Phenylarsine oxide and phorbol myristate acetate inhibit the CD3-induced rise of cytosolic Ca2+ in Jurkat cells by refilling internal Ca2+ stores.
Phenylarsine oxide (PAO), an inhibitor of tyrosine phosphatases, has been found to inhibit the early elevation in cytosolic Ca2+ concentration ([Ca2+]i), related to the CD3 activation pathway in Jurkat T cells. This inhibition was dose-dependent, consistent with previously reported effects of PAO on tyrosine phosphatases, and reversed by dimercaptopropanol. By contrast, okadaic acid, an inhibitor of serine/threonine phosphatases, had no effect on CD3-induced Ca2+ flux. PAO was compared with phorbol 12-myristate 13-acetate (PMA), which caused a similar, although less potent, inhibition as previously described. The two reagents produced additive inhibition of the CD3-induced [Ca2+]i rise, but did not affect thapsigargin- or ionomycin-driven Ca2+ flux in Jurkat cells. PAO and PMA prevented cells from complete depletion of intracellular Ca2+ stores by an anti-CD3 monoclonal antibody (mAb) and restored, at least partially, the ionomycin-sensitive pool, when added after anti-CD3 mAb. Moreover, the CD3-induced inhibition of phosphatidylserine synthesis, due to depletion of internal Ca2+ stores, is reversed by PAO and PMA. Anti-phosphotyrosine immunoblot analysis show that these effects cannot be accounted for by an inhibition of CD3-induced tyrosine phosphorylations. We propose that PAO and, to a lesser extent, PMA allow the refilling of internal compartments by Ca2+, which consequently abrogates a capacitative entry of external Ca2+.
Deckert
M
M
INSERM U343, Faculté de Médecine, Nice, France.
Aussel
C
C
Bernard
A
A
Breittmayer
J P
JP
D001152:Arsenicals / Q000494:pharmacology*; D001692:Biological Transport; D017252:CD3 Complex / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism; D004988:Ethers, Cyclic / Q000494:pharmacology; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D019319:Okadaic Acid; D010718:Phosphatidylserines / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D010766:Phosphorylation; D013601:T-Lymphocytes / Q000187:drug effects* / Q000378:metabolism; D013729:Terpenes / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D019284:Thapsigargin; D014443:Tyrosine / Q000378:metabolism
D001152:Arsenicals; D017252:CD3 Complex; D004988:Ethers, Cyclic; D010718:Phosphatidylserines; D013729:Terpenes; C029341:oxophenylarsine; D019319:Okadaic Acid; D014443:Tyrosine; D015759:Ionomycin; D019284:Thapsigargin; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium