Abstract
To evaluate age-related differences in the expression of heat shock protein (HSP) 27 in periodontal ligament (PDL) cells at the protein and mRNA levels, we obtained PDL cells from the incisors of rats weighing approximately 150 g (young group) and 350 g (aged group) and seeded the cells in culture dishes. Over 2 weeks of cultivation, PDL cells were subjected to quantitative reverse transcription polymerase chain reaction (RT-PCR) to measure HSP27 mRNA, and HSP27 protein expression was examined by immunofluorescence. HSP27 mRNA expression in the young group increased slightly over the 2 weeks, while in the aged group it increased significantly over the same time period. The expression ratio of HSP27 mRNA in the aged group was higher than in the young group at 14 days. Furthermore, immunofluorescence signals for HSP27 were stronger in the aged group than in the young group. These data reveal that PDL cells vary their expression of HSP27 with age, and suggest that in view of such changes in HSP27 mRNA expression, the self-defense mechanism is enhanced in aged PDL cells although their overall homeostatic conditions are suppressed.
