T-Cell Receptor Signaling Pathway Exerts a Negative Control on
Thrombin-Mediated Increase in [Ca2+]i and
p38 MAPK Activation in Jurkat T Cells: Implication of the Tyrosine
Kinase p56Lck
Laurence Maulon,
Sandrine Guérin,
Jean-Ehrland Ricci,
Dariush FarahiFar, Jean-Philippe Breittmayer, and
Patrick Auberger
From CJF INSERM 96.05, Activation des Cellules
Hématopoiétiques, Faculté de Médecine, Nice
Cédex, France; INSERM U343, Hôpital de l'Archet, Nice,
France; and INSERM U364, Faculté de Médecine, Nice
Cédex, France.
Activation of the mitogen-activated protein kinase (Erk) and c-Jun
terminal kinase is a well-documented mechanism for the seven
transmembrane spanning receptors. We have previously shown that
thrombin stimulation of the T-leukemic cell line Jurkat induced a
transient increase in [Ca2+]i and tyrosine
phosphorylation of several cellular proteins. Here, we
have analyzed p42-44 MAPK, JNK and p38 MAPK activation using Jurkat
T-cell lines deficient in either the tyrosine kinase p56Lck (JCaM1) or
the tyrosine phosphatase CD45 (J45.01). Our results demonstrate that
p56Lck and CD45 exert a negative control on thrombin-induced p38 MAPK
activation and [Ca2+]i release in Jurkat
cells. Thrombin receptor expression was identical on the different cell
lines as assessed by FACS analysis. Tyrosine phosphorylation of p38
MAPK was drastically increased after thrombin stimulation of JCaM1 or
J45.01 cells, as compared with parental cells (JE6.1). P42-44 MAPK and
JNK activity also enhanced after thrombin treatment of JE6.1 and JCaM1
cell lines, whereas basal kinase activity was higher in J45.01 cells
and was not further stimulated by thrombin. Thrombin and thrombin
receptor agonist peptide-induced [Ca2+]i
mobilization paralleled p38 MAPK activation in JCaM1 and J45.01 cells.
Moreover, reconstitution of J45.01 and JCaM1 cell lines with either
CD45 or Lck is accompanied by restoration of a normal thrombin-induced
[Ca2+]i response and p38MAPK
phosphorylation. These data show that a component of the T-cell
receptor signaling pathway exerts a negative control on
thrombin-induced responses in Jurkat T cells. Accordingly, we found
that thrombin enhanced tyrosine phosphorylation of p56Lck and decreased
p56Lck kinase activity in J45.01 cells. Our results are consistent with
a negative role for p56Lck on thrombin-induced
[Ca2+]i release and p38 MAPK activation in
Jurkat T-cell lines.
Blood, Vol. 91 No. 11 (June 1), 1998:
pp. 4232-4241
© 1998 by The American Society of Hematology.
