Figure 1.

Regulation of polyunsaturated fatty acids (PUFA) synthesis and phospholipid metabolism by liver X receptors (LXRs). PUFA requires the initial activation of the substrate fatty acid into an acyl-CoA by an acyl-CoA synthase (ACSL3 and ACSL4) and the successive actions of delta 5 desaturase (FADS1), elongase (ELOVL5), and delta 6 desaturase (FADS2). LXR regulates directly or indirectly through sterol responsive element binding protein (SREBP) all these classes of enzymes. Interestingly, LXR activation also increases lysophosphatidylcholine acyltransferase (LPCAT3), which promotes the preferential incorporation of eicosapentaenoic acid (EPA) and arachidonic acid (AA) into glycerophospholipids which can be further exchanged by phospholipid transfer protein (PLTP).