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

Overexpression of rat recombinant calcineurin A catalytic subunit in E. coli was achieved using a system under control of the T7 promoter. The specific activity of the purified catalytic subunit was suppressed relative to native bovine calcineurin, with the extent of suppression depending upon the choice of substrate. Addition of calcineurin B subunit stimulated phosphatase activity to one third that of native calcineurin. The metal activators Mn2+ and Ni2+ as well as several anion inhibitors affected both native calcineurin and recombinant calcineurin A activity to the same extent. In addition, calcineurin B was required for inhibition by the immunosuppressive complex FK506-FK506-binding protein.
...
PMID:Overexpression and characterization of a recombinant form of rat calcineurin A. 751 97

The specificity of cyclosporin A (CsA) binding to the major intracellular receptor proteins, cyclophilin A and B, as well as the interaction of CsA with the phosphatase calcineurin were investigated. Binding of photoaffinity-labeled CsA (PL-CS), a photoaffinity probe of CsA, to recombinant human cyclophilin A and B is saturable and specific. Non-specific PL-CS binding to calcineurin is observed in the absence of cyclophilin and calmodulin. In the presence of cyclophilin, cyclosporin-calcineurin binding becomes specific. Ternary complexes containing an equimolar ratio of cyclophilin A or B, PL-CS and calcineurin are resolved using the chemical-crosslinking technique. The formation of these complexes is specific, calcium- but not calmodulin-dependent, and is only inhibitable by cyclosporins, which bind cyclophilin. The drug-immunophilin complex binds to the calcineurin A subunit. The proteolytic 43 kDa product of calcineurin A retains binding properties, suggesting that the C-terminal domains are not necessary for complex formation. A trimeric complex of FKBP-calcineurin is also formed with FK506, but not with rapamycin. As expected, these complexes are only competed with by homologous derivatives. Chemical crosslinking of photolabeled Jurkat T-cells strongly suggests that drug-calcineurin complexes are of biological relevance.
...
PMID:Demonstration of ternary immunophilin-calcineurin complexes with the immunosuppressants cyclosporin and macrolide FK506. 751 9

The interaction of the immunosuppressive complexes cyclosporin A-cyclophilin A and FK506 binding protein-FK506 with the Ca(2+)- and calmodulin-dependent protein phosphatase calcineurin has been investigated by means of photoaffinity labeling and chemical cross-linking. Photolabeling of purified bovine brain calcineurin with the affinity label [O-[4-[4-(1-diazo-2,2,2-trifluoroethyl)benzoyl]aminobutanoyl]-D- serine8]cyclosporin in the presence of cyclophilin A results, in addition to the labeling of cyclophilin itself, in the transfer of some of the chemical probe to both the catalytic subunit A and the regulatory subunit B of calcineurin. Chemical cross-linking studies with disuccinimidyl suberate in the presence of either cyclophilin A, B, or C in complex with cyclosporin A or FK506 binding protein-FK506 result on the other hand in the apparently exclusive and strictly immunosuppressant-dependent formation of covalent immunophilin-calcineurin B subunit products. Cross-linking of immunophilins to calcineurin B subunit requires the presence of subunit A. In the present study, using a set of recombinant maltose-binding protein fusion products representing different stretches of the catalytic subunit A, we were able to map the minimal calcineurin A sequence necessary for immunophilin-ligand-calcineurin B interaction to occur.
...
PMID:Mapping of the immunophilin-immunosuppressant site of interaction on calcineurin. 751 2

