v-Abl-mediated Apoptotic Suppression Is Associated with SHC Phosphorylation without Concomitant Mitogen-activated Protein Kinase Activation (*)
- From the Leukaemia Research Fund Group, Department of Biochemistry and Applied Molecular Biology, University of Manchester, Institute of Science and Technology, Sackville Street, Manchester M60 1QD, United Kingdom
- § To whom correspondence should be addressed.
Abstract
A temperature-sensitive mutant of the v-Abl protein has previously been shown to exhibit tyrosine protein kinase activity
in Interleukin 3 (IL-3)-dependent IC.DP cells grown at the permissive temperature (32°C) but not at the restrictive temperature
(39°C). These IC.DP cells are dependent on IL-3 for suppression of apoptosis at 39°C, but at 32°C cells will survive without
added growth factor. Both IL-3 and v-Abl stimulated the tyrosine phosphorylation of SHC and GTPase-activating protein. However,
while IL-3 stimulated similar levels of tyrosine phosphorylation in p46
and p52
, v-Abl preferentially phosphorylated p52
, an event that occurred within 1 h of temperature switch. v-Abl also differentially associated with p46
in a temperatureindependent manner. In contrast, only IL-3 stimulated detectable increases in both myelin basic protein kinase
and mitogen-activated protein (MAP) kinase kinase in in vitro assays, although in more specific MAP kinase activity assays a very slight increase in the activity of this enzyme was observed
after 6 h at the permissive temperature. Time course studies suggest that phosphorylation and association of SHC with v-Abl
is insufficient to lead to significant activation of MAP kinase and that activation of the MAP kinase kinase/MAP kinase pathway
is not required for apoptotic suppression.
Footnotes
-
↵* This work was supported by the Leukaemia Research Fund. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
-
↵1 The abbreviations used are:
- PTK
-
protein tyrosine kinase
- IL
-
interleukin
- ERK
-
extracellulary regulated kinase
- GAP
-
GTPase-activating protein
- PAGE
-
polyacrylamide gel electrophoresis
- MBP
-
myelin basic protein.
-
- Received December 15, 1994.
- © 1995 by The American Society for Biochemistry and Molecular Biology, Inc.
