Lipid droplets (LDs) are ubiquitous organelles in eukaryotic cells that organize and store cellular lipids, including triacylglycerols (TGs), which provide stores of energy and sources of membrane lipids. Despite recent advances in understanding LD biology in cellular physiology and disease, most fundamental key questions about LDs remain unanswered. In this proposal, we focus on the most basic question of determining the mechanisms underlying LD formation. To do so, Aims 1 and 2 will employ a novel system we developed, in which LD formation is induced on a null background in mammalian cells. We accomplish this by inducing acyl CoA: diacylglycerol acyltransferase (DGAT) 1 or DGAT2, which catalyze TG synthesis and lie just upstream to the process of LD formation. By inducing LD formation in cels, we will address key questions: How is TG synthesis coordinated with newly forming LDs? Where in the cell do LDs form? How do monolayer-bound LDs form from bilayer membranes? Specifically, Aim 1 focuses on determining the localization and activity of DGAT enzymes before, during, and at later stages of LD formation.
Aim 2 focuses on determining where LD formation occurs in the cell, how LD formation relates to membrane topology, tubular (or curved) ER, and how TGs in the ER are organized during LD formation.
The final aim focuses on our findings that specific proteins, such as the hepatitis C Core protein, are apparently targeted to newly forming LDs.
Aim 3 therefore will elucidate the mechanism that underlies the targeting of Core to LDs and will identify other endogenous cellular proteins that gain access to LDs through this mechanism. Our studies will provide fundamental knowledge about LDs and cellular lipid metabolism. Additionally, a better understanding of LD formation may have therapeutic implications for diseases of LD excess, such as obesity, diabetes, and atherosclerosis, and may have practical applications in engineering plants and microorganisms for increased oil production.
Metabolic diseases of fat excess, such as obesity, type 2 diabetes, and atherosclerosis, are hugely prevalent disorders. The excess fat in these disorders is stored in cells in fat droplets or lipid droplets. Remarkably little is known about this aspect of cell biology. Our studies are focused on understanding the basic biology that underlies how fat droplets are formed in cells. Our work will lead to a greater understanding of diseases of fat excess and may lead to new therapies.
|Gluchowski, Nina L; Chitraju, Chandramohan; Picoraro, Joseph A et al. (2017) Identification and characterization of a novel DGAT1 missense mutation associated with congenital diarrhea. J Lipid Res 58:1230-1237|
|Kory, Nora; Farese Jr, Robert V; Walther, Tobias C (2016) Targeting Fat: Mechanisms of Protein Localization to Lipid Droplets. Trends Cell Biol 26:535-546|
|Kory, Nora; Thiam, Abdou-Rachid; Farese Jr, Robert V et al. (2015) Protein Crowding Is a Determinant of Lipid Droplet Protein Composition. Dev Cell 34:351-63|
|Fu, Dan; Yu, Yong; Folick, Andrew et al. (2014) In vivo metabolic fingerprinting of neutral lipids with hyperspectral stimulated Raman scattering microscopy. J Am Chem Soc 136:8820-8|
|Currie, Erin; Guo, Xiuling; Christiano, Romain et al. (2014) High confidence proteomic analysis of yeast LDs identifies additional droplet proteins and reveals connections to dolichol synthesis and sterol acetylation. J Lipid Res 55:1465-77|
|Wilfling, Florian; Thiam, Abdou Rachid; Olarte, Maria-Jesus et al. (2014) Arf1/COPI machinery acts directly on lipid droplets and enables their connection to the ER for protein targeting. Elife 3:e01607|
|Wilfling, Florian; Haas, Joel T; Walther, Tobias C et al. (2014) Lipid droplet biogenesis. Curr Opin Cell Biol 29:39-45|
|Thiam, Abdou Rachid; Farese Jr, Robert V; Walther, Tobias C (2013) The biophysics and cell biology of lipid droplets. Nat Rev Mol Cell Biol 14:775-86|
|Krahmer, Natalie; Farese Jr, Robert V; Walther, Tobias C (2013) Balancing the fat: lipid droplets and human disease. EMBO Mol Med 5:973-83|
|Klemm, Robin W; Norton, Justin P; Cole, Ronald A et al. (2013) A conserved role for atlastin GTPases in regulating lipid droplet size. Cell Rep 3:1465-75|
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