Recruitment of Peroxin14 to lipid droplets affects triglyceride storage in Drosophila

The activity of multiple organelles must be coordinated to ensure cellular lipid homeostasis. This includes the peroxisomes which metabolise certain lipids and lipid droplets which act as neutral lipid storage centres. Direct organellar contact between peroxisomes and lipid droplets has been observed, and interaction between proteins associated with the membranes of these organelles has been shown, but the functional role of these interactions is not clear. In Drosophila cells, we identified a novel localization of a subset of three transmembrane Peroxin proteins (Peroxin3, Peroxin13, and Peroxin14), normally required for peroxisome biogenesis, to newly formed lipid droplets. This event was not linked to significant changes in peroxisome size or number, nor was recruitment of other Peroxin proteins or mature peroxisomes observed. The presence of these Peroxin proteins at lipid droplets influences their function as changes in the relative levels of Peroxin14 associated with the lipid droplet surface directly affected the presence of regulatory perilipin and lipases with corresponding effects on triglyceride storage. Summary statementInteractions between peroxisomes and lipid droplets is thought to help coordinate management of cellular lipids. Peroxin proteins are required for peroxisome biogenesis. A spectrum of effects on triacylglyceride storage was seen when each of the 12 conserved Peroxins are knocked down in the Drosophila fat body with Peroxin14 knockdown having the largest effect. When Drosophila S2 cells were cultured in excess oleic acid, Peroxin3, Peroxin13, and Peroxin14, but not other Peroxins were localized to lipid droplets independently of other peroxisome markers. The presence of Peroxin14 at the lipid droplet surface altered recruitment of perilipin and lipase proteins.