scholarly journals Nitric Oxide Activation of p38 Mitogen-activated Protein Kinase in 293T Fibroblasts Requires cGMP-dependent Protein Kinase

2000 ◽  
Vol 275 (4) ◽  
pp. 2811-2816 ◽  
Author(s):  
Darren D. Browning ◽  
Marisa P. McShane ◽  
Caroline Marty ◽  
Richard D. Ye
Keyword(s):  
Nitric Oxide ◽  
Protein Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Dependent Protein Kinase ◽  
Cgmp Dependent Protein Kinase ◽  
Mitogen Activated Protein ◽  
Dependent Protein

Protein kinase A acts at multiple points to inhibit Xenopus oocyte maturation

1994 ◽  
Vol 14 (7) ◽  
pp. 4419-4426
Author(s):  
W Matten ◽  
I Daar ◽  
G F Vande Woude
Keyword(s):  
Protein Kinase ◽  
Xenopus Oocytes ◽  
Negative Regulator ◽  
Mitogen Activated Protein Kinase ◽  
Mobility Shift ◽  
Dependent Protein Kinase ◽  
Multiple Points ◽  
Mitogen Activated Protein ◽  
Dependent Protein ◽  
Phosphatase Activation

In Xenopus oocytes, initiation of maturation is dependent on reduction of cyclic AMP-dependent protein kinase (PKA) activity and the synthesis of the mos proto-oncogene product. Mos is required during meiosis I for the activation of both maturation-promoting factor (MPF) and mitogen-activated protein kinase (MAPK). Here we show that injection of the catalytic subunit of PKA (PKAc) prevented progesterone-induced synthesis of endogenous Mos as well as downstream MPF and MAPK activation. However, PKAc did not prevent injected soluble Mos product from activating MAPK. While MAPK is activated during Mos-PKAc coinjection, attendant MPF activation is blocked. Additionally, PKAc caused a potent block in the electrophoretic mobility shift of cdc25 that is associated with phosphatase activation. This inhibition of cdc25 activity was not reversed by progesterone, Mos, or MPF. We conclude that PKAc acts as a negative regulator at several points in meiotic maturation by preventing both Mos translation and MPF activation.

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