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

H2O2, like other oxidants, is known to act as a mitogen at low concentrations in resting Balb/3T3 or mouse epidermal JB6 cells. We described previously that H2O2 induces some early response genes in Balb/3T3 cells. We extended these observations using another cell line, MC3T3 (mouse osteoblastic) cells by examination of transcriptional activity of these genes and by using inhibitors of protein kinases. H2O2 increased the expressions of c-fos, c-jun, egr-1 and JE genes which are known to be early response genes and are induced by mitogenic stimuli in many types of cells. Exogenous addition of H2O2 increased the mRNA levels of these genes, the kinetics of increase being similar to those of their inductions by a phorbol ester or serum. Nuclear run-on transcription showed that this induction occurred at the transcriptional level. H2O2 at 0.1-0.2 mM induced maximal expressions of c-fos and c-jun, whereas 0.3 mM H2O2 was required for induction of stress-induced heme oxygenase mRNA. The inductions of c-fos and c-jun were inhibited by 50 microM H7, a protein kinase inhibitor that is relatively specific for protein kinase C, but were not affected by H9, relatively specific for cAMP-dependent protein kinase. In cells pretreated with 12-O-tetradecanoylphorbol 13-acetate, however, in which protein kinase was supposed to be downregulated, H2O2 induced c-fos and heme oxygenase as efficiently as in untreated cells. H2O2 did not increase the phosphorylation of p80 protein, which is known to be a substrate for protein kinase C. Thus, H2O2 seemed to induce c-fos and c-jun by activating protein kinases distinct from protein kinase C. Activity of the chloramphenicol acetyltransferase gene under control of the serum-response element of human c-fos genes was increased by H2O2 treatment, whereas that under control of cAMP-response element was not affected. These results indicate that the inductions by H2O2 of c-fos and possibly other early response genes are mediated through activation of the serum-response element in their enhancer.
 ...
PMID:Transcriptional activation of early-response genes by hydrogen peroxide in a mouse osteoblastic cell line. 191 80

In luteal and granulosa cells, hydrogen peroxide abruptly inhibits activation of adenylate cyclase by receptor-bound gonadotropin and blocks steroidogenesis. In the present studies a post-cAMP site of peroxide action on inhibition of steroidogenesis was investigated. Steroidogenesis, stimulated by dibutyryl or 8-bromo-cAMP, was inhibited by hydrogen peroxide. Yet, cAMP-dependent protein kinase activation in cytosol or intact cells was unaffected by peroxide treatment. Hydrogen peroxide also did not inhibit the activity of cholesterol esterase and acyl coenzyme-A:acyltransferase. Progesterone synthesis was maximally increased 5- to 50-fold with 25- and 22-hydroxycholesterol, respectively. Unlike that seen with cAMP analogs and LH, however, progestin synthesis stimulated by these cell- and mitochondria-permeant cholesterol analogs was not inhibited by hydrogen peroxide. Treatment of animals with amino-glutethimide produces a marked accumulation of steroidogenic cholesterol substrate and a large increase in hormone-independent steroidogenesis in subsequently isolated and washed luteal tissue. In this paradigm, hydrogen peroxide did not inhibit elevated basal progesterone synthesis in luteal cells produced by in vivo aminoglutethimide treatment, yet LH-stimulated steroidogenesis was blocked. However, treatment of luteal cells with hydrogen peroxide inhibited pregnenolone synthesis in isolated mitochondria, an effect partially reversed by the addition of luteal cell cytosol. In summary, while peroxide inhibited cAMP-dependent steroidogenesis, it did not appear to inhibit protein kinase activation or mobilization of cholesterol from intracellular esterified stores. Although peroxide inhibited pregnenolone synthesis, it had no effect on steroidogenesis when substrate was made available by either addition of cholesterol analogs or prior treatment with aminoglutethimide in vivo. We conclude, therefore, that hydrogen peroxide inhibits steroidogenesis by blocking intracellular transport of cholesterol to mitochondria or translocation of cholesterol across the outer mitochondrial membrane.
 ...
PMID:Evidence that hydrogen peroxide blocks hormone-sensitive cholesterol transport into mitochondria of rat luteal cells. 203 71

