Intact and functional fibroblast growth factor (FGF) receptor-1 trafficks near the nucleus in response to FGF-1

• Published in: The Journal of biological chemistry Vol. 269; no. 50; pp. 31720 - 31724
• Main Authors: Prudovsky, I, Savion, N, Zhan, X, Friesel, R, Xu, J, Hou, J, McKeehan, W L, Maciag, T
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 16.12.1994; American Society for Biochemistry and Molecular Biology
• Subjects: 3T3 Cells; Animals; Cell Compartmentation; Cell Cycle; Cell Nucleus - metabolism; Fibroblast Growth Factor 1 - metabolism; Fluorescent Antibody Technique; Mice; Molecular Weight; Receptor Protein-Tyrosine Kinases - metabolism; Receptor, Fibroblast Growth Factor, Type 1; Receptors, Fibroblast Growth Factor - metabolism; Recombinant Proteins
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)31755-1

Exogenous fibroblast growth factor-1 (FGF-1) associates with the nucleus in a receptor-dependent manner during the entire G1 period of the BALB/c 3T3 cell cycle (Zhan, X., Hu, X., Friesel, R., and Maciag, T. (1993) J. Biol. Chem. 268, 9611-9620). To further study the role of the FGF receptor (FGFR) during this translocation, the intracellular fate of FGFR-1 protein and enzymatic activity was examined. Immunoprecipitation using multiple FGFR-1 antibodies followed by an in vitro tyrosine kinase activity assay enabled us to identify FGFR-1 as a 130-kDa phosphotyrosine-containing protein associated with the nuclear fraction of NIH 3T3 cells exposed to FGF-1. While FGFR-1 tyrosine kinase activity could be detected as a nuclear-associated protein after a 2-h exposure of the NIH 3T3 cells to FGF-1, this activity appeared to be maximal in the nuclear fraction between 4 and 12 h after FGF-1 treatment. In addition, analysis by confocal immunofluorescence microscopy of quiescent and FGF-1-stimulated NIH 3T3 cells reveal a prominent perinuclear FGFR-1 staining pattern in the cells exposed to FGF-1 but not in the quiescent population. We also observed FGFR-1 associated with the nuclear fraction in FGFR-1-transfected L6 rat myoblasts, which are known to be refractive to exogenous FGF-1 and express relatively low levels of endogenous FGFR-1. In addition, these cells also exhibited the presence of a 145-kDa phosphoprotein in the nuclear fraction that was recognized by FGFR-1 antibodies. These results suggest that the FGFR-1 may be translocated near the nucleus upon interaction with its ligand during the entire G1 period of the NIH 3T3 cell cycle as a structurally intact and functional tyrosine kinase that may be accessible to perinuclear polypeptides as a regulatory enzyme.