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)

Previous studies have demonstrated that pyruvate dehydrogenase kinase (PDHK) activity in extracts of rat cardiac mitochondria is increased @two-fold by providing a high-fat diet for 28 days. The present study sought to establish the factor(s) that might underlie the response of cardiac PDHK to the provision of a high-fat diet. ELISA assays of PDHKII, conducted over a range of PDHK activities, demonstrated that the increase in cardiac PDHK activity was not due to an increase in mitochondrial immunoreactive PDHKII concentration. The pyruvate concentration giving 50% active PDHC (PDHa) in mitochondria incubated with respiratory substrates was unaffected by high-fat feeding, demonstrating a dissociation between increased PDHK activity and altered sensitivity of PDHK to suppression by pyruvate. In cardiac myocytes cultured (25 h) with n-octanoate (1 mm) plus dibutyryl cAMP (50 microM), insulin at 12.5 microU/ml, 25 microU/ml and 75 microU/ml, suppressed PDHK activities in cells prepared from control rats, but insulin at concentrations <100 microU/ml failed to suppress PDHK activities in cardiac myocytes prepared from high-fat-fed rats. In vivo, cardiac insulin sensitivity (assessed by euglycaemic hyperinsulinaemic clamp in combination with 2-[3H] deoxyglucose administration) was suppressed after high-fat feeding. A sustained (24 h) two- to four-fold elevation in plasma insulin concentration (achieved by insulin infusion via osmotic pumps) did not affect PDHK activity in hearts of control rats. In contrast, PDHK activity in hearts of high-fat-fed rats was suppressed to values not significantly different from (insulin-infused) control rats. Basal and agonist-stimulated cAMP concentrations were unaffected by high-fat-feeding or insulin. Furthermore, rates of palmitate oxidation (to CO2) in cardiac myocytes (in the absence or presence of insulin or adrenergic agonists) were not statistically significantly affected by high-fat-feeding. The results indicate that an impaired action of insulin to suppress PDHK participates in the mechanism by which increased PDHK activity is achieved in response to high-fat feeding, but insulin does not act through decreasing cAMP concentrations or suppressing fatty acid oxidation.
J Mol Cell Cardiol 1997 Jul
PMID:Molecular mechanisms underlying the long-term impact of dietary fat to increase cardiac pyruvate dehydrogenase kinase: regulation by insulin, cyclic AMP and pyruvate. 923 40

Oxidative metabolism of glucose is regulated by pyruvate dehydrogenase (PDH) that can be inhibited by isoforms of PDH kinase (PDK). Recently, increased PDK activity has been implicated in the pathogenesis of insulin resistance and non-insulin-dependent diabetes mellitus (NIDDM) in obese subjects. Using quantitative RT-PCR, we measured mRNA of PDK2 and PDK4 isoforms in skeletal muscle biopsies from nondiabetic Pima Indians, a population with a high prevalence of NIDDM associated with obesity. PDK2 and PDK4 mRNAs were positively correlated with fasting plasma insulin concentration, 2-h plasma insulin concentration in response to oral glucose, and percentage body fat, whereas both isoforms were negatively correlated with insulin-mediated glucose uptake rates. Measurements of PDK2 and PDK4 mRNA during the hyperinsulinemic-euglycemic clamp and of PDK2 in cell culture indicated that both transcripts decrease in response to insulin. Increased fatty acid (FA) oxidation has been traditionally viewed as the cause for increased PDK activity contributing to insulin resistance in obese subjects. In contrast, our data indicate that insufficient downregulation of PDK mRNA in insulin-resistant individuals could be a cause of increased PDK expression leading to impaired glucose oxidation followed by increased FA oxidation.
Mol Genet Metab 1998 Oct
PMID:Insulin downregulates pyruvate dehydrogenase kinase (PDK) mRNA: potential mechanism contributing to increased lipid oxidation in insulin-resistant subjects. 978 10

