Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.16 (calcineurin)
 17,112 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Interleukin 1-beta (IL-1beta) induces apoptosis in a glioblastoma-derived human cell line, exhibiting a poorly differentiated astrocytic phenotype. The apoptotic effect was demonstrated by analyzing nuclear morphology, in situ DNA fragmentation, and by ELISA detection of cytoplasmatic nucleosomes. We correlated the degree of differentiation of GL15 cells with the apoptotic response: 1) 4',6-diamidino-2-phenylindole staining, combined with glial fibrillary acidic protein (GFAP) immunofluorescence, showed that the cells with apoptotic nuclei express low levels of GFAP; and 2) at 13 days of subculture, in a more differentiated state, GL15 cells did not respond with apoptosis to IL-1beta. In this cell line, nonrandom chromosome changes and the expression of SV40 early region have been previously shown. The involvement of p42/p44 mitogen-activated protein kinase (MAPK) pathway in the induction of apoptosis by IL-1beta was hypothesized. Previous studies have shown that SV40 small T antigen partially inhibits phosphatase 2A, leading to an enhancement of the steady-state activity of p42/p44 MAPK pathway. PD-098059, specific inhibitor of p42/p44 MAPK pathway, counteracts the apoptotic effect of IL-1beta, whereas SB-203580, specific inhibitor of p38 stress-activated protein kinase (SAPK) pathway, is ineffective. The imbalance between MAPK and SAPK pathways has been proposed as a key factor in determination of cell fate. Our results demonstrate that a further stimulation of p42/p44 MAPK pathway can constitute a death signal in tumor cells in which genomic damage and MAPK pathway control alterations occur.
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PMID:Interleukin-1beta induces apoptosis in GL15 glioblastoma-derived human cell line. 1107 22

Insulin receptor-substrate-1 (IRS-1) is a docking protein for several tyrosine kinase receptors. Upon tyrosine phosphorylation, IRS-1 binds to signaling molecules that express Src homology 2 (SH-2) binding domains, including phosphatidylinositol 3-kinase (PI 3-kinase), phosphotyrosine phosphatase SHP-2 (Syp), Nck, Crk and Grb-2. Hydrogen peroxide (H(2)O(2)) induces tyrosine phosphorylation of key signaling mediators presumably by inhibition of tyrosine phosphatases. In many cell types, the activation of extracellular signal-related kinases (e.g. MAPK) and other protein kinases by H(2)O(2) leads to transcriptional activation. In the current study, we examined the effect of H(2)O(2) on IRS-1 tyrosine phosphorylation in primary cultured rat cerebellar granule neurons. H(2)O(2) stimulated the rapid tyrosine phosphorylation of IRS-1 and p42/p44 MAP kinase, and induced its association with PI 3-kinase. H(2)O(2)-induced IRS-1 phosphorylation was rapidly reversible (5 min) whereas MAPK phosphorylation persisted for up to 1 h. NMDA reversed H(2)O(2)-mediated tyrosine phosphorylation of IRS-1 and its association with PI 3-kinase. The dephosphorylation of IRS-1 by NMDA was calcium-dependent and was inhibited by the calcineurin inhibitor cyclosporine. Calmodulin-dependent tyrosine phosphatase activity of calcineurin was observed in vitro using both immunoprecipitated and recombinant tyrosine-phosphorylated IRS-1 as substrates. These data highlight the role of multiple phosphatases in the regulation of IRS-1 tyrosine phosphorylation and identify a novel functional property of calcineurin.
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PMID:Tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) by oxidant stress in cerebellar granule neurons: modulation by N-methyl-D-aspartate through calcineurin activity. 1127 62

Cytosolic phospholipase A(2)-alpha (cPLA(2)-alpha) is a calcium-sensitive enzyme involved in receptor-mediated eicosanoid production. In resting cells, cPLA(2)-alpha is present in the cytosol and nucleus and translocates to membranes via its calcium-dependent lipid-binding (CaLB) domain following stimulation. cPLA(2)-alpha is also regulated by phosphorylation on several residues, which results in enhanced arachidonic acid release. Little is known about the factors controlling the nuclear localisation of cPLA(2)-alpha. Here the nuclear localisation of cPLA(2)-alpha in the EA.hy.926 human endothelial cell line was investigated. Nuclear localisation was dependent on proliferation, with subconfluent cells containing higher levels of nuclear cPLA(2)-alpha than contact-inhibited confluent or serum-starved cells. The broad-range protein kinase inhibitor staurosporine caused a decrease in the nuclear level of cPLA(2)-alpha, whereas the protein phosphatase inhibitor okadaic acid increased the level of nuclear cPLA(2)-alpha. Using inhibitors for specific mitogen-activated protein (MAP) kinases, both p42/44(MAPK) and p38(MAPK) were shown to be important in modulating nuclear localisation. Finally, inhibition of nuclear import and export using Agaricus bisporus lectin and leptomycin B, respectively, demonstrated that cPLA(2)-alpha contains functional nuclear localisation and export signals. Thus we have identified a novel mode of regulation of cPLA(2)-alpha. This, together with the increasing body of evidence supporting the role of nuclear lipid second messengers in gene expression and proliferation, may have important implications for controlling the growth of endothelial cells in angiogenesis and tumour progression.
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PMID:Nuclear localisation of cytosolic phospholipase A2-alpha in the EA.hy.926 human endothelial cell line is proliferation dependent and modulated by phosphorylation. 1241 98

