Journal
BIOLOGICAL & PHARMACEUTICAL BULLETIN
Volume 31, Issue 6, Pages 1182-1191Publisher
PHARMACEUTICAL SOC JAPAN
DOI: 10.1248/bpb.31.1182
Keywords
cytochrome P450 lanosterol 14-alpha demethylase; RNA interference; cholesterol; low-density lipoprotein; low-density lipoprotein receptor
Categories
Funding
- Chinese Natural Science Foundation [30470868, 30571358, 30671508]
- Beijing Natural Science Foundation [5052017]
- Chinese 973 Project [2006CB504003, 2007CB947401]
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Cytochrome P450 lanosterol 14-alpha demethylase (CYP51), participated in keeping serum cholesterol homeostasis, is a key enzyme to synthesize cholesterol from lanosterol. Here we focused on investigating the mechanism of CYP51 in modulating serum cholesterol levels in mouse through RNA interference (RNAi). Mice fed on normal or high fat high cholesterol (HFHC) diets were individually treated with small interference RNA (siRNA) of CYP51 gene by tail vein injection. The results showed that administrated single dose of 10 mu g CYP51-siRNAs for 48 h resulted in significantly depletion of CYP51 mRNA in liver of mice fed on normal diet (from 40 to 60%, p<0.05). CYP51-siRNAs exerted the inhibition in a dose dependent manner (from 26% in 5 mu g to 40% in 20 mu g, p<0.05) and most inhibitive effect from day 3 to day 6 (over 50%, p<0.05) after the treatment. Six days after administration of 30 mu g CYP51-siRNAs (20 mu g on day 0 and 10 mu g on day 3), CYP51 mRNA (normal: 50%); HFHC: 70%, p<0.05) and protein levels (normal and HFHC: over 400%, p<0.05) were significantly knocked down in mice liver. Interestingly, low-density lipoprotein receptor (LDLR) expression was significantly elevated compared with controls in hepatic cells after CYP51-siRNAs (mRNA: about 2 times; protein: about 1.6 times, p<0.05). As a consequence, about 50% of sera low-density lipoprotein cholesterol (LDL-ch) were significantly reduced (p<0.05). The effect on LDLR increase and LDL-ch reduction lasted 8d after a single 20 mu g CYP51-siRNAs injection. In addition, CYP51-siRNAs could not cause any fatty liver compared with Buffer-group and did not interfere with mice ovulation. In conclusion, these data demonstrated that CYP51-siRNAs silenced CYP51 in mouse liver and down-regulated plasma LDL-ch levels. The potential mechanism of LDL-ch reduction may be related to up-regulated LDLR expression of hepatic cells. It indicated that there was a cholesterol levels link-modulation system between cholesterol synthetic pathway through CYP51 and cholesterol transport pathway through LDLR in vivo.
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