The immunosuppressant cyclosporin A (CsA) was utilized as a highly specific inhibitor of the Ca2+/calmodulin-dependent protein phosphatase, PP2B in rat pancreatic acinar cells. Treatment of cells with CsA for 20 min resulted in a concentration-dependent inhibition of PP2B that was maximal (> 90%) at 1 microM and exhibited an IC50 of 65 nM. CsA also inhibited cholecystokinin-, 100 pM, or carbamylcholine-, 10 microM, induced amylase release in a concentration-dependent manner. A maximal inhibition to 55% of stimulated control cells occurred at 1 microM CsA with half-maximal inhibition occurring at approximately 200 nM. Secretion in response to 1 microM 12-O-tetradecanoylphorbol-13-acetate (TPA) was uneffected by CsA treatment. Conversely, amylase release stimulated by the Ca2+ mobilizing agent, thapsigargin, when added alone at 2 microM or in combination with TPA, was inhibited by CsA to 66 and 61% of control cells, respectively. These data indicate that CsA-mediated inhibition occurs only when stimulation involves an increase in intracellular Ca2+. In addition, analogues of CsA, 6-methyl-alanine-CsA, and 11-methyl-leucine-CsA had no effect on PP2B activity or amylase secretion. The chemically distinct immunosuppressant, FK506, produced only partial inhibition of PP2B activity and did not significantly inhibit amylase secretion at concentrations up to 1 microM. Two-dimensional gel electrophoresis of proteins from 32P-labeled acinar cells revealed that CsA specifically blocked the cholecystokinin-stimulated dephosphorylation of a 24-kDa protein in a concentration range similar to that seen for inhibition of secretion. Using 32P-labeled cytosol and purified calcineurin, a Ca(2+)- and calmodulin-dependent dephosphorylation of the 24-kDa protein was also demonstrated in vitro. Collectively, these data indicate that the Ca2+/calmodulin-dependent protein phosphatase, PP2B, plays a significant role in stimulus-secretion coupling in pancreatic acinar cells.
...
PMID:Cyclosporin A inhibits Ca2+/calmodulin-dependent protein phosphatase and secretion in pancreatic acinar cells. 751 49

The immunophilin-immunosuppressant complexes cyclophilin-cyclosporin A (CsA) and FKBP12-FK506 inhibit the phosphatase calcineurin to block T-cell activation. Although cyclophilin A, FKBP12, and calcineurin are highly conserved from yeast to man, none had previously been shown to be essential for viability. We find that CsA-sensitive yeast strains are FK506 hypersensitive and demonstrate that calcineurin is required for viability in these strains. Mutants lacking cyclophilin A or FKBP12 are resistant to CsA or FK506, respectively. Thus, both the immunosuppressive and the antifungal actions of CsA and FK506 result from calcineurin inhibition by immunophilin-drug complexes. In yeast strains in which calcineurin is not essential, calcineurin inhibition or mutation of calcineurin confers hypersensitivity to LiCl or NaCl, suggesting that calcineurin regulates cation transport.
...
PMID:Calcineurin is essential in cyclosporin A- and FK506-sensitive yeast strains. 751

Whole-cell recordings were made from dorsomedial nucleus tractus solitarii neurons in thin coronal medullary slices of the rat, at the level of the area postrema. Monosynaptic excitatory postsynaptic currents (EPSCs) were evoked in the tractus solitarius by electrical stimulation in the presence of D-2-amino-5-phosphonopentanoic acid (AP5) and bicuculline. Currents were also evoked by pressure ejection of (S)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) in the presence of AP5, bicuculline, and tetrodotoxin or muscimol in the presence of 6,7-dinitroquinoxaline-2,3-dione and AP5. The metabotropic glutamate receptor (mGluR) agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylate [(1S,3R)-ACPD] reversibly depressed the EPSC and muscimol currents and reversibly potentiated AMPA currents. The effects of (1S,3R)-ACPD were blocked in the presence of a low concentration of the phosphoprotein phosphatase (PP)1 and PP2A inhibitor okadaic acid (OA) but not by a low concentration of the PP inhibitor calyculin A. The immunosuppressant agent FK506 failed to block (1S,3R)-ACPD effects on AMPA currents. However, (1S,3R)-ACPD applied in the presence of FK506 produced a reversible potentiation of muscimol currents. We previously demonstrated that the cell-permeant cGMP analog 8-Br-cGMP can mimic many of the effects of (1S,3R)-ACPD. OA antagonized the effects of 8-Br-cGMP in the present investigation. Finally, we previously demonstrated that brief tetanic stimulation results in the activation of a presynaptic mGluR autoreceptor and depression of subsequently evoked EPSCs. OA similarly blocked tetanus-induced depression of EPSCs. These findings suggest that mGluRs on tractus solitarius afferents and first-order nucleus tractus solitarii neurons may modulate glutamate release and AMPA and gamma-aminobutyric acid type A receptor activity via activation of one or more PPs, such as PP2A and/or calcineurin.
...
PMID:Inhibition of phosphoprotein phosphatases blocks metabotropic glutamate receptor effects in the rat nucleus tractus solitarii. 751 97

