Cluster of Excellence –
University of Freiburg

Rebuilding mitochondrial apoptosis

Prof. Dr. Georg Häcker (Department Microbiology and Hygiene, University Medical Centre Freiburg)

Mitochondrial apoptosis is responsible for most forms of apoptosis in vivo. During mitochondrial apoptosis, pro-apoptotic (Bcl-2-family) BH3-only proteins (such as Bim and tBid) initiate the activation of pro-apoptotic Bax/Bak, while anti-apoptotic Bcl-2-proteins inhibit this. The presence of over ten Bcl-2-family members, the lack of quantitative information of inhibition/ activation requirements and the unknown status of activity and complex formation between Bcl-2- proteins in cell lines impedes understanding mitochondrial apoptosis by analytical approaches. The goal of this project is the synthesis of mitochondrial apoptosis from various components in cell-free systems and in intact cells. We will use experimental levels of increasing complexity, starting from liposomes and recombinant proteins over isolated yeast and mouse mitochondria to intact cells. By combining a number of in vitro approaches with techniques like high-resolution microscopy, we will endeavour to rebuild mitochondrial apoptosis from individual components in vitro and eventually in mammalian cells.

A fluorescent fusion protein (mCherryBax) is constitutively expressed in MEF cells. Upon tet-induced up-regulation of Bim, Bax is recruited to mitochondria.