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)

The opening and closing of chloride (Cl-) channels in the apical membrane of epithelial cells is regulated by hormones, neurotransmitters and enterotoxins (intestine) acting through a variety of intracellular messengers, including cyclic nucleotides (cAMP, cGMP), calcium (Ca) and diacylglycerol (DAG). The chloride impermeability of epithelial membranes observed in cystic fibrosis (CF) patients does not result from a defect in the Cl- conducting properties of the channel or in channel recruitment but stems either from a defect in a key regulator of the channel, presumably a phosphoprotein, or from the hyperactivation of a channel closing mechanism, presumably a protein phosphatase or a down-regulating protein kinase (i.e. protein kinase C). In vitro phosphorylation of isolated intestinal brush border membranes has revealed the existence of a 25,000 molecular weight proteolipid (p25) acting as cosubstrate for both cGMP- and cAMP-dependent protein kinases and cross-reacting with antibodies directed against the cytoplasmic tail of the band 3 anion exchanger from erythrocytes. The putative role of p25 in Cl- channel regulation and its relationship to an unidentified GTP-binding protein recently implicated in Cl- channel activation is discussed on the basis of a regulatory model indicating potential sites of the CF defect at a molecular level.
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PMID:The molecular basis of chloride channel dysregulation in cystic fibrosis. 270 19

alpha 1-Adrenergic (alpha 1-AR) agents stimulate NaCl(K) cotransport and phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P2]-specific phospholipase C in human trachea and nasal polyp epithelial cells. One second messenger generated by PtdIns(4,5)P2 degradation is inositol trisphosphate. We now show that diglycerides (DG) are also generated during alpha 1-AR stimulation. In cells prelabeled with [3H]arachidonic acid, alpha 1-AR agents produced a biphasic DG generation in normal and cystic fibrosis (CF) cells that is blocked by pertussis toxin. The early DG peak closely paralleled PtdIns(4,5)P2 degradation, stimulation of cotransport by phorbol 12-myristate 13-acetate (PMA), and inhibition of cotransport by the protein kinase C (PKC) inhibitor staurosporine. This suggests that cotransporter activation requires PKC-protein phosphorylation. This possibility was tested using the protein phosphatase inhibitor okadaic acid. Okadaic acid elevated bumetanide-sensitive Cl efflux. Staurosporine also blocked > 63% of okadaic-acid-stimulated Cl transport. The late DG peak did not support hormone-stimulated cotransport. The results demonstrate that DGs are a pivotal link between alpha 1-AR stimulation and NaCl(K) cotransport activation with a role for PKC and protein phosphorylation. alpha 1-AR intracellular signaling mechanisms apparently operate normally in CF cells.
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PMID:The role of protein kinase C in alpha-adrenergic regulation of NaCl(K) cotransport in human airway epithelial cells. 790 Aug 23

cAMP-dependent phosphorylation activates the cystic fibrosis transmembrane conductance regulator (CFTR) in epithelia. However, the protein phosphatase (PP) that dephosphorylates and inactivates CFTR in airway and intestinal epithelia, two major sites of disease, is not certain. We found that in airway and colonic epithelia, neither okadaic acid nor FK506 prevented inactivation of CFTR when cAMP was removed. These results suggested that a phosphatase distinct from PP1, PP2A, and PP2B was responsible. Because PP2C is insensitive to these inhibitors, we tested the hypothesis that it regulates CFTR. We found that PP2Calpha is expressed in airway and T84 intestinal epithelia. To test its activity on CFTR, we generated recombinant human PP2Calpha and found that it dephosphorylated CFTR and an R domain peptide in vitro. Moreover, in cell-free patches of membrane, addition of PP2Calpha inactivated CFTR Cl- channels; reactivation required readdition of kinase. Finally, coexpression of PP2Calpha with CFTR in epithelia reduced the Cl- current and increased the rate of channel inactivation. These results suggest that PP2C may be the okadaic acid-insensitive phosphatase that regulates CFTR in human airway and T84 colonic epithelia. It has been suggested that phosphatase inhibitors could be of therapeutic value in cystic fibrosis; our data suggest that PP2C may be an important phosphatase to target.
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PMID:Protein phosphatase 2C dephosphorylates and inactivates cystic fibrosis transmembrane conductance regulator. 938 Jul 58

