Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.11 (AMPK)
 12,425 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have examined the effects of cyclosporine A (CsA) on a number of CTL effector functions. CsA partially inhibited the CTL-mediated lysis of Ag-bearing target cells. Both target cell- and anti-TCR mAb-induced granule exocytosis were markedly inhibited by CsA. In addition, marked inhibition of PMA and calcium ionophore (A23187) induced granule exocytosis was produced by CsA suggesting that the inhibitory effects of CsA on granule exocytosis involve biochemical events after protein kinase C activation and increases in intracellular free Ca2+. CsA had no inhibitory effects on TCR-mediated phosphatidylinositol metabolism. The inhibitory effects of CsA were not mediated by the cAMP-dependent protein kinase inhibitory pathway and no effect of CsA on the Ca2+-induced binding of calmodulin to calmodulin-binding proteins could be demonstrated. CsA was also a potent inhibitor of IgE receptor-mediated exocytosis in rat basophil leukemia cells. CsA had no effect on receptor-mediated phosphatidylinositol hydrolysis; 400 ng/ml CsA resulted in a 90% inhibition of serotonin release but had no effect on phosphatidylinositol hydrolysis. These results indicate that CsA may inhibit some common event in Ca2+-dependent secretory cells. Taken together, these results suggest that CsA does not inhibit signal transduction but rather interferes with the biochemical events in the later stages of Ca2+-dependent reactions that follow the binding of calmodulin to cytoskeletal or cytoplasmic calmodulin binding proteins.
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PMID:Biochemical characterization of the inhibitory effect of CsA on cytolytic T lymphocyte effector functions. 254 Dec 1

Bovine adrenal fasciculata cells, exposed to either ACTH or AII, synthesize glucocorticoids at an enhanced rate. It is generally accepted that the signaling pathways triggered by these two peptides are not identical. ACTH presumably acts via a cAMP-dependent protein kinase (PKA) and AII, via a calcium-dependent protein kinase. We have found that either peptide hormone stimulates synthesis of a mitochondrial phosphoprotein pp37, leading to accumulation of its proteolytically processed products pp30 and pp29. On the basis of a number of criteria, this 37 kDa protein is the bovine homolog of the 37 kDa protein that we have characterized in rodent steroidogenic tissue (Epstein L. F. and Orme-Johnson N. R.: J. Biol. Chem 266 (1991) 19,739-19,745). Further, bovine pp37 is phosphorylated when PKA or protein kinase C (PKC) is activated directly by (Bu)2 cAMP or PMA, respectively. These studies indicate that either pp37 is a common substrate for PKA and PKC in these cells or there is a common downstream kinase, which is activated by exposure to either ACTH or AII. Rat adrenal glomerulosa cells, exposed to either ACTH or AII, show an enhanced rate of mineralocorticoid synthesis. As for bovine fasciculata cells, it is thought that the signaling pathway triggered by ACTH differs from that triggered by AII. As we found for bovine fasciculata, pp37 is phosphorylated when the rat cells are exposed to either peptide hormone. However, in contrast to the finding for bovine fasciculata, while exposure of the rat glomerulosa cells to (Bu)2cAMP does cause the synthesis of pp37, exposure of the cells to PMA does not. Taken together, these findings provide further evidence that the subcellular signaling events, triggered by the action of AII on bovine adrenal fasciculata and rat adrenal glomerulosa cells, differ. Further, the fact, that pp37 is phosphorylated only when the rate of steroidogenesis is enhanced, reaffirms its potential involvement in the signaling pathway that causes stimulation of steroid hormone biosynthesis.
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PMID:Comparison of protein phosphorylation patterns produced in adrenal cells by activation of cAMP-dependent protein kinase and Ca-dependent protein kinase. 762 24

We have previously demonstrated that activation of cAMP-dependent protein kinase (cAK) type I (cAKI, RI alpha 2-C beta 2) mediates the inhibitory effects of cAMP on T-cell replication induced through the TCR/CD3 complex. In the present study we have investigated the effect of cAMP on T-cell DNA synthesis, tyrosine phosphorylation of a 100 kDa protein (pp100) and IL2 mRNA expression, induced through stimulation of the TCR/CD3- and/or the CD28 molecules. Our results demonstrate that tyrosine phosphorylation of pp100 stimulated by anti-CD3 is inhibited by cAMP both in the presence and absence of the phorbol ester PMA, and reflects the changes seen in IL2 mRNA expression and T-cell replication. Combined stimulation with anti-CD3 and anti-CD28, which gives a synergistic response in T-cell replication, gave pp100 phosphorylation and IL2 mRNA expression sensitive to cAMP-dependent inhibition. When PMA was added in addition to anti-CD3 and anti-CD28, the inhibitory effect of cAMP on both T-cell replication and pp100 phosphorylation was completely abolished. The fact that pp100 phosphorylation in response to TCR/CD3-, CD28- and PMA stimulation and cAMP mediated inhibition are identical to the effects of the same stimuli on T-cell proliferation, makes this protein an interesting candidate in downstream signalling from these receptors. In addition, our results are compatible with a model where cAMP, through activation of cAKI, eliminates both the PTK and PKC activating capability of the T-cell receptor at a site(s) proximal to PKC activation. Furthermore, the CD28 molecule which activates PTKs, enters the PTK cascade at a point distal to the target(s) for cAKI action. Therefore, during CD28 signalling PKC activation can be achieved either by TCR/CD3 stimulation (inhibited by cAMP), or directly by PMA (not inhibited by cAMP).
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PMID:Cyclic AMP sensitive signalling by the CD28 marker requires concomitant stimulation by the T-cell antigen receptor (TCR/CD3) complex. 804 42

Multiple processes lead to neuronal death after ischemia, but the generation of nitric oxide (NO) is a key component in this cascade of events. The mechanisms that regulate the extent of neuronal degeneration during anoxia and NO toxicity are multifactorial. Neuronal death may be modulated by the activity of signal transduction systems that influence the toxicity of NO or its metabolic products such as cGMP. The enzyme responsible for the production of NO, nitric oxide synthase (NOS), is phosphorylated by protein kinase C (PKC), the cAMP-dependent protein kinase (PKA), and the calcium/calmodulin-dependent protein kinase II (CaM-II). We examined in primary cultured hippocampal neurons whether the protein kinases PKC, PKA, CaM-II, and cGMP-dependent protein kinase modified the toxic effects of anoxia and NO. Down-regulation of PKC activity with PMA (1 microM) increased hippocampal neuronal survival during anoxia and NO exposure from approximately 22% to 88%. Inhibitors of PKC activity (H-7, H-8, sphingosine, and staurosporine) also were neuroprotective. Down-regulation of PKC activity increased survival during anoxia even in the presence of the NOS inhibitor, N omega-methyl-L-arginine. Thus, although down-regulation of PKC activity may increase neuronal survival by decreasing NOS activity, it also is likely that PKC contributes to ischemic neuronal death by mechanisms that are independent of NOS. Inhibition of the cGMP-dependent protein kinase activity, but not the activity of the CaM-II also was neuroprotective during NO administration. In contrast to the protective effects of inhibition of PKC and the cGMP-dependent protein kinase, activation rather than inhibition of PKA increased hippocampal neuronal survival during NO exposure. These results indicate that neuronal survival during anoxia and NO exposure is linked to the modulation of PKC, PKA, and cGMP-dependent protein kinase activity but is not dependent on the CaM-II pathway. Understanding the involvement of PKC, PKA, and the cGMP-dependent protein kinase in modulating the effect of neuronal death during ischemia and NO toxicity may help in directing future therapeutic modalities for cerebrovascular disease.
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PMID:Protein kinases modulate the sensitivity of hippocampal neurons to nitric oxide toxicity and anoxia. 823 Mar 23

