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:2.7.11.2 (PDK1)
2,238 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ongoing DNA damage caused by reactive oxygen species generated during oxidative metabolism is considered a key factor contributing to cell aging as well as preconditioning cells to neoplastic transformation. We postulated before that a significant fraction of constitutive histone H2AX phosphorylation (CHP) and constitutive activation of ATM (CAA) seen in untreated normal and tumor cells occurs in response to such DNA damage. In the present study, we provide further evidence in support of this postulate. The level of ATM activation and H2AX phosphorylation, detected immunocytochemically, has been monitored in WI-38, A549, and TK6 cells treated with H2O2 as well as growing under conditions known or suspected to affect the level of endogenous oxidants. Thirty- to 60-min exposure of cells to 100 or 200 microM H2O2 led to an increase in the level of H2AX phosphorylation and ATM activation, particularly pronounced (nearly fivefold) in S-phase cells. Cell growth for 24-48 h under hypoxic conditions (3% O2) distinctly lowered the level of CHP and CAA while it had minor effect on cell cycle progression. Treatment (4 h) with 0.1 or 0.3 mM 3-bromopyruvate, an inhibitor of glycolysis and mitochondrial oxidative phosphorylation, reduced the level of CHP (up to fourfold) and also decreased the level of CAA. Growth of WI-38 cells in 2% serum concentration for 48 h led to a 25 and 30% reduction in CHP and CHA, respectively, compared with cells growing in 10% serum. The antioxidant vitamin C (2 mM) reduced CHP and CAA by 20-30% after 24 h of treatment, while the COX-2 inhibitor celecoxib (5 microM) had a minor effect on CHP and CAA, though it decreased the level of H2O2-induced H2AX phosphorylation and ATM activation. In contrast, dichloroacetate known to shift metabolism from anaerobic to oxidative glycolysis through its effect on pyruvate dehydrogenase kinase enhanced the level of CHP and CAA. Our present data and earlier observations strongly support the postulate that a large fraction of CHP and CAA occurs in response to DNA damage caused by metabolically generated oxidants. Cytometric analysis of CHP and CAA provides the means to measure the effectiveness of exogenous factors, which either through lowering aerobic metabolism or neutralizing radicals may protect DNA from such damage.
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PMID:Cytometric assessment of DNA damage by exogenous and endogenous oxidants reports aging-related processes. 1794 96

Nuclear factor kappaB (NF-kappaB) and activator protein 1 are transcription factors involved in the regulation of cell proliferation that play important roles in tumorigenesis. We investigated whether these two factors cooperate for transcriptional regulation of cyclin D1 (CCND1), a gene whose deregulation is critical during carcinogenesis. We demonstrate that overexpression of JunD in human hepatocarcinoma cells strongly activates transcription mediated by the kappaB2 site of the CCND1 promoter in reporter assays, in a manner strictly dependent on the presence of NF-kappaB proteins. Serum stimulation increased the expression of p65, p50, c-Fos, c-Jun and JunD and induced the recruitment of p65, p50 and JunD to the kappaB2 site of the promoter in DNA pull-down assays. Chromatin immunoprecipitation (ChIP) analysis confirmed the serum-induced recruitment of JunD to the promoter in vivo and showed that the presence of JunD was dependent on the presence of p65 and p50, indicating a protein-protein-dependent mechanism of JunD recruitment. Serum-induced activation of protein binding to kappaB2 correlated with high levels of phosphoinositide-dependent protein kinase-1 (PDK-1) phosphorylation. Both LY294002, a specific inhibitor of phosphatidylinositol 3-kinase (PI3K), and overexpression of a dominant-negative form of PDK-1 inhibited the JunD-stimulating effect in reporter assays. LY294002 also prevented the serum-induced recruitment of JunD, but not p65 or p50 to the promoter in ChIP assay. JunD-p65 complexes, identified in vivo by co-immunoprecipitation, were decreased by LY294002 and by small interfering RNA inhibition of PDK-1. Taken together, our data demonstrate a PI3K/PDK-1-dependent functional cooperation of NF-kappaB and JunD in the transcriptional regulation of CCND1 by serum.
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PMID:Jun D cooperates with p65 to activate the proximal kappaB site of the cyclin D1 promoter: role of PI3K/PDK-1. 1817 38

