Role of the phospholipase C-inositol 1,4,5-trisphosphate pathway in calcium release-activated calcium current and capacitative calcium entry

Citation
Lm. Broad et al., Role of the phospholipase C-inositol 1,4,5-trisphosphate pathway in calcium release-activated calcium current and capacitative calcium entry, J BIOL CHEM, 276(19), 2001, pp. 15945-15952
Citations number
44
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biochemistry & Biophysics
Journal title
JOURNAL OF BIOLOGICAL CHEMISTRY
ISSN journal
0021-9258 → ACNP
Volume
276
Issue
19
Year of publication
2001
Pages
15945 - 15952
Database
ISI
SICI code
0021-9258(20010511)276:19<15945:ROTPC1>2.0.ZU;2-C
Abstract
We investigated the putative roles of phospholipase C, polyphosphoinositide s, and inositol 1,4,5-trisphosphate (IP3) in capacitative calcium entry and calcium release-activated calcium current (I-crac) in lacrimal acinar cell s, rat basophilic leukemia cells, and DT40 B-lymphocytes, Inhibition of pho spholipase C with U73122 blocked calcium entry and I-crac activation whethe r in response to a phospholipase C-coupled agonist or to calcium store depl etion with thapsigargin. Run-down of cellular polyphosphoinositides by conc entrations of wortmannin that block phosphatidylinositol 4-kinase completel y blocked calcium entry and I-crac. The membrane-permeant IP3 receptor inhi bitor, 2-aminoethoxydiphenyl borane, blocked both capacitative calcium entr y and I-crac. However, it is likely that 2-aminoethoxydipheny1 borane does not inhibit through an action on the IP3 receptor because the drug was equa lly effective in wild-type DT40 B-cells and in DT40 B-cells whose genes for all three IP3 receptors had been disrupted. Intracellular application of a nother potent IP3 receptor antagonist, heparin, failed to inhibit activatio n of I-crac. Finally, the inhibition of I-crac activation by U73122 or wort mannin was not reversed or prevented by direct intracellular application of IP3. These findings indicate a requirement for phospholipase C and for pol yphosphoinositides for activation of capacitative calcium entry. However, t he results call into question the previously suggested roles of IP3 and IP3 receptor in this mechanism, at least in these particular cell types.