The effect of genistein on anion secretion via cystic fibrosis transmembrane conductance regulator (CFTR) in cultured rat cauda epididymal epithelia was studied by short-circuit current (Isc) technique. Genistein added apically stimulated a concentration-dependent rise in Isc due to Cl(-) and HCO(3)(-) secretion. The genistein-induced Isc was observed in basolaterally permeabilized monolayers, suggesting that the Isc response was mediated by the apical anion channel. The response could be blocked by the nonspecific Cl(-) channel blocker, diphenylamine-2-carboxylate (DPC), but not by the Ca(2+)-activated Cl(-) channel blocker, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS). Genistein did not increase intracellular cAMP, but H-89, a protein kinase A inhibitor, completely abolished the Isc response to genistein. Moreover, pretreatment of the tissues with MDL-12330A, an adenylate cyclase inhibitor, markedly attenuated the Isc response to genistein, but the response was restored upon the addition of exogenous cAMP. Ca(2+), protein kinase C, tyrosine kinase, and protein phosphatase signalling pathways were not involved in the action of genistein. It is speculated that genistein stimulates anion secretion by direct interaction with CFTR. This requires a low level of phosphorylation of CFTR by basal protein kinase A activity. It is suggested that genistein may provide therapeutic benefit to male infertility associated with cystic fibrosis.
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PMID:Activation of cystic fibrosis transmembrane conductance regulator in rat epididymal epithelium by genistein. 1061 Oct 78

The search for differentially expressed genes in gastric cancer may help define molecular alterations and molecular diagnosis of gastric cancer. Using the differential display PCR technique, we identified 18 genes that are differentially expressed between normal and tumor human gastric tissues. Their expressions were verified with reverse Northern blot analysis and Northern blot analysis. Oxidative phosphorylation-related genes, antizyme inhibitor of ornithine decarboxylase, protein phosphatase-1beta, 35-kDa peroxisomal membrane protein, and cystic fibrosis transmembrane conductance receptor were highly expressed in tumor tissue, whereas pepsinogen A, Na-K ATPase alpha subunit, nerve growth factor receptor, and alpha-tropomyosin were highly expressed in normal tissue. In addition, 3 unknown genes were found to be differentially expressed in paired gastric tissues. These differentially expressed genes may provide significant opportunities for further understanding of gastric carcinogenesis and the molecular diagnosis of gastric cancer.
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PMID:Identification of differentially expressed genes in normal and tumor human gastric tissue. 1105 45

Cystic fibrosis transmembrane conductance regulator (CFTR) chloride channels are regulated tightly by protein kinases and phosphatases. The regulatory domain of CFTR has about 20 potential sites for phosphorylation by protein kinases A (PKA) and C (PKC). The reason for this large number of sites is not known, however their conservation from fish to humans implies that they play important roles in vivo. PKA is an important activator, and its stimulation of CFTR is enhanced by PKC via mechanisms which are not fully understood. The physiological stimuli of CFTR are not known for some epithelia, and it appears likely that other serine/threonine and even tyrosine kinases also regulate CFTR in particular tissues. Phosphatases that deactivate CFTR have yet to be identified definitively at the molecular level, however CFTR is regulated by a membrane-bound form of protein phosphatase-2C (PP2C) in several cell types. Patch-clamp studies of channel rundown, co-immunoprecipitation, chemical cross-linking studies, and pull-down assays all indicate that CFTR and PP2C are closely associated within a stable regulatory complex. Understanding the regulation of CFTR by PP2C is a priority due to its potential as a target for pharmacotherapies in the treatment of cystic fibrosis.
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PMID:Regulation of the CFTR channel by phosphorylation. 1184 11

Serine/threonine protein phosphatases have long been ignored as potential therapeutic targets for two reasons, one the biochemical significance of these proteins has not been appreciated and two, many natural protein phosphatase inhibitors are potent toxins and are considered unsuitable for clinical use. This review outlines the biochemical role of this protein family in cancer, cystic fibrosis, immunosuppression and, cardiac and neurological disorders. Particular emphasis is also given to the synthesis of selective small molecule inhibitors and their clinical exploitation.
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PMID:Small molecule inhibitors of serine/threonine protein phosphatases. 1236 90

