Funding of a PhD M/F in biological and medical sciences

The work will be split between the IBGC CNRS UMR5095 in Bordeaux and the Inserm U1034 in Pessac.
The candidate should be familiar with the following techniques: Cell biology: cell culture, protein overexpression and silencing by lentiviral transduction, classical transfection, light and fluorescence microscopy. Protein biochemistry: immunoprecipitation, electrophoresis under denaturing or native conditions, western blot, ELISA. Training in animal experimentation will be a plus.

Ageing is a normal process that affects all cell types, tissues and organs. It is also associated with disease, and understanding the mechanisms that regulate ageing is a major public health challenge. Conversely, cancer cells are immortal, and an attractive therapeutic option would be to accelerate their ageing.
We are interested in protein deamidation, which is the slow conversion of asparagine residues to aspartate/Isoaspartate residues within proteins. Our object of study is the Bcl-xL oncogene. We have found that the deamidation state of Bcl-xL is a marker of age in platelets. These small, anucleated blood cells play an important role in coagulation. We observed that Bcl-xL is double-deamidated in aged platelets, and not deamidated in neosynthesised platelets. Platelets are a unique model in terms of regulating their lifespan since it is only controlled by Bcl-xL for their survival and Bak for their death. Platelets survive as long as Bak is kept inactive by Bcl-xL. The mechanism responsible for the dissociation of Bak and Bcl-xL remains unknown to date. Our finding that deamidated Bcl-xL accumulates in aged platelets is central to the hypothesis that will be tested in this thesis: whether deamidation is a simple marker of age, or whether it conditions platelet death.
Our goal is to determine the mechanism of platelet end of life. We propose to test whether Bcl-xL deamidation is merely a modification that accumulates with age, or whether it is responsible for triggering platelet apoptosis, by causing the dissociation of pro-apoptotic proteins such as Bak. To determine the functional consequences of Bcl-xL deamidation, we will use cultured cells to study the role of deamidation at Asp, and in vitro approaches to study the role of deamidation at Iso-Asp in molecular interactions with Bak.
To determine whether deamidation causes platelet cell death, we will work in the mouse model to perform immunoprecipitations and determine whether deamidation of Bcl-xL alters its ability to interact with Bak. We will also measure how deamidation alters the lifespan of platelets in mice.
Finally, we will ask whether the deamidation state of Bcl-xL can be used as a marker to screen for new molecules that would extend the shelf life of platelet concentrate units.