Regensburg 2010 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 31: Posters: Membranes and Vesicles

BP 31.16: Poster

Donnerstag, 25. März 2010, 17:15–20:00, Poster B1

Observing the growth of lipid droplets in vivo and in vitro — •Mária Hanulová and Matthias Weiss — Cellular Biophysics Group, DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg

Lipid droplets (LD) are fat deposits of cells. In simple terms, they are balls of triglycerides (TG) and cholesteryl esters (CE) surrounded by a phospholipid monolayer into which proteins are embedded. Lipid droplets store excess fatty acids, release them in case of need, and are linked to many metabolic diseases. As of yet, the biogenesis and growth of LDs is poorly understood. According to the most popular model, TG and CE are synthesized at the endoplasmic reticulum (ER) and self-assemble as a globule between the leaflets of the ER membrane. Most likely, LDs then pinch off and carry away lipids from the ER membrane as a protecting monolayer. The growth of LDs has been hypothesized to rely on two (not mutually exclusive) mechanisms: (i) fusion with other LDs, or (ii) acquisition of newly synthesized lipids. To approach this problem, we observed the growth of lipid droplets in living HeLa cells by time-resolved confocal microscopy. Additionally, we used time-resolved fluorescence correlation spectroscopy in vitro to validate the physical possibility of fusion of lipid droplets. These experimental results are in favorable agreement with large-scale simulations of ours.