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)

Programmed death (apoptosis) of the rat myelocytic leukemic cell line IPC-81 was triggered by cyclic adenosine monophosphate (cAMP) analogs or by agents (cholera toxin, prostaglandins) increasing the endogenous cAMP level. The induction of cell death by cholera toxin was preceded by increased activation of cAMP-kinase. Cell lysis started already 5 hr after cAMP challenge and was preceded by internucleosomal DNA fragmentation and morphological changes characteristic of apoptosis. The cell suicide could be prevented by inhibitors of macromolecular synthesis. cAMP analogs induced cell death in a positively cooperative manner (apparent Hill coefficient of 2.9), indicating that triggering of the apoptotic process was under stringent control. There was a strong synergism between cAMP analogs complementing each other in the activation of cAMP-dependent protein kinase I (cAKI). No such synergism was noted for analogs complementing each other in the activation of cAKII. It is concluded that apoptosis can be induced solely by activation of cAKI. The IPC-81 cells expressed about four times more cAKI than cAKII. The expression of cAK subunits, on the protein and mRNA levels, was only minimally affected by cholera toxin treatment.
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PMID:Programmed cell death (apoptosis) is induced rapidly and with positive cooperativity by activation of cyclic adenosine monophosphate-kinase I in a myeloid leukemia cell line. 184 37

Novel (Rp)-cAMPS analogs differed widely in ability to antagonize cAMP activation of pure cAMP-dependent protein kinase I and II and to antagonize actions of cAMP on gene expression, shape change, apoptosis, DNA replication, and protein phosphorylation in intact cells. These differences were related to different abilities of the analogs to stabilize the holoenzyme form relative to the dissociated form of cAMP kinase type I and II. (Rp)-8-Br-cAMPS and (Rp)-8-Cl-cAMPS were the most potent cAMP antagonists for isolated type I kinase and for cells expressing mostly type I kinase, like IPC-81 leukemia cells, fibroblasts transfected with type I regulatory subunit (RI), and primary hepatocytes. It is proposed that (Rp)-8-Br-cAMPS or (Rp)-8-Cl-cAMPS should replace (Rp)-cAMPS as the first line cAMP antagonist, particularly for studies in cells expressing predominantly type I kinase. The phosphorylation of endogenous hepatocyte proteins was affected oppositely by (Rp)-8-Br-cAMPS and increased cAMP, indicating that (Rp)-8-Br-cAMPS inhibited basal cAMP-kinase activity. The inhibition of basal kinase activity was accompanied by enhanced DNA replication, an effect which could be reproduced by microinjected mutant cAMP-subresponsive RI. It is concluded that the basal cAMP-kinase activity exerts a tonic inhibition of hepatocyte replication. (Rp)-8-Br-cAMPS and microinjected RI also desensitized hepatocytes toward inhibition of DNA synthesis by interleukin-1 beta. This indicates that basal cAMP-kinase activity can have a permissive role for the action of another (interleukin-1 beta) signaling pathway.
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PMID:Novel (Rp)-cAMPS analogs as tools for inhibition of cAMP-kinase in cell culture. Basal cAMP-kinase activity modulates interleukin-1 beta action. 765 38

cAMP induced rapid apoptosis (> 90% cell death in 6 h) of non-growth-arrested rat leukemia IPC-81 cells. A cell clone selected for cAMP resistance had a normally functioning apoptotic machinery whose triggering required about 30-fold higher cellular cAMP than in the parent cells. The cAMP subresponsiveness was due to a heterozygous point mutation (Ala336-->Asp) in the RI subunit of cAMP-dependent protein kinase I. In fact, apoptosis correlated with intracellular cAMP binding to the subresponsive RI. The mutated alanine is invariantly present in cyclic nucleotide kinases, but of unknown function. The mutation decreased the cAMP affinity to site B by increasing the cAMP dissociation rate 500x. The ability of site B to discriminate adenine-modified cAMP analogues was affected, suggesting that Ala336 faced the adenine moiety of cAMP. That the heterozygously expressed RID336 was a dominant suppressor of apoptosis was explained by a higher expression of R than C subunits in the mutant cells by preferential expression of the mutant form of RI, and by the ability of mutant RI to exert dominant negative control of activation of wild type cAMP kinase at moderate cAMP levels. Apoptosis was induced at a similar cAMP level in cells treated with cholera toxin or other cAMP elevating agents, indicating that cAMP kinase was essential for toxin action.
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PMID:Antiapoptotic effect of heterozygously expressed mutant RI (Ala336-->Asp) subunit of cAMP kinase I in a rat leukemia cell line. 838 40

