Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.17 (CaMKII)
 4,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ca2+/calmodulin-dependent protein kinase III (Ca2+/CaM kinase III) phosphorylates a protein of Mr = 100,000 (the 100-kDa protein), a major substrate for Ca2+/CaM-dependent protein phosphorylation found in many mammalian tissues and cell lines (Nairn, A.C., Baghat, B., and Palfrey, H.C. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 7939-7943). Treatment of PC12 cells with nerve growth factor (NGF) or forskolin resulted in a decrease in the depolarization-dependent phosphorylation of the 100-kDa protein in intact cells and in a decrease in the Ca2+/CaM-dependent phosphorylation of the 100-kDa protein in cytosolic extracts. In experiments using cytosolic extracts, the initial effect of NGF on the phosphorylation of the 100-kDa protein was observed in less than 1 h, was maximal (70% decrease) after 12 h, and began to recover after 24 h. The effect of forskolin was more rapid and the maximal effect was greater (90-95% decrease). Decreased Ca2+/CaM kinase III activity was also found in PC12 cells treated with epidermal growth factor, 2-chloroadenosine plus isobutylmethylxanthine, or dibutyryl cAMP. The effect of forskolin did not reverse unless it was removed. Cycloheximide blocked the recovery of Ca2+/CaM kinase III activity observed following the removal of forskolin but did not affect the ability of forskolin to reduce kinase activity. Short-term treatment with phorbol ester had little effect on Ca2+/CaM kinase III activity; long-term treatment with phorbol ester, which results in the disappearance of enzymatically detectable protein kinase C, had no effect on the ability of NGF or 2-chloroadenosine to reduce Ca2+/CaM kinase III activity. The level of the 100-kDa protein as determined by immunological techniques was not changed by any treatment. These results suggested that the effect of treatment of PC12 cells with NGF or forskolin was to reduce the level of Ca2+/CaM kinase III per se.
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PMID:Nerve growth factor treatment or cAMP elevation reduces Ca2+/calmodulin-dependent protein kinase III activity in PC12 cells. 244 2

The mitogenic activity of several growth factors is mediated by calcium-dependent signal transduction. Calmodulin (CaM) binding proteins such as CaM-dependent protein kinases are important components of this pathway and may be altered in diseases characterized by abnormal cell growth. CaM kinase II is believed to regulate the phosphorylation of microtubular-associated proteins and control the initiation of DNA synthesis. Furthermore, drugs that inhibit CaM-mediated signal transduction also inhibit cellular proliferation and are cytotoxic to numerous malignant cell lines, including those established from malignant gliomas. Yet, little is known about CaM-dependent protein kinases in these tumors. Therefore, we have investigated the activity and distribution of CaM-dependent protein kinase II in normal and malignant glial tissues, a kinase believed to play a critical role in cell cycle regulation. C6 and 9L cells contained kinase activities that were activated by Ca2+/CaM and inhibited by trifluoperazine. Tissue extracts from these cell lines and from rat brain white matter phosphorylated exogenous synapsin I in a pattern consistent with the presence of CaM kinase II activity as determined by phosphopeptide mapping. CaM kinase II activity was confirmed using a specific peptide substrate and inhibitor. An unexpected finding was that glioma lines, but not rat brain white matter, also contained a CaM-dependent protein kinase detected by the phosphorylation of a M(r) 100,000 protein, subsequently identified as elongation factor 2, the only known substrate for CaM kinase III.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Calmodulin-dependent protein kinases in rat glioblastoma. 764 41

Ca2+ is widely recognized as an essential intracellular second messenger in eukaryotic systems regulating processes such as muscle contraction, neurotransmitter release, gene expression and cell proliferation. The effects of Ca2+ are frequently mediated via interaction with calmodulin (CaM) and strong evidence indicates, in turn, that the effects of Ca2+/CaM are often achieved through the regulation of protein phosphorylation. A family of CaM-dependent protein kinases has been identified that includes: myosin light chain kinase, phosphorylase kinase, CaM kinase I, CaM kinase II, EF-2 kinase (CaM kinase III) and CaM kinase IV. The structure, regulation and function of this important family of second messenger-regulated protein kinases will be briefly reviewed.
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PMID:Calcium/calmodulin-dependent protein kinases. 780 66

We have previously shown that Ca2+/calmodulin-dependent phosphorylation of the 100-kDa protein dramatically increases during the early period of myoblast fusion and treatment of calmodulin antagonists, such as trifluoperazine, blocks the fusion. Here, we show that cAMP treatment of primary cultures of chick embryonic myoblasts blocks 100-kDa protein phosphorylation. This effect is dose-dependent and can be reversed upon removal of the nucleotide from the culture media. However, cAMP shows little or no effect on accumulation of the 100-kDa protein. Furthermore, phosphorylation of the 100-kDa protein by the partially purified Ca2+/calmodulin-dependent protein kinase (CaM kinase III) from cAMP-treated cells occurs to a much lower extent than that from untreated cells. Nevertheless, cAMP-sensitive protein kinase does not seem to be directly involved in phosphorylation and inactivation of CaM kinase III, because preincubation of cAMP with the myoblast extracts lacking the endogenous 100-kDa protein does not show any effect on activity of CaM kinase III. Similar to its effect on 100-kDa protein phosphorylation, cAMP reversibly inhibits the fusion of cultured myoblasts. Moreover, treatment with forskolin or theophylline, which is known to elevate the intracellular cAMP level, also reversibly blocks both protein phosphorylation and myoblast fusion. On the other hand, cAMP shows little or no effect on accumulation of muscle-specific proteins, such as creatine kinase and tropomyosin. These results suggest that cAMP is involved in down-regulation of both 100-kDa protein phosphorylation and membrane fusion of cultured myoblasts. These results also suggest that the cAMP-mediated inhibition of 100-kDa protein phosphorylation may be associated with its inhibitory effect on myoblast fusion.
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PMID:Cyclic AMP negatively modulates both Ca2+/calmodulin-dependent phosphorylation of the 100-kDa protein and membrane fusion of chick embryonic myoblasts. 808 35

