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Mitochondrial proteomic approach reveals galectin-7 as a novel BCL-2 binding protein in human cells
Author(s) -
Christelle Villeneuve,
Laurent Baricault,
Ludovic Canelle,
Nadia Barboule,
Carine Racca,
Bernard Monsarrat,
Thierry Magnaldo,
Florence Larminat
Publication year - 2011
Publication title -
molecular biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.463
H-Index - 225
eISSN - 1939-4586
pISSN - 1059-1524
DOI - 10.1091/mbc.e10-06-0534
Subject(s) - biology , mitochondrion , microbiology and biotechnology , apoptosis , endoplasmic reticulum , genetics
Although the anti-apoptotic activity of Bcl-2 has been extensively studied, its mode of action remains incompletely understood. Deciphering the network of Bcl-2 interacting factors is necessary to better understand the key function of Bcl-2 in apoptosis initiation. To identify novel Bcl-2 mitochondrial partners, we have combined a Bcl-2 immunocapture with a mass spectrometry analysis using highly pure mitochondrial fractions isolated from human cancer cells. We identified at high confidence 127 potential Bcl-2–interacting proteins. Gene ontology mining reveals enrichment for mitochondrial proteins, endoplasmic reticulum–associated proteins, and cytoskeleton-associated proteins. Importantly, we report the identification of galectin-7 (Gal7), a member of a family of β-galactoside–binding lectins that was already known to exhibit a pro-apoptotic function, as a new mitochondrial Bcl-2 interacting partner. Our data further show that endogenous Bcl-2 coimmunoprecipitates with Gal7 and that recombinant Gal7 directly interacts with recombinant Bcl-2. A fraction of Gal7 is constitutively localized at mitochondria in a Bcl-2–dependent manner and sensitizes the mitochondria to the apoptotic signal. In addition, we show that the Bcl-2/Gal7 interaction is abolished following genotoxic stress. Taken together, our findings suggest that the binding of Gal7 to Bcl-2 may constitute a new target for enhancing the intrinsic apoptosis pathway.

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