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Transduction of Mitogenic Signals in T Lymphocytes
Author(s) -
MUSTELIN T.,
PÖSÖ H.,
STÅHLS A.,
ELORANTA T.,
ANDERSSON LEIF C.
Publication year - 1987
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1111/j.1365-3083.1987.tb02262.x
Subject(s) - inositol , diacylglycerol kinase , inositol phosphate , inositol trisphosphate , ionomycin , second messenger system , ornithine decarboxylase , phosphatidylinositol , concanavalin a , stimulation , biochemistry , phosphorylation , biology , signal transduction , chemistry , sugar phosphates , protein kinase c , enzyme , receptor , endocrinology , in vitro
Treatment of human T lymphocytes with mitogenic ligands, such as concanavalin A (Con A), induces a rapid activation of the enzyme ornithine decarboxylase (ODC). This activation occurs within minutes and is completely inhibited when the cells are treated with 1 mMLi* (in an inostiol‐free medium) prior to stimulation with Con A. In the presence of 1 mM myo‐inositol Li + has no effect on the Con A‐induced activation of ODC. To elucidate why intositol is needed for the mitogen‐induced activation of ODC in T lymphocytes, we tested the ability of different inositol metabolites to reverse the inhibitory effect of Li + . Here we report that inositol phospholipids, in addition to inositol, reverse the Li + ‐induced inhibition of ODC activation, while all other inositol derivatives tested were ineffective, This indicates that Li − does not block the activation of ODC by inhibiting the generation of inositol phosphates, but rather by a mechanism which is circumvented if inositol phospholipids are added. The molecular mechanisms involved in the rapid activation of ODC by mitogens in human T lymphocytes apparently require inositol phospholipids. but are not directly mediated by inasitol‐l,4.5‐trisphosphate (IP 3 ) alone, diacylglycerol alone, or other inositol phosphates.