Offer: Funded one-year Post-doctorate
Laboratories: Sorbonne Université, Paris, France (Laboratoire des BioMolécules and Laboratoire de Réactivité de Surface)
Cell penetrating peptides (CPPs) are a family of peptides, which present the ability of crossing the cell membrane. When bound to another molecule, they can be used as vectors to deliver molecules inside the cell. This ability has led to many applications in different fields such as research, imaging or medicine. The molecular mechanism of the direct crossing of the cell plasma membrane by CPPs, the direct translocation, remains poorly understood. Understanding it is crucial to optimize the use of CPPs and gain a better control on the final location of these CPPs and their cargos inside the cell. The objective of this project is deciphering the mechanism of the direct translocation at molecular level.
Understanding the direct translocation requires to identify the partners of the CPP during the different steps of its translocation: adhesion on the membrane, insertion, crossing. Many molecules are likely to be involved: lipids, carbohydrates and membrane proteins. Another crucial question is to determine the translocation driving force: the transmembrane potential naturally present on cells and the electric fields created by the positively charged CPPs are likely to be involved.
To address these questions, we will design microfluidic devices enabling to study the translocation of CPPs through model membrane while controlling the electrical parameters of the bilayers. The model membrane will be a Droplet Interface Bilayers (DIB), which is spontaneously formed at the interface between two micrometric aqueous droplets bathed in oil containing lipids. This choice is guided by the possibility to form asymmetric bilayers and to control the aqueous environments on the two sides of the bilayer. By introducing the CPPs in one of the aqueous droplets, it is thus possible to choose different partners that CPPs can meet at each stage of the translocation which is detected by fluorescence microscopy. We will develop a new high throughput multiple DIBs formation method, based on the use of microfluidic devices, which will allow us to test numerous potential CPP partners by generating simultaneously a set of similar droplet pairs and thus significantly improve the speed and reproducibility of the experiments. It will enable to go towards more biomimetic systems for example by testing the role of minority lipids such as PIP2. In an advanced stage of the project, we will add two electrodes underneath the droplets. The new microfluidic chip with integrated microelectrodes will be used to study the effect of transmembrane potential on the translocation efficiency, to evidence possible transient change in the membrane electric properties due to rearrangement of the system during the translocation, and finally to detect a possible perturbation of the potential by the layer of charged CPPs that will form on the DIBs. All these measurements will be performed on different CPPs and various lipid environments.Selection process
- First contact by email to email@example.com with CV and motivation letter
- Meeting in person in Paris or online interviewsOffer Requirements
Physics: PhD or equivalent
Biological sciences: PhD or equivalentSkills/Qualifications
Skills of the candidate: