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

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Query: EC:3.1.3.16 (calcineurin)
17,112 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

IL-17 (IL-17A or CTLA-8) is the founding member of a novel family of inflammatory cytokines, and emerging evidence indicates that it plays a central role in inflammation and autoimmunity. IL-17 is made primarily, if not exclusively by T cells, but relatively little is known about how its expression is regulated. In the present study, we examined the requirements and mechanisms for IL-17 expression in primary mouse lymphocytes. Like many cytokines, IL-17 is induced rapidly in primary T cells after stimulation of the T cell receptor (TCR) through CD3 crossinking. Surprisingly, however, the pattern of regulation of IL-17 is different in mice than in humans, because "costimulation" of T cells through CD28 only mildly enhanced IL-17 expression, whereas levels of IL-2 were dramatically enhanced. Similarly, several other costimulatory molecules such as ICOS, 4-1BB and CD40L exerted only very weak enhancing effects on IL-17 production. In agreement with other reports, IL-23 enhanced CD3-induced IL-17 expression. However, IL-17 production can occur autonomously in T cells, as neither dendritic cells nor IL-23 were necessary for promoting short-term production of IL-17. Finally, to begin to characterize the TCR-mediated signaling pathway(s) required for IL-17 production, we showed that IL-17 expression is sensitive to cyclosporin-A and MAPK inhibitors, suggesting the involvement of the calcineurin/NFAT and MAPK signaling pathways.
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PMID:Signaling through the murine T cell receptor induces IL-17 production in the absence of costimulation, IL-23 or dendritic cells. 1640 47

Calcineurin antagonists are known as potent immunosuppressants working particularly on T cells by virtue of their capacity to block nuclear factor of activated T cell (NFAT) activation and translocation to the nucleus. In addition to interleukin (IL)-2 suppression, T helper cell type 1 (Th1) as well as Th2 cytokine transcription is blocked by calcineurin antagonists. Here, we show that calcineurin antagonists such as cyclosporin A (CsA) or tacrolimus can markedly enhance the production of interferon-gamma (IFN-gamma) by human T cells. This increased IFN-gamma production is dependent on T cell receptor (TCR) and CD28 signaling as well as on the presence of IL-12. IL-27, which could mimic the effect of IL-12, was however less potent in inducing IFN-gamma production in the presence of CsA and TCR stimulation. Other cytokines such as IL-23, IL-18, IL-2, or the Th2-related cytokine IL-4 are not able to support a calcineurin antagonist-dependent up-regulation of IFN-gamma. CsA-dependent IFN-gamma production is observable in therapeutic concentrations. The effect is independent of IL-10 or IL-4, as addition of these cytokines could not inhibit the CsA-induced IFN-gamma production. The effect of calcineurin antagonists is associated with an increased c-fos expression and DNA-binding activity of the transcription factor activated protein-1 but not with increased DNA-binding activity of T-bet. Our study further supports the relevance of known calcineurin activities other than NFAT activation. The presented data may help to explain why concomitant infections (resulting in increased IL-12 expression) under therapy with calcineurin antagonists often have a negative impact on the activity of the underlying disease (e.g., autoimmune disease).
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PMID:Critical involvement of IL-12 in IFN-gamma induction by calcineurin antagonists in activated human lymphocytes. 1664 Nov 33

The inducible costimulator (ICOS), a member of the CD28 family of costimulatory molecules, is rapidly induced upon T cell activation. Although the critical role of ICOS in costimulating T cell responses is well documented, little is known of the intracellular signaling pathways and mechanisms that regulate ICOS expression. Here, we report that Fyn, NFAT, and ERK signaling influence ICOS expression as various chemical inhibitors, such as PP2 that targets Src kinases, U0126 that targets MEK1/2, and cyclosporin A or FK506 that targets calcineurin and thereby affects NFAT, attenuate T cell receptor-mediated ICOS induction. Moreover, ectopic expression of NFATc2 or a constitutively active MEK2 amplifies ICOS transcription and transactivates a 288-bp core region of the icos promoter in luciferase reporter assays. We also identify a site on the icos promoter that is sensitive to ERK signaling and further show that NFATc2 can bind the icos promoter in vivo and that this binding is diminished when Fyn signaling is ablated. The normal activation of ERK but reduced nuclear translocation of NFATc2 in Fyn(-/-) CD4(+) T cells further suggest that Fyn and NFATc2 act in a common axis, separate from that involving ERK, to drive ICOS transcription. Taken together, our findings indicate that Fyn-calcineurin-NFATc2 and MEK2-ERK1/2 are two independent signaling pathways that cooperate to control T cell receptor-mediated ICOS induction.
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PMID:Regulation of mouse inducible costimulator (ICOS) expression by Fyn-NFATc2 and ERK signaling in T cells. 1688 Feb 6

Costimulation of T cells via CD28 promotes both proliferation and resistance to apoptosis. In this study, we show that the immunosuppressive drug cyclosporin A (CsA) fully reverses resistance to CD95-mediated cell death after TCR/CD28 costimulation or superagonistic anti-CD28 mAb stimulation of primary rat lymph node T cells. This effect correlated with a pronounced superinduction of caspase-3 on both mRNA and protein levels, whereas its main antagonist, X chromosome-linked inhibitor of apoptosis, was unaffected by inclusion of CsA. Apoptosis triggered by CD95 cross-linking was characterized by robust caspase-3 activation. Furthermore, CsA sensitization to CD95-mediated apoptosis of CD28-activated T cells did not alter mRNA stability of superinduced caspase-3 mRNA, suggesting a transcriptional regulation of the caspase-3 gene. Addition of Ca(2+) ionophores to TCR/CD28 or superagonistic CD28-stimulated cells reduced caspase-3 levels, further supporting a role for Ca(2+)-dependent signaling pathways in negatively regulating caspase-3. Taken together, these findings suggest that CsA promotes sensitivity to CD95-mediated apoptosis in CD28-stimulated T cells by superinduction of the caspase-3 gene via a mechanism involving suppression of the calcineurin pathway.
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PMID:Cyclosporin A abolishes CD28-mediated resistance to CD95-induced apoptosis via superinduction of caspase-3. 1711 39

TCR signals induce the nuclear localization of NFATc proteins, which are removed from the nucleus after rephosphorylation by glycogen synthase kinase 3 and other kinases. Rapid nuclear export might allow continuous monitoring of receptor occupancy, making the transcriptional response proportional to the duration of TCR/CD28 signaling. To investigate this possibility, we analyzed mice in which T cells express a NFATc1 variant (NFATc1(nuc)) with serine-to-alanine changes at the glycogen synthase kinase 3 phosphorylation sites. NFATc1(nuc) T cells have constitutively nuclear NFATc1, enhanced T cell activation in vivo, and calcineurin-independent proliferation in vitro. NFATc1(nuc) T cells are hypersensitive to TCR/CD3 stimulation, resulting in enhanced proliferation and cytokine production that is independent of CD28 costimulation. These results support the notion that CD28 inhibits nuclear export of NFATc transcription factors. In addition, NFATc1(nuc) destabilizes a positive feedback loop in which NFATc1 activates its own transcription as well as its targets, such as CD40 ligand and Th1/Th2 cytokines.
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PMID:Enhanced NFATc1 nuclear occupancy causes T cell activation independent of CD28 costimulation. 1737 88

Kidney transplantation today has excellent short-term outcomes that have paralleled the use of new immunosuppressive agents introduced in the 1990s. In addition to reducing acute rejection, the goals for developing new agents is to improve long-term outcome, minimize nephrotoxicity, and reduce infectious, cardiovascular, and malignancy-related complications. Novel small molecules and biological agents currently in clinical development may help to minimize the use of calcineurin inhibitors and steroids. These small molecules include FTY720, a sphingosine phosphate-receptor modulator, FK778, an inhibitor of pyrimidine synthesis, CP-690550, a JAK3 inhibitor, and AEB-071, a protein kinase C inhibitor. The biological agents include drugs targeting interleukin-15, anti-CD40, belatacept (LEA29Y), a second-generation CTLY4Ig that blocks the interaction between CD80/86 and CD28 costimulatory pathways, and efalizumab, a humanized anti-LFA1 monoclonal antibody. These new agents currently in preclinical and clinical trials appear promising and may represent the emergence of novel immunosuppressive agents that can deliver immunosuppression without long-term toxicity.
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PMID:Novel immunosuppression: small molecules and biologics. 1761 78

Pimecrolimus is an ascomycin macrolactam derivative that has been recently approved for the topical treatment of atopic dermatitis. In this study we report for the first time on a direct comparison of the inhibitory activity of pimecrolimus and the glucocorticosteroids betamethasone 17-valerate, dexamethasone and hydrocortisone at the level of T-cell proliferation and cytokine production. Stimulated human peripheral blood mononuclear cell (PBMC) systems were used that are either sensitive or resistant to calcineurin inhibitors or glucocorticosteroids. Pimecrolimus and the glucocorticosteroids inhibited dose-dependently T-cell proliferation and cytokine production in a sensitive system (anti-CD3 mAb-stimulated PBMC) with the following rank order of potency: pimecrolimus approximately betamethasone 17-valerate approximately dexamethasone > hydrocortisone. In resistant systems (anti-CD3 plus anti-CD28- or Staphylococcal enterotoxin B-stimulated PBMC), pimecrolimus or the glucocorticosteroids alone exerted either no effect, or only a partial inhibitory effect. However, combinations of pimecrolimus with a glucocorticosteroid synergistically and strongly inhibited T-cell proliferation. Taken together, the data indicate that medium potency glucocorticosteroids, such as betamethasone 17-valerate and dexamethasone, are as potent T-cell inhibitors as pimecrolimus. Furthermore, the experimental evidence suggests that combinations of glucocorticosteroids and pimecrolimus could be used clinically to achieve superior therapeutic efficacy, when monotherapy with the individual agents is unsatisfactory.
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PMID:Inhibition of T-cell activation in vitro in human peripheral blood mononuclear cells by pimecrolimus and glucocorticosteroids and combinations thereof. 1762 98

