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)

The immunophilin FKBP12 is one of the most abundant and conserved proteins in biology. It is the primary receptor for the immunosuppressant actions of the drug FK506 in whose presence FKBP12 binds to and inhibits calcineurin, disrupting interleukin formation in lymphocytes. The physiologic functions of FKBP12 are less clear, although the protein has been demonstrated to physiologically interact with the inositol 1,4,5-trisphosphate receptor (IP3R), the ryanodine receptor, and the type 1 transforming growth factor beta receptor. We now report that FKBP12 binds the IP3R at residues 1400-1401, a leucyl-prolyl dipeptide epitope that structurally resembles FK506. We further demonstrate that binding to IP3R at this site enables FKBP12 to interact with calcineurin, presumably to anchor the phosphatase to IP3R and modulate the receptor's phosphorylation status. We propose that FK506 promotes an FKBP12-calcineurin interaction by mimicking structurally similar dipeptide epitopes present within proteins that use FKBP12 to anchor calcineurin to the appropriate physiologic substrates.
...
PMID:FKBP12 binds the inositol 1,4,5-trisphosphate receptor at leucine-proline (1400-1401) and anchors calcineurin to this FK506-like domain. 934 94

The immunophilins are a family of proteins that are receptors for immunosuppressant drugs, such as cyclosporin A, FK506, and rapamycin. They occur in two classes, the FK506-binding proteins (FKBPs), which bind FK506 and rapamycin, and the cyclophilins, which bind cyclosporin A. Immunosuppressant actions of cyclosporin A and FK506 derive from the drug-immunophilin complex binding to and inhibiting the phosphatase calcineurin. Rapamycin binds to FKBP and the complex binds to Rapamycin And FKBP-12 Target (RAFT). RAFT affects protein translation by phosphorylating p70-S6 kinase, which phosphorylates the ribosomal S6 protein, and 4E-BP1, a repressor of protein translation initiation. Immunophilin levels are much higher in the brain than in immune tissues, and levels of FKBP12 increase in regenerating neurons in parallel with GAP-43. Immunophilin ligands, including nonimmunosuppressants that do not inhibit calcineurin, stimulate regrowth of damaged peripheral and central neurons, including dopamine, serotonin, and cholinergic neurons in intact animals. FKPB12 is physiologically associated with the ryanodine and inositol 1,4,5-trisphosphate (IP3) receptors and regulates their calcium flux. By influencing phosphorylation of neuronal nitric oxide synthase, FKBP12 regulates nitric oxide formation, which is reduced by FK506.
...
PMID:Neural roles of immunophilins and their ligands. 939 11

The immunosuppressive cyclic nonapeptide cyclolinopeptide A inhibits calcium-dependent, but not calcium-independent, activation of T lymphocytes comparably to the actions of cyclosporin A and FK506. The concentration required for complete inhibition, however, is 10 times higher than that of cyclosporin A. In addition, we demonstrate that calcineurin, a phosphatase which plays an important role in T lymphocyte signalling, is inhibited in vitro by cyclolinopeptide A by a mechanism dependent on the peptidyl-prolyl cis-trans isomerase (PPIase) cyclophilin A but not FKBP12. Direct binding of cyclolinopeptide A to cyclophilin A was confirmed using tryptophan fluorescence studies and PPIase assays. These results represent a third example of the production of a natural product that neutralises calcineurin by a mechanism dependent on the primary binding to a PPIase.
...
PMID:Cyclolinopeptide A (CLA) mediates its immunosuppressive activity through cyclophilin-dependent calcineurin inactivation. 941 31

Differentiation of leukemic HL-60 cells by all transretinoic acid (ATRA) resulted in a reduced rate of growth. Cyclosporin A and FK506, at concentrations that inhibited calcineurin activity, abrogated the ATRA-induced inhibition of HL-60 cell growth but these immunosuppressants had no effect on the ATRA-induced granulocytic differentiation. Treatment with 1 microM ATRA led to a progressive increase in calcineurin phosphatase activity of HL-60 cells; the increase in this activity appeared to parallel the functional change of HL-60 cells during granulocytic differentiation. Increase in calcineurin activity was concordant with the increased expressions of calcineurin A and calcineurin B subunit proteins. The FKBP12 expression increased during ATRA-induced differentiation and expression of cyclophilin A remained unchanged. We propose that the increased expression of calcineurin is involved in the ATRA-induced inhibition of HL-60 cell proliferation, as in the case with 1,25alpha-dihydroxy-vitamin D3.
...
PMID:Possible involvement of calcineurin in retinoic acid-induced inhibition of leukemic HL-60 cell proliferation. 947 3

