title: Bcl-2 and Bax modulate adenine nucleotide translocase activity.
abstract: Bcl-2 is a prosurvival factor that reportedly prevents the nonspecific permeabilization of mitochondrial membranes, yet enhances specific ADP/ATP exchange by these organelles. Here, we show that Bcl-2 enhances the ADP/ATP exchange in proteoliposomes containing the purified adenine nucleotide translocase (ANT) in isolated mitochondria and mitoplasts, as well as in intact cells in which mitochondrial matrix ATP was monitored continuously using a specific luciferase-based assay system. Conversely, Bax, which displaces Bcl-2 from ANT in apoptotic cells, inhibits ADP/ATP exchange through a direct action on ANT. The Bax-mediated inhibition of ADP/ATP exchange can be separated from Bax-stimulated formation of nonspecific pores by ANT. Chemotherapy-induced apoptosis caused an inhibition of ANT activity, which preceded the loss of the mitochondrial transmembrane potential and could be prevented by overexpression of Bcl-2. These data are compatible with a model of mitochondrial apoptosis regulation in which ANT interacts with either Bax or Bcl-2, which both influence ANT function in opposing manners. Bcl-2 would maintain the translocase activity at high levels, whereas Bax would inhibit the translocase function of ANT.
authors.affiliation: CNRS-UMR6022, Université de Technologie de Compiègne, 60205 Compiègne, France.
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Belzacq
authors.forename: Helena L A
authors.initials: HL
authors.lastname: Vieira
authors.forename: Florence
authors.initials: F
authors.lastname: Verrier
authors.forename: Grégoire
authors.initials: G
authors.lastname: Vandecasteele
authors.forename: Isabelle
authors.initials: I
authors.lastname: Cohen
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Prévost
authors.forename: Eric
authors.initials: E
authors.lastname: Larquet
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Pariselli
authors.forename: Patrice X
authors.initials: PX
authors.lastname: Petit
authors.forename: Axel
authors.initials: A
authors.lastname: Kahn
authors.forename: Rosario
authors.initials: R
authors.lastname: Rizzuto
authors.forename: Catherine
authors.initials: C
authors.lastname: Brenner
authors.forename: Guido
authors.initials: G
authors.lastname: Kroemer
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D006367:HeLa Cells; D006801:Humans; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism; D000226:Mitochondrial ADP, ATP Translocases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D014162:Transfection; D051028:bcl-2-Associated X Protein
chemical_list: C494826:BAX protein, human; C494828:Bax protein, rat; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000226:Mitochondrial ADP, ATP Translocases