Homocysteine and lipids: S-Adenosyl methionine as a key intermediate

Abstract 

An association between hyperlipidemia and hyperhomocysteinemia (HHCY) has been suggested. This link is clinically important in management of vascular risk factors especially in elderly people and patients with metabolic syndrome. Higher plasma homocysteine (Hcy) was associated with lower high-density lipoprotein (HDL)-cholesterol level. Moreover, HHCY was associated with disturbed plasma lipids or fatty liver. It seems that hypomethylation associated with HHCY is responsible for lipid accumulation in tissues. Decreased methyl group will decrease the synthesis of phosphatidylcholine, a major phospholipid required for very low-density lipoprotein (VLDL) assembly and homeostasis. The effect of Hcy on HDL-cholesterol is probably related to inhibiting enzymes or molecules participating in HDL-particle assembly.

Abbreviations: Hcy, homocysteine, HHCY, hyperhomocysteinemia, SAM, S-adenosyl methionine, SAH, S-adenosylhomocysteine, PC, phosphatidylcholine, PE, phosphatidylethanolamine, PEMT, phosphatidyl ethanolamine methyltransferase, LCAT, lecithin-cholesterol acyltransferase, MTHFR, methylene tetrahydrofolate reductase, HDL, high-density lipoprotein, LDL, low-density lipoprotein, VLDL, very low-density lipoprotein, BHMT, betaine homocysteine methyltransferase, SREBP-1, sterol regulatory element-binding protein, UPR, unfolded protein response, CYP7A1, cholesterol 7α-hydroxylase

Keywords: Homocysteine, Cholesterol, Choline, Phosphatidylcholine, Betaine, Methionine