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.
Seybold
J
J
Thoracic Medicine, Imperial College School of Medicine at the National Heart and Lung Institute, London SW3 6LY, United Kingdom.
Newton
R
R
Wright
L
L
Finney
P A
PA
Suttorp
N
N
Barnes
P J
PJ
Adcock
I M
IM
Giembycz
M A
MA
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