Bcl-2 and Bax modulate adenine nucleotide translocase activity

• Published in: Cancer research (Chicago, Ill.) Vol. 63; no. 2; pp. 541 - 546
• Main Authors: BELZACQ, Anne-Sophie, VIEIRA, Helena L. A, RIZZUTO, Rosario, BRENNER, Catherine, KROEMER, Guido, VERRIER, Florence, VANDECASTEELE, Grégoire, COHEN, Isabelle, PREVOST, Marie-Christine, LARQUET, Eric, PARISELLI, Fabrizio, PETIT, Patrice X, KAHN, Axel
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 15.01.2003
• Subjects: Adenosine Diphosphate - metabolism; Adenosine Triphosphate - metabolism; Ageing, cell death; Animals; bcl-2-Associated X Protein; Biochemistry; Biochemistry, Molecular Biology; Biological and medical sciences; Cell physiology; Fundamental and applied biological sciences. Psychology; HeLa Cells; Humans; Life Sciences; Mitochondria - enzymology; Mitochondria - metabolism; Mitochondrial ADP, ATP Translocases - metabolism; Molecular and cellular biology; Proto-Oncogene Proteins - metabolism; Proto-Oncogene Proteins - physiology; Proto-Oncogene Proteins c-bcl-2 - genetics; Proto-Oncogene Proteins c-bcl-2 - metabolism; Proto-Oncogene Proteins c-bcl-2 - physiology; Rats; Transfection; Human; Mitochondria; Enzymatic activity; Enzyme; Cell death; C-Onc gene; Established cell line; Molecular interaction; Mechanism of action; In vitro; Protooncogene; Apoptosis
• ISSN: 0008-5472; 1538-7445

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.