Effects of pertussis toxin on signal transductions via P2-purinergic receptors in A-431 human epidermoidal carcinoma cells.
In A-431 cells, stimulation of P2-purinergic receptors with extracellular ATP caused production of inositol 1,4,5-trisphosphate (InsP3), followed by mobilization of Ca2+ from intracellular stores; Ca2+ influx from the extracellular fluid and breakdown of phosphatidylcholine (PtdCho) also accompanied this InsP3/Ca2+ signalling. When A-431 cells were pretreated with pertussis toxin (PTX), production of InsP3 and elevation of cytosolic Ca2+ were strongly inhibited. PTX also inhibited the Ca2+ influx, but the effect was much weaker than that for InsP3/Ca2+ elevation. No inhibitory effect was observed in ATP-stimulated PtdCho breakdown. These results suggest that there is a system(s) which mediates the functions of P2-purinergic receptors in addition to PTX-sensitive G-proteins.
Sugita
K
K
Department of Oral Physiology, Meikai University School of Dentistry, Saitama, Japan.
Kurihara
K
K
Hosoi
K
K
Atsumi
T
T
Takahashi
T
T
Kohno
M
M
Ueha
T
T
D000255:Adenosine Triphosphate / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000378:metabolism; D002794:Choline / Q000378:metabolism; D005453:Fluorescence; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D037342:Pertussis Toxin; D010713:Phosphatidylcholines / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D010713:Phosphatidylcholines; D018048:Receptors, Purinergic P2; D010566:Virulence Factors, Bordetella; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D002794:Choline; D002118:Calcium