Morusin is a pure compound isolated from root bark of Morusaustralis (Moraceae). In this study, we demonstrated that morusin significantly inhibited the growth and clonogenicity of human colorectal cancer HT-29 cells. Apoptosis induced by morusin was characterized by accumulation of cells at the sub-G(1) phase, fragmentation of DNA, and condensation of chromatin. Morusin also inhibited the phosphorylation of IKK-alpha, IKK-beta and IkappaB-alpha, increased expression of IkappaB-alpha, and suppressed nuclear translocation of NF-kappaB and its DNA binding activity. Dephosphorylation of NF-kappaB upstream regulators PI3K, Akt and PDK1 was also displayed. In addition, activation of caspase-8, change of mitochondrial membrane potential, release of cytochrome c and Smac/DIABLO, and activation of caspase-9 and -3 were observed at the early time point. Downregulation in the expression of Ku70 and XIAP was exhibited afterward. Caspase-8 or wide-ranging caspase inhibitor suppressed morusin-induced apoptosis. Therefore, the antitumor mechanism of morusin in HT-29 cells may be via activation of caspases and inhibition of NF-kappaB.
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PMID:Morusin induces apoptosis and suppresses NF-kappaB activity in human colorectal cancer HT-29 cells. 1848 77

cAMP regulates a wide range of processes through its downstream effectors including PKA, and the family of guanine nucleotide exchange factors. Depending on the cell type, cAMP inhibits or stimulates growth and proliferation in a PKA-dependent or independent manner. PKA-independent effects are mediated by PI 3-kinases-Akt signaling and EPAC1 (exchange protein directly activated by cAMP) activation. Recently, we reported PKA-independent activation of the protein kinase Akt as well co-immunoprecipitation of Epac1 with Rap1, p-Akt(Thr-308), and p-Akt(Ser-473) in forskolin-stimulated macrophages. To further probe the role of Epac1 in Akt protein kinase activation and cellular proliferation, we employed the cAMP analog 8-CPT-2-O-Me-cAMP, which selectively binds to Epac1 and triggers Epac1 signaling. We show the association of Epac1 with activated Akt kinases by co-immunoprecipitation and GST-pulldown assays. Silencing Epac1 gene expression by RNA interference significantly reduced levels of Epac1 mRNA, Epac protein, Rap1 GTP, p-ERK1/2, p-B-Raf, p110alpha catalytic subunit of PI 3-kinase, p-PDK, and p-p(70s6k). Silencing Epac1 gene expression by RNA interference also suppressed 8-CPT-2-O-Me-cAMP-upregulated protein and DNA synthesis. Concomitantly, 8-CPT-2-O-Me-cAMP-mediated upregulation of Akt(Thr-308) protein kinase activity and p-Akt(Thr-308) levels was prevented in plasma membranes and nuclei of the cells. In contrast, silencing Epac1 gene expression reduced Akt(Ser-473) kinase activity and p-Akt(Ser-473) levels in plasma membranes, but showed negligible effects on nuclear activity. In conclusion, we show that cAMP-induced Akt kinase activation and cellular proliferation is mediated by Epac1 which appears to function as an accessory protein for Akt activation.
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PMID:The cAMP-activated GTP exchange factor, Epac1 upregulates plasma membrane and nuclear Akt kinase activities in 8-CPT-2-O-Me-cAMP-stimulated macrophages: Gene silencing of the cAMP-activated GTP exchange Epac1 prevents 8-CPT-2-O-Me-cAMP activation of Akt activity in macrophages. 1849 29

High altitude hypoxia is a paraphysiological condition triggering redox status disturbances of cell organization leading, via oxidative stress, to proteins, lipids, and DNA damage. In man, skeletal muscle, after prolonged exposure to hypoxia, undergoes mass reduction and alterations at the cellular level featuring a reduction of mitochondrial volume density, accumulation of lipofuscin, a product of lipid peroxidation, and dysregulation of enzymes whose time course is unknown. The effects of 7-9 days exposure to 4559 m (Margherita Hut, Monte Rosa, Italy) on the muscle proteins pattern were investigated, pre- and post-exposure, in ten young subjects, by 2-D DIGE and MS. Ten milligram biopsies were obtained from the mid part of the vastus lateralis muscle at sea level (control) and at altitude, after 7-9 days hypoxia. Differential analysis indicates that proteins involved in iron transport, tricarboxylic acid (TCA) cycle, oxidative phosphorylation, and oxidative stress responses were significantly (p<0.05) decreased in hypoxia. Parenthetically, hypoxia markers such as hypoxia inducible factor 1 alpha (HIF-1alpha) and pyruvate dehydrogenase kinase 1 (PDK1) were still at the pre-hypoxia levels, whereas the mammalian target of rapamycin (mTOR), a marker of protein synthesis, was reduced.
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PMID:Proteins modulation in human skeletal muscle in the early phase of adaptation to hypobaric hypoxia. 1893 52

