title: Hypothermia inhibits Fas-mediated apoptosis of primary mouse hepatocytes in culture.
abstract: Apoptosis occurs during the isolation and even short-term storage and culture of hepatocytes, and in the pathogenesis of liver diseases, such as hepatic failure and hepatitis. Therapeutic hypothermia has beneficial effects in experimental models of fulminant hepatic failure. The mechanisms underlying the potential benefits of mild hypothermia on the liver have not been well investigated. We examined the effects of temperature on soluble Fas ligand-induced apoptosis in freshly isolated mouse hepatocytes. Decreasing the culture temperature from 37 degrees C to 32 degrees C produced significant suppression of Fas-mediated apoptosis in cultured hepatocytes over a 12-h period. This observation was supported by cell morphology, flow cytometry analysis of cellular DNA content, and Annexin V-FITC staining of membrane phosphatidylserine translocation. In hypothermic conditions, Fas-mediated cytochrome c release from mitochondria of hepatocytes and the proximate downstream activation of caspase-9 were suppressed under mild hypothermic conditions. Effector caspase-7 activity was also inhibited at 32 degrees C. In contrast, the activation of initiator caspase-8 and cleavage of Bid were not affected after Fas-ligand stimulation. These findings suggest that mild hypothermia suppresses Fas-mediated apoptosis of liver cells by the partial inhibition of signaling events including mitochondrial damage, cytochrome c release, and subsequent apoptosome formation and effector caspase activation.
authors.affiliation: Department of Pediatrics, Northwestern University Feinberg School of Medicine and Children's Memorial Institute for Education and Research, Chicago, IL 60611, USA. t-fu@northwestern.edu
authors.forename: Tao
authors.initials: T
authors.lastname: Fu
authors.forename: Andres T
authors.initials: AT
authors.lastname: Blei
authors.forename: Noriaki
authors.initials: N
authors.lastname: Takamura
authors.forename: Tesu
authors.initials: T
authors.lastname: Lin
authors.forename: Danqing
authors.initials: D
authors.lastname: Guo
authors.forename: Honglin
authors.initials: H
authors.lastname: Li
authors.forename: Maurice R
authors.initials: MR
authors.lastname: O'Gorman
authors.forename: Humberto E
authors.initials: HE
authors.lastname: Soriano
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D020169:Caspases / Q000378:metabolism / Q000502:physiology; D002448:Cell Adhesion / Q000187:drug effects; D002467:Cell Nucleus / Q000737:chemistry; D002478:Cells, Cultured; D003080:Cold Temperature; D004247:DNA / Q000032:analysis; D053222:Fas Ligand Protein; D005260:Female; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010718:Phosphatidylserines / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology; D019014:fas Receptor / Q000502:physiology*
chemical_list: D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D008562:Membrane Glycoproteins; D010718:Phosphatidylserines; D019014:fas Receptor; D019284:Thapsigargin; D004247:DNA; D020169:Caspases