title: Baculovirus P35 inhibits the glucocorticoid-mediated pathway of cell death.
abstract: Recent evidence suggests that members of the interleukin-1-beta-converting enzyme (ICE)/Ced-3 family are key mediators of mammalian apoptosis. The known members of the ICE/Ced-3 cysteine protease family are synthesized as proenzymes and require proteolytic processing to produce active, heterodimeric enzymes. The baculovirus protein P35 has recently been shown to inhibit several members of the ICE/Ced-3 cysteine protease family. The importance of ICE/Ced-3 cysteine proteases in programmed cell death prompted us to investigate the role of the apoptotic mediator, CPP32, in the glucocorticoid-mediated cell death pathway. Glucocorticoids induce growth inhibition and apoptosis in sensitive leukemic cell lines, immature thymocytes, and eosinophils. In this report, we demonstrate the enzymatic cleavage of proCPP32 to its active subunits in cells undergoing glucocorticoid-induced apoptotic cell death. Concurrently, in apoptotic cells, PARP, a 116-kilodalton (kDa) human poly(ADP-ribose) polymerase, is proteolytically cleaved to its signature 85-kDa fragment. The proteolytic processing of PARP (the nuclear DNA repair enzyme known to be cleaved in association with apoptosis) is catalyzed by members of the ICE/Ced-3 family. Importantly, stable transfection of the antiapoptotic baculovirus P35 inhibits glucocorticoid-induced apoptotic cell death, proteolytic processing of proCPP32, and cleavage of the 116kDa PARP. We conclude that activation of CPP32 is a critical event in glucocorticoid-induced apoptosis and that this pathway is inhibited at or upstream of CPP32 by baculovirus P35. These data demonstrate that PARP cleavage occurs during glucocorticoid-induced apoptotic cell death and show that this proteolytic process is blocked by the expression of baculovirus P35, supporting a role for activation of the ICE/Ced-3-like cysteine protease during glucocorticoid-induced apoptosis.
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
authors.forename: N M
authors.initials: NM
authors.lastname: Robertson
authors.forename: J
authors.initials: J
authors.lastname: Zangrilli
authors.forename: T
authors.initials: T
authors.lastname: Fernandes-Alnemri
authors.forename: P D
authors.initials: PD
authors.lastname: Friesen
authors.forename: G
authors.initials: G
authors.lastname: Litwack
authors.forename: E S
authors.initials: ES
authors.lastname: Alnemri
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins; D053148:Caspase 3; D020169:Caspases; D002455:Cell Division; D003546:Cysteine Endopeptidases / Q000378:metabolism* / Q000502:physiology*; D015853:Cysteine Proteinase Inhibitors / Q000502:physiology; D053938:DNA Fragmentation; D004789:Enzyme Activation; D005938:Glucocorticoids / Q000494:pharmacology; D015801:Helminth Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D015452:Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics / Q000473:pathology; D014407:Tumor Cells, Cultured; D014764:Viral Proteins / Q000502:physiology*
chemical_list: D029742:Caenorhabditis elegans Proteins; D015853:Cysteine Proteinase Inhibitors; D005938:Glucocorticoids; D015801:Helminth Proteins; D051034:Inhibitor of Apoptosis Proteins; D014764:Viral Proteins; C086430:inhibitor of apoptosis, Nucleopolyhedrovirus; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D003546:Cysteine Endopeptidases; C089223:ced-3 protein, C elegans