title: Stress-mediated signaling in PC12 cells - the role of the small heat shock protein, Hsp27, and Akt in protecting cells from heat stress and nerve growth factor withdrawal.
abstract: We have investigated the role of stress-activated signaling pathways and the small heat shock protein, Hsp27, in protecting PC12 cells from heat shock and nerve growth factor (NGF) withdrawal-induced apoptosis. PC12 cells and a stable cell line overexpressing Hsp27 (HSPC cells) were subjected to heat shock. This resulted in the rapid activation of Akt followed by p38 mitogen-activated protein kinase (MAPK) signaling, with phosphorylation and intracellular translocation of Hsp27 also detectable. Hsp27 was found to form an immunoprecipitable complex with Akt and p38 MAPK in both non-stimulated and heat shocked cells, although after heat shock there was a gradual dissociation of Akt and p38 from the Hsp27. Cells were differentiated with NGF and then subjected to NGF withdrawal, a treatment which results in substantial cell death over 24-72 h. Hsp27 was shown to be protective against this treatment, since HSPC cells which overexpress Hsp27 showed significantly less cell death than the parental PC12 cells. In addition, we observed that phosphorylation of Akt was maintained in HSPC cells subjected to heat shock and NGF withdrawal compared with the parental cells. Taken together, our results suggest that Hsp27 may protect Akt from dephosphorylation and may also act in stabilizing Akt.
authors.affiliation: Division of Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St John's, Newfoundland, Canada. kmearow@mun.ca
authors.forename: K M
authors.initials: KM
authors.lastname: Mearow
authors.forename: M E
authors.initials: ME
authors.lastname: Dodge
authors.forename: M
authors.initials: M
authors.lastname: Rahimtula
authors.forename: C
authors.initials: C
authors.lastname: Yegappan
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D004789:Enzyme Activation / Q000502:physiology; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018869:Heat-Shock Response / Q000502:physiology; D006358:Hot Temperature; D007150:Immunohistochemistry; D008164:Luminescent Proteins / Q000235:genetics; D046911:Macromolecular Substances; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009363:Neoplasm Proteins / Q000502:physiology*; D020932:Nerve Growth Factor / Q000172:deficiency / Q000494:pharmacology*; D018696:Neuroprotective Agents / Q000378:metabolism / Q000494:pharmacology; D016716:PC12 Cells; D010766:Phosphorylation; D011233:Precipitin Tests; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013312:Stress, Physiological / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C486114:Hspb1 protein, rat; D008164:Luminescent Proteins; D046911:Macromolecular Substances; D009363:Neoplasm Proteins; D018696:Neuroprotective Agents; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D020932:Nerve Growth Factor; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases