Leukotriene D4 induces a rapid increase in cAMP in the human epithelial cell line, Int 407: a potential role for this signal in the regulation of calcium influx through the plasma membrane

Cell Calcium. 1998 Jul;24(1):9-16. doi: 10.1016/s0143-4160(98)90084-7.


Although the LTD4-induced Ca2+ influx in human epithelial cells has been shown to be regulated by a pertussis toxin-sensitive heterotrimeric G-protein, most likely a G alpha i3 protein [Adolfsson J.L.P., Ohd J.F., Sjölander A. Leukotriene D4-induced activation and translocation of the G-protein alpha i3-subunit in human epithelial cells. Biochem Biophys Res Commun 1996; 226: 413-419], the signalling pathway further downstream is still unclear. In the present study, we investigated the possible involvement of cAMP and protein kinase A activity in the LTD4-induced Ca2+ influx in the epithelial cell line Int 407. Stimulation with LTD4, but not with the calcium ionophore ionomycin, triggered a rapid increase (peak at 7 s) in the cellular cAMP level, an effect that was totally abolished by pertussis toxin. Furthermore, the LTD4-induced Ca2+ signal was reduced by 60% when cells that had been pre-incubated with the protein kinase A inhibitor Rp-cAMPS (50 microM for 30 min) were stimulated in a calcium containing medium. In contrast, Rp-cAMPS had no apparent effect on the LTD4-induced Ca2+ signal when the cells were stimulated in a calcium-depleted medium. The immediate LTD4-induced protein tyrosine phosphorylation (15 s), previously shown to be necessary for the subsequent Ca2+ influx, was abolished not only by pretreatment with pertussis toxin but also by exposure to Rp-cAMPS. Furthermore, direct activation of the cellular adenylyl cyclase activity by treatment with forskolin alone induced a prompt Ca2+ signal in the presence, but not in the absence, of extracellular Ca2+, identical results were obtained with the cell permeable cAMP analogue 8-bromo-cAMP. In addition, forskolin induced protein tyrosine phosphorylation similar to that seen with LTD4. These results suggest that protein kinase A activity participates in the regulation of the LTD4-induced Ca2+ influx at a site that is downstream of the activation of the pertussis toxin-sensitive G-protein but upstream of a LTD4-stimulated tyrosine kinase(s).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenylyl Cyclases / metabolism
  • Calcium / metabolism*
  • Calcium Signaling
  • Cell Line
  • Cell Membrane / metabolism*
  • Colforsin / pharmacology
  • Cyclic AMP / analogs & derivatives
  • Cyclic AMP / metabolism*
  • Cyclic AMP / pharmacology
  • Cyclic AMP-Dependent Protein Kinases / antagonists & inhibitors
  • Enzyme Inhibitors / pharmacology
  • Epithelial Cells
  • GTP-Binding Proteins / metabolism
  • Humans
  • Isoenzymes / metabolism
  • Leukotriene D4 / physiology*
  • Phosphorylation
  • Thionucleotides / pharmacology
  • Tyrosine / metabolism


  • Enzyme Inhibitors
  • Isoenzymes
  • Thionucleotides
  • Colforsin
  • adenosine-3',5'-cyclic phosphorothioate
  • Tyrosine
  • Leukotriene D4
  • Cyclic AMP
  • Cyclic AMP-Dependent Protein Kinases
  • GTP-Binding Proteins
  • Adenylyl Cyclases
  • Calcium