Although PDK1 regulates several signaling pathways that respond to neurotrophins, direct evidence for its involvement in neurotrophin-mediated survival has not yet been reported. Here we show high neuronal expression of active PDK1 in the rat cortex and hippocampus at the developmental stages with pronounced dependence on extracellular survival signals. Also, in cultured cortical neurons from newborn rats, BDNF resulted in PDK1- and extracellular signal-regulated kinase-1/2 (ERK1/2)-mediated activation of their direct target, the p90 ribosomal S6 kinase 1/2 (RSK1/2). In trophic-deprived cortical neurons, knockdown of endogenous PDK1 attenuated the antiapoptotic survival response to 10 ng/ml BDNF, whereas an overexpressed active mutant form of PDK1 reduced apoptosis. The neuroprotection by BDNF or active PDK1 required RSK1/2. Conversely, PDK1 knockdown reversed the survival effects of combining the overexpressed RSK1 with a low, subprotective BDNF concentration of 2 ng/ml. Likewise, the protection by the overexpressed, active PDK1 was enhanced by coexpression of an active RSK1 mutant. Consistent with the observations that in BDNF-stimulated neurons RSK1/2 activation required both PDK1 and ERK1/2, ERK1/2 knockdown removed BDNF-mediated survival. Selective activation of ERK1/2 with an overexpressed active mutant form of MKK1 resulted in RSK1/2- and PDK1-dependent neuroprotection. Finally, at subprotective plasmid DNA dosage, overexpression of the active MKK1 and PDK1 mutants produced synergistic effect on survival. Our findings indicate a critical role for PDK1-RSK1/2 signaling in BDNF-mediated neuronal survival. Thus, the PDK1 is indispensable for the antiapoptotic effects of the ERK1/2 pathway offering previously unrecognized layer of survival signal processing and integration.
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PMID:Requirement of 3-phosphoinositide-dependent protein kinase-1 for BDNF-mediated neuronal survival. 1897 83

Statins are used clinically for cholesterol reduction, but statin therapy is associated with myopathic changes through a poorly defined mechanism. We used an in vivo model of statin myopathy to determine whether statins up-regulate genes associated with proteasomal- and lysosomal-mediated proteolysis and whether PDK gene expression is simultaneously up-regulated leading to the impairment of muscle carbohydrate oxidation. Animals were dosed daily with 80 mg kg(-1) day(-1) simvastatin for 4 (n = 6) and 12 days (n = 5), 88 mg kg(-1) day(-1) simvastatin for 12 days (n = 4), or vehicle (0.5% w/v hydroxypropyl-methylcellulose and 0.1% w/v polysorbate 80; Control, n = 6) for 12 days by oral gavage. We found, in biceps femoris muscle, decreased Akt(Ser473), FOXO1(Ser253) and FOXO3a(Ser253) phosphorylation in the cytosol (P < 0.05, P < 0.05, P < 0.001, respectively) and decreased phosphorylation of FOXO1 in the nucleus after 12 days simvastatin when compared to Control (P < 0.05). This was paralleled by a marked increase in the transcription of downstream targets of FOXO, i.e. MAFbx (P < 0.001), MuRF-1 (P < 0.001), cathepsin-L (P < 0.05), PDK2 (P < 0.05) and PDK4 (P < 0.05). These changes were accompanied by increased PPARalpha (P < 0.05), TNFalpha (P < 0.01), IL6 (P < 0.01), Mt1A (P < 0.01) mRNA and increased muscle glycogen (P < 0.05) compared to Control. RhoA activity decreased after 4 days simvastatin (P < 0.05); however, activity was no different from Control after 12 days. Simvastatin down-regulated PI3k/Akt signalling, independently of RhoA, and up-regulated FOXO transcription factors and downstream gene targets known to be implicated in proteasomal- and lysosomal-mediated muscle proteolysis, carbohydrate oxidation, oxidative stress and inflammation in an in vivo model of statin-induced myopathy. These changes occurred in the main before evidence of extensive myopathy or a decline in the muscle protein to DNA ratio.
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PMID:Blunted Akt/FOXO signalling and activation of genes controlling atrophy and fuel use in statin myopathy. 1911 78

