Figure 1.

The compression-dependent upregulation of ephrin-A2 in PDL is accompanied by ERK1/2 activation and the transcriptional induction of c-fos. We confirmed our previously reported data and showed compression-dependent upregulation of ephrin-A2 and EphA2 in a primary periodontal ligament (PDL) fibroblast population (PDLF III) (A, B). Primary human PDLFs (PDLF I, II, III) were subjected to compression (30.3 g/cm²) for 1, 4, 6 h. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis revealed a significant upregulation of c-fos in compressed PDLF I, II, and III (D, F, H). Significant upregulation of c-fos preceded the upregulation of ephrin-A2. The regulation of ephrin-A2 and c-fos, respectively, upon the application of compressive forces was confirmed on the protein level for PDLF I, II, and III (C, E, G, lower panels). For comparability, the Western blots were stripped and reprobed. Tubulin was used as a loading control. Compression experiments were performed in triplicates (n = 3). Static cells, time matched, served as controls. The qRT-PCR assays were performed in triplicates. Data are presented as mean ± SD. *P < 0.05 vs. control (one-way analysis of variance, Dunnett’s post hoc test).