2019 年 53 巻 1 号 p. 25-30
Early growth response (EGR)‐1 is a 80 kDa protein with a zinc‐finger motif that functions as a DNA transcription factor, and contributes to cell growth. We investigated the kinetics of EGR‐1 in human dental pulpal cells stimulated with insulin‐like growth factor (IGF)‐1. Human pulpal cells were cultured with Dulbecco's modified Eagle Medium (DMEM) with 10% fetal calf serum (FCS). After cultivation in DMEM without FCS for two days, pulpal cells were incubated with DMEM containing 1, 10 or 100 ng/mL of IGF‐1 for 30 min as an initial experiment. In the dose‐response experiments, the proliferation index of these cells, as measured by 5‐bromo‐2'‐deoxyuridine incorporation, increased gradually in the presence of IGF‐1. Then, after cultivation in DMEM without FBS for two days, pulpal cells were incubated with DMEM containing 10 ng/mL of IGF‐1 for 15, 30, 45 or 60 min, respectively. In the time‐course experiments, pulpal cells that were cultured with IGF‐1 expressed EGR‐1 mRNA from 15 min and EGR‐1 protein from 30 min. DMEM supplemented with 10 ng/mL IGF‐1 clearly induced the expression of EGR‐1 in pulpal cells. Immunocytochemical observations by the reactions of FITC revealed strong nuclear immunostaining for EGR‐1 in pulpal cells treated with IGF‐1 for 30 min. These results suggest that EGR‐I has a potentially important role in pulpal cell growth, and that IGF‐1 induces the expression of EGR‐I in pulpal cells. (J Osaka Dent Univ 2019; 53: 25‐30)
