Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

NFAT transcription factors are highly phosphorylated proteins that are regulated by the calcium-dependent phosphatase calcineurin. We show by mass spectrometry that NFAT1 is phosphorylated on fourteen conserved phosphoserine residues in its regulatory domain, thirteen of which are dephosphorylated upon stimulation. Dephosphorylation of all thirteen residues is required to mask a nuclear export signal (NES), cause full exposure of a nuclear localization signal (NLS), and promote transcriptional activity. An inducible phosphorylation site in the transactivation domain contributes to transcriptional activity. Our data suggest that dephosphorylation promotes NFAT1 activation by increasing the probability of an active conformation, in a manner analogous to that by which depolarization increases the open probability of voltage-gated ion channels. This conformational switch paradigm may explain modification-induced functional changes in other heavily phosphorylated proteins.
Mol Cell 2000 Sep
PMID:Concerted dephosphorylation of the transcription factor NFAT1 induces a conformational switch that regulates transcriptional activity. 1103 Mar 34

In order to explain the schistosomicidal effect of cyclosporin A, the hypothesis was advanced that the drug, complexed with cyclophilin, inhibits the phosphatase activity of parasite calcineurin (CN), with mechanisms similar to those operating in its immunosuppressive action. As a preparatory step to the testing of this hypothesis, we report the molecular cloning of both CN subunits in Schistosoma mansoni. The catalytic (A) subunit has a predicted sequence of 607 amino acids and shows substantial similarity to other cloned CNs, except for the carboxy-terminal end that is highly divergent. The regulatory (B) subunit consists of 169 amino acids that are 86% identical to those of the human counterpart and, from its anomalous electrophoretic mobility, it appears to be myristoylated. The results of Southern blotting experiments are compatible with the existence of multiple genes for CNA and a single gene for CNB. Western blots showed that both subunits are present at all stages of the parasite life cycle and can be detected both in the soluble and in the membrane fraction. Immunofluorescence confocal microscopy revealed a striking concentration of the anti-CNA reactivity in 6-8 discrete spots in the schistosomula and in distinct spots along the body of the adult parasite, corresponding to the expected localization of flame cells. Both patterns were confirmed by a perfect co-localization of the anti-CNA signal with that of a previously characterized anti-flame cell monoclonal antibody. The preferential confinement of schistosome CN to the protonephridial system suggests that the enzyme in the parasite may fulfil similar functions to those performed in mammalian kidneys.
Mol Biochem Parasitol 2000 Oct
PMID:Molecular cloning of Schistosoma mansoni calcineurin subunits and immunolocalization to the excretory system. 1107 Dec 87

HSF-1 is regulated at multiple molecular levels through intra- and intermolecular protein-protein interactions as well as by post-translational modification through phosphorylation. We have found that elevating intracellular calcium ion levels by exposure to the ionophore A23187 or thapsigargin inhibits the conversion of HSF-1 from a latent cytoplasmic form to its nuclear/DNA binding form. To examine a role for calcium/calmodulin regulated enzymes in this process, we examined the ability of specific inhibitors to abrogate the effects of calcium elevation. While the inhibitor of calmodulin dependent kinase II, KCN62 enhanced activation of HSF-1 during heat shock, it failed to block the inhibitory effects of calcium increase. By contrast, the immunosuppresant drugs cyclosporin A and FK506 abolished the effects of calcium elevation on HSF-1 activation. As the biological effects of the drugs are effected through inhibition of the calcium/calmodulin regulated phosphatase calcineurin, this suggests a role for calcineurin in antagonizing HSF-1 activity. The experiments suggest the existence of phosphorylated residue(s) in HSF-1 important in one or more of the processes that lead to activation (trimerization, nuclear localization, DNA binding) and which becomes dephosphorylated due to the activation of a calcium/calmodulin/calcineurin complex.
Int J Mol Med 2000 Dec
PMID:Role of calcium activated kinases and phosphatases in heat shock factor-1 activation. 1107 32

