In addition to their role in fat storage, TAGs are also components of the lipid membrane. To analyze the involvement of membrane environment in the development of AFT, we manipulated the plasma membrane by depleting the worms of cholesterol, a component of membrane lipid rafts [23]. C. elegans are cholesterol auxotrophs; all of their cholesterol is captured through their diet, and acute effects of cholesterol depletion include a suppression of clathrin-independent endocytosis in neurons, a lipid raft-mediated process [24], suggesting that cholesterol is involved in the development or maintenance of particular membrane structures. If AFT requires specific membrane microdomain structures that include cholesterol, then altering the amount of cholesterol available to the animals may modify their ability to develop tolerance. We found that N2 and npr-1(ky13) animals reared on cholesterol-depleted media demonstrated a substantial suppression of the development of AFT (Figure 3a and 3b). In contrast, adding additional cholesterol to the medium did not affect the ability of animals to develop AFT (not shown). Together, these data suggest that the structure of the lipid bilayer is essential for the development of tolerance.