The earthworm-derived chemoattractant ES20 interacts with its G-protein-coupled receptors on the plasma membrane of vomeronasal (VN) sensory neurons of garter snakes, resulting in an increase in inositol trisphosphate [J. Biol. Chem. 269 (1994) 16867] and a rapid phosphorylation of the membrane-bound proteins, p42/44 [Biochim. Biophys. Acta 1450 (1999) 320]. The phosphorylation of p42/44 proteins are countervailingly regulated by a protein kinase and an okadaic acid-insensitive but fluoride-sensitive protein phosphatase (PPase) [J. Liu et al. (loc. cit.)]. The phosphorylation of p42/44 induced by ES20 appears to play a role in the regulation of signal transduction pathways by modulating the GTPase activity [J. Liu et al. (loc. cit.)]. A 564-bp fragment of cDNA was obtained from VN RNA of garter snakes by reverse transcription polymerase chain reaction with degenerate primers. The 564-bp fragment was amplified, cloned, and sequenced. Northern blot analysis revealed that both the VN organ (VNO) and brain contained the gene of PPase 2C. A full-length complementary 4119-bp DNA containing an open reading frame of 1146bp that encodes a protein of 382 amino acids with a molecular mass of 49,123Da was obtained from the VN cDNA library of garter snakes. The deduced amino acid sequence showed 88% amino acid identity to bovine protein phosphatase 2C alpha and 87% identity to human and rat PP2C alpha and to Mg(2+)-dependent protein phosphatase 1A of rat and rabbit. In situ hybridization revealed that the mRNA of VN protein phosphatase 2C is expressed in the vomeronasal sensory epithelium. This is the first report of the identification of a type 2C serine/threonine protein phosphatase in the VN system.
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PMID:Molecular cloning and characterization of protein phosphatase 2C of vomeronasal sensory epithelium of garter snakes. 1246 70

Protein phosphorylation has pivotal roles in ABA and osmotic stress signaling in higher plants. Two protein phosphatase genes, ABI1 and ABI2, are known to regulate these signaling pathways in Arabidopsis: The identity of ABA-activated protein kinases required for the ABA signaling, however, remains to be elucidated. Here we demonstrate that two protein kinases, p44 and p42, were activated by ABA in Arabidopsis T87 cultured cells, and at least one protein kinase, p44, was activated not only by ABA but also by low humidity in Arabidopsis plants. Analysis of T-DNA knockout mutants and biochemical analysis using a specific antibody revealed that the p44 is encoded by a SnRK2-type protein kinase gene, SRK2E. The srk2e mutation resulted in a wilty phenotype mainly due to loss of stomatal closure in response to a rapid humidity decrease. ABA-inducible gene expression of rd22 and rd29B was suppressed in srk2e. These results show that SRK2E plays an important role in ABA signaling in response to water stress.
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PMID:ABA-activated SnRK2 protein kinase is required for dehydration stress signaling in Arabidopsis. 1251 44

Various cellular signaling pathways, such as phosphatidylinositol 3-kinase, calcineurin, Janus kinase 2/signal transducer and activator of transcription 3 (STAT3), and mitogen-activated protein kinase (MAPK) have been suggested to play an important role in skeletal muscle growth. Old muscle, compared with young muscle, lacks the ability to completely regrow its muscle mass after an atrophy-induced stimulus. it is hypothesized that defects and/or delays in the activation of specific cell signaling pathways of aged soleus muscle limit the potential for growth. To test this, 42 male Fischer 344 x Brown Norway rats, 30 mo old, were hindlimb immobilized for 10 days, and their muscle samples were compared with muscle samples analyzed from 3- to 4-mo-old rats in a previous report (Childs TE, Spangenburg EE, Vyas DR, and Booth FW. Am J Physiol Cell Physiol: 285: C391-C398, 2003). After 10 days, the immobilization was removed and rats were allowed to ambulate for a series of days. Alterations in the activation or deactivation status of specific signaling pathways were determined by comparing the phosphorylation (phos) and total concentration of specific signaling proteins (pan) through Western blotting with the 10-day immobilization group. Various cell signals and their respective time groups of the old rats were shown to be significantly different compared with the 10-day immobilization group. For example, peak increases during recovery from the immobilization were observed at 1) the third recovery day for calcineurin B-pan and 2) the sixth recovery day for glycogen synthase kinase-3beta-phos, p70 S6 kinase (p70S6k) -phos and -pan, calcineurin A-pan, STAT3-phos and -pan, p44 MAPK-pan, and p42 MAPK-pan. In contrast, Akt-pan, c-Jun NH2-terminal kinase-phos, and p38 MAPK-phos were observed to decrease from 10-day immobilization values to control levels. Also, Aktphos was unchanged among all groups. In a follow-up experiment in which muscle samples from both the present study and a previous study (Childs TE, Spangenburg EE, Vyas DR, and Booth FW. Am J Physiol Cell Physiol: 285: C391-C398, 2003) were reanalyzed together, the recovery-induced increase in p70S6k-phos from immobilization-atrophy was significantly attenuated in soleus muscles of the old group.
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PMID:Responsiveness of cell signaling pathways during the failed 15-day regrowth of aged skeletal muscle. 1451 1

OBJECTIVE: To elucidate the molecular mechanisms involved in hypoxic preconditioning (HPC) of neonatal rat cardiomyocytes against hypoxia/reoxygenation (H/R) injury. METHODS: Cardiomyocytes from neonatal Sprague-Dawley rats were randomly distributed into the following experimental groups: (1) HPC group: 20 min of hypoxia was performed to induce hypoxic preconditioning. Twenty four hours after HPC, cardiomyocytes were exposed to lethal hypoxia for 3 h followed by 3 h normoxia (reoxygenation). (2) Hypoxia/reoxygenation (H/R) group: cardiomyocytes were directly subjected to hypoxia (3 h) followed by reoxygenation (3 h). (3) PD98059+HPC (PD+HPC) group: cardiomyocytes were preincubated with PD98059 (a selective MEK-1/2 inhibitor, 50 mumol/l) 10 min prior to HPC. (4) BDM+HPC group: cardiomyocytes were pretreated with an activator of protein phosphatase 2,3-butanedione monoxide (BDM, 20 mmol/l) 10 min prior to HPC. (5) Control group: cardiomyocytes were incubated in cell incubator for 30 h. Viability of cardiomyocytes was assessed by MTT assay. Lactate dehydrogenase (LDH) activity in medium was determined using a LDH assay kit. Activity of p42/44 mitogen-activated protein kinases (p42/44 MAPKs) was detected using Western blotting method. SDS-PAGE mobility shift experiments were performed to determine phosphorylation of Hypoxia-inducible factor-1alpha (HIF-1alpha). RESULTS: HPC promoted survival and membrane integrity of cardiomyocytes subjected to subsequent sustained H/R. The protective effects of HPC were completely abolished either by PD98059 [a selective inhibitor of MEK-1/2 (upstream activators of p42/44 MAPKs)], or by BDM (an activator of protein phosphatase). Western blot analysis showed activated p42/44 MAPKs in whole cell extracts from hypoxic preconditioned cardiomyocytes. SDS-PAGE mobility shift experiments showed increased phophorylation level of HIF-1alpha in HPC group, and the phosphorylation can be blocked by PD98059 or BDM. CONCLUSIONS: HPC protects neonatal cardiomyocytes against H/R injury by promoting cardiomyocyte survival and membrane integrity. The protective mechanism might be attributed to upregulation of HIF-1alpha phosphorylation which may be induced by P42/44 MAPKs.
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PMID:Hypoxic preconditioning of cardiomyocytes and cardioprotection: phophorylation of HIF-1alpha induced by p42/p44 mitogen-activated protein kinases is involved. 1456 22

