Inhibition of MAP Kinase Kinase Blocks the Differentiation of PC-12 Cells Induced by Nerve Growth Factor(*)
- From the (1) Department of Signal Transduction, Parke-Davis Pharmaceutical Research, Warner-Lambert Co., Ann Arbor, Michigan 48105 and Department of
- (2) Physiology and
- (3) Microbiology, University of Michigan School of Medicine, Ann Arbor, Michigan 48109
- ¶ To whom correspondence should be addressed: Dept. of Signal Transduction, Parke-Davis Pharmaceutical Research/Warner-Lambert Co., 2800 Plymouth Rd., Ann Arbor, MI 48105. Tel.: 313-996-3960; Fax: 313-996-5668.
Abstract
The mitogen-activated protein kinase (MAP kinase) pathway is thought to play an important role in the actions of neurotrophins.
A small molecule inhibitor of the upstream kinase activator of MAP kinase, MAP kinase kinase (MEK) was examined for its effect
on the cellular action of nerve growth factor (NGF) in PC-12 pheochromocytoma cells. PD98059 selectively blocks the activity
of MEK, inhibiting both the phosphorylation and activation of MAP kinases in vitro. Pretreatment of PC-12 cells with the compound completely blocked the 4-fold increase in MAP kinase activity produced by
NGF. Half-maximal inhibition was observed at 2 μM PD98059, with maximal effects at 10-100 μM. The tyrosine phosphorylation
of immunoprecipitated MAP kinase was also completely blocked by the compound. In contrast, the compound was without effect
on NGF-dependent tyrosine phosphorylation of the pp140
receptor or its substrate Shc and did not block NGF-dependent activation of phosphatidylinositol 3′-kinase. However, PD98059completely
blocked NGF-induced neurite formation in these cells without altering cell viability. These data indicate that the MAP kinase
pathway is absolutely required for NGF-induced neuronal differentiation in PC-12 cells.
Footnotes
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↵* 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:
- NGF
-
nerve growth factor
- MAP kinase
-
mitogen-activated protein kinase
- MEK
-
MAP kinase kinase
- PAGE
-
polyacrylamide gel electrophoresis
- PI
-
phosphatidylinositol
- MAP-2
-
microtubule-associated protein-2.
-
↵2Dudley, D. T., Pang, L., Decker, S. J., Bridges, A. J., and Saltiel, A. R. (1995) Proc. Natl. Acad. Sci. U. S. A., in press.
- © 1995 by The American Society for Biochemistry and Molecular Biology, Inc.