Rat IPC-81 promyelocytic leukemia cells responded to cAMP analog by undergoing apoptotic cell death both when anchored to fibronectin and when free in the medium. The protein kinase C stimulator 12-O-tetradecanoylphorbol 13-acetate enhanced the anchoring to substratum without impeding cAMP-induced cell death. The immobilized cells could be microinjected. This made it possible to study the effect on apoptosis of microinjected catalytic (C alpha) and regulatory (RI alpha D199) subunits of cAMP-dependent protein kinase as well as of phosphatase inhibitors. Microinjection of C alpha reproduced the morphological effects of cAMP, including nuclear fragmentation. RI alpha D199 blocked the effect of C alpha. Injection of microcystin-LR, which inhibits protein phosphatases 1 and 2A, led to pronounced apoptoid changes of the leukemia cells, but failed to produce nuclear fragmentation. Microinjection of peptide inhibitors ("inhibitor 1" and "inhibitor 2") specific for phosphatase 1 had no effect on cell morphology. The failure of the phosphatase inhibitors to reproduce completely the effect of the C subunit underscores the specificity of action of the latter.
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PMID:Microinjected catalytic subunit of cAMP-dependent protein kinase induces apoptosis in myeloid leukemia (IPC-81) cells. 838 20

Vigorous apoptosis is induced 3-4 hours after activation of cAMP-dependent protein kinase I in the rat myeloid leukemia cell line IPC-81 [J. Cell. Physiol. 146 (1991) 73-80]. We will report a novel feature of apoptosis in these cells: a selective and temporarily ordered cleavage within the two largest 28S ribosomal RNA variable regions (V3 and V13). The cleavage of 28S rRNA coincided with internucleosomal DNA fragmentation and cessation of cellular protein synthesis. The implication of 28S variable regions as targets in apoptosis is a clue to the function of these so far apparently superfluous parts of eukaryotic ribosomes.
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PMID:Selective cleavage of 28S rRNA variable regions V3 and V13 in myeloid leukemia cell apoptosis. 841 4

The cAMP pathway plays a central role in the response to hormonal signals for cell proliferation, differentiation and apoptosis. In IPC-81 leukaemia cells, activation of the cAMP pathway by prostaglandin E1 treatment, or other cAMP-elevating agents, induces apoptosis within 4-6 h. Inhibition of mRNA or protein synthesis during the first 2 h of cAMP induction protects cells from apoptosis, suggesting a requirement for early gene expression. cAMP-dependent protein kinase phosphorylates a class of nuclear factors and thereby regulates the transcription of a specific set of genes. Here we show that CREM (cAMP Responsive Element Modulator) expression is induced rapidly upon prostaglandin E1 treatment of IPC-81 cells. The induced transcripts correspond to the early product ICER (Inducible cAMP Early Repressor). ICER expression remains elevated until the burst of cell death. Protein synthesis inhibitors which prevent cAMP-induced apoptosis also block de novo ICER synthesis. Transfected IPC-81 cell lines, constitutively expressing high level of ICER are resistant to cAMP-induced cell death. In these transfected cells, cAMP fails to upregulate the ICER transcripts demonstrating that ICER exerts strongly its repressor function on CRE-containing genes. That an early expression of ICER blocks apoptosis, suggests that gene repression by endogenous ICER in IPC-81 is insufficient or occurs too late to protect cells against death. ICER transfected cells rescued from cAMP-induced apoptosis are growth arrested. It shows for the first time that CREM activation directly participates to the decision of the cell to die. ICER, by sequentially repressing distinct sets of CRE-containing genes could modulate cell fate.
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PMID:The transcriptional repressor ICER and cAMP-induced programmed cell death. 926 69

Treatment of IPC-81 cells led to inhibition of protein synthesis, which was accompanied by an increase in the average size of polysomes and a decreased rate of elongation, indicating that it involved inhibition of peptide chain elongation. This inhibition was also associated with increased phosphorylation of elongation factor eEF2 (which inhibits its activity) and enhanced Ca2+/calmodulin-independent activity of eEF2 kinase. Previous work has shown that phosphorylation of eEF2 kinase by cAMP-dependent protein kinase (cAPK) in vitro induces such activator-independent activity, and the present data show that such a mechanism can occur in intact cells to link physiological levels of cAPK activation with inhibition of protein synthesis.
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PMID:cAMP inhibits translation by inducing Ca2+/calmodulin-independent elongation factor 2 kinase activity in IPC-81 cells. 1003 55

An elevated cAMP concentration results in growth arrest and protein synthesis-dependent apoptosis in the promyelocytic leukaemia cell line IPC-81. A comparison of two-dimensional gels of extracts from these cells labelled with [(35)S]methionine revealed that five distinct protein spots were induced by cAMP in a protein-synthesis-dependent manner. The spots seemed to result from the acidic shift of a precursor protein. The most abundant spot was phospho-actin. The spots induced by cAMP in intact cells were induced by cAMP-dependent protein kinase (cAPK) during the translation in vitro of mRNA from the leukaemia cells. The effect of cAPK was strictly co-translational, none of the spots being induced when cAPK was added after translation. This suggested that the protein spots arose by co-translational phosphorylation catalysed by cAPK. Two of the protein spots, phospho-actin and a protein with a molecular mass of 30 kDa and an isoelectric point of 4.5, were studied further with respect to expression. They were produced during the whole pre-apoptotic period, had cellular half-lives of several hours and were induced by the same concentrations of cAMP analogue that induced apoptosis. It is suggested that the accumulation of co-translationally modified proteins could be important for long-term cAMP signalling.
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PMID:cAMP induces co-translational modification of proteins in IPC-81 cells. 1045 24