We have attempted to identify islet Ca2+/calmodulin-dependent protein kinase (CaM kinase) by comparing its activity with purified brain CaM kinase II. Islet CaM kinase, in the presence of calmodulin and Ca2+, phosphorylated major endogenous substrates of 102, 57 and 53 kDa and also exogenous glycogen synthase; brain CaM kinase II phosphorylated glycogen synthase and peptides of 57 and 53 kDa. Alloxan (1 mM) inhibited the phosphorylation of glycogen synthase and the 102, 57 and 53 kDa islet peptides by islet CaM kinase; the phosphorylation of glycogen synthase and the 57 and 53 kDa substrates by brain CaM kinase II was also inhibited by alloxan. The Ca2+ and calmodulin-dependencies of phosphorylation of the endogenous islet substrates differed. In the presence of 400 nM calmodulin, half-maximal phosphorylation was attained at Ca2+ concentrations of 80 +/- 9, 401 +/- 61 and 459 +/- 59 nM for the 102, 57 and 53 kDa substrates respectively. In the presence of 10 microM Ca2+, half-maximal phosphorylation was attained at calmodulin concentrations of 9 +/- 2, 38 +/- 2.5 and 37 +/- 2 nM for the 102, 57 and 53 kDa substrates respectively. Differential centrifugation located the 102 kDa substrate in the post-100,000 g supernatant and the 57 and 53 kDa substrates in the particulate fraction. These data suggest that islet CaM kinase is similar to, if not identical with, brain CaM kinase II, but that phosphorylation of the endogenous 102 kDa substrate occurs by a distinct kinase which shows different sensitivities to Ca2+ and calmodulin. This kinase probably corresponds to CaM kinase III and the 102 kDa peptide to elongation factor 2 (EF-2), since the 102 kDa peptide was shown to undergo ADP-ribosylation in the presence of diphtheria toxin and NAD+.
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PMID:Characterization of Ca2+/calmodulin-dependent protein kinase in rat pancreatic islets. 838 51

eEF-2 kinase is a ubiquitous Ca2+/calmodulin-dependent protein kinase that is specific for protein synthesis elongation factor-2 (eEF-2). This study describes an improved procedure for the purification of eEF-2 kinase from rabbit reticulocyte lysate. The eEF-2 kinase preparation was used to raise polyclonal antibodies, which immunoprecipitated eEF-2 kinase protein and activity from rabbit reticulocyte lysate. The antibodies recognized a single 103 kDa band in extracts from several cell lines including NIH 3T3, PC12, C6 glioma, HeLa, and MCF-7 breast carcinoma. However, there was no immunoreactivity in extracts of rabbit or bovine liver or rabbit kidney despite the presence of abundant eEF-2 kinase activity in these tissues. Exposure of PC12 cells to nerve growth factor (NGF) resulted in rapid down-regulation of eEF-2 kinase activity and a decrease in immunoreactivity. After 24 h of incubation with NGF, the activity of the kinase recovered to 80% of initial values. In contrast, the immunoreactivity of eEF-2 kinase continued to decrease. These data suggest that tissue-specific isoforms of eEF-2 kinase may exist and that these isoforms may be regulated by growth factors.
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PMID:Elongation factor-2 kinase: immunological evidence for the existence of tissue-specific isoforms. 894 13

Recent evidence suggests that the machinery of protein synthesis may provide novel targets for anticancer drugs. For example, aberrations in protein synthesis are commonly encountered in established cancers, and disruption by mutation or overexpression of translation factors can cause cellular transformation. We previously demonstrated that the activity of eukaryotic elongation factor 2 (eEF-2) kinase was markedly increased in several forms of malignancy and that nonspecific inhibitors of this enzyme promoted cell death. On the basis of the predicted amino acid sequence of eEF-2 kinase deduced from the cloned cDNA, we hypothesized that inhibitors of prokaryotic histidine kinases might also inhibit the activity of eEF-2 kinase. We describe herein the screening of a series of imidazolium histidine kinase inhibitors and the identification of an active lead compound, NH125. NH125 inhibited eEF-2 kinase activity (IC(50) = 60 nM) in vitro, blocked the phosphorylation of eEF-2 in intact cells, and showed relative selectivity over other protein kinases: protein kinase C (IC(50) = 7.5 microM), protein kinase A (IC(50) = 80 microM), and calmodulin-dependent kinase II (IC(50) > 100 microM). NH125 decreased the viability of 10 cancer cell lines with IC(50)s ranging from 0.7 to 4.7 microM. Forced overexpression of eEF-2 kinase in a glioma cell line produced 10-fold resistance to NH125. In conclusion, these results suggest that identification of potent inhibitors of eEF-2 kinase may lead to the development of new types of anticancer drugs.
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PMID:Identification and characterization of an inhibitor of eukaryotic elongation factor 2 kinase against human cancer cell lines. 1458 88