TY - JOUR
T1 - T cell receptor-induced phosphorylation of Sos requires activity of CD45, Lck, and protein kinase C, but not ERK
AU - Zhao, Haoran
AU - Li, Yi Yang
AU - Fucini, Raymond V.
AU - Ross, Susan E.
AU - Pessin, Jeffrey E.
AU - Koretzky, Gary A.
PY - 1997/8/22
Y1 - 1997/8/22
N2 - Stimulation of the T cell antigen receptor (TCR) activates signaling pathways involving protein kinases, phospholipase Cγ1, and Ras. How these second messengers interact to initiate distal activation events is an area of intense scrutiny. In this report, we confirm that TCR ligation results in phosphorylation of Sos, a guanine nucleotide exchange factor for Ras. This requires expression of both the CD45 tyrosine phosphatase and the Lck protein tyrosine kinase and depends upon signaling via protein kinase C. In contrast to previous studies examining requirements for Sos phosphorylation following insulin and epidermal growth factor receptor engagement, we show that TCR- induced phosphorylation of Sos does not require activation of the mitogen- activated protein kinase/extracellular-signal regulated kinase (MEK/ERK) pathway. However, the basal phosphorylation of Sos in T cells is affected by either MEK or MEK-dependent kinases. Although Sos phosphorylation results in its dissociation from Grb2 following insulin stimulation in Chinese hamster ovary cells, TCR engagement on the Jurkat T cell line fails to elicit a similar effect. These data demonstrate that the kinases responsible for Sos phosphorylation differ following ligation of various cell surface receptors and that the consequences of Sos phosphorylation relies, at least in part, on sites of its phosphorylation.
AB - Stimulation of the T cell antigen receptor (TCR) activates signaling pathways involving protein kinases, phospholipase Cγ1, and Ras. How these second messengers interact to initiate distal activation events is an area of intense scrutiny. In this report, we confirm that TCR ligation results in phosphorylation of Sos, a guanine nucleotide exchange factor for Ras. This requires expression of both the CD45 tyrosine phosphatase and the Lck protein tyrosine kinase and depends upon signaling via protein kinase C. In contrast to previous studies examining requirements for Sos phosphorylation following insulin and epidermal growth factor receptor engagement, we show that TCR- induced phosphorylation of Sos does not require activation of the mitogen- activated protein kinase/extracellular-signal regulated kinase (MEK/ERK) pathway. However, the basal phosphorylation of Sos in T cells is affected by either MEK or MEK-dependent kinases. Although Sos phosphorylation results in its dissociation from Grb2 following insulin stimulation in Chinese hamster ovary cells, TCR engagement on the Jurkat T cell line fails to elicit a similar effect. These data demonstrate that the kinases responsible for Sos phosphorylation differ following ligation of various cell surface receptors and that the consequences of Sos phosphorylation relies, at least in part, on sites of its phosphorylation.
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U2 - 10.1074/jbc.272.34.21625
DO - 10.1074/jbc.272.34.21625
M3 - Article
C2 - 9261185
AN - SCOPUS:0030764963
SN - 0021-9258
VL - 272
SP - 21625
EP - 21634
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 34
ER -