T cell receptor (TCR) and costimulatory receptor (CD28) signals cooperate in activating T cells, although understanding of how these pathways are themselves regulated is incomplete. We found that Homer2 and Homer3, members of the Homer family of cytoplasmic scaffolding proteins, are negative regulators of T cell activation. This is achieved through binding of nuclear factor of activated T cells (NFAT) and by competing with calcineurin. Homer-NFAT binding was also antagonized by active serine-threonine kinase AKT, thereby enhancing TCR signaling via calcineurin-dependent dephosphorylation of NFAT. This corresponded with changes in cytokine expression and an increase in effector-memory T cell populations in Homer-deficient mice, which also developed autoimmune-like pathology. These results demonstrate a further means by which costimulatory signals are regulated to control self-reactivity.
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PMID:NFAT binding and regulation of T cell activation by the cytoplasmic scaffolding Homer proteins. 1821 1

Increased Ca(2+) influx is found in mononuclear cells (MNC) of patients with systemic lupus erythematosus (SLE). The role of calcineurin and potential implication of calcium channel blocker to suppress the abnormal Ca(2+) influx in SLE remain to be determined. In the present study, we found that the expression and phosphatase activity of calcineurin, but not calcineurin inhibitor in SLE-MNC were greater than normal MNC. Functionally, 1 microM nifedipine could suppress SLE-MNC IFN-gamma secretion but 10 microM nifedipine was required for suppressing that of normal MNC. IL-10 secretion by both SLE-MNC and normal MNC was suppressed by 1 microM nifedipine. However, high dose of nifedipine (50 microM) suppressed NFATc1 activation in SLE-MNC and enhanced apoptosis of anti-CD3 + anti-CD28-activated SLE-MNC irrelevant to expression of Fas ligand. These data suggest that SLE-MNC overexpressed calcineurin and hyper-responded to L-type Ca(2+) channel blocker-mediated apoptosis and cytokine suppression. We proposed that L-type Ca(2+) channel blocker maybe a potential medication for controlling SLE.
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PMID:Nifedipine suppresses Th1/Th2 cytokine production and increased apoptosis of anti-CD3 + anti-CD28-activated mononuclear cells from patients with systemic lupus erythematosus via calcineurin pathway. 1879 Jun 72

Junctional adhesion molecule (JAM)-C is an Ig superfamily protein, which is involved in the regulation of various inflammatory and vascular events such as transendothelial leukocyte migration. JAM-C is expressed highly on the surface of endothelial cells and platelets, whereas expression in T lymphocytes is not well studied. To investigate the specific gene regulation of JAM-C in T lymphocytes, we determined JAM-C expression in quiescent and activated human T cells. Treatment with the polyclonal T cell activator PHA increased surface and total JAM-C expression in T cells time- and dose-dependently, as determined by flow cytometry and immunoblot analysis. In contrast, no up-regulation of JAM-A in activated T cells was detectable. The highest level of JAM-C up-regulation by PHA was observed in CD3(+)forkhead box P3(+) and CD4(+)CD25(high) T cells. Moreover, TCR activation with combined anti-CD3 and anti-CD28 stimulation induced JAM-C expression in T cells. JAM-C induction occurred at the mRNA level, suggesting a transcriptional regulatory mechanism of JAM-C expression. Accordingly, we studied the regulation of the human JAM-C gene promoter in transiently transfected T cells. Luciferase activity of a JAM-C promoter gene construct with three potential consensus sites for the transcription factor NFAT was induced markedly in activated T cells. Finally, pretreatment with two pharmacological inhibitors of calcineurin, cyclosporin A, and FK-506, but not with MAPK inhibitors, blocked JAM-C induction in activated T cells. In summary, JAM-C is up-regulated in activated human T lymphocytes via a transcriptional mechanism, suggesting a potential role of JAM-C in T cell functions.
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PMID:Transcriptional induction of junctional adhesion molecule-C gene expression in activated T cells. 1920 48


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