Fission yeast (Schizosaccharomyces pombe) requires inositol for growth, mating and sporulation. To define putative genes that are involved in the processing and transduction of the inositol signal, mutants that are temperature sensitive for growth and sporulation were selected on a medium containing non-limiting amounts of inositol. Two such mutants (ksg1-208 and ksg1-358) were analyzed, which are impaired in mating and sporulation at 30 degrees C and undergo growth arrest in the G2 phase of the cell cycle at 35 degrees C. The ksg1 gene was isolated by functional complementation. It maps on the left arm of chromosome II and encodes a putative 592-amino acid protein which exhibits good structural homology to a human 3-phosphoinositide-dependent protein kinase (PDK1) and its rat and Drosophila homologues. The two mutants have the same substitution at amino acid position 159: a glycine residue is replaced by glutamic acid. Deletion of the gene is lethal for haploid cells. We propose that ksg1 is involved in one or several phosphoinositide signalling processes that are responsible for control of the life cycle.
Mol Gen Genet 1999 Feb
PMID:A Schizosaccharomyces pombe gene, ksg1, that shows structural homology to the human phosphoinositide-dependent protein kinase PDK1, is essential for growth, mating and sporulation. 1007 Dec 24

p70 S6 kinase (p70S6K) is an important regulator of cell proliferation. Its activation by growth factor requires phosphorylation by various inputs on multiple sites. Data accumulated thus far support a model whereby p70S6K activation requires sequential phosphorylations at proline-directed residues in the putative autoinhibitory pseudosubstrate domain, as well as threonine 389. Threonine 229, a site in the catalytic loop is phosphorylated by phosphoinositide-dependent kinase 1 (PDK-1). Experimental evidence suggests that p70S6K activation requires a phosphoinositide 3-kinase (PI3-K)-dependent signal(s). However, the intermediates between PI3-K and p70S6K remain unclear. Here, we have identified PI3-K-regulated atypical protein kinase C (PKC) isoform PKCzeta as an upstream regulator of p70S6K. In coexpression experiments, we found that a kinase-inactive PKCzeta mutant antagonized activation of p70S6K by epidermal growth factor, PDK-1, and activated Cdc42 and PI3-K. While overexpression of a constitutively active PKCzeta mutant (myristoylated PKCzeta [myr-PKCzeta]) only modestly activated p70S6K, this mutant cooperated with PDK-1 activation of p70S6K. PDK-1-induced activation of a C-terminal truncation mutant of p70S6K was also enhanced by myr-PKCzeta. Moreover, we have found that p70S6K can associate with both PDK-1 and PKCzeta in vivo in a growth factor-independent manner, while PDK-1 and PKCzeta can also associate with each other, suggesting the existence of a multimeric PI3-K signalling complex. This work provides evidence for a link between a phorbol ester-insensitive PKC isoform and p70S6K. The existence of a PI3-K-dependent signalling complex may enable efficient activation of p70S6K in cells.
Mol Cell Biol 1999 Apr
PMID:p70 S6 kinase is regulated by protein kinase Czeta and participates in a phosphoinositide 3-kinase-regulated signalling complex. 1008 59

Chronic sepsis promotes a stable increase in pyruvate dehydrogenase kinase (PDHK) activity in skeletal muscle. PDHK is found tightly bound to the pyruvate dehydrogenase (PDH) complex and as free kinase. We investigated the ability of sepsis to modify the activity of the PDHK intrinsic to the PDH and free PDHK. Sepsis was induced by the intraabdominal introduction of a fecal-agar pellet infected with E. coli and B. fragilis. Five days later, mitochondria were isolated from skeletal muscle and PDHK measured in mitochondrial extracts. Sepsis caused an approximate 2-fold stimulation of PDHK. The mitochondrial extracts from control and septic rats were fractionated by gel chromatography on Sephacryl S-300 to separate PDHK intrinsic to PDH complex and free PDHK. PDH complex eluted at void volume and was assayed for PDHK intrinsic to the complex. The activity of PDHK intrinsic to PDH complex was a significantly increased 3 fold during sepsis. Free PDHK activity eluted after the PDH complex and its activity was enhanced by 70% during sepsis. Incubation of PDHK intrinsic to PDH with dichloroactate, an uncompetitive inhibitor of PDHK, showed the PDHK from septic rats relatively less sensitive to inhibition than controls. These results indicate that sepsis induces stable changes in PDHK in skeletal muscle.
Mol Cell Biochem 1999 Aug
PMID:Sepsis alters pyruvate dehydrogenase kinase activity in skeletal muscle. 1049 85

