title: Puma indirectly activates Bax to cause apoptosis in the absence of Bid or Bim.
abstract: Bcl-2 family members regulate apoptosis in response to cytokine withdrawal and a broad range of cytotoxic stimuli. Pro-apoptotic Bcl-2 family members Bax and Bak are essential for apoptosis triggered by interleukin-3 (IL-3) withdrawal in myeloid cells. The BH3-only protein Puma is critical for initiation of IL-3 withdrawal-induced apoptosis, because IL-3-deprived Puma(-/-) cells show increased capacity to form colonies when IL-3 is restored. To investigate the mechanisms of Puma-induced apoptosis and the interactions between Puma and other Bcl-2 family members, we expressed Puma under an inducible promoter in cells lacking one or more Bcl-2 family members. Puma rapidly induced apoptosis in cells lacking the BH3-only proteins, Bid and Bim. Puma expression resulted in activation of Bax, but Puma killing was not dependent on Bax or Bak alone as Puma readily induced apoptosis in cells lacking either of these proteins, but could not kill cells deficient for both. Puma co-immunoprecipitated with the anti-apoptotic Bcl-2 family members Bcl-x(L) and Mcl-1 but not with Bax or Bak. These data indicate that Puma functions, in the context of induced overexpression or IL-3 deprivation, primarily by binding and inactivating anti-apoptotic Bcl-2 family members.
authors.affiliation: Children's Cancer Centre, Murdoch Children's Research Institute, Royal Children's Hospital, Flemington Road, Parkville, Victoria, Australia. anissa.jabbour@mcri.edu.au
authors.forename: A M
authors.initials: AM
authors.lastname: Jabbour
authors.forename: J E
authors.initials: JE
authors.lastname: Heraud
authors.forename: C P
authors.initials: CP
authors.lastname: Daunt
authors.forename: T
authors.initials: T
authors.lastname: Kaufmann
authors.forename: J
authors.initials: J
authors.lastname: Sandow
authors.forename: L A
authors.initials: LA
authors.lastname: O'Reilly
authors.forename: B A
authors.initials: BA
authors.lastname: Callus
authors.forename: A
authors.initials: A
authors.lastname: Lopez
authors.forename: A
authors.initials: A
authors.lastname: Strasser
authors.forename: D L
authors.initials: DL
authors.lastname: Vaux
authors.forename: P G
authors.initials: PG
authors.lastname: Ekert
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D051023:BH3 Interacting Domain Death Agonist Protein / Q000235:genetics / Q000378:metabolism*; D000072224:Bcl-2-Like Protein 11; D002460:Cell Line; D002470:Cell Survival / Q000235:genetics; D002478:Cells, Cultured; D045304:Cytochromes c / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D015151:Immunoblotting; D047468:Immunoprecipitation; D007377:Interleukin-3 / Q000172:deficiency / Q000502:physiology; D053078:Membrane Potential, Mitochondrial / Q000235:genetics / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; D051023:BH3 Interacting Domain Death Agonist Protein; C494827:Bax protein, mouse; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; C494815:Bid protein, mouse; D007377:Interleukin-3; D008565:Membrane Proteins; C488588:PUMA protein, mouse; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c