Role of phosphatidylcholine biosynthesis in the regulation of lipoprotein homeostasis.
OBJECTIVE
This review summarizes the role of phosphatidylcholine metabolism in plasma lipoprotein homeostasis.


RESULTS
While it was previously known that phosphatidylcholine biosynthesis was required for normal hepatic VLDL secretion, recent studies have shown that both phosphatidylcholine biosynthetic pathways (the cytidine 5'-diphosphocholine and the phosphatidylethanolamine methylation pathways) are required. In addition, a requirement of acyl-coenzyme A synthetase 3, but not acyl-coenzyme A synthetase 1 or 4, for phosphatidylcholine synthesis and VLDL secretion is now documented. ABCA1 has been implicated in the transfer of phosphatidylcholine to apolipoproteinA-1 both during and after secretion of apolipoproteinA-1. Other studies have introduced the concept of reverse phosphatidylcholine transport in which both HDL and LDL supply phosphatidylcholine to the liver. An unexpected finding is that half of the phosphatidylcholine delivered to liver from lipoproteins is converted into triacylglycerol.


CONCLUSIONS
The liver is both a donor of phosphatidylcholine during the assembly and secretion of lipoproteins as well as a recipient of phosphatidylcholine from plasma lipoproteins.
Vance
Dennis E
DE
Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada. dennis.vance@ualberta.ca
D019916:Choline-Phosphate Cytidylyltransferase / Q000378:metabolism; D006706:Homeostasis; D008075:Lipoproteins, HDL / Q000378:metabolism; D008079:Lipoproteins, VLDL / Q000097:blood*; D010713:Phosphatidylcholines / Q000096:biosynthesis* / Q000378:metabolism; D050918:Phosphatidylethanolamine N-Methyltransferase / Q000378:metabolism; D049294:Phospholipid Transfer Proteins / Q000502:physiology
D008075:Lipoproteins, HDL; D008079:Lipoproteins, VLDL; D010713:Phosphatidylcholines; D049294:Phospholipid Transfer Proteins; D050918:Phosphatidylethanolamine N-Methyltransferase; D019916:Choline-Phosphate Cytidylyltransferase