PDK1 (phosphoinositide-dependent kinase 1) is a mammalian growth factor-regulated serine/threonine kinase. Using a genetic selection based on a mutant form of the yeast MAP kinase kinase Ste7, we isolated a gene, PKH2, encoding a structurally and functionally conserved yeast homolog of PDK1. Yeast cells lacking both PKH2 and PKH1, encoding another PDK1 homolog, were nonviable, indicating that Pkh1 and Pkh2 share an essential function. A temperature-sensitive mutant, pkh1(D398G) pkh2, was phenotypically similar to mutants defective in the Pkc1-mitogen-activated protein kinase (MAPK) pathway. Genetic epistasis analyses, the phosphorylation of Pkc1 by Pkh2 in vitro, and reduced Pkc1 activity in the pkh1(D398G) pkh2 mutant indicate that Pkh functions upstream of Pkc1. The Pkh2 phosphorylation site in Pkc1 (Thr-983) is part of a conserved PDK1 target motif and essential for Pkc1 function. Thus, the yeast PDK1 homologs activate Pkc1 and the Pkc1-effector MAPK pathway.
Mol Cell Biol 1999 Dec
PMID:PDK1 homologs activate the Pkc1-mitogen-activated protein kinase pathway in yeast. 1056 59

Accumulation of ceramide has been reported in stress- and receptor-induced apoptosis in the nervous system. However, its role in apoptosis signaling remains elusive. We describe here the inhibition of the NGF-activated phosphoinositide 3-kinase (PI3K)-PKB/Akt1 survival pathway by the cell permeable analog C2-ceramide. C2-ceramide did not inhibit ERK, PI3K, or PDK1 activities and did not alter the translocation of PDK1 and Akt1 to the plasma membrane, but blocked nuclear translocation of Akt1. Down-regulation of the Akt pathway was due to enhanced dephosphorylation of Akt1 at residues T308 and S473. Moreover, Akt1 was dephosphorylated in vitro by a cation-independent phosphatase involving ceramide-activated protein phosphatase (CAPP). Membrane-anchored Akt1 was more resistant to dephosphorylation/inactivation by C2-ceramide than wild-type Akt1. Consistently, N-myristylated-Akt1 conferred resistance to the apoptosis induced by C2-ceramide in PC12 cells. These results provide a novel mechanism for induction of apoptosis by ceramide in nerve-derived cells.
Mol Cell Neurosci 2000 Feb
PMID:Inhibition of PKB/Akt1 by C2-ceramide involves activation of ceramide-activated protein phosphatase in PC12 cells. 1067 24

