Heat stress induces alkaline phosphatase activity and heat shock protein 25 expression in cultured pulp cells.
OBJECTIVE
To investigate the responses of cultured rat pulp cells to heat stress.


METHODS
Pulp cells were obtained from rat incisors and cultured at 37 degrees C. The cells were cultured at 42 degrees C for 30 min and then cultured at 37 degrees C again. Morphology, alkaline phosphatase (ALP) activity and expression of heat shock protein 25 (HSP25) were investigated at 0, 1, 3, 5, 7, 10 and 14 days following stimulation. As a control, the cells were maintained at 37 degrees C.


RESULTS
Although there were few cells of apoptosis immediately after heat stress, there were mitotic cells from day 1 after heat stress. ALP activity in the heat stress group significantly increased at days 7 and 14 compared with the control group (about 1.7-fold, P < 0.01, Friedman test). HSP25 expression increased in both groups, with HSP25 in the heat stress group being expressed earlier than in the control group, and nuclear localization of HSP25 was observed at days 0 and 1 in heat-stressed cells.


CONCLUSIONS
These results suggest that heat stress not only induces HSP25 but also enhances ALP activity in pulp cells.
Department of Pathology, Tokyo Dental College, Chiba, Japan.
M-W
MW
Lee
T
T
Muramatsu
T
T
Uekusa
J-H
JH
Lee
M
M
Shimono
D000469:Alkaline Phosphatase / Q000032:analysis*; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D015415:Biomarkers / Q000032:analysis; D015153:Blotting, Western; D002467:Cell Nucleus / Q000648:ultrastructure; D002478:Cells, Cultured; D003124:Colorimetry; D003782:Dental Pulp / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*; D005455:Fluorescent Antibody Technique; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000032:analysis*; D018869:Heat-Shock Response / Q000502:physiology; D006358:Hot Temperature; D008938:Mitosis / Q000502:physiology; D009363:Neoplasm Proteins / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D015415:Biomarkers; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C486114:Hspb1 protein, rat; D009363:Neoplasm Proteins; D000469:Alkaline Phosphatase