Apolipoprotein D in Lipid Metabolism and Its Functional Implication in Atherosclerosis and Aging

Perdomo, German; Dong, H. Henry

ApoD is a 29-kDa glycoprotein of 169 amino acids. ApoD is evolutionally conserved among species and is expressed in a variety of mammalian tissues. Although classifed as apolipoprotein, apoD belongs to the lipocalin family due to its structural adoptation of a βbarrel structure that is characteristic of lipocalins [40, 41] . ApoD is shown to be a multi-ligand binding protein that is capable of transporting small hydrophobic molecules such as arachidonic acid, steroid hormones, and cholesterol for metabolism or signaling [34] . Altered apoD expression has been associated with a number of pathological conditions, including breast carcinoma, prostate cancer, Parkinson's disease, Alzheimer, schizophrenia, bipolar disorder, etc [13-17, 34, 72, 74, 76-80] . Elevated apoD deposition is also detected in amyloid plaques in the brains of patients with Alzheimer with undefined pathophysiology [15, 79] . These data underscore the importance of apoD in the pathophysiology of cancer and neurological disorders. However, a comprehensive survey of apoD function is beyond the scope of this article. Instead, we center our review on apoD in lipid metabolism in relation to the pathogenesis of dyslipidemia and atherosclerosis, the two intertwined pathological traits that consequently predispose an at-risk individual to CAD.