Fibroblast Growth Factor-2 Suppression of Tumor Necrosis Factor α-Mediated Apoptosis Requires Ras and the Activation of Mitogen-activated Protein Kinase

doi:10.1074/jbc.271.24.14560

Fibroblast Growth Factor-2 Suppression of Tumor Necrosis Factor α-Mediated Apoptosis Requires Ras and the Activation of Mitogen-activated Protein Kinase*

From the ^‡ Division of Basic Sciences, National Jewish Center for Immunology and Respiratory Medicine, Denver, Colorado 80206 and the
^¶ Department of Pharmacology, University of Colorado Medical School, Denver, Colorado 80262

^§ To whom correspondence should be addressed:
Division of Basic Sciences, K1007, National Jewish Center for Immunology and Respiratory Medicine, 1400 Jackson St., Denver, CO 80206.
Tel.: 303-398-1772; Fax: 303-398-1225.

Abstract

Treatment of L929 cells with tumor necrosis factor α (TNFα) activates a programmed cell death pathway resulting in apoptosis. We investigated the intracellular signaling pathways activated in L929 cells by TNFα. TNFα robustly activates Jun kinase (JNK), a member of the mitogen-activated protein kinase (MAPK) family. In addition, p42^MAPK is activated, but a 10-fold greater concentration of TNFα was required for substantial MAPK activation than was needed for maximal JNK stimulation. Simultaneous treatment of L929 cells with fibroblast growth factor (FGF-2) significantly reduced the apoptotic response to TNFα. FGF-2 substantially activated the Raf/MEK/MAPK (where MEK is mitogen-activated protein kinase kinase) pathway but did not affect TNFα activation of JNK. These results indicate that although JNK may play an important role in transmitting the TNFα signal from the cell surface to the nucleus, activation of the JNK pathway is not sufficient to induce apoptosis. Expression of dominant-negative Asn-17 Ras in L929 cells diminished the FGF-2 stimulation of p42^MAPK and eliminated the protective effect of FGF-2. Asn-17 Ras expression did not affect JNK activity and had no effect on TNFα activation of JNK. Pharmacological inhibition of MEK-1 activity by incubation of cells with the compound PD 098059 blocked p42^MAPK activation and FGF-2 protection against apoptosis. Interestingly, activated Val-12 Ras expression substantially enhanced TNFα-mediated apoptosis in L929 cells, but Val-12 Ras did not constitutively activate MAPK in L929 cells and FGF-2 partially protected Val-12 Ras-expressing cells from TNFα-mediated apoptosis. Our data indicate that activation of the MAPK pathway mediates an FGF-2 protective effect against apoptosis and highlights the important role that integration of multiple intracellular signaling pathways plays in the regulation of cell growth and death.

Footnotes

↵* This work was supported by National Institutes of Health Grants DK37871, GM30324, DK48845, and CA58157 (to G. L. J.) and CA60455 (to A. M. G.). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

TNFα

tumor necrosis factor α

p55^TNFR

55-kDa tumor necrosis factor receptor

p75^TNFR

75-kDa tumor necrosis factor receptor

MAPK

mitogen-activated protein kinase

JNK

Jun kinase

FGF-2

fibroblast growth factor-2

MEK

mitogen-activated protein kinase kinase

PBS

phosphate-buffered saline

CAPS

3-(cyclohexylamino)propanesulfonic acid

GST-Jun

glutathione S-transferase-c-Jun_(1–79)

EGFR_662-681

epidermal growth factor receptor 662–681 peptide

PAGE

polyacrylamide gel electrophoresis

PIPES

1,4-piperazinediethanesulfonic acid

IPTG

isopropyl-1-thio-β-D-galactopyranoside

PD

MEK-1 inhibitor PD 098059.
- Received February 1, 1996.
- Revision received April 2, 1996.