FK506 binding protein (BP) 12, an immunophilin of FK506-binding proteins, is involved in intra-cellular signal transduction through the calcineurin-nuclear factor pathway. FKBP12 is reported to be associated with the ryanodine-receptor and IP3 Ca2+ channels, and to regulate cell proliferation via binding transforming growth factor (TGF)-beta receptor and cyclin dependent kinase (CDK). To elucidate the function of FKBP12 in cardiac development, we analyzed the temporal profile and regulation of FKBP12 expression in chick heart and in cultured cardiomyocytes. FKBP12 is expressed in embryos as early as day 4 and is predominantly associated with cardiomyocytes and osteo-chondrocytes. Tissue FKBP level in the heart increases with development. Immunohistochemically, the distribution and levels of FKBP12 appear to be related to sarco-endoplasmic reticulum Ca-ATPase 2 (SERCA2) but not to sarcomeric proteins. In proliferating cells, FKBP12 expression correlates with cellular mitosis, but not with DNA synthesis. In earlier embryos (< day 8), suppressing the activity of FKBP by FK506 administration is lethal, and induces cardiomegaly at later stages. In cultured cardiomyocytes, FK506 reduces the level of contractile proteins and inhibits cell proliferation. These results show that FKBP12 is enriched in cell types involved in dynamic Ca handling, and is likely an important molecule for cardiac development. FKBP12 most likely functions by affecting cellular Ca handling, since its effects are modified by modulators of Ca handling by sarcoplasmic reticulum.
...
PMID:Function of FK506 binding protein (FKBP) in chick embryonic cardiac development. 947 32

In order to mediate their effects, cyclosporin A and FK-506 must each bind with high affinity to a cytosolic target protein that belongs to the immunophilin group. FK-506 forms complexes with the FK-506 binding protein FKBP, mainly FKBP-12, and these complexes possess immunosuppressive activity through their ability to interact with another target, the abundant serine threonine phosphatase calcineurin. Evaluating the immunosuppressive activities of the FK-506 metabolites by comparing them with known immunosuppressive agents via mixed lymphocyte reaction is of clinical importance because some metabolites may retain the pharmacological activity of the parent drug or exhibit cytotoxic effects. FK-506 is metabolized by the cytochrome P-450-dependent mixed-function oxygenase system in different animal species, and we are reporting the isolation from pig liver microsomes, and the identification by electrospray ms-ms, of the FK-506 C19-C20 epoxide metabolite. We found that this new metabolite exhibits reduced in vitro immunosuppressive activity compared with FK-506 and has approximately the same immunosuppressive potency as other known immunosuppressive drugs, such as cyclosporin A and IMM-125, a hydroxyethyl derivative of D-serine cyclosporin A. We were able to demonstrate that after incubation of the FK-506 metabolite in human mixed lymphocyte reaction cultures for 6 days, the compound was stable under the conditions used for cell culture as evidenced by electrospray-ms data. A weak direct cytotoxic effect (< 30% cell death) was observed only at the highest concentrations (2500 and 5000 ng/ml), which shows that the mixed lymphocyte reaction inhibition cannot be due to a toxic effect.
...
PMID:In vitro immunosuppressive activity, isolation from pig liver microsomes and identification by electrospray ms-ms of a new FK-506 C19-C20 epoxide metabolite. 949 69

Immunophilins, protein receptors for immunosuppressant drugs such as cyclosporin A and FK506, are enriched far more in the brain than in the immune system. Drug-immunophilin complexes bind to calcineurin, inhibiting its phosphatase activity and leading to immunosuppressant effects. The immunophilin FKBP-12 (FK506 binding protein, 12 kDa) forms a complex with the ryanodine and inositol (1,4,5) trisphosphate (IP3) receptors to regulate their physiological release of intracellular Ca2+. Here, Solomon Snyder and colleagues describe how non-immunosuppressant as well as immunosuppressant immunophilin ligands are neurotrophic for numerous classes of damaged neurones, both in culture systems and intact animals. Their ability to stimulate functional regrowth of damaged sciatic, cortical cholinergic, dopamine and 5-HT neurones may have therapeutic relevance.
...
PMID:Neural actions of immunophilin ligands. 950 98

