Fibroblast growth factor 3, a protein with dual subcellular localization, is targeted to the nucleus and nucleolus by the concerted action of two nuclear localization signals and a nucleolar retention signal.
The major isoform of fibroblast growth factor 3 (FGF3) is initiated from a CUG codon, and the resultant product is distributed to the nucleus/nucleolus and secretory pathway. This dual subcellular localization is achieved in part by the competing effects of two classical intracellular targeting signals located near the amino terminus. At the extreme amino terminus is a short stretch of 29 amino acids before a signal peptide necessary for translocation into the endoplasmic reticulum, which is next to an adjacent bipartite nuclear localization signal. The carboxyl-terminal region of FGF3 is also implicated in nuclear/nucleolar localization. We describe here the characterization of carboxyl-terminal signals by showing they are capable of directing a heterologous protein, beta-galactosidase, to the nucleus. Furthermore, appending both the amino- and carboxyl-terminal domains onto beta-galactosidase, reproduces the dual subcellular localization properties of FGF3. Nuclear uptake of FGF3 appears to be signal-mediated since it binds to karyopherin alpha, the nuclear localization signal binding subunit of a heterodimeric receptor of the nuclear import machinery. The import of FGF3 into the nucleus is energy-dependent, and the inhibition of this process has demonstrated the importance of the nucleolar retention signal in nucleoplasmic and nucleolar accumulation.
Antoine
M
M
Ruhr-Universitaet Bochum, Medizinische Fakultaet, Institut fuer Hygiene und Mikrobiologie, Abteilung fuer Medizinische Mikrobiologie Virologie, Universitaetsstrasse 150, D-44780, Bochum, Gebaeude MA 6/130, Germany.
Reimers
K
K
Dickson
C
C
Kiefer
P
P
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002466:Cell Nucleolus / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D051518:Fibroblast Growth Factor 3; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D011770:Pyruvate Kinase / Q000378:metabolism; D015398:Signal Transduction; D001616:beta-Galactosidase / Q000378:metabolism
C496444:FGF3 protein, human; C489197:Fgf3 protein, mouse; D051518:Fibroblast Growth Factor 3; D019913:Nuclear Localization Signals; D011500:Protein Synthesis Inhibitors; D011518:Proto-Oncogene Proteins; D005346:Fibroblast Growth Factors; D003513:Cycloheximide; D011770:Pyruvate Kinase; D011505:Protein-Tyrosine Kinases; D001616:beta-Galactosidase