Leptin injection increases plasma levels of nitrites and/or nitrates, an index of nitric oxide (NO) production. Because plasma levels of NO are correlated with fat mass and because adipose tissue is the main source of leptin, it seems that adipose tissue plays a major role in NO release induced by leptin. Adipocytes express both leptin receptors and nitric oxide synthase (NOS; including the endothelial isoform, NOS III, and the inducible isoform, NOS II). In this study, we have demonstrated that physiological concentrations of leptin stimulate NOS activity in adipocytes. This effect of leptin is abolished by 1) AG490, an inhibitor of Janus tyrosine kinase 2/signal transducer and activator of transcription 3; 2) U0126, an inhibitor of mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (p42/p44 MAPK); and 3) N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89) or Rp diastereomer of adenosine 3',5'-cyclic phosphorothioate, two inhibitors of protein kinase A, but not by wortmannin, an inhibitor of phosphatidylinositol 3-kinase. Immunoblotting studies have shown that leptin fails to activate Akt but increases p42/p44 MAPK phosphorylation, an effect that is prevented by U0126 but not by H-89. Furthermore, leptin induces NOS III phosphorylation at Ser(1179) and Thr(497), but not when adipocytes are pretreated with H-89 or U0126. Finally, stimulation of adipocyte NOS activity by leptin is either unaltered when protein phosphatase 2A is inhibited by 1 nM okadaic acid or completely abolished when protein phosphatase 1 (PP1) activity is inhibited by 3 nM tautomycin, which supports a crucial role for PP1 in mediating this effect of leptin. On the whole, these experiments demonstrate that NOS activity is a novel target for leptin in adipocytes and that the leptin-induced NOS activity is at least in part the result of NOS III phosphorylations via both protein kinase A and p42/p44 MAPK activation. More generally, this study also leads to the hypothesis of NO as a potentially important factor for leptin signaling in adipocytes.
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PMID:Leptin-induced nitric oxide production in white adipocytes is mediated through PKA and MAP kinase activation. 1577 23

We present evidence that increases in intracellular calcium, induced by treatment with calcium ionophore A23187 or the endoplasmic reticulum calcium-ATPase inhibitor thapsigargin, dephosphorylated histone H3 at serine10 (histone H3-Ser10) in a dose-dependent manner in human hepatoma HepG2 cells. Inhibition of p42/44MAPK, pp90RSK, or p38MAPK did not affect the ability of A23187 to dephosphorylate histone H3-Ser10. This response is significantly blocked by okadaic acid, indicating a requirement for protein phosphatase 2A (PP2A). A23187 increased the activity of PP2A towards phosphorylated histone H3-Ser10. Furthermore, pretreatment with calphostin C, a selective protein kinase C (PKC) inhibitor, blocked A23187-dependent dephosphorylation of histone H3-Ser10, and coimmunoprecipitation analysis showed PP2A association with the PKCbetaII isoform. Unlike untreated cells, coimmunoprecipitated complex from A23187-treated cells showed greater dephosphorylation of histone H3-Ser10 in a PP2A-dependent manner. Inhibition of PP2A increased phosphorylation at Ser660 that determines calcium sensitivity and activity of PKCbetaII isoform, thus supporting a role for intracomplex regulation. Finally, chromatin immunoprecipitation assays following exposure to A23187 and okadaic acid revealed regulatory role of histone H3-Ser10 phosphorylation in selective gene induction. Altogether, our findings suggest a novel role for calcium in modulating histone H3-Ser10 phosphorylation level and led us to propose a model emphasizing PP2A activation, occurring downstream following perturbations in calcium homeostasis, as key event in dephosphorylating histone H3-Ser10 in mammalian cells.
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PMID:Increases in intracellular calcium dephosphorylate histone H3 at serine 10 in human hepatoma cells: potential role of protein phosphatase 2A-protein kinase CbetaII complex. 1588 Apr 62

Exposure of platelets to toxins (calyculin A or okadaic acid) that inhibit protein serine/threonine phosphatases types 1 and 2A, at concentrations that block aggregatory and secretory responses, results in the phosphorylation of several platelet proteins including integrin beta(3). Since protein phosphorylation represents a balance between kinase and phosphatase activities, this increase in phosphorylation reflects either the removal of phosphatases that oppose constitutively active kinases known to reside in the platelet (e.g., casein kinase 2) or the activation of endogenous kinases. In this study, we demonstrate that the addition of calyculin A promotes the activation of several endogenous platelet protein kinases, including p42/44(mapk), p38(mapk), Akt/PKB, and LKB1. Using a pharmacologic approach, we assessed whether inhibition of these and other enzymes block phosphorylation of beta(3). Inhibitors of p38(mapk), casein kinase, AMP kinase, protein kinase C, and calcium-calmodulin-dependent kinases did not block phosphorylation of beta(3) on thr(753). In contrast, 5'-iodotubercidin, at 50 muM, blocks beta(3) phosphorylation without affecting the efficacy of calyculin A to inhibit platelet aggregation and spreading. These data dissociate threonine phosphorylation of beta(3) molecules and inhibition of platelet responses by protein phosphatase inhibitors.
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PMID:Threonine phosphorylation of integrin beta3 in calyculin A-treated platelets is selectively sensitive to 5'-iodotubercidin. 1705 67


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