Effect of fibroblast growth factor-1 on the expression of early growth response-1 in human periodontal ligament cells.
OBJECTIVE
Early growth response-1 is a nuclear transcription factor implicated in regulating cell proliferation. Fibroblast growth factor-1 is the prototypic fibroblast growth factor involved in the proliferation and differentiation of various cell types. Expression of early growth response-1 induced by fibroblast growth factor-1 thus may be very important for cell growth, during both development and wound healing in oral tissue. However, little is known about the expression and kinetics of early growth response-1 in fibroblast growth factor-1-stimulated oral cells. The aim of this study was to investigate the effects of fibroblast growth factor-1 on the expression of early growth response-1 in human periodontal ligament cells.


METHODS
Periodontal ligament cells were cultured in medium containing 1, 10 or 100 ng/mL of fibroblast growth factor-1 for 45 min or with 10 ng/mL of fibroblast growth factor-1 for 15, 30, 45, 60 or 120 min. The proliferation of periodontal ligament cells was evaluated by measuring 5-bromo-2'-deoxyuridine incorporation. The expression of early growth response-1 mRNA and protein, and the localization of early growth response-1 protein, were examined by western blotting, northern blotting and immunocytostaining.


RESULTS
5-Bromo-2'-deoxyuridine incorporation correlated directly with increases in fibroblast growth factor-1 concentration, and 5-bromo-2'-deoxyuridine incorporation peaked 45 min after starting treatment. Early growth response-1 protein was expressed in response to a concentration of fibroblast growth factor-1 as low as 1 ng. Peak expression of early growth response-1 mRNA was observed at 15 min and that of early growth response-1 protein at 60 min. The 140-kDa early growth response-1 protein was not detected in the nuclear fraction, and the peak expression of the 80-kDa early growth response-1 protein occurred at 60 min. Early growth response-1 localized in or around the nucleus at 30 min.


CONCLUSIONS
These results show that a concentration of fibroblast growth factor-1 as low as 1 ng induces the expression of early growth response-1 protein, and that the 80-kDa early growth response-1 protein functions in the nucleus of periodontal ligament cells treated with fibroblast growth factor-1.
Tamura
I
I
Department of Biochemistry, Osaka Dental University, Osaka, Japan. tamura@cc.osaka-dent.ac.jp
Chaqour
B
B
Howard
P S
PS
Ikeo
T
T
Macarak
E J
EJ
D015152:Blotting, Northern; D015153:Blotting, Western; D049109:Cell Proliferation; D002478:Cells, Cultured; D051766:Early Growth Response Protein 1 / Q000096:biosynthesis*; D016220:Fibroblast Growth Factor 1 / Q000494:pharmacology / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D010513:Periodontal Ligament / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis
C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D012333:RNA, Messenger; D016220:Fibroblast Growth Factor 1