Journal
ATHEROSCLEROSIS
Volume 243, Issue 2, Pages 499-509Publisher
ELSEVIER IRELAND LTD
DOI: 10.1016/j.atherosclerosis.2015.09.033
Keywords
miRNAs; miR-27b; LDLR; ABCA1; Lipid homeostasis; Atherosclerosis
Funding
- National Institutes of Health [R01HL107953, R01HL107953-04S1, R01HL106063, R01HL105945, 1F31AG043318, R01HL107794]
- American Heart Association [15SDG23000025, GRNT20460189]
- Howard Hughes Medical Institute International Student Research Fellowship
- Foundation Leducq Transatlantic Network of Excellence in Cardiovascular Research
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Rationale: Recently, there has been significant interest in the therapeutic administration of miRNA mimics and inhibitors to treat cardiovascular disease. In particular, miR-27b has emerged as a regulatory hub in cholesterol and lipid metabolism and potential therapeutic target for treating atherosclerosis. Despite this, the impact of miR-27b on lipid levels in vivo remains to be determined. As such, here we set out to further characterize the role of miR-27b in regulating cholesterol metabolism in vitro and to determine the effect of miR-27b overexpression and inhibition on circulating and hepatic lipids in mice. Methods and results: Our results identify miR-27b as an important regulator of LDLR activity in human and mouse hepatic cells through direct targeting of LDLR and LDLRAP1. In addition, we report that modulation of miR-27b expression affects ABCA1 protein levels and cellular cholesterol efflux to ApoA1 in human hepatic Huh7 cells. Overexpression of pre-miR-27b in the livers of wild-type mice using AAV8 vectors increased pre-miR-27b levels 50efold and reduced hepatic ABCA1 and LDLR expression by 50% and 20%, respectively, without changing circulating and hepatic cholesterol and triglycerides. To determine the effect of endogenous miR-27b on circulating lipids, wild-type mice were fed a Western diet for one month and injected with 5 mg/kg of LNA control or LNA anti-miR-27b oligonucleotides. Following two weeks of treatment, the expression of ABCA1 and LDLR were increased by 10-20% in the liver, demonstrating effective inhibition of miR-27b function. Intriguingly, no differences in circulating and hepatic lipids were observed between treatment groups. Conclusions: The results presented here provide evidence that short-term modulation of miR-27b expression in wild-type mice regulates hepatic LDLR and ABCA1 expression but does not influence plasma and hepatic lipid levels. (C) 2015 Elsevier Ireland Ltd. All rights reserved.
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