Invitée équipe R. Reguera: Wioleta Dudka, postdoc dans le groupe de Julia Mahamid, EMBL Heidelberg – “Physiological ordered packing of cholesterol esters in lipid droplets in mammalian tissue described by Cryo Serial Lift-Out”

Résumé

As organelles at the center of intracellular lipid fluxes, Lipid Droplets (LDs) serve versatile functions including cellular lipids and proteins handling and as a hub of several key cell signaling pathways. However, undoubtedly the major function of LDs is a storage of lipids, in the form of mixture of triacylglycerols (TAG) and cholesterol esters (CE) constituting the core of LDs, surrounded by the monolayer of phospholipids. Until recently, LDs were considered unstructured, however developments in cellular cryo-electron microcopy enabled to study organization of LDs in close-to-physiological conditions and revealed the presence of higher order arrangements of concentric rings surrounding an amorphous core inside LDs in specific cellular scenarios and organisms. Using a combination of cellular cryo-EM, polarization microscopy, spatial metabolomics, histology and cryo-serial Lift-Out of tissue, we found that hormone producing tissue in mammals, like adrenal glands, physiologically store cholesterol in LDs in the for of liquid-crystalline arrangements.