Protein-Protein Interactions in Perilpin 5

Many metabolic diseases contribute to a major part of the health crisis in the US. Type II diabetes mellitus and non-alcoholic fatty liver disease are two examples of metabolic diseases that are contributing to the current health crisis. Key to understanding these diseases and their progression is an understanding of neutral lipid metabolism. Perilipins are a class of five conserved proteins that are key regulators of lipid metabolism and are potentially involved in lipid trafficking within cells. The most recently discovered member of the family is perilipin 5, which is expressed most strongly in tissues that are highly oxidative such as heart, oxidative muscle, and fasting liver. Perilipin 5 is predominantly located on the surface of lipid storage droplets, but has also been found in the cytoplasm, nucleus, the endoplasmic reticulum, and mitochondria. We hypothesized that perilipin 5 moves between these cellular pools via interactions with other proteins. Furthermore, we hypothesized that interactions with Rabs were necessary for this trafficking to occur. CHO cells expressing perilipin 5 and Rab18 were assayed using western blotting and were found to have interactions through the appearance of protein bands for both perilipin 5 and Rab18. Immunoprecipitations were used to assay for interactions between perilipin 5, Rab18, and Rab32. Immunofluorescence immunochemistry was used to determine cellular pools of interactions between perilipin 5 and Rabs and has shown perilipin 5 and Rab18 to be colocalized in certain cellular pools. Collectively these data provide a more detailed picture of perilipin 5 in the cell