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Xu YX, Redon V, Yu H, Querbes W, Pirruccello J, Liebow A, Deik A, Trindade K, Wang X, Musunuru K, Clish CB, Cowan C, Fizgerald K, Rader D, Kathiresan S. Role of angiopoietin-like 3 (ANGPTL3) in regulating plasma level of low-density lipoprotein cholesterol. Atherosclerosis 2017; 268:196-206. [PMID: 29183623 DOI: 10.1016/j.atherosclerosis.2017.08.031] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 08/02/2017] [Accepted: 08/30/2017] [Indexed: 10/18/2022]
Abstract
BACKGROUND AND AIMS Angiopoietin-like 3 (ANGPTL3) has emerged as a key regulator of lipoprotein metabolism in humans. Homozygous loss of ANGPTL3 function causes familial combined hypolipidemia characterized by low plasma levels of triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C). While known effects of ANGPTL3 in inhibiting lipoprotein lipase and endothelial lipase contribute to the low TG and HDL-C, respectively, the basis of low LDL-C remains unclear. Our aim was to explore the role of ANGPTL3 in modulating plasma LDL-C. METHODS We performed RNAi-mediated gene silencing of ANGPTL3 in five mouse models and in human hepatoma cells. We validated results by deleting ANGPTL3 gene using the CRISPR/Cas9 genome editing system. RESULTS RNAi-mediated Angptl3 silencing in mouse livers resulted in very low TG, HDL-C and LDL-C, a pattern similar to the human phenotype. The effect was observed in wild-type and obese mice, while in hCETP/apolipoprotein (Apo) B-100 double transgenic mice, the silencing decreased LDL-C and TG, but not HDL-C. In a humanized mouse model (Apobec1-/- carrying human ApoB-100 transgene) deficient in the LDL receptor (LDLR), Angptl3 silencing had minimum effect on LDL-C, suggesting the effect being linked to LDLR. This observation is supported by an additive effect on LDL-C between ANGPTL3 and PCSK9 siRNAs. ANGPTL3 gene deletion induced cellular long-chain TG and ApoB-100 accumulation with elevated LDLR and LDLR-related protein (LRP) 1 expression. Consistent with this, ANGPTL3 deficiency by gene deletion or silencing reduced nascent ApoB-100 secretion and increased LDL/VLDL uptake. CONCLUSIONS Reduced secretion and increased uptake of ApoB-containing lipoproteins may contribute to the low LDL-C observed in mice and humans with genetic ANGPTL3 deficiency.
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Affiliation(s)
- Yu-Xin Xu
- Center for Genomic Medicine and Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Valeska Redon
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, 11-125 Translational Research Center, 3400 Civic Center Blvd, Building 421, Philadelphia, PA 19104-5158, USA
| | - Haojie Yu
- Department of Stem Cell and Regenerative Biology, Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - William Querbes
- Alnylam Pharmaceuticals, 300 Third Street, 3rd Floor, Cambridge, MA 02142, USA
| | - James Pirruccello
- Center for Genomic Medicine and Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Abigail Liebow
- Alnylam Pharmaceuticals, 300 Third Street, 3rd Floor, Cambridge, MA 02142, USA
| | - Amy Deik
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - Kevin Trindade
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, 11-125 Translational Research Center, 3400 Civic Center Blvd, Building 421, Philadelphia, PA 19104-5158, USA
| | - Xiao Wang
- Cardiovascular Institute, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia 19104, USA
| | - Kiran Musunuru
- Cardiovascular Institute, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia 19104, USA
| | - Clary B Clish
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - Chad Cowan
- Department of Stem Cell and Regenerative Biology, Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA; Center for Regenerative Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Kevin Fizgerald
- Alnylam Pharmaceuticals, 300 Third Street, 3rd Floor, Cambridge, MA 02142, USA
| | - Daniel Rader
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, 11-125 Translational Research Center, 3400 Civic Center Blvd, Building 421, Philadelphia, PA 19104-5158, USA
| | - Sekar Kathiresan
- Center for Genomic Medicine and Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA 02114, USA.
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