AJP - Cell Physiology, Vol 270, Issue 1 C286-C292, Copyright © 1996 by American Physiological Society
Role of phosphodiesterase II in cross talk between cGMP and cAMP in human neuroblastoma NB-OK-1 cells
C. Delporte, P. Poloczek and J. Winand
Department of Biochemistry and Nutrition, Medical School, Universite Libre de Bruxelles, Belgium.
Cyclic nucleotides levels and cyclic nucleotide phosphodiesterase (PDE)
activities were measured in human neuroblastoma NB-OK-1 cells possessing
atrial natriuretic peptide (ANP) receptors of the A type and pituitary
adenylate cyclase activating polypeptide (PACAP)-preferring receptors.
Adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic
monophosphate (cGMP) degradation were interrelated since the increase in
cGMP, induced by ANP-(99-126), stimulated the hydrolysis of cAMP by PDE
isoenzyme II. In intact NB-OK-1 cells, the levels of cAMP and cGMP attained
in the presence of, respectively, 1 nM PACAP-(1-27) and 10 nM ANP-(99-126),
and in the absence or presence of PDE inhibitors, strongly suggested that
cAMP hydrolysis was mainly achieved by isoenzyme IV, and to a lesser extent
by isoenzymes I, II, and III, while cGMP was degraded by isoenzymes I, II,
III, and V. More than one-half of total cAMP- and cGMP-hydrolyzing
activities was present in the membrane-bound fraction. Cyclic nucleotide
PDE activities separated by anion-exchange chromatography showed that
isoenzymes III and IV were mainly present in the membrane fraction, while
isoenzymes I, II, and V were in the cytosolic fraction.
