Tetraspanins are ubiquitously expressed at the plasma membrane of eukaryotic cells and are associated to membrane remodeling through the formation of a dynamic network of protein-protein-lipid interactions. As membrane organizers, they interact dynamically with other membrane proteins such as members of the Ig superfamily (EWI) or integrins. Tetraspanins are key proteins during infection and cancer.
We explored the role of CD9 and CD81 tetraspanins recruitment at HIV-1 budding sites using a correlative AFM / superresolution microscopy (PALM/STORM) setup developed in collaboration with MN. We were able to correlate membrane topography and tetraspanin distribution in intact cells with a 30 nm lateral resolution for both techniques (Figure 2). We demonstrated that these proteins are concentrated at the tip of nascent viral particles where membranes are highly-curved, suggesting that they could play a role of curvature scaffolds, and explained CD9 and CD81 depletion upon Gag expression.We also investigated the influence of the tetraspanin CD82 on membrane properties (partition, dynamics, tension) in the context of cancer metastasis. We demonstrated that CD82 influences expression and dynamics of membrane components in breast immortalized cells and cell mechanics by tuning membrane tension (measured by pulling tubes with an AFM tip). Our recent results suggest that CD82 may behave as a metastasis suppressor and regulate many cell signaling functions by controlling both membrane tension and cell mechanics by acting on caveolae. We also analyzed cell mechanics during colon cancer progression in tissues of patients with a mutated KRas gene in their tumor.
PI : Pierre-Emmanuel MILHIET. People involved : Christine BENISTANT, Christine DOUCET, Luca COSTA
Collaborator :
Team Integrative Biophysics of Membranes 