Effect of carnosine on runt-related transcription factor-2/core binding factor α-1 and Sox9 expressions of human periodontal ligament cells

Background: Previous studies have reported that beta-alanyl-L-histidine (carnosine) enhanced the process of wound healing by stimulating effusion at the initial stage of inflammation, and also enhanced runt-related transcription factor-2/core binding factor alpha-1 (RUNX2/Cbfa1), Sox9, bone morphogenetic protein-2 (BMP-2) and BMP-7 expressions of human periodontal ligament cells. Objectives: In order to clarify the relationship between RUNX2/Cbfa1 or Sox9 expressions and BMP-2 or BMP-7 expressions enhanced by carnosine, we determined the effect of carnosine on the expression of BMP receptors and activation of their downstream signaling molecules in human periodontal ligament cells. Material and methods: Human periodontal ligament cells were cultured with alpha-minimum essential medium containing 10% fetal bovine serum with or without 10(-4) or 10(-5) M carnosine for up to 10 days. The gene expression of BMP receptors, RUNX2/Cbfa1 and Sox9 was measured using semiquantitative reverse transcription-polymerase chain reaction. Phosphorylation of Smad1 was determined using a western blot analysis. Results: Alkaline phosphatase activity increased in cultures with carnosine. Among the BMP receptors, expression of ActR-I and BMPR-II increased in cultures with carnosine, whereas expression of BMPR-IA, BMPR-IB, ActR-IIA and ActR-IIB was not affected. Culture with carnosine increased phosphorylation of Smad1, a signal-transducing molecule for BMP-2 and BMP-7. Noggin reduced carnosine-induced up-regulation of RUNX2/Cbfa1 and Sox9 mRNA, suggesting that BMPs were responsible for up-regulating RUNX2/Cbfa1 gene expression in human periodontal ligament cells. Conclusion: These results suggest that carnosine enhance RUNX2/Cbfa1 and Sox9 expression of human periodontal ligament cells via the autocrine action of BMP-2 or BMP-7 produced by the cells.