title: The short prodomain influences caspase-3 activation in HeLa cells.
abstract: Proteolytic activation of caspases is a key step in the process of apoptosis. According to their primary structure, caspases can be divided into a group with a long prodomain and a group with a short prodomain. Whereas long prodomains play a role in autocatalytic processing, little is known about the function of the short prodomain, for example the prodomain of caspase-3. We constructed caspase-3 variants lacking the prodomain and overexpressed these in HeLa and yeast cells. We found that removal of the caspase-3 prodomain resulted in spontaneous proteolytic activation of the protein when expressed in HeLa cells. This processing was only partially autocatalytic, as demonstrated by a catalytically inactive caspase-3 mutant. Co-expression of the anti-apoptotic protein XIAP (X-chromosome-linked inhibitor of apoptosis protein) completely blocked the observed spontaneous activation, which excluded a direct involvement of caspase-8. Our findings indicate that the short prodomain of caspase-3 serves as a silencing component in mammalian cells by retaining this executioner caspase in an inactive state.
authors.affiliation: Biochemical Pharmacology, Faculty of Biology, University of Konstanz, POB 5560-M 668, D 78434 Konstanz, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Meergans
authors.forename: A K
authors.initials: AK
authors.lastname: Hildebrandt
authors.forename: D
authors.initials: D
authors.lastname: Horak
authors.forename: C
authors.initials: C
authors.lastname: Haenisch
authors.forename: A
authors.initials: A
authors.lastname: Wendel
mesh_terms: D017209:Apoptosis; D015153:Blotting, Western; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000737:chemistry / Q000378:metabolism*; D002384:Catalysis; D002460:Cell Line; D018076:DNA, Complementary / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D006367:HeLa Cells; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism; D014162:Transfection; D051636:X-Linked Inhibitor of Apoptosis Protein
chemical_list: D018076:DNA, Complementary; D011506:Proteins; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D008156:Luciferases; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases