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:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have recently isolated the cDNA for the murine homologue of the stress-inducible phosphoprotein STI1 (also known as IEF SSP 3521 or p60). STI1 was previously shown to be 2-fold up-regulated in MRC-5 fibroblasts upon viral transformation and to exist in a macromolecular complex with heat shock proteins of the HSP 70 and 90 families. By peptide-sequencing we have identified the two heat shock proteins that bind to murine STI1 (mSTI1) as HSC 70 and HSP 84/86. We describe two separate binding regions within mSTI1 for the two heat shock proteins. In the presence of cell extracts, the N-terminal region of mSTI1 binds preferentially to HSC 70, whereas the C-terminal portion of the molecule promotes the binding of HSP 84/86. Heat treatment caused a strong induction of mSTI1 message without affecting the steady-state level of the protein significantly. In addition, heat treatment led to changes in the isoform-composition of mSTI1. pp70(s6k), pp90(rsk), and mitogen-activated protein kinase-activated protein kinase 2 were tested as possible STI1 kinases in vitro using recombinant mSTI1 as a substrate: only pp90(rsk) was able to phosphorylate recombinant mSTI1. In vitro kinase assays using casein kinase II suggest serine 189 to be a likely phosphorylation site in mSTI1.
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PMID:Stress-inducible, murine protein mSTI1. Characterization of binding domains for heat shock proteins and in vitro phosphorylation by different kinases. 899 75

This laboratory reported previously that overexpressed heat shock protein 70 kDa (HSP-70) inhibited the activation of its transcriptional factor, HSF1. We had conducted experiments to understand the mechanisms whereby HSP-70 down-regulated the activation of HSF1. Genetically overexpressed HSP-70 had no effects on the HSF1 level in cytosol, but significantly inhibited phosphorylation of HSF1 in the nucleus. Transfection of cells with HSF1 cDNA resulted in increases in the unphosphorylated, but not phosphorylated, HSF1 levels in both the cytosol and nucleus. Because serine phosphorylation of various proteins was reduced in HSP-70 cDNA-transfected cells, we measured the activity of enzymes involved in serine phosphorylation. Overexpressed HSP-70 significantly inhibited the enzymatic activities of protein kinase A (PKA by 73 and 62% in the cytosol and membrane-bound fraction, respectively) and protein kinase C (PKC by 61% in membrane-bound fraction), whereas it activated that of protein phosphatase (PP by 33 and 86% in the cytosol and the membrane-bound fraction, respectively). Forskolin (a PKA stimulator), PMA (a PKC stimulator), and okadaic acid (an inhibitor of PP) were used to investigate whether HSP-70-induced changes in PKA, PKC, and PP were responsible for the HSF1 dephosphorylation. Forskolin did not change nuclear HSF1 phosphorylation, suggesting that decreases in PKA activity in HSP-70 overexpressing cells is not associated with HSF1 phosphorylation. PMA and okadaic acid induced an increase in HSF1 phosphorylation in both vector- and HSP-70 cDNA-transfected cells, although levels of phosphorylated HSF1 in HSP-70 cDNA-transfected cells were lower than those in vector-transfected cells. The PMA-induced increase in HSF1 phosphorylation in HSP-70 cDNA-transfected cells was blocked by pretreatment with staurosporine, a PKC inhibitor. These results suggest that overexpression of HSP-70 inhibits phosphorylation of HSF1 at serine residues by activating PP and inhibiting PKC activity.
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PMID:Overexpression of HSP-70 inhibits the phosphorylation of HSF1 by activating protein phosphatase and inhibiting protein kinase C activity. 953 17

Small heat-shock proteins (sHSPs) are widely expressed 25-28 kDa proteins whose functions are dynamically regulated by phosphorylation. While recent efforts have clearly delineated a stress-responsive p38 mitogen-activated protein-kinase (MAPK)-dependent kinase pathway culminating in activation of the heat-shock (HSP)-kinases, mitogen-activated protein-kinase-activated protein kinase-2 and -3, not all sHSP phosphorylation events can be explained by the p38 MAPK-dependent pathway. The contribution of protein kinase C (PKC) to sHSP phosphorylation was suggested by early studies but later questioned on the basis of the reported poor ability of purified PKC to phosphorylate sHSP in vitro. The current study re-evaluates the role of PKC in sHSP phosphorylation in the light of the isoform complexity of the PKC family. We evaluated the sHSP phosphorylation status in rat corpora lutea obtained from two stages of pregnancy, mid-pregnancy and late-pregnancy, which express different levels of the novel PKC isoform, PKC-delta. Two-dimensional Western blot analysis showed that HSP-27 was more highly phosphorylated in vivo in corpora lutea of late pregnancy, corresponding to the developmental stage in which PKC-delta is abundant and active. Late-pregnant luteal extracts contained a lipid-sensitive HSP-kinase activity which exactly co-purified with PKC-delta using hydroxyapatite and S-Sepharose column chromatography. To determine whether there might be preferential phosphorylation of sHSP by a particular PKC isoform, purified recombinant PKC isoforms corresponding to those PKC isoforms detected in rat corpora lutea were evaluated for HSP-kinase activity in vitro. Recombinant PKC-delta effectively catalysed the phosphorylation of sHSP in vitro, and PKC-alpha was 30-50% as effective as an HSP-kinase; other PKCs tested (beta1, beta2, epsilon and zeta) were poor HSP-kinases. These results show that select PKC family members can function as direct HSP-kinases in vitro. Moreover, the observation of enhanced luteal HSP-27 phosphorylation in vivo, in late pregnancy, when PKC-delta is abundant and active, suggests that select PKC family members contribute to sHSP phosphorylation events in vivo.
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PMID:Heat-shock protein-25/27 phosphorylation by the delta isoform of protein kinase C. 962 Aug 73

This study investigates the possibility that FSH activates the p38 mitogen-activated protein kinase (MAPK) pathway in immature granulosa cells (GC). FSH induced the phosphorylation (activation) of p38 MAPK as evaluated by immunoprecipitation and by phosphorylation-specific immunoblotting. FSH-induced phosphorylation of p38 MAPK was blocked by pretreatment with the protein kinase A (PKA) inhibitor H89 and mimicked by the cAMP generating agonist forskolin, indicating that FSH-induced cAMP production and PKA activation are necessary and sufficient for the activation of p38 MAPK in GC. The small heat shock protein HSP-27 comprises a downstream phosphorylation target for the p38 MAPK pathway. FSH-induced phosphorylation of HSP-27 was blocked by pretreatment with the p38 MAPK inhibitor SB 203580, indicating that p38 MAPK activation is necessary for FSH-induced HSP-27 phosphorylation. FSH-induced GC rounding/aggregation was blocked by pretreatment with SB 203580 indicating that p38 MAPK activation is necessary for FSH-induced GC cell shape change. The results of these experiments show that the p38 MAPK pathway is activated in GC in response to FSH in a cAMP/PKA-dependent manner, and that p38 MAPK activity is required for FSH-induced HSP-27 phosphorylation as well as rounding/aggregation in GC.
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PMID:Follicle stimulating hormone (FSH) activates the p38 mitogen-activated protein kinase pathway, inducing small heat shock protein phosphorylation and cell rounding in immature rat ovarian granulosa cells. 964 11

Nitric oxide (NO) exerts contrasting effects on apoptosis, depending on its concentration, flux and cell type. In some situations, NO activates the transduction pathways leading to apoptosis, whereas in other cases NO protects cells against spontaneous or induced apoptosis. The redox state of the cells appears to be a crucial parameter for the determination of the ultimate action of NO on cell multiplication and survival. Apoptosis is mostly associated with the delivery of NO by chemical donors and with myelomonocytic cells, whereas antiapoptotic effects seem to be related to the endogenous production of NO by NO synthases and is observed more frequently in cells of the B lymphocyte lineage. Pro-apoptotic effects are often observed when NO reacts with superoxide to produce the highly toxic peroxynitrite. Through the induction of damages to DNA, NO stimulates the expression of enzymes and transcription factors involved in DNA repair and modulation of apoptosis, such as the tumor suppressor p53. The latter molecule transactivates the expression of pro-apoptotic genes, such as bax, and that of the cyclin-dependent kinase inhibitor p21, whereas it down-regulates the expression of the anti-apoptotic protein bcl-2. On the other hand, NO inactivates caspases through oxidation and S-nitrosylation of the active cystein, providing an efficient means to block apoptosis. Other protective effects of NO on apoptosis rely on the stimulation of cGMP-dependent protein kinase (PKG), modulation of the members of the bcl-2/bax family that control the mitochondrial pore transition permeability, induction of the heat shock protein HSP 70 and interaction with the ceramide pathway. A defect in the apoptotic process contributes to the accumulation of tumoral cells in leukemia, notably in B-CLL. A better knowledge of the targets of NO would provide efficient means to control cell apoptosis, and hence would possibly lead to the development of new therapeutic approaches for diseases where an alteration of apoptosis is involved.
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PMID:Mechanisms involved in the pro- and anti-apoptotic role of NO in human leukemia. 1099 17

The current study investigates the activation in vivo and regulation of the expression of components of the p38 mitogen-activated protein kinase (MAPK) pathway during gonadotropin-induced formation and development of the rat corpus luteum, employing a sequential PMSG/human CG (hCG) treatment paradigm. We postulated that the p38 MAPK pathway could serve to promote phosphorylation of key substrates during luteal maturation, since maturing luteal cells, thought to be cAMP-nonresponsive, nevertheless maintain critical phosphoproteins. Both p38 MAPK and its upstream activator MAPK kinase-6 (MKK6) were found to be chronically activated during the luteal maturation phase, with activation detected by 24 h post hCG and maintained through 4 days post hCG. The p38 MAPK downstream protein kinase target termed MAPK-activated protein kinase-3 (MAPKAPK-3) was newly induced at both mRNA and protein levels during luteal formation and maturation, while mRNA and protein expression of the closely related MAPKAPK-2 diminished. Two potential substrates for MAPKAPKs, the small heat shock protein HSP-27 and the cAMP regulatory element binding protein CREB, were monitored in vivo for phosphorylation. HSP-27 phosphorylation was not modulated during luteal maturation. In contrast, we observed sustained luteal-phase CREB phosphorylation in vivo, consistent with upstream MKK6/p38 MAPK activation and MAPKAPK-3 induction. MAPKAPK-3-specific immune complex kinase assays provided direct evidence that MAPKAPK-3 was in an activated state during luteal maturation in vivo. Cellular inhibitor studies indicated that an intact p38 MAPK path was required for CREB phosphorylation in a cellular model of luteinization, as treatment of luteinized granulosa cells with the p38 MAPK inhibitor SB 203580 strongly inhibited CREB phosphorylation. Transient transfection studies provided direct evidence that MAPKAPK-3 was capable of signaling to activate CREB transcriptional activity, as assessed by means of GAL4-CREB fusion protein construct coexpressed with GAL4-luciferase reporter construct. Introduction of wild-type, but not kinase-dead mutant, MAPKAPK-3 cDNA, into a mouse ovarian cell line stimulated GAL4-CREB- dependent transcriptional activity approximately 3-fold. Thus MAPKAPK-3 is indeed uniquely poised to support luteal maturation through the phosphorylation and activation of the nuclear transcription factor CREB.
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PMID:Developmental regulation of mitogen-activated protein kinase-activated kinases-2 and -3 (MAPKAPK-2/-3) in vivo during corpus luteum formation in the rat. 1132 54

The nitric oxide (NO) synthase inhibitor N(omega)-nitro-L-arginine (L-NNA) inhibits heat stress (HS)-induced NO production and the inducible 70-kDa heat shock protein (HSP-70i) in many rodent organs. We used human intestinal epithelial T84 cells to characterize the inhibitory effect of L-NNA on HS-induced HSP-70i expression. Intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured using fura-2, and protein kinase C (PKC), and PKA activities were determined. HS increased HSP-70i mRNA and protein in T84 cells exposed to 45 degrees C for 10 min and allowed to recover for 6 h. L-NNA treatment for 1 h before HS inhibited the induction of HSP-70i mRNA and protein, with an IC(50) of 0.0471 +/- 0.0007 microM. Because the HS-induced increase in HSP-70i mRNA and protein is Ca(2+) dependent, we measured [Ca(2+)](i) after treating cells with L-NNA. L-NNA at 100 microM significantly decreased resting [Ca(2+)](i). Likewise, treatment with 1 microM GF-109203X or H-89 (inhibitors of PKC and PKA, respectively) for 30 min also significantly decreased [Ca(2+)](i) and inhibited HS-induced increase in HSP-70i. GF-109203X- or H-89-treated cells failed to respond to L-NNA by further decreasing [Ca(2+)](i) and HSP-70i. L-NNA effectively blocked heat shock factor-1 (HSF1) translocation from the cytosol to the nucleus, a process requiring PKC phosphorylation. These results suggest that L-NNA inhibits HSP-70i by reducing [Ca(2+)](i) and decreasing PKC and PKA activity, thereby blocking HSF1 translocation from the cytosol to the nucleus.
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PMID:N(omega)-nitro-L-arginine inhibits inducible HSP-70 via Ca(2+), PKC, and PKA in human intestinal epithelial T84 cells. 1184 91

