Transcriptional regulation of bone sialoprotein gene by CO₂ laser irradiation

Abstract

Bone sialoprotein (BSP), an early marker of osteoblast differentiation, has been implicated in the nucleation of hydroxyapatite during de novo bone formation. Low-power laser irradiation has a stimulating effect on cells and tissues. Although the carbon dioxide (CO₂) laser is a hard surgical laser, we have attempted to use it at low energy density to achieve biological alterations. To investigate the effects of CO₂ laser irradiation on BSP gene transcription, we used rat osteoblast-like ROS17/2.8 cells. BSP mRNA levels were increased at 12 h after irradiation with the CO₂ laser (2 W, 20 s). Transient transfection assays using various sizes of the rat BSP gene promoter linked to the luciferase reporter gene showed that CO₂ laser irradiation induced luciferase activity of a -116 to +60 BSP promoter construct (pLUC3) at 12 h in the cells. Transcriptional stimulation by CO₂ laser irradiation was abrogated in the pLUC3 construct containing a 2-bp mutation in the fibroblast growth factor 2 response element (FRE). Gel shift analyses showed that CO₂ laser irradiation increased the binding of nuclear protein to FRE. These studies demonstrate that CO₂ laser irradiation increases BSP transcription via FRE in the rat BSP gene promoter. (J Oral Sci 53, 51-59, 2011)