Monoacylglycerol disrupts Golgi structure and perilipin 2 association with lipid droplets

Abstract

The two major products of intestinal triacylglycerol digestion and lipoprotein lipolysis are monoacylglycerols (MAG) and fatty acids. In the gut, these products are taken up by enterocytes and packaged into perilipin-coated cytosolic lipid droplets and then secreted as chylomicrons. We observed that fat feeding or intragastric administration of triacylglycerol oil caused the enterocyte Golgi to fragment into submicron puncta dispersed throughout the cytosol. Further, this apparent Golgi dispersion was also observed in cultured fibroblasts after treatment with fat (cream) and pancreatic lipase, but not when treated with deactivated lipase. We therefore hypothesized that a hydrolytic fat product, specifically monoacylglycerols, fatty acids or a combination of these molecules can trigger Golgi fragmentation. Disruption of coatomer function is known to cause Golgi to fuse with the ER, and blocks perilipin 2 delivery to lipid droplets. Thus, we assessed the effects of MAG on coatomer distribution, Golgi structure and perilipin 2 localization. We found that MAG, but not fatty acids, dispersed coatomer from the Golgi, fragmented the Golgi and caused perilipin 2 to accumulate on cellular membranes. Thus, our findings suggest that monoacylglycerol production during digestion disperses the Golgi, possibly by altering coatomer function, which may regulate metabolite transport between the ER and Golgi.