The role of HSP90 in stress tolerance was investigated in Saccharomyces cerevisiae. Cells showing 20-fold overexpression of Hsc82, an HSP90 homologue in yeast, were hypersensitive to high-NaCl or H-LiCl stresses. Hsc82-overexpressing cells appeared similar to calcineurin-defective cells in salt sensitivity and showed reduced levels of calcineurin-dependent gene expression. Co-overexpression of Cna2, the catalytic subunit of calcineurin, suppressed the hypersensitivity. Cna2 and Hsc82 coimmunoprecipitated from control cells grown under normal conditions but not from stressed cells. In contrast, coimmunoprecipitation was detected with Hsc82-overexpressing cells even after exposure to stresses. Cna2 immune complexes from stressed control cells showed a significant level of calcineurin activity, whereas those from stressed Hsc82-overexpressing cells did not. Treatment of extracts from Hsc82-overexpressing cells with Ca(2+)-calmodulin increased the calcineurin activity associated with Cna2 immune complexes. Geldanamycin, an inhibitor of HSP90 abolished the coimmunoprecipitation but did not activate calcineurin. When the expression level of Hsc82 decreased to below 30% of the normal level, cells also became hypersensitive to salt stress. In these cells, the amount of Cna2 was reduced, likely as a result of degradation. The present results showed that Hsc82 binds to and stabilizes Cna2 and that dissociation of Cna2 from Hsc82 is necessary for its activation.
Mol Cell Biol 2000 Dec
PMID:Role of HSP90 in salt stress tolerance via stabilization and regulation of calcineurin. 1109 77

Cardiac-specific expression of an activated calcineurin protein in the hearts of transgenic (CLN) mice produces a profound hypertrophy that rapidly progresses to heart failure. While calcineurin is regulated by Ca2+, the potential effects of calcineurin on cardiac myocyte Ca2+ handling has not been evaluated. To this end, we examined L-type Ca2+ currents (I(Ca)) in left ventricular myocytes. CLN myocytes had larger (approximately 80%) cell capacitance and enhanced I(Ca) density (approximately 20%) compared with non-transgenic (NTG) littermates, but no change in the current-voltage relationship, single-channel conductance or protein levels of alpha 1 or beta 2 subunit of L-type Ca2+ channels. Interestingly, the kinetics of I(Ca) inactivation was faster (approximately two-fold) in CLN myocytes compared with NTG myocytes. Ryanodine application slowed the rate of I(Ca) inactivation in both groups and abolished the kinetic difference, suggesting that Ca2+ dependent inactivation is increased in CLN myocytes due to altered SR Ca2+ release. Treatment of CLN mice with Cyclosporine A (CsA), a calcineurin inhibitor, prevented myocyte hypertrophy and changes in I(Ca) activity and inactivation kinetics. However, there was no direct effect of CsA on I(Ca) in either NTG or CLN myocytes, suggesting that endogenous calcineurin activity does not directly regulate Ca2+ channel activity. This interpretation is consistent with the observation that I(Ca) density, inactivation kinetics and regulation by isoproterenol were normal in cardiac-specific transgenic mice expressing calcineurin inhibitory protein domains from either Cain or AKAP79. Taken together these data suggest that chronic activation of calcineurin is associated with myocyte hypertrophy and a secondary enhancement of intracellular Ca2+ handling that is tied to the hypertrophy response itself.
J Mol Cell Cardiol 2001 Feb
PMID:Enhanced Ca2+ channel currents in cardiac hypertrophy induced by activation of calcineurin-dependent pathway. 1116 30

Calcineurin is a Ca2+-calmodulin-regulated protein phosphatase that is the target of the immunosuppressive drugs cyclosporin A and FK506. Calcineurin is a heterodimer composed of a catalytic A and a regulatory B subunit. In previous studies, the calcineurin A homologue was identified and shown to be required for growth at 37 degrees C and hence for virulence of the pathogenic fungus Cryptococcus neoformans. Here, we identify the gene encoding the calcineurin B regulatory subunit and demonstrate that calcineurin B is also required for growth at elevated temperature and virulence. We show that the FKR1-1 mutation, which confers dominant FK506 resistance, results from a 6 bp duplication generating a two-amino-acid insertion in the latch region of calcineurin B. This mutation was found to reduce FKBP12-FK506 binding to calcineurin both in vivo and in vitro. Molecular modelling based on the FKBP12-FK506-calcineurin crystal structure illustrates how this mutation perturbs drug interactions with the phosphatase target. In summary, our studies reveal a central role for calcineurin B in virulence and antifungal drug action in the human fungal pathogen C. neoformans.
Mol Microbiol 2001 Feb
PMID:Calcineurin regulatory subunit is essential for virulence and mediates interactions with FKBP12-FK506 in Cryptococcus neoformans. 1125 6