The effects of theophylline upon human alveolar macrophage function were assessed and compared with its action upon macrophage cyclic nucleotide phosphodiesterase (PDE) activity and cyclic adenosine monophosphate (cAMP) levels. In the concentration range of 10 mumol/liter to 1 mmol/liter, theophylline caused a concentration-dependent inhibition of opsonized zymosan-stimulated hydrogen peroxide (H2O2) generation and PDE-catalyzed cAMP hydrolysis and increased the cellular cAMP content. Macrophage H2O2 generation was also inhibited by forskolin, an activator of adenylyl cyclase, but whereas theophylline (1 mmol/liter) and forskolin (1 mumol/liter) exhibited a synergic elevation of macrophage cAMP, there was no synergy between the two agents in the inhibition of respiratory burst. The inhibition of H2O2 generation by theophylline was reversed by the competitive inhibitor of cAMP-dependent protein kinase, (Rp)8-bromoadenosine cyclic 3':5'-monophosphorothioate (Rp-8-Br-cAMPS; 100 mumol/liter), indicating that the functional effect of theophylline was mediated through the elevation of cAMP. The inhibition of H2O2 generation by theophylline was not affected by adenosine deaminase (0.1 U/ml), indicating that the inhibition did not involve adenosine antagonism. It is concluded that theophylline exerts a direct inhibitory action upon human alveolar macrophage function through the elevation of cAMP levels as a result of PDE inhibition, and that this effect is observed at concentrations of theophylline that may be achieved in serum during therapy.
 ...
PMID:Theophylline suppresses human alveolar macrophage respiratory burst through phosphodiesterase inhibition. 817 21

Sperm motility is a process which involves a cascade of events mediated by cAMP and Ca2+, cAMP in the initiation of flagellar movement, and Ca2+ in the regulation of beat asymmetry, and it has been suggested that these two messengers act through phosphorylation/ dephosphorylation of axonemal proteins. Only a few studies on human sperm protein phosphorylation have been reported and no relation of this process with motility or other function has been established. In the present study, phosphorylation of human sperm proteins was performed using detergent-demembranated spermatozoa, in which motility is reactivated by the addition of ATP. This system allows direct accessibility of intracellular kinases to [32P] gamma ATP and allows some relation between protein phosphorylation and flagellar movements. After electrophoresis and autoradiography, numerous phosphoproteins were detected. Phosphorylation of 2 proteins (36 and 51 kDa) was stimulated by cAMP in a concentration-dependent manner, and this increase was prevented by inhibitors of cAMP-dependent protein kinase. In order to characterize phosphoproteins originating from the cytoskeleton or axoneme, detergent extracted spermatozoa were also subjected to phosphorylation. Three major phosphorylated proteins (14.8, 15.3, and 16.2 kDa) were detected, the first two expressing cAMP-dependency according to their cAMP concentration-dependent increase in phosphorylation and the reversal of this effect by inhibitors of cAMP-dependent protein kinase. Proteins phosphorylation during the reactivation of demembranated spermatozoa previously immobilized H2O2, xanthine + xanthine oxidase-generated reactive oxygen species, or the oxidative phosphorylation uncoupler rotenone, revealed increases in cAMP-independent phosphorylation of proteins of 16.2, 46, and 93 kDa. These results documenting human sperm phosphoproteins form a base for further studies on the role of protein phosphorylation in sperm functions.
 ...
PMID:Phosphorylation of Triton X-100 soluble and insoluble protein substrates in a demembranated/reactivated human sperm model. 911 18

Hypoxia/reoxygenation injury in vitro causes endothelial cell cytoskeletal rearrangement that is related to increased monolayer permeability. Nonmuscle filamin (ABP-280) promotes orthogonal branching of F-actin and links microfilaments to membrane glycoproteins. Human umbilical vein endothelial cell monolayers are exposed to H2O2 (100 microM) for 1-60 min, with or without modulators of cAMP-dependent second-messenger pathways, and evaluated for changes in filamin distribution, cAMP levels, and the formation of gaps at interendothelial junctions. Filamin translocates from the membrane-cytoskeletal interface to the cytosol within 1 min of exposure to H2O2. This is associated with a decrease in endothelial cell cAMP levels from 83 pmoles/mg protein to 15 pmoles/mg protein. Intercellular gaps form 15 min after H2O2 treatment and progressively increase in number and diameter through 60 min. Both filamin redistribution and actin redistribution are associated with decreased phosphorylation of filamin and are prevented by activation of the cAMP-dependent protein kinase pathway. A synthetic peptide corresponding to filamin's C-terminal, cAMP-dependent, protein kinase phosphorylation site effectively induces filamin translocation and intercellular gap formation, which suggests that decreased phosphorylation of filamin at this site causes filamin redistribution and destabilization of junctions. These data indicate that H2O2-induced filamin redistribution and interendothelial cell gap formation result from inhibition of the cAMP-dependent protein kinase pathway.
 ...
PMID:H2O2-induced filamin redistribution in endothelial cells is modulated by the cyclic AMP-dependent protein kinase pathway. 928 57