Embryonic quail neural crest cells migrate towards the negative pole of an imposed dc electric field as small as 7 mV/mm (0.4 mV per average cell length). The involvement of protein kinases in the mechanism utilized by these cells to detect and respond to such imposed fields was tested through the use of several kinase inhibitors. Evidence for the involvement of protein kinase C (PKC) included: (1) inhibition of the directed motility by 1 microM sphingosine that was reversed by the addition of the phorbol ester, PMA; (2) stimulation of a faster response to the imposed field by PMA; and (3) inhibition of the directed translocation by 5 microM H-7. However, another PKC inhibitor, staurosporine, did not inhibit the directed translocation (1 nM-1 microM). We also found evidence for the involvement of either cAMP- or cGMP-dependent protein kinase. The galvanotactic response was partially inhibited by the addition of 10 microM H-9 and the response was enhanced in the presence of the phosphodiesterase inhibitor, IBMX. However, the adenylate cyclase stimulant, forskolin, had no significant influence on the directed motility, although it reduced the average cell velocity. While these experiments suggest that cAMP- or cGMP-dependent protein kinase or PKC may be involved in the galvanotaxis response, two other protein kinases appeared not to be required. The myosin light chain kinase inhibitor, ML-7, had no effect on the directed motility in an imposed field, so myosin light chain kinase may not be required for galvanotaxis. Similarly, 5 microM W-7 had no significant effect on the directed translocation, suggesting that calmodulin-dependent protein kinase is not involved. Interestingly, the continuous activity of a protein kinase is apparently not required for the directed translocation response. The addition of the PKC and cAMP-dependent protein kinase inhibitor, H-7, after the cells had been exposed to the field for 1 hour, had no effect on the subsequent directed translocation. Thus, for these inhibitors to block the directed translocation, they must be present at the same time as the initial field application. This implies that an integral step in the cellular response mechanism for galvanotaxis involves the stimulation of a protein kinase whose effect is long lasting.
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PMID:Protein kinases are required for embryonic neural crest cell galvanotaxis. 831 67

In osteoblastic UMR-106 cells, 10(-7) M human (h) PTH-related peptide (PTHrP)-(1-34) significantly induced the formation of total inositol phosphates to the same degree as 10(-7) M hPTH-(1-34), confirming that in addition to cAMP-dependent protein kinase (PKA), PTHrP possesses another signal transduction system, calcium/protein kinase C (Ca/PKC). Experiments were therefore performed to characterize the cross talk of these dual-signal transduction systems and its participation in the PTHrP-induced homologous desensitization of cAMP and cytosolic calcium (Cai) response in osteoblasts. Preincubation with 10(-7) M hPTHrP-(1-34) caused homologous desensitization, resulting in a remarkable decrease in cAMP accumulation in response to further exposure to PTHrP. This effect was significant after 2 h pretreament and reached a maximum at 6 h. Pretreatment with the PKC-activating phorbol ester phorbol 12-myristate-13-acetate (PMA, 10(-6) M) for 30 minutes and 6 h caused a significant increase and decrease in cAMP responsiveness to PTHrP, respectively. Pretreatment with calcium ionophores (A23187 or ionomycin, 10(-6) M), not for 30 minutes but for 6 h, caused a significant decrease in cAMP responsiveness to PTHrP. H-7 (an inhibitor of PKC, 50 microM) significantly blocked not only PMA- but also PTHrP-induced desensitization of the cAMP response. PTHrP caused the complete homologous desensitization of an increase in Cai within 30 minutes. Pretreatment with dibutyryl-cAMP (10(-4) M) for 30 minutes caused significant inhibition of the PTHrP-induced increase in Cai, and pretreatment with Sp-cAMPS (10(-4) M), a direct activator of PKA, for 30 minutes completely blocked the PTHrP-induced increase in Cai.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Interaction of parathyroid hormone-related peptide-responsive dual signal transduction systems in osteoblastic osteosarcoma cells: role in PTHrP-induced homologous desensitization. 838 30

