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Mol Cell Biol, July 1998, p. 3762-3770, Vol. 18, No. 7
Graduate Program in Molecular Biology and
Biochemistry,1
Department of Molecular
Genetics and Microbiology,3 and
Department of Neurobiology and
Behavior,4 Institute of Cell and Developmental
Biology, State University of New York at Stony Brook, Stony Brook,
New York 11794, and
Department of Molecular Biology and
Pharmacology, Washington University Medical School, St. Louis,
Missouri 63110-81032
Received 11 November 1997/Returned for modification 24 December
1997/Accepted 14 April 1998
Fibroblast growth factor 1 (FGF-1) induces neurite outgrowth in
PC12 cells. Recently, we have shown that the FGF receptor 1 (FGFR-1) is
much more potent than FGFR-3 in induction of neurite outgrowth. To
identify the cytoplasmic regions of FGFR-1 that are responsible for the
induction of neurite outgrowth in PC12 cells, we took advantage of this
difference and prepared receptor chimeras containing different regions
of the FGFR-1 introduced into the FGFR-3 protein. The chimeric
receptors were introduced into FGF-nonresponsive variant PC12 cells
(fnr-PC12 cells), and their ability to mediate FGF-stimulated neurite
outgrowth of the cells was assessed. The juxtamembrane (JM) and
carboxy-terminal (COOH) regions of FGFR-1 were identified as conferring
robust and moderate abilities, respectively, for induction of neurite outgrowth to FGFR-3. Analysis of FGF-stimulated activation of signal
transduction revealed that the JM region of FGFR-1 conferred strong and
sustained tyrosine phosphorylation of several cellular proteins and
activation of MAP kinase. The SNT/FRS2 protein was demonstrated to be
one of the cellular substrates preferentially phosphorylated by
chimeras containing the JM domain of FGFR-1. SNT/FRS2 links FGF
signaling to the MAP kinase pathway. Thus, the ability of FGFR-1 JM
domain chimeras to induce strong sustained phosphorylation of this
protein would explain the ability of these chimeras to activate MAP
kinase and hence neurite outgrowth. The role of the COOH region of
FGFR-1 in induction of neurite outgrowth involved the tyrosine residue
at amino acid position 764, a site required for phospholipase C gamma
binding and activation, whereas the JM region functioned primarily
through a non-phosphotyrosine-dependent mechanism. In contrast,
assessment of the chimeras in the pre-B lymphoid cell line BaF3 for
FGF-1-induced mitogenesis revealed that the JM region did not play a
role in this cell type. These data indicate that FGFR signaling can be
regulated at the level of intracellular interactions and that signaling
pathways for neurite outgrowth and mitogenesis use different regions of
the FGFR.
0270-7306/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Identification of the Cytoplasmic Regions of
Fibroblast Growth Factor (FGF) Receptor 1 Which Play Important Roles in
Induction of Neurite Outgrowth in PC12 Cells by FGF-1

*
Corresponding author. Mailing address: Department of
Molecular Genetics and Microbiology, Institute of Cell and
Developmental Biology, State University of New York at Stony Brook,
Stony Brook, NY 11794. Phone: (516) 632-8792. Fax: (516) 632-8891. E-mail: hayman{at}asterix.bio.sunysb.edu.
Present address: Department of Molecular Biology, Princeton
University, Princeton, NJ 08544-1014.
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