U937 monocytic cells are shown here to express a range of PDE4, cAMP-specific phosphodiesterase (PDE) isoenzymes: the long isoenzymes, PDE4A4, PDE4D5 and PDE4D3, plus the short isoenzyme, PDE4B2. These isoenzymes provide around 76% of the total cAMP PDE activity of U937 cells. The specific activities of the total PDE4A, PDE4B and PDE4D activities were 0.63±0.09, 8.8±0.2 and 34.4±2.9 pmol/min per mg of protein respectively. The PDE4 selective inhibitor, rolipram, inhibited immunopurified PDE4B and PDE4D activities similarly, with IC50 values of approx. 130 nM and 240 nM respectively. In contrast, rolipram inhibited immunopurified PDE4A activity with a dramatically lower IC50 value of around 3 nM. Rolipram increased phosphorylation of cAMP-response-element-binding protein (CREB) in U937 cells in a dose-dependent fashion, which implied the presence of both high affinity (IC50 value approx. 1 nM) and low affinity (IC50 value approx. 120 nM) components. Rolipram dose-dependently inhibited the interferon-γ (IFN-γ)-stimulated phosphorylation of p38 mitogen-activated protein (MAP) kinase in a simple monotonic fashion with an IC50 value of approx. 290 nM. On this basis, it is suggested that rolipram inhibition of PDE4A4 is involved in regulating CREB phosphorylation but not IFN-γ-stimulated p38 MAP kinase phosphorylation. PDE4A4 was also selectively activated by challenge of U937 cells with either bacterial lipopolysaccharide (LPS) or IFN-γ through a process which was attenuated by both wortmannin and rapamycin. It is proposed that the PDE4A4 isoform is involved in compartmentalized cAMP signalling responses in U937 monocytes.
Skip Nav Destination
Close
Article navigation
April 2000
- Cover Image
- PDF Icon PDF LinkFront Matter
- PDF Icon PDF LinkTable of Contents
Research Article|
April 10 2000
Action of rolipram on specific PDE4 cAMP phosphodiesterase isoforms and on the phosphorylation of cAMP-response-element-binding protein (CREB) and p38 mitogen-activated protein (MAP) kinase in U937 monocytic cells
Simon J. MACKENZIE;
Simon J. MACKENZIE
1Molecular Pharmacology Group, Division of Biochemistry and Molecular Biology, Davidson and Wolfson Buildings, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K.
Search for other works by this author on:
Miles D. HOUSLAY
Miles D. HOUSLAY
1
1To whom correspondence should be addressed (e-mail M.Houslay@;bio.gla.ac.uk).
Search for other works by this author on:
Biochem J (2000) 347 (2): 571–578.
Article history
Received:
November 24 1999
Revision Received:
January 20 2000
Accepted:
February 17 2000
Citation
Simon J. MACKENZIE, Miles D. HOUSLAY; Action of rolipram on specific PDE4 cAMP phosphodiesterase isoforms and on the phosphorylation of cAMP-response-element-binding protein (CREB) and p38 mitogen-activated protein (MAP) kinase in U937 monocytic cells. Biochem J 15 April 2000; 347 (2): 571–578. doi: https://doi.org/10.1042/bj3470571
Download citation file:
Close
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Biochemical Society Member Sign in
Sign InSign in via your Institution
Sign in via your InstitutionGet Access To This Article
9
Views
0
Citations
Cited By
Related Articles
Interferon-γ regulates nucleoside transport systems in macrophages through signal transduction and activator of transduction factor 1 (STAT1)-dependent and -independent signalling pathways
Biochem J (November,2003)
Subcellular localization of proteasomes and their regulatory complexes in mammalian cells
Biochem J (February,2000)