The major goal of this project was to unravel how proteins interact with the surface of lipid droplets. Lipid droplets are fat particles that are crucial for supplying and regulating energy within the cell and are involved in a whole host of other cellular processes. They are similar in structure to the more well-known lipoproteins that circulate in the blood stream (e.g. LDL and HDL). This research focuses on how proteins, initially formed inside the cell, are targeted to and bind to the surface of these lipid droplets, where they regulate droplet structure and function. While much is known about how proteins bind to the lipid membranes that compartmentalize complex cells, very little is known for lipid droplets. Using model proteins, this research determined some of the complex interactions responsible for the binding of lipid droplet proteins. Graduate, undergraduate, and high school students worked together in a highly interdisciplinary environment. Additionally, this work resulted in meaningful educational experiences for low socioeconomic and minority background students, increasing STEM degrees among diverse students.

 This award resulted in four publications to date, one dissertation and contributed to the work of two additional dissertations. One of our manuscripts on the protein named perilipin 3 received an editor’s choice designation. This award also led to several invited talks (one keynote lecture) at international meetings by the PI, and multiple poster and oral presentations by the graduate and undergraduate students.

 Major Outcomes: A common theme in proteins that bind to oil (think olive oil e.g.) is that they contain a structure called an “amphipathic α-helix bundle” domain. This protein structure is hydrophobic on the inside, and hydrophilic on the outside and can open-up, upon interacting with an interface. In our work we showed that this “unfolding” to expose internal hydrophobic structures is critical for the proper binding and insertion of apolipoproteins and lipid droplet binding proteins into a lipid coated oil droplet. Additionally, we showed that the human lipid droplet binding protein, perilipin 3, inserts better into phospholipid monolayers (a single molecule thick) with more unsaturated lipids coating the oil droplet. Lipid saturation determines, among other things, if an oil or lipid is fluid” at room temperature. Olive oil is unsaturated and fluid at room temperature, and palm oil is more saturated and solid at room temperature. Our work clearly underscores the importance of investigating the different domains of lipid droplet binding proteins, as well as modulating the lipid composition of the lipid droplet outer monolayer. We were the first to publish the effect of lipid (un)saturation on the binding of these types of proteins.

 Broader Impact: Six graduate and 16 (all female) undergraduate students contributed to this project. One graduate student, whose PhD dissertation detailed the results of lipid saturation on protein binding, initiated several external collaborations with Industry, and Government (NASA/Airforce). They now work at Cleveland Diagnostics, a company that offers novel, more accurate testing for early detection of cancer and risk of high-grade disease. Another graduate student who assisted in protein construct generation is now a postdoc at Harvard Medical School where they study the role of lipids in Alzheimer’s disease. All graduate and undergraduate students supported by the grant were exposed to highly interdisciplinary research and had the opportunity to present their results at (inter)national conferences. Several of our undergraduates won prizes for oral and poster presentations of their research, and after graduation move on to challenging professional programs such as veterinary and medical school. Two recently graduated from professional school (PharmD and VetD programs) and have started their residencies. The PI continued his extensive science outreach both at the university and community level.

Last Modified: 12/17/2024
Modified by: Edgar E Kooijman