title: Continuous fever-range heat stress induces thermotolerance in odontoblast-lineage cells.
abstract: OBJECTIVE
  Heat shock during restorative procedures can trigger damage to the pulpodentin complex. While severe heat shock has toxic effects, fever-range heat stress exerts beneficial effects on several cells and tissues. In this study, we examined whether continuous fever-range heat stress (CFHS) has beneficial effects on thermotolerance in the rat clonal dental pulp cell line with odontoblastic properties, KN-3.
  
  
  METHODS
  KN-3 cells were cultured at 41°C for various periods, and the expression level of several proteins was assessed by Western blot analysis. After pre-heat-treatment at 41°C for various periods, KN-3 cells were exposed to lethal severe heat shock (LSHS) at 49°C for 10min, and cell viability was examined using the MTS assay. Additionally, the expression level of odontoblast differentiation makers in surviving cells was examined by Western blot analysis.
  
  
  RESULTS
  CFHS increased the expression levels of several heat shock proteins (HSPs) in KN-3 cells, and induced transient cell cycle arrest. KN-3 cells, not pre-heated or exposed to CFHS for 1 or 3h, died after exposure to LSHS. In contrast, KN-3 cells exposed to CFHS for 12h were transiently lower on day 1, but increased on day 3 after LSHS. The surviving cells expressed odontoblast differentiation markers, dentine sialoprotein and dentine matrix protein-1. These results suggest that CFHS for 12h improves tolerance to LSHS by inducing HSPs expression and cell cycle arrest in KN-3 cells.
  
  
  CONCLUSIONS
  The appropriate pretreatment with continuous fever-range heat stress can provide protection against lethal heat shock in KN-3 cells.
authors.affiliation: Division of Endodontics and Restorative Dentistry, Department of Oral Functions, Kyushu Dental University, Kitakyushu, Japan. Electronic address: morotomi@kyu-dent.ac.jp.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Morotomi
authors.affiliation: Division of Endodontics and Restorative Dentistry, Department of Oral Functions, Kyushu Dental University, Kitakyushu, Japan.
authors.forename: Chiaki
authors.initials: C
authors.lastname: Kitamura
authors.affiliation: Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, Kitakyushu, Japan.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Okinaga
authors.affiliation: Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, Kitakyushu, Japan.
authors.forename: Tatsuji
authors.initials: T
authors.lastname: Nishihara
authors.affiliation: Section of Periodontology, Department of Odontology, Fukuoka Dental College, Fukuoka, Japan.
authors.forename: Ryuji
authors.initials: R
authors.lastname: Sakagami
authors.affiliation: Section of Operative Dentistry and Endodontology, Department of Odontology, Fukuoka Dental College, Fukuoka, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Anan
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D015153:Blotting, Western; D002453:Cell Cycle / Q000502:physiology; D002470:Cell Survival; D002478:Cells, Cultured; D002999:Clone Cells; D006360:Heat-Shock Proteins / Q000378:metabolism*; D018869:Heat-Shock Response / Q000502:physiology*; D006358:Hot Temperature; D020287:In Situ Nick-End Labeling; D009804:Odontoblasts / Q000502:physiology*; D051381:Rats; D013312:Stress, Physiological / Q000502:physiology
chemical_list: D006360:Heat-Shock Proteins
keywords: Cell cycle arrest; Dental pulp; Heat shock protein; Hyperthermia; Odontoblast; Restorative procedure.; Thermotolerance