In the last few years, novel immunosuppressive agents and new formulations, including sirolimus, mycophenolic acid (the active metabolite of mycophenolate mofetil), tacrolimus, and microemulsion cyclosporine, have significantly improved the clinical outcome of transplant recipients. However, the majority of immunosuppressive agents need a constant monitoring of drug levels to reduce the risk of graft rejection as well as drug-induced toxicities. Many factors may affect the pharmacokinetic characteristics of immunosuppressive agents, potentially reducing treatment effectiveness. Absorption and metabolism of immunosuppressive drugs are influenced by patient genotype and comedications, while comorbidities (ie, diabetes and cystic fibrosis) are responsible for altered pharmacokinetics. Dose individualization in transplant recipients is performed according to their health status, graft function, and drug therapeutic range. With respect to the last issue, therapeutic drug monitoring (TDM) plays a crucial role in achieving optimal immunosuppression, improving the efficacy of drugs, and lowering toxic effects. Pharmacokinetic analysis allowed the identification of specific parameters, such as plasma or blood levels, immediately before dosing (C(min) or trough levels) or 2 hours after administration (C(2)), which are significantly related to tissue exposure to the drug. More recently, studies have investigated treatment individualization by evaluating drug pharmacogenetics based on the expression level or mutations of their molecular targets, including calcineurin for cyclosporine and tacrolimus, and inosine monophosphate dehydrogenase for mycophenolic acid. Although no conclusive data may be drawn from these preliminary trials, further studies are underway to address the role of pharmacogenetics in clinical decision making.
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PMID:Prospects for personalized immunosuppression: pharmacologic tools--a review. 1511 Jun 31

Cystic fibrosis results from mutations in the cystic fibrosis conductance regulator protein (CFTR), a cAMP/protein kinase A (PKA) and ATP-regulated Cl(-) channel. CFTR is increasingly recognized as a component of multiprotein complexes and although several inhibitory proteins to CFTR have been identified, protein complexes that stimulate CFTR function remain less well characterized. We report that annexin 2 (anx 2)-S100A10 forms a functional cAMP/PKA/calcineurin (CaN)-dependent complex with CFTR. Cell stimulation with forskolin/3-isobutyl-1-methylxanthine significantly increases the amount of anx 2-S100A10 that reciprocally coimmunoprecipitates with cell surface CFTR and calyculin A. Preinhibition with PKA or CaN inhibitors attenuates the interaction. Furthermore, we find that the acetylated peptide (STVHEILCKLSLEG, Ac1-14), but not the nonacetylated equivalent N1-14, corresponding to the S100A10 binding site on anx 2, disrupts the anx 2-S100A10/CFTR complex. Analysis of 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) and CFTR(inh172)-sensitive currents, taken as indication of the outwardly rectifying Cl(-) channels (ORCC) and CFTR-mediated currents, respectively, showed that Ac1-14, but not N1-14, inhibits both the cAMP/PKA-dependent ORCC and CFTR activities. CaN inhibitors (cypermethrin, cyclosporin A) discriminated between ORCC/CFTR by inhibiting the CFTR(inh172)-, but not the DIDS-sensitive currents, by >70%. Furthermore, peptide Ac1-14 inhibited acetylcholine-induced short-circuit current measured across a sheet of intact intestinal biopsy. Our data suggests that the anx 2-S100A10/CFTR complex is important for CFTR function across epithelia.
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PMID:The formation of the cAMP/protein kinase A-dependent annexin 2-S100A10 complex with cystic fibrosis conductance regulator protein (CFTR) regulates CFTR channel function. 1758 60

Cystic fibrosis (CF) is characterised by impaired epithelial ion transport and is caused by mutations in the cystic fibrosis conductance regulator protein (CFTR), a cAMP/PKA and ATP-regulated chloride channel. We recently demonstrated a cAMP/PKA/calcineurin (CnA)-driven association between annexin 2 (anx 2), its cognate partner -S100A10 and cell surface CFTR. The complex is required for CFTR and outwardly rectifying chloride channel function in epithelia. Since the cAMP/PKA-induced Cl(-) current is absent in CF epithelia, we hypothesized that the anx 2-S100A10/CFTR complex may be defective in CFBE41o cells expressing the commonest F508del-CFTR (DeltaF-CFTR) mutation. Here, we demonstrate that, despite the presence of cell surface DeltaF-CFTR, cAMP/PKA fails to induce anx 2-S100A10/CFTR complex formation in CFBE41o- cells homozygous for F508del-CFTR. Mechanistically, PKA-dependent serine phosphorylation of CnA, CnA-anx 2 complex formation and CnA-dependent dephosphorylation of anx 2 are all defective in CFBE41o- cells. Immunohistochemical analysis confirms an abnormal cellular distribution of anx 2 in human and CF mouse epithelia. Thus, we demonstrate that cAMP/PKA/CnA signaling pathway is defective in CF cells and suggest that loss of anx 2-S100A10/CFTR complex formation may contribute to defective cAMP/PKA-dependent CFTR channel function.
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PMID:Defective formation of PKA/CnA-dependent annexin 2-S100A10/CFTR complex in DeltaF508 cystic fibrosis cells. 1834 74


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