Activation of protein kinase C (PKC) by phorbol ester (PMA), or by diacylglycerol analogue (OAG) treatment of NIH 3T3 cells resulted in the rapid (within 2-5 min) stimulation (approx. 2-fold) of sodium-dependent phosphate (Pi) transport. Conversely, preincubation of these cells with forskolin and cholera toxin, or incubation with 8-bromo-cAMP, to activate cAMP-dependent protein kinase (PKA), resulted in a decrease in Na+/Pi transport. Activation of either PKC or PKA did not change the Vmax of Pi uptake. However, activation of PKC did result in an increase, while activation of PKA caused a decrease, in the affinity for Pi. These results indicate that there is differential regulation of Na+/Pi uptake in NIH 3T3 cells by activators of PKC (stimulated) and PKA (inhibited) as a consequence of changes in the affinity of the transporter for Pi.
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PMID:Differential effects of activation of protein kinase C and cyclic-AMP-dependent protein kinase on sodium-dependent phosphate uptake in NIH 3T3 cells. 847 34

A specific antiserum against the human m3-muscarinic receptor subtype was made by subcloning a variant region of the third intracellular loop of the m3-receptor (Ser345-Leu463) into a bacterial expression plasmid that produced a fusion protein with glutathione S-transferase. In immunoblot studies this anti-serum identified the human m3-receptor expressed in transfected Chinese hamster ovary (CHO) cells (CHO-m3 cells, 1343 fmol/mg protein) as a diffuse band at approximately 97-110 kDa. In vivo labeling of the ATP pool in CHO-m3 cells with [32P]orthophosphate followed by immunoprecipitation of solubilized m3-receptors revealed that the unstimulated receptor existed in a phosphorylated form. Incubation of CHO-m3 cells with the cholinergic agonist carbachol (1 mM) increased the phosphorylated state of the receptor dramatically, primarily at serine. The time course for agonist-dependent phosphorylation was very rapid occurring within seconds of agonist addition and was maintained for at least 30 min. The muscarinic antagonist atropine (10 microM) inhibited agonist-stimulated phosphorylation. Neither forskolin (10 microM) nor the calcium ionophore, ionomycin (1 microM), had any effect on the state of phosphorylation of the m3-receptor, eliminating a role for cAMP-dependent protein kinase and Ca2+/calmodulin-dependent protein kinase in the agonist-dependent phosphorylation of m3-receptors. 4 beta-Phorbol 12 beta-myristate 13 alpha-acetate (100 nM) did increase m3-receptor phosphorylation, an effect that was inhibited by the selective protein kinase C inhibitor RO-318220 (10 microM). However, agonist-stimulated m3-receptor phosphorylation was not inhibited by RO-318220 indicating that protein kinase C was not involved in agonist-induced m3-receptor phosphorylation. In conclusion the phosphorylation of m3-receptors, in vivo, was increased following the application of muscarinic agonist or PMA. The response to agonist was mediated via a kinase distinct from protein kinase C, protein kinase A and Ca2+/calmodulin dependent protein kinase, whereas the effect of 4 beta-phorbol 12 beta-myristate 13 alpha-acetate was mediated by protein kinase C.
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PMID:Rapid agonist-mediated phosphorylation of m3-muscarinic receptors revealed by immunoprecipitation. 848 62

