In vitro PKA phosphorylation-mediated human PDE4A4 activation.
The PDE4 catalytic machinery comprises, in part, two divalent cations in a binuclear motif. Here we report that PDE4A4 expressed in Sf9 cells exhibits a biphasic Mg(2+) dose-response (EC(50) of 0.15 and >10 mM) in catalyzing cAMP hydrolysis. In vitro phosphorylation of PDE4A4 by the PKA-catalytic subunit increases the enzyme's sensitivity to Mg(2+), leading to 4-fold increased cAMP hydrolysis without affecting its K(m). The phosphorylation also increases the potencies of (R)- and (S)-rolipram without affecting CDP-840 and SB-207499. The results support that modulating the cofactor binding affinity of PDE4 represents a mechanism for regulating its activity.
Laliberté
France
F
Department of Biochemistry and Molecular Biology, Merck Frosst Centre for Therapeutical Research, P.O. Box 1005, Pointe Claire, H9R4P8, Dorval, QC, Canada.
Liu
Susana
S
Gorseth
Elise
E
Bobechko
Brian
B
Bartlett
Adrienne
A
Lario
Paula
P
Gresser
Michael J
MJ
Huang
Zheng
Z
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism*; D002413:Cations, Divalent / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D004789:Enzyme Activation; D006801:Humans; D008274:Magnesium / Q000494:pharmacology; D010766:Phosphorylation
D002413:Cations, Divalent; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D008274:Magnesium