Pyruvate dehydrogenase kinase (PDHK), a negative regulator of the mitochondrial pyruvate dehydrogenase (PDH) complex (mtPDC), plays a pivotal role in controlling mtPDC activity, and hence, the TCA cycle and cell respiration. This report describes the cloning of a pyruvate dehydrogenase kinase cDNA (AtPDHK) from Arabidopsis thaliana and focuses on the effects of antisense down-regulation of its expression on plant growth and development. The deduced amino acid sequence of AtPDHK exhibits extensive similarity to other plant and mammalian PDHKs, containing conserved domains typical of two-component histidine protein kinases. The Escherichia coli expressed AtPDHK specifically phosphorylated mammalian PDH E1 in a time-dependent manner. Antisense expression of the AtPDHK cDNA led to marked elevation of mtPDC activity in transgenic plants with increases ranging from 137% to 330% compared to control plants. Immunoblot analyses performed with a monoclonal antibody to the E1alpha mtPDH component (the subunit phosphorylated by PDHK) indicated that the increased mtPDC activity was not the result of an increase in the level of PDH protein. MtPDC from transgenic plants showed a reduced sensitivity to ATP-dependent inactivation compared to that observed in wild-type plants. Collectively, these data suggest that the antisense partial silencing of the negative regulator, PDHK, was responsible for the increased mtPDC activity observed in the antisense PDHK plants. Transgenic plants with partially repressed AtPDHK also displayed altered vegetative growth with reduced accumulation of vegetative tissues, early flower development and shorter generation time. The potential role for AtPDHK gene manipulation in crop improvement is discussed.
Plant Mol Biol 1999 Dec
PMID:Effects of antisense repression of an Arabidopsis thaliana pyruvate dehydrogenase kinase cDNA on plant development. 1073 48

Although mitogenic and differentiating factors often activate a number of common signaling pathways, the mechanisms leading to their distinct cellular outcomes have not been elucidated. In a previous report, we demonstrated that mitogen-activated protein (MAP) kinase (ERK) activation by the neurogenic agents fibroblast growth factor (FGF) and nerve growth factor is dependent on protein kinase Cdelta (PKCdelta), whereas MAP kinase activation in response to the mitogen epidermal growth factor (EGF) is independent of PKCdelta in rat hippocampal (H19-7) and pheochromocytoma (PC12) cells. We now show that EGF activates MAP kinase through a PKCzeta-dependent pathway involving phosphatidylinositol 3-kinase and PDK1 in H19-7 cells. PKCzeta, like PKCdelta, acts upstream of MEK, and PKCzeta can potentiate Raf-1 activation by EGF. Inhibition of PKCzeta also blocks EGF-induced DNA synthesis as monitored by bromodeoxyuridine incorporation in H19-7 cells. Finally, in embryonic rat brain hippocampal cell cultures, inhibitors of PKCzeta or PKCdelta suppress MAP kinase activation by EGF or FGF, respectively, indicating that these factors activate distinct signaling pathways in primary as well as immortalized neural cells. Taken together, these results implicate different PKC isoforms as determinants of growth factor signaling specificity within the same cell. Furthermore, these data provide a mechanism whereby different growth factors can differentially activate a common signaling intermediate and thereby generate biological diversity.
Mol Cell Biol 2000 Aug
PMID:Different protein kinase C isoforms determine growth factor specificity in neuronal cells. 1089 80

The glycoprotein hormones, ACTH, TSH, FSH, and LH regulate diverse functions in endocrine cells. Although cAMP and PKA have long been shown to mediate specific intracellular signaling events including the transcription of specific genes via the CREB-CBP complex, recent observations have indicated that PKA does not account for all of the intracellular targets of cAMP. For example, TSH stimulation of thyroid cell proliferation is not completely blocked by PKA inhibitors. TSH and FSH can stimulate PKB phosphorylation by a PKAindependent but PI3-K/PDK1-dependent pathway. An FSH inducible kinase, Sgk, has recently been shown to be a close relative of PKB. Sgk is also a target of PI3-K-PDK1 pathway, indicating that some effects previously ascribed to PKB may be mediated by this inducible kinase. The identification of novel cAMP-binding proteins that exhibit guanine nucleotide exchange (GEF) activity (cAMP-GEFS; Epacs) has open new doors for cAMP action that include activation of small GTPases such as Rap1a, Rap2, and possibly Ras. These GTPases are known activators of downstream kinase cascades, including p38MAPK and Erk1/2 as well as PI3-K. Thus, FSH and TSH activation of PKB and Sgk may occur via this alternative cAMP pathway that involves cAMP-GEFs and the activation of the PI3-K/PDK1 pathway.
Mol Endocrinol 2001 Feb
PMID:New signaling pathways for hormones and cyclic adenosine 3',5'-monophosphate action in endocrine cells. 1115 28


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