Fellowship for Liu: The Role of D2 in the Metabolism of Atypical Fatty Acids in Adipose Tissue

The ATP binding cassette (ABC) transporter, ABC02 (02), is one of four ABC transporters that contains a peroxisomal targeting signal in its primary structure. 02 is expressed in a number of tissues, but is most highly expressed in fat. Mice deficient in 02 have increased oxidative stress in brain and adrenal and accumulate end products of lipid peroxidation (malondialdehyde) in adipose tissue. Lipid peroxides are pro-inflammatory and proatherogenic, suggesting that their clearance in adipose tissue may playa protective role in the development of cardiovascular diseases. Reductions in adipose lipid peroxide clearance capacity may contribute to the development of dysfunctional adipose tissue and metabolic syndromes. The central hypothesis of this proposal is that 02 is a peroxisomal protein that facilitates the clearance of atypical fatty acids to maintain normal adipocyte function. The aims of this proposal are 1) to determine the subcellular localization of 02 in adipocytes 2) to determine the effect of 02 on the clearance of dietary atypical fatty acids (very long chain fatty acids, VLCF A) and endogenous oxidized lipids (oxidized LOL) 3) to determine if 02 opposes lipid-induced oxidative stress, adipokine expression and insulin resistance in adipocytes. The subcellualr localization of 02 will be determined using two complementary approaches. First, immunofluorescence of 02 in adipose tissue will be colocalized with organelle specific markers using confocal imaging. Second, the 02 containing compartments will be immunoisolated using 02 antibody coupled magnetic beads, and examined for the presence of organelle specific markers by immunoblotting. Next, the effect of 02 on the metabolism of VLCFA and oxidized LOL (oxLOL) will be determined in 3T3-L 1 adipocytes expressing scrambled and specific shRNAs directed against 02. Finally, the ability of 02 to oppose lipid induced oxidative stress, adipokine dysregulation and insulin resistance in adipocytes will be tested using the same cell lines described in aim 2.