The immunosuppressants rapamycin and FK506 bind to the same intracellular protein, the immunophilin FKBP12. The FKB12-FK506 complex interacts with and inhibits the Ca(2+)-activated protein phosphatase calcineurin. The target of the FKBP12-rapamycin complex has not yet been identified. We report that a protein complex containing 245 kDa and 35 kDa components, designated rapamycin and FKBP12 targets 1 and 2 (RAFT1 and RAFT2), interacts with FKBP12 in a rapamycin-dependent manner. Sequences (330 amino acids total) of tryptic peptides derived from the 245 kDa RAFT1 reveal striking homologies to the yeast TOR gene products, which were originally identified by mutations that confer rapamycin resistance in yeast. A RAFT1 cDNA was obtained and found to encode a 289 kDa protein (2549 amino acids) that is 43% and 39% identical to TOR2 and TOR1, respectively. We propose that RAFT1 is the direct target of FKBP12-rapamycin and a mammalian homolog of the TOR proteins.
...
PMID:RAFT1: a mammalian protein that binds to FKBP12 in a rapamycin-dependent fashion and is homologous to yeast TORs. 751 56

Tacrolimus(FK506) is a strong immuno-suppressant and shows its activity through inhibiting IL-2 mRNA transcription by forming pentameric complex with intracellular receptor(FK506 binding protein 12 kDa or FKBP12), Ca2+, calmodulin, and calcineurin. Here, we report the binding activity to FKBP12, the pentameric complex formation and Con-A response inhibiting activities of 7 metabolites. C15-demethylated metabolite(M-3) needed higher quantity to compete in Con-A assay and in pentamer formation assay, although it binds more strongly to FKBP12. The result suggests that the ability to form a pentameric complex is not a two step reaction with the first binding to FKBP12, but a single step reaction by components for the pentamer formation.
...
PMID:Interaction of tacrolimus(FK506) and its metabolites with FKBP and calcineurin. 751 78

Transcription of the human tumor necrosis factor alpha (TNF-alpha) gene is one of the earliest events that occurs after stimulation of B or T cells via their antigen receptors. Antibody directed at surface immunoglobulin (anti-Ig) on B cells has previously been shown to induce a rapid burst of TNF-alpha gene transcription, which can be blocked by the immunosuppressants cyclosporin A (CsA) and FK506. Here, TNF-alpha gene transcription is shown also to be highly and rapidly induced in human B cells after stimulation via the CD40 and interleukin 4 pathways, which similarly is inhibited by CsA and a panel of CsA or FK506 analogues that block calcineurin phosphatase activity. Endogenous TNF-alpha produced after stimulation was involved in B-cell proliferation since anti-TNF-alpha monoclonal antibody inhibited both anti-Ig- and anti-CD40-induced B-cell proliferative responses. Moreover, addition of TNF-alpha during stimulation resulted in augmentation of B-cell proliferation, which was also inhibited by anti-TNF-alpha monoclonal antibody. Although lymphotoxin alpha (LT-alpha) mRNA is induced by both pathways, it is not blocked by CsA, whereas LT-beta mRNA is constitutively expressed in B cells. Thus, TNF-alpha is a necessary autocrine growth factor for human B cells stimulated via two independent CsA-sensitive pathways and plays a role similar to that of interleukin 2 in T-cell proliferation. The autocrine nature of TNF-alpha in activated B cells implies a potential role for this cytokine in infection-related polyclonal B-cell expansion and in B-cell malignancies.
...
PMID:Tumor necrosis factor alpha is an autocrine growth factor for normal human B cells. 751 25

A role of Ca2+/calmodulin-dependent protein phosphatase (calcineurin) in induction of long-term potentiation (LTP) was investigated using its selective inhibitor, FK506, in visual cortical slices of young rats. Field potentials or excitatory postsynaptic potentials (EPSPs) to test stimulation of white matter were recorded extra- or intracellularly from layer 2/3, and tetanic stimulation (tetanus) was applied to the white matter at 5 Hz. During the application of FK506 (1 microM), short tetanus (6 s) which had rarely induced LTP in the normal medium, became effective in inducing LTP. Tetanus for 1 min in the presence of FK506 induced LTP with higher probability than in the normal medium. To test possible involvement of presynaptic mechanisms, paired pulses at 50 ms intervals were given to the white matter. The facilitation ratio of the second to first EPSPs was not significantly changed by FK506 and after the induction of LTP, suggesting that the action of FK506 may not be presynaptic. To confirm this, FK506 was injected directly into neurons through recording electrodes. In cases in which stable EPSPs were recorded, the probability of LTP induction became higher than that obtained with normal electrodes. These results suggest that calcineurin plays a role in processes antagonizing the induction of LTP in visual cortex.
...
PMID:Effects of an inhibitor for calcium/calmodulin-dependent protein phosphatase, calcineurin, on induction of long-term potentiation in rat visual cortex. 752 Jan 43


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

---