Induction of phosphodiesterases 3B, 4A4, 4D1, 4D2, and 4D3 in Jurkat T-cells and in human peripheral blood T-lymphocytes by 8-bromo-cAMP and Gs-coupled receptor agonists. Potential role in beta2-adrenoreceptor desensitization.
In this study, a potential mechanism of beta2-adrenoreceptor desensitization has been explored that is based upon the enhanced degradation of cAMP by phosphodiesterase (PDE). Pretreatment of Jurkat T-cells with 8-bromo cAMP (8-Br-cAMP) or prostaglandin E2 increased PDE3 and PDE4 activity in an actinomycin D- and cycloheximide-sensitive manner. This effect was associated with increased expression of HSPDE3B, HSPDE4A4, HSPDE4D1, HSPDE4D2, and HSPDE4D3 mRNA transcripts. Western analysis reproducibly labeled a band of immunoreactivity in vehicle-treated cells that corresponded to HSPDE4A4 (125 kDa). Although the intensity of this band was unchanged in cells treated with 8-Br-cAMP, additional 68-72-kDa proteins (HSPDE4D2, HSPDE4D1) were labeled that were not detected after vehicle. Similar results were obtained with T-lymphocytes exposed to 8-Br-cAMP and fenoterol. However, in those experiments HSPDE4A4 and HSPDE4D1 appeared to be equally expressed in vehicle- and treated cells, whereas HSPDE4D2 (72 kDa) was detected only after 8-Br-cAMP. The up-regulation of PDE activity in Jurkat T-cells abolished the ability of isoproterenol to elevate cAMP, which was partially reversed by the non-selective PDE inhibitor, 3-isobutyl-1-methylxanthine, and by the PDE3 and PDE4 inhibitors, Org 9935 and rolipram, respectively. Collectively, these data suggest that chronic treatment of T-cells with cAMP-elevating agents compromises beta2-adrenoreceptor-mediated cAMP accumulation by increasing the expression of HSPDE3B and HSPDE4D gene products.
Thoracic Medicine, Imperial College School of Medicine at the National Heart and Lung Institute, London SW3 6LY, United Kingdom.
J
J
Seybold
R
R
Newton
L
L
Wright
P A
PA
Finney
N
N
Suttorp
P J
PJ
Barnes
I M
IM
Adcock
M A
MA
Giembycz
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D001249:Asthma / Q000503:physiopathology; D000242:Cyclic AMP / Q000494:pharmacology; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D015232:Dinoprostone / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005280:Fenoterol / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D019169:Jurkat Cells; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D013601:T-Lymphocytes / Q000201:enzymology*; D015854:Up-Regulation / Q000187:drug effects
D000318:Adrenergic beta-Agonists; D004791:Enzyme Inhibitors; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D011943:Receptors, Adrenergic, beta; D005280:Fenoterol; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000242:Cyclic AMP; D010727:Phosphoric Diester Hydrolases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D019204:GTP-Binding Proteins; D015232:Dinoprostone; D007545:Isoproterenol