High levels of homocysteine downregulate apolipoprotein E expression via nuclear factor kappa B

Figure 1 High homocysteine doses downregulate apoE expression in HEK-293 cells. ApoE expression in HEK-293 cells exposed for 24 h to increasing concentrations of homocysteine (50-750 μmol/L) was assessed by RT-PCR and immunoblotting. A: High homocysteine concentrations (250-750 μmol/L) significantly decreased apoE mRNA levels in HEK-293 cells; in contrast, lower doses of homocysteine (100 μmol/L), did not affect the expression level as compared to the control cells. The expression of β-actin was used for normalization; B: Treatment of HEK-293 cells with 500 μmol/L homocysteine, but not with 50 μmol/L homocysteine, dramatically reduced apoE protein expression. RT-PCR: Reverse transcriptase polymerase chain reaction; ApoE: Apolipoprotein E.