Characterization of fibroblast growth factor-6 expressed by Chinese hamster ovary cells as a glycosylated mitogen for human vascular endothelial cells.
The gene for fibroblast growth factor (FGF)-6/hst-2 was originally identified by its close homology with the FGF-4/hst-1 gene. Aside from its ability to transform cultured fibroblasts, the characteristics of FGF-6 protein have only been studied using a simple preparation from E. coli. In the present study, we expressed FGF-6 cDNA in CHO cells and characterized the resultant protein. We found that CHO cells secreted several forms of the FGF-6 polypeptide, and that there were multiple N-terminal modifications. The longest form (18-kDa) contained the sequence, SerProAlaGlyAlaArg, as its N-terminus, which was consistent with the signal peptide cleavage site predicted from its primary structure. The core polypeptide was primarily modified by heterogeneous N-glycans that were sialylated to a small degree; among them, biantennary structures were found to predominate. Moreover, possible O-glycosylation was also detected. N-glycosylated FGF-6 potently induced DNA synthesis and proliferation of human vascular endothelial cells, whereas in the absence of N-glycosylation, FGF-6 mitogenicity was substantially diminished. The results clearly indicate that FGF-6 expressed by mammalian cells is a glycosylated mitogen for vascular endothelial cells and further suggests that N-glycosylation plays a key role in determining the mitogenicity of FGF-6.
Asada
M
M
Biosignaling Department, National Institute of Bioscience and Human Technology, Ibaraki, Japan.
Yoneda
A
A
Oda
Y
Y
Ota
K
K
Ozawa
K
K
Fukuta
K
K
Omae
F
F
Asanagi
M
M
Orikasa
N
N
Suzuki
M
M
Oka
S
S
Makino
T
T
Imamura
T
T
D000818:Animals; D016466:CHO Cells / Q000378:metabolism*; D006224:Cricetinae; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects*; D051522:Fibroblast Growth Factor 6; D005346:Fibroblast Growth Factors; D015870:Gene Expression; D006031:Glycosylation; D006801:Humans; D008934:Mitogens / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000235:genetics*; D014471:Umbilical Veins / Q000166:cytology
C496452:FGF6 protein, human; D051522:Fibroblast Growth Factor 6; D008934:Mitogens; D011518:Proto-Oncogene Proteins; D005346:Fibroblast Growth Factors