We are working on the mechanisms of fat transport, storage and consumption in adipocytes, the main fat storing cells of our bodies. Specifically, we aim at elucidating the molecular mechanisms that underlie the size regulation of specialized fat storing organelles called lipid droplets (LDs). The scheme below shows a differentiating adipocyte with growing LDs (in yellow) that eventually fill up the entire cytoplasm of the cell. We want to understand in molecular terms how in adipocytes LDs can grow so big.
Functional coupling of the ER and LDs in adipocytes
The endoplasmic reticulum (ER, here in green) likely plays a major role in LD generation and expansion. Electron microscopy studies show a tight association between LDs and the ER and physical coupling between the organelles is probably necessary for LD expansion. In a recent paper we made the unexpected discovery that proteins that are involved in shaping the ER also play a role in LD size regulation. We are currently investigating how the ER is functionally coupled to LDs. Our preliminary data indicate that in adipocytes the ER and the LDs are linked by a protein or protein complex. Major focus of our research is to identify this ER-LD link complex (depicted as red spheres in the blow up above) and study its functional role in adipocyte biology.