Several lines of evidence have previously indicated that estrogen inhibits PTH-induced bone resorption in vivo and in vitro. However, its mechanism remains unknown. Therefore, the present study was performed to investigate the effect of estrogen on PTH-stimulated osteoclast-like cell formation and clarify its mechanism. 17 beta-estradiol (17 beta-E2) significantly antagonized osteoclast-like cell formation stimulated by 10(-8) M human (h) PTH-(1-34) as well as 10(-8) M hPTH-related peptide (PTHrP)-(1-34)in osteoblast-containing mouse bone cell cultures. The conditioned medium derived from osteoblastic SaOS-2 cells or MC3T3-E1 cells pretreated with both PTH-(1-34) (10(-8)M) and 17 beta-E2(10(-8)M) stimulated osteoclast-like cell formation from hemopoietic blast cells more weakly than conditioned medium from cells pretreated with PTH-(1-34) alone. Moreover, 10(-8) M 17 beta-E2 significantly blocked the formation of osteoclast-like cells stimulated by 10(-8) M hPTH-(1-34) in spleen cell cultures derived from 5-fluorouracil-pretreated mice. On the other hand, 10(-8) M 17 beta-E2 significantly inhibited osteoclast-like cell formation stimulated by dbcAMP (10(-4)M) and Sp-cAMPS (10(-4)M), as well as forskolin (10(-5)M) in mouse bone cell cultures. In contrast, 10(-8)M 17 beta-E2 did not affect PMA (10(-7)M)-, A23187 (10(-7)M)-, or BAYK-8644 (5 x 10(-6) M)-stimulated osteoclast-like cell formation. In conclusion, the present study demonstrated that estrogen inhibits PTH-stimulated osteoclast-like cell formation by directly acting on hemopoietic blast cells as well as by indirectly acting on them via osteoblasts. The inhibitory effects of estrogen on PTH-stimulated osteoclast-like cell formation seemed to be mediated through blocking the cAMP-dependent protein kinase pathway but not by blocking calcium/protein kinase C.
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PMID:Estrogen blocks parathyroid hormone (PTH)-stimulated osteoclast-like cell formation by selectively affecting PTH-responsive cyclic adenosine monophosphate pathway. 864 Nov 68

Eosinophilia is a uniquely specific phenomenon regulated by interleukin-5 (IL-5), suggesting specific control for IL-5 gene expression. Using a transient-transfection reporter assay and DNA mobility-shift experiments in EL4 mouse lymphoma cells, reporter expression and binding of transcription factors to the conserved lymphokine element 0 (CLE0) in the mouse (mIL-5) promoter was investigated. Activation of the IL-5 promoter required costimulation of T cells with phorbol ester (phorbol 12-myristate 13-acetate [PMA]) and cyclic adenosine 3',5'-monophosphate (cAMP), but was blocked by the immunosuppressive drug, cyclosporin A (CsA). Binding to CLE0 was induced under conditions optimal for IL-5 transcription but was not blocked by CsA. CD28-induced signals could partly substitute for cAMP. However, the effects of cAMP, but not of CD28, were sensitive to the cAMP-dependent protein kinase inhibitor, H89, suggesting that CD28 does not involve a cAMP mechanism. It therefore appears that IL-5 expression can be induced by at least two distinct stimulatory pathways. Although CLE0 contains sequences similar to AP-1 and NF-AT, only the AP-1 moiety of the CLE0 element could be demonstrated to have inducible binding. Experiments with antisera to the AP-1 family of transcription factors indicated that c-fos and JunB bind to the IL-5 CLE0 in activated lymphoma cells. The role of the NF-AT-like element was less clear. A constitutively expressed protein showed a weak band that was inhibited by mIL-2 NF-AT competitor sequences. However, this protein did not react with an anti-NF-ATp antiserum. On the other hand, transcription was partially inhibited by an oligonucleotide containing the intact NF-AT-like element from CLE0, suggesting that the element is important for optimal transcription, but the nature of the protein binding to it remains unknown. The fact that these factors are induced in a subclone of EL4 that does not express IL-5 and bind to a number of other cytokine gene promoters suggests that although binding to CLE0 appears to be necessary for IL-5 transcription, other factors must control the specific expression of the gene.
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PMID:Two pathways can activate the interleukin-5 gene and induce binding to the conserved lymphokine element 0. 870 76


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