Loss of fat mass in cancer cachexia is linked to increased adipocyte lipolysis; however, the fate of the excess fatty acids (FA) generated by lipolysis is not known. We investigated if the adipocyte-specific gene cell death-inducing DNA fragmentation factor-alpha-like effector A (CIDEA) could be involved. CIDEA mRNA expression was assessed in s.c. white adipose tissue from 23 cancer cachexia patients, 17 weight-stable cancer patients, and 8 noncancer patients. CIDEA was also overexpressed in adipocytes in vitro. CIDEA expression was increased in cancer cachexia (P < 0.05) and correlated with elevated levels of FAs and reported weight loss (P < 0.001). CIDEA overexpression in vitro increased FA oxidation 2- to 4-fold (P < 0.01), decreased glucose oxidation by 40% (P < 0.01), increased the expression of pyruvate dehydrogenase kinase (PDK) 1 and PDK4 (P < 0.01), and enhanced the phosphorylation (inactivation) of the pyruvate dehydrogenase complex (PDC). Inactivation of PDC facilitates FA oxidation by favoring the metabolism of FAs over glucose to acetyl-CoA. In accordance with the in vitro data, PDK1 and PDK4 expression correlated strongly with CIDEA expression in white adipose tissue (P < 0.001). We conclude that CIDEA is involved in adipose tissue loss in cancer cachexia and this may, at least in part, be due to its ability to inactivate PDC, thereby switching substrate oxidation in human fat cells from glucose to FAs.
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PMID:Evidence for an important role of CIDEA in human cancer cachexia. 1901 Aug 97

It is known that the concentration and activity of the DNA precursor enzyme thymidine kinase 1 (TK1) in serum is significantly elevated in patients with malignancies, as compared with levels in patients with benign tumours and those in healthy individuals. For the first time, the use of serum TK1 as a prognostic marker for patients with renal cell carcinoma (RCC) was examined. Serum TK1 protein (STK1p) concentration and serum TK1 activity (STK1a) were determined by a dot blot chemoluminescence assay and a radio enzyme assay, respectively. There was no correlation between STK1p and STK1a in the same sera from 27 RCC patients. Only one STK1p value as compared with 15 STK1a values was clearly above the cut-off values (2 pmol/l and 6 U/l, respectively) for healthy individuals. STK1a values did not correlate with the level of TK1 expression in tumour sections from the RCC patients, estimated by immunohistochemistry staining. However, there was a significant correlation between STK1a levels and the grade, stage and size of the RCC tumours. The discrepancy between the STK1p and the STK1a results is likely to be because of reduced ability of the TK1 antibody to recognize the STK1 in sera from RCC patients. We conclude that the activity of STK1 is a useful tool for evaluating the prognosis of patients with RCC.
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PMID:Thymidine kinase activity in serum of renal cell carcinoma patients is a useful prognostic marker. 1928 58

Aging is a biological process that is characterized by the gradual loss of physiological function and increases in the susceptibility to disease of an individual. During the aging process, a wide spectrum of alterations in mitochondria and mitochondrial DNA (mtDNA) has been observed in somatic tissues of humans and animals. This is associated with the decline in mitochondrial respiratory function; excess production of the reactive oxygen species (ROS); increase in the oxidative damage to mtDNA, lipids and proteins in mitochondria; accumulation of point mutations and large-scale deletions of mtDNA; and altered expression of genes involved in intermediary metabolism. It has been demonstrated that the ROS may cause oxidative damage and mutations of mtDNA and alterations of the expression of several clusters of genes in aging tissues and senescent cells. We found that intracellular levels of hydrogen peroxide (H2O2) and oxidative damage to DNA in the tissue cells and skin fibroblasts of old donors were higher than those of young donors. In H2O2-induced senescent skin fibroblasts, we observed an increase in the protein expression and activity levels of manganese-dependent superoxide dismutase and a concurrent decrease in the activity of cytochrome c oxidase and the rate of oxygen consumption. Moreover, the mRNA and protein expression levels of pyruvate dehydrogenase (PDH) were decreased but those of PDH kinase and lactate dehydrogenase were increased in senescent skin fibroblasts. The changes in the expression of these enzymes suggest a metabolic shift from mitochondrial respiration to glycolysis as a major supply of ATP in aging human cells. On the other hand, recent studies on mitochondrial mutant mice, which carry a proofreading deficient subunit of DNA polymerase gamma, revealed that mtDNA mutations accumulated in somatic tissues in the mice that displayed prominent features of aging. Taken together, we suggest that the respiratory function decline and increase in the production of the ROS in mitochondria, accumulation of mtDNA mutation and oxidative damage, and altered expression of a few clusters of genes that culminated in the metabolic shift from mitochondrial respiration to glycolysis for major supply of ATP were key contributory factors in the aging process in the human and animals.
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PMID:Respiratory function decline and DNA mutation in mitochondria, oxidative stress and altered gene expression during aging. 1940 1


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