title: Human neuroblastoma SH-SY5Y cells show increased resistance to hyperthermic stress after differentiation, associated with elevated levels of Hsp72.
abstract: OBJECTIVE
  Terminally differentiated neurones in the central nervous system need to be protected from stress. We ask here whether differentiation of progenitor cells to neurones is accompanied by up-regulation of Hsp72, with acquisition of enhanced thermotolerance.
  
  
  METHODS
  Human neuroblastoma SH-SY5Y cells were propagated in an undifferentiated form and subsequently differentiated into neurone-like cells. Thermotolerance tests were carried out by exposure of cells to various temperatures, monitoring nuclear morphology as index of cell death. Abundance of Hsp72 was measured in cell lysates by western immunoblotting.
  
  
  RESULTS
  The differentiation of SH-SY5Y cells was accompanied by increased expression of Hsp72. Further, in both cell states, exposure to mild hyperthermic stress (43°C for 30 min) increased Hsp72 expression. After differentiation, SH-SY5Y cells were more resistant to hyperthermic stress compared to their undifferentiated state, correlating with levels of Hsp72. Stable exogenous expression of Hsp72 in SH-SY5Y cells (transfected line 5YHSP72.1, containing mildly elevated levels of Hsp72), led to enhanced resistance to hyperthermic stress. Hsp72 was found to be inducible in undifferentiated 5YHSP72.1 cells; such heat-treated cells displayed enhanced thermotolerance. Treatment of cells with KNK437, a suppressor of Hsp72 induction, resulted in acute thermosensitisation of all cell types tested here.
  
  
  CONCLUSIONS
  Hsp72 has a major role in the enhanced hyperthermic resistance acquired during neuronal differentiation of SH-SY5Y cells. These findings model the requirement in intact organisms for highly differentiated neurones to be specially protected against thermal stress.
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University , Clayton , Victoria.
authors.forename: Lesley
authors.initials: L
authors.lastname: Cheng
authors.forename: Danielle J
authors.initials: DJ
authors.lastname: Smith
authors.forename: Robin L
authors.initials: RL
authors.lastname: Anderson
authors.forename: Phillip
authors.initials: P
authors.lastname: Nagley
mesh_terms: D001559:Benzhydryl Compounds / Q000494:pharmacology; D002454:Cell Differentiation / Q000502:physiology; D045744:Cell Line, Tumor; D050884:HSP72 Heat-Shock Proteins / Q000096:biosynthesis / Q000378:metabolism*; D006801:Humans; D009447:Neuroblastoma / Q000378:metabolism*; D009474:Neurons / Q000502:physiology; D011760:Pyrrolidinones / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: D001559:Benzhydryl Compounds; D050884:HSP72 Heat-Shock Proteins; C410027:KNK 437; D011760:Pyrrolidinones