Expression of Early Growth Response in Human Oral Fibroblast

Objectives:The early growth response (EGR) gene family encodes for nuclear transcription factors that are implicated in regulating cell proliferation. There is little information on their expression in oral tissues. Methods:We have investigated the expression of EGR-1 and -2 proteins and mRNAs in human periodontal ligament fibroblast (PLF) and pulpal fibroblast (PUF) using Western blotting, Northern blotting and FITC-labeled immunocytochemical techniques. After cultivating both cell lines in Dulbecco's modified Eagle's medium (DME) for two days without serum, we incubated them in DME supplemented 10% fetal calf serum (FCS) for 15, 30, 45, 60 and 120 min. Results:Measurement of 5-bromo 2'-deoxyuridine incorporation showed a peak in both cells treated for 45 min. In PLF, expressions of EGR-1 protein and mRNA were seen beginning 15 min after treatment, and anti-EGR-1 antibody strongly reacted with the nuclear region at 30 min. Maximum expression of EGR-2 protein was seen at 30min and EGR-2 localized in and around the nucleus. Expression of EGR-2 mRNA showed a peak at 15 min. In PUF, expressions of EGR-1 protein and mRNA were seen beginning 15 min after treatment and EGR-1 protein gradually increased. Anti-EGR-1 antibody strongly reacted with the nuclear region at 30 min. Maximum expression of EGR-2 was seen at 60 min and EGR-2 distributed in and around the nucleus at 30 min. Expression of EGR-2 mRNA showed a peak at 15 min. Conclusions:These results demonstrate that EGR expression is more pronounced in stimulated human oral fibroblasts and that EGR family plays a potentially important role in cell growth. This study was supported by a Grant-in-Aid for Young Scientists (B) from the Ministry of Education, Culture, Sports, Science and Technology (No. 14771033). tamura@cc.osaka-dent.ac.jp