Lipid droplets (LDs) are conserved organelles for cellular fat storage. In C.elegans, numerous LDs can be found in intestinal cells, where fat is primarily stored. Proteomic studies have identified a large set of LD associated proteins. However, mechanisms governing the targeting and turnover of these proteins are largely unknown. Our lab has previously identified DGAT-2 as a LD associated protein in C.elegans. DGAT-2 is an acyl-coA:diacylglycerol acyltransferase that catalyzes the synthesis of triacylgclyerol, which is stored in LDs. DGAT-2 is localized to LDs when animals are actively feeding. However, DGAT-2 is undetectable in starved animals. In contrast, another LD associated protein, the short-chain dehydrogenase 3 (DHS-3), remains stable under the same condition. Our obe...[ Read more ]

Lipid droplets (LDs) are conserved organelles for cellular fat storage. In C.elegans, numerous LDs can be found in intestinal cells, where fat is primarily stored. Proteomic studies have identified a large set of LD associated proteins. However, mechanisms governing the targeting and turnover of these proteins are largely unknown. Our lab has previously identified DGAT-2 as a LD associated protein in C.elegans. DGAT-2 is an acyl-coA:diacylglycerol acyltransferase that catalyzes the synthesis of triacylgclyerol, which is stored in LDs. DGAT-2 is localized to LDs when animals are actively feeding. However, DGAT-2 is undetectable in starved animals. In contrast, another LD associated protein, the short-chain dehydrogenase 3 (DHS-3), remains stable under the same condition. Our obervations indicate that there may be differential mechanisms for the turnover of LD associated proteins.

In this study, I found that the degradation of DGAT-2 under starvation condition is regulated by the LD assoicated ancient ubiquitous protein 1 (AUP-1) in C. elegans. In addition, I found that AUP-1 may regulate the turnover of DGAT-2 through its interaction with components of the ERAD pathway. I propose that AUP-1 may recruit sepcific E2 and E3 enzymes to the LDs surface to ubiquitinate DGAT-2 in starved worms.