Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.2 (PDK1)
 2,238 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The specificities of pyruvate dehydrogenase kinase and pyruvate dehydrogenase phosphatase were probed using synthetic peptides corresponding to the sequence around phosphorylation sites 1 and 2 on pyruvate dehydrogenase [Tyr-His-Gly-His-Ser(P1)-Met-Ser-Asp-Pro-Gly-Val-Ser(P2)-Tyr-Arg]. The dephosphotetradecapeptide containing aspartic acid at position 8 was a better substrate for the kinase than was the tetradecapeptide containing asparagine at position 8. The apparent Km and V values for the two peptides were 0.43 and 6.1 mM and 2.7 and 2.4 nmol of 32P incorporated/min/mg, respectively. Methylation of the aspartic acid residue also increased the apparent Km of the tetradecapeptide about 14-fold. These results indicate that an acidic residue on the carboxyl-terminal side of phosphorylation site 1 is an important specificity determinant for the kinase. Phosphate was incorporated only into site 1 of the synthetic peptide by the kinase. The phosphatase exhibited an apparent Km of 0.28 mM and a V of 2.3 mumol of 32P released/min/mg for the phosphorylated tetradecapeptide containing aspartic acid. Methylation of the aspartic acid residue had no significant effect on dephosphorylation. The octapeptide and phosphooctapeptide produced by cleavage of the aspartyl-prolyl bond by formic acid were poorer substrates for the kinase and phosphatase than were the tetradecapeptide and phosphotetradecapeptide, respectively. Modification of the amino terminal by acetylation or lysine addition had only a slight effect on the kinase and phosphatase activities.
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PMID:Synthetic peptide substrates for mammalian pyruvate dehydrogenase kinase and pyruvate dehydrogenase phosphatase. 300 77

The serum- and glucocorticoid-inducible kinase 1 (SGK1) is a key regulator of osteo-/chondrogenic transdifferentiation and subsequent calcification of vascular smooth muscle cells (VSMCs). The phenotypical transdifferentiation of VSMCs is associated with increased interleukin-18 (IL-18) levels and generalized inflammation. Therefore, the present study investigated the possible involvement of SGK1 in IL-18-induced vascular calcification. Experiments were performed in primary human aortic smooth muscle cells (HAoSMCs) treated with recombinant human IL-18 protein in control or high phosphate conditions and following SGK1 knockdown by siRNA or pharmacological inhibition of SGK1, PI3K, and PDK1. As a result, IL-18 treatment increased SGK1 mRNA and protein expression in HAoSMCs. IL-18 upregulated SGK1 mRNA expression in a dose-dependent manner. This effect was paralleled by upregulation of the mRNA expression of MSX2 and CBFA1, osteogenic transcription factors, and of tissue-nonspecific alkaline phosphatase (ALPL), an osteogenic enzyme, as markers of increased osteo-/chondrogenic transdifferentiation. Phosphate treatment increased SGK1 and osteogenic markers mRNA expression as well as ALPL activity and induced calcification of HAoSMCs, all effects significantly augmented by additional treatment with IL-18. Conversely, silencing of SGK1 or cotreatment with the SGK1 inhibitor EMD638683 blunted the effects of IL-18 on osteo-/chondrogenic transdifferentiation and calcification of HAoSMCs. The procalcific effects of IL-18 were similarly suppressed in the presence of PI3K or PDK1 inhibitors. In conclusion, SGK1 expression is upregulated by IL-18 in VSMCs and SGK1 participates in the intracellular signaling of IL-18-induced osteo-/chondrogenic transdifferentiation of VSMCs. Thus, SGK1 may serve as therapeutic target to limit the progression of medial vascular calcification during vascular inflammation.
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PMID:SGK1-dependent stimulation of vascular smooth muscle cell osteo-/chondrogenic transdifferentiation by interleukin-18. 3070 78