The effects of insulin on the mammalian target of rapamycin, mTOR, were investigated in 3T3-L1 adipocytes. mTOR protein kinase activity was measured in immune complex assays with recombinant PHAS-I as substrate. Insulin-stimulated kinase activity was clearly observed when immunoprecipitations were conducted with the mTOR antibody, mTAb2. Insulin also increased by severalfold the 32P content of mTOR that was determined after purifying the protein from 32P-labeled adipocytes with rapamycin.FKBP12 agarose beads. Insulin affected neither the amount of mTOR immunoprecipitated nor the amount of mTOR detected by immunoblotting with mTAb2. However, the hormone markedly decreased the reactivity of mTOR with mTAb1, an antibody that activates the mTOR protein kinase. The effects of insulin on increasing mTOR protein kinase activity and on decreasing mTAb1 reactivity were abolished by incubating mTOR with protein phosphatase 1. Interestingly, the epitope for mTAb1 is located near the COOH terminus of mTOR in a 20-amino acid region that includes consensus sites for phosphorylation by protein kinase B (PKB). Experiments were performed in MER-Akt cells to investigate the role of PKB in controlling mTOR. These cells express a PKB-mutant estrogen receptor fusion protein that is activated when the cells are exposed to 4-hydroxytamoxifen. Activating PKB with 4-hydroxytamoxifen mimicked insulin by decreasing mTOR reactivity with mTAb1 and by increasing the PHAS-I kinase activity of mTOR. Our findings support the conclusion that insulin activates mTOR by promoting phosphorylation of the protein via a signaling pathway that contains PKB.
...
PMID:Evidence of insulin-stimulated phosphorylation and activation of the mammalian target of rapamycin mediated by a protein kinase B signaling pathway. 963 26

Calcineurin is a widely distributed protein phosphatase regulated by calcium and calmodulin. It mediates the immunosuppressive actions of drugs such as cyclosporin and FK506, and has been implicated in a number of calcium-sensitive pathways in the nervous system, including regulation of neurotransmitter release and modulation of long-term changes in synaptic plasticity. Calcineurin associates physiologically with other proteins, including calmodulin, FKBP12 (FK506-binding protein), the ryanodine receptor, and the inositol 1,4,5-trisphosphate receptor. We now report the identification, molecular cloning, and functional characterization of a novel protein, cain (calcineurin inhibitor), that interacts with and inhibits calcineurin. The full-length cain cDNA predicts a 240-kDa protein with no significant homology to any known protein. Cain associates with calcineurin both in vitro and in vivo, leading to a non-competitive inhibition of calcineurin activity. The putative calcineurin-binding domain of cain, a 38-amino acid region defined by mutational analysis, is highly basic. Like calcineurin, cain has a prominent neuronal expression and a wide tissue distribution. Cain's expression pattern in the brain closely resembles that of calcineurin, indicating a physiologic association between the two proteins.
...
PMID:Cain, a novel physiologic protein inhibitor of calcineurin. 966 Jul 98

Transcription factors belonging to the nuclear factor of activated T cells (NFAT) family regulate the expression of cytokine genes and other inducible genes during the immune response. The functions of NFAT proteins are directly controlled by the calcium- and calmodulin-dependent phosphatase calcineurin. Here we show that the binding of calcineurin to NFAT is substantially increased when calcineurin is activated with calmodulin and calcium. FK506.FKBP12 drug-immunophilin complexes inhibited the interaction of NFAT with activated calcineurin much more effectively than they inhibited the interaction with inactive calcineurin, suggesting that part of the interaction with activated calcineurin involved the enzyme active site. We have previously shown that NFAT is targeted to inactive calcineurin at a region distinct from the calcineurin active site (Aramburu, J., Garcia-Cozar, F. J., Raghavan, A., Okamura, H., Rao, A., and Hogan, P. G. (1998) Mol. Cell 1, 627-637); this region is also involved in NFAT binding to activated calcineurin, since binding is inhibited by an NFAT peptide spanning the calcineurin docking site on NFAT. The interacting surfaces are located on the catalytic domain of the calcineurin A chain and on an 86-amino acid fragment of the NFAT regulatory domain. NFAT binding to the calcineurin catalytic domain was inhibited by the calcineurin autoinhibitory domain and the RII substrate peptide, which bind in the calcineurin active site, as well as by the NFAT docking site peptide, which binds to a region of calcineurin distinct from the active site. We propose that, in resting cells, NFAT is targeted to a region of the calcineurin catalytic domain that does not overlap the calcineurin active site. Upon cell activation, displacement of the autoinhibitory domain by calmodulin binding allows NFAT to bind additionally to the calcineurin active site, thus positioning NFAT for immediate dephosphorylation at functional phosphoserine residues.
...
PMID:Two-site interaction of nuclear factor of activated T cells with activated calcineurin. 972


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

---