Lipids@Wayne Seminar: Jeeyun Chung Ph.D. Protein machinery of lipid droplet formation
This event is in the past.
Please attend our upcoming Lipids@Wayne seminar featuring Jeeyun Chung Ph.D. All are welcome. Pizza will be served.
Speaker: Jeeyun Chung Ph.D., Postdoctoral Fellow, Harvard Medical School
Title: Protein machinery of lipid droplet formation
Location: 1167 Biological Sciences
Date and Time: 4 pm on Wednesday, Februrary 5, 2020
Lipid droplets (LDs) are intracellular organelles providing cells with a reservoir of fat molecules, such as triacylglycerol and sterol ester. When needed, these molecules can be mobilized as building blocks for membranes or substrates for energy metabolism. Despite the central role of LDs in lipid metabolism, it is poorly understood how LDs are generated. An improvement in resolution/volume for focused ion beam-scanning electron microscopy (FIB-SEM) enabled us to visualize finer details of subcellular architecture and provided us a better understanding of a process of LD formation. Analyses of these data revealed that LDs dynamically contact with other organelles, particularly with the ER, suggesting involvement of ER proteins in LD formation. Supporting this, the ER membrane protein seipin was shown to localize to ER-LD contacts soon after LDs form, but what determines the sites of initial LD biogenesis in the ER is unknown. This presentation will focus on another ER membrane protein, lipid droplet assembly factor 1 (LDAF1), that we recently identified by seipin immunoprecipitation-coupled mass spectrometry. With multidiscipline approaches including advanced imaging, cryo-electron microscopy, and biochemistry, we found that LDAF1 and seipin form ~600 kDa oligomeric complex at the ER and play a role in LD formation. Based on our results, we propose that the LDAF1-seipin complex is the core protein machinery that facilitates LD biogenesis and determines the sites of their formation in the ER.