast cells are key cells involved in the innate immune response against parasitic infection whereas the adaptive immune response is largely dependent on lymphocytes. In chronic parasitic disease and in chronic allergic disease, IL-5 is predominantly a T cell derived cytokine which is particularly important for the terminal differentiation, activation and survival of committed eosinophil precursors. The human IL-5 gene is located on chromosome 5 in a gene cluster that contains the evolutionary related IL-4 family of cytokine genes. The human IL-5 receptor complex is a heterodimer consisting of a unique alpha subunit (predominantly expressed on eosinophils) and a beta subunit which is shared between the receptors for IL-3 & GM-CSF (more widely expressed). The alpha subunit is required for ligand-specific binding whereas association with the beta subunit results in increased binding affinity. The alternative splicing of the alpha IL-5R gene which contains 14 exons can yield several alpha-IL-5R isoforms including a membrane-anchored isoform (alpha IL-5Rm) and a soluble isoform (alpha IL-5Rs). Cytokines such as IL-5 produce specific and non-specific cellular responses through specific cell membrane receptor mediated activation of intracellular signal transduction pathways which, to a large part, regulate gene expression. The major intracellular signal transduction mechanism is activation of non-receptor associated tyrosine kinases including JAK and MAP kinases which can then transduce signals via a novel family of transcriptional factors named signal transducers and activators of transcription (STATS). JAK2, STAT1, and STAT5 appear to be particularly important in IL-5 mediated eosinophil responses. Asthma is characterized by episodic airways obstruction, increased bronchial responsiveness, and airway inflammation. Several studies have shown an association between the number of activated T cells and eosinophils in the airways and abnormalities in FEV1, airway reactivity and clinical severity in asthma. It has now been well documented that IL-5 is highly expressed in the bronchial mucosa of atopic and intrinsic asthmatics and that the increased IL-5 mRNA present in airway tissues is predominantly T cell derived. Immunocytochemical staining of bronchial biopsy sections has confirmed that IL-5 mRNA transcripts are translated into protein in asthmatic subjects. Furthermore, the number of activated CD4 + T cells and IL-5 mRNA positive cells are increased in asthmatic airways following antigen challenge and studies that have examined IL-5 expression in asthmatic subjects before and after steroids have shown significantly decreased expression following oral corticosteroid treatment in steroid-sensitive asthma but not in steroid resistant and chronic severe steroid dependent asthma. The link between T cell derived IL-5 and eosinophil activation in asthmatic airways is further strengthened by the demonstration that there is an increased number of alpha IL-5R mRNA positive cells in the bronchial biopsies of atopic and non-atopic asthmatic subjects and that the eosinophil is the predominant site of this increased alpha IL-5R mRNA expression. We have also shown that the subset of activated eosinophils that expressed mRNA for membrane bound alpha IL-5r inversely correlated with FEV1, whereas the subset of activated eosinophils that expressed mRNA for soluble alpha IL-5r directly correlated with FEV1. Hence, not only does this data suggest that the presence of eosinophils expressing alpha IL-5R mRNA contribute towards the pathogenesis of bronchial asthma, but also that the eosinophil phenotype with respect to alpha IL-5R isoform expression is of central importance. Finally, there are several animal, and more recently in vitro lung explant, models of allergen induced eosinophilia, late airway responses (LARS), and bronchial hyperresponsiveness (BHR)--all of which support a link between IL-5 and airway eosinophilia and bronc
...
PMID:IL-5 and IL-5 receptor in asthma. 969 19

IL-13 and IL-4, pleiotropic immune regulatory cytokines, have been shown to mediate similar prominent effects in human fibroblast cell lines. However, molecular mechanisms for their redundant effects are not known. Here, we have investigated the structure of IL-13 receptors (IL-13R) and molecular mechanisms of signal transduction through IL-13 and IL-4 receptors in non-transformed normal skin fibroblast cell lines. We demonstrate that high-affinity IL-13R is expressed in normal skin fibroblast cell lines. Upon [125I]1L-13 cross-linking, a approximately 60-70 kDa band was observed in sk559 and sk574 fibroblast cell lines. By RT-PCR analysis, mRNA for IL-13R alpha, IL-13R alpha' and IL-4Rbeta chains were expressed; however, the IL-2Rgamma chain, shown to participate and modulate IL-4 and IL-13 binding, was not expressed in any of the cell lines examined. The Janus kinase (JAK)2 and Tyk2 were phosphorylated in response to IL-4 or IL-13 in sk559 and sk574 cell lines. JAK1 was also phosphorylated in one of two cell lines while JAK3 was present but not phosphorylated in any of the cell lines studied. A signal transduction and activator of transcription (STAT)6 was also activated in response to both IL. An insulin receptor substrate (IRS)-1 was constitutively phosphorylated and its phosphorylation level was augmented in response to both IL. These results suggest that the mechanism of signal transduction through IL-13 and IL-4 receptors in human fibroblast cell lines is similar, and this may, at least in part, be responsible for the redundant effects of these two cytokines. In addition, JAK2 tyrosine kinase instead of JAK3 appears to play a major role in IL-4- and IL-13-induced signal transduction in human fibroblasts.
...
PMID:Two different IL-13 receptor chains are expressed in normal human skin fibroblasts, and IL-4 and IL-13 mediate signal transduction through a common pathway. 972 96

The tight-skin (Tsk/+) mutant mouse, a putative murine model of scleroderma, is characterized primarily by the excessive deposition of collagen and other extracellular matrix molecules in the dermis, and also by a developmentally acquired defect in pulmonary architecture. Passive transfer experiments have suggested an etiologic role for the immune system in Tsk/+ dermal pathology. In addition, CD4+ T lymphocytes have been shown to be required for the excessive accumulation of dermal collagen in these mice. As IL-4, a product of differentiated CD4+ T cells, is capable of regulating the synthesis of various matrix molecules (including type I collagen) by fibroblasts in vitro, we investigated the potential role of IL-4 in mediating Tsk/+ dermal fibrosis. Confirming that Tsk/+ cells are capable of responding to IL-4, we found receptors for this cytokine on Tsk/+ embryonic fibroblasts and a dermal fibroblast cell line derived from these mice. Furthermore, IL-4 receptors on Tsk/+ fibroblasts were functional since IL-4 stimulation in vitro increased type I collagen secretion from these cells. These results demonstrated the potential for IL-4 to be directly involved in the excessive deposition of dermal collagen in Tsk/+ mice. Critical insight into the role played by IL-4 in mediating the dermal phenotype, however, was obtained following the administration of neutralizing anti-lL-4 antibodies to Tsk/+ mice. This treatment prevented the development of dermal fibrosis, leading to normalization of dermal collagen content. Given the requirement for CD4+ T cells in Tsk/+ dermal fibrosis, our results suggest that Th2 cells and/or factors elaborated by this T cell subset may play a key role in regulating dermal collagen content in this strain.
...
PMID:Anti-IL-4 treatment prevents dermal collagen deposition in the tight-skin mouse model of scleroderma. 975 50


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---