scholarly journals Death-Associated Protein Kinase Phosphorylates Mammalian Ribosomal Protein S6 and Reduces Protein Synthesis†

Biochemistry ◽  
2006 ◽  
Vol 45 (45) ◽  
pp. 13614-13621 ◽  
Author(s):  
Andrew M. Schumacher ◽  
Anastasia V. Velentza ◽  
D. Martin Watterson ◽  
John Dresios
Keyword(s):  
Protein Synthesis ◽  
Protein Kinase ◽  
Ribosomal Protein ◽  
Ribosomal Protein S6 ◽  
Death Associated Protein Kinase

Protein kinase activity and ribosome phosphorylation in ethionine-treated rats

1979 ◽  
Vol 57 (3) ◽  
pp. 209-215 ◽  
Author(s):  
Margaret A. Treloar ◽  
Robert Kisilevsky
Keyword(s):  
Protein Synthesis ◽  
Protein Kinase ◽  
Ribosomal Protein ◽  
Kinase Activity ◽  
Synthetic Activity ◽  
Clear Correlation ◽  
Protein Kinase Activity ◽  
Phosphoprotein Phosphatase ◽  
Ribosomal Protein S6

The regulation of protein synthesis at the level of the ribosome was investigated using the model system of ethionine-induced inhibition of protein synthesis. The phosphorylation of ribosomal protein S6 was examined in vivo during ethionine intoxication and during the adenine-induced reversal of ethionine intoxication. The extent of phosphorylation of S6 correlated well with protein synthetic activity observed after ethionine, and ethionine followed by adenine treatments. No clear correlation was observed in the ethionine system between cyclic adenosine 3′:5′-monophosphate concentration or the activity of ribosomal protein kinase and the phosphorylation of ribosomal protein S6. A role for a cyclic adenosine 3′:5′-monophosphate-dependent ribosomal phosphoprotein phosphatase is postulated.

scholarly journals Ca2+-independent protein kinase C activity is required for alpha1-adrenergic-receptor-mediated regulation of ribosomal protein S6 kinases in adult cardiomyocytes

2003 ◽  
Vol 373 (2) ◽  
pp. 603-611 ◽  
Author(s):  
Lijun WANG ◽  
Mark ROLFE ◽  
Christopher G. PROUD
Keyword(s):  
Protein Synthesis ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Ribosomal Protein ◽  
Adrenergic Receptor ◽  
Rat Cardiomyocytes ◽  
Ribosomal Protein S6 ◽  
Kinase C ◽  
Adult Cardiomyocytes ◽  
Pkc Isoforms

The α1-adrenergic agonist, phenylephrine (PE), exerts hypertrophic effects in the myocardium and activates protein synthesis. Both Ca2+-dependent protein kinase C (PKC, PKCα) and Ca2+-independent PKC isoforms (PKCδ and ε) are detectably expressed in adult rat cardiomyocytes. Stimulation of the α1-adrenergic receptor by PE results in activation of Ca2+-independent PKCs, as demonstrated by translocation of the δ and ε isoenzymes from cytosol to membrane fractions. PE also induces activation of p70 ribosomal protein S6 kinases (S6K1 and 2) in adult cardiomyocytes. We have studied the role of Ca2+-independent PKCs in the regulation of S6K activity by PE. Activation of S6K1/2 by PE was blocked by the broad-spectrum PKC inhibitor bisindolylmaleimide (BIM) I, whereas Gö6976, a compound that only inhibits Ca2+-dependent PKCs, did not inhibit S6K activation. Rottlerin, which selectively inhibits PKCδ, also prevented PE-induced S6K activation. The isoform-specific PKC inhibitors had similar effects on the phosphorylation of eukaryotic initiation factor 4E (eIF4E)-binding protein 1, a translation repressor that, like the S6Ks, lies downstream of the mammalian target of rapamycin (mTOR). Infection of cells with adenoviruses encoding dominant-negative PKCδ or ε inhibited the activation of extracellular-signal-regulated kinase (ERK) by PE, and also inhibited the activation and/or phosphorylation of S6Ks 1 and 2. The PE-induced activation of protein synthesis was abolished by BIM I and markedly attenuated by rottlerin. Our data thus suggest that Ca2+-independent PKC isoforms play an important role in coupling the α1-adrenergic receptor to mTOR signalling and protein synthesis in adult cardiomyocytes.

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