A carboxyl-terminal domain in fibroblast growth factor (FGF)-2 inhibits FGF-1 release in response to heat shock in vitro.
The fibroblast growth factor (FGF) prototypes, FGF-1 and FGF-2, lack a signal sequence, but both contain a nuclear localization sequence. We prepared a series of FGF-1 deletion mutants fused to the reporter gene, beta-galactosidase (beta-gal) and determined that a domain between residues 83 and 154 is responsible for FGF-1 cytosol retention in NIH 3T3 cells. Using a series of FGF-beta-gal chimeric proteins prepared by the shuffling of cassette-formatted synthetic FGF prototype genes, we were able to demonstrate that the nuclear localization sequence from the 5'-CUG region of FGF-2 is not able to direct the nuclear association of FGF-1 due to its inability to repress the function of the FGF-1 cytosol retention domain. We also observed that while the FGF-1:beta-gal chimera was released in response to heat shock, the FGF-2:beta-gal protein was not. Further, replacement of the FGF-1 cytosol retention domain with the corresponding domain from FGF-2 repressed the release of the chimeric protein. These data suggest that the specificity of the stress-induced secretion pathway for FGF-1 involves a carboxyl-terminal domain that is absent in FGF-2 and that the FGF-1 secretion pathway does not restrict the release of high molecular weight forms of FGF-1.
Shi
J
J
Department of Molecular Biology, Holland Laboratory, American Red Cross, Rockville, Maryland 20855, USA.
Friedman
S
S
Maciag
T
T
D016475:3T3 Cells; D000818:Animals; D016220:Fibroblast Growth Factor 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000737:chemistry* / Q000378:metabolism; D006358:Hot Temperature; D051379:Mice; D008970:Molecular Weight; D016297:Mutagenesis, Site-Directed; D016366:Open Reading Frames; D010957:Plasmids / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017384:Sequence Deletion; D013329:Structure-Activity Relationship
D011993:Recombinant Fusion Proteins; D016222:Fibroblast Growth Factor 2; D016220:Fibroblast Growth Factor 1