scholarly journals Calmodulin inhibits the protein kinase C-catalysed phosphorylation of an endogenous protein in A10 smooth-muscle cells

1991 ◽  
Vol 277 (2) ◽  
pp. 445-450 ◽  
Author(s):  
D Y Zhao ◽  
M D Hollenberg ◽  
D L Severson
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Inhibitory Effect ◽  
Kinase C ◽  
Direct Inhibitory Effect ◽  
Ic50 Values

The protein kinase C (PKC) activator phorbol 12,13-dibutyrate stimulated the phosphorylation of a 75 kDa protein (p75) in intact cultured A10 smooth-muscle cells and sonicated cell preparations; p75 was the only major substrate for endogenous PKC in sonicated A10 cells. The Ca(2+)-dependent phosphorylation of p75 in vitro was dramatically decreased in PKC-down-regulated A10 cells; however, p75 from identical sonicated cell preparations was still phosphorylated by an exogenous aortic PKC preparation. Calmodulin inhibited the phosphorylation of p75 by PKC, but not the phosphorylation of other PKC substrates (platelet P47 protein and histone). The addition of calmodulin after the phosphorylation reaction was started prevented further phosphorylation, but did not decrease the extent of phosphorylation of p75 that was reached before the addition of calmodulin. The inhibition of p75 phosphorylation was concentration-dependent, with IC50 values (concn. giving 50% inhibition) ranging from less than 0.5 to 10 micrograms of calmodulin/ml, and was Ca(2+)-dependent, requiring a free Ca2+ concentration of 10 microM or greater. These results suggest that the inhibition of the PKC-catalysed phosphorylation of p75 by calmodulin may be due to its interaction with the substrate, rather than a direct inhibitory effect on the enzyme, and that this inhibition could be regulated by intracellular Ca2+ concentration. Therefore, p75 may be a physiological link between the PKC and Ca2+/calmodulin pathways.

scholarly journals α-Tocopherol specifically inactivates cellular protein kinase C α by changing its phosphorylation state

1998 ◽  
Vol 334 (1) ◽  
pp. 243-249 ◽  
Author(s):  
Roberta RICCIARELLI ◽  
Andrea TASINATO ◽  
Sophie CLÉMENT ◽  
Nesrin K. ÖZER ◽  
Daniel BOSCOBOINIK ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Smooth Muscle Cells ◽  
Protein Phosphatase ◽  
Antioxidant Properties ◽  
Muscle Cells ◽  
Cellular Protein ◽  
Kinase C

The mechanism of protein kinase C (PKC) regulation by α-tocopherol has been investigated in smooth-muscle cells. Treatment of rat aortic A7r5 smooth-muscle cells with α-tocopherol resulted in a time- and dose-dependent inhibition of PKC. The inhibition was not related to a direct interaction of α-tocopherol with the enzyme nor with a diminution of its expression. Western analysis demonstrated the presence of PKCα, β, δ, ε, ζ and µ isoforms in these cells. Autophosphorylation and kinase activities of the different isoforms have shown that only PKCα was inhibited by α-tocopherol. The inhibitory effects were not mimicked by β-tocopherol, an analogue of α-tocopherol with similar antioxidant properties. The inhibition of PKCα by α-tocopherol has been found to be associated with its dephosphorylation. Moreover the finding of an activation of protein phosphatase type 2A in vitro by α-tocopherol suggests that this enzyme might be responsible for the observed dephosphorylation and subsequent deactivation of PKCα. It is therefore proposed that PKCα inhibition by α-tocopherol is linked to the activation of a protein phosphatase, which in turn dephosphorylates PKCα and inhibits its activity.

Regulation of Scavenger Receptor Expression in Smooth Muscle Cells by Protein Kinase C

1997 ◽  
Vol 17 (5) ◽  
pp. 969-978 ◽  
Author(s):  
Michele Mietus-Snyder ◽  
Annabelle Friera ◽  
Christopher K. Glass ◽  
Robert E. Pitas
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Smooth Muscle Cells ◽  
Scavenger Receptor ◽  
Muscle Cells ◽  
Receptor Expression ◽  
Kinase C

Antiproliferative action of protein kinase C in cultured rabbit aortic smooth muscle cells

1987 ◽  
Vol 173 (2) ◽  
pp. 504-514 ◽  
Author(s):  
Ken-Ichi Kariya ◽  
Yasuo Fukumoto ◽  
Terutaka Tsuda ◽  
Takeshi Yamamoto ◽  
Yasuhiro Kawahara ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Aortic Smooth Muscle Cells ◽  
Aortic Smooth Muscle ◽  
Kinase C ◽  
Antiproliferative Action

scholarly journals Minimally Modified LDL Upregulates Endothelin Type A Receptors in Rat Coronary Arterial Smooth Muscle Cells

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Jie Li ◽  
Lei Cao ◽  
Cang-Bao Xu ◽  
Jun-Jie Wang ◽  
Yong-Xiao Cao
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Smooth Muscle Cells ◽  
Coronary Arteries ◽  
Muscle Cells ◽  
Type A ◽  
Receptor Mrna ◽  
Kinase C ◽  
Arterial Smooth Muscle Cells

Minimally modified low-density lipoprotein (mmLDL) is a risk factor for cardiovascular disease. The present study investigated the effects of mmLDL on the expression of endothelin type A () receptors in coronary arteries. Rat coronary arteries were organ-cultured for 24 h. The contractile responses were recorded using a myographic system. receptor mRNA and protein expressions were determined using real-time PCR and western blotting, respectively. The results showed that organ-culturing in the presence of mmLDL enhanced the arterial contractility mediated by the receptor in a concentration-dependent and time-dependent manner. Culturing with mmLDL (10 μg/mL) for 24 h shifted the concentration-contractile curves toward the left significantly with increased of from control of and significantly increased receptor mRNA and protein levels. Inhibition of the protein kinase C, extracellular signal-related kinases 1 and 2 (ERK1/2), or NF-κB activities significantly attenuated the effects of mmLDL. The c-Jun N-terminal kinase inhibitor or the p38 pathway inhibitor, however, had no such effects. The results indicate that mmLDL upregulates the receptors in rat coronary arterial smooth muscle cells mainlyviaactivating protein kinase C, ERK1/2, and the downstream transcriptional factor, NF-κB.

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