Geldanamycin (GA), herbimycin A and radicicol bind heat-shock protein-90 (Hsp90) and destabilize its client proteins including v-Src, Bcr-Abl, Raf-1, ErbB2, some growth factor receptors and steroid receptors. Thus, Hsp90-active agents induce ubiquitination and proteasomal degradation of numerous oncoproteins. Depending on the cellular context, HSP90-active agents cause growth arrest, differentiation and apoptosis, or can prevent apoptosis. HSP-active agents are undergoing clinical trials. Like targets of most chemotherapeutics, Hsp90 is not a cancer-specific protein. By attacking a nonspecific target, HSP-90-active compounds still may preferentially kill certain tumor cells. How can this be achieved? How can therapeutic potentials be exploited? This article starts the discussion.
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PMID:Hsp-90-associated oncoproteins: multiple targets of geldanamycin and its analogs. 1196 Mar 22

One of the stress conditions that yeast may encounter is the presence of acetaldehyde. In a previous study we identified that, in response to this stress, several HSP genes are induced that are also involved in the response to other forms of stress. Aldehyde dehydrogenases (ALDH) play an important role in yeast acetaldehyde metabolism (e.g. when cells are growing in ethanol). In this work we analyse the expression of the genes encoding these enzymes (ALD) and also the corresponding enzymatic activities under several growth conditions. We investigate three kinds of yeast strains: laboratory strains, strains involved in the alcoholic fermentation stage of wine production and flor yeasts (responsible for the biological ageing of sherry wines). The latter are very important to consider because they grow in media containing high ethanol concentrations, and produce important amounts of acetaldehyde. Under several growth conditions, further addition of acetaldehyde or ethanol in flor yeasts induced the expression of some ALD genes and led to an increase in ALDH activity. This result is consistent with their need to obtain energy from ethanol during biological ageing processes. Our data also suggest that post-transcriptional and/or post-translational mechanisms are involved in regulating the activity of these enzymes. Finally, analyses indicate that the Msn2/4p and Hsf1p transcription factors are necessary for HSP26, ALD2/3 and ALD4 gene expression under acetaldehyde stress, while PKA represses the expression of these genes.
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PMID:Response to acetaldehyde stress in the yeast Saccharomyces cerevisiae involves a strain-dependent regulation of several ALD genes and is mediated by the general stress response pathway. 1279 36

Exercise training could potentially exert beneficial effects on the signaling events associated with cardiac cell apoptosis. Spontaneously hypertensive rats (SHR) were trained 5 days/week on a treadmill (18 m/min for 120 min/day) between the ages of 4 weeks and 1 week, corresponding to the hypertensive accelerating phase. The effect of exercise training on the expression of anti-apoptotic proteins HSP-72, Bcl-2 and protein kinase B (PKB), and the apoptotic proteins Bax and glycogen synthase kinase-3 (GSK-3) was examined. Exercise had a significant acute lowering effect on blood pressure, but this decrease did not attenuate the progressive increase in blood pressure. In the left ventricles of exercised SHR, PKB phosphorylation of both Ser473 and Thr308 residues was significantly increased by 166% and 120%, respectively, compared to sedentary SHR. PKB phosphorylation significantly correlated with GSK-3beta phosphorylation. HSP-72 and Bcl-2 protein expression were increased in the left ventricle of exercised SHR, and associated with the concomitant increased expression of the protein Bax. Thus, the Bcl-2/Bax ratio was not changed by exercise training, suggesting that the anti-apoptotic mechanism was effective in compensating the increase in the expression of the pro-apoptotic protein Bax in the myocardium of the SHR.
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PMID:Exercise training enhanced the expression of myocardial proteins related to cell protection in spontaneously hypertensive rats. 1529 Mar


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