Fig. 1.

Simplified representation of the major metabolic pathways responsible for the uptake, transport, synthesis, and utilisation of lipids in the liver.

FA and cholesterol are the building blocks of most complex lipids. They can either be synthesised (orange arrows) via DNL (up to 25% of FA pool) and cholesterol synthesis (up to 80% of cholesterol pool) or they can be taken directly from the circulation. FA are subjected to FAO (red arrow) via a series of catabolic reactions, which are carried out in the mitochondria to generate ATP or used to form complex lipids. Lipids play structural (blue), signalling (green) or energy storage (yellow) functions. BA, bile acids; Cer, ceramides; Chol, cholesterol; ChoE, cholesterol esters; DG, diglyceride; DNL, de novo lipogenesis; FAO, fatty acid oxidation; FFA, free fatty acids; LPC, lysophosphatidylcholine; LPE, lysophosphatidylethanolamine; LPI, lysophosphoinositide; LPS, lysophosphatidylserine; MUFA, monounsaturated FA; PA, phosphatidate; PC, phosphatidylcholine; PE, phosphatidylethanolamine; PI, phosphoinositide; PS, phosphatidylserine; PUFA, polyunsaturated FA; S1P, sphingosine-1-phosphate; SM, sphingomyelin; TG, triglyceride.