Inositol 1,4,5-trisphosphate generation and calcium mobilisation via activation of an atypical P2 receptor in the neuronal cell line, N1E-115.
1. Alterations in the levels of intracellular calcium ([Ca2+]i) and D-myo-inositol-1,4,5-trisphosphate (InsP3) were measured in the murine neuroblastoma cell line clone, N1E-115, by use of the calcium-sensitive dye, fura-2 and a radioreceptor assay, respectively. 2. Exposure of the cells to ATP (100 microM) elicited rapid and transient increases in [Ca2+]i and InsP3, with both responses reaching a maximum between 10-20 s after agonist addition. 3. Investigation of concentration-response data by use of various analogues of ATP suggests the presence of an extracellular receptor which fails to fit into the current classification of purinoceptors. 4. Cross-desensitization experiments suggest that the same receptor can also be activated by the structurally different pyrimidine base, UTP. 5. Application of the tumour-promoting agent, beta-phorbol-12,13 dibutyrate (PDBu) caused a reduction in the increases in both [Ca2+]i and InsP3, suggesting a role for protein kinase C in feedback inhibition of purinoceptor responses in this cell line. 6. In summary, we present the first evidence for the existence of an atypical purinoceptor on a cell line of CNS origin. This receptor is linked to stimulation of phosphoinositide turnover and subsequent mobilisation of intracellular calcium.
Iredale
P A
PA
Department of Physiology and Pharmacology, Medical School, Queen's Medical Centre, Nottingham.
Martin
K F
KF
Alexander
S P
SP
Hill
S J
SJ
Kendall
D A
DA
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D016257:Fura-2 / Q000378:metabolism; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D051379:Mice; D009447:Neuroblastoma; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011869:Radioligand Assay; D011983:Receptors, Purinergic / Q000187:drug effects / Q000502:physiology*; D014407:Tumor Cells, Cultured; D014544:Uridine Triphosphate / Q000494:pharmacology
D011983:Receptors, Purinergic; D015240:Phorbol 12,13-Dibutyrate; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D002118:Calcium; D016257:Fura-2; D014544:Uridine Triphosphate