Exposure to reactive oxygen species (ROS) is associated with tissue damage in the lung and may be a common element in the pathogenesis of all inflammatory lung diseases. Exposure to the ROS hydrogen peroxide (H2O2) evoked a rapid increase in transepithelial anion secretion across monolayers of the human submucosal gland serous cell line Calu-3. This increase was almost entirely abolished by the addition of diphenylamine-2-carboxylate (DPC), implicating the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel in the response. The response was also reduced by inhibitors of basolateral K+ channels. Studies of electrically isolated apical and basolateral membranes revealed that H2O2 stimulated both apical Cl- and basolateral K+ conductances (G(Cl) and G(K)). Apical G(Cl) was sensitive to DPC, but unaffected by 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), suggesting that CFTR is the major anion conduction pathway mediating the response to H2O2. Additionally, H2O2 had no effect on G(Cl) in the presence of the adenylate cyclase inhibitor SQ22536 or following maximal stimulation of G(Cl) with forskolin, implicating the cAMP-dependent protein kinase pathway in the apical response to H2O2. Basolateral G(K) was reduced by the K+ channel inhibitors clotrimazole and clofilium, indicating roles for KCNN4 and KCNQ1 in the H2O2-stimulated response. We propose that ROS-stimulated anion secretion from serous cells plays an important role in keeping the airways clear from damaging radicals that could potentially initiate tissue destruction. Our finding that this response is CFTR dependent suggests that an important host defence mechanism would be dysfunctional in the cystic fibrosis (CF) lung. Loss of this compensatory protective mechanism could expose the CF lung to ROS for extended periods, which could be important in the pathogenesis of CF lung disease.
 ...
PMID:Oxidant stress stimulates anion secretion from the human airway epithelial cell line Calu-3: implications for cystic fibrosis lung disease. 1218 Dec 92

A study is presented of the effect of the cAMP cascade on oxygen metabolism in mammalian cell cultures. Serum-starvation of the cell cultures resulted in depression of the forward NADH-ubiquinone oxidoreductase activity of complex I, decreased content of glutathione, and enhancement of the cellular level of H2O2. Depressed transcription of cytosolic Cu/Zn-SOD 1, mitochondrial glutathione peroxidase and catalase was also observed. Activation of the cAMP cascade reversed the depression of the activity of complex I and the accumulation of H2O2. The effect of cAMP involved the cAMP-dependent protein kinase.
 ...
PMID:Regulation by the cAMP cascade of oxygen free radical balance in mammalian cells. 1667 93

Exercise increases glucose transport into skeletal muscle via a pathway that is poorly understood. We investigated the role of endogenously produced reactive oxygen species (ROS) in contraction-mediated glucose transport. Repeated contractions increased 2-deoxyglucose (2-DG) uptake roughly threefold in isolated, mouse extensor digitorum longus (fast-twitch) muscle. N-Acetylcysteine (NAC), a non-specific antioxidant, inhibited contraction-mediated 2-DG uptake by approximately 50% (P < 0.05 versus control values), but did not significantly affect basal 2-DG uptake or the uptake induced by insulin, hypoxia or 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR, which mimics AMP-mediated activation of AMP-activated protein kinase, AMPK). Ebselen, a glutathione peroxidase mimetic, also inhibited contraction-mediated 2-DG uptake (by almost 60%, P < 0.001 versus control values). Muscles from mice overexpressing Mn2+-dependent superoxide dismutase, which catalyses H2O2 production from superoxide anions, exhibited a approximately 25% higher rate of contraction-mediated 2-DG uptake versus muscles from wild-type control mice (P < 0.05). Exogenous H2O2 induced oxidative stress, as judged by an increase in the [GSSG]/[GSH + GSSG] (reduced glutathione + oxidized glutathione) ratio to 2.5 times control values, and this increase was substantially blocked by NAC. Similarly, NAC significantly attenuated contraction-mediated oxidative stress as judged by measurements of glutathione status and the intracellular ROS level with the fluorescent indicator 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein (P < 0.05). Finally, contraction increased AMPK activity and phosphorylation approximately 10-fold, and NAC blocked approximately 50% of these changes. These data indicate that endogenously produced ROS, possibly H2O2 or its derivatives, play an important role in contraction-mediated activation of glucose transport in fast-twitch muscle.
 ...
PMID:Role of reactive oxygen species in contraction-mediated glucose transport in mouse skeletal muscle. 1680 55