Calcium (Ca2+) ions are second messengers in signaling pathways in all types of cells. They regulate muscle contraction, electrical signals which determine the cardiac rhythm and cell growth pathways in the heart. In the past decade cDNA cloning has provided clues as to the molecular structure of the intracellular Ca2+ release channels (ryanodine receptors, RyR, and inositol 1,4,5-trisphosphate receptors, IP3R) on the sarcoplasmic and endoplasmic reticulum (SR/ER) and an understanding of how these molecules regulate Ca2+ homeostasis in the heart is beginning to emerge. The intracellular Ca2+ release channels form a distinct class of ion channels distinguished by their structure, size, and function. Both RyRs and IP3Rs have gigantic cytoplasmic domains that serve as scaffolds for modulatory proteins that regulate the channel pore located in the carboxy terminal 10% of the channel sequence. The channels are tetramers comprised of four RyR or IP3R subunits. RyR2 is required for excitation-contraction (EC) coupling in the heart. Using co-sedimentation and co-immunoprecipitation we have defined a macromolecular complex comprised of RyR2, FKBP12.6, PKA, the protein phosphatases PP1 and PP2A, and an anchoring protein mAKAP. We have shown that protein kinase A (PKA) phosphorylation of RyR2 dissociates FKBP12.6 and regulates the channel open probability (P(o)). In failing human hearts RyR2 is PKA hyperphosphorylated resulting in defective channel function due to increased sensitivity to Ca2+-induced activation.
J Mol Cell Cardiol 2001 Apr
PMID:Ryanodine receptors/calcium release channels in heart failure and sudden cardiac death. 1127 16

Signals generated by both antigen and cytokines binding to CD4(+) T cells synergize to promote helper T cell subset differentiation. For Th2 cell commitment neither IL-4 nor T cell receptor (TCR) stimulation are sufficient to drive differentiation. Th2 differentiation requires IL-4-receptor mediated signal transducers and activators of transcription 6 (STAT6) activation, but the possibility that IL-4 can directly enhance IL-4 production by T cells has remained unclear. In this report, IL-4 is shown to increase anti-CD3 or ionomycin induced IL-4 mRNA in differentiated murine Th2 cells. Anti-CD3 or ionomycin also enhances IL-4 induction of STAT6 activation, assayed by gel shift analysis of nuclear lysates. Surprisingly, cyclosporin A (CsA) also enhances STAT6 induction. Both ionomycin and CsA also enhance IL-4-induced transcriptional activity of a STAT6-linked promoter-reporter construct. In vitro calcineurin activity reduces STAT6 interactions with DNA, and CsA or FK506 can block this effect of calcineurin. These results indicate that IL-4 and TCR-generated calcium signals interact to maximize IL-4 gene expression and STAT6 activity. Calcineurin-mediated serine dephosphorylation of STAT6 and STAT6 serine phosphorylation may counter-regulate transcriptional activity of STAT6.
Mol Immunol
PMID:Integration of TCR and IL-4 signals through STAT6 and the regulation of IL-4 gene expression. 1127 61

Calcineurin is a Ca2+- and calmodulin-regulated protein phosphatase that is important in Ca2+-mediated signal transduction. Recent application of the powerful techniques of molecular genetics has demonstrated that calcineurin is involved in the regulation of critical biological processes such as T cell activation, muscle hypertrophy, memory development, glucan synthesis, ion homeostasis, and cell cycle control. Notably, specific transcription factors have been shown to play a key role in regulating these functions, and their calcineurin-mediated dephosphorylation and nuclear translocation appear to be a central event in the signal transduction pathways. This review focuses on recent progress in these areas and discusses the evidence for cross-talk between calcineurin and other signaling pathways.
Cell Mol Life Sci 2001 Feb
PMID:Molecular genetic analysis of the calcineurin signaling pathways. 1128 9

In this study we demonstrate for the first time that a novel indexing-based differential display technique generates valid and reproducible results when applied to human post-mortem tissue. We studied expression profiles in prefrontal cortex tissue derived from Alzheimer's disease (AD) and control brains, respectively, and found robust changes in several expressed genes, some of which have a known association with the disease process in AD. These included the dramatic reduction of calcineurin (known to be involved in tau phosphorylation) and GAP-43 (associated with synapse remodelling). Differential display results were confirmed by semi-quantitative RT-PCR on a larger number of brains.
Brain Res Mol Brain Res 2001 Mar 31
PMID:Indexing-based differential display--studies on post-mortem Alzheimer's brains. 1129 49


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