Control of Very-Low Density Lipoprotein Secretion by N-Ethylmaleimide-Sensitive Factor and miR-33
Rationale: Several reports suggest that antisense oligonucleotides against miR-33 might reduce cardiovascular risk in patients by accelerating the reverse cholesterol transport pathway. However, conflicting reports exist regarding the impact of anti-miR-33 therapy on the levels of very low-density lipoprotein-triglycerides (VLDL-TAG).
Objective: We test the hypothesis that miR-33 controls hepatic VLDL-TAG secretion.
Methods and Results: Using therapeutic silencing of miR-33 and adenoviral overexpression of miR-33, we show that miR-33 limits hepatic secretion of VLDL-TAG by targeting N-ethylmaleimide-sensitive factor (NSF), both in vivo and in primary hepatocytes. We identify conserved sequences in the 3'UTR of NSF as miR-33 responsive elements, and show that Nsf is specifically recruited to the RNA-Induced Silencing Complex (RISC) following induction of miR-33. In pulse-chase experiments, either miR-33 overexpression or knock-down of Nsf lead to decreased secretion of apoproteins and TAG in primary hepatocytes, compared to control cells. Importantly, Nsf rescues miR-33-dependent reduced secretion. Finally, we show that overexpression of Nsf in vivo increases global hepatic secretion and raises plasma VLDL-TAG.
Conclusions: Together, our data reveal key roles for the miR-33-NSF axis during hepatic secretion, and suggest that caution should be taken with anti-miR-33-based therapies since they might raise pro-atherogenic VLDL-TAG levels.
- Received November 25, 2013.
- Revision received April 17, 2014.
- Accepted April 21, 2014.