Dr. Dejean earned his Ph.D. in Biochemistry and Cell Biology from the University of
Bordeaux 2. He has done post-doctoral research at the University of Barcelona and
worked as a research assistant and faculty member at New York University. He joined
the chemistry faculty at Fresno State in 2011.
Areas of Specialty Mitochondria are organelles involved in both life and death processes within all eukaryotic
cells. These organelles release pro-death mediators during early apoptosis; and this
release represents the commitment step of programmed cell death. The Bcl-2 family
of proteins is a key regulator of the mitochondrial response to apoptotic signals.
This family contains both pro- (Bax and Bak) and anti- (Bcl-2 and Bcl-xL) apoptotic
members. All these proteins eventually localize to mitochondria and finely regulate
the release of apoptotic mediators. The focus of my research is to understand the
mechanisms that underlie and control this release of mitochondrial proteins during
both physiological and pathophysiological conditions.
The upregulation of the anti-apoptotic Bcl-2 and/or Bcl-xL leads to a resistance to
apoptosis associated with tumor formation. Mimicking this status through Bcl-2 or
Bcl-xL overexpression induces the inhibition of mitochondrial permeabilization. Interestingly
however, Bcl-2 or Bcl-xL overexpression leads to an increase of Bax in the mitochondrial
outer membrane. Thus, Bcl-2 and Bcl-xL seem to antagonize Bax in healthy cells, but
these proteins may become “partners in crime” to eliminate tumors by allowing the
accumulation of Bax at the mitochondria. The objectives of our laboratory are then
to investigate the molecular mechanisms through which Bcl-2 and Bcl-xL capture Bax
at the mitochondria and how this phenomenon could allow to specifically kill cancer
cells. We will more particularly study the effects of Bcl-2/xL expression levels on
mitochondrial Bax interactome. Finally, the influence of Bcl-2/xL binding capacity
to Bax on cell bioenergetics will also be investigated as metabolic alterations are
a common feature in several types of tumors.