title: Isolation and regulation of the cGMP-inhibited cAMP phosphodiesterase in human erythroleukemia cells.
abstract: The predominant cAMP phosphodiesterase in human platelets is the low K(m) cGMP-inhibited phosphodiesterase (PDE 3A). We have isolated native PDE3A from platelets and human erythroleukemia (HEL) cells and studied its kinetics. The platelet and HEL cell enzymes hydrolyze cAMP with a K(m) = 0.5 microM. Incubation of cell supernatant with cAMP dependent protein kinase resulted in a rapid increase in activity within minutes, which resulted from a 2-fold decrease in K(m) with no increase in Vmax. HEL cells grown for 24 h in the presence of 50 microM forskolin, an adenylate cyclase activator, demonstrate further increase in PDE3A of 274% of control (p = 0.03). Cells incubated with forskolin and cycloheximide or actinomycin D demonstrated no increase suggesting that cAMP stimulates PDE3A synthesis by transcriptional regulation. The results indicate that cAMP affects both the short and long-term regulation of PDE3A. The latter effect may play a role in the developing hematopoietic cell and the cardiovascular system to regulate cAMP levels.
authors.affiliation: Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA, USA.
authors.forename: S B
authors.initials: SB
authors.lastname: Sheth
authors.forename: K J
authors.initials: KJ
authors.lastname: Brennan
authors.forename: R
authors.initials: R
authors.lastname: Biradavolu
authors.forename: R W
authors.initials: RW
authors.lastname: Colman
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000302:isolation & purification / Q000378:metabolism*; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D004915:Leukemia, Erythroblastic, Acute / Q000201:enzymology*; D014407:Tumor Cells, Cultured
chemical_list: D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; C517287:PDE3A protein, human