Dihydropyrimidinase-like 3 (DPYSL3) is believed to play a role in neuronal differentiation, axonal outgrowth and neuronal regeneration, as well as cytoskeleton organization. Recently we have shown that glutamate excitotoxicity and oxidative stress result in calpain-dependent cleavage of DPYSL3, and that NOS plays a role in this process [R. Kowara, Q. Chen, M. Milliken, B. Chakravarthy, Calpain-mediated truncation of dihydropyrimidinase-like 3 protein (DPYSL3) in response to NMDA and H2O2 toxicity, J. Neurochem. 95 (2005) 466-474; R. Kowara, K.L. Moraleja, B. Chakravarthy, Involvement of nitric oxide synthase and ROS-mediated activation of L-type voltage-gated Ca(2+) channels in NMDA-induced DPYSL3 degradation, Brain Res. 1119 (2006) 40-49]. The present study investigates the involvement of PLA(2) signaling in NMDA-induced DPYSL3 degradation. Exposure of rat primary cortical neurons (PCN) to PLA(2) and COX-2 inhibitors significantly prevented NMDA-induced DPYSL3 degradation. Since the metabolic product of PLA(2) signaling, PGE(2), which augments toxic effect of NMDA, is known to stimulate cAMP, the effect of adenyl cyclase activator (forskolin plus IBMX) and inhibitor (MDL12,300) on NMDA-induced DPYSL3 degradation was tested. Our data indicate that the activation of adenyl cyclase contributes to NMDA-induced DPYSL3 degradation. Furthermore, cAMP-dependent protein kinase (PKA) inhibitor PKI (14-22) provided additional evidence of PKA involvement in NMDA-induced DPYSL3 degradation. In summary, the obtained data show the contribution of PLA(2) signaling to NMDA-induced calpain activation and subsequent degradation of synaptic protein DPYSL3.
 ...
PMID:PLA(2) signaling is involved in calpain-mediated degradation of synaptic dihydropyrimidinase-like 3 protein in response to NMDA excitotoxicity. 1805 48

Reactive oxygen species (ROS) play an important role in cellular function via the activation of signaling cascades. ROS have been shown to affect mitochondrial biogenesis, morphology, and function. Their beneficial effects are likely mediated via the upregulation of transcriptional regulators such as peroxisome proliferator-activated receptor-gamma coactivator-1 protein-alpha (PGC-1alpha). However, the ROS signals that regulate PGC-1alpha transcription in skeletal muscle are not understood. Here we examined the effect of H2O2 on the regulation of PGC-1alpha expression, and its relationship to AMPK activation. We demonstrate that 24 h of exogenous H2O2 treatment increased PGC-1alpha promoter activity and mRNA expression. Both effects were blocked with the addition of N-acetylcysteine, a ROS scavenger. These effects were mediated, in part, via upstream stimulatory factor-1/Ebox DNA binding and involved 1) interactions with downstream sequences and 2) the activation of AMPK. Elevated ROS led to the activation of AMPK, likely via a decline in ATP levels. The activation of AMPK using 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside increased PGC-1alpha promoter activity and mRNA levels but reduced ROS production. Thus the net effect of AMPK activation on PGC-1alpha expression was a result of increased transcriptional activation, counterbalanced by reduced ROS production. The effects of H2O2 on PGC-1alpha expression differed depending on the level of ROS within the cell. Low levels of ROS result in reduced PGC-1alpha mRNA in the absence of an effect on PGC-1alpha promoter activation. In contrast, elevated levels of H2O2 induce PGC-1alpha transcription indirectly, via AMPK activation. These data identify unique interactions between ROS and AMPK activation on the expression of PGC-1alpha in muscle cells.
 ...
PMID:Interactions between ROS and AMP kinase activity in the regulation of PGC-1alpha transcription in skeletal muscle cells. 1900 63


1 2 3 4 Next >>