Abstract: Autophagy is a ubiquitous process of intracellular self-degradation, which is well conserved from yeasts to mammals and strictly regulated by upstream signaling pathways such as energy and nutrient. Studies in mammals have shown that autophagy has a close relationship with lipid metabolism. Autophagy could be induced by high level of lipid in dietary, while knockout of some autophagy related genes (Atg) can block lipid degradation in liver and cause accumulation of lipid droplets. Studies in insects also imply that autophagy is important for lipid degradation. Up to now, there are still many questions remaining unanswered on the autophagy-mediated lipid metabolism. Besides a few identified ATG proteins, whether some other ATG proteins are also involved in lipid metabolism has not been reported. The molecular mechanism of lipid metabolism regulated by identified ATG proteins is unclear. What enzymes in the lysosome participate in autophagy-mediated lipid metabolism has not been confirmed. In addition, ATG proteins differently participate in lipid droplet formation and lipid degradation in fungi and higher animals, but the mechanism is unknown. The evolutionary status of insects is between fungi and higher animals, the studies of autophagy-mediated lipid metabolism in insects will be helpful for uncovering the mechanisms underlying obesity and hyperlipidemia in higher animals, and also have great significance in the researches with the metabolism and development in the fat body of insects as the regulating targets. So in this article we summarized the progress of autophagy-mediated lipid metabolism mainly in mammals, and introduced the research methods and detection techniques of lipid metabolism to enlighten the related studies in insects and other organisms.

Key words: Autophagy, autophagosome, autophagy related protein (ATG), fat body, lipid metabolism