BackgroundGenistein has been proved in vitro and in vivo to lower LDLR level. It is also widely consumed and implicated for its anti-atherogenic effects. However, the molecular mechanism by which genistein lowers the LDL level is still unknown.ObjectiveTo understand the anti-atherogenic molecular mechanism of action, genistein was investigated for its impact on the expression of LDLR, the receptor for LDL cholesterol, and related signaling pathways in a human hepatoma cell line.DesignHepG2 cell was used for the experiments. Genistein with different concentrations was diluted in media and was incubated for 24 h or more as indicated. Protein levels were measured by western blotting, and mRNA expression was detected by RT-qPCR. Chromatin immunoprecipitation assay (CHIP) assay was used to determine protein binding levels, and luciferase assay was used to measure promoter activity.ResultGenistein increased the mRNA and protein levels of LDLR in a time-dependent manner. Genistein increased the transcriptional activity of the LDLR promoter containing the reporter gene (pLDLR-luc, −805 to +50). But the sterol regulatory element deletion mutant construct failed to be activated by genistein. Genistein increased the nuclear fraction of SREBP-2 and the DNA-binding activity of SREBP-2 to LDLR promoter, as assessed by CHIP. The genistein-phosphorylated JNK inhibitor (SP600126) abolished the genistein-stimulated levels of LDLR and the nuclear SREBP-2. The addition of cholesterol up to 5 µg/mL for 24 h did not affect the effect of genistein on LDLR protein expression. Even the addition of 40 µM genistein increased the cholesterol uptake by more than 10% in the human hepatoma cell line.ConclusionOur data support the idea that genistein may have anti-atherogenic effects by activating JNK signals and SREBP-2 processing, which is followed by the upregulation of LDLR.

The anti-hypercholesterolemic effect of 11 Lactobacillus isolates was investigated in vitro by measuring remaining cholesterol in growth media, growth ability in media supplemented with cholesterol, and BSH activity. Among the selected isolates, DLBSH104, DLBSH122, and DLBSK207 have demonstrated outstanding potential as cholesterol-lowering cultures. The three isolates showed high cholesterol removal by growing cells, whereas resting and dead cells showed less cholesterol removal. Furthermore, visualization of those isolates in growing and non-growing states by SEM showed the ability of DLBSH104 to attach cholesterol to their cell surface. In contrast, alteration of DLBSH122 and DLBSK207 cells did not involve surface attachment of cholesterol. Thus, the isolates’ ability to remove cholesterol is mainly attributed to the cells’ metabolically active state that assimilates and incorporates cholesterol into the cell membrane as reflected by a significantly higher cholesterol removal in a growing state than a non-growing state. Only in DLBSH104 did cholesterol removal also involve attachment on the cell surface. Moreover, DLBSH104 has beneficially affected the host cell by a significant reduction of NPC1L1 mRNA levels that are responsible for intestinal cholesterol absorption. In hepatic cells, cell-free supernatant (CFS) from DLBSH104 and DLBSK207 were able to reduce LDLR and HMGCR mRNA at the transcription level. To sum up, L. helveticus DLBSH104 and L. plantarum DLBSK207 are confirmed as isolates with an anti-hypercholesterolemic effect.

Genistein has been implicated for its anti‐atherogenic effects. To understand the anti‐atherogenic mechanism of action genistein was investigated its impact on hepatic cholesterol uptake, the expression of LDLR which is the receptor for LDL‐cholesterol, and related signaling pathways in human hepatoma HepG2 cells. the The addition of 40 μM genistein increased cholesterol uptake into HepG2cells. Genistein increased mRNA and protein levels of LDLR in a time‐dependent manner. The addition of cholesterol up to 5 μg/mL for 24 hours did not significantly affect the effect of genistein towards LDLR protein expression. Genistein increased the transcriptional activity of LDLR promoter containing reporter gene (pLDLR‐luc, −805 to +50). But sterol‐regulatory element (SRE) deletion mutant construct was failed to be activated by genistein. Genistein increased the nuclear fraction of SREBP‐2 and DNA binding activity of SREBP‐2 to LDLR promoter as assessed by chromatin immunoprecipitation assay (CHIP). Genistein phosphorylated JNKs. JNK inhibitor (SP600126) abolished genistein‐stimulated levels of LDLR and nuclear SREBP‐2. To minimize the effects of c‐Jun, a transcription factor activated by JNK signals, a truncated LDLR luciferase construct that was contained SRE but lacked the c‐jun putative binding site was constructed. Genistein was still able to boost the transcriptional activity of the truncated LDLR construct. In conclusion, our data supports that genistein may have the anti‐atherogenic effects by increasing hepatic LDL cholesterol uptake via activating JNK signals and SREBP‐2 processing, which is followed by up‐regulation of LDLR.