Role of the phospholipase C-inositol 1,4,5-trisphosphate pathway in calcium release-activated calcium current and capacitative calcium entry.
We investigated the putative roles of phospholipase C, polyphosphoinositides, and inositol 1,4,5-trisphosphate (IP(3)) in capacitative calcium entry and calcium release-activated calcium current (I(crac)) in lacrimal acinar cells, rat basophilic leukemia cells, and DT40 B-lymphocytes. Inhibition of phospholipase C with blocked calcium entry and I(crac) activation whether in response to a phospholipase C-coupled agonist or to calcium store depletion with thapsigargin. Run-down of cellular polyphosphoinositides by concentrations of wortmannin that block phosphatidylinositol 4-kinase completely blocked calcium entry and I(crac). The membrane-permeant IP(3) receptor inhibitor, 2-aminoethoxydiphenyl borane, blocked both capacitative calcium entry and I(crac). However, it is likely that 2-aminoethoxydiphenyl borane does not inhibit through an action on the IP(3) receptor because the drug was equally effective in wild-type DT40 B-cells and in DT40 B-cells whose genes for all three IP(3) receptors had been disrupted. Intracellular application of another potent IP(3) receptor antagonist, heparin, failed to inhibit activation of I(crac). Finally, the inhibition of I(crac) activation by or wortmannin was not reversed or prevented by direct intracellular application of IP(3). These findings indicate a requirement for phospholipase C and for polyphosphoinositides for activation of capacitative calcium entry. However, the results call into question the previously suggested roles of IP(3) and IP(3) receptor in this mechanism, at least in these particular cell types.
Laboratory of Signal Transduction, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
L M
LM
Broad
F J
FJ
Braun
J P
JP
Lievremont
G S
GS
Bird
T
T
Kurosaki
J W
JW
Putney
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001402:B-Lymphocytes; D001896:Boron Compounds / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D015220:Calcium Channels / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D002645:Chickens; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D006493:Heparin / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007700:Kinetics; D007765:Lacrimal Apparatus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015471:Leukemia, Basophilic, Acute; D051379:Mice; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D019284:Thapsigargin / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism*; D000077191:Wortmannin
D000730:Androstadienes; D001896:Boron Compounds; D015220:Calcium Channels; D004791:Enzyme Inhibitors; D004963:Estrenes; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018129:Phosphatidylinositol Phosphates; D011760:Pyrrolidinones; D018160:Receptors, Cytoplasmic and Nuclear; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D019284:Thapsigargin; D015544:Inositol 1,4,5-Trisphosphate; D006493:Heparin; C109986:2-aminoethoxydiphenyl borate; D010738:Type C Phospholipases; D002118:Calcium; D000077191:Wortmannin