C1_Apoptosis
Investigation and Analysis of Pro- and Antiapoptotic Pathways in Hepatocytes
Institute of Molecular Medicine and Cell Research (University of Freiburg)
Prof. Dr. Christoph Borner (PL), Dr. Robert Pick (PhD), Karine Sa Ferreira (PhD student), Angelika Haber (TA)
Life Imaging Center (University of Freiburg)
Dr. Roland Nitschke
Department of Bioinformatics (University of Würzburg)
Prof. Dr. Thomas Dandekar (PL), Nicole Philippi (PhD student)
MPI for Dynamics of Complex Technical Systems (Magdeburg)
Prof. Dr. Ernst Dieter Gilles (PL), Dipl.-Biol. Markus Koschorreck (PhD student)
Institute for System Dynamics (University of Stuttgart)
Prof. Dr. Oliver Sawodny (PL), Prof. Dr.-Ing. Thomas Sauter (PL), Dipl.-Biol. Markus Koschorreck (PhD student),
Rebekka Schlatter (PhD student)
Center for Data Analysis and Modelling (University of Freiburg)
Prof. Dr. Jens Timmer (PL), Dipl.-Phys. Clemens Kreutz (PhD student)
Project summary:
The Fas/CD95 ligand of the TNF superfamily plays a crucial role in both the apoptotic and the damage-induced regenerative response of hepatocytes. While it is known that after in vivo injection of agonistic anti-Fas antibodies, hepatocytes undergo fulminant apoptosis, dependent on the BH3-only protein Bid and cytochrome c-mediated caspase-3 activation, it has not yet been defined if the same pathway is used ex vivo , i.e when hepatocytes are isolated and grown on collagen or Matrigel surfaces. Moreover, it has remained enigmatic how hepatocytes re-enter the cell cycle after damage and how FasL contributes to this switch. Our project uses genetic, bioinformatical, biochemical and cellular techniques to molecularly define the apoptotic and proliferative pathways of isolated hepatocytes in response to FasL in vitro . For the proliferative switch, FasL-stimulated hepatocytes will be co-treated with mitogens such as EGF, HGF-1, insulin, IGF-1 or IL-6 to understand their role in blocking apoptosis, but favouring mitogenic signaling by FasL. Particular attention will be paid to interactome analysis and enhanced expression/action of the apoptosis inhibitors FLIP, CARP, XIAP and anti-apoptotic members of the Bcl-2 family as well as to the possibility that receptors for HGF, EGF, etc. may interact with Fas and thereby deviate the apoptotic signal towards proliferation. If ever possible, changes in expression/activity of the various signalling molecules will be monitored on the single cell level (using FRET or GFP-fusion constructs) and all the measured data will be used to develop mathematical models for apoptosis and mitogenic signalling and signaling components. Regulatory proteins, adaptors and receptors of the CD95L/TNF pathway will also be analyzed in detail regarding sequence, structure and interaction switches (e.g. death domains ) and resulting network logic The integration of the different models and perspectives will then allow the HepatoSys consortium to develop quantitative systems biology simulations on the hepatic cell decision of apoptosis versus proliferation.
Former co-workers: Dorothée Walter, Armin Robubi