Date : 18/10/2011

Internship proposal for : Master 2

Laboratory
Subcellular structure and cellular dynamic - Compartimentation et dynamique cellulaires
UMR 144 CNRS-Institut Curie
26 rue d'Ulm 75248 Paris cedex 05
Website
Main discipline : Cell Biology
Lab director : Bruno Goud

Mentor
Jean-Baptiste Manneville
email : This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
tel +33 1 56 24 65 64

Subjects
1.: intracellular transport
2.: membrane mechanics
3.: cytoskeleton

Tools and methodologies
1.: optical tweezers
2.: confocal microscopy
3.: microrheology

Summary of lab's interests

The number of studies focusing on the mechanics of the plasma membrane of eukaryotic cells has grown steadily in the last twenty years. In contrast, the mechanics of intracellular membranes is still poorly understood, although these membranes clearly play a key role in numerous cellular functions, for instance during intracellular transport. Membrane transport within the cell is based on the formation of tubulo-vesicular intermediates that shuttle along the cytoskeleton between intracellular compartments. In vitro experiments have highlighted the roles of membrane curvature and membrane tension in the budding of transport intermediates [1,2]. And a recent study in the lab has shown that the actin cytoskeleton controls the fission of intermediates from the Golgi apparatus [3]. To better characterize the physics of intracellular membranes, we have developed a new technique based on the micromanipulation by an optical tweezers of micron-sized beads internalized by mammalian cells. The technique allows to apply and measure a mechanical constraint on a given intracellular compartment and to visualize simultaneously with fast confocal microscopy the compartment of interest labelled by specific fluorescent proteins. Until now, we have focused on the Golgi apparatus. We have shown that Golgi membranes are deformed upon the application of the mechanical constraint and that the actin cytoskeleton strongly contributes to the rigidity of the Golgi apparatus. In agreement with the in vitro experiments [1], applying a mechanical constraint inhibits the formation of transport vesicles from the Golgi apparatus [4]. References: [1] J.-B. Manneville et al. Proc Natl Acad Sci U S A 105 16946-16951 (2010) [2] E. Ambroggio et al. EMBO J 29 292-303 (2010) [3] S. Miserey-Lenkei et al. Nature Cell Biol 12 645-54 (2010) [4] D. Guet et al. in preparation

Summary of project

The M2 project is a follow-up to this work. The candidate will continue the study on the Golgi apparatus in order to 1) measure the mechanical properties of Golgi membranes (bending rigidity, visco-elasticity); 2) better understand the respective roles of the membranes, the actin cytoskeleton and the Golgi matrix; and 3) determine whether the decrease in the formation of transport vesicles observed upon the application of a mechanical constraint is due to a defect in membrane budding or in fission of the vesicles.