Background:
Homocysteine (Hcy) has been suggested as an independent
risk factor for atherosclerosis. Apolipoprotein M (apoM) is a constituent of the HDL
particles. The goal of this study was to examine the serum levels of homocysteine and
apoM and to determine whether homocysteine influences apoM synthesis.
Methods:
Serum levels of apoM and Hcy in 17 hyperhomocysteinemia (HHcy) patients
and 19 controls were measured and their correlations were analyzed. Different
concentrations of homocysteine (Hcy) and LY294002, a specific phosphoinositide 3-
kinase (PI3K) inhibitor, were used to treat HepG2 cells. The mRNA levels were
determined by RT-PCR and the apoM protein mass was measured by western blot.
Results:
We found that decreased serum apoM levels corresponded with serum HDL
levels in HHcy patients, while the serum apoM levels showed a statistically significant
negative correlation with the serum Hcy levels. Moreover, apoM mRNA and protein
levels were significantly decreased after the administration of Hcy in HepG2 cells, and
this effect could be abolished by addition of LY294002.
Conclusions:
resent study demonstrates that Hcy downregulates the expression of
apoM by mechanisms involving the PI3K signal pathway.
Apolipoprotein M promotes cholesterol uptake and efflux from mouse macrophages