Les séminaires ont lieu sur le Campus Montpellier SupAgro/INRAE
de La Gaillarde (2, place P. Viala Montpellier)

Jeudi 16 février

à 14h Amphi 2 (Bât.2bis)

Yohann BOUTTE

(LBM-Bordeaux)

The two-side of a membrane or how lipid-lipid interactions shape membrane trafficking and dynamics

The lipid composition of biological membranes acts as a landmark to define their identity and specify subcellular functions. Some membrane lipids, usually anionic, are able to recruit key elements of membrane trafficking or to modulate the packing of transmembrane helices through their fatty acyl-chains structure. However, biological membranes contain hundreds of lipid species and very little is known on how different lipids interact between each other and how the lipid composition is regulated in different membrane compartments. We focus on two different membranes, the plasma membrane (PM) and the post-Golgi compartment called trans-Golgi Network (TGN) which is a central trafficking hub in the cell acting in protein sorting. The PM and the TGN are not disconnected as the TGN hosts both secretion and the early endocytic materials. Thus, we try to decipher the mechanisms that regulate the lipid composition and the lipid homeostatic interactions both at PM and the TGN. We have previously shown that the acyl-chain length of α-hydroxylated fatty acids, a specific signature of sphingolipids, is crucial to the polar secretory sorting of the auxin efflux carrier PIN2 at a specific sub-domain of TGN. However, the underlying mechanism remained to be characterized. In this work, we show that the acyl-chain of sphingolipids acts on the homeostasis of the anionic phospholipid phosphatidylinositol-4-phosphate (PI4P). Using multiple approaches, we found that sphingolipids mediate the consumption of PI4P through phosphoinositide-specific phospholipase C (PI-PLC) and this process impacts PIN2 sorting at the TGN and its trafficking to the apical polar domain of the plasma membrane. Complementarily to what we found at the TGN, we will share recent data we obtained on the function of the acyl-chain length of fatty acids on the lateral mobility of synthetic markers either located at the outer or inner leaflet of the PM as well as endogenous proteins either associated with or integral to the PM. We additionally surveyed the functional relevance of the length of the acyl-chain of fatty acids in lipid-lipid homeostatic interactions across leaflets of the PM. Together, our results will bring forward an unexplored side of the lipid-mediated membrane trafficking and dynamics as well as shed the light on lipid-lipid interactions and homeostasis.