Hsp72 inhibits Fas-mediated apoptosis upstream of the mitochondria in type II cells.
Heat shock protein 72 (Hsp72) inhibits apoptosis induced by some stresses that trigger the intrinsic apoptosis pathway. However, with the exception of TNFalpha-induced apoptosis, a role for Hsp72 in modulating the extrinsic pathway of apoptosis has not been clearly established. In this study, it was demonstrated that Hsp72 could inhibit Fas-mediated apoptosis of type II CCRF-CEM cells, but not type I SW480 or CH1 cells. Similar results were obtained when Fas ligand or an agonistic Fas antibody initiated the Fas apoptosis pathway. In CCRF-CEM cells, Hsp72 inhibited mitochondrial membrane depolarization and cytochrome c release but did not alter surface Fas expression or processing of caspase-8 and Bid, indicating that Hsp72 acts upstream of the mitochondria to inhibit Fas-mediated apoptosis. Thus, the ability of Hsp72 to inhibit Fas-mediated apoptosis is limited to type II cells where involvement of the intrinsic pathway is required for efficient effector caspase activation.
Clemons
Nicholas J
NJ
Cancer Biology Laboratory, Peter MacCallum Cancer Centre, St Andrew's Place, East Melbourne 3002, Victoria, Australia.
Buzzard
Katherine
K
Steel
Rohan
R
Anderson
Robin L
RL
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000502:physiology*; D006801:Humans; D008928:Mitochondria / Q000502:physiology*; D019014:fas Receptor / Q000502:physiology*